You are here: Resist Wiki
The Resist Wiki is a knowledge platform covering current technologies of micro electronics which is permanently updated to add further information from our research and development activities.
We have broken it down into the six topics “basics, e-beam resist, photoresist, protective resist, bottom resist and process chemicals” so that you can quickly find what you are looking for.
Have fun while reading!
Please contact our customer service.
All 19 /Adhesions Promoter 0 /Allresist 0 /AR NEWS 0 /Basic Chemistry 7 /Basics 0 /Bottom Resist 0 /Developer 0 /E-Beam Resist 0 /FAQ 0 /FAQ 0 /General 0 /General 0 /General 0 /General 0 /Home 0 /Home Resist 0 /Negative 0 /Negative 0 /News 0 /Newspaper Article 0 /Other Resists 0 /Other Resists 0 /Photoresist 0 /Positive 0 /Positive 0 /Press 0 /Process Chemicals 0 /Process Information 4 /Process Procedures 8 /Protective Resist 0 /R&D 0 /R&D Projects 0 /Remover 0 /Resist of the month 0 /Resist Wiki 0 /Scientific Article 0 /Stopper 0 /Thinner 0 /z-SX-AR-PC 5000/41 0 /z_AR 300-12 0 /z_AR 300-26 / 300-35 0 /z_AR 300-40 0 /z_AR 600-01 - 09 0 /z_AR-N 4400 0 /z_AR-N 4600 0 /z_AR-P 3100 0 /z_AR-P 617 0 /z_AR-P 6200 0 /z_AR-P 630-670 0 /z_AR-P-8100 0 /z_AR-PC 5090/91 0 /z_SX AR-N 8200 0 /z_SX AR-P 3500/8 0
Aluminium structures developed directly
The fabrication of aluminium structures generally involves the production of a resist mask with subsequent wet-chemical etching. The more elegant procedure of direct development can be applied if the negative resist SX AR-
27. February 2013/by AllAdminChemical dry etching
Chemical dry etchings fall into two categories depending on the etching principle. 1. A more chemical etching refers to a process in which the substrate is attacked by radicals and converted into volatile compounds.
31. August 2012/by AllAdminComposition of photoresists
Photoresists are particularly employed in microelectronics and in microsystems technology to generate µm- and sub-µm structures.
13. July 2012/by AllAdminCross linker
The patterning of negative resists is based on the stabilization of exposed areas in the presence of cross-linking agents. Radical starters like e.g. azo-bis(isobutyronitrile) (AIBN)
13. July 2012/by AllAdminDetermining the conductivity of Electra 92 layers on glass
The specific conductivity of thin films can be determined with various methods, e.g. by non-contact eddy current mapping or also after a direct contact using the four-point probe method (four-peak measurement).
19. January 2016/by AllAdminExposure
Contact exposure refers to a process in which a photo mask and a substrate are brought into direct contact. This procedure leads to the best resolution of all shadow projections.
27. February 2013/by AllAdminForays through the lithography of microelectronics (Matthias Schirmer)
Due to the fast-paced development of photolithography since the 1990s, only a short summary of the different techniques and applications can be given here. For in-depth information on the multitude of facts, technologies and procedures presented in each chapter, the added references should be consulted.
20. May 2020/by AllAdminInterference lithography
Interference lithography is a less frequently used method for patterning. The basic principle is the same as in interferometry or also in holography.
4. July 2016/by AllAdminOther resist components
Solvents are the main component of all resists, with solvent contents ranging from 50% (thick resists) to up to 99% (spray resists).
16. July 2012/by AllAdminPhotosensitive components
The p hoto sensitive components of our positive photoresists belong to the group of naphtho qu inone d iazides (NQD).
13. July 2012/by AllAdminPolymers (film formers)
Polymethyl methacrylates (PMMAs) are widely used e.g. in electron beam lithography. PMMAs are produced by polymerisation of methacrylic acid esters in the presence of radical starters
20. March 2013/by AllAdminPrinciple and functioning
Positive resist The addition of photoactive compounds (PACs, naphthoquinone diazide (NQD)) to alkali-soluble novolacs reduces the alkali-solubility of resists films.
24. July 2012/by AllAdminProcess conditions
Air bubbles often occur when resist bottles are e.g. shaken or moved around before coating, or if a resist is diluted. They may also appear if the coating step is performed immediately after opening of the resist bottle, particularly if the resist temperature is not allowed to adjust to room conditions.
11. May 2022/by Process procedure e-beam resist
Process procedure e-beam resist
Development of PMMA films PMMA films can only be developed with solvent-based developers. Aqueous-alkaline PMMA developers will not attack PMMA - PMMA is even used as protective coating in the presence of strongly alkaline solutions.
30. July 2012/by AllAdminDevelopment of PMMA films PMMA films can only be developed with solvent-based developers. Aqueous-alkaline PMMA developers will not attack PMMA - PMMA is even used as protective coating in the presence of strongly alkaline solutions.
Process procedure photoresists
When new and clean substrates (wafers) are used, a heating at approximately 200 °C for several minutes (2-3 min, hot plate) is sufficient for drying. Substrates should however subsequently be processed quickly.
30. July 2012/by AllAdminStabilisation/ hardening of resist films
A large variety of applications require structured resist architectures which achieve long-term stability against organic solvents after a subsequent hardening step.
20. May 2015/by AllAdminStorage and ageing
Photoresists are light-sensitive, their properties change in the presence of light or elevated temperatures. Resists age during storage and are therefore supplied in light-protected amber glass bottles,
13. July 2012/by AllAdminUV-curing
Photoresist structures of standard resists possess a softening point of 115 - 130 °C. During subsequent thermal processes (plasma etching, sputtering or others), these temperatures are easily exceeded.
30. July 2012/by AllAdminWet chemical etching
In wet-chemical etchings, the chemical bonds of the material to be processed are cleaved by mostly aggressive etch media and converted into soluble substances.
Wet-chemical etching procedures thus place very high demands on the protective resist layer. Decisive process parameters are, in addition to the choice of a suitable resist, the etching medium itself, the duration of the etching step and the etching temperature (which determines the reaction speed). Another important aspect concerns the adhesion properties of the resist on the substrate to be etched. An insufficient adhesion of the resist to the substrate may result in the detachment of the resist layer which renders the substrates unusable for any further applications. Adhesion problems and cracks in the resist layer frequently often appear at first at resist edges, since local heat and gas development lead to an additional mechanical load in these areas. Especially in the case of HF-containing etchings, additional large-area detachments of the resist are possible due to the diffusion of fluoride ions through the resist layer; the substrate surface is consequently attacked. Resist adhesion can generally be improved by a suitable pre-treatment of the substrate (adhesion promoter) and an optimised process management (sufficiently high resist thickness, adapted soft-bake and PEB, possible final final-hard bake).
Distinguished are anisotropic etching (rate-limited etching in which the activation energies are different for each crystal plane as in the case of Si etching with concentrated, hot KOH) and isotropic etching which occurs with amorphous materials (glasses, metals). In the case of isotropic etching, an under-etching of the resist layer cannot be avoided even if resist adhesion is optimal. If mass transport (diffusion of active components and etched products) does not limit the etch rate, a lateral under-etching occurs in proximity to the substrate surface which is comparable to the etching depth.
Specific etching mixtures are used for each material/substrate, and resists have to be selected with regard to their compatibility with the etching solution. After wet-chemical etching, intensive and multi-stage rinsing with DI water is required. These rinsing steps completely remove any etching solution which penetrated into the resist layer and prevents possible later resist damages. Insufficient rinsing may lead to a concentration of the etching solution during the final drying step, which then results in crack formation and altered/poor removing properties.
Novolac-based resists generally show a good stability against non-oxidizing acids and corrosive iodine solutions (KI*I2). Concentrated hydrochloric acid is thus generally no problem, while concentrated nitric acid or concentrated sulphuric acid solutions strongly attack the resist layers.
Diluted hydrofluoric acid (concentration < 6 %) is well tolerated, but more concentrated HF solutions causes problem with respect to the adhesion properties of the resist which are due to a diffusion of F– ions. The concentration of „free“ F– ions can however be reduced if NH4F-buffered HF etch is used (BOE process). At the same time, the formation of highly reactive HF2– ions induces a considerable increase of the etch rate and a more controllable, more homogeneous etching process. Novolac-based resists show a significantly higher stability against buffered HF solutions.
Novolac-based resists are quickly attacked in strongly alkaline etching solutions. PMMA (resist AR-PC 503) is well suited for a use as backside protection, e.g. for etchings with hot, concentrated KOH. The substrates (also the edges!) must however be coated without any defects in order to avoid a rapid detachment of the protective layer due to under-etching.
