US4659400A
Expired / Lapsed
US
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Method for forming high yield epitaxial wafers
Assignee: Arris Technology Inc
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Filing: 1985-06-27
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Granted: 1987-04-21
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Expires: 2005-06-27
Abstract
Abstract A silicon substrate having a controlled oxygen content is sliced to form a wafer. The backside surface of the wafer is mechanically damaged for external gettering, polished, and subjected to heat for annealing to reduce strain and defects near the surface. The surface is then etched and the epitaxial layer formed by first growing an epitaxial layer, removing a substantial portion thereof, and then regrowing the layer to the required thickness. Immediately prior to device processing, an oxide layer is formed by heating the wafer, removing a portion of the epitaxial layer, and placing the wafer in an oxygen atmosphere. After a preselected time period in the oxygen atmosphere, the temperature is gradually reduced.
Inventors
- 👤 Danny Garbis
- 👤 Joseph J. Chan
- 👤 Amadeo J. Granata
- 👤 Philip Coniglione
- 👤 Thomas D. Briglia
- 👤 Lawrence E. Laterza
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 12:01
CPC Classifications
H; H10; H10P; H10P36/00; H10P36/20; H10P36/03; Y; Y10; Y10S; Y10S148/00; Y10S148/134; Y10S148/135
Claims Analysis
Total Claims: 41
Claim 1
Independent Claim
78 words
A method for forming an epitaxial wafer from a silicon substrate, the method comprising the steps of: slicing the substrate to form a wafer; annealing the wafer; and forming an epitaxial layer of given resistivity of the surface of the wafer by (a) growing an epitaxial layer of said given resistivity, (b) removing a substantial portion, but not all, of the grown epitaxial layer, and (c) regrowing the epitaxial layer of said given resistivity to the required thickness.
Claim 2
Independent Claim
78 words
A method for forming an epitaxial wafer from a silicon substrate, the method comprising the steps of: slicing the substrate to form a wafer; annealing the wafer; and forming an epitaxial layer of given resistivity of the surface of the wafer by (a) growing an epitaxial layer of said given resistivity, (b) removing a substantial portion, but not all, of the grown epitaxial layer, and (c) regrowing the epitaxial layer of said given resistivity to the required thickness.
Claim 3
Dependent Claim
18 words
The method of claim 1, further comprising the step of: forming an oxide layer on the wafer surface.
Claim 4
Dependent Claim
38 words
The method of claim 1, wherein the step of growing an epitaxial layer comprises the steps of: (1) heating the wafer; (2) growing an epitaxial layer several microns thick; (3) cooling the wafer; and (4) reheating the wafer.
Claim 5
Dependent Claim
35 words
The method of claim 1, wherein the step of removing a portion of the grown epitaxial layer comprises the step of removing substantially all of the grown epitaxial layer except for approximately one micron thereof.
Claim 6
Dependent Claim
20 words
The method of claim 1, wherein the oxygen content of the substrate is approximