Optimized glass photographic mask
Abstract
Abstract A PROCESS FOR MAKING A PHOTOGRAPHIC OPTICAL GLASS MASK THAT IS USED IN SILICON INTEGRAED CIRCUIT WAFER PROCESSING. AN OPTICAL GLASS MASK IS MADE BY MEANS OF A STEP AND REPEAT CAMERA. DISPLACEMENT ERROR WHICH IS CAUSED BY THE DIFFERENCE IN CEFFICIENTS OF EXPANSION BETWEEN THE MICROSET SCALE OF THE STEP AND REPEAT CAMERA AND THE PHOTOGRAPHIC OPTICAL MASK, IS MINIMIZED BY USING THE SAME MATERIAL FOR BOTH ELEMENTS. FURTHER DISPLACEMENT ERROR CAUSED BY THERMAL MISMATCH OF THE OPTICAL GLASS MASK AND THE SILICON WAFER IS MINIMIZED BY USING A BOROSILICATE GLASS MASK HAVING A LINEAR COEFFICIENT OF EXPANSION OF 3.5X10-6/DEGREES C., WHICH SUBSTANTIALLY MATCHES HE LINEAR COEFFICIENT OF EXPANSION OF THE SILICON WAFER MATERIAL.
Inventors
- 👤 R Pecoraro
- 👤 P Castrucci
- 👤 N Haddad
Bibliographic Details
Claims Analysis
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| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1976-04-23 | 1976-10-23 | 1977-04-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-04-23 | 1980-10-23 | 1981-04-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-04-23 | 1984-10-23 | 1985-04-24 | $7700.00 | Window Closed / Lapsed |