The Feasibility Study Of Thin Cr Film For Low Process Bias

As minimum feature size of device shrink down below 100 nm, the process margin for the mask fabrication reduced dramatically. Mask makers are enlisting equipment and material suppliers in their efforts to achieve wide process margin from existing processes. One of the most promising methods is thinning Cr thickness as low as possible. However, bringing the thin Cr blank into mass production line could cause some problem for advance photomask fabrication using 50 W electron beam writing tools. In this paper, we verified the feasibility of Cr film ranged from 400 Angstrom to 1000 Angstrom. The results categorized into two sections. At first, we verified the writing property change with thinning Cr thickness and then investigated the etching characteristics. As a result, we found that Cr thickness don't affect writing properties regardless of Cr thickness. However, the thinner Cr blank represented superior etching characteristics to a conventional one. It showed low etching bias and loading effects. From these results, we concluded the thinner Cr blank could not only make the process wider but also improve the mask quality.