An automatic angular positioning of mask with wafer using modified moire technique

Brahm Pal Singh; Dr. Kowsalya; Rina Sharma; Ram Narain; Alok K. Kanjilal; Ramesh P. Singh; Vijay Trimbak Chitnis; Yoshihisa Uchida

doi:10.1117/12.637260

16 December 1992 An automatic angular positioning of mask with wafer using modified moire technique

Brahm Pal Singh, Dr. Kowsalya, Rina Sharma, Ram Narain, Alok K. Kanjilal, Ramesh P. Singh, Vijay Trimbak Chitnis, Yoshihisa Uchida

Author Affiliations +

Proceedings Volume 1622, Emerging Optoelectronic Technologies; (1992) https://doi.org/10.1117/12.637260
Event: Emerging OE Technologies, Bangalore, India, 1991, Bangalore, India

Abstract

An automatic and accurate technique for angular positioning of mask with respect to wafer is reported.. Alignment marks are in the form of gratings and the moire signal is obtained by the relative displacement between the gratings. The higher slope region of the moire signal is used to obtain higher sensitivity and better position control accuracy. The experiments are performed with 25 micrometer pitch gratings and Piezo- Electric Transducer is used for the angular displacement. The angular -7 accuracy of the order of 2 x 10 radian is reported with a time constant of 0.2 sec. In the recent years, use of moire interference technique for mask to wafer alignment has attracted much attention especially in VLSI fabrication technology where a highly accurate linear and angular positioning is involved. In this technique the alignment marks are in the form of gratings. A laser beam is passed normally through a mask grating and reflected from the wafer grating. Intensity variation in the reflection mode due to relative angular rotation is detected by a photodetector and converted into the electrical signal, known as moire signal.

Citation Download Citation

Brahm Pal Singh, Dr. Kowsalya, Rina Sharma, Ram Narain, Alok K. Kanjilal, Ramesh P. Singh, Vijay Trimbak Chitnis, and Yoshihisa Uchida "An automatic angular positioning of mask with wafer using modified moire technique", Proc. SPIE 1622, Emerging Optoelectronic Technologies, (16 December 1992); https://doi.org/10.1117/12.637260

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available