US4554458A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electron beam projection lithography
Assignee: International Business Machines Corp
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Filing: 1984-07-20
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Granted: 1985-11-19
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Expires: 2004-07-20
Abstract
Abstract The photoresist film 12 on the surface of a wafer 11 is exposed through the shadow pattern which is generated by a transmission mask 13 arranged a short distance therefrom when the mask is subjected to a large-area electron beam. The source of the electron beam is an unstructured photocathode 16 on an ultraviolet transparent carrier such as, quartz glass 17 which is subjected to UV radiation from the backside. The electrons exiting from layer 16 are accelerated by a homogeneous electric field 14 towards the mask 13 and shaped to form a homogeneous collimated electron beam. By means of laterally positioned electrostatic deflecting electrodes 19a, 19b, the entire electron beam can be tilted relative to the wafer for adjusting the mask pattern.
Inventors
- 👤 Uwe Behringer
- 👤 Harald Bohlen
- 👤 Werner Kulcke
- 👤 Peter Nehmiz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 20:10
CPC Classifications
H; H01; H01J; H01J37/00; H01J37/30; H01J37/317; H01J37/3174; H01J37/3175; B; B82; B82Y; B82Y10/00; B82Y40/00; H01J37/3002; H01J37/3007; H01J2237/00; H01J2237/06; H01J2237/063; H01J2237/06325; H01J2237/06333; H01J2237/15; H01J2237/151; H01J2237/30; H01J2237/317; H01J2237/3175; H01J2237/31777; H01J2237/31788
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
122 words
Apparatus for exposing a resist-coated wafer to a predetermined pattern of electrons, comprising; a. A source of ultraviolet radiation; b. A photoemissive cathode having a substrate transparent to U.V. radiation and a homogeneaus photoemissive coating on the substrate surface facing away from said source, and illuminated thereby, wherein the surface of said wafer coated with resist faces said cathode; and c. An apertured mask having an aperture with a pattern of electron transparent and opaque regions corresponding to said predetermined pattern, the said mask being positioned spaced apart from the photemissive cathode and closely adjacent to said resist surface; whereby the patterned beam of electrons passed by said mask will selectively alter the state of said resist to replicate said predetermined pattern.
Claim 2
Dependent Claim
122 words
Apparatus for exposing a resist-coated wafer to a predetermined pattern of electrons, comprising; a. A source of ultraviolet radiation; b. A photoemissive cathode having a substrate transparent to U.V. radiation and a homogeneaus photoemissive coating on the substrate surface facing away from said source, and illuminated thereby, wherein the surface of said wafer coated with resist faces said cathode; and c. An apertured mask having an aperture with a pattern of electron transparent and opaque regions corresponding to said predetermined pattern, the said mask being positioned spaced apart from the photemissive cathode and closely adjacent to said resist surface; whereby the patterned beam of electrons passed by said mask will selectively alter the state of said resist to replicate said predetermined pattern.
Claim 3
Dependent Claim
25 words
The apparatus of claim 1 wherein means are provided to produce a potential difference between said cathode and said wafer to collimate said electron beam.
Claim 4
Dependent Claim
22 words
The apparatus of claim 1 or 2 wherein the area of said photocathode is substantially coextensive with the apertures in said mask.
Claim 5
Dependent Claim
22 words
The apparatus of claim 3 wherein the areas of the cathode, the apertures in said mask, and the wafer are substantially coextensive.
Claim 6
Dependent Claim
58 words
The apparatus of claim 3 wherein the area of the wafer is substantially greater than the areas of said apertures and said photocathode, and means are provided for imparting relative motion between said wafer and said mask, whereby discrete areas of said wafer are successively exposed to the patterned electron beam passed by the apertures in said mask.
Claim 7
Independent Claim
36 words
The apparatus as defined in claims 1 or 2 wherein means are provided for applying a potential difference to said mask substantially equal to the value of the potential gradient at the location of the mask.
Claim 8
Dependent Claim
17 words
The apparatus of claim 1 or 2 wherein deflection plates are provided to deflect said electron beam.
References Cited (Backward Citations)
US3832561A
Cited
US4460831A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-11-18 | 1989-05-20 | 1989-11-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-11-18 | 1993-05-20 | 1993-11-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-11-18 | 1997-05-20 | 1997-11-19 | $7700.00 | Window Closed / Lapsed |