Patent US3815978A successfully refreshed from Google Patents.
US3815978A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Durable see-through photoresist mask
Assignee: International Business Machines Corp
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Filing: 1972-06-20
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Granted: 1974-06-11
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Expires: 1992-06-20
Abstract
Abstract A durable ''''see-through'''' photoresist mask is obtained by forming a layer of ruby on a sapphire substrate, and forming a layer of Cr2O3 on the ruby. This combination of materials acts to effectively absorb light over the sensitive range of approximately 3,000 to 4,500 A, and yet allows transmission of sufficient light in the visible range to permit visual alignment and positioning of the mask. The mask is fabricated, in one mode, by depositing a layer of Cr2O3 + Cr on a layer of sapphire and heating in an inert atmosphere to diffuse Cr into the sapphire and create a layer of ruby intermediate a layer of sapphire and Cr2O3.
Inventors
- 👤 J Marinace
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 02:16
CPC Classifications
G; G03; G03F; G03F1/00; G03F1/54; G03F1/58
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
35 words
The mask as set forth in claim 1 wherein said layer of Al2O3 includes a layered region of Cr-doped Al2O3 having a pattern formed therethrough corresponding to the said pattern in said layer of Cr2O3.
Claim 2
Dependent Claim
16 words
The mask as set forth in claim 2 wherein said layer of Cr2O3 includes free Cr.
Claim 3
Dependent Claim
56 words
The mask as set forth in claim 3 wherein said layered region of Cr-doped Al2O3 is formed by diffusing at least some of said free Cr in the said layer of Cr2O3 into the Al2O3 therebeneath in said layer of Al2O3 so as to thereby form a ruby layer in contact with said layer of Cr2O3.
Claim 4
Dependent Claim
15 words
The mask as set forth in claim 4 wherein said layer of Al2O3 is sapphire.
Claim 5
Dependent Claim
18 words
The mask as set forth in claim 4 wherein said layer of Al2O3 is a sintered polycrystalline Al2O3.
Claim 6
Dependent Claim
16 words
The mask as set forth in claim 4 wherein said layer of Al2O3 is dense alumina.
Claim 7
Dependent Claim
15 words
The mask as set forth in claim 4 wherein said layer of Al2O3 is LUCALOX.
Claim 8
Dependent Claim
137 words
A semitransparent photoresist mask for blocking light within the range of sensitivity of the photoresist material employed therewtih and at the same time being sufficiently transparent to light within the visible range to allow the visual alignment thereof, comprising: a first layer of Al2O3 at least a portion of which is transparent to light within the visible range; a second layer of Cr-doped Al2O3 formed on said first layer and having a pattern formed therethrough to said first layer, and a third layer of Cr2O3 formed on said second layer and having the same pattern formed therethrough as said second layer so that said second and third layers cooperatively act to block light within the said range of sensitivity of the photoresist and at the same time transmit sufficient light to allow the said visual alignment thereof.
Claim 9
Dependent Claim
29 words
The mask as set forth in claim 9 wherein said layer of Cr-doped Al2O3 is formed by diffusing Cr from said layer of Cr2O3 into said layer of Al2O3.
Claim 10
Dependent Claim
31 words
The mask as set forth in claim 9 wherein said layer of Al2O3 is formed on a substrate of hard crystalline material which is transparent to light in the visible range.
Claim 11
Dependent Claim
31 words
The mask as set forth in claim 9 wherein said layer of Al2O3 is formed on a substrate of hard amorphous material which is transparent to light in the visible range.
Claim 12
Dependent Claim
15 words
The mask as set forth in claim 12 wherein said amorphous material is fused SiO2.
Claim 13
Dependent Claim
15 words
The mask as set forth in claim 9 wherein said layer of Al2O3 is sapphire.
Claim 14
Dependent Claim
17 words
The mask as set forth in claim 9 wherein said layer of Al2O3 is sintered polycrystalline Al2O3.
Claim 15
Dependent Claim
20 words
The mask as set forth in claim 9 wherein said range of sensitivity is approximately 3,000 A to 4,500 A.
References Cited (Backward Citations)
US3508982A
Cited
US3561963A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-06-10 | 1977-12-10 | 1978-06-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-06-10 | 1981-12-10 | 1982-06-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-06-10 | 1985-12-10 | 1986-06-11 | $7700.00 | Window Closed / Lapsed |