US4713140A
Expired / Lapsed
US
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Laser luminescence monitor for material thickness
Assignee: International Business Machines Corp
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Filing: 1987-03-02
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Granted: 1987-12-15
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Expires: 2007-03-02
Abstract
Abstract An apparatus and method for monitoring a change of thickness of a first material with a first bandgap energy, for disposal over a second material on a wafer and having a second different bandgap energy, wherein at least one of the materials has a direct bandgap. The apparatus comprises means for changing the thickness of the first material layer; means for directing a beam of energy to impinge at an angle on to the surface and to penetrate the wafer, with the beam having an energy sufficient to pump the at least one direct bandgap material to a higher energy state; and means for detecting the induced luminescence from the at least one direct bandgap material to determine when to alter the thickness changing process. The present invention may be used to monitor both deposition and etching processes. It is particularly suited for determining the etch endpoint for III-V semiconductor materials such as GaAs and AlGaAs.
Inventors
- 👤 Zu-Jean Tien
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 17:43
CPC Classifications
G; G01; G01B; G01B11/00; G01B11/02; G01B11/06; G01B11/0616; G01B11/0658
Claims Analysis
Total Claims: 41
Claim 1
Independent Claim
161 words
An apparatus for monitoring a change of thickness of a first material layer having a first bandgap wavelength energy, said first material layer for disposal over a second material layer on a wafer and having a second different bandgap wavelength energy, wherein at least one of said materials has a direct bandgap, comprising: means for holding said wafer and for changing the thickness of said first material layer at a particular location over said second material layer; means for generating a beam of energy of an intensity and wavelength sufficient to pump said at least one direct bandgap material to a higher energy state; means for directing said beam of energy to impinge at an angle on to the surface and to penetrate said wafer at said location wherein said first material layer thickness is being changed; and means for detecting induced luminescence from said at least one direct bandgap material layer to determine when to stop said thickness changing means.
Claim 2
Independent Claim
161 words
An apparatus for monitoring a change of thickness of a first material layer having a first bandgap wavelength energy, said first material layer for disposal over a second material layer on a wafer and having a second different bandgap wavelength energy, wherein at least one of said materials has a direct bandgap, comprising: means for holding said wafer and for changing the thickness of said first material layer at a particular location over said second material layer; means for generating a beam of energy of an intensity and wavelength sufficient to pump said at least one direct bandgap material to a higher energy state; means for directing said beam of energy to impinge at an angle on to the surface and to penetrate said wafer at said location wherein said first material layer thickness is being changed; and means for detecting induced luminescence from said at least one direct bandgap material layer to determine when to stop said thickness changing means.
Claim 3
Dependent Claim
41 words
An apparatus as defined in claim 1, wherein said detecting means includes means for detecting induced luminescence from a direct bandgap second material; and further comprising means for varying the second material induced luminescence detection capability through said first material layer.
Claim 4
Dependent Claim
57 words
An apparatus as defined in claim 1, wherein said detecting means includes means for detecting induced luminescence from a direct bandgap second material; and further including means for varying the angle at which said beam of energy impinges on the surface of said wafer to thereby vary the depth to which said beam penetrates into said wafer.
Claim 5
Dependent Claim
26 words
An apparatus as defined in claim 1, wherein said thickness changing means comprises means for depositing said first material layer on to said second material layer.
Claim 6
Dependent Claim
41 words
An apparatus as defined in claim 4, wherein said detecting means includes means for detecting induced luminescence from a direct bandgap second material; and further comprising means for varying the second material induced luminescence detection capability through said first material layer.
Claim 7
Dependent Claim
57 words
An apparatus as defined in claim 4, wherein said detecting means includes means for detecting induced luminescence from a direct bandgap second material; and further including means for varying the angle at which said beam of energy impinges on the surface of said wafer to thereby vary the depth to which said beam penetrates into said wafer.
Claim 8
Dependent Claim
24 words
An apparatus as defined in claim 1, wherein said thickness changing means comprises means for reducing the thickness of an existing first material layer.
Claim 9
Dependent Claim
41 words
An apparatus as defined in claim 7, wherein said detecting means includes means for detecting induced luminescence from a direct bandgap second material; and further comprising means for varying the second material induced luminescence detection capability through said first material layer.
Claim 10
Dependent Claim
57 words
An apparatus as defined in claim 7, wherein said detecting means includes means for detecting induced luminescence from a direct bandgap second material; and further including means for varying the angle at which said beam of energy impinges on the surface of said wafer to thereby vary the depth to which said beam penetrates into said wafer
Claim 11
Dependent Claim
64 words
An apparatus as defined in claim 1, wherein said energy beam generating means includes means for generating an energy beam that includes energy of an intensity and wavelength sufficient to pump said first material layer with a first direct bandgap wavelength energy to a higher energy state; and wherein said detecting means includes means for detecting induced luminescence from said pumped first material layer.
