US4567431A
Expired / Lapsed
US
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Method for revealing semiconductor surface damage using surface photovoltage (SPV) measurements
Assignee: Intersil Corp
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Filing: 1983-10-31
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Granted: 1986-01-28
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Expires: 2003-10-31
Abstract
Abstract The presence of crystallographic damage in a semiconductor surface region is determined by surface photovoltage (SPV) measurements. Deviations from the idealized straight line SPV plot of photon flux (Io) versus reciprocal absorption coefficient ( alpha -1) in upward-facing concave form are used as a criterion of surface quality. This criterion is used to determine the minimum etching required to remove the damaged surface.
Inventors
- 👤 Alvin M. Goodman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 21:06
CPC Classifications
H; H02; H02S; H02S50/00; H02S50/10; Y; Y02; Y02E; Y02E10/00; Y02E10/50
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
115 words
A method for revealing the presence of damage in the bulk surface region of a body of semiconductor crystalline material comprising the steps of: (a) preparing a layer of the surface region to develop a stable inversion layer at the body surface; (b) measuring the photon flux (I o ) as a function of the optical wavelength (λ) at a constant surface photovoltage to provide a plurality of data points forming a plot of photon flux (I o ) versus reciprocal optical absorption coefficient (α -1 ); and (c) determining the existence of curvature from said plot of said data points as an indicator of crystallographic damage in the material of said bulk surface region.
Claim 2
Independent Claim
115 words
A method for revealing the presence of damage in the bulk surface region of a body of semiconductor crystalline material comprising the steps of: (a) preparing a layer of the surface region to develop a stable inversion layer at the body surface; (b) measuring the photon flux (I o ) as a function of the optical wavelength (λ) at a constant surface photovoltage to provide a plurality of data points forming a plot of photon flux (I o ) versus reciprocal optical absorption coefficient (α -1 ); and (c) determining the existence of curvature from said plot of said data points as an indicator of crystallographic damage in the material of said bulk surface region.
Claim 3
Dependent Claim
59 words
A method according to claim 1 further comprising the step of comparing said plot of data points to a straight line best fitting said data points to determine a correlation coefficient (r) or the square (r 2 ) of said correlations coefficient for said fitted straight line, whereby the value of said coefficient is a measure of said curvature.
Claim 4
Dependent Claim
71 words
The method of claim 2 further comprising the step of determining the standard deviation (σ) from an average value of said coefficient determined from a plurality of said plots according to step (b) of claim 1 for a plurality of bulk surface regions on the same body or different bodies and comparing said coefficient to a coefficient derived from similar data from specimen bodies having known damage or absence of damage.
Claim 5
Dependent Claim
13 words
The method of claim 1 wherein said body is a wafer of silicon.
Claim 6
Dependent Claim
13 words
The method of claim 1 wherein said body is a wafer of germanium.
Claim 7
Dependent Claim
14 words
The method of claim 1 wherein said body is a wafer of gallium arsenide.
Claim 8
Dependent Claim
14 words
The method of claim 2 wherein said coefficient has a value less than 1.
Claim 9
Dependent Claim
36 words
The method of claim 1 wherein said body is formed of n-type silicon material and said preparation step comprises: applying an oxidizing agent taken from the group consisting of potassium dichromate, ammonium dichromate, and potassium permanganate.
Claim 10
Dependent Claim
28 words
The method of claim 1 wherein said body is formed of p-type silicon material and said preparation step comprises removing by etching any oxides existing on said surface.
Claim 11
Dependent Claim
57 words
The method of claim 1 further comprising the steps of: (a) removing a layer of material from said body approximating the estimated depth of damaged material; (b) repeating steps (a), (b), and (c) of claim 1 to determine the presence of damage; and (c) repeating step (a) above as necessary until the damaged surface region is removed.
References Cited (Backward Citations)
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-01-27 | 1989-07-29 | 1990-01-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-01-27 | 1993-07-29 | 1994-01-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-01-27 | 1997-07-29 | 1998-01-28 | $7700.00 | Window Closed / Lapsed |