Consumer demand for faster computers, increased data storage space, and higher density memory arrays has driven development efforts in photomask production the way of the wafer fab. This drive has pushed mask fabrication toward smaller and more uniform features. It has thus inspired the creation of a deep ultraviolet, or DUV, (257 nm) optical pattern generator and an attendant resist process for mask fabrication. A DUV photoresist process based on precoated photomask blanks is presented herein with a demonstrably robust resist, both in terms of plate shelf life and latent image stability. Benchmark lithographic performance in resolution, depth of focus (DOF), linearity, and iso/dense bias are presented. In addition, the ambient atmospheric stability of the resist system is explored. Traditional maskmaking has, until now, excluded a post-exposure bake (PEB) step. Equipment requirements and resist critical dimension (CD) performance as a function of PEB are also presented. Photoresist process parameter space is defined and discussed herein. Precoated mask blank post-apply bake (PAB) stability is also examined as it relates to after-develop inspection (ADI) CDs. Dark erosion tests are employed to study photoresist contrast uniformity as it relates to ADI CDs. First-pass specifications for incoming raw materials are also proposed.

Date Published: 22 January 2001
PDF: 12 pages
Proc. SPIE 4186, 20th Annual BACUS Symposium on Photomask Technology, (22 January 2001); doi: 10.1117/12.410734

Published in SPIE Proceedings Vol. 4186:
20th Annual BACUS Symposium on Photomask Technology
Brian J. Grenon; Giang T. Dao, Editor(s)