US3748975A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus for and method of correcting a defective photomask
Assignee: RCA Corp
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Filing: 1972-01-03
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Granted: 1973-07-31
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Expires: 1992-01-03
Abstract
Abstract A defect, in a metal photomask, that is either to be etched away, if opaque, or to be rendered opaque, if light-transmitting, is corrected, with the aid of novel apparatus, in a novel method of: (a) depositing a photoresist coating over a patterned film on one surface of the photomask, (b) focusing a projected shaped beam of light, incapable of exposing the photoresist coating, onto the photoresist coating, (c) aligning the focused beam, by viewing it from a surface of the photomask opposite to that which the photoresist coating is on, so that the light overlays the defect, (d) changing the characteristics of the beam of light so as to expose the photoresist coating, and (e) developing the photoresist coating. Depending upon the kind of photoresist coating used, the defect can now be either etched away or rendered opaque.
Inventors
- 👤 M Tarabocchia
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 17:45
CPC Classifications
G; G03; G03F; G03F1/00; G03F1/68; G03F1/72
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
109 words
Apparatus for correcting a defective photomask, said photomask comprising a transparent substrate having opposite surfaces, a patterned opaque film being on one of said opposite surfaces, and having a photoresist coating over said film, said apparatus comprising: means to project a shaped beam of light, having characteristics such that it does not expose said photoresist coating, and to focus it on said photoresist coating, means to align said focused beam of light over a defect in said defective photomask when viewing said transparent substrate from the other of said opposite surfaces, and means for changing the characteristics of said beam of light so that it exposes said photoresist coating.
Claim 2
Dependent Claim
109 words
Apparatus for correcting a defective photomask, said photomask comprising a transparent substrate having opposite surfaces, a patterned opaque film being on one of said opposite surfaces, and having a photoresist coating over said film, said apparatus comprising: means to project a shaped beam of light, having characteristics such that it does not expose said photoresist coating, and to focus it on said photoresist coating, means to align said focused beam of light over a defect in said defective photomask when viewing said transparent substrate from the other of said opposite surfaces, and means for changing the characteristics of said beam of light so that it exposes said photoresist coating.
Claim 3
Dependent Claim
64 words
Apparatus for correcting a defective photomask as described in claim 1, wherein: said means to project a shaped beam of light comprises a source of ultraviolet light, an uLtraviolet absorption filter, and means to attenuate the intensity of said source between said source and said filter, whereby said beam of light comprises wavelengths and an intensity to which said photoresist coating is substantially insensitive.
Claim 4
Dependent Claim
26 words
Apparatus for correcting a defective photomask as described in claim 2, wherein: said means to attenuate the intensity of said source comprises a fiber optic bundle.
Claim 5
Dependent Claim
59 words
Apparatus for correcting a defective photomask as described in claim 2, wherein: said means to project a shaped beam of light also comprises adjustable means to provide a pair of transversely disposed adjustable slits in the path of said beam of light, whereby said beam of light can be focused on said photoresist coating as a rectangular light image.
Claim 6
Dependent Claim
68 words
Apparatus for correcting a defective photomask as described in claim 1, wherein: said means to align said focused beam of light comprises a microscope viewing system having means to illuminate said other of said opposite surfaces of said photomask by reflective light of wavelengths substantially different from those of said beam of light which does not expose said photoresist coating, and an eyepiece lens assembly having reference markings.
Claim 7
Dependent Claim
56 words
Apparatus for correcting a defective photomask as described in claim 1, wherein: said means for changing the characteristics of said beam of light comprises means for increasing the intensity of said beam and means for changing the wavelengths of said beam so that said photoresist coating is responsive to it, whereby to expose said photoresist coating.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-07-30 | 1977-01-29 | 1977-07-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-07-30 | 1981-01-29 | 1981-07-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-07-30 | 1985-01-29 | 1985-07-31 | $7700.00 | Window Closed / Lapsed |