31. August 2012/by AllAdminWet-chemical etching procedures thus place very high demands on the protective resist layer. Decisive process parameters are, in addition to the choice of a suitable resist, the etching medium itself, the duration of the etching step and the etching temperature (which determines the reaction speed). Another important aspect concerns the adhesion properties of the resist on the substrate to be etched. An insufficient adhesion of the resist to the substrate may result in the detachment of the resist layer which renders the substrates unusable for any further applications. Adhesion problems and cracks in the resist layer frequently often appear at first at resist edges, since local heat and gas development lead to an additional mechanical load in these areas. Especially in the case of HF-containing etchings, additional large-area detachments of the resist are possible due to the diffusion of fluoride ions through the resist layer; the substrate surface is consequently attacked. Resist adhesion can generally be improved by a suitable pre-treatment of the substrate (adhesion promoter) and an optimised process management (sufficiently high resist thickness, adapted soft-bake and PEB, possible final final-hard bake).
Distinguished are anisotropic etching (rate-limited etching in which the activation energies are different for each crystal plane as in the case of Si etching with concentrated, hot KOH) and isotropic etching which occurs with amorphous materials (glasses, metals). In the case of isotropic etching, an under-etching of the resist layer cannot be avoided even if resist adhesion is optimal. If mass transport (diffusion of active components and etched products) does not limit the etch rate, a lateral under-etching occurs in proximity to the substrate surface which is comparable to the etching depth.
Specific etching mixtures are used for each material/substrate, and resists have to be selected with regard to their compatibility with the etching solution. After wet-chemical etching, intensive and multi-stage rinsing with DI water is required. These rinsing steps completely remove any etching solution which penetrated into the resist layer and prevents possible later resist damages. Insufficient rinsing may lead to a concentration of the etching solution during the final drying step, which then results in crack formation and altered/poor removing properties.
Novolac-based resists generally show a good stability against non-oxidizing acids and corrosive iodine solutions (KI*I2). Concentrated hydrochloric acid is thus generally no problem, while concentrated nitric acid or concentrated sulphuric acid solutions strongly attack the resist layers.
Diluted hydrofluoric acid (concentration < 6 %) is well tolerated, but more concentrated HF solutions causes problem with respect to the adhesion properties of the resist which are due to a diffusion of F– ions. The concentration of „free“ F– ions can however be reduced if NH4F-buffered HF etch is used (BOE process). At the same time, the formation of highly reactive HF2– ions induces a considerable increase of the etch rate and a more controllable, more homogeneous etching process. Novolac-based resists show a significantly higher stability against buffered HF solutions.
Novolac-based resists are quickly attacked in strongly alkaline etching solutions. PMMA (resist AR-PC 503) is well suited for a use as backside protection, e.g. for etchings with hot, concentrated KOH. The substrates (also the edges!) must however be coated without any defects in order to avoid a rapid detachment of the protective layer due to under-etching.
All 76 /Adhesions Promoter 0 /Allresist 0 /AR NEWS 0 /Basic Chemistry 0 /Basics 0 /Bottom Resist 0 /Developer 0 /E-Beam Resist 0 /FAQ 0 /FAQ 20 /General 0 /General 0 /General 5 /General 0 /Home 0 /Home Resist 0 /Negative 0 /Negative 18 /News 0 /Newspaper Article 0 /Other Resists 24 /Other Resists 0 /Photoresist 0 /Positive 13 /Positive 0 /Press 0 /Process Chemicals 0 /Process Information 0 /Process Procedures 0 /Protective Resist 0 /R&D 0 /R&D Projects 0 /Remover 0 /Resist of the month 0 /Resist Wiki 0 /Scientific Article 0 /Stopper 0 /Thinner 0 /z-SX-AR-PC 5000/41 0 /z_AR 300-12 0 /z_AR 300-26 / 300-35 0 /z_AR 300-40 0 /z_AR 600-01 - 09 0 /z_AR-N 4400 0 /z_AR-N 4600 0 /z_AR-P 3100 0 /z_AR-P 617 0 /z_AR-P 6200 0 /z_AR-P 630-670 0 /z_AR-P-8100 0 /z_AR-PC 5090/91 0 /z_SX AR-N 8200 0 /z_SX AR-P 3500/8 0
1. What are photoresists composed of, and how do they work?
Photoresists (also photo coatings) are primarily used in micro electronics and micro system technologies for the production of µm- and sub-µm structures. These resists are generally deposited by spin coating in a range between 250
21. August 2008/by AllAdmin10. Which developers are optimal for photoresist, and how do factors like developer concentration and temperature influence the result?
During development, a positive tone resist film is structured by a removal of exposed areas, while unexposed areas are removed when negative resists are used. To achieve reproducible results,
12. August 2008/by AllAdmin11. How can resist coatings be removed again?
For the removal of softbaked coatings, polar solvents such as e.g. the respective resist thinner AR 300-12 (methoxy propyl acetate = PGMEA) and the remover AR 600-70 (acetone-based)
11. August 2008/by AllAdmin12. What is the application range of protective coatings?
Protective coatings are available for a large variety of applications, e.g. for the protection of wafer-backsides: or mechanical protection during transport
10. August 2008/by AllAdmin13. How do image reversal resists work?
With image reversal resists such as AR-U 4000, positive or negative tone images can be generated of the optical transmitted pattern depending on the manufacturing process. If the resist is processed according to the general protocol for positive resists without any additional steps,
9. August 2008/by AllAdmin14. How can undercut patterns (lift-off structures) be produced in one- or two layer systems?
A variety of one- or two layer systems are available which generate undercut patterns. For example, AR-P 5350 is a one layer system suitable for the production of metallic vapour phase structures.
8. August 2008/by AllAdmin15. How can thick films of > 10 µm be processed in an optimal way?
Coating: As a general rule for the coating with thick positive and negative tone resists, resists should be left undisturbed for several hours up to one day before processing ( » Question 6 Optimum coating parameters,
7. August 2008/by AllAdmin16. Which resolution and which contrast can be obtained with photoresists?
The resolution of resists is influenced by several parameter such as e.g. the type of mask liner used, most of the respective NA (numerical aperture), film thickness, exposure wavelength,
6. August 2008/by AllAdmin17. How high is the plasma etch resistance of photoresists?
Photoresists of the AR-product lines 3000 to 4000 display a very high etch resistance due to the polymers which are used for their production. This is especially the case for dry etch processes such as e.
5. August 2008/by AllAdmin18. How high is the etch resistance of photoresist in the presence of strong acids?
Concentrated oxidising acids (sulphuric acid, nitric acid, aqua regia 1) , piranha 2) ) attack resist films already at room temperatures and are often used as removers for persistent resist structures.
4. August 2008/by AllAdmin19. Which photoresists are suitable for hydrofluoric acid (HF) etching?
The positive tone photoresist X AR-P 3100/10 is extremely adhesion enhanced and thus suitable for HF etching of up to 5 % HF. In particular on glass or silicon oxide, a pre-treatment of substrates with the adhesion promoter AR 300-
3. August 2008/by AllAdmin2. For how long are photoresists stable, and what are the optimal storage conditions?
Photoresists are light-sensitive, they are affected by light exposure and high temperatures, and age-related changes occur during storage. Resists are therefore filled in light-protected amber glass bottles,
20. August 2008/by AllAdmin20. How high is the solvent resistance of photoresist films?
With respect to the source materials used, photoresists fall into two different categories: PMMA resists (protective coating AR-PC 5000/4, -503, 504, SX AR-N 4800) Novolak resists (AR-
2. August 2008/by AllAdmin3. How may age-related changes influence the quality of a photoresist?
During storage, red azo dyes develop due to a thermal chemical reaction of the light-sensitive component with the novolak, causing a darkening of the resist. Even small amounts of the dye lead to darkening,
19. August 2008/by AllAdmin4.What is the optimal pre-treatment of substrates for photoresists?
If new and clean substrates (wafers) are used, a bake at approximately 200 °C for several minutes is sufficient for drying, but the substrates have to be processed quickly afterwards.
18. August 2008/by AllAdmin5. What are the adhesion features of photoresists on different wafers?
Adhesion between coating and substrates is a very sensitive feature. Smallest changes of the cleaning procedures or the process parameters can have a fatal impact on the adhesive strength.
17. August 2008/by AllAdmin6. What are the optimum coating parameters for photoresists in order to achieve good film images?
Prior to the coating procedure, resists have to be adjusted to the temperature of the (preferably air-conditioned) working area. If the resist is too cold, air moisture may precipitate on the resist.
