Chemically amplified negative resists

The bilayer silylation technique was later applied to a chemically amplified negative resist, focusing on the effects of a delay between the processes [462]. 

S.2 Chemically amplified negative resists based on radiation-induced polarity changes... 

H. Iwasaki, T. Itani, M. Fujimoto, and K. Kasama, Acid size effects of chemically amplified negative resist on lithographic performance, Proc. SPIE 2195, 164 172 (1994) U. Schedeli, N. Miinzel, H. Holzwarth, S.G. Slater, and O. Nalamasu, Relationship between physical properties and lithographic behavior in a high resolution positive tone deep UV resist, Proc. SPIE 2195, 98 110 (1994). 

Condensation polymerization mechanisms are probably the most prevalent in the design of chemically amplified negative resists and are the basis for the... 

Chemically amplified negative phenolic resists based on acid-catalyzed condensation/intermolecular dehydration cross-linking reactions... 

Takahashi, A. Shirakawa, H. Adegawa, Y. Chemically-amplified negative-working resist compositions for processing with electron beam or x-ray. Jpn. Kokai Tokkyo Koho JP 2003005355, 2003. 

Acid-C t lyzed Chemistry. Acid-catalyzed reactions form the basis for essentially all chemically amplified resist systems for microlithography appHcations (61). These reactions can be generally classified as either cross-linking (photopolymerization) or deprotection reactions. The latter are used to unmask acidic functionality such as phenohc or pendent carboxyhc acid groups, and thus lend themselves to positive tone resist apphcations. Acid-catalyzed polymer cross-linking and photopolymerization reactions, on the other hand, find appHcation in negative tone resist systems. Representative examples of each type of chemistry are Hsted below. 

In recent progress, calixarene resists have been prominent [105]. Hexaacetate p-methylcalix[6]arene was demonstrated to work as a high-resolution negative resist. This resist also shows high etch resistance. Calixarene resist has an advantage in its molecular size (about 1 nm). Liquid crystal resists and inorganic resists show high resolution [106]. These resists are suitable for the fabrication of nanostructures. However, the resist sensitivities are lower than those of chemically amplified resists, even PMMA. 

Typical resists include cyclized polyisoprene with a photosensitive crosslinking agent (ex bisazide) used in many negative photoresists, novolac resins with diazoquinone sensitizers and imidazole catalysts for positive photoresists, poly(oxystyrenes) with photosensitizers for UV resists, polysilanes for UV and X-ray resists, and polymethacrylates and methacrylate-styrenes for electron-beam resists (Clegg and Collyer, 1991). Also note the more recent use of novolac/diazonaphthoquinone photoresists for mid-UV resists for DRAM memory chips and chemically amplified photoacid-catalysed hydroxystyrene and acrylic resists for deep-UV lithography (Choudhury, 1997). 

Chemically amplified cross-linking negative resists... 

Another important example of a resist based on radiation-induced polarity change employs the photochemical transformation of N-iminopyridinium ylides (XXII) to 1,2-diazepines (XXIII) as the basis of a negative non-chemically amplified resist (Scheme 6.14). ... 

Chemically amplified condensation/intermolecular dehydration negative resists based on acid-catalyzed cross-linking with acid-sensitive electrophile (cross-linking agent)... 

S Chemically amplified methacrylate negative resists based on acid-catalyzed deprotection and development in supercritical CO2... 

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