METAL-FREE CHEMICALLY AMPLIFIED POSITIVE RESIST RESOLVING 0.2-MU-M IN X-RAY-LITHOGRAPHY

A chemically amplified positive resist (EXP) and its processing have been optimized for high resolution in x-ray lithography. EXP is composed of a novolak resin, 2,2-bis(t-butoxycarbonyloxyphenyl)-propane as a dissolution inhibitor, and bis(p-t-butylphenyl)iodonium trifluoromethanesulfonate as an acid generator. Sensitivity and resolution characteristics were greatly influenced by post-exposure baking (PEB) conditions. Applying PEB at 65-degrees-C for 60 s resulted in the successful fabrication of 0.2-mu-m patterns in a 1.3-mu-m-thick EXP film. The pattern width remained virtually unchanged during a three-hour holding time between x-ray exposure and PEB. The exposure latitude for +/- 10% width change for 0.2-mu-m holes was about 10%.