Other Resists Archives - Allresist EN https://www.allresist.com/category/resist-wiki/resist-wiki-photoresist/resist-wiki-photoresist-other-resists/ ALLRESIST GmbH - Strausberg, Germany Tue, 07 Jun 2022 10:09:22 +0000 en-GB hourly 1 https://wordpress.org/?v=6.5.2 Laser ablation of PPA (Phoenix 81) https://www.allresist.com/laser-ablation-of-ppa-phoenix-81/ Tue, 07 Jun 2022 10:09:22 +0000 https://www.allresist.com/?p=17456 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.

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Laser 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.

Fig. 1 and 2: 0,5 J/cm2, 248nm, 20ns, double-pulse exposure, 700nm PPA on Si-wafer

Although PPA shows only very little absorption at a wavelength of 355nm, selective ablation with comparatively high sensitivity is still possible. The generated structures again show very smooth edges.

Fig. 3: 0,1 J/cm2, 355nm ps-laser, single-pulse exposure, 700nm PPA on Si-wafer

The laser beam can also be used for the generation of 3d structures. Interference projection through a phase mask allows the  generation of grid structures with sinusoidal course and very little surface roughness.

Fig 4: experimental structure interference projection

Fig. 5 and 6: SEM micrograph of generated PPA grid with sinusoidal course (period ~750nm); 248nm, 20ns pulse, number of pulse: 10, 700nm PPA on Si-wafer

Overview Photoresists- Positive



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]]> ATLAS 46 in general https://www.allresist.com/atlas-46-in-general/ Tue, 07 Jun 2022 09:16:06 +0000 https://www.allresist.com/?p=17445 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.

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ATLAS 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.

The resists consist of poly[(o-cresyl glycidyl ether)-co-formaldehyde] in an organic solvent mixture with the main ingredient 1-methoxy-2-propyl-acetate (PGMEA) and various acid generators. Both resists are developed within a few seconds with the solvent mixtures AR 300–12 or AR 600-70. For a slower and higher-contrast development, AR 600-07 is suitable.

The layer thicknesses of both resists are adjusted to 10 µm at 1000 rpm, further layer thicknesses in the range of 100 nm up to 100  µm are available upon request. It is recommended to softbake on the hot plate at 65° 5 min over 3min ramp at 95 °C for 5 min.

Both resists can be structured by i-line or UV exposure. Prior to exposure, the substrates should be cooled down to room temperature. It is recommended to temper subsequently on the hot plate at 105°C – 110°C for about 2 min, to achieve cross-linking.

For a quick development of a few seconds (5 – 10 s), AR 300-12 or AR 600-70 is recommended. Developing for too long may cause an increase of dark erosion in the case of AR-N 4650-10. A suitable stopper is AR 600-60. The resist layers must be rinsed with DI-water and dried immediately after developing.

The sensitivity for a layer thickness of 10 µm is approximately 120 – 140 mJ/cm2 in broadband UV.

Fig. 1 and 2: Atlas 46S and Atlas 46R are very well suited for the generation of defined structures with vertical walls.

Atlas 46S can be structured at a wavelength of 365nm (i-line), but it is significantly more sensitive in the wavelength range of 250 – 320nm and nearly transparent at 405nm or respectively 436nm (h- or respectively g-line). By use of optimized PAG’s, the photosensitivity of the resist version SX AR-N 4610-10/1 can be significantly increased at 365nm:

Fig. 3: Overlap spectrum of a mercury vapor discharge lamp (blue line) and the absorption curve of SX AR-N 4610-10/1

The new special resist SX AR-N 4620-10/1 can even be structured in the wavelength range of 405 nm up to 436 nm.

The different absorption characteristics can be used to generate well-defined 3d structures:

Fig. 4: Process overview for the generation of three-dimensional architectures in the two-layer process with AR-N 4600-10 as bottom resist and SX AR-N 4610-10/1 or respectively SX AR-N 4620-10/1 as top resist

The process was applied successfully for the generation of bridged resist structures:

Fig. 5: 3d structures generated in two-layer process

Overview Photoresists- Positive



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]]> Black resist https://www.allresist.com/black-resist/ Wed, 01 Jun 2022 11:30:36 +0000 https://www.allresist.com/?p=17432 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.

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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.  The optically protected area should possibly cover the whole UV/VIS range from 200 – 1.000 nm. For the area of 200 -350 nm this is quite simple, since the resist components already absorb sufficiently there. For wave lengths > 350 nm, colorants must be added, which generate the desired absorption for longer waves.

We now have developed a resist which fulfills the requirements. First experiments resulted in a sufficiently high absorption up to 800 nm, the layer thus can be regarded as optically dense. We have mixed a negative resist with black and dark blue colorants and measured the absorption of the resulting layer thickness. Fig. 1 shows the absorption spectrums. At a thickness of 23 µm, the area of 300 – 800 nm is optically dense.

