US4392058A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electron beam lithography
Assignee: National Research Development Corp UK
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Filing: 1981-08-03
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Granted: 1983-07-05
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Expires: 2001-08-03
Abstract
Abstract In electron beam lithography apparatus a substrate, on which an exposure pattern is to be produced, is exposed to a plurality of electron beams. In a double beam arrangement one beam is capable of the highest resolution required and has a necessarily low writing speed. The other beam is relatively coarse in beam width but carries a higher current and has a much higher writing speed. Single-pole magnetic lens focusing is used with close angular spacing between the beams. Scanning of the pattern is programmed for economy of time so that the beams produce complementary portions of the pattern, the fine beam defining for example the edges of a structure while the coarse beam scans the area bounded by the edges. Scanning may be simultaneous or sequential. Selection of the relative values of beam potential and the use of energy selective detectors enable the two scanned regions to be imaged.
Inventors
- 👤 Kenneth C. A. Smith
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 12:38
CPC Classifications
B; B82; B82Y; B82Y40/00; H; H05; H05K; H05K3/00; H05K3/0073; H05K3/0082; B82Y10/00; H01; H01J; H01J37/00; H01J37/30; H01J37/317; H01J37/3174; H01J37/3177; H05K2203/00; H05K2203/09; H05K2203/092
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
45 words
An apparatus for electron beam lithography comprising: means for presenting a substrate for exposure of a desired pattern such that each of a plurality of elemental areas of the substrate is presented in succession for exposure during a respective exposure interval at a single location;
Claim 2
Independent Claim
45 words
An apparatus for electron beam lithography comprising: means for presenting a substrate for exposure of a desired pattern such that each of a plurality of elemental areas of the substrate is presented in succession for exposure during a respective exposure interval at a single location;
Claim 3
Dependent Claim
159 words
a plurality of electron guns, the axes of the guns being relatively inclined for substantial convergence at the substrate, the guns being independently operable to produce electron beams, at least a first gun being constructed and arranged to produce a fine electron beam and at least a second gun being constructed and arranged to produce a coarse electron beam; means for focusing each beam on the surface of the substrate, deflection means for deflecting the beams across the surface; and deflection control means operative to cause said deflection means to produce a portion of the desired exposure pattern which is required to be highly resolved by the continuous deflection of a fine one of said beams across the surface and a different portion of the desired exposure pattern which is required to be less highly resolved by the continuous deflection of a coarse one of said beams across the surface in the elemental area presented during said exposure interval.
Claim 4
Dependent Claim
159 words
a plurality of electron guns, the axes of the guns being relatively inclined for substantial convergence at the substrate, the guns being independently operable to produce electron beams, at least a first gun being constructed and arranged to produce a fine electron beam and at least a second gun being constructed and arranged to produce a coarse electron beam; means for focusing each beam on the surface of the substrate, deflection means for deflecting the beams across the surface; and deflection control means operative to cause said deflection means to produce a portion of the desired exposure pattern which is required to be highly resolved by the continuous deflection of a fine one of said beams across the surface and a different portion of the desired exposure pattern which is required to be less highly resolved by the continuous deflection of a coarse one of said beams across the surface in the elemental area presented during said exposure interval.
Claim 5
Independent Claim
225 words
An apparatus for electron beam lithography comprising: means for presenting a substrate for exposure of a desired pattern such that each of a plurality of elemental areas of the substrate is presented in succession for exposure at each of a plurality of locations during a respective exposure interval; a plurality of electron guns, the axes of the guns being relatively inclined for substantial convergence at the substrate, the guns being independently operable to produce electron beams, at least a first gun being constructed and arranged to produce a fine electron beam and at least a second gun being constructed and arranged to produce a coarse electron beam; means for focusing each beam on the surface of the substrate, and deflection means for deflecting the beams across the surface; and deflection control means operative to cause said deflection means to produce a portion of the desired exposure pattern which is required to be highly resolved by the continuous deflection of a fine one of said beams across the surface in the elemental area presented at one of said locations and a different portion of the desired exposure pattern which is required to be less highly resolved by the continuous deflection of a coarse one of said beams across the surface in the elemental area presented at a different one of said locations during said exposure interval.