16. August 2008/by AllAdmin7. Why may air bubbles develop in photoresist films, and how can they be avoided?
Bubbles after spin deposition are in most cases air bubbles, e.g. if the resist bottle was agitated or moved around, or if the resist was diluted prior to the coating step. Coating procedures performed immediately after bottle opening,
15. August 2008/by AllAdmin8. What is the function of the softbake of photoresist films after the coating?
Just recently coated resist films still contain a substantial amount of residual solvent, depending on the respective film thickness. The subsequent bake step at 90 – 100 °C is performed in order to dry the resist films,
14. August 2008/by AllAdmin9. How are photo resists exposed, and how can the optimum exposure dose be determined? How long can coated and exposed substrates be stored prior to exposure?
The exposure is performed using masks in suitable exposure systems such as e.g. steppers (i-, g-line), mask aligners or contact exposure systems in the appropriate spectral working range.
13. August 2008/by AllAdminAdaptable two-layer resist AR-BR 5460 for variable lift-off structures
Bottom resist AR-BR 5460 has already been used for a decade in combination with positive (e.g. AR-P 3510) or negative resists (e.g. AR-N 4340) for a large variety of lift-off applications.
21. July 2015/by AllAdminAdhesive strength
Adhesive agents serve to improve adhesion, e.g. the adhesion promoter AR 300-80, which is applied by spin coating as thin layer of approximately 15 nm immediately before the resist coating. It is also possible to evaporate HMDS on the substrate, in this process, the monomolecular coat on the wafer surface improves adhesion, because it becomes hydrophobic and better attaches to the resist.
24. May 2022/by Alkali-stable and solvent-stable negative resist
Most novolac-based photoresists are characterized by high etch stability in the presence of acids (except in highly concentrated oxidizing acids or in concentrated hydrofluoric acid
16. July 2012/by AllAdminAlkali-stable positive resist obtained after treatment with HMDS
A large variety of applications include a wet-chemical etching step which very often involves highly alkaline etching baths.
19. January 2016/by AllAdminAlkali-stable, easily structurable positive resist SX AR-P 5900/8
Resist AR-P 5900/4 is already well established on the market for many years. Structures of this positive resist are characterized by a considerably higher alkaline stability as compared to standard positive resists (e.g. AR-P 3510 or AZ resists).
13. June 2014/by AllAdminAqueous negative resist based on gelatine
In the presence of catalytic iron salts, it is possible to photochemically induce a negative crosslinking of gelatine. Coated substrates are for this purpose exposed and briefly swivelled in diluted hydrogen peroxide solution which acts as crosslinking agent.
13. June 2014/by AllAdminAtlas 46 for nanoimprint lithography
The new development Atlas 46 could also be successfully used for nanoimprinting (University of Wuppertal, working group of Prof. Scheer). In a first step, nanostructures were produced with the negative-working resist
15. January 2018/by AllAdminATLAS 46 in general
The resists Atlas 46 S = AR-N 4600-10 and Atlas 46 R = AR-N 4650-10 are photoresists with negative effect and high layer thickness with extremely stable resist structures. In addition, AR-N 4650-10 is removable easily and thus very well suited for photolithographic and electro-plating applications. The characteristics of AR-N 4600-10 are comparable to those of SU-8.
7. June 2022/by Black resist
For a surprisingly high number of applications, it is important to disable the transparency of the substrates completely, while still having the option to generate structures.
1. June 2022/by Bleachable resists
The basic idea behind dyed resists developed within the scope of the Photoenco project (June 2016 - May 2019) was that dyes are mixed into the polymer matrix of the resist which then either change their colour or become colourless upon irradiation.
9. July 2018/by AllAdminCAR 44 on copper
If negative photoresist CAR 44 (AR-N 4400) is directly used on copper or copper-containing substrates, the following points must be observed.
11. July 2017/by AllAdminChemically enhanced negative resist (Process parameters and resolution)
Process parameters, sensitivity, resolution, edge quality and dimensional stability are exemplarily shown for AR-N 4340. Investigations were performed on 150mm-wafers with Si-surface.
9. July 2013/by AllAdminChemically enhanced negative resist without cross-linking
In some applications, the substrate on which the negative resist is to be applied cannot be heated. This may be the case for sensitive glass and especially for very big substrates.
11. May 2022/by Coloured negative photoresists
Allresist now also offers colored negative resists with the designation SX AR-N 8500. The difference to FUJIFILM resists is that only dyes and no pigments are dissolved in the resists. This allows to achieve a high resolution and high edge sharpness.
11. October 2017/by AllAdminDevelopment of thick negative resist layer
If the negative resist AR-N 4400-50 is utilised, resist layers of >200 µ m can be built up in repeated coating steps (see product information of CAR 44). Decisive for the quality of the layers to be obtained is the bake procedure.
7. October 2013/by AllAdminDilution of resists
Almost all photo resists contain PMA (PGMEA) as a solvent. This solvent is therefore the most common thinner and offered by us as AR 300-12 angeboten. The PMA is often used for the removal of edge beads.
25. May 2022/by Dose-dependent structure size with negative resists
The desired structure size also largely depends on the exposure dose used. In the case of overexposure, structures begin to widen which is particularly pronounced during laser exposure.
20. May 2015/by AllAdminEthanol and toluene-resistant photoresist AR-U 4060
Structures of the image reversal resist AR-U 4060 show an increased resistance against organic solvents after flood exposure with subsequent tempering. Ethanol and toluene attack normal positive resist layers quickly, which are consequently dissolved in short time.
21. July 2015/by AllAdminFabrication of vertical flanks with CAR 44
AR-N 4400-50 was investigated at the TU Braunschweig with particular regard to the fabrication of well-defined resist architectures with vertical flanks.
20. January 2017/by AllAdminFluorescent resist structures with photoresists
Photoresists can also be used to incorporate fluorescent dyes. Particularly negative-tone photoresists are of interest in this regard, since the use of selected fluorescent dyes allows defining an adjustable emission in variable wavelength ranges. Resist layers with violet, blue, yellow, orange, or red fluorescence were produced by embedding the respective dyes into the negative-working Atlas 46 S resist.
25. April 2018/by AllAdminGeneral: Resist composition
The resists most widely used by far are the positive photo resists, followed by negative photo resists. However, there are other special resists as well.
Image reversal resists are positive resists with an additional amine. Depending on the manufacturing process, positive or negative images can be generated.
1. June 2022/by Image reversal resists are positive resists with an additional amine. Depending on the manufacturing process, positive or negative images can be generated.
Generation of undercut structures with negative resists
With laser direct exposure, a slight undercut of the structures can be generated: The upper part of the layer is more strongly irradiated due to the absorption of the resist and consequently more intensely crosslinked.
20. May 2015/by AllAdminLaser ablation of PPA (Phoenix 81)
PPA layers can also be structured by laser ablation. Substrates coated with AR-P 8100 were structured with pulsed laser light at different wavelengths at the IOM Leipzig (Dr. Klaus Zimmer). In this process, architectures with very little edge roughness could be generated. In the absorption range of PPA, at 248nm, complete ablation was achieved without damaging the silicon substrate.
7. June 2022/by Laser direct exposure with AR-P 3540
In addition to a structuring with photomasks which is frequently used in lithography, is it also possible to write the structures directly, i.e. without masks, with laser beams.
13. June 2014/by AllAdminLift off (one layer – two layer)
Two procedures are principally possible to manufacture e.g. conducting paths: 1. Etching technique: A thin metal film (e.g. aluminium) is deposited on a wafer (evaporation or sputtering)
13. July 2012/by AllAdminNegative CAR PMMA resist SX AR-N 4810/1
The principle of chemical amplification could successfully be transferred to PMMA polymers. The new special resist SX AR-N 4810/1 is a chemically amplified photoresist based on PMMA that can be developed anhydrously with organic solvents – a crucial property in the case of moisture-sensitive substrates.
20. May 2015/by AllAdminNegative poly(hydroxystyrene) and (hydroxystyrene-co-MMA) photoresist with high-temperature stability
As an alternative to the polyimide negative resist, SX AR-N 4340/6 was developed, a highly sensitive CAR negative resist based on polyhydroxystyrene, which can be developed under aqueous-alkaline conditions.
13. January 2022/by Negative polyimide photoresist
As an alternative to the positive polyimide resist (SX AR-PC 5000/82.7) which is already a polyimide in dissolved form and thus requires no curing process (see "Positive polyimide resist")
27. February 2013/by AllAdminNegative two- layer lift-off system
Positive two-layer systems have been on the market for a long time (see positive two-layer lift-off systems). Now there are also versions with negative resists as top resist. The greatest advantage of this innovation is the higher thermal stability of negative resists.
