US5122222A
Expired / Lapsed
US
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Frequency-domain analysis of RHEED data
Assignee: Massachusetts Institute of Technology
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Filing: 1990-09-14
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Granted: 1992-06-16
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Expires: 2010-09-14
Abstract
Abstract Computerized acquisition and frequency-domain analysis of dynamic reflection high-energy electron diffraction (RHEED) intensity data is obtained during growth by molecular-beam epitaxy (MBE). Rapid, accurate determination of the frequency of RHEED oscillations can be obtained not only when these oscillations are well resolved, but also when the growth conditions yield oscillations that are too poorly resolved to permit frequency analysis by conventional procedures. The method has been used to study transients in the growth of AlGaAs on GaAs substrates and also to investigate the hetero-epitaxial growth of GaAs on Si.
Inventors
- 👤 George W. Turner
- 👤 Bettina A. Nechay
- 👤 Stephen J. Eglash
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 23:56
CPC Classifications
G; G01; G01B; G01B11/00; G01B11/02; G01B11/06; G01B11/0616; C; C30; C30B; C30B23/00; C30B23/02; C30B29/00; C30B29/10; C30B29/40; Y; Y10; Y10T; Y10T117/00; Y10T117/10; Y10T117/1004; Y10T117/1008
Claims Analysis
Total Claims: 29
Claim 1
Independent Claim
68 words
A method of controlling the growth of a layer of material as it is being grown, comprising the steps of: (a) subjecting the growing layer to a beam of energy; b) collecting time varying data of the oscillatory variations induced in said beam during the growth process; c) converting said time varying data to frequency varying data; d) utilizing said frequency varying data to control said growth process.
Claim 2
Independent Claim
68 words
A method of controlling the growth of a layer of material as it is being grown, comprising the steps of: (a) subjecting the growing layer to a beam of energy; b) collecting time varying data of the oscillatory variations induced in said beam during the growth process; c) converting said time varying data to frequency varying data; d) utilizing said frequency varying data to control said growth process.
Claim 3
Independent Claim
61 words
A method of analyzing the growth of a layer of material as it is being grown, comprising the steps of: a) directing a beam of energy onto the growing layer; b) generating a time varying beam pattern of the variations in the beam induced by said growth; c) generating a frequency varying beam pattern corresponding to said time varying beam pattern.
Claim 4
Independent Claim
61 words
A method of analyzing the growth of a layer of material as it is being grown, comprising the steps of: a) directing a beam of energy onto the growing layer; b) generating a time varying beam pattern of the variations in the beam induced by said growth; c) generating a frequency varying beam pattern corresponding to said time varying beam pattern.
Claim 5
Dependent Claim
21 words
The method of claim 1 wherein the beam of energy is taken from the group comprising electron, photon or X-ray energy.
Claim 6
Dependent Claim
23 words
The method of claim 1 wherein the collected data relates to data from the group comprising scattered, diffracted, reflected or transmitted beam variations.
Claim 7
Dependent Claim
35 words
The method of claim 1 wherein the collected data is sampled and processed to determine the mean of the data and baseline corrected to compensate for signal drift and filtered to remove undesirable noise components.
Claim 8
Dependent Claim
40 words
The method of claim 5 wherein the data processed in claim 5 is converted by squaring the Fourier transform of the data as normalized by the number of data points sampled and the centroid of the resultant data curve determined.
Claim 9
Dependent Claim
19 words
The method of claim 1 wherein the data comprises only one cycle of oscillation corresponding to one growth layer.
Claim 10
Dependent Claim
21 words
The method of claim 2 wherein the beam of energy is taken from the group comprising electron, photon or X-ray energy.
Claim 11
Dependent Claim
23 words
The method of claim 2 wherein the collected data relates to data from the group comprising scattered, diffracted, reflected or transmitted beam variations.
