Patent EP0138610A2 successfully refreshed from Google Patents.
EP0138610A2
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EP
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Electron detector
Assignee: Texas Instruments Ltd
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Filing: 1984-10-16
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Granted: —
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Expires: 2004-10-16
Abstract
Abstract Secondary electrons emitted by a body under electron beam bombardment into the magnetic field of a magnetic electron lens in which the body is placed are constrained and directed by the magnetic field so that the lens either focusses them to a small region at the centre of a hemispherical collector assembly so that the direction of the electrons do not affect their angle of incidence on the collector, or brings their paths to be within a small angle (5°) of the axis of the lens so that they impinge on a plane collector substantially normally. The invention is of particular value in the electron beam inspection of an integrated circuit when operating.
Inventors
- 👤 Simon Christopher John Garth
- 👤 William Charles Nixon
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 11:07
CPC Classifications
H; H01; H01J; H01J37/00; H01J37/02; H01J37/244; G; G01; G01R; G01R31/00; G01R31/28; G01R31/302; G01R31/305; H01J37/04; H01J37/05; H01J2237/00; H01J2237/05; H01J2237/053; H01J2237/244; H01J2237/2443; H01J2237/2448; H01J2237/2449; H01J2237/245; H01J2237/24507
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
104 words
An electron detector for detecting secondary electrons emitted from a body bombarded by an electron beam, the detector having a magnetic lens, the magnetic field of which is such that the secondary electrons are constrained and directed by the magnetic field to a collector assembly having retarding grid means, and wherein the-collector assembly is so constructed and the magnetic lens is so arranged relatively thereto to control the paths of the secondary electrons so that they approach the retarding grid means of the collector assembly at a sufficiently small angle to the normal that their approach speeds are substantially equal to their actual speeds.
Claim 2
Dependent Claim
104 words
An electron detector for detecting secondary electrons emitted from a body bombarded by an electron beam, the detector having a magnetic lens, the magnetic field of which is such that the secondary electrons are constrained and directed by the magnetic field to a collector assembly having retarding grid means, and wherein the-collector assembly is so constructed and the magnetic lens is so arranged relatively thereto to control the paths of the secondary electrons so that they approach the retarding grid means of the collector assembly at a sufficiently small angle to the normal that their approach speeds are substantially equal to their actual speeds.
Claim 3
Dependent Claim
47 words
A detector according to claim 1 wherein the magnetic lens is axially symmetrical, the body is located on the axis and the electron beam is passed through the magnetic lens in one direction and the secondary electrons are passed through the magnetic lens in the opposite direction.
Claim 4
Dependent Claim
46 words
A detector according to claim 1 or 2 wherein electrode means are provided close to or within the magnetic lens for attracting secondary electrons emitted by the body and accelerating them and then retarding them to their emission speeds on their passage through the magnetic lens.
Claim 5
Dependent Claim
55 words
A detector according to claim 1, 2 or 3 wherein the magnetic lens is arranged to focus the secondary electrons to a small region and the collector assembly is of part-spherical form centred on the small region so that the secondary electrons approach the retarding.grid means of the collector assembly in a substantially normal direction.
Claim 6
Dependent Claim
35 words
A detector according to claim 4 wherein the collector assembly is of hemispherical form with a collection region between two concentric hemispherical electrodes and includes electron responsive means of annular form bounding the collection region.
Claim 7
Dependent Claim
133 words
A detector according to claim 1, 2 or 3 wherein the magnetic lens is arranged so that the body is located near the region of maximum field strength of the lens such that the secondary electrons are constrained by the lens field to move through a weakening field to a region of substantially constant field strength considerably weaker than the maximum field strength, the retarding grid means being planar and located in the region with the axis normal to it, the arrangement being such that secondary electrons emitted by the body follow helical paths about the axis, which paths become progressively elongated.as the distance from the body increases so that in the region of substantially constant field strength the electron paths are at small angles to the normal to the retarding grid means.
Claim 8
Dependent Claim
72 words
A detector according to claim 6, wherein the magnetic lens has a core of magnetisable material in the form of a cylindrical pot tapering inwardly at its upper end and closed at its bottom end with a central pillar projecting upwardly from the bottom end and an optional annular disc extending from the wall just above the top of the pillar, the lens being energised by a winding around the central pil)ar.
Claim 9
Dependent Claim
69 words
A detector according to claim 7, including a tube aligned with the pillar extending through the upper part of the cylindrical pot, and projecting from its upp end, the tube supporting the electrode means for accelerating and retarding the secondary electrons emitted by the body, the retarding grid means and an additional winding for producing the region of substantially constant field strength at the upper end of the tube.
Claim 10
Dependent Claim
19 words
A detector according to claim 7 or 8, wherein the body is located at the top of the pillar.
Claim 11
Dependent Claim
26 words
A detector according to any one of claims 6 to 9, wherein the collector assembly is located off the axis and has an electron attracting electrode.
Claim 12
Dependent Claim
42 words
A detector according to claim 5 or 10 wherein the electron responsive means produces light in response to electrons impinging on it and a photomultiplier is provided to receive light from the electron responsive means and to produce a corresponding output signal.
Claim 13
Dependent Claim
19 words
A detector as claimed in any one of the preceding claims in which the body is an integrated circuit.
Claim 14
Dependent Claim
32 words
A detector as claimed in claim 12 in which means are provided for connecting the integrated circuit in an operational manner and for maintaining it in operation during the electron beam bombardment.
Claim 15
Dependent Claim
56 words
. A method of testing an integrated circuit whilst in an operational mode comprising the steps of bombarding at least a part of the circuit with an electron beam, constraining secondary electrons emitted as a result of said bombardment by a magnetic field to follow paths that terminate in substantially normal directions on a retarding grid.
Claim 16
Dependent Claim
56 words
. A method of testing an integrated circuit whilst in an operational mode comprising the steps of bombarding at least a part of the circuit with an electron beam, constraining secondary electrons emitted as a result of said bombardment by a magnetic field to follow paths that terminate in substantially normal directions on a retarding grid.
Claim 17
Dependent Claim
53 words
A method as claimed in claim 14 and further comprising the steps of exposing the integrated circuit to a magnetic field of maximum intensity and so constraining the secondary electrons that they move through a weakening magnetic field of substantially constant field strength that is considerably weaker than the said maximum field strength.
Claim 18
Dependent Claim
51 words
A method as claimed in claim 14 in which the secondary electrons are so constrained as to follow helical paths which become progressively more elongated as the distance from the integrated circuit increases and which then lie about an axis that is substantially normal to the surface of the retarding grid.
Claim 19
Independent Claim
23 words
A method of testing an integrated circuit substantially as herein described with reference to Fig. 1 or Fig. 2 of the accompanying drawings.
Claim 20
Independent Claim
23 words
A method of testing an integrated circuit substantially as herein described with reference to Fig. 1 or Fig. 2 of the accompanying drawings.
Claim 21
Dependent Claim
22 words
An electron detector substantially as described herein with reference to and as illustrated by Figure 1 or 2 of the accompanying drawings.
Claim 22
Dependent Claim
22 words
An electron detector substantially as described herein with reference to and as illustrated by Figure 1 or 2 of the accompanying drawings.
References Cited (Backward Citations)
No citation records indexed.
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