Patent US4680468A successfully refreshed from Google Patents.
US4680468A
Expired / Lapsed
US
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Particle detector
Assignee: National Research Council Canada
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Filing: 1985-08-05
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Granted: 1987-07-14
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Expires: 2005-08-05
Abstract
Abstract A detector for charged particles, i.e. secondary electons ir ions emitted from a bombardment area of a specimen in an instrument such as a scanning electron microscope or analytical instrument, consists of a collector, e.g. a scintillation surface highly charged with a voltage of the opposite polarity from that of the particles, for receiving the particles and providing an output proportional to the number thereof. A grid, charged with a voltage of the same sign as the scintillation surface, but to a lower value, is located between the scintillation surface and the bombardment area, and a probe in the form of a wire electrically connected to the grid projects into the vicinity of the bombardment area which is in a confined space between the specimen and the instrument. The result is to set up an electrostatic field around the wire, causing a significant number of the charged particles to orbit the wire and travel to the scintillation surface. The detector has better performance in situations requiring a relatively long "reach" into a confined space than has been attainable with previously known detectors. As a result, the detector is especially useful when the speciment under examination is relatively large, e.g. a large silicon wafer.
Inventors
- 👤 Claude Bouchard
- 👤 Pierre Boulanger
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 23:07
CPC Classifications
H; H01; H01J; H01J37/00; H01J37/02; H01J37/244; H01J2237/00; H01J2237/244; H01J2237/2443; H01J2237/2448; H01J2237/2449; H01J2237/245; H01J2237/24507
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
180 words
A detector for detecting secondary charged particles emitted by an area of a specimen in response to particle beam bombardment thereof, said area being located in a confined space, said detector comprising (a) means including a particle detecting device for providing an output proportional to the number of said secondary charged particles received by such device, (b) means for applying to the particle detecting device a first voltage of opposite sign to that of the charge on the secondary particles, (c) a grid located between the detecting device and the bombardment area, (d) means for applying to the grid a second voltage no greater than, and of the same sign as, the first voltage, and (e) an elongate probe projecting into the vicinity of said bombardment area in said confined space, and (f) means for applying to the probe a third voltage no greater than, and of the same sign as, the second voltage whereby to set up an electrostatic field around said probe to cause said secondary charged particles to orbit the probe and travel to the detecting device.
Claim 2
Dependent Claim
180 words
A detector for detecting secondary charged particles emitted by an area of a specimen in response to particle beam bombardment thereof, said area being located in a confined space, said detector comprising (a) means including a particle detecting device for providing an output proportional to the number of said secondary charged particles received by such device, (b) means for applying to the particle detecting device a first voltage of opposite sign to that of the charge on the secondary particles, (c) a grid located between the detecting device and the bombardment area, (d) means for applying to the grid a second voltage no greater than, and of the same sign as, the first voltage, and (e) an elongate probe projecting into the vicinity of said bombardment area in said confined space, and (f) means for applying to the probe a third voltage no greater than, and of the same sign as, the second voltage whereby to set up an electrostatic field around said probe to cause said secondary charged particles to orbit the probe and travel to the detecting device.
Claim 3
Dependent Claim
13 words
A detector according to claim 1, wherein said probe comprises a thin wire.
Claim 4
Dependent Claim
25 words
A detector according to claim 1, wherein said probe extends in a direction that is orthogonal to and intersects the axis of said particle beam.
Claim 5
Dependent Claim
33 words
A detector according to claim 1, wherein said probe extends in a direction that makes a small angle with a direction that is orthogonal to and intersects the axis of said particle beam.
Claim 6
Dependent Claim
18 words
A detector according to claim 4, wherein said angle is approximately in the range of 2° to 3°.
Claim 7
Dependent Claim
29 words
A detector according to claim 1, wherein said probe is supported at one end by the grid while being electrically insulated therefrom, and is self supporting throughout its length.
Claim 8
Dependent Claim
15 words
A detector according to claim 1, wherein said probe is electrically common with the grid.
Claim 9
Dependent Claim
24 words
A detector according to claim 7, wherein said probe is supported at one end by the grid and is self supporting throughout its length.
Claim 10
Dependent Claim
68 words
A detector according to claim 1, including a protective tube surrounding the probe, said tube being supported at one end by the grid while being electrically insulated therefrom and the probe being supported at its remote end by the tube while being electrically insulated therefrom, and means for maintaining the tube at a ground potential or at a potential of the same sign as the secondary charged particles.
Claim 11
Dependent Claim
30 words
A detector according to claim 1, wherein the instrument is a scanning electron microscope, the secondary charged particles are electrons and the particle detecting device and grid are positively charged.
Claim 12
Dependent Claim
43 words
A detector according to claim 10, wherein said particle detecting device is a scintillation surface and wherein sais scintillation surface is biased to a voltage of at least about 8 kV and the voltage on the grid is at least about 300 V.
Claim 13
Dependent Claim
13 words
A detector according to claim 10, wherein the probe comprises a thin wire.
Claim 14
Dependent Claim
22 words
A detector according to claim 10, wherein the probe comprises a plurality of wires extending parallel to each other and close together.
Claim 15
Dependent Claim
25 words
A detector according to claim 10, wherein the probe extends in a direction that is orthogonal to and intersects the axis of said particle beam.
Claim 16
Dependent Claim
33 words
A detector according to claim 10, wherein the probe extends in a direction that makes a small angle with a direction that is orthogonal to and intersects the axis of said particle beam.
Claim 17
Dependent Claim
18 words
A detector according to claim 15, wherein said angle is approximately in the range of 2° to 3°.
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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) | 1990-07-13 | 1991-01-12 | 1991-07-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-07-13 | 1995-01-12 | 1995-07-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-07-13 | 1999-01-12 | 1999-07-14 | $7700.00 | Window Closed / Lapsed |