9. July 2013/by AllAdminNew procedure for the spray coating of deep topologies with SX AR-P 1250/20
In the CiS Institute for Microsensors, deep silicon etch grooves are structured for the fabrication of customer-specific components. For this purpose, a coating procedure via spray coating was developed.
27. February 2013/by AllAdminNIR-laser structurable photoresists
By adding suitable dyes to negative-working CAR resists, even a patterning beyond the usual wavelength range is possible if pulsed lasers with sufficiently high intensity are used for exposure.
27. October 2014/by AllAdminOne-layer and two-layer lift-off
Lift-off structures are needed for many technologies. There are one-layer and two-layer processes. For one-layer, only one resist is used. Typical examples are negative resists, see Resist-Wiki "Generation of undercut structures with negative resists". However, there are also positive resists (AR-P 5300) for the lift-off. There is only a slight difference, though in most cases, which, however, is sufficient for many procedures.
24. May 2022/by Photoresist coatings on Teflon substrates
Teflon or similar products are, due to their extreme surface properties, utilised for applications in which a structuring of the Teflon is sometimes desirable. The hydrophobic surface properties however impede the coating with resist,
27. February 2013/by AllAdminPolyimide two-layer systems
In certain applications it is desirable to keep the original properties of a polymer unchanged, e.g. without addition of light-sensitive components like for example for a use as moisture sensor.
31. August 2012/by AllAdminPositive polyimide one-layer resist
Polyimides are produced by polycondensation of tetracarboxylic dianhydrides and diamines. For highest thermal strain only polyimides are suitable which contain aromatic building blocks in the polymer chain.
27. February 2013/by AllAdminPositive resist for temperature sensitive substrates
In many cases, substrates meant to be structured may not be heated above 50 – 70 °C. These can be glass partitions which distort at higher temperatures and thus might lose their size accuracy. However, some organic polymers which are to be coated are temperature sensitive. Moreover, thermosensitive structures may already exist on the substrates.
12. May 2022/by Positive two- layer lift-off system
These systems have a bottom resist that is not photosensitive but soluble in alkali. The polymers must be composed in such a way that the lacquer coat withstands a coating with a photoresist with the solvent PMA (PGMEA) without any problems. Otherwise there would be a mixing of both resist layers.
14. June 2022/by Ready-to-use spray resists with EVG devices (positive and negative)
Spray coating is often used for the coating of complex topologies. There are various manufacturers of spray coating equipment, probably the best known are EV Group and Süss Microtec. Both producers use different strategies and devices for spraying, and therefore ready-to-use spray resists must be adjusted for the particular equipment.
31. May 2022/by Resist for 488 nm exposure wavelength
General exposure wavelengths for broadband UV-lithography are in a range between 300 nm and 450 nm, which includes the important lines of high-pressure mercury lamp at 436 nm (g-line).
31. August 2012/by AllAdminResist for near infrared (NIR)
With the development of photoresists for an exposure in the wavelength range of 500 to 1100 nm using laser light, new procedures became possible. Lithographic processes at an exposure wavelength greater than 480 nm are not possible with standard photoresists.
16. July 2012/by AllAdminSensitive negative PMMA resist (CAR)
PMMA resist are mainly used for electron beam applications or as protective coatings in aggressive wet chemical etching procedures. In principle, also a structuring of PMMA layers with deep UV exposure (220-266 nm) is possible, but the sensitivity is in this case low and long exposure times are consequently required.
27. October 2014/by AllAdminSensitive negative resist for 405 nm laser direct exposure
Negative resist AR-N 4400-10 can be structured with laser direct exposure at an exposure wavelength of 405 nm. Different arrays are shown in the figure.
20. May 2015/by AllAdminSpray resists for different topologies (negative)
Allresist furthermore offers various negative-tone resists for spray coating applications which are described in detail in this section (see Spray resists for different topologies (positive and negative)
31. August 2012/by AllAdminSpray resists for different topologies (positive and negative)
Spray resists available to date (AZ 4999) are designed for extreme topologies, which means that even vertical silicon trench sidewalls can be covered with resist. These excellent features however come at a price:
31. August 2012/by AllAdminStructuring by ablation of the resist materials
The basic principle of laser ablation is that laser irradiation of a certain wavelength introduces so much energy into the resist material which is modified for ablation that the resist polymer is destroyed and then vaporizes as low molecular weight fragments.
9. July 2018/by AllAdminStructuring of polyphthalaldehydes with photolithography
PPA layers are sensitive to light and can thus be structured directly by photolithography. Irradiation with light of wavelengths < 300 nm (Hg vapour lamp) results in a cleavage of the polymer chains and the formation of volatile components that partly begin to evaporate even at room temperature.
21. July 2015/by AllAdminSurface imaging resist system SX AR-N 7100 – silylable photoresist
The negative photoresist experimental sample SX AR-N 7100 is a surface imaging and dry developable system. With this system, structures can be transferred into thick resist layers by means of plasma etching.
4. July 2016/by AllAdminTemperature-stable negative resist
New aqueous-alkali soluble polymers may even outperform novolacs in certain features. Standard novolacs generally melt in a range between 115–130°C. The thicker the resist film, the higher is the impact of this feature on the resist structure.
16. July 2012/by AllAdminThermally stable two-layer lift-off systems
The Resist Wiki article "Positive two-layer lift-off systems" describes the principle of these two-layer systems. During the application of lift-off structures, temperatures above 150 °C occur frequently, for example during sputtering. If the usual photo resists are used as top layer, the lift-off structure melts and thus becomes useless for the process.
25. May 2022/by Thermostable photoresists
Many applications demand coatings with excellent thermal stability. Structures of the temperature-stable negative resist SX AR-N 4340/6 are able to withstand temperatures of up to 350 °C with high shape accuracy
27. October 2014/by AllAdminTop surface imaging (TSI) photoresist – principles
Roland and Coopmans intensively studied the fundamentals of the top surface imaging technology which is based on a selective resist silylation process (DESIRE process). A positive photoresist specifically optimised for this purpose with considerably increased content of light-sensitive components (LSCs) is exposed image-wise.
19. May 2022/by Two-layer photoresist system for water-sensitive substrates
If contact of a substrate with water must be avoided during the patterning process, a two-component photoresist system composed of PMMA resist (bottom layer) and photoresist (top layer) offers an alternative to SX AR-N 4810/1.
21. July 2015/by AllAdminTwo-layer resist system for hydrofluoric acid etching
Hydrofluoric acid etchings, even those in highly concentrated acids (48%), are technologically used despite the high risk involved with HF applications.
16. July 2012/by AllAdminUV-structuring of PMMA resists
PMMA resists can also be patterned using UV-lithography, but only at exposure wavelengths of 200 – 270 nm (deep UV light). Typically used is the wavelength-range of the lowest line of high-pressure mercury lamps at 254 nm.
31. August 2012/by AllAdminWater-based resists
The majority of photoresists is almost exclusively soluble in organic solvents like e.g. PGMEA (propylene glycol methyl acetate, German: PMA). But there are exceptions.
27. October 2014/by AllAdminWaterfree developable special resist SX AR-N 4810/1
The new special resist SX AR-N 4810/1 is a chemically enhanced photo resist based on PMMA, which can be developed waterfree – crucial in the case of moisture-sensitive substrates – with organic solvents.
19. May 2022/by All 80 /Adhesions Promoter 0 /Allresist 0 /AR NEWS 0 /Basic Chemistry 0 /Basics 0 /Bottom Resist 0 /Developer 0 /E-Beam Resist 0 /FAQ 11 /FAQ 0 /General 0 /General 13 /General 0 /General 0 /Home 0 /Home Resist 0 /Negative 12 /Negative 0 /News 0 /Newspaper Article 0 /Other Resists 0 /Other Resists 15 /Photoresist 0 /Positive 0 /Positive 29 /Press 0 /Process Chemicals 0 /Process Information 0 /Process Procedures 0 /Protective Resist 0 /R&D 0 /R&D Projects 0 /Remover 0 /Resist of the month 0 /Resist Wiki 0 /Scientific Article 0 /Stopper 0 /Thinner 0 /z-SX-AR-PC 5000/41 0 /z_AR 300-12 0 /z_AR 300-26 / 300-35 0 /z_AR 300-40 0 /z_AR 600-01 - 09 0 /z_AR-N 4400 0 /z_AR-N 4600 0 /z_AR-P 3100 0 /z_AR-P 617 0 /z_AR-P 6200 0 /z_AR-P 630-670 0 /z_AR-P-8100 0 /z_AR-PC 5090/91 0 /z_SX AR-N 8200 0 /z_SX AR-P 3500/8 0
1. What are e-beam resists composed of, and how do they work?
E-beam resists (electron beam resists) are designed for electron beam and deep UV applications for the fabrication of highly integrated circuits, mainly for mask fabrication. They are employed in electron beam direct writing and multilayer processes.
