Advances in photo mask etch technology are clearing the way for 65nm alternating phase shifting masks (alt-PSM) to be used as a principal component in a typical mask set. As wafer features shrink to ever smaller sizes, the specifications on the photo mask etch performance become more and more stringent. To meet the challenging demands of 65nm technology, alt-PSM’s are employed to help deliver a reliable and repeatable pattern transfer to the wafer. Hence, especially in the framework of quartz dry etch technology for the production of high-end alt-PSM’s ever tightening specifications generate various efforts of machine vendors and mask making industry to meet the demands 1. This paper covers data from a ten experiment two level three factorial Design of Experiment. Therein, the effects of changing quartz process conditions (i.e., ICP power, RIE power, and gas chemistry) on the Applied Materials TetraTM II Photomask Etch System were investigated. As for alt-PSM's the universally agreed upon number one priority is phase angle uniformity followed closely by RIE lag, sidewall angle (SWA), and micro-trenching this was also taken into account during the optimization process of the DoE findings. The results show phase angle uniformity of less than 2.0° relative to a 180° etch depth and acceptable performance for RIE lag, SWA, and micro-trenching. Trends and graphs of the DoE are presented and discussed in detail.