AU7802387A - Scanning electron microscope - Google Patents
Scanning electron microscopeInfo
- Publication number
- AU7802387A AU7802387A AU78023/87A AU7802387A AU7802387A AU 7802387 A AU7802387 A AU 7802387A AU 78023/87 A AU78023/87 A AU 78023/87A AU 7802387 A AU7802387 A AU 7802387A AU 7802387 A AU7802387 A AU 7802387A
- Authority
- AU
- Australia
- Prior art keywords
- sample
- electron beam
- emitted
- meters
- photons
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
- H01J37/26—Electron or ion microscopes; Electron or ion diffraction tubes
- H01J37/28—Electron or ion microscopes; Electron or ion diffraction tubes with scanning beams
Description
MULTIPURPOSE GASEOUS DETECTOR DEVICE FOR ELECTRON MICROSCOPES
Background of the Invention
Scanning electron microscopes and generally instruments employing an electron beam (probe) operate in vacuum (pressure less than about 0.0001 mbar) and the specimens examined by such instruments are also placed in vacuum. Scanning a sample within a vacuum presents many problems. Many biological specimens cannot survive in vacuum. Wet specimens can experience evaporation of their fluid content before an accurate image can be obtained. Nonconducting samples can accumulate a surface charge which obscures the details of the sample's surface and lowers the resolution of the image obtained.
An environmental scanning electron microscope (ESEM) which allows the examination of specimens in a gaseous environment is described in U.S. Patent No. 4,596,928. However, the predominant detection mode in the ESEM has utilized various scintillator detectors to detect backscattered electrons. Additionally, an ESEM detection system has been described wherein the
ionization of the gaseous environment is used as the detection means for all ionizing signals (Danilatos, Micron. Microsc. Acta 14:307-318, 1983).
On object of the present invention is to provide a more general and multiputpose means for environmental scanning electron microscopy.
Summary of the Invention
The present invention provides a scanning electron microscope for cathodoluminescenct detection of specimens which comprises a vacuum envelope having a pressure limiting aperture. An electron beam source is located within the vacuum envelope and is capable of emitting an electron beam. Pocusing means are located within the vacuum envelope and are capable of directing an electron beam emitted by the electron beam source through the pressure limiting aperture. Electron beam scanning means are also located within the vacuum envelope and are capable of scanning an electron beam emitted by the electron beam source across the diameter of the pressure limiting aperture. A sample platform means is disposed outside the vacuum envelope and is capable of maintaining a sample in registration with the pressure limiting aperture such that a surface of the sample may be exposed to an electron beam emitted from the electron beam source and directed through the pressure limiting aperture so as to cause radiation to be emitted from the sample. The scanning electron microscope of the present invention further comprises gas containment means capable of maintaining the sample platform means enveloped in a gaseous medium so as to
allow radiation emitted from a sample located on the sample platform means and exposed to an electron beam emitted from the electron beam source to come into contact with gas molecules of the gaseous medium and cause the gas molecules to emit photons. Detection means are provided which are capable of detecting photons emitted from the gas molecules of the gaseous medium.
The present invention also provides a method for microscopically imaging the surface of a sample which comprises surrounding the sample with gas molecules and scanning the surface of the sample with an electron beam having sufficient energy so as to cause radiation to be emitted from the surface of the sample. Photons which are emitted from the gas molecules which come into contact with radiation emitted from the surface of the sample are then detected, the photons being emitted from the gas molecules in an amount proportional to the amount of radiation emitted from the surface of the sample. Images of the sample are then formed based on the number of photons detected.
Brief Description of the Figure
Fig. 1 is a schematic cross-sectional view of a device which embodies the present invention in a particular form.
