US4247373A
Expired / Lapsed
US
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Method of making semiconductor device
Assignee: Panasonic Holdings Corp
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Filing: 1979-06-12
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Granted: 1981-01-27
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Expires: 1999-06-12
Abstract
Abstract An epitaxial layer having a specified conductivity type formed on a semiinsulative or high resistivity semiconductor substrate or insulative substrate is anodized (anodically oxidized) by a predetermined D.C. current under an illumination of light of a predetermined intensity, thereby a depletion layer is formed beneath an oxide layer, which is formed by the anodizing, and the anodizing ceases in areas where the bottom face of the depletion layer reaches the semiinsulative or high resistivity semiconductor substrate or insulative substrate thus retaining a layer of highly uniform thickness layer of the epitaxial grown layer on the substrate.
Inventors
- 👤 Akio Shimano
- 👤 Hiromitsu Takagi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 18:40
CPC Classifications
H; H10; H10D; H10D1/00; H10D1/01; H10D1/025; H10D30/00; H10D30/01; H10D30/061; H10D30/0612; H10P; H10P50/00; H10P50/20; H10P50/28; H10P50/282; H10P50/283; H10P50/60; H10P50/61; H10P50/617; H10P14/00; H10P14/60; H10P14/63; H10P14/6302; H10P14/6304; H10P14/6306; H10P14/6312; H10P14/6324
Claims Analysis
Total Claims: 44
Claim 1
Independent Claim
128 words
A method of making a semiconductor device comprising the anodic oxidation of an n-conductivity type semiconductor layer formed on a substrate selected from the group consisting of a semi-insulative substrate, a high resistivity semiconductor substrate and an insulative substrate, said method characterized in that the anodic oxidation includes the steps of: maintaining an electrolytic current for the anodic oxidation in an electrolyte at a predetermined constant value, illuminating the face of the semiconductor layer to be anodically oxidized with a light of a predetermined intensity and forming a depletion layer of a specified thickness therein, and continuing said anodic oxidation until the bottom face of said depletion layer reaches an interface between said n-conductivity type semiconductor layer and said substrate and a uniform anodic oxidation layer is produced.
Claim 2
Independent Claim
128 words
A method of making a semiconductor device comprising the anodic oxidation of an n-conductivity type semiconductor layer formed on a substrate selected from the group consisting of a semi-insulative substrate, a high resistivity semiconductor substrate and an insulative substrate, said method characterized in that the anodic oxidation includes the steps of: maintaining an electrolytic current for the anodic oxidation in an electrolyte at a predetermined constant value, illuminating the face of the semiconductor layer to be anodically oxidized with a light of a predetermined intensity and forming a depletion layer of a specified thickness therein, and continuing said anodic oxidation until the bottom face of said depletion layer reaches an interface between said n-conductivity type semiconductor layer and said substrate and a uniform anodic oxidation layer is produced.
Claim 3
Dependent Claim
69 words
A method of making a semiconductor device in accordance with claim 1, wherein prior to said anodic oxidation, anodically oxidizing under an illumination intensity greater than that of said predetermined intensity while avoiding forming said depletion layer, and thereafter changing the illumination intensity from said sufficiently greater value to a lower value, wherein the illumination intensity is set when the anodic oxidation voltage increases by a predetermined voltage difference.
Claim 4
Dependent Claim
94 words
A method of making a semiconductor device in accordance with claim 1 or 2, including forming an insulation film on said n-conductivity type semiconductor layer prior to said anodic oxidation, said insulation film having an opening, through which said anodic oxidation of said n-conductivity type semiconductor layer is made, and subsequent to said anodic oxidation, removing the resultant anodically oxidized layer thereby to form a recess, forming a gate electrode in said recess, and forming a source electrode and a drain electrode on said n-conductivity type semiconductor layer on both sides of said recess.
Claim 5
Dependent Claim
75 words
A method of making a semiconductor device in accordance with claim 1 or 2, including forming an insulation film on said n-conductivity type semiconductor layer prior to said anodic oxidation, said insulation film having an opening, through which said anodic oxidation of said n-conductivity type semiconductor layer is made, and after said anodic oxidation, forming electrodes on said n-conductivity type semiconductor layer on both sides of said recess, thereby forming a resistor between said electrodes.