Fig. 1 UV/VIS spectrums of the black resist layers

Fig. 2 Visual image of the optical density (5 µm, 10 µm, 23 µm)

Even at a layer thickness of 23 µm, structuring is still possible. Common photolithography can be used here. This layer, however, needs a very strong aqueous-alkaline developer  (AR 300-26 or AR 300-73 1 : 1 diluted).

Fig. 3 AR logo structures in black resist

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]]> General: Resist composition https://www.allresist.com/general-resist-composition/ Wed, 01 Jun 2022 10:20:07 +0000 https://www.allresist.com/?p=17426 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.

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General: 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. Moreover, there are special resists such as the positive polyimide resists and negative polyimide resists (high temperature application > 400 °C, polymer polyimide), negative polyhydroxystyrene resists (high temperature application > 300 °C), negative PMMA photo resists (non-aqueous development for sensitive substrates, polymer PMMA and cross-linker), positive and negative two-layer photo resists (lift-off technology, polymer copolymer PMMA).

Overview Photoresists- Positive



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]]> Waterfree developable special resist SX AR-N 4810/1 https://www.allresist.com/waterfree-developable-special-resist-sx-ar-n-4810-1/ Thu, 19 May 2022 10:41:18 +0000 https://www.allresist.com/?p=17359 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.

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Waterfree 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. SX AR-N 4810/1 is offered as a solution in anisole and contains, besides PMMA, crosslinkers and aminic components. X AR 300-74/1 or MIBK are suitable developers.

With the resist system, thicker layers up to 3,5 µm can be realized as well. Our developer X AR 300-74/3 is particularly well suited for maximum coating thickness, the sensitivity is in the range of approximately 600 – 650 mJ/cm2 (broadband UV). The resulting structures are stable up to 230 °C and transparent in the optical wavelength range >300 nm.

Overview Photoresists- Negative



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]]> Top surface imaging (TSI) photoresist – principles https://www.allresist.com/top-surface-imaging-photoresist-principles/ Thu, 19 May 2022 10:02:40 +0000 https://www.allresist.com/?p=17350 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.

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Top surface imaging (TSI) photoresist – principles

Roland and Coopmans (Proc. SPIE 631, 34 (1986)) 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. In exposed areas, indene carboxylic acid is formed from naphthoquinone diazide (LSC; see Wiki Photosensitive components). At the same time, the inhibitory effect of the LSCs protecting the OH-groups of the novolac is reversed (see Wiki Photosensitive components. If now a gas-phase silylation of the surface is performed, organosilicon components (for example HMDS) penetrate the resist layer in irradiated areas and react with exposed OH groups of the novolac. In unexposed areas however, the protection due to the inhibitory effect is still maintained and HMDS is not able to diffuse into the layer. If then an oxygen plasma etching step is carried out, non-volatile silicon oxides (SiOx) are formed in exposed structures (silicon-containing), while volatile oxidation products are formed in non-silylated regions. The resist is consequently removed in these places (dry development of the resist). Since the exposed areas remain, the resist works as negative-tone resist.

It is already sufficient for this process if the organosilicon compound penetrates only 100-200 nm deep into the exposed areas. The resulting SiOx mask of this depth is enough to completely develop also significantly thicker photoresist layers. A high resolution can be achieved due to this thin structure imaging on the surface (top surface imaging). Likewise, a coating and at the same time planarization of topologically structured substrates is very well possible since the imaging process takes only place on the surface. A development with oxygen plasma can easily remove the different layer thicknesses (topologies). This system is furthermore suitable for highly reflective substrates (e.g. aluminium) since no complete exposure down to the bottom is required.

Plasma-developed structures on topologies

SiOx mask of SX AR-N 7100/2

Resist lines after O2-RIE development over aluminum structures with SX AR-N 7100

Allresist now developed a TSI photoresist. Negative resist SX AR-N 7100/2 is a safer solvent-based experimental sample suitable for g- and i-line lithography. After image-wise exposure and gas phase silylation, the resist mask is developed plasma-chemically (O2-plasma). The handling process comprises the following steps:

  • Spin coating
  • Tempering (100 °C bis 130 °C)
  • Exposure (436 nm, 365 nm)
  • Pre-tempering silylation (175 °C for HMDS respectively 110 – 130 °C for TMDS)
  • Gas phase silylation (165 °C for HMDS respectively 110 – 130 °C for tetramethyldisilazane)
  • Dry development (O2 plasma)

The duration of the silylation step depends on the specific technical conditions.

The gas phase silylation can be replaced by liquid silylation.

Overview Photoresists- Positive



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]]> Structuring by ablation of the resist materials https://www.allresist.com/resist-wiki-structuring-by-ablation-of-the-resist-materials/ Mon, 09 Jul 2018 12:18:50 +0000 https://www.allresist.de/?p=6893 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.

