Application of dry etching process on high-end Cr photomasks

Abstract

As the design pattern size at photomask is rapidly down to sub-micron, photomask manufacturing face up the situation developed unfavorably who has been enjoyed the long vacation with the 5X reticle through the prematured wet process. Also the wet etching process, the traditional process of photomasks is faced the limitation of resolution, linearity and corner rounding. The isotropic etching through the chemical reaction under the photoresist on wet etching process suggest the resolution limitation of typical wet etching process around 1.0 micrometers +/- 0.2 micrometers . The poor corner rounding and linearity is also considered as the major spot o f wet etching process. As explained, the resolution limitation of wet process has been hindered the application in present semiconductors market and, in addition, far from the demand of 0.18 micrometers design rule. On this paper, we reviewed the comparison of dry and wet etching process result to clarify the possible improvements through the dry etching. And based on this comparison we set possible way of improvements at the conclusion.