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Proceedings Paper

Overlay Results Comparison Between Two Approaches When Mixing Optical Steppers With Scanner
Author(s): J. M. Dumant; G. Vachet; A. Charles; J. M. Temerson
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Paper Abstract

For the industrial production of one micron CMOS design rule circuits, it may be advantageous in terms of cost and throughput to mix projection scanners with optical steppers. Three compatibilities have then to be completed: - prealignment, interfield, intrafield. One classical way of ensuring the prealignment compatibility is to print two global marks with the stepper. To achieve the grid compatibility, the normal method is to use die by die alignment. The intrafield capability is then achieved in adjusting the magnification and distortion of the stepper to the scanner caracteristics. Nevertheless, a specific difficulty occurs when it is wished to print the first level with the stepper. In that case, two different aproaches can be considered: - First print an extra level with the scanning projection machine to create alignment marks, and afterwards print the real first level with the stepper in die by die alignment mode. - Use blind stepping under the stage interferometric metrology control to print directly the first level. Both method have been tested and characterized. Advantages and difficulties as well as overlay results are presented. A detailled analysis and quantitative evaluation of the various error causes involved were carried out. This allows the analysis to be generalized to other machines with different specifications

Paper Details

Date Published: 11 October 1989
PDF: 9 pages
Proc. SPIE 1138, Optical Microlithography and Metrology for Microcircuit Fabrication, (11 October 1989); doi: 10.1117/12.961747
Show Author Affiliations
J. M. Dumant, C.N.E.T. (France)
G. Vachet, C.N.E.T. (France)
A. Charles, C.N.E.T. (France)
J. M. Temerson, C.N.E.T. (France)

Published in SPIE Proceedings Vol. 1138:
Optical Microlithography and Metrology for Microcircuit Fabrication

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