23. August 2008/by AllAdmin10. How high is the etch resistance of e-beam resists in the presence of strong acids?
Concentrated oxidising acids (sulphuric acid, nitric acid, aqua regia 1) , piranha 2) ) attack resist films already at room temperatures and are often used as remover for persistent resist structures.
14. August 2008/by AllAdmin11. How high is the solvent resistance of e-beam resist films?
With respect to the source materials used, e-beam resists fall into two different categories: PMMA resists (AR-P 6000) Novolak resists (AR-N/P 7000) » The general rule is that with increasing bake-
13. August 2008/by AllAdmin2. For how long are e-beam resists stable, and what are the optimal storage conditions?
PMMA- and copolymer e-beam resists are not light-sensitive in the visible UV range, they consequently don’t react to light exposure (no safe yellow light required) and are substantially less temperature-
22. August 2008/by AllAdmin3. What is the optimal pre-treatment of substrates for e-beam resist application?
If new and clean substrates (wafers) are used, a bake at approximately 200 °C for a few minutes is sufficient in order to dry the substrates, which however then have to be processed quickly.
21. August 2008/by AllAdmin4. How high is the adhesion strength of e-beam resists to different wafers?
Adhesion between substrate and coating is a sensitive feature of a resists, which is also true for e-beam resists. PMMA- and copolymer resists are however significantly less prone for adhesion problems than e-
20. August 2008/by AllAdmin5. How are e-beam resists exposed? How can the optimum exposure dose be determined?
By using very short-wavelength electrons for the exposure of the resists, an excellent resolution of up to 2 nm can be achieved (spot beam). Exposure is carried out by conventional e-beam equipment following the principle of direct writing or shaped beam procedure.
19. August 2008/by AllAdmin6. Which developers are optimal for e-beam resists, and how do factors like developer concentration and temperature influence the result?
During development, a positive tone resist film is patterned by a removal of exposed areas, while unexposed areas are removed when negative resists are used. To achieve reproducible results,
18. August 2008/by AllAdmin7. How can e-beam resist films be removed again?
For the removal of all e-beam resist coatings baked at lower temperatures (softbake), polar solvents may be used such as e.g. the recommended thinner AR 300-12 or AR 600-01, 600-07,
17. August 2008/by AllAdmin8. Which resolutions do e-beam resists achieve?
With respect to the achievable resolution, purely academic resolution values and industrially utilisable values represent two quite different aspects. Theoretically, resolutions of 2 nm are possible (single electron spot)
16. August 2008/by AllAdmin9. How high is the plasma etch resistance of e-beam resists?
Electron beam resists of the AR 6000 and AR 7000 production line display quite different etch resistance features in dry etch processes such as e.g. argon sputter and CF 4 . Novolak-
15. August 2008/by AllAdminAR-N 7700, 4 µm thick, proximity effect
The general aim of electron beam lithography is to achieve a maximum resolution, and therefore mostly very thin layers are used (50 - 500 nm). In a few cases however also very small structures with high aspect ratio are of interest.
27. February 2013/by AllAdminAR-P 617 Two layer lift-off system
An alternative version of the structure of two layer systems emanates from only one resist: AR-P 617 (PMMAcoMA 33). At increasing temperature, AR-P 617.08 becomes linearly more sensitive.
22. March 2022/by Atlas 46 for e-beam lithography
A new application field for Atlas 46 is electron beam lithography, as experiments with a thin Atlas resist layer patterned by e-beam lithography demonstrated. At a layer thickness of 450 nm, 200 nm lines were written into this layer. The sensitivity was 70 μC/cm² at an acceleration voltage of 100 kV.
12. October 2018/by AllAdminBasics
Information on:
Polymer resists (layer builders)
Photosensitive components
Cross linker
Other resist components (adhesion promoter, tenside, solvent, colorant)
Process information such as: Cleaning of substrates, adhesive strength, dilution of resists, yellow light, softbake, rehydration, exposure and storage
Process procedures such as: Lift-off procedures, wet-chemical etching, dry-chemical etching, UV-curing, lithographic procedures and stabilization/curing of resist layers
See Photo resists: General
8. June 2022/by Polymer resists (layer builders)
Photosensitive components
Cross linker
Other resist components (adhesion promoter, tenside, solvent, colorant)
Process information such as: Cleaning of substrates, adhesive strength, dilution of resists, yellow light, softbake, rehydration, exposure and storage
Process procedures such as: Lift-off procedures, wet-chemical etching, dry-chemical etching, UV-curing, lithographic procedures and stabilization/curing of resist layers
See Photo resists: General
BOE etching of SiO2 with CSAR 62 mask
Even the highly sensitive e-beam resist CSAR 62 can be used as mask for an etching process with HF (BOE, 10:1).
13. April 2016/by AllAdminCAR 44 for e-beam lithography
We now succeeded in finding a remarkable solution for high-layer e-beam structuring. The negative resist CAR 44 (AR-N 4400-10) was coated to yield a layer with a height of 9.5 μm, dried, and irradiated.
12. October 2018/by AllAdminChemically amplified, highly sensitive negative e-beam resist SX AR-N 7730/37
With SX AR-N 7730/37, we present a new negative CAR e-beam resist. This resist possesses a very high sensitivity with at the same time high process stability.
13. June 2014/by AllAdminCollapse of extreme high-resolution e-beam resist structures
A typical problem arising from an extreme resolution at an aspect ratio of > 10 is the collapse of bar structures. In Fig. 1, 10-nm bars with a pitch of 50 nm are displayed. These structures were realised with CSAR 62 (SX AR-
27. February 2013/by AllAdminConductivity under the application conditions of e-beam lithography
The measured conductivity of resist layers is strongly influenced not only by the temperature but also directly dependent on the air humidity. After a softbake, the now almost anhydrous layer gradually takes up water at room temperature from the ambient air due to the slightly hygroscopic properties of the polymer.
5. October 2015/by AllAdminCSAR 62 Avoidance of particles during large-area exposures
During the exposure and subsequent development of large structures (> 1 µm), occasionally particles are deposited on fully developed surfaces
27. October 2014/by AllAdminCSAR 62 for EUV applications
In addition to the use in e-beam lithography, the highly sensitive e-beam resist CSAR 62 can also be structured by exposure to UV radiation since the resist strongly absorbs UV radiation in the wavelength range of 190 – 240 nm.
13. April 2016/by AllAdminCSAR 62 for thick films
Layers with a thickness of 1.5 μm were produced using AR-P 6200.18, thick. As shown by investigations at the KIT (IMT, Dr. Lothar Hahn), allows this layer thickness to generate very regular trenches with a width of 300 nm at a period of 300 nm (see Fig. 1).
11. October 2017/by AllAdminCSAR 62 lift-off for thick layers
For special applications in which metal layers with a thickness of a few hundred nanometres are to be generated by lift-off techniques, accordingly higher layers are needed.
27. October 2014/by AllAdminCSAR 62 nanostructures written at 100 kV
Applying an acceleration voltage of 100 kV has the advantage that the proximity effect due to electron backscattering can be avoided.
14. March 2022/by CSAR 62 single layer lift-off system
With our new development e-beam resist AR-P 6200 (CSAR 62), very fine structures like e.g. 10 nm wide trenches can be manufactured with very high contrast (> 14) and comparably high sensitivity.
25. April 2018/by AllAdminCSAR 62 thick layers
Intense plasma etchings for the generation of deep etch structures however require significantly thicker resist layers and place special demands on resolution and contrast.
27. October 2014/by AllAdminCSAR 62 – Development at low temperatures
The sensitivity of CSAR 62 is strongly influenced by the choice of the developer. In comparison to the standard developer AR 600-546, the sensitivity can be increased almost tenfold if AR 600-548 is used instead.
5. October 2015/by AllAdminCSAR 62 – Experimental studies on new, sensitive developers
CSAR 62 layers can also be patterned by intensive exposure to UV light. Irradiated films were in this experiment developed with different solvents and the observed sensitivities were compared with each other.
5. October 2015/by AllAdminCSAR 62 – Mechanism of action
By comparison with PMMA resists, CSAR 62 is characterized by a higher sensitivity and a significantly better plasma etch resistance. The main components of the resist are poly(α-methylstyrene-co-chloromethacrylic acid methyl ester), an acid generator and the safer solvent anisole. The higher sensitivity results from the addition of halogen atoms to the polymer chain.
