US5138256A
Expired / Lapsed
US
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Method and apparatus for determining the thickness of an interfacial polysilicon/silicon oxide film
Assignee: International Business Machines Corp
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Filing: 1991-04-23
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Granted: 1992-08-11
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Expires: 2011-04-23
Abstract
Abstract A method and apparatus for determining the thickness of an interfacial oxide film intermediate to a polysilicon layer of a first conductivity type and a silicon substrate of a second conductivity type supporting a p-n junction. Radiant energy, preferably in the form of light, is directed on to the top surface of the polysilicon layer thereby stimulating carriers which concentrate at the interfacial oxide film, allowing the excited carriers to diffuse across the oxide film, and creating a short circuit, the magnitude of which is inversely related to the thickness of the interfacial oxide film.
Inventors
- 👤 Richard J. Murphy
- 👤 Jerome D. Schick
- 👤 Howard R. Wilson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 10:44
CPC Classifications
G; G01; G01B; G01B7/00; G01B7/02; G01B7/06; G01B7/08; G01B15/00; G01B15/02; G01R; G01R31/00; G01R31/28; G01R31/302; G01R31/305
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
109 words
A method for determining the thickness of an interfacial film intermediate to a silicon region and a layer of polysilicon, said silicon region including a first layer of a first conductivity type over a second layer of a second conductivity type proximate to said interfacial film, said method comprising the steps of: stimulating carriers in the polysilicon layer to excite said carriers to diffuse across said interfacial film, so as to generate a short circuit current across said interfacial film; and measuring said short circuit current and determining said film thickness therefrom, the magnitude of said short circuit current being inversely proportional to the thickness of said interfacial film.
Claim 2
Independent Claim
109 words
A method for determining the thickness of an interfacial film intermediate to a silicon region and a layer of polysilicon, said silicon region including a first layer of a first conductivity type over a second layer of a second conductivity type proximate to said interfacial film, said method comprising the steps of: stimulating carriers in the polysilicon layer to excite said carriers to diffuse across said interfacial film, so as to generate a short circuit current across said interfacial film; and measuring said short circuit current and determining said film thickness therefrom, the magnitude of said short circuit current being inversely proportional to the thickness of said interfacial film.
Claim 3
Dependent Claim
33 words
A method as in claim 1, wherein said polysilicon layer is n-type and said silicon region is predominantly p-type and wherein said silicon region supports a p-n junction proximate to said interfacial film.
Claim 4
Dependent Claim
26 words
A method as in claim 2, wherein said interfacial film is an oxide film, and includes contaminant elements which affect the operation of said p-n junction.
Claim 5
Dependent Claim
18 words
A method as in claim 2, whereby said p-n junction is the base/emitter junction of an NPN transistor.
Claim 6
Dependent Claim
22 words
A method as in claim 1, wherein said stimulating step includes impinging radiant energy into said polysilicon layer above said interfacial film.
Claim 7
Dependent Claim
33 words
A method as in claim 1, wherein said polysilicon layer is p-type and said silicon region is predominantly n-type and wherein said silicon region supports a p-n junction proximate to said interfacial film.
Claim 8
Dependent Claim
20 words
A method as in claim 1, wherein said silicon region comprises an epitaxial layer formed on an underlying silicon substrate.
Claim 9
Independent Claim
125 words
An apparatus for determining the thickness of an interfacial film intermediate to a silicon region and to a layer of polysilicon, said silicon region of a first conductivity type, said polysilicon of a second conductivity type, said silicon region supporting a first layer of a first conductivity type over a second layer of a second conductivity type proximate to said film, said apparatus comprising: means for stimulating carriers in the polysilicon layer to excite said carriers to diffuse across said interfacial film, so as to generate a short circuit current across said interfacial film; and means for measuring said short circuit current and determining said film thickness therefrom, the magnitude of said short circuit current being inversely proportional to the thickness of said interfacial film.
Claim 10
Independent Claim
125 words
An apparatus for determining the thickness of an interfacial film intermediate to a silicon region and to a layer of polysilicon, said silicon region of a first conductivity type, said polysilicon of a second conductivity type, said silicon region supporting a first layer of a first conductivity type over a second layer of a second conductivity type proximate to said film, said apparatus comprising: means for stimulating carriers in the polysilicon layer to excite said carriers to diffuse across said interfacial film, so as to generate a short circuit current across said interfacial film; and means for measuring said short circuit current and determining said film thickness therefrom, the magnitude of said short circuit current being inversely proportional to the thickness of said interfacial film.
Claim 11
Dependent Claim
33 words
An apparatus as in claim 8, wherein said polysilicon layer is p-type and said silicon region is predominantly n-type and wherein said silicon region supports a p-n junction proximate to said interfacial film.
Claim 12
Dependent Claim
17 words
An apparatus as in claim 9, wherein said p-n junction is the base/emitter junction of a transistor.
Claim 13
Dependent Claim
26 words
An apparatus as in claim 8, wherein said means for stimulating carriers includes means for directing radiant energy into said polysilicon layer above said interfacial film.
Claim 14
Dependent Claim
16 words
An apparatus as in claim 11, wherein said radiant energy is provided by a light source.
Claim 15
Dependent Claim
33 words
An apparatus as in claim 8, wherein said polysilicon layer is p-type and said silicon region is predominantly n-type and wherein said silicon region supports an n-p junction proximate to said interfacial layer.
Claim 16
Dependent Claim
26 words
An apparatus as in claim 8, wherein said interfacial film is an oxide film and includes contaminant elements which affect the operation of said p-n junction.
Claim 17
Dependent Claim
20 words
An apparatus as in claim 8, wherein said silicon region comprises an epitaxial layer formed on an underlying silicon substrate.
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| 3.5 Years (Year 4) | 1995-08-11 | 1996-02-10 | 1996-08-11 | $2000.00 | Window Closed / Lapsed |
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