US4391034A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Thermally compensated shadow mask
Assignee: International Business Machines Corp
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Filing: 1980-12-22
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Granted: 1983-07-05
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Expires: 2000-12-22
Abstract
Abstract In vacuum sputter cleaning and plating operations forming a patterned metallic layer on a silicon semiconductor chip, alignment is maintained by anticipating the difference in thermal expansion between the molybdenum mask and the silicon chip and forming the apertures in the molybdenum mask in a radially offset position with respect to the intended cleaning and deposition locations on the semiconductor chip, when the mask and the chip are at room temperature. Then, when the mask and the silicon chip are maintained in a concentric position and are raised to the cleaning and deposition temperature, the differential expansion of the molybdenum mask will bring the apertures therein into perfect alignment with the intended deposition locations on the silicon wafer.
Inventors
- 👤 Kenneth P. Stuby
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 16:15
CPC Classifications
G; G03; G03F; G03F7/00; G03F7/70; G03F7/70425; G03F7/70433; C; C23; C23C; C23C14/00; C23C14/04; C23C14/042; G03F9/00; H; H10; H10P; H10P72/00; H10P72/50; H10P72/57; Y; Y10; Y10S; Y10S438/00; Y10S438/942; Y10S438/945
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
155 words
An improved high temperature shadow mask for a large diameter silicon wafer, comprising: a planar plate having a pattern of apertures misregistered at room temperature but registered at high temperature during a deposition process each of whose respective distances from the centroid of said plate at room temperature is misregistered with respect to the corresponding desired distance from the centroid of said wafer of a corresponding shadow image on the silicon wafer at room temperature, by approximately the product of the difference between said high temperature and said room temperature times said desired distance times the difference between the thermal coefficient of expansion of the plate material and the thermal coefficient of expansion of the silicon wafer; whereby when the plate and silicon wafer are raised to said high temperature for processing, the differential expansion of the plate material will bring the apertures therein into alignment with the intended deposition locations on the silicon wafer.
Claim 2
Dependent Claim
155 words
An improved high temperature shadow mask for a large diameter silicon wafer, comprising: a planar plate having a pattern of apertures misregistered at room temperature but registered at high temperature during a deposition process each of whose respective distances from the centroid of said plate at room temperature is misregistered with respect to the corresponding desired distance from the centroid of said wafer of a corresponding shadow image on the silicon wafer at room temperature, by approximately the product of the difference between said high temperature and said room temperature times said desired distance times the difference between the thermal coefficient of expansion of the plate material and the thermal coefficient of expansion of the silicon wafer; whereby when the plate and silicon wafer are raised to said high temperature for processing, the differential expansion of the plate material will bring the apertures therein into alignment with the intended deposition locations on the silicon wafer.
Claim 3
Dependent Claim
181 words
An improved high temperature shadow mask for a large diameter silicon wafer, comprising: a planar plate having a pattern of apertures misregistered at room temperature but registered at high temperature during a deposition process, each of whose respective distances from the centroid of said plate at room temperature is misregistered with respect to the corresponding desired distance from the centroid of said wafer of a corresponding shadow image on the silicon wafer at room temperature, by approximately the product of the difference between said high temperature and said room temperature times said desired distance times the difference between the thermal coefficient of expansion of the plate material and the thermal coefficient of expansion of the silicon wafer; whereby when the plate and silicon wafer are clamped in a fixture which does not maintain said plate centroid and said wafer centroid mutually coincident at said high temperature and are raised to said high temperature for processing, the differential expansion of the plate material will bring the apertures therein into a minimum total misalignment with the intended deposition locations on the silicon wafer.
Claim 4
Dependent Claim
181 words
An improved high temperature shadow mask for a large diameter silicon wafer, comprising: a planar plate having a pattern of apertures misregistered at room temperature but registered at high temperature during a deposition process, each of whose respective distances from the centroid of said plate at room temperature is misregistered with respect to the corresponding desired distance from the centroid of said wafer of a corresponding shadow image on the silicon wafer at room temperature, by approximately the product of the difference between said high temperature and said room temperature times said desired distance times the difference between the thermal coefficient of expansion of the plate material and the thermal coefficient of expansion of the silicon wafer; whereby when the plate and silicon wafer are clamped in a fixture which does not maintain said plate centroid and said wafer centroid mutually coincident at said high temperature and are raised to said high temperature for processing, the differential expansion of the plate material will bring the apertures therein into a minimum total misalignment with the intended deposition locations on the silicon wafer.
Claim 5
Independent Claim
196 words
A method for making an improved high temperature shadow mask assembly for a large diameter silicon wafer, comprising the steps of: forming a planar plate having a pattern of apertures misregistered at room temperature but registered at high temperature during a deposition process, each of those respective distances from the centroid of said plate at room temperature is misregistered with respect to the corresponding desired distance from the centroid of said wafer of a corresponding shadow image on the silicon wafer at room temperature, by approximately the product of the difference between said high temperature and said room temperature times said desired distance times the difference between the thermal coefficient of expansion of the plate material and the thermal coefficient of expansion of the silicon wafer; clamping said plate and said wafer with their said centroids mutually coincident, in a fixture which does not maintain their said centroids mutually coincident at said high temperature; raising the temperature of said plate and silicon wafer to said high temperature for processing; whereby the differential expansion of the plate material will bring the apertures therein into a minimum total misalignment with the intended deposition locations on the silicon wafer.
Claim 6
Independent Claim
196 words
A method for making an improved high temperature shadow mask assembly for a large diameter silicon wafer, comprising the steps of: forming a planar plate having a pattern of apertures misregistered at room temperature but registered at high temperature during a deposition process, each of those respective distances from the centroid of said plate at room temperature is misregistered with respect to the corresponding desired distance from the centroid of said wafer of a corresponding shadow image on the silicon wafer at room temperature, by approximately the product of the difference between said high temperature and said room temperature times said desired distance times the difference between the thermal coefficient of expansion of the plate material and the thermal coefficient of expansion of the silicon wafer; clamping said plate and said wafer with their said centroids mutually coincident, in a fixture which does not maintain their said centroids mutually coincident at said high temperature; raising the temperature of said plate and silicon wafer to said high temperature for processing; whereby the differential expansion of the plate material will bring the apertures therein into a minimum total misalignment with the intended deposition locations on the silicon wafer.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-07-04 | 1987-01-03 | 1987-07-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-07-04 | 1991-01-03 | 1991-07-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-07-04 | 1995-01-03 | 1995-07-05 | $7700.00 | Window Closed / Lapsed |