Phase Errors in PSMs at the 90nm Node

摘要

Embedded attenuated phase-shift masks (EAPSMs), also referred to as half-tone masks, provide larger process windows over binary masks in a given photolithography system. Today, most wafer fabs use 193 nm EAPSM technology to pattern the most critical layers for 90 nm node logic and 110 nm node DRAM devices. When an EAPSM is used, the associated phase angle and absorber transmission will impact the effective wafer process window. Giang and Gang performed a preliminary study on the phase-angle effect of 248 nm EAPSM on process window during etch process development. Because the 90 nm node is a relatively new technology, it is important to understand the effects of phase angle and transmission of a 193 nm EAPSM on process latitude, and establish practical control specifications for phase angle and transmission of EAPSMs for device production.