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US3919558A Expired / Lapsed US ⏱️ 0.0 years remaining

Hot sub-stage for a scanning electron microscope

Assignee: General Electric Co
•
Filing: 1974-11-04
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Granted: 1975-11-11
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Expires: 1994-11-04
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Abstract

Abstract The present invention relates to a hot sub-stage for a scanning electron microscope characterized by a minimum heated mass, easy outgassing and capable of operation at temperatures in the vicinity of 2500*K. The hot sub-stage employs a boat for holding the sample, formed of a flexible, reflective, refractory conductive foil, through which heating current passes. The sample is enfolded in the boat and disposed so that image forming secondary electrons may pursue both rectilinear and curved paths from the sample through a thermionic electron suppression grid to the secondary electron collection means. This geometry provides excellent discrimination against unwanted thermionic electrons and yet minimizes velocity selection of the more energetic secondary electrons. Heater magnetic field neutralization for avoiding beam offset is also provided.

Inventors

  • 👤 Joseph W Brouillette
  • 👤 William E Leyshon

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-11-07 15:35
CPC Classifications
H; H01; H01J; H01J37/00; H01J37/02; H01J37/20

Claims Analysis

Total Claims: 4
Claim 1
Independent Claim 199 words
A hot sub-stage for supporting and heating a sample in a scanning electron microscope wherein an electron beam impinges on a sample and secondary electrons emitted from the beam impact area are collected for image formation, the collection means having a field for accelerating electrons from said impact region, said hot-stage comprising: a boat for supporting and heating said sample in a position allowing secondary electrons emitted from said impact area to pursue both rectilinear and curved propagation paths to said collection means, said boat being formed of a flexible, reflective, refractory, conductive foil, deformable to enclose said sample in a heat confining manner while avoiding interference with said beam or said propagation paths, said foil having current conducting cross-sections selected for electrically heating said sample, terminal means arranged to provide two point electrical contact for heating and mechanically supporting said boat, and a conductive grid in close proximity to said boat, embracing said propagation paths and oriented in a plane perpendicular thereto, said grid having a potential in respect to said boat which is selected to prevent thermionically emitted electrons from penetrating said grid and entering said collection field while permitting secondary electrons to enter said collection field.
Claim 2
Dependent Claim 199 words
A hot sub-stage for supporting and heating a sample in a scanning electron microscope wherein an electron beam impinges on a sample and secondary electrons emitted from the beam impact area are collected for image formation, the collection means having a field for accelerating electrons from said impact region, said hot-stage comprising: a boat for supporting and heating said sample in a position allowing secondary electrons emitted from said impact area to pursue both rectilinear and curved propagation paths to said collection means, said boat being formed of a flexible, reflective, refractory, conductive foil, deformable to enclose said sample in a heat confining manner while avoiding interference with said beam or said propagation paths, said foil having current conducting cross-sections selected for electrically heating said sample, terminal means arranged to provide two point electrical contact for heating and mechanically supporting said boat, and a conductive grid in close proximity to said boat, embracing said propagation paths and oriented in a plane perpendicular thereto, said grid having a potential in respect to said boat which is selected to prevent thermionically emitted electrons from penetrating said grid and entering said collection field while permitting secondary electrons to enter said collection field.
Claim 3
Dependent Claim 25 words
A hot sub-stage as set forth in claim 1 wherein said grid is of a fine mesh to prevent field penetration by said collection field.
Claim 4
Dependent Claim 48 words
A hot sub-stage as set forth in claim 1 wherein a pair of conductors are provided paralleling said boat and connected to one of said electrical contact points for canceling the electromagnetic fields over said sample resulting from heater current and thereby reducing the amount of beam deflection.

References Cited (Backward Citations)

US3297869A Cited
US3624390A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1978-11-10 1979-05-12 1979-11-11 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1982-11-10 1983-05-12 1983-11-11 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 1986-11-10 1987-05-12 1987-11-11 $7700.00 Window Closed / Lapsed

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