Supercritical CO_2 for High Resolution Photoresist Development

摘要

Today's conventional microelectronic fabrication processes are able to produce features in the 100nm range or lower. However, tighter regulation of toxic chemical release, as well as the increasing energy cost associated with treating rinse water, means that the semiconductor industry is primed for the adoption of alternative solvent processes. Supercritical CO_2 (scCO_2) is a promising candidate as a replacement solvent. It is inexpensive, environmentally benign, combines the best properties of both a gas and liquid and can be easily separated from solutes. We have recently shown scCO_2 to be a prime replacement solvent for photoresist development, and have formulated photoresists for both positive and negative tone development processes. We demonstrate the solubility of small non-polymeric, molecular glass compounds in supercritical CO_2. Molecular glasses form amorphous films on planar substrates and may show excellent solubility in scCO_2 without the incorporation of fluorine or silicon. Using a phenolic molecular glass, line-space features of 50 nm were developed in scCO_2.