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.
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.
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 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.
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.
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.
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.
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.
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 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