Abstract

A dissolution rate model for Hoechst AZ PN114 for extreme ultraviolet (EUV) exposure is described and experimental results of effects of processing conditions on 0.1 μm imaging are presented. The dissolution model is based on volumetric energy deposited in the resist in J/cm³ and uses a standard molecular weight increase. It is derived from published electron-beam [2] and EUV [3] data along with new experiments at EUV wavelengths and was implemented in the SAMPLE lithography program by adding a new development rate Comparisons made between SEM cross-sections and simulations using proto-typical aberrations show similar undercutting shapes characteristic at these wavelengths but did not fully describe the top corner rounding. An extensive matrix of experiments of post exposure bake (PEB) time ranging from 2 1/2 minutes to 15 minutes and PEB temperature from 95°C to 115°C and exposure dose from 1.5 mJ/cm² to 10 mJ/cm² was carried out at Brookhaven National Laboratory in conjunction with AT & T Bell Laboratories to explore sensitivity tradeoffs and possible diffusion effects. Nominal conditions for 0.1 μm imaging were exposure at 3 mJ/cm² and post exposure bake for 5 minutes at 105°C. In general, an increase of 5°C requires a dose decrease of 1.5 mJ/cm² and every 5 minute increase in bake time leads to a decrease of 1.2 mJ/cm² to obtain similar sized features. It was observed that the AZ PN114 resist shows little diffusion except at high PEB temperatures of about 115°C. Debris or image imperfections seemed to be more noticeable at long PEB times.

© 1994 Optical Society of America