Claim 12
Dependent Claim
35 words
The method of claim 2 wherein the collected data is sampled and processed to determine the mean of the data and baseline corrected to compensate for signal drift and filtered to remove undesirable noise components.
Claim 13
Dependent Claim
40 words
The method of claim 10 wherein the data processed in claim 5 is converted by squaring the Fourier transform of the data as normalized by the number of data points sampled and the centroid of the resultant data curve determined.
Claim 14
Dependent Claim
19 words
The method of claim 2 wherein the data comprises only one cycle of oscillation corresponding to one growth layer.
Claim 15
Dependent Claim
67 words
Apparatus for controlling the growth of a layer of material during the growth process, comprising: a) an energy source for subjecting the growing layer to a beam of energy; b) apparatus for detecting variations in said energy beam caused by the growth process and generating a time-varying pattern in response thereto; c) apparatus for processing said time varying pattern to produce a frequency varying pattern corresponding thereto.
Claim 16
Dependent Claim
67 words
Apparatus for controlling the growth of a layer of material during the growth process, comprising: a) an energy source for subjecting the growing layer to a beam of energy; b) apparatus for detecting variations in said energy beam caused by the growth process and generating a time-varying pattern in response thereto; c) apparatus for processing said time varying pattern to produce a frequency varying pattern corresponding thereto.
Claim 17
Dependent Claim
61 words
Apparatus for analyzing the growth of a layer of material during growth, comprising: b) apparatus for directing a beam of energy at the growth layer; b) apparatus for generating a time varying beam pattern of the variations in the beam induced by said growth; and c) apparatus for generating a frequency varying beam pattern corresponding to said time varying beam pattern.
Claim 18
Dependent Claim
61 words
Apparatus for analyzing the growth of a layer of material during growth, comprising: b) apparatus for directing a beam of energy at the growth layer; b) apparatus for generating a time varying beam pattern of the variations in the beam induced by said growth; and c) apparatus for generating a frequency varying beam pattern corresponding to said time varying beam pattern.
Claim 19
Independent Claim
85 words
A method of controlling the growth of a layer of semiconductor material as it is being grown, comprising the steps of: a) subjecting the growing layer to a beam of electron energy to obtain a diffraction pattern; b) detecting time varying data of intensity oscillatory variations induced in said beam of the diffraction pattern during the growth process; converting said time varying data to frequency varying data corresponding to said time varying data; and d) utilizing said frequency varying data to control said growth process.
Claim 20
Independent Claim
85 words
A method of controlling the growth of a layer of semiconductor material as it is being grown, comprising the steps of: a) subjecting the growing layer to a beam of electron energy to obtain a diffraction pattern; b) detecting time varying data of intensity oscillatory variations induced in said beam of the diffraction pattern during the growth process; converting said time varying data to frequency varying data corresponding to said time varying data; and d) utilizing said frequency varying data to control said growth process.
Claim 21
Independent Claim
67 words
A method of analyzing the growth of a layer of semiconductor material as it is being grown, comprising the steps of: a) directing a beam of electron energy onto the growing semiconductor layer; b) detecting a time varying diffraction beam pattern of the variations in the electron beam induced by said growth; and c) generating a frequency varying beam pattern corresponding to said time varying beam pattern.
Claim 22
Independent Claim
67 words
A method of analyzing the growth of a layer of semiconductor material as it is being grown, comprising the steps of: a) directing a beam of electron energy onto the growing semiconductor layer; b) detecting a time varying diffraction beam pattern of the variations in the electron beam induced by said growth; and c) generating a frequency varying beam pattern corresponding to said time varying beam pattern.
Claim 23
Dependent Claim
75 words
Apparatus for controlling the growth of a layer of semiconductor material during the growth process, comprising: a) an energy source for subjecting the growing layer to a beam of electron energy to produce a diffraction pattern; b) apparatus for detecting variations in said electron energy beam caused by the growth process and generating a time-varying pattern in response thereto; c) apparatus for processing said time varying pattern to produce a frequency varying pattern corresponding thereto.
