Automatic angular alignment in mask aligner using computer controlled moire technique

Author

Furuhashi, H. ; Hayashi, N. ; Watanabe, S. ; Higa, S. ; Uchida, Y. ; Singh, B.P. ; Kashyap, K.

Author_Institution

Aichi Inst. of Technol., Toyota, Japan

Volume

2

fYear

1996

fDate

5-10 Aug 1996

Firstpage

1318

Abstract

A novel method for the automatic alignment of masks with respect to a wafer in a mask-aligner is developed and reported. Alignment marks are used in the form of gratings of 25 μm pitch. The effect of various parameters on moire fringes is studied theoretically and experimentally, and the results are found to be in good agreement. A computer controlled moire sensor is employed to obtain the angular alignment accuracy of the order of ±130 nanoradians. This high accuracy is maintained for more than 5 minutes. Feasibility experiments are performed for wafers of various sizes and very high accuracy is obtained in each case

Keywords

diffraction gratings; integrated circuit manufacture; manufacturing processes; masks; moire fringes; process control; spatial variables control; alignment accuracy; automatic angular alignment; computer controlled moire technique; feasibility experiments; gratings; mask aligner; Automatic control; Circuits; Diffraction gratings; Energy consumption; Optical reflection; Optical sensors; Photodetectors; Signal generators; Signal processing; Very large scale integration;

fLanguage

English

Publisher

ieee

Conference_Titel

Industrial Electronics, Control, and Instrumentation, 1996., Proceedings of the 1996 IEEE IECON 22nd International Conference on

Conference_Location

Taipei

Print_ISBN

0-7803-2775-6

Type

conf

DOI

10.1109/IECON.1996.566070

Filename

566070