Detailed Description of the Invention
The present invention provides a scanning electron microscope. Referring in more particularity to Figure
1, the invention comprises a vacuum envelope 1 having a pressure limiting aperture 2. An electron beam source 3 is located within the vacuum envelope and is capable of emitting an electron beam. Focusing means 4 are located within the vacuum envelope and are capable of directing an electron beam emitted by the electron beam source through the pressure limiting aperture. Electron beam scanning means 5 are also located within the vacuum envelope and are capable of scanning an electron beam emitted by the electron beam source across the diameter of the pressure limiting aperture. A sample platform means 6 is disposed outside the vacuum envelope and is capable of maintaining a sample in registration with the pressure limiting aperture such that a surface of the sample may be exposed to an electron beam emitted from the electron beam source and directed through the pressure limiting aperture so as to cause radiation to be emitted from the sample. Within this application, "radiation" emitted from a sample means electrons or photons emitted from the sample.
The scanning electron microscope of the present invention further comprises a gas containment means 7 capable of maintaining the sample platform means enveloped in a gaseous medium so as to allow radiation emitted from a sample located on the sample platform means and exposed to an electron beam emitted from the electron beam source to come into contact with gas molecules, of the gaseous medium and cause the gas molecules to emit photons. Detection means 8 are provided which are capable of detecting photons emitted from the gas molecules of the gaseous medium.
In one embodiment of the invention, the wavelength of the photons is within the range from about 1x10-11 meters to about 4x10-8 meters. Preferably within this embodiment of the invention the detection means is a scintillation counter or a lithium drifted silicon detector.
In another embodiment of the invention, the wavelength of the photons is within the range from about 4x10-8 meters to about 7x10-7 meters. Preferably within this embodiment of the invention the detection means is a photomultiplier tube or a photodiode.
In yet another embodiment of the invention, tne wavelength of the photons is within the range from about 7x10-7 meters to aoout 2x10-4 meters. Preferably within this embodiment of the invention the detection means is a photomultiplier tube or a photodiode.
The gaseous medium may comprise a single gas or a mixture of gases. In one embodiment of the invention the gaseous medium comprises nitrogen. In another embodiment of the invention the gaseous medium comprises helium.
The present invention also provides a method for microscopically imaging the surface of a sample which comprises surrounding the sample with gas molecules and scanning the surface of the sample with an electron beam having sufficient energy so as to cause radiation to be emitted from the surface of the sample. Photons which are emitted from gas molecules which come into contact with radiation emitted from the surface of the sample are then detected, the photons being emitted from the gas in an amount proportional to tne amount of radiation emitted from the surface of the sample. Images of the sample are then formed based on the number of photons detected.
In one emoodiment of the invention, the wavelength of the photons is within the range from aoout 1x10-11 meters to about 4x10-8 meters. Preferably within this embodiment of the invention the detection means is a scintillation counter or a lithium drifted silicon detector.
In another embodiment of the invention, the wavelength of the photons is within the range from about 4x10-8 meters to about 7x10-7 meters. Preferably within this embodiment of the invention the detection means is a photomultiplier tube or a photodiode.
In yet a further embodiment of the invention, the wavelength of the photons is within the range from aoouc 7x10-7 meters to about 2x10-4 meters. Preferably within this embodiment of the invention the detection means is a photomultiplier tube or a photodiode.
The gaseous medium may comprise a single gas or a mixture of gases. In one emoodiment of the invention, the gaseous medium comprises nitrogen. In yet another embodiment of the invention, the gaseous medium comprises helium.
Claims (22)
1. A scanning electron microscope which comprises:
a) a vacuum envelope having a pressure limiting aperture;
b) an electron beam source located within the vacuum envelope and capable of emitting an electron beam;
c) focusing means located within the vacuum envelope and capable of directing an electron beam emitted by the electron beam source through the pressure limiting aperture;
d) electron beam scanning means located within the vacuum envelope and capable of scanning an electron beam emitted by the electron beam source across the diameter of the pressure limiting aperture;
e) sample platform means, disposed outside the vacuum envelope, capable of maintaining a sample in registration with the pressure lim iting aperture such that a surface of the sample may be exposed to an electron beam emitted from the electron beam source and directed through the pressure limiting aperture so as to cause radiation to be emitted from the sample;
f) gas containment means capable of maintaining the sample platform means enveloped in a gaseous medium so as to allow radiation emitted from a sample located on the sample platform means and exposed to an electron beam emitted from the electron beam source to come into contact with gas molecules of the gaseous medium and cause the gas molecules to emit photons; and
g) detection means capable of detecting photons emitted from the gas molecules of the gaseous medium.