Claim 24
Dependent Claim
75 words
Apparatus for controlling the growth of a layer of semiconductor material during the growth process, comprising: a) an energy source for subjecting the growing layer to a beam of electron energy to produce a diffraction pattern; b) apparatus for detecting variations in said electron energy beam caused by the growth process and generating a time-varying pattern in response thereto; c) apparatus for processing said time varying pattern to produce a frequency varying pattern corresponding thereto.
Claim 25
Independent Claim
144 words
A method of analyzing the growth of a layer of semiconductor material as it is being grown, comprising the steps of: a) subjecting the growing layer to a beam of electron energy to obtain a diffraction pattern; b) detecting time varying data of intensity oscillatory variations induced in said beam of the diffraction pattern during the growth process; c) converting said time varying data to frequency varying data corresponding to said time varying data by (i) determining the mean of the varying data; (ii) determining the baseline trend of the mean of the time varying data by fitting a polynomial to the data and subtracting the baseline from the data; (iii) processing the baseline time varying data by taking a Fourier transform of the baseline time varying data to generate said frequency varying data; and (iv) determining the centroid of such frequency varying data.
Claim 26
Independent Claim
144 words
A method of analyzing the growth of a layer of semiconductor material as it is being grown, comprising the steps of: a) subjecting the growing layer to a beam of electron energy to obtain a diffraction pattern; b) detecting time varying data of intensity oscillatory variations induced in said beam of the diffraction pattern during the growth process; c) converting said time varying data to frequency varying data corresponding to said time varying data by (i) determining the mean of the varying data; (ii) determining the baseline trend of the mean of the time varying data by fitting a polynomial to the data and subtracting the baseline from the data; (iii) processing the baseline time varying data by taking a Fourier transform of the baseline time varying data to generate said frequency varying data; and (iv) determining the centroid of such frequency varying data.
Claim 27
Dependent Claim
161 words
Apparatus for controlling the growth of a layer of semiconductor material during the growth process, comprising: a) an energy source for subjecting the growing layer to a beam of electron energy to produce a diffraction pattern; b) apparatus for detecting variations in said electron energy beam caused by the growth process and generating a time-varying digitized voltage pattern in response thereto; c) apparatus for processing said time varying pattern to produce a frequency varying pattern corresponding thereto comprising: (i) apparatus for determining the mean of the time varying data; (ii) apparatus for determining the baseline trend of the time varying data by fitting a polynomial to the data and subtracting the baseline from the mean of the data; and (iii) apparatus for processing the baseline of the time varying data by performing a Fourier transform of the baseline of the time varying data to generate said frequency varying data; and (iv) apparatus for determining the centroid of such frequency varying data.
Claim 28
Dependent Claim
161 words
Apparatus for controlling the growth of a layer of semiconductor material during the growth process, comprising: a) an energy source for subjecting the growing layer to a beam of electron energy to produce a diffraction pattern; b) apparatus for detecting variations in said electron energy beam caused by the growth process and generating a time-varying digitized voltage pattern in response thereto; c) apparatus for processing said time varying pattern to produce a frequency varying pattern corresponding thereto comprising: (i) apparatus for determining the mean of the time varying data; (ii) apparatus for determining the baseline trend of the time varying data by fitting a polynomial to the data and subtracting the baseline from the mean of the data; and (iii) apparatus for processing the baseline of the time varying data by performing a Fourier transform of the baseline of the time varying data to generate said frequency varying data; and (iv) apparatus for determining the centroid of such frequency varying data.
Claim 29
Dependent Claim
19 words
The apparatus of claim 19 wherein the data comprises only one cycle of oscillating corresponding to one growth layer.
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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) | 1995-06-16 | 1995-12-16 | 1996-06-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-06-16 | 1999-12-16 | 2000-06-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-06-16 | 2003-12-16 | 2004-06-16 | $7700.00 | Window Closed / Lapsed |