Claim 6
Dependent Claim
19 words
A method of making a semiconductor device in accordance with claim 4, said insulation film is a photoresist film.
Claim 7
Dependent Claim
28 words
A method of making a semiconductor device in accordance with claim 1 or 2, wherein said substrate is a semi-insulative GaAs substrate, and said n-conductivity type GaAs layer.
Claim 8
Dependent Claim
21 words
A method of making a semiconductor device in accordance with claim 1 or 2, wherein said light is a white light.
Claim 9
Dependent Claim
39 words
A method of making a semiconductor device in accordance with claim 1 or 2, wherein the illumination intensity of said light on the n-conductivity type semiconductor layer surface for said anodic oxidation is between 100 lx to 10,000 lx.
Claim 10
Dependent Claim
30 words
A method of making a semiconductor device in accordance with claim 1 or 2, wherein the temperature of the electrolyte of anodic oxidation is between 0° C. and 60° C.
Claim 11
Dependent Claim
19 words
A method of making a semiconductor device in accordance with claim 3 said insulation film is a photoresist film
Claim 12
Independent Claim
224 words
A method of making a semiconductor device having a uniform layer thickness comprising anodically oxidizing in an electrolyte under light illumination an impurity-containing n-type semiconductor layer that is formed on a substrate, the substrate selected from the group consisting of a semi-insulative substrate, a high resistivity semiconductor substrate and an insulative substrate, said method characterized in that the anodic oxidation includes steps of: A. maintaining an electrolyte current for the anodic oxidation at a predetermined constant value while conducting said oxidation, B. illuminating the surface of said n-type semiconductor layer with a predetermined constant light intensity and forming a depletion layer under the anodically oxidized layer at the surface of said n-type semiconductor layer, the thickness of said depletion layer being determined by (1) said predetermined constant value of said electrolytic current, (2) said predetermined constant light intensity and (3) the impurity concentration in said n-type semiconductor layer, C. continuing said anodic oxidation until all parts of the bottom face of said depletion layer apart from said anodically oxidized layer and inside said n-type semiconductor layer reach an interface between said n-type semiconductor layer and said substrate resulting in a layer of a uniform thickness equal to that of said depletion layer under said anodically oxidized layer, said predetermined constant light intensity providing the uniform thickness for said layer under said anodically oxidized layer.
Claim 13
Independent Claim
224 words
A method of making a semiconductor device having a uniform layer thickness comprising anodically oxidizing in an electrolyte under light illumination an impurity-containing n-type semiconductor layer that is formed on a substrate, the substrate selected from the group consisting of a semi-insulative substrate, a high resistivity semiconductor substrate and an insulative substrate, said method characterized in that the anodic oxidation includes steps of: A. maintaining an electrolyte current for the anodic oxidation at a predetermined constant value while conducting said oxidation, B. illuminating the surface of said n-type semiconductor layer with a predetermined constant light intensity and forming a depletion layer under the anodically oxidized layer at the surface of said n-type semiconductor layer, the thickness of said depletion layer being determined by (1) said predetermined constant value of said electrolytic current, (2) said predetermined constant light intensity and (3) the impurity concentration in said n-type semiconductor layer, C. continuing said anodic oxidation until all parts of the bottom face of said depletion layer apart from said anodically oxidized layer and inside said n-type semiconductor layer reach an interface between said n-type semiconductor layer and said substrate resulting in a layer of a uniform thickness equal to that of said depletion layer under said anodically oxidized layer, said predetermined constant light intensity providing the uniform thickness for said layer under said anodically oxidized layer.
Claim 14
Dependent Claim
80 words
A method of making a semiconductor device having a uniform layer thickness in accordance with claim 11 further comprising prior to said anodic oxidation, the preceding step of anodically oxidizing with an illumination intensity sufficiently greater than that of said predetermined intensity while avoiding forming said depletion layer, and thereafter reducing the illumination intensity from said sufficiently greater value to a lower value, wherein the illumination intensity is set when the anodic oxidation voltage increases by a predetermined voltage difference.
Claim 15
Dependent Claim
98 words
A method of making a semiconductor device having a uniform layer thickness in accordance with claim 11 or 12, further comprising, prior to said anodic oxidation, the preceding step of forming an insulation film on said n-type semiconductor layer, said insulation film having an opening through which said anodic oxidation of said n-type semiconductor layer is made, removing the resultant anodically oxidized layer after said anodic oxidation thereby forming a recess, forming a gate electrode in said recess, and forming a source electrode and a drain electrode on said n-type semiconductor layer on both sides of said recess.