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Structuring 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. This process can be promoted by introducing suitable dye additives. The result is transparent structures (ablated surfaces) in the otherwise opaque surface.

Within the scope of the Photoenco project (June 2016 – May 2019), protective resist samples with dyes were created. Layers of these samples were irradiated with a 532 nm laser of different intensity. The figure demonstrates that with increasing laser power, the layer is completely ablated.

Figure: Lines written with 532-nm laser into PMMA and novolac layers

Resist samples for different laser wavelengths can be manufactured with appropriate dyes.

Overview Other Resists



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]]> Bleachable resists https://www.allresist.com/resist-wiki-bleachable-resists/ Mon, 09 Jul 2018 06:23:03 +0000 https://www.allresist.de/?p=6878 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.

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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.

During the fabrication of the first samples it however soon became apparent that the version of dyes changing their colour upon irradiation would not be favoured. Most dyes which were merely intended to change their colour turned out to be not stable enough for the required process conditions and temperatures. It was thus searched for dyes that are decomposed by energy input upon laser irradiation – the resist consequently bleaches in these areas.

Since a 532 nm laser should be used for the later process and since also the ablation experiments were carried out at this wavelength, we focused our attention on dyes with high absorption at this wavelength. In addition to red and violet dyes, classically also black dyes come into question. After first internal tests with a suitable dye, one sample (SX AR-N 4340/13.1) was submitted to the Institute of Technical Optics of the University of Stuttgart (ITO) for further investigation. The advantage of this resist system was the optical density of the resist. The ITO was able to successfully write lines into the resist without ablating it (Figure 1). Figure 2 and 3 show that unwanted ablation results if the intensity of the laser beam is too high.

Fig 1: Lines written at the ITO Stuttgart by bleaching the dye with laser irradiation.

Fig 2: Lines written at the ITO Stuttgart by bleaching the dye with laser irradiation of too high intensity – incipient ablation.

Fig. 3: Lines written at the ITO Stuttgart by bleaching the dye with laser irradiation of far too high intensity – significant ablation.

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]]> Fluorescent resist structures with photoresists https://www.allresist.com/resist-wiki-fluorescent-resist-structures-with-photoresists/ Wed, 25 Apr 2018 15:05:05 +0000 https://www.allresist.de/?p=6768 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.

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Fluorescent 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. The dyes are stable, and the structuring can be performed according to the same protocol as generally used for non-coloured Atlas 46 S.

The intense fluorescence withstands tempering at 150 °C; and even UV exposure required for cross-linking of Atlas resist films has no adverse effect on the emission properties of the resulting fluorescent layers.

Fig. 1-2: Different fluorescent Atlas 46 layers (irradiation with black light)

It is even possible to manufacture two-coloured fluorescent architectures with these resists. For this purpose, glass plates were firstly treated with AR 300-80 (new) and then coated with different fluorescent Atlas 46 S variants (1000 rpm, 90 s, SB 65 °C for 10 minutes). Subsequently, exposure was carried out (flood exposure, 4 minutes) using different masks (“AR logo small” as positive and as negative mask). After a PEB  for 3 minutes between 105 °C and 110 °C, development was performed in PMA (time for complete development was about 10 – 15 s, but layers are still stable after 30 – 60 s) and blown dry. The successfully realised and fully developed structures were subsequently coated with a second resist (750 rpm, 2 minutes, SB 10 min at 65 °C). The second colour was chosen according to the greatest possible colour contrast (e.g. the combination blue-yellow or red-yellow).  Both resists do not mix since already established structures are highly stable. The second exposure (as well as the PEB; analogous to the first step) allowed the structuring of the upper layer (for the AR logo, inverse masks were used). After development with PMA, the differently fluorescent areas on the substrate become visible in black light:

Fig. 3-6: AR logo with two-coloured emission in black light

Also differently fluorescing lines adjacent to other can be created in the same way:

Fig. 7-8: Different fluorescent patterns of lines and structures

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]]> Atlas 46 for nanoimprint lithography https://www.allresist.com/resist-wiki-atlas-46-for-nanoimprint-lithography/ Mon, 15 Jan 2018 07:18:05 +0000 https://www.allresist.de/?p=6684 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

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Atlas 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 Atlas 46S and cured with UV light at a wavelength of 172 nm. The subsequent imprint step then yielded the desired hierarchical architecture.

  1. Realization of defined nanostructures by thermal imprinting
  2. Stabilization of the pre-structured surface by deep UV exposure
  3. Second imprint step to generate the hierarchical architecture

For this special application, different resists were evaluated:

Fig .: Evaluation of different negative photoresists for double imprint lithography

SU 8 and Atlas-resists show similarly good results since defined and very uniform structures could be generated, while CAR44 does not have the thermal stability required for this process. The big advantage of Atlas-resists however is the easy removability of the R-variant.

Overview Other Resists



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