RAPID THERMAL ANNEALING FOR REDUCING STRESS IN TUNGSTEN X-RAY MASK ABSORBER

TitleRAPID THERMAL ANNEALING FOR REDUCING STRESS IN TUNGSTEN X-RAY MASK ABSORBER
Publication TypeJournal Article
Year of Publication1993
AuthorsDiawara, Y., Lafontaine H., Chaker M., Kieffer J. C., Pepin H., Cochrane R. W., Currie J. F., Haghirigosnet A. M., Ravet M. F., and Rousseaux F.
JournalJournal of Vacuum Science & Technology B
Volume11
Pagination296-300
Abstract

X-ray masks are one of the key issues of x-ray lithography. In order to eliminate distortions, a good mask necessitates a low stress x-ray absorber layer. Tungsten is one of the most promising materials for use as an x-ray absorber, but the stress strongly depends on deposition conditions. Therefore, it is very difficult to control precisely the stress during the deposition process. A new approach is proposed, which consists of ''fine tuning'' the stress in the deposited layer with an annealing treatment. In this article, a process is presented which controls the stress in tungsten deposited thin films using rapid annealing. Stresses of less than 2 X 10(8) dyn/cm2 can be routinely obtained in annealed films for which initial compressive stresses after deposition were up to 3 X 10(9) dyn/cm2. This allows better film deposition process latitude for the sputtering gas pressure and substrate temperature. The evolution of stress with annealing temperature and time is studied and x-ray diffraction and scanning electron microscopy measurements are discussed.