Patent US4728790A successfully refreshed from Google Patents.
US4728790A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Low-abberation spectrometer objective with high secondary electron acceptance
Assignee: Advantest Corp
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Filing: 1987-04-21
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Granted: 1988-03-01
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Expires: 2007-04-21
Abstract
Abstract The spectrometer objective of the invention is composed of a short focal length objective lens (OL) and a spectrometer-detector arrangement which is completely integrated in the magnetic lens. The working distance (L) has a decisive influence on the chromatic and spherical image defect of the objective lens (OL) which can be reduced with the arrangement of the invention and, thus, the diameter of the electron probe on the specimen (PR) can be substantially demagnified. An angle-independent accumulation of the secondary electrons (SE) are triggered such that the measuring location occurs according to the invention by imaging of the virtual source point (QS) of the secondary electrons (SE) into the center of a spherical opposing field which occurs in the spatial region between two spherical-symmetrical grid electrodes (K1 and K2).
Inventors
- 👤 Erich Plies
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 21:40
CPC Classifications
G; G01; G01R; G01R31/00; G01R31/28; G01R31/302; G01R31/305; H; H01; H01J; H01J37/00; H01J37/02; H01J37/04; H01J37/10; H01J37/244; H01J37/26; H01J37/266; H01J37/268; H01J49/00; H01J49/02; H01J49/06; H01J49/44; H01J49/46; H01J49/48; H01J49/488; H01J2237/00; H01J2237/244; H01J2237/24485
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
229 words
A spectrometer for quantitative measurements of potentials in electron beam mensuration technology, comprising an electron beam source, an objective lens (OL) for focusing a primary electron beam (PE) from said source onto a specimen (PR), an electrostatic opposing field spectrometer which comprises an electrode arrangement (G1) for the extraction of secondary electrons (SE) triggered at the measuring location by the primary electron beam (PE), an electrode means (K1, K2) for generating an electrical opposing field which retards the secondary electrons (SE) from the specimen, and a detector for recording the secondary electrons (SE), characterized in that the opposing field electrode means comprises two spherical-symmetrical electrodes (K1, K2) which have potentials (V D , V E ) which are selected such that a spherical-symmetrical opposing field builds up in the space between said electrodes; the centers of said spherical-symmetrical electrodes (K1, K2) coincide at a point (ZS) which lies on the optical axis (OA) of the spectrometer objective above a pole shoe thereof; and said point (ZS) defines the center of the spherical-symmetrical opposing field and lies in a field-free space within the objective lens (OL) so that the secondary electrons (SE) are accelerated in the electrical field of the extraction electrode arrangement (G1) and are focused in the magnetic field of the objective lens (OL), such that they are focused into the center of the spherical-symmetrical opposing field (ZS).
Claim 2
Dependent Claim
229 words
A spectrometer for quantitative measurements of potentials in electron beam mensuration technology, comprising an electron beam source, an objective lens (OL) for focusing a primary electron beam (PE) from said source onto a specimen (PR), an electrostatic opposing field spectrometer which comprises an electrode arrangement (G1) for the extraction of secondary electrons (SE) triggered at the measuring location by the primary electron beam (PE), an electrode means (K1, K2) for generating an electrical opposing field which retards the secondary electrons (SE) from the specimen, and a detector for recording the secondary electrons (SE), characterized in that the opposing field electrode means comprises two spherical-symmetrical electrodes (K1, K2) which have potentials (V D , V E ) which are selected such that a spherical-symmetrical opposing field builds up in the space between said electrodes; the centers of said spherical-symmetrical electrodes (K1, K2) coincide at a point (ZS) which lies on the optical axis (OA) of the spectrometer objective above a pole shoe thereof; and said point (ZS) defines the center of the spherical-symmetrical opposing field and lies in a field-free space within the objective lens (OL) so that the secondary electrons (SE) are accelerated in the electrical field of the extraction electrode arrangement (G1) and are focused in the magnetic field of the objective lens (OL), such that they are focused into the center of the spherical-symmetrical opposing field (ZS).
Claim 3
Dependent Claim
76 words
A spectrometer according to claim 1, characterized in that, for generating a space in the inside of the objective lens which is free of electrical fields, the electrode arrangement (G1) for the extraction of the secondary electrons (SE) and said spherical-symmetrical electrode (K1) which is the closest to the specimen (PR) are electrically connected by a hollow cylinder (HZ) which is concentrically mounted relative to the optical axis (OA) and tapers in the pole shoe gap.
Claim 4
Dependent Claim
37 words
A spectrometer according to claims 1 or 2, characterized in that said electrode means (K1, K2) which builds up a spherical-symmetrical opposing field is arranged above the pole shoe in the inside of the objective lens (OL).
Claim 5
Dependent Claim
49 words
A spectrometer according to claims 1 or 2, characterized in that an annular secondary electron detector (DT) which is mounted concentrically relative to the optical axis is provided above the electrode means (K1, K2) in the inside of the objective lens (OL) which builds up the spherical-symmetrical opposing field.
Claim 6
Dependent Claim
42 words
A spectrometer according to claims 1 or 2 characterized in that a further secondary electron detector is provided above the annular secondary electron detector (DT) which is mounted concentrically relative to the optical axis in the inside of the objective lens (OL).
