Optimization of the composition of a new MRS-type negative resist

Sensitizer concentration is optimized for a new negative photoresist, MRL (Micro Resist for Longer wavelengths) with the assistance of computer simulation. The resist, which has photosensitivity in the ordinary UV region, resembles a deep UV resist MRS in terms of light absorption characteristic. It is found that a photosensitizer concentration of 20 wt% (based on the resin) is suitable for a reduction projection exposure system that utilizes UV light at 365 nm. A steep profile resist image of 0.7-µm lines and 0.7-µm spaces in a 1.0-µm thick resist layer is obtained using the MRL of optimized composition and the exposure system.