US 4,897,545 A · Electron detector for use in a gaseous environment · patentgrep

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Abstract

An improved gaseous detector device for an environmental scanning electron microscope (ESEM) is provided. The detector device includes a generally annular electrode assembly having an inner electron detector formed of a thin ring, an intermediate electron detector positioned radially outwardly of the inner electron detector which is formed of a first plurality of concentric arc segments, and an outer electron detector positioned radially outwardly of the intermediate electron detector which is formed of a second plurality of concentric arc segments. The first plurality of concentric arc segments is positioned generally normal to the second plurality of concentric arc segments to obtain a directional topographic contrast. The inner, intermediate and outer electron detectors are aligned along generally the same horizontal plane.

Claims50

Dependent claims

An improved environmental scanning electron microscope comprising:

(a) means for generating and directing an electron beam towards a specimen;
(b) means for detecting signals emanating from the surface of the specimen;
said detecting means including a generally annular electrode assembly having an inner electron detector formed of a thin ring, an intermediate electron detector positioned radially outwardly of said inner electron detector and being formed of a first plurality of concentric arc segments, and an outer electron detector positioned radially outwardly of said intermediate electron detector and being formed of a second plurality of concentric arc segments, said first plurality of concentric arc segments being positioned generally normal to said second plurality of concentric arc segments to obtain a directional topography contrast, said inner, intermediate, and outer electron detectors being aligned along generally the same horizontal plane;
and
(c) means for separately biasing said inner, intermediate and outer electron detector initially at the same electrical potential.

2 more elements

An improved environmental scanning electron microscope comprising:

(a) a vacuum column having a pressure limiting aperture at the lower end thereof;
(b) a charged particle beam source located within the vacuum column which emits a charged particle beam;
(c) focusing means located within the vacuum column which directs a charged particle beam emitted by said charged particle beam source through said pressure limiting aperture;
(d) a specimen chamber, positioned below said pressure limiting aperture, which maintains the specimen enveloped in gas at a pressure of approximately 1 to 25 Torr in registration with the pressure limiting aperture such that a surface of the sample may be exposed to a charged particle beam emitted from the charged particle beam source and directed through said pressure limiting aperture;
(e) a specimen mount located within said specimen chamber and positioned for supporting said specimen approximately 1 mm below said pressure limiting aperture so as to allow the focused beam of electrons to interact with said specimen;
(f) first means for detecting signals emanating from the surface of the specimen;
said first detecting means including a generally annular electrode assembly having an inner electron detector formed of a thin ring, and intermediate electron detector positioned radially outwardly of said inner electron detector and being formed of a first plurality of concentric are segments, and an outer electron detector positioned radially outwardly of said intermediate electron detector and being formed of a second plurality of concentric arc segments;
said first plurality of concentric arc segments being positioned generally normal to said second plurality of concentric arc segments;
said inner, intermediate, and outer electron detectors being aligned along generally the same horizontal plane;
and
(g) means for separately biasing said inner, intermediate and outer electron detectors initially at the same electrical potential.

8 more elements

An improved environmental scanning electron microscope comprising:

(a) a substantially cylindrical objective lens magnetic housing containing an axially disposed vacuum liner tube having a pressure limiting aperture and containing means for magnetically focusing the beam of electrons passing through said liner tube toward a specimen;
(b) a specimen chamber positioned below said objective lens, said specimen chamber maintaining the specimen enveloped in gas in registration with the pressure limiting aperture such that a surface of the specimen may be exposed to the focused beam of electrons;
(c) means for detecting signals emanating from the surface of the specimen, said detection means including:
(1) a first electron detection formed integrally with said pressure limiting aperture;
(2) a second electron detection positioned below said pressure limiting aperture formed of a thin ring;
(3) third and fourth electron detectors positioned radially outwardly of said second electron detector and each formed as a plurality of concentric arc segments;
and
(4) a fifth electron detector positioned above said pressure limiting aperture.

5 more elements

An improved environmental scanning electron microscope comprising:

(a) a vacuum column having a pressure limiting aperture at the lower end thereof;
(b) a charged particle beam source located within the vacuum column which emits a charged particle beam through said pressure limiting aperture;
(c) focusing means located within said vacuum column which directs a charged particle beam emitted by said charged particle beam source through said pressure limiting aperture;
(d) a specimen chamber, positioned below said pressure limiting pressure which maintains the specimen, enveloped in gas, at a pressure of approximately 1 to 25 Torr in registration with said pressure limiting aperture such that a surface of the sample way be exposed to a charged particle beam emitted from said charged particle beam source and directed through said pressure limiting aperture;
(e) a specimen mount located within said specimen chamber and positioned for supporting said specimen approximately 1 to 20 mm below said pressure limiting aperture so as to allow the focused beam of electrons to interact with said specimen;
(f) an electron detector means including a generally annular electrode assembly having an inner electron detector formed of a thin ring and an outer electron detector which is formed of a plurality of concentric arc segments and a pressure limiting aperture detector formed integrally with said pressure limiting aperture;
(g) a control grid being biased at an electrical potential which is between the bias applied to said specimen mount and said electron detector means so as to accelerate the signals emitted from the specimen towards said control grid for further amplification of secondary electrons.

4 more elements

An improved environmental scanning electron microscope comprising:

(a) a vacuum column having a pressure limiting aperture at the lower end thereof;
(b) a charged particle beam source located within the vacuum column which emits a charged particle beam;
(c) focusing means located within the vacuum column which directs a charged particle beam emitted by said charged particle beam source through said pressure limiting aperture;
(d) a specimen chamber, positioned below said pressure limiting aperture, which maintains the specimen, enveloped in gas, at a pressure of approximately 1 to 25 Torr in registration with the pressure limiting aperture such that a surface of the sample may be exposed to a charged particle beam emitted from the charged particle source and directed through said pressure limiting aperture;
(e) a specimen mount located within said specimen chamber and positioned for supporting said specimen below said pressure limiting aperture so as to allow the focused beam of electrons to interact with said specimen;
(f) a generally annular electrode assembly having an inner electrode detector formed of a thin ring, an intermediate electron detector positioned radially outwardly of said inner electron detector and being formed of a first plurality of concentric arc segments, and an outer electron detector positioned radially outwardly of said intermediate electron detector and being formed of a second plurality of concentric arc segments;
and
(e) a control grid positioned between said specimen mount and said generally annular electrode assembly within said specimen chamber, said control grid being biased at an electrical potential greater than the bias applied to the specimen mount and less than the bias applied to said generally annular electrode assembly such that the electrons are accelerated from the specimen to said control grid to produce increased amplification.

5 more elements

Dependencies are inferred from the claim text.

Facts

Application: 07/257,754Filed 14 Oct 1988 · continuation in part
Priority: AU PI491816 Oct 1987
Granted: 30 Jan 1990
Term ends: Not estimatedThe source records don’t support an estimate.

Classification9 codes

H01J 37/28
Electron or ion microscopes; Electron or ion diffraction tubes: with scanning beams
H01J 37/244
Details: detectors; Associated components or circuits therefor
H01J 2237/24465
Position sensitive detectors: sectored detectors, e.g. quadrants
H01J 2237/24475
Detection characterized by the detecting means: scattered electron detectors

Family

Serial52,700Parent of this continuation-in-part · filed 21 May 1987
Serial158,208Parent of this continuation-in-part · filed 19 Feb 1988
US 4,785,182 AParent of this continuation-in-part
US 4,823,006 AParent of this continuation-in-part
US 4,897,545 AThis patent

From the US filing history. Foreign family members aren’t listed.

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