Claim 12
Dependent Claim
64 words
An apparatus as defined in claim 7, wherein said energy beam generating means includes means for generating an energy beam that includes energy of an intensity and wavelength sufficient to pump said first material layer with a first direct bandgap wavelength energy to a higher energy state; and wherein said detecting means includes means for detecting induced luminescence from said pumped first material layer.
Claim 13
Dependent Claim
40 words
An apparatus as defined in claim 11, wherein said detecting means further includes means for changing the operation of said thickness reducing means a predetermined time after said first material induced luminescence is no longer detected above a predetermined threshold.
Claim 14
Dependent Claim
56 words
An apparatus as defined in claim 11, wherein said energy beam generating means includes means for generating an energy beam of an intensity and wavelength sufficient to pump a direct bandgap second material layer to a higher energy state; and wherein said detecting means includes means for detecting induced luminescence from said pumped second material layer.
Claim 15
Dependent Claim
53 words
An apparatus as defined in claim 13, wherein said detecting means further includes means for changing the operation of said thickness reducing means a predetermined time after both said first material luminescence is no longer detected above a predetermined threshold and said second material induced luminescence is first detected above a predetermined threshold.
Claim 16
Dependent Claim
56 words
An apparatus as defined in claim 1, wherein said energy beam generating means includes means for generating an energy beam of an intensity and wavelength sufficient to pump a direct bandgap second material layer to a higher energy state; and wherein said detecting means includes means for detecting induced luminescence from said pumped second material layer.
Claim 17
Dependent Claim
56 words
An apparatus as defined in claim 4, wherein said energy beam generating means includes means for generating an energy beam of an intensity and wavelength sufficient to pump a direct bandgap second material layer to a higher energy state; and wherein said detecting means includes means for detecting induced luminescence from said pumped second material layer.
Claim 18
Dependent Claim
56 words
An apparatus as defined in claim 7, wherein said energy beam generating means includes means for generating an energy beam of an intensity and wavelength sufficient to pump a direct bandgap second material layer to a higher energy state; and wherein said detecting means includes means for detecting induced luminescence from said pumped second material layer.
Claim 19
Dependent Claim
39 words
An apparatus as defined in claim 17, wherein said detecting means further includes means for changing the operation of said thickness reducing means a predetermined time after said second material induced luminescence is first detected above a predetermined threshold.
Claim 20
Dependent Claim
39 words
An apparatus as defined in claim 18, including means for varying the angle at which said beam of energy impinges on the surface of said wafer to thereby vary the depth to which said beam penetrates into said wafer.
Claim 21
Dependent Claim
20 words
An apparatus as defined in claim 7, wherein said thickness reducing means comprises means for reactive ion etching said wafer.
Claim 22
Dependent Claim
56 words
An apparatus as defined in claim 1, wherein said energy beam generating means includes means for generating said energy beam to include energy of an intensity and wavelength sufficient to pump a material layer of AlGaAs to a higher energy level; and wherein said detecting means includes means for detecting induced luminescence from said pumped AlGaAs.
Claim 23
Dependent Claim
57 words
An apparatus as defined in claim 1, wherein said energy beam generating means further comprises means for generating an energy beam that includes energy of an intensity and wavelength sufficient to pump a direct bandgap for GaAs to a higher energy level; and wherein said detecting means includes means for detecting induced luminescence from said pumped GaAs.
Claim 24
Dependent Claim
55 words
An apparatus as defined in claim 22, wherein said energy beam generating means includes means for generating said energy beam to include energy of an intensity and wavelength to pump a material layer of AlGaAs to a higher energy level; and wherein said detecting means includes means for detecting induced luminescence from said pumped AlGaAs.
Claim 25
Dependent Claim
51 words
An apparatus as defined in claim 1, wherein said energy beam generating means comprises means for generating an energy beam of an intensity and with wavelengths sufficient to pump first and second direct bandgaps of first and second material layers, respectively, wherein both of said material layers are III-V semiconductor compounds.
Claim 26
Independent Claim
159 words
A method for monitoring a change in thickness of a first material layer with a first bandgap energy, said first material layer for disposal over a second material layer formed on a wafer, with said second material layer having a different bandgap energy, wherein at least one of said material bandgaps is a direct bandgap, comprising the steps of: changing the thickness of said first material layer having said first bandgap energy at a particular location over said second material layer; generating a beam of energy of an intensity and wavelength sufficient to pump said at least one direct bandgap material layer to a higher energy state; directing said beam of energy to impinge at an angle on to the surface and to penetrate said wafer at said location where said first material thickness is being changed; and detecting induced luminescence from said at least one direct bandgap material layer to determine when to alter said thickness changing step.
