Characteristics of Silicon-Based Negative Resists in ArF Excimer Laser Lithography

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 193nm 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 π-π* transitions caused by 193nm irradiation. No profile deformation by excessive absorption is observed in the resist systems, due to the high O2-RIE resistive thin imaging resist layer. A 0.14μm line and space pattern can be delineated at a dose of 7mJ/cm2 using three-dimensional polysilphenylenesiloxane (TSPS)/novolak bi-level resist systems.