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Patent US3790412A successfully refreshed from Google Patents.
US3790412A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of reducing the effects of particle impingement on shadow masks
Assignee: AT&T Inc
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Filing: 1972-04-07
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Granted: 1974-02-05
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Expires: 1992-04-07
Abstract
Abstract Thermal expansion of shadow masks used in ion implantation processes has been found to cause inaccuracies in the ion implanted pattern. Such inaccuracies are reduced or eliminated by first directing a heating current into the mask, monitoring the resistance of the mask, and controlling the heating current in accordance with monitored resistance. As the mask is bombarded with ions, any temperature rise increases the monitored resistance to automatically reduce the heating current, thus compensating for the thermal effect of ion bombardment.
Inventors
- 👤 R Moline
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 06:05
CPC Classifications
H; H10; H10P; H10P30/00; H10P30/20; F; F01; F01D; F01D5/00; F01D5/30; H10P30/22; H10P95/00; Y; Y10; Y10S; Y10S148/00; Y10S148/106; Y10S438/00; Y10S438/942; Y10S438/944
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
38 words
The improvement of claim 1 wherein: the second energy imparted to the mask is caused by electrical current; and the step of reducing the second energy imparted to the mask comprises the step of reducing said electrical current.
Claim 2
Dependent Claim
30 words
The improvement of claim 2 further comprising the step of: monitoring the electrical resistance of the mask; and controlling the electrical current as a function of said monitored electrical resistance.
Claim 3
Dependent Claim
43 words
The improvement of claim 3 wherein: said substrate is a semiconductor substrate; and the steps of projecting particles through the mask comprises the step of irradiating the mask with ions, some of which are transmitted through openings in the mask to the substrate.
Claim 4
Dependent Claim
61 words
The improvement of claim 4 wherein: the step of transmitting electrical current through the mask comprises the step of transmitting current to a plurality of locations on one side of the mask by a plurality of conductors; and further comprising the step of equalizing the electrical current distribution in the mask by adjusting the relative resistance of said plurality of conductors.
Claim 5
Dependent Claim
67 words
In a method for forming a pattern on a substrate comprising the steps of projecting particles through a mask onto the substrate, the improvement comprising the steps of: directing a heating current through the mask; monitoring the electrical resistance of the mask; and controlling the heating current as a function of said electrical resistance, thereby to compensate for the heating effects of particles impinging on said mask.
Claim 6
Dependent Claim
43 words
The improvement of claim 6 wherein: the step of projecting particles through the mask comprises the step of raster scanning the mask with a beam of ions, thereby to implant in the substrate ions that are projected through the apertures in the mask.
References Cited (Backward Citations)
US2695852A
Cited
US2949815A
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US2933979A
Cited
US3113896A
Cited
US3501342A
Cited
US3713922A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-02-04 | 1977-08-06 | 1978-02-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-02-04 | 1981-08-06 | 1982-02-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-02-04 | 1985-08-06 | 1986-02-05 | $7700.00 | Window Closed / Lapsed |