Claim 16
Dependent Claim
84 words
A method of making a semiconductor device having a uniform layer thickness in accordance with claim 11 or 12, further comprising, prior to said anodic oxidation, the preceding step of forming an insulation film on said n-type semiconductor layer, said insulation film having an opening through which said anodic oxidation of said n-type semiconductor layer is made, and after said anodic oxidation is complete, forming electrodes on said n-type semiconductor layer on both sides of said recess, thereby forming a resistor between said electrodes.
Claim 17
Dependent Claim
37 words
A method of making a semiconductor device having a uniform layer thickness in accordance with claim 11 or 12, wherein said substrate is a semi-insulative GaAs substrate, and said n-type semiconductor layer is an n-type GaAs layer.
Claim 18
Dependent Claim
26 words
A method of making a semiconductor device having a uniform layer thickness in accordance with claim 11 or 12, wherein said light is a white light.
Claim 19
Dependent Claim
39 words
A method of making a semiconductor device having a uniform layer thickness in accordance with claim 11 or 12, wherein said illumination intensity for said anodic oxidation on said n-type semiconductor layer is between 100 lx to 100,000 lx.
Claim 20
Dependent Claim
36 words
A method of making a semiconductor device having a uniform layer thickness in accordance with claim 11 or 12, wherein the temperature of said electrolyte in said anodic oxidation is between 0° C. and 60° C.
Claim 21
Dependent Claim
25 words
A method of making a semiconductor device having a uniform layer thickness in accordance with claim 13, wherein said insulation film is a photoresist film.
Claim 22
Dependent Claim
24 words
A method of making a semiconductor device having a uniform layer thickness in accordance with claim 14, said insulation film is a photoresist film.
Claim 23
Independent Claim
228 words
A method of making a compound semiconductor device having a uniform layer thickness comprising anodically oxidizing in an electrolyte under light illumination an impurity-containing n-type compound semiconductor layer formed on a substrate selected from the group consisting of a semi-insulative substrate, a high resistivity compound semiconductor substrate and an insulative substrate, said method characterized in that the anodic oxidation includes the steps of: A. maintaining an electrolytic current for the anodic oxidation at a predetermined constant value while conducting said oxidation, B. illuminating the surface of said n-type compound semiconductor layer with a light of a predetermined constant intensity and forming a depletion layer under the anodically oxidized layer at the surface of said n-type compound semiconductor layer, the thickness of said depletion layer being determined by said predetermined constant value of said electrolytic current, said predetermined constant light intensity and the impurity concentration in said n-type compound semiconductor layer, C. continuing said anodic oxidation until all parts of the bottom face of said depletion layer apart from said anodically oxidized layer and inside said n-type compound semiconductor layer reach an interface between said n-type compound semiconductor layer and said substrate resulting in a layer of a uniform thickness equal to that of said depletion layer under said anodically oxidized layer, said predetermined constant light intensity providing the uniform thickness for said layer under said anodically oxidized layer.
Claim 24
Independent Claim
228 words
A method of making a compound semiconductor device having a uniform layer thickness comprising anodically oxidizing in an electrolyte under light illumination an impurity-containing n-type compound semiconductor layer formed on a substrate selected from the group consisting of a semi-insulative substrate, a high resistivity compound semiconductor substrate and an insulative substrate, said method characterized in that the anodic oxidation includes the steps of: A. maintaining an electrolytic current for the anodic oxidation at a predetermined constant value while conducting said oxidation, B. illuminating the surface of said n-type compound semiconductor layer with a light of a predetermined constant intensity and forming a depletion layer under the anodically oxidized layer at the surface of said n-type compound semiconductor layer, the thickness of said depletion layer being determined by said predetermined constant value of said electrolytic current, said predetermined constant light intensity and the impurity concentration in said n-type compound semiconductor layer, C. continuing said anodic oxidation until all parts of the bottom face of said depletion layer apart from said anodically oxidized layer and inside said n-type compound semiconductor layer reach an interface between said n-type compound semiconductor layer and said substrate resulting in a layer of a uniform thickness equal to that of said depletion layer under said anodically oxidized layer, said predetermined constant light intensity providing the uniform thickness for said layer under said anodically oxidized layer.
