Depolymerization chemical amplification resists based

A shown in Fig. 7.1, there are two hroad categories of chemical amplification resists based on their imaging mechanisms, namely, (i) those based on acid-catalyzed main chain scission and (ii) those based on functional group polarity switch brought about by acid-catalyzed deprotection of lipophilic pendant groups, depolymerization, and Claisen rearrangement. 

Faced with the shortcomings of the polyphthaldehyde resist (presented helow in chemical amplification resists based on depolymerization), the search for chemically amplified DUV resists resulted in a quick switch to more stable materials based on poly(p-hydroxystyrene), a phenolic polymer that Willson et al. were studying as a potential replacement for novolac. They observed that poly(p-tert-butoxycarbonyloxystyrene) (PBOCST), which is poly(vinyl phenol) protected with tert-butoxycarbonyl groups (t-BOC), is far more stable than the unprotected p-hydroxystyrene and could be purified and polymerized under controlled conditions. The resulting protected polymer could be easily deprotected thermally by heating it to 200°C or to a much lower temperature (100°C) by treatment with acid generated from the exposure of onium salts, just as in the poly(phthaldehyde)... 

Three component, aqueous-base developable, positive-tone resists utilizing the chemical amplification principle have also recently been reported (81,82). In these systems, irradiation of a phenolic resin/inhibitor/acid generator resist generates an acid which upon mild heating, catalyzes either depolymerization or deblocking of a... 

S Chemical amplification positive resists based on depolymerization 7.2.2.5.1 Poly(phthaldehyde) resist... 

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