US5444389A
Expired / Lapsed
US
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Method and apparatus for measuring lifetime of minority carriers in semiconductor
Assignee: Dainippon Screen Manufacturing Co Ltd
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Filing: 1993-09-17
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Granted: 1995-08-22
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Expires: 2013-09-17
Abstract
Abstract A capacitor is connected to an insulating film on a semiconductor wafer. A high-frequency voltage with a bias is applied to the series combination of the semiconductor wafer and the capacitor. The bias voltage is changed stepwise, and the change of the total capacitance is measured. The minority carrier lifetime is calculated from the time-dependent change of the total capacitance.
Inventors
- 👤 Sadao Hirae
- 👤 Motohiro Kouno
- 👤 Takamasa Sakai
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 10:07
CPC Classifications
G; G01; G01R; G01R31/00; G01R31/28; G01R31/302; G01R31/312; G01R31/26; G01R31/2648
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
109 words
A method of measuring the minority carrier lifetime in a semiconductor, comprising the steps of: (a) preparing a semiconductor wafer having a substrate and an insulating film formed on said substrate; (b) forming a series combination of said semiconductor wafer and a capacitor; (c) applying a high-frequency voltage with a bias to said series combination of said semiconductor wafer and said capacitor; (d) changing said bias stepwise while measuring a time-dependent change, responsive to said stepwise change of said bias, of a total capacitance of said series combination; and (e) calculating a minority carrier lifetime in said substrate by the analysis of said time-dependent change of said total capacitance.
Claim 2
Independent Claim
109 words
A method of measuring the minority carrier lifetime in a semiconductor, comprising the steps of: (a) preparing a semiconductor wafer having a substrate and an insulating film formed on said substrate; (b) forming a series combination of said semiconductor wafer and a capacitor; (c) applying a high-frequency voltage with a bias to said series combination of said semiconductor wafer and said capacitor; (d) changing said bias stepwise while measuring a time-dependent change, responsive to said stepwise change of said bias, of a total capacitance of said series combination; and (e) calculating a minority carrier lifetime in said substrate by the analysis of said time-dependent change of said total capacitance.
Claim 3
Dependent Claim
29 words
A method in accordance with claim 1, wherein said step (b) comprises the steps of: forming an electrode on said insulating film; and connecting said capacitor with said electrode.
Claim 4
Dependent Claim
63 words
A method in accordance with claim 1, wherein said step (b) comprises the steps of: supporting a test electrode spaced from a surface of said insulating film to form said capacitor between said test electrode and said insulating film; measuring a distance between said test electrode and said insulating film; and calculating a capacitance of said capacitor on the basis of said distance.
Claim 5
Dependent Claim
94 words
A method in accordance with claim 3, wherein said step of measuring said distance comprises the steps of: emitting monochromatic light and directing said light so that said light is incident on a reflecting surface which is located substantially parallel to said surface of said insulating film, said test electrode being associated in fixed relationship with said reflecting surface; reflecting said monochromatic light at said reflecting surface; measuring an intensity of said monochromatic light reflected by said reflecting surface; and measuring said distance on the basis of said intensity of said reflected monochromatic light.
Claim 6
Dependent Claim
54 words
A method in accordance with claim 1, wherein said step (b) comprises the steps of: preparing a test electrode having a dielectric body fixed on said test electrode; and placing said test electrode on said semiconductor wafer such that said dielectric body and said insulating film contact each other to thereby form said capacitor.
Claim 7
Independent Claim
145 words
An apparatus for measuring a minority carrier lifetime in a semiconductor, comprising: a table for receiving a semiconductor wafer, said semiconductor wafer having a substrate and an insulating film formed on a first surface of said substrate, said table having conductive means for contacting a second surface of said substrate; means for forming a series combination of a capacitor and said semiconductor wafer; an electric power supply which is arranged for supplying a high-frequency voltage with a bias to said series combination of said semiconductor wafer and said capacitor connected to said insulating film, and for changing said bias stepwise; measuring means for measuring a time-dependent change of a total capacitance of said series combination in response to said stepwise bias change; and calculating means for calculating a minority carrier lifetime in said substrate on the basis of said time-dependent change of said total capacitance.
Claim 8
Independent Claim
145 words
An apparatus for measuring a minority carrier lifetime in a semiconductor, comprising: a table for receiving a semiconductor wafer, said semiconductor wafer having a substrate and an insulating film formed on a first surface of said substrate, said table having conductive means for contacting a second surface of said substrate; means for forming a series combination of a capacitor and said semiconductor wafer; an electric power supply which is arranged for supplying a high-frequency voltage with a bias to said series combination of said semiconductor wafer and said capacitor connected to said insulating film, and for changing said bias stepwise; measuring means for measuring a time-dependent change of a total capacitance of said series combination in response to said stepwise bias change; and calculating means for calculating a minority carrier lifetime in said substrate on the basis of said time-dependent change of said total capacitance.
Claim 9
Dependent Claim
28 words
An apparatus in accordance with claim 6, wherein said conductive means is a metal portion of said table disposed for contacting said second main surface of said substrate.
Claim 10
Dependent Claim
26 words
An apparatus in accordance with claim 6, further comprising an electrode formed on said insulating film, said electrode being disposed for being connected with said capacitor.
Claim 11
Dependent Claim
71 words
An apparatus in accordance with claim 6, further comprising: electrode supporting means for supporting a test electrode spaced from a surface of said insulating film so as to form said capacitor between said test electrode and said insulating film; distance measuring means for measuring a distance between said test electrode and said insulating film; and capacitance calculating means for calculating a capacitance of said capacitor on the basis of said distance.
Claim 12
Dependent Claim
72 words
An apparatus in accordance with claim 9, wherein said distance measuring means comprises: a light source for emitting monochromatic light; a light reflecting surface located substantially parallel to said surface of said insulating film for reflecting said monochromatic light at said reflecting surface, wherein said test electrode is arranged in fixed relation to said reflecting surface; and a photosensor for measuring an intensity of said monochromatic light reflected by said reflecting surface.
Claim 13
Dependent Claim
18 words
An apparatus in accordance with claim 10, wherein said reflecting surface is comprised in a light transmission reflector.
Claim 14
Dependent Claim
27 words
An apparatus in accordance with claim 11, wherein said photosensor is disposed for measuring said intensity when geometric total optical reflection occurs in said light transmission reflector.
Claim 15
Dependent Claim
17 words
An apparatus in accordance with claim 10, wherein said test electrode is attached to said reflecting surface.
Claim 16
Dependent Claim
60 words
An apparatus in accordance with claim 6, further comprising: electrode supporting means for supporting a test electrode with a dielectric body fixed on said electrode, and for placing said test electrode on said semiconductor wafer such that said dielectric body and said insulating film contact each other to thereby form said capacitor between said test electrode and said insulating film.
References Cited (Backward Citations)
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