Claim 25
Dependent Claim
81 words
A method of making a compound semiconductor device having a uniform layer thickness in accordance with claim 21, further comprising prior to said anodic oxidation, the preceding step of anodically oxidizing with an illumination intensity sufficiently greater than that of said predetermined intensity while avoiding forming said depletion layer, and thereafter reducing the illumination intensity from said sufficiently greater value to a lower value, wherein the illumination intensity is set when the anodic oxidation voltage increases by a predetermined voltage difference.
Claim 26
Dependent Claim
101 words
A method of making a semiconductor device having a uniform layer thickness in accordance with claim 21 or 22, further comprising, prior to said anodic oxidation, the preceding step of forming an insulation film on said n-type compound semiconductor layer, said insulation film having an opening through which said anodic oxidation of said n-type compound semiconductor layer is made, removing the resultant anodically oxidized layer after said anodic oxidation thereby forming a recess, forming a gate electrode in said recess, and forming a source electrode and a drain electrode on said n-type compound semiconductor layer on both sides of said recess.
Claim 27
Dependent Claim
88 words
A method of making a compound semiconductor device having a uniform layer thickness in accordance with claim 21 or 22, further comprising, prior to said anodic oxidation, the preceding step of forming an insulation film on said n-type compound semiconductor layer, said insulation film having an opening, through which said anodic oxidation of said n-type compound semiconductor layer is made, and after said anodic oxidation is complete, forming electrodes on said n-type compound semiconductor layer on both sides of said recess, thereby forming a resistor between said electrodes.
Claim 28
Dependent Claim
39 words
A method of making a compound semiconductor device having a uniform layer thickness in accordance with claim 21 or 22, wherein said substrate is a semi-insulative GaAs substrate, and said n-type compound semiconductor layer is an n-type GaAs layer.
Claim 29
Dependent Claim
27 words
A method of making a compound semiconductor device having a uniform layer thickness in accordance with claim 21 or 22, wherein said light is a white light.
Claim 30
Dependent Claim
41 words
A method of making a compound semiconductor device having a uniform layer thickness in accordance with claim 21 or 22, wherein said illumination intensity for said anodic oxidation on said n-type compound semiconductor layer is between 100 lx to 10,000 lx.
Claim 31
Dependent Claim
37 words
A method of making a compound semiconductor device having a uniform layer thickness in accordance with claim 21 or 22, wherein the temperature of said electrolyte of said anodic oxidation is between 0° C. and 60° C.
Claim 32
Dependent Claim
25 words
A method of making a compound semiconductor device having a uniform thickness in accordance with claim 23, wherein said insulation film is a photoresist film.
Claim 33
Dependent Claim
25 words
A method of making a compound semiconductor device having a uniform layer thickness in accordance with claim 24, said insulation film is a photoresist film.
Claim 34
Independent Claim
222 words
A method of making a compound semiconductor device having a uniform layer thickness comprising anodically oxidizing in an electrolyte under light illumination of an impurity-containing n-type GaAs layer formed on a substrate selected from the group consisting of a semi-insulative substrate, a high resistivity compound semiconductor substrate and an insulative substrate, said method characterized in that the anodic oxidation includes the steps of: A. maintaining an electrolyte current for the anodic oxidation at a predetermined constant value while conducting said oxidation, B. illuminating the surface of said n-type GaAs layer with a light of a predetermined constant intensity and forming a depletion layer under the anodically oxidized layer at the surface of said n-type GaAs layer, the thickness of said depletion layer being determined by said predetermined constant value of said electrolytic current, said predetermined constant light intensity and the impurity concentration in said n-type GaAs layer, C. continuing said anodic oxidation until all parts of the bottom face of said depletion layer apart from said anodically oxidized layer and inside said n-type GaAs layer reach an interface between said n-type GaAs layer and said substrate resulting in a layer of uniform thickness equal to that of said depletion layer under said anodically oxidized layer, said predetermined constant light intensity providing the uniform thickness for said layer under said anodically oxidized layer.
