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.
A large variety of applications include a wet-chemical etching step which very often involves highly alkaline etching baths.
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.
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.
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.
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.
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.
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
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.
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.