The resolution and critical dimension control requirements for photomask fabrication are increasing at a dramatic rate due to advances in wafer lithography systems and photoresist technology. For example, phase shifting techniques for 5x reduction steppers require subresolution phase shifter elements as small as 0.5 micrometers to be patterned on the reticle. Unity magnification systems such as 1x optical steppers and deep UV 1x steppers require sub- half micron resolution on the reticle. The latest generation of electron-beam mask making systems is capable of patterning these structures in the resist film. However, traditional wet etch is not capable of successfully transferring the pattern from the resist into the chrome. This paper discusses a dry etch chrome process that has been developed at TRW. Sub-half micron resolution is characterized and explained in terms of chrome etching parameters. Selectivity and process sensitivities are explored for a potential manufacturing process. Finally, a dry etch process is used to fabricate actual reticles for an Ultratech 1500 1x optical stepper for use in a wafer manufacturing line.

Date Published: 26 March 1993
PDF: 12 pages
Proc. SPIE 1809, 12th Annual BACUS Symposium on Photomask Technology and Management, (26 March 1993); doi: 10.1117/12.142153

Published in SPIE Proceedings Vol. 1809:
12th Annual BACUS Symposium on Photomask Technology and Management
Scott Landstrom; Richard LaFrance, Editor(s)