Claim 6
Independent Claim
225 words
An apparatus for electron beam lithography comprising: means for presenting a substrate for exposure of a desired pattern such that each of a plurality of elemental areas of the substrate is presented in succession for exposure at each of a plurality of locations during a respective exposure interval; a plurality of electron guns, the axes of the guns being relatively inclined for substantial convergence at the substrate, the guns being independently operable to produce electron beams, at least a first gun being constructed and arranged to produce a fine electron beam and at least a second gun being constructed and arranged to produce a coarse electron beam; means for focusing each beam on the surface of the substrate, and deflection means for deflecting the beams across the surface; and deflection control means operative to cause said deflection means to produce a portion of the desired exposure pattern which is required to be highly resolved by the continuous deflection of a fine one of said beams across the surface in the elemental area presented at one of said locations and a different portion of the desired exposure pattern which is required to be less highly resolved by the continuous deflection of a coarse one of said beams across the surface in the elemental area presented at a different one of said locations during said exposure interval.
Claim 7
Independent Claim
137 words
A method of electron beam lithography comprising the steps of: presenting in succession a plurality of elemental areas of a substrate for the exposure of a desired pattern during respective exposure intervals; producing a plurality of electron beams from a respective plurality of electron guns independently of each other, the axes of the electron guns being relatively inclined so that the electron beams are relatively inclined for substantial convergence at the substrate and including at least one fine beam and at least one coarse beam; focusing each beam on the surface of the substrate; and continuously deflecting the beams across the surface such that a fine one of said beams produces a portion of the desired exposure pattern which is required to be less highly resolved in one of the elemental areas during a single exposure interval.
Claim 8
Independent Claim
137 words
A method of electron beam lithography comprising the steps of: presenting in succession a plurality of elemental areas of a substrate for the exposure of a desired pattern during respective exposure intervals; producing a plurality of electron beams from a respective plurality of electron guns independently of each other, the axes of the electron guns being relatively inclined so that the electron beams are relatively inclined for substantial convergence at the substrate and including at least one fine beam and at least one coarse beam; focusing each beam on the surface of the substrate; and continuously deflecting the beams across the surface such that a fine one of said beams produces a portion of the desired exposure pattern which is required to be less highly resolved in one of the elemental areas during a single exposure interval.
Claim 9
Dependent Claim
17 words
Apparatus according to claim 1 or claim 2 in which the first gun has a field-emission cathode.
Claim 10
Dependent Claim
14 words
Apparatus according to claim 4 in which the second gun has a field-emission cathode.
Claim 11
Dependent Claim
33 words
Apparatus according to claim 4 in which each gun includes an appropriate beam-limiting aperture, the apertures being interchangeable to enable the positions of the fine beam and the coarse beam to be interchanged.
Claim 12
Dependent Claim
39 words
Apparatus according to claim 1 or claim 2 in which the means for focusing at least one of the beams comprises a single-pole magnetic lens having a pole-piece nose which extends along the relevant beam axis towards the cathode.
Claim 13
Dependent Claim
22 words
Apparatus according to claim 7 in which such a single-pole lens is arranged externally of the vacuum enclosure adjacent the relevant cathode.
Claim 14
Dependent Claim
26 words
Apparatus according to claim 7 in which such a single-pole lens is arranged externally of the vacuum enclosure adjacent the relevant elemental area of the substrate.
Claim 15
Dependent Claim
51 words
Apparatus according to claim 1 or claim 2 in which the deflection means for a beam directed normally to the substrate comprises deflection means arranged to enable the angle of deflection to be selected for a desired deflection area and normal incidence at the substrate to be substantially maintained during deflection.
Claim 16
Dependent Claim
40 words
Apparatus according to claim 1 or claim 2 including means for detecting electrons scattered from the area of the substrate scanned by one of the beams, the or each other beam being suppressed, to enable that area to be imaged.
Claim 17
Dependent Claim
51 words
Apparatus according to claim 11 in which at least one of the other beams is accelerated to a potential different from that of said one of the beams and comprising energy selective electron detection means effective to distinguish electrons scattered from the scanned areas, to enable those areas to be imaged.
Claim 18
Dependent Claim
65 words
Apparatus according to claim 1 or claim 2 having a fine beam to define an edge of an exposure pattern in which the beam is inclined to a normal to the substrate surface, the inclination being such that after passing the edge, the projection on the surface of the path of the beam in the substrate lies within the exposure area bounded by the edge.
Claim 19
Dependent Claim
36 words
Apparatus according to claim 13 in which each edge of an exposure pattern is thus defined and a coarse beam is provided at normal incidence to the substrate to complete the exposure within the defined edges.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-07-04 | 1987-01-03 | 1987-07-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-07-04 | 1991-01-03 | 1991-07-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-07-04 | 1995-01-03 | 1995-07-05 | $7700.00 | Window Closed / Lapsed |