24. May 2022/by CSAR structures on glass
The use of a combination of CSAR 62 and the conductive coating Electra 92 in e-beam lithography allows the manufacture of highly complex structures on insulating glass or semi-insulating substrates such as e.g. gallium arsenide.
5. October 2015/by AllAdminDiffractive optics with the “analogous“ e-beam resist
Allresist designed an e-beam resist which produces, depending on the respective exposure dose used, a three-dimensional resist profile.
27. February 2013/by AllAdminE-beam resist: Procedures
There are both mask-based and maskless writing procedures in electron beam lithography. More up-to-date systems use defined beams with, by the application of masks, selectively adjusted geometrical cross sections or respectively profiles, which are deflected upon the various positions (vector scan mode).
9. June 2022/by E-beam resists: General
Electron beam lithography is a special procedure for the structuring of electron beam sensitive resist layers in order to produce microelectronic circuits and photomasks used in photolithography.
8. June 2022/by Electra 92 variant optimised for applications on novolac-based resists
Novolac-based e-beam resists have other surface properties than e.g. CSAR 62, PMMA, or HSQ resists. Due to a higher solvent content of the conductive resist as for example is the case with SX AR-PC 5000/90.2, these novolac-resists are already moderately attacked.
5. October 2015/by AllAdminElectron beam lithography systems
Significant components of electron beam lithography systems are the electron source, the electro-optical system and the focusing system (deflection or respectively projection unit). Hot cathodes are used for equipment with lower resolution, devices with higher resolution, however, preferably need thermic field emission sources.
9. June 2022/by Electron beam resists
Among the first resists used (since about 1980) and still applied in many cases are short-chain (50.000 g/mol (50k)) as well as long-chain (950.000 g/mol (950k)) poly(methyl methacrylate) (PMMA resist, sensitivity at 100 keV approximately 250 – 500 µC/cm2).
13. June 2022/by Evaluation of various developers for e-beam exposed CSAR 62 layers (100 kV)
To evaluate the suitability of various developers for CSAR 62, Dr. Lothar Hahn (Karlsruhe Institute of Technology (KIT), Institute of Microstructure Technology) kindly provided various substrates which had previously been exposed to 100 kV e-beam irradiation (dose variations).
4. July 2016/by AllAdminFluorescent resist structures
Fluorescence is the spontaneous emission of light briefly after a substance is excited by electronic transitions. The emitted light has usually less energy than the previously absorbed light.
11. October 2017/by AllAdminGeneration of secondary electrons
Alongside the occuring elastic scattering effects at a collision with other electrons or atoms, incoming primary electrons can also be scattered inelastically when entering or traversing resist layers.
9. June 2022/by HF etching of GaAs with CSAR 62 masks
Mr. Y. Nori from Lancaster University (Department of Physics, UK) could very successful generate structures for the production of photonic crystals with CSAR 62.
13. April 2016/by AllAdminHigh resolution on quartz with Electra 92 on HSQ resists
An accurate patterning on quartz substrates is not possible without the use of a conductive coating. Investigations of the company Raith GmbH demonstrated that an HSQ resist XR1541 on a quartz substrate can be patterned with very high quality after coating with Electra 92.
21. July 2015/by AllAdminHigh-resolution negative e-beam resist
A process-stable, sufficiently sensitive e-beam resist with a resolution of about 30 nm is urgently needed to accelerate the progress in electron beam lithography.
13. July 2012/by AllAdminHigh-resolution negative e-beam resist AR-N 7520.17new for etching application
Very even and smooth 300nm ridges could be achieved with AR- 7520.17new and a coating thickness of 400nm.
2. March 2022/by High-resolution PMMA one layer resist
Utilizing SX AR-P 640/2 (PMMA 90K) as one layer system, an even higher resolution can be achieved if process parameter are varied, in particular the exposure dose.
31. August 2012/by AllAdminHighly sensitive e-beam resist AR-P 617 (PMMA-copolymer)
The copolymer composed of methyl methacrylate and methacrylic acid is, in contrast to the pure PMMAs, able to form a 6-membered ring during thermal loading.
13. April 2016/by AllAdminLoading
A part of the high-energy electrons which impact on the substrate is stopped and cannot be conducted at all or only very slowly toward ground, especially in the case of insulating substrates such as quartz. The substrate and respectively the resist charges itself negatively and the electron beam is deflected uncontrollably from the desired position during exposure.
23. May 2022/by Long-term stability of Electra 92
To assess the long-term stability of Electra 92 (SX AR-PC 5000/90.2), two reference samples were coated on glass (300 rpm, 3 min, softbake at 85 °C for 30 min in the oven) after different storage times of 15 months and 3 months, respectively (refrigerator, 8 °C).
5. October 2015/by AllAdminManufacture of plasmonic nanostructures with CSAR 62
These nanostructures may e.g. serve as optical antennas for the detection of single molecules. To avoid the undesirable charges on the quartz substrate, Electra 92 was used successfully.
5. October 2015/by AllAdminMedusa 82 for EUV applications
For an optimum handling of EUV lithography using the RWTH system, a sensitivity range of 30-40 mJ/cm² is desired. A Medusa 82 sample supplemented with 2.5 % photoacid generator (PAG) already reached this target range. These investigations will be continued within the scope of a research project.
12. October 2018/by AllAdminMedusa 82 with photoacid generator (PAG)
One disadvantage of HSQ and Medusa 82 is the comparably low sensitivity, which can however be increased by an addition of photoacid generators.
12. October 2018/by AllAdminMedusa 82 – the alternative to HSQ-resists, storage stability
Our research team successfully developed a negative resist with high resolution and plasma etching stability in oxygen: Medusa 82. Already with the first samples, it was possible to achieve the properties of HSQ.
9. July 2018/by AllAdminMedusa 82: Influence of post exposure bake (PEB)
The addition of photoacid generators (PAGs) can significantly increase the sensitivity of Medusa 82 (see Resist Wiki “Medusa with photoacid generator”). Another option is to add a PEB after e-beam exposure. Even if substrates were previously stored for several days, the sensitivity significantly increases depending on the temperature and the duration of the PEB.
12. October 2018/by AllAdminPatterning of the conductive protective coating Electra 92
A negative resist (e.g. AR-N 4340) is coated onto the substrate, exposed, and developed. The exposure dose should be chosen as small as possible to provide the desired slight undercut which supports the later lifting.
21. July 2015/by AllAdminPhoenix 81 – Storage conditions and dispatch
In the final stage of the Eurostar PPA-Litho project which was aimed to develop the resist Phoenix, we achieved to generate far more stable PPA polymers by optimizing the synthesis procedure. Pure polyphthalaldehydes which were subjected to a “stress test” for 14 days at 37 °C showed no decomposition. These resists can thus be shipped without cooling; this however only applies to pure PPA polymers.
9. July 2018/by AllAdminPMMA e-beam resist with flat gradation for three-dimensional structures
It is advantageous for the fabrication of three-dimensional structures if the gradation (contrast) is low. A resist with very high contrast will always generate perpendicular resist flanks. Smallest changes of the dose induce a rapid shift from undeveloped to the completely developed state. If the gradation is low, the dose difference between the undeveloped and the completely developed state is accordingly high.
21. March 2022/by PMMA e-beam resist, positive and negative in the case of overexposure, suitable for bridge structures
PMMA resists work positively under standard conditions. The long polymer chains are broken into small fragments by the irradiation process. PMMA 950k with a molar mass of 950 000 g/mol is primarily reduced to a molar mass of about 5000 g/mol. These short-chain polymers are readily soluble in the developer, which is not the case for the polymer with the initial high molar mass.
21. March 2022/by PMMA lift-off structures on semi-precious stone substrates using Electra 92
Semi-precious stones like sapphire or garnet increasingly gain in importance as substrates for semiconductor industry. Even though these materials have insulating properties, a patterning with electron beam lithography is nevertheless possible with the help of Electra.
5. October 2015/by AllAdminPoly(phthalaldehyde)-based electron beam resists
A direct positive patterning of PPA layers is possible by electron bombardment. Similar to the irradiation of normally used e-beam resists like e.g. CSAR 62 or PMMA, the electron beam causes a fragmentation of the polymer chains.
21. July 2015/by AllAdminPoly(phthalaldehyde)-based electron beam resists, University of Tübingen
A direct positive patterning of PPA layers is possible by electron bombardment. Similar to the irradiation of normally used e-beam resists like e.g. CSAR 62 or PMMA, the electron beam causes a fragmentation of the polymer chains.
