A positive chemically amplified resist for 193-nm lithography has been developed. The resist consists of a copolymer of tetrahydro-4-methyl-2-oxo- 2H-pyran-4-yl methacrylate and 2-methyl-2-adamantyl methacrylate and a photoacid generator. The acid-catalyzed deprotection of the protective groups leads to a large polarity change in the exposed region of the resist films and it allows for high-contrast patterning with high sensitivity. Using an ArF excimer laser exposure system, a 0.17-µ m lines and spaces pattern has been resolved.

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Bi-level resist systems consisting of a thin top silicon containing resist and a thick bottom layer are very promising with ArF-excimer laser lithography for obtaining high-aspect patterns on a high-step substrate. We studied the 193 nm light sensitivity and the crosslinking mechanism of various crosslinking-type functional groups by molecular orbital (MO) calculations. We found that negative siloxane resists with suitable functional groups like chloromethylphenyl exhibit very high sensitivity without using a chemically amplified system, due to the high oscillator strength with many allowed 7t-1t* transitions caused by 193 nm irradiation. No profile deformation by excessive absorption is observed in the resist systems, due to the high 02-RIB resistive thin imaging resist layer. A 0.14 µm line and space pattern can be delineated at a dose of 7 mJ/cm2 using three-dimensional polysilphenylenesiloxane (TSPS) / novolak bi-level resist systems.