Materials for single-etch double patterning process: Surface Curing Agent and Thermal Cure Resist

摘要

Two different pattern curing techniques were developed to stabilize first lithographic images for the single-etch double patterning process. The first method uses a surface curing agent (SCA) that is coated on top of the patterned surface to form a protective coating layer during the curing bake process. It was found that the surface curing process with SCA offers minimum CD changes before and after the double patterning process. Virtually no CD change was observed with the first lithographic images at various curing bake temperatures ranging from 120 ～160℃ indicating the curing reaction is limited on the patterned surface. The second method uses a thermal cure resist (TCR) that is a special 193nm photoresist with a crosslinkable functional group to form an insoluble network upon heating at higher temperature. A single-step curing process of the first lithographic images was achieved using TCR by baking the patterned images at 180℃ for 60sec. A cross-line contact hole double patterning method was used to evaluate these two different curing techniques and both SCA and TCR successfully demonstrated their capability to print 45nm contact holes with excellent CD uniformity in immersion lithography (1.35NA) with a 45nm half pitch mask. It was also confirmed that both SCA and TCR can be extended to the top-coat free immersion double patterning process using an embedded barrier layer technique.