US4360273A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Optical alignment of masks for X-ray lithography
Assignee: Unisys Corp
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Filing: 1980-02-14
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Granted: 1982-11-23
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Expires: 2000-02-14
Abstract
Abstract Optical alignment of the relative positions of cooperating masks and substrates is achieved for use in the generation by x-radiation of complex and compact patterns. Small fiduciary marks are actually illuminated by coherent visible light and the resultant diffraction patterns are used for alignment purposes. Fresnel half-period zone plates are used to produce interference patterns in the form of an operator-observable information bearing pattern on a viewable screen.
Inventors
- 👤 James B. Thaxter
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 10:45
CPC Classifications
G; G03; G03F; G03F9/00; G03F9/70; G03F9/7073; G03F9/7076
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
87 words
Apparatus for aligning a first planar optically transparent element with respect to a second planar optically transparent element disposed in substantially parallel relation comprising: first and second thin films affixed to major adjacent surfaces of said first and second planar elements respectively, said films being provided with first and second apertures respectively, each of said apertures containing a Fresnel zone plate, means for illuminating said Fresnel zone plate with collimated light, and means for viewing an interference pattern formed by light passing through said Fresnel zone plates.
Claim 2
Dependent Claim
87 words
Apparatus for aligning a first planar optically transparent element with respect to a second planar optically transparent element disposed in substantially parallel relation comprising: first and second thin films affixed to major adjacent surfaces of said first and second planar elements respectively, said films being provided with first and second apertures respectively, each of said apertures containing a Fresnel zone plate, means for illuminating said Fresnel zone plate with collimated light, and means for viewing an interference pattern formed by light passing through said Fresnel zone plates.
Claim 3
Dependent Claim
46 words
Apparatus as described in claim 1 wherein light transmittance of said second thin film is selected such that light passing through said second thin film, and light passing through said Fresnel zone plate contained in said second aperture have substantially equal intensities at said viewing means.
Claim 4
Dependent Claim
45 words
Apparatus as described in claim 2 where light transmittance T S of said second thin film is substantially: T.sub.S =d.sup.4 /(SCλ).sup.2 where: d=diameters of said apertures, s=effective distance between said first and second thin films, and c=a constant empirically dependent upon geometry of said apertures.
Claim 5
Dependent Claim
10 words
Apparatus as described in claim 3 where T S =0.1.
Claim 6
Dependent Claim
20 words
Apparatus as described in claim 2 additionally including means for parallel relative translation between said first and second planar elements.
Claim 7
Dependent Claim
31 words
Apparatus as described in claim 5 additionally including means for relative rotation between said first and second planar elements about an axis substantially perpendicular to said first and second planar elements.
Claim 8
Dependent Claim
31 words
Apparatus as described in claim 6 additionally including means for relative translation between said first and second planar elements along an axis substantially perpendicular to said first and second planar elements.
Claim 9
Dependent Claim
36 words
Apparatus as described in claim 7 wherein said apparatus is arranged such that circular interference rings are formed at said viewing means about a center lying on a line joining centers of said Fresnel zone plates.
Claim 10
Dependent Claim
23 words
Apparatus as described in claim 8 additionally including means for weakly converging said collimated light prior to incidence on said Fresnel zone plates.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1985-11-22 | 1986-05-24 | 1986-11-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-11-22 | 1990-05-24 | 1990-11-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-11-22 | 1994-05-24 | 1994-11-23 | $7700.00 | Window Closed / Lapsed |