Claim 7
Dependent Claim
37 words
A spectrometer according to claims 1 or 2, characterized in that a buffer grid (BG) is provided between said electrode means (K1, K2) which builds up a spherical-symmetrical opposing field and the annular secondary electron detector (DT).
Claim 8
Dependent Claim
31 words
A spectrometer according to claim 1 or 2, characterized in that said electrode means (K1, K2) which builds up a spherical-symmetrical opposing field is arranged immediately above the objective lens (OL).
Claim 9
Dependent Claim
45 words
A spectrometer according to claim 7, characterized in that an arrangement (DE, DN) for the deflection and acceleration of the secondary electrons (SE) in the direction of a detector (DT) is provided above said electrode means (K1, K2) which builds up a spherical-symmetrical opposing field.
Claim 10
Dependent Claim
96 words
A spectrometer according to claim 8, characterized in that the arrangement (DE, DN) for the deflection and acceleration of the secondary electrons (SE) in the direction of a detector (DT) comprises a grid electrode (DN) lying at positive potential (V DN ) and a deflection electrode (DE) which is arranged symmetrically thereto and has a negative potential, said grid electrode and said deflection electrode forming, together with the housing (GH) situated between these electrodes (DE, DN), the generated surface of a hollow cylinder which has an axis of symmetry which coincides with the optical axis (OA).
Claim 11
Dependent Claim
50 words
A spectrometer according to claim 9, characterized in that a buffer grid (BG) is provided between said electrode means (K1, K2) which builds up a spherical-symmetrical opposing field and the arrangement (DE, DN) for the deflection and acceleration of the secondary electrons (SE) in the direction of a detector (DT).
Claim 12
Dependent Claim
138 words
A spectrometer for quantitative electron beam measurements comprising an objective lens for focusing a primary electron beam from an electron beam source onto a specimen, a retarding potential spectrometer which comprises a first electrode arrangement for the acceleration of secondary particles triggered at said specimen in the direction of said objective lens, a second electrode arrangement for the deceleration of said secondary particles, said second electrode arrangement comprises two spherical-symmetrical electrodes which have different potentials; the center points of these electrodes coincide in a point lying on the optical axis of said objective lens above pole shoes thereof, and said point defines the center of the spherical-symmetrical retarding field and lies in a spatial region within the objective lens that is free of electrical fields and such point coincides with the focus point of the accelerated secondary particles.
Claim 13
Dependent Claim
138 words
A spectrometer for quantitative electron beam measurements comprising an objective lens for focusing a primary electron beam from an electron beam source onto a specimen, a retarding potential spectrometer which comprises a first electrode arrangement for the acceleration of secondary particles triggered at said specimen in the direction of said objective lens, a second electrode arrangement for the deceleration of said secondary particles, said second electrode arrangement comprises two spherical-symmetrical electrodes which have different potentials; the center points of these electrodes coincide in a point lying on the optical axis of said objective lens above pole shoes thereof, and said point defines the center of the spherical-symmetrical retarding field and lies in a spatial region within the objective lens that is free of electrical fields and such point coincides with the focus point of the accelerated secondary particles.
Claim 14
Dependent Claim
165 words
A spectrometer for quantitative electron beam measurements comprising an objective lens for focusing a primary electron beam from an electron beam source onto a specimen, a retarding potential spectrometer which comprises a first electrode arrangement for the acceleration of secondary particles triggered at said specimen in the direction of said objective lens, a second electrode arrangement for the deceleration of said secondary particles, said second electrode arrangement comprises two electrodes that form parts of the surface of two spheres having different radii; and these electrodes have potential such that a spherical-symmetrical retarding field is built up in the spatial region between said electrodes; the center points of said two electrodes coincide in a point lying on the optical axis of the objective lens above pole shoes; and said point defining the center of the spherical-symmetrical retarding field lies within a spatial region within the spectrometer objective lens that is free of electrical fields and said point coincides with the focus point of the secondary particles.
Claim 15
Dependent Claim
165 words
A spectrometer for quantitative electron beam measurements comprising an objective lens for focusing a primary electron beam from an electron beam source onto a specimen, a retarding potential spectrometer which comprises a first electrode arrangement for the acceleration of secondary particles triggered at said specimen in the direction of said objective lens, a second electrode arrangement for the deceleration of said secondary particles, said second electrode arrangement comprises two electrodes that form parts of the surface of two spheres having different radii; and these electrodes have potential such that a spherical-symmetrical retarding field is built up in the spatial region between said electrodes; the center points of said two electrodes coincide in a point lying on the optical axis of the objective lens above pole shoes; and said point defining the center of the spherical-symmetrical retarding field lies within a spatial region within the spectrometer objective lens that is free of electrical fields and said point coincides with the focus point of the secondary particles.
References Cited (Backward Citations)
US4464571A
Cited
JPS58197644A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-03-01 | 1991-08-31 | 1992-03-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-03-01 | 1995-08-31 | 1996-03-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-03-01 | 1999-08-31 | 2000-03-01 | $7700.00 | Window Closed / Lapsed |