The study of optical performance for quartz dry etching quality in ArF lithography

Abstract

Dry etching has become critical to manufacture the resolution enhancement technique (RET) mask in the ArF lithography. Among RET masks, alternating phase shift mask (PSM) and chrome-less phase lithography (CPL) mask require the formation of 180 degrees phase differences by quartz dry etching. There are many error factors, which can influence CD uniformities on mask and wafers, in Quartz dry etch step such as sidewall angle, phase MTT and uniformity, micro-trench, and morphology. Furthermore, quartz depth is hard to control because there is no stopping layer for quartz etching. Additionally, Pattern profile of Chrome layer is very important, because chrome profile affect sidewall angle for quartz. We have simulated and investigated to identify the influences of many error factors on RET. Consequently, we investigated characteristics of quartz dry etching process performance and the influences on resolution, which can be improved by dry etch parameters.