2. A device of claim 1 wherein the wavelength of the photons is within the range from about 1 x 10-11 meters to about 4 x 10-8 meters.
3. A device of claim 2 wherein the detection means is a scintillation counter.
4. A device of claim 2 wherein the detection means is a lithium drifted silicon detector.
5. A device of in claim 1 wherein the wavelength of the photons is within the range from about 4 x
10-8 meters to about 7 x 10-7 meters.
6. A device of claim 5 wherein the detection means is a photomultiplier tube.
7. A device of claim 5 wherein the detection means is a photodiode.
8. A device of claim 1 wherein the wavelength of the photons is within the range from about 7 x 10-7 meters to about 2 x 10-4 meters.
9. A device of claim 8 wherein the detection means is a photomultiplier tube.
10. A device of claim 8 wherein the detection means is a photodiode.
11. A device of claim 1 wherein the gaseous medium comprises a single gas.
12. A device of claim 1 wherein the gaseous medium comprises a mixture of gases.
13. A device of claim 1 wherein the gaseous medium comprises nitrogen.
14. A device of claim 1 wherein the gaseous medium comprises helium.
15. A method for microscopically imaging the surface of a sample which comprises:
a) surrounding the sample with gas molecules;
b) scanning the surface of the sample with an electron beam having sufficient energy so as to cause radiation to be emitted from the surface of the sample;
c) detecting photons emitted from gas molecules which come into contact with radiation emitted from the surface of the sample, the photons being emitted from the gas molecules in an amount proportional to the amount of radiation emitted from the surface of the sample; and
d) forming images of the sample based on the number of photons detected.
16. A method of claim 15 wherein the wavelength of the photons is within the range from about 1 x 10-11 meters to about 4 x 10-8 raeters.
17. A method of claim 15 wherein the wavelength of the photons is within the range from about 4 x 10-8 meters to about 7 x 10-7 meters.
18. A method of claim 15 wherein the wavelength of the photons is within the range from about 7 x 10-7 meters to about 2 x 10-4 meters.
19. A method of claim 15 wherein the gaseous medium comprises a single gas.
20. A method of claim 15 wherein the gaseous medium comprises a mixture of gases.
21. A method of claim 15 wherein the gaseous medium comprises. nitrogen.
22. A method of claim 15 wherein the gaseous medium comprises. helium.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AU78023/87A AU597715B2 (en) | 1986-08-01 | 1987-07-30 | Scanning electron microscope |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AUPH722186 | 1986-08-01 | ||
| AUPH7221 | 1986-08-01 | ||
| AU78023/87A AU597715B2 (en) | 1986-08-01 | 1987-07-30 | Scanning electron microscope |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| AU7802387A true AU7802387A (en) | 1988-02-24 |
| AU597715B2 AU597715B2 (en) | 1990-06-07 |
Family
ID=25638803
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| AU78023/87A Ceased AU597715B2 (en) | 1986-08-01 | 1987-07-30 | Scanning electron microscope |
Country Status (1)
| Country | Link |
|---|---|
| AU (1) | AU597715B2 (en) |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3612859A (en) * | 1968-01-31 | 1971-10-12 | Westinghouse Electric Corp | Method for measuring and controlling the density of a metallic vapor |
| AU534811B2 (en) * | 1979-07-03 | 1984-02-16 | Unisearch Limited | Atmospheric scanning electron microscope |
-
1987
- 1987-07-30 AU AU78023/87A patent/AU597715B2/en not_active Ceased
Also Published As
| Publication number | Publication date |
|---|---|
| AU597715B2 (en) | 1990-06-07 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PC | Assignment registered |
Owner name: FEI COMPANY Free format text: FORMER OWNER WAS: PHILIPS ELECTRONICS NORTH AMERICA CORPORATION |
|
| MK14 | Patent ceased section 143(a) (annual fees not paid) or expired |