27. July 2022/by Positive polyimide resist for e-beam-lithography
First experiments with our SX AR-P 5000/82.7 using e-beam lithography clearly demonstrated that this resist can easily be patterned which offers the possibility to generate nanostructures which are thermally stable up to 350 °C.
13. July 2012/by AllAdminPPA for two layer applications
Report on the two layer system, respectively lift-off: AR P-617 (250nm) with PPA (30nm), development followed by vapor coating of Al (40nm).
22. March 2022/by Proximity effect
A part of the high-energy electrons which impact on the substrate is stopped and cannot be conducted at all or only very slowly toward ground, especially in the case of insulating substrates such as quartz. The substrate and respectively the resist charges itself negatively and the electron beam is deflected uncontrollably from the desired position during exposure.
7. June 2022/by Raster and vector scan principle
Raster scan principle is a procedure in which the electron beam is led line by line over the exposure area, comparable to the beam guidance in an electron microscope. The structures are exposed by switching the electron beam on and off while continuously moving the substrate (XY regulation).
7. June 2022/by Ratio resolution and dose, exemplarily shown for e-beam resist SX AR-N 7530/1
Process-stable negative resist systems which allow resolutions of < 30 nm with sufficiently high sensitivity are of growing interest for applications in electron beam lithography.
13. June 2014/by AllAdminResists for novel applications in lithography – thermally structurable polymers
Within the scope of the Eurostar project PPA-Litho, Allresist currently evaluates innovative high-quality resists on poly(phthalaldehyde) (PPA) basis in cooperation with the company Aglycon, the Joanneum Research in Weiz, and the SwissLitho AG in Zurich.
21. July 2015/by AllAdminSCALPEL
A further mask-based technology is SCALPEL (Scattering with Angular Limitation Projection Electron-beam Lithography). Due to the interposed mask, certain parts of the electron beam are shadowed. The scattering layer strongly deflects incident electrons. A great advantage of this procedure as compared to electron absorption is less loading and less heating of the mask.
7. June 2022/by Scattering
If an electron beam with high energy is channeled onto a resist layer (5- 100 keV), forward scattering ( 90° in direction of arrival). The deflection causes the electron beam to widen, thus reducing resolution.
8. June 2022/by Sensitive, etch-stable negative e-beam resist for processes without yellow light
The success story of electron beam lithography began in the 1980th with the development of the first PMMA resists. These resists are absolutely light-insensitive in the UV-wavelength range above 300 nm.
13. July 2012/by AllAdminSolution
In contrast to photolithography, the solution of e-beam lithography is practically unlimited by wavelength. Electrons of an energy of 25keV have a wave length of < 0,01 nm. The maximum resolution thus is crucially determined by the beam diameter.
23. May 2022/by Solvents in e-beam resists
The beginning of electron beam lithography dates back to the early 1980s when the first PMMA resists were developed, with chlorobenzene as first solvent. This solvent most efficiently dissolves the various PMMAs (with different molecular masses of 50K to 950K)
9. July 2013/by AllAdminT-gates with three-layer system CSAR/PMMAcoMA/PMMA
T-gate structures are often required for the fabrication of electronic components (MEMS, HEMTs). Corresponding nanostructures can be realized via e-beam lithography in multi-layer processes. Generally, resist layers with different sensitivities like e.g. PMMAs with varying molecular weight distributions are coated on top of each other, irradiated with electrons and then developed in one step.
8. June 2022/by Temperature resistance of e-beam polymers
Layers and structures of e-beam polymers possess different temperature resistance properties. PMMA layers are generally the most stable.
15. March 2022/by Thick CSAR 62
A few applications like e.g. the manufacture of deep etched structures by plasma etching require a processing of thick resist layers. Of major importance in this case is a high sensitivity, especially in electron beam lithography.
13. June 2014/by AllAdminThree-layer system CSAR/PMMAcoMA/PMMA
A further variant for the structure of three-layer systems uses 950k PMMA as bottom resist, AR-P 617 as middle layer and CSAR 62 as top resist. There is no mixing during the coating, thus ensuring a defined layer buildup. AR-P 617 can be coated on all PMMA’s (50k – 950k) without any problems, besides, the coating with AR-P 6200 (CSAR 62) is successful as well since anisole does not dissolve AR-P 617.
9. June 2022/by Top Surface Imaging E-Beamresist
The DESIRE process can also be used for electron beam lithography even though certain differences exist between photo and e-beam lithography. Structures are written into the resist layer by means of electrons.
3. February 2017/by AllAdminTwo-layer PMMA e-beam resist system for high-resolution lift-off
For the lift-off of high-resolution structures in a two-layer process, PMMA resists (90K and 200K) were adjusted to yield a film thickness of 90 nm to 100 nm. This resist system is particularly well suited for the fabrication of sub-
21. September 2012/by AllAdminUse of CSAR 62 for the manufacture of nanostructures on GaAs substrates
CSAR 62 is routinely used to produce innovative quantum devices at the TU Delft (Mr. Toivo Hensgens, TU-Delft, the Netherlands). For the structures shown below, a 72 nm layer of CSAR 62 was exposed to 100 kV and then developed with amyl acetate.
4. July 2016/by AllAdminUtilising Electra 92 for SEM applications
The coating with Electra 92 on highly electrically insulating polymers or also on glass allowed a high-quality imaging of nanostructures in SEM.
13. April 2016/by AllAdminWriting time
The minimum necessary exposure time for a certain area, at a given exposure dose, can be calculated by the following correlation: Area * dose = Duration of exposure * beam current.
8. June 2022/by Black-Protect – stable protective coating for HF and KOH etchings
Allresist offers the protective coating SX AR-PC 5000/40 for HF and KOH etchings already for a few years. Layers of 5 μm are able to withstand a 48 % hydrofluoric acidic solution for several hours. Also 40 % KOH solutions for silicon etchings do not attack the layer.
9. July 2018/by AllAdminImproved protective coating SX AR-PC 5000/31
Protective coatings are in most cases composed of novolacs or PMMA polymers. Both polymers ensure a sufficiently high protective effect against mechanical damages as well as sufficiently high resistance against acidic solutions.
13. June 2014/by AllAdminPMMA protective coating: reduction of cotton candy effect
Since problems may occur when PMMA protective coatings are applied, new ideas emerged how to optimise the coating properties of these resists. So far, protective coatings tend to show under certain circumstances the so-called "cotton candy effect" during spin coating, which means that fine PMMA threads are formed.
27. October 2014/by AllAdminProtective coating as spray resist for the smoothing of surfaces
PMMA layers (novolak layers) feature an extremely smooth surface. A surface roughness of less than 2nm was measured on resists which were thus optimized. This characteristic can be used for the smoothing of glass surfaces, for instance.
22. March 2022/by Protective coating for KOH-etching
Protective coatings AR-PC 503 and 504 are able to withstand the presence of 40%, 85°C warm KOH for several hours. The polymer PMMA is not attacked under these conditions. These resists can consequently be used to protect front and back surface of wafers during deep silicon etching.
16. July 2012/by AllAdminProtective coating to prevent mechanical damage
Sensitive substrates can be protected against damage during handling with resist SX AR-PC 5000/3.1, which is especially important in the case of double-sided procedures.
4. October 2016/by AllAdminSafer solvent PMMA protective coating
The protective coatings AR-PC 503 and AR-PC 504 have been successfully used for many years in aggressive KOH etching procedures. These resists are traditionally produced with the solvent chlorobenzene.
27. October 2014/by AllAdminSX AR-PC 5060 F-Protect (replacement for Cytop)
The new, highly insulating protective coating SX AR-PC 5060 F-Protect represents a good alternative to the well-known resist Cytop®.
15. January 2018/by AllAdmin2L-Lift-off system AR-P 617 – AR-P 8100
Anisole PPA solutions can be coated on PMMAcoMA 33 (AR-P 617). The single layers add up in this case; no mixing of layers occurs, which is a decisive prerequisite to realise defined 2- or also 3-layer systems.
25. April 2018/by AllAdminManufacture of undercut structures for T-gates in three-layer processes
In principle, several options exist to develop three-layer systems for the manufacture of T-gates. It is however crucial in each case that the different resists do not mix during the coating in order to ensure a coherent and well-defined layer build-up. AR-P 617 can be coated onto all PMMAs (50k - 950k) without any problems, since the resist solvent does not attack PMMAs. Vice versa can AR-P 617 also be coated with PMMA solutions in ethyl lactate or also anisole.