Claim 27
Independent Claim
159 words
A method for monitoring a change in thickness of a first material layer with a first bandgap energy, said first material layer for disposal over a second material layer formed on a wafer, with said second material layer having a different bandgap energy, wherein at least one of said material bandgaps is a direct bandgap, comprising the steps of: changing the thickness of said first material layer having said first bandgap energy at a particular location over said second material layer; generating a beam of energy of an intensity and wavelength sufficient to pump said at least one direct bandgap material layer to a higher energy state; directing said beam of energy to impinge at an angle on to the surface and to penetrate said wafer at said location where said first material thickness is being changed; and detecting induced luminescence from said at least one direct bandgap material layer to determine when to alter said thickness changing step.
Claim 28
Dependent Claim
38 words
A method as defined in claim 25, further including the step of varying the angle at which said beam of energy impinges on the surface of said wafer to thereby vary the depth to which said beam penetrates.
Claim 29
Dependent Claim
27 words
A method as defined in claim 25, wherein said thickness changing step comprises the step of depositing said first material layer on to said second material layer.
Claim 30
Dependent Claim
41 words
A method as defined in claim 27, further including the step of varying the angle at which said beam of energy impinges on the surface of said wafer to thereby vary the depth to which said beam penetrates into said wafer.
Claim 31
Dependent Claim
86 words
A method as defined in claim 27, wherein said beam generating step comprises the step of generating a beam with an energy and a wavelength sufficient to pump a direct bandgap second material to a higher energy state; and wherein said detecting step includes the step of detecting induced luminescence from said second material; and wherein said detecting step further includes the step of changing a depositing parameter in said depositing step a predetermined time after said second material induced luminescence drops below a predetermined threshold.
Claim 32
Dependent Claim
26 words
A method as defined in claim 25, wherein said thickness changing step comprises the step of reducing the thickness of an already present first material layer.
Claim 33
Dependent Claim
38 words
A method as defined in claim 30, further including the step of varying the angle at which said beam of energy impinges on the surface of said wafer to thereby vary the depth to which said beam penetrates.
Claim 34
Dependent Claim
57 words
A method as defined in claim 30, wherein said beam generating step includes the step of generating an energy beam of an intensity and wavelength sufficient to pump a direct bandgap second material layer to a higher energy state; and wherein said detecting step includes the step of detecting induced luminescence from said pumped second material layer.
Claim 35
Dependent Claim
41 words
A method as defined in claim 32, wherein said detecting step includes the step of changing a thickness reducing parameter in said thickness reducing step a predetermined time after said second material induced luminescence is first detected above a predetermined threshold.
Claim 36
Dependent Claim
58 words
A method as defined in claim 32, wherein said beam generating step includes the step of generating an energy beam with an energy and a wavelength sufficient to pump a direct bandgap first material layer to a higher energy state; and wherein said detecting step further includes the step of detecting induced luminescence from said pumped first material.
Claim 37
Dependent Claim
53 words
A method as defined in claim 34, wherein said detecting step includes the step of changing a thickness reducing parameter in said thickness reducing step a predetermined time after said first material luminescence is no longer detected above a predetermined threshold and said second material induced luminescence is detected above a predetermined threshold.
Claim 38
Dependent Claim
21 words
A method as defined in claim 30, wherein said thickness reducing step comprises the step of reactive ion etching said wafer.
Claim 39
Dependent Claim
52 words
A method as defined in claim 25, wherein said energy beam generating step comprises the step of generating an energy beam with an energy and a wavelength sufficient to pump AlGaAs to a higher energy state; and wherein said detecting step includes the step of detecting induced luminescence from said pumped AlGaAs.
Claim 40
Dependent Claim
53 words
A method as defined in claim 25, wherein said energy beam generating step comprises the step of generating an energy beam with an energy and a wavelength sufficient to pump GaAs to a higher energy state; and wherein said detecting step further includes the step of detecting induced luminescence from said pumped GaAs.
Claim 41
Dependent Claim
58 words
A method as defined in claim 25, wherein said energy beam generating step includes the step of generating said energy beam with an energy and wavelengths sufficient to pump GaAs and AlGaAs to higher energy states; and wherein said detecting step includes the step of monitoring induced luminescence wavelength peaks for each of said pumped GaAs and AlGaAs.
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