Performance of a chemically amplified positive resist for next-generation photomask fabrication

Abstract

A positive-tone, chemically amplified resist (CAR) has been evaluated in comparison with non-CARs in its applicability to fabrication of reticles to be used for 180-nm-rule devices. The evaluated CAR is found to have better performance than the non-CARs. It has high sensitivity and high contrast enough to be used with e-beam writing systems, and good dry-etch durability. Its characteristics when exposed with e-beam writing system with different acceleration voltages is studied. The CD linearity is maintain down to 400 nm for all patterns by adoption of a 50 kV e-beam system and a proximity effect correction. The resolution limit is 150 nm for lines-and-space pattern. The allowance of the baking conditions is examined and the use of a highly temperature-controllable hot-plate yields good CD uniformity. The influence of the ammonia concentration in the process environment of the post exposure delay stability is investigated. The CAR should be used under a concentration of ammonia less than ca. 5 ppb, which is obtainable by use of a chemical filter. In conclusion, it is demonstrated that the CAR meets our requirements for resist for 180-nm-rule reticle fabrication.