Radiation-induced negative resists

1 Negative resists based on radiation-induced cross-linidng reactions 

Generally, the reactions that generate cross-links in polymeric systems are classified into two types, namely, those where cross-links are formed by the direct reaction of an excited molecule or group, and those where cross-links are formed through the action of a radiation-generated reactive species in the ground state. The following describes both types. 

Reiser, Photoactive Polymers The Science and Technology of Resists, p. 24, John Wiley Sons, Hoboken, NJ (1989). 

The role of bitumen of Judea in the invention of photohthography and photography is described in Chapter 2, for it was the resist that was used to the capture the first permanent image from nature. 

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The scheme of radiation-induced reactions of CMS, negative electron resist, is proposed as follows on the basis of the present pulse radiolysis data. 

Many reports have been published on negative electron-beam resists. Most of these resists utilize radiation-induced gel-formation as the insolubilzation reaction. However, a major problem with these resists, is that their resolution is limited by swelling which is induced by the developer during development. 

Resists function by radiation-induced alteration of the solubility of the materials. There are two basic classes of resist materials, namely, negative and positive resists (see Fig. 4.5). Negative resists become less soluble on exposure to radiation i.e., the unexposed areas can be selectively removed by treatment with an appropriate developer solvent. Positive resists selectively undergo an increase in solubility on exposure, enabling the exposed regions to be selectively removed in the developer. Both types of resists are formulated from polymers designed to have physical and chemical properties consistent with semiconductor... 

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). ... 

Liquid development, which is commonly applied in lithographic processes, depends on a radiation-induced alteration of the solubility of resist areas (see Figure 1.7). Provided that the resist consists of a linear polymer, the solubility is either lowered by intermolecular crosslinking (negative tone) or is augmented by... 

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