Simulation of X-ray mask pattern displacement

• Published in: Japanese Journal of Applied Physics 1996-12, Vol.35 (12B), p.6469-6474
• Main Authors: ODA, M, UCHIYAMA, S, MATSUDA, T
• Format: Article
• Language: English
• Subjects: Applied sciences; Electronics; Exact sciences and technology; Microelectronic fabrication (materials and surfaces technology); Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices
• ISSN: 0021-4922; 1347-4065
• DOI: 10.1143/JJAP.35.6469

We have developed programs to calculate pattern displacement caused by membrane stress, absorber stress distribution and pattern density in X-ray masks. This paper describes the models upon which the calculations were based and shows how the results fit experimental ones. The membrane area shrinkage caused by SiN stress is calculated using a previously reported method. The pattern displacement caused by absorber stress is calculated using the stress gradients estimated for each point from the stress distribution measured in masks used in practice. It is found that the displacement in the membrane with non-patterned absorber is strongly affected by the absorber stress distribution. The influence of pattern density on pattern displacement is calculated using a model in which the absorber thickness is reduced in accordance with the volume etched off during patterning. Comparisons between calculated and experimental results of the pattern displacement in masks with simple patterns reveal that the calculated results agree with the experimental results with an accuracy of about 30 nm.