29. September 2016/by AllAdminTwo-layer e-beam resist system with novolacs as bottom resist
For multi-layer applications in e-beam lithography, Allresist offers the highly versatile bottom resist AR-BR 5460/5480. The removal rates of the bottom layer can easily be specifically adjusted by slightly changing the softbake temperature and the developer strength.
19. January 2016/by AllAdminUse of PPA in multilayer processes
Anisolic PPA solutions can be coated onto PMMA (600k, 950k), PMMAcoMA (AR-P 617) as well as on bottom resist AR-BR 5480 (alternative to PMGI). The single layers add up in each case, and virtually no mixing takes place. It is thus possible to realize well-defined two- and three-layer systems by these means.
20. January 2017/by AllAdminAll 24 /Adhesions Promoter 3 /Allresist 0 /AR NEWS 0 /Basic Chemistry 0 /Basics 0 /Bottom Resist 0 /Developer 12 /E-Beam Resist 0 /FAQ 0 /FAQ 0 /General 0 /General 0 /General 0 /General 0 /Home 0 /Home Resist 0 /Negative 0 /Negative 0 /News 0 /Newspaper Article 0 /Other Resists 0 /Other Resists 0 /Photoresist 0 /Positive 0 /Positive 0 /Press 0 /Process Chemicals 0 /Process Information 0 /Process Procedures 0 /Protective Resist 0 /R&D 0 /R&D Projects 0 /Remover 6 /Resist of the month 0 /Resist Wiki 0 /Scientific Article 0 /Stopper 1 /Thinner 2 /z-SX-AR-PC 5000/41 0 /z_AR 300-12 0 /z_AR 300-26 / 300-35 0 /z_AR 300-40 0 /z_AR 600-01 - 09 0 /z_AR-N 4400 0 /z_AR-N 4600 0 /z_AR-P 3100 0 /z_AR-P 617 0 /z_AR-P 6200 0 /z_AR-P 630-670 0 /z_AR-P-8100 0 /z_AR-PC 5090/91 0 /z_SX AR-N 8200 0 /z_SX AR-P 3500/8 0
Additional new experimental developers for AR-P 617
For some applications are universal developers of advantage, i.e. developers which are simultaneously well suited for a variety of resist families. Multilayer systems can in this case be developed in one step, and no change of the developer in between is required.
29. September 2016/by AllAdminAdhesion promoter HMDS and diphenylsilanediol (AR 300-80)
The adhesion of resists to different substrates varies. Many substrates like e.g. silicon, silicon nitride and base metals (like aluminium, copper) show generally good resist adhesion features,
28. February 2013/by AllAdminAdhesive strength of AR 300-80
In order to prevent the above described stripping of the PMMA layer from the wafer, the use of adhesion promoters is strongly recommended. Helpful is also a tempering of the wafers at maximum temperature (if possible > 200°C)
7. October 2013/by AllAdminAgeing of developer
Aqueous-alkaline developers are subjected to ageing, due to an uptake of CO 2 from the air. Buffered aqueous-alkaline developers ( AR 300-26, -35 ) are more stable in this respect than developers of the AR 300-40 -series containing TMAH.
13. July 2012/by AllAdminAlkaline developers for aluminium substrates
Some of our customers use alkali-sensitive aluminium substrates. This leads to problems if the metal surface should not be etched in this process.
20. May 2015/by AllAdminAlternatives for NMP-based removers
On September 25, 2009, regulation (EC) No 790/2009 amending EC-GHS regulation (No 1272/2008) on the classification and labelling of substances and mixtures came into force. With this regulation also the new classification of N-
31. August 2012/by AllAdminAqueous-alkaline removers
The simplest but nevertheless highly effective removers are sodium hydroxide (NaOH) and potassium hydroxide (KOH) solutions. Already a 4 % KOH solution will remove basically all novolac-based photo- and e-beam resists within a few seconds.
25. April 2022/by Developer AR 300-35 for alkali-sensitive substrates
The use of aqueous-alkaline developers on alkali-sensitive substrates like aluminium is problematic, because the substrate is similarly attacked during the development step.
27. October 2014/by AllAdminDeveloper for CSAR 62 (AR-P 6200)
For a development of exposed CSAR 62 resist films generally performed by immersion development with development times of approximately 30-60 seconds, developers AR 600-546, 600-548 and 600-549 are well suited.
13. June 2014/by AllAdminDevelopment cascade
The use of a cascade is recommended for optimum performance of the developer and for the highest cleanliness during immersion development. The development often takes place in only one container.
11. July 2017/by AllAdminDevelopment procedures
Developers are designed to remove exposed areas of positive-tone resists and unexposed areas of negative-tone resists without leaving any residuals. The respective other areas of the wafer are ideally not attacked by the developer and remain with a film thickness identical to the initial value.
30. July 2012/by AllAdminEvaluation of various developers for e-beam exposed CSAR 62 layers (100 kV)
To evaluate the suitability of various developers for CSAR 62, Dr. Lothar Hahn (Karlsruhe Institute of Technology (KIT), Institute of Microstructure Technology) kindly provided various substrates which had previously been exposed to 100 kV e-beam irradiation (dose variations).
29. September 2016/by AllAdminNew AR 300-80 and contact angle measurement
In addition to the established adhesion promoter AR 300-80 (which is based on diphenylsilanediol), also other silicone-containing compounds may be used to render hydrophilic surfaces more hydrophobic.
11. July 2017/by AllAdminNew developer for AR-P 5320
In our product information, we recommend developer AR 300-26 for the development of AR-P 5320, our positive photoresist for lift-off applications. A few users however prefer to work with MIF-developers.
20. May 2015/by AllAdminNew developers for AR-P 617
Our highly sensitive e-beam resist AR-P 617 is frequently used in two-layer processes, mostly in combination with PMMA, for the production of lift-off architectures like e.g. T-gates.
13. April 2016/by AllAdminNew developers for PMMAcoMA (AR-P 617, 50 kV)
X AR 600-50/2 is a new, very sensitive and highly selective developer for AR-P 617. The dark erosion is very low even at longer development times. Layers of PMMA or CSAR 62 are not attacked, which is especially important for multi-layer processes.
29. September 2016/by AllAdminNew safer solvent remover AR 300-76
A further new development, the likewise universally applicable remover AR 300-76, is characterized by a much higher flash point of 103°C as compared to AR 600-71.
13. June 2014/by AllAdminNew solvent remover
A new strong solvent remover is able to solve resist layers tempered at room temperature. It is remarkable that the remover takes the same effect on novolak based as well as PMMA based resists and thus is suited for versatile applications. It must be pointed out, however, that the flash point of the remover is below 21 °C and therefore needs to be handled with care.
19. May 2022/by Removers in general
Removers have the task to completely dissolve all resist structures or residues after the respective techonological process step (doting, etching or others) is finished.
30. July 2012/by AllAdminSolvent removers
The classical remover is acetone which is, together with isopropanol, used as cleaning agent in probably every lab worldwide. The dissolving power of acetone for non- or only low-baked films (up to 120 °C) is excellent.
14. April 2022/by Solvents and workplace safety
All resists we offer as well as a large number of process chemicals contain organic solvents. When handling these products, provisions of the Ordinance on Hazardous Substances are to be complied with. The safety data sheets of our products are intended to provide required data and handling recommendations for the user to take effective measures for health protection, workplace safety and environmental protection.
14. April 2022/by Stopper
Stoppers in the classical sense are mainly used for electron beam lithography with PMMA resists. These substances have the function to interrupt the development process after a development of exposed PMMA films and to cleanly rinse off the developer solvent which now contains residual PMMA.
30. July 2012/by AllAdminThinner
Correct dilution of resists (see “Dilution of resists”) Resists are mainly composed of solvents. The majority of photoresists and the negative-tone e-beam resists utilize PGMEA (PMA)
15. August 2012/by AllAdminTypes of developers
There are two main groups of developers: solvent-based and aqueous-alkaline developers. The solvent-based ones are intended mainly for PMMA e-beam resists, for CSAR 62 and also for special polymer based products. In this process, solvents such as methylisobutylketone (MIBK), IPA (partly with water) for PMMA, amyl acetate, MIBK, DEK, DEM, xylol for CSAR 62 and ethylbenzene as well as hexane are used for the protective coating.
14. April 2022/by Quality Promise
Since 1992, we provide our customers with high quality products at moderate prices. Due to an efficient research department and our “close ear“ to the customer, we quickly respond to the needs of the market and consistently offer product innovations.
AR News Newsletter
AR NEWS
Contact
Allresist GmbH
Am Biotop 14
15344 Strausberg
Germany
Tel: +49 3341 – 35 93 0
Fax: +49 3341 – 35 93 29
E-Mail: info(a)allresist.de