Photoresist Dissolution into a CO_2 Compatible Salt and CO_2 Solution: Investigation of Processing Conditions

摘要

New lithographic techniques are being implemented to help further reduce feature sizes in microelectronics. A technique for the development of standard extreme ultraviolet (EUV) photoresists in a carbon dioxide compatible salt (CCS) and supercritical carbon dioxide (scCO_2) solution is being investigated to reduce line edge roughness and image collapse of high aspect ratio features. To understand the kinetics and overall mechanism of photoresist dissolution into the high pressure CCS/scCO_2 solution, a quartz crystal microbalance (QCM) was previously used to measure the effects of temperature, pressure, and density on the photoresist removal rate. In this paper, the effects of a CO_2 drying step before development and an adhesive coating on the photoresist removal rate and the formation of residual photoresist droplets were studied at 50 ℃ and 5000 psi. The results implied that neither the CO_2 drying step nor the HMDS coating had an effect on the bulk photoresist removal rate. It was also found that using an HMDS adhesive coating reduces residual photoresist droplet size on the substrate due to the lower substrate / photoresist surface energy.