Claim 35
Independent Claim
222 words
A method of making a compound semiconductor device having a uniform layer thickness comprising anodically oxidizing in an electrolyte under light illumination of an impurity-containing n-type GaAs layer formed on a substrate selected from the group consisting of a semi-insulative substrate, a high resistivity compound semiconductor substrate and an insulative substrate, said method characterized in that the anodic oxidation includes the steps of: A. maintaining an electrolyte current for the anodic oxidation at a predetermined constant value while conducting said oxidation, B. illuminating the surface of said n-type GaAs layer with a light of a predetermined constant intensity and forming a depletion layer under the anodically oxidized layer at the surface of said n-type GaAs layer, the thickness of said depletion layer being determined by said predetermined constant value of said electrolytic current, said predetermined constant light intensity and the impurity concentration in said n-type GaAs layer, C. continuing said anodic oxidation until all parts of the bottom face of said depletion layer apart from said anodically oxidized layer and inside said n-type GaAs layer reach an interface between said n-type GaAs layer and said substrate resulting in a layer of uniform thickness equal to that of said depletion layer under said anodically oxidized layer, said predetermined constant light intensity providing the uniform thickness for said layer under said anodically oxidized layer.
Claim 36
Dependent Claim
83 words
A method of making a compound semiconductor device having a uniform layer thickness in accordance with claim 31, further comprising, prior to said anodic oxidation, the preceding step of anodically oxidizing with an illumination intensity sufficiently greater than that of said predetermined intensity while avoiding forming said depletion layer, and thereafter a step of shifting illuminating intensity from said sufficiently greater value to a lower value, wherein the illumination intensity is set when the anodic oxidation voltage increases by a predetermined voltage difference.
Claim 37
Dependent Claim
98 words
A method of making a semiconductor device having a uniform layer thickness in accordance with claim 31 or 32, further comprising, prior to said anodic oxidation, the preceding step of forming an insulation film on said n-type GaAs layer, said insulation film having an opening, through which said anodic oxidation of said n-type GaAs layer is made, removing the resultant anodically oxidized layer after said anodic oxidation thereby forming a recess, forming a gate electrode in said recess, and forming a source electrode and a drain electrode on said n-type GaAs layer on both sides of said recess.
Claim 38
Dependent Claim
85 words
A method of making a compound semiconductor device having a uniform layer thickness in accordance with claim 31 or 32, further comprising, prior to said anodic oxidation, the preceding step of forming an insulation film on said n-type GaAs layer, said insulation film having an opening, through which said anodic oxidation of said n-type GaAs layer is made, and after said anodic oxidation is complete, forming electrodes on said n-type GaAs layer on both sides of said recess, thereby forming a resistor between said electrodes.
Claim 39
Dependent Claim
46 words
A method of making a compound semiconductor device having a uniform layer thickness in accordance with claim 31 or 32, wherein said substrate is a semi-insulative GaAs substrate, and an impurity concentration of said semi-insulative GaAs substrate is 10 8 to 10 13 atoms.cm -3 .
Claim 40
Dependent Claim
27 words
A method of making a compound semiconductor device having a uniform layer thickness in accordance with claim 31 or 32, wherein said light is a white light.
Claim 41
Dependent Claim
40 words
A method of making a compound semiconductor device having a uniform layer thickness in accordance with claim 31 or 32, wherein said illumination intensity for said anodic oxidation on said n-type GaAs layer is between 100 lx to 10,000 lx.
Claim 42
Dependent Claim
37 words
A method of making a compound semiconductor device having a uniform layer thickness in accordance with claim 31 or 32, wherein the temperature of said electrolyte of said anodic oxidation is between 0° C. and 60° C.
Claim 43
Dependent Claim
26 words
A method of making a compound semiconductor device having a uniform layer thickness in accordance with claim 33, wherein said insulation film is a photoresist film.
Claim 44
Dependent Claim
26 words
A method of making a compound semiconductor device having a uniform layer thickness in accordance with claim 38, wherein said insulation film is a photoresist film.
References Cited (Backward Citations)
US3345274A
Cited
US3345275A
Cited
US3457148A
Cited
US3377258A
Cited
US3404073A
Cited
US4080721A
Cited
US4157610A
Cited
US4108738A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1984-01-27 | 1984-07-28 | 1985-01-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-01-27 | 1988-07-28 | 1989-01-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-01-27 | 1992-07-28 | 1993-01-27 | $7700.00 | Window Closed / Lapsed |