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Proceedings Paper

Diffraction Gratings As Keys For Automatic Alignment In Proximity And Projection Printing
Author(s): Hans P. Kleinknecht
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Paper Abstract

Alignment keys in the form of diffraction gratings are described which can be used for automatic alignment in photolithography for the fabrication of integrated circuits. This technique is suitable for proximity printirg and for projection printing, 1:1 projection as well as reduction projection with step-and-repeat on the wafer. The system uses a small He-Ne laser, a chopper, a beam collimator and a number of silicon photodiodes. The signals from these photodiodes give a quantitative measure of the degree and direction of misalignment between mask and wafer. With suitable electronics these signals can be used for the control of servo motors in order to obtain automatic alignment. Our experiments with a 10:1 reduction projection set-up show that an alignment accuracy of 0.1 µm and alignment times of less than 1 sec are feasible. The alignment range is as large as ± 450 /µm.

Paper Details

Date Published: 17 July 1979
PDF: 7 pages
Proc. SPIE 0174, Developments in Semiconductor Microlithography IV, (17 July 1979); doi: 10.1117/12.957179
Show Author Affiliations
Hans P. Kleinknecht, Laboratories RCA Ltd (Switzerland)


Published in SPIE Proceedings Vol. 0174:
Developments in Semiconductor Microlithography IV
James W. Dey, Editor(s)

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