US3615449A
Expired / Lapsed
US
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Method of generating high area-density periodic arrays by diffraction imaging
Assignee: RCA Corp
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Filing: 1969-09-25
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Granted: 1971-10-26
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Expires: 1989-09-25
Abstract
Abstract High area-density arrays, such as diode array vidicon camera tube targets and electron tube electrode screens, are made by photolithographic printing utilizing a photomask diffraction image rather than a photomask shadow for exposing a photoresist masking layer. To form the masking layer, a relatively flat photoresist layer is exposed to a periodic array diffraction image from a photomask. The exposed portions of the layer are removed, leaving an array of unexposed portions. Alternatively, the unexposed portions of the layer may be removed, leaving an array of exposed portions. During the exposure, the layer is oscillated over a distance of essentially one-quarter the wavelength of the light and in a direction substantially perpendicular to the surface of the layer to avoid the appearance of interference fringe patterns after development.
Inventors
- 👤 David Leslie Greenaway
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 06:17
CPC Classifications
H; H10; H10F; H10F39/00; H10F39/10; H10F39/107; G; G03; G03F; G03F7/00; G03F7/20; G03F7/2002; G03F7/201; G03F7/70; G03F7/70216; G03F7/70358; H01; H01J; H01J29/00; H01J29/02; H01J29/10; H01J29/36; H01J29/39; H01J29/45; H01J29/451; H01J29/453; H01J29/455; H01J9/00; H01J9/20; H01J9/233; H10D; H10D99/00; H10P; H10P76/00; H10P76/20; H10P76/204; H10P76/2041; H10P76/2042; Y; Y10; Y10S; Y10S359/00; Y10S359/90
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
21 words
The method defined in claim 1 and wherein said layer is exposed to a coherent, periodic array, planar light diffraction image.
Claim 2
Dependent Claim
16 words
The method defined in claim 1 wherein said substrate surface is a relatively flat semiconductor surface.
Claim 3
Dependent Claim
21 words
The method defined in claim 3 and wherein said substrate surface is a major surface of a silicon vidicon target substrate.
Claim 4
Independent Claim
63 words
A method of forming a periodic array of material, comprising the steps of: b. covering a substrate surface with a layer of photosensitive material; b. exposing said layer directly to a periodic array diffraction image from a photomask, thereby forming exposed portions and unexposed portions of said layer, and c. removing said exposed portions of said layer, leaving an array of unexposed material.
Claim 5
Dependent Claim
30 words
The method defined in claim 5 and wherein said diffraction image is formed by passing collimated light through a photomask disposed perpendicularly to the direction of collimation of said light.
Claim 6
Dependent Claim
12 words
The method defined in claim 6 and wherein said light is coherent.
Claim 7
Dependent Claim
18 words
The method defined in claim 6 and wherein said light for forming said diffraction image is essentially monochromatic.
Claim 8
Dependent Claim
36 words
The method defined in claim 8 and comprising the step of moving said surface during said exposing for at least a distance of one-quarter wavelength of said coherent light in a direction perpendicular to said surface.
Claim 9
Independent Claim
63 words
A method of forming a periodic array of material, comprising the steps of: a. covering a substrate surface with a layer of photosensitive material; b. exposing said layer directly to a periodic array diffraction image from a photomask, thereby forming exposed portions and unexposed portions of said material, and c. removing said unexposed portion of said layer, leaving an array of exposed material.
Claim 10
Independent Claim
88 words
A method of fabricating a thin screen of a material, comprising: a. covering a major surface of a sheet of said material with a photoresist coating; b. exposing said photoresist coating to a diffraction image from a periodic array photomask; c. developing said photoresist to form a masking layer of said photoresist having the same periodicity as said diffraction image, said mesh of photoresist having interstices through which portions of said sheet are exposed, and d. etching away said exposed portions of said sheet to form a screen.
Claim 11
Dependent Claim
20 words
The method defined in claim 11 and including the step of removing said mesh of said photoresist from said screen.
Claim 12
Dependent Claim
58 words
The method defined in claim 11 and wherein: said sheet is of metal having a thickness less than 0.01 inch; said diffraction image is formed by passing collimated, essentially monochromatic light through a flat photomask having a regular pattern of openings, said photomask being disposed perpendicularly to said collimated light; said masking layer is removed after said etching.
Claim 13
Dependent Claim
38 words
The method defined in claim 13 and comprising the step of moving said surface at least once for a distance of one-quarter wavelength of said coherent light in a direction perpendicular to said surface during said exposing step.
Claim 14
Independent Claim
262 words
A method of fabricating a camera tube target, comprising: a. providing a semiconductor substrate of a first conductivity type; b. covering said substrate with an insulating layer; c. covering said insulating layer with a first photoresist layer; d. exposing said first photoresist layer to a first diffraction image from a periodic array photomask; e. developing said first photoresist layer to form in it an array of openings corresponding to said diffraction image, said openings exposing said insulating layer; f. etching away said insulating layer in said openings to expose discrete regions of said substrate in said openings; g. covering said insulating layer and said substrate in said openings with a doping layer containing a dopant for converting said discrete regions of said substrate to a second conductivity type; h. covering said doping layer with a second photoresist layer; i. exposing said second photoresist layer to a second diffraction image from said photomask, said second image being in registry with said openings; j. developing said second photoresist layer to form an array of photoresist pads in registry with said openings, each of said pads being superimposed on and completely covering a single one of said openings; k. etching away said doping layer between said photoresist pads to form an array of doping layer pads under said photoresist pads; l. removing said photoresist pads; and m. driving said dopant from said doping layer into said substrate in said discrete regions of said substrate to change the conductivity type of said discrete regions and to form PN junctions between said discrete regions and said substrate.
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) | 1974-10-25 | 1975-04-26 | 1975-10-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-10-25 | 1979-04-26 | 1979-10-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-10-25 | 1983-04-26 | 1983-10-26 | $7700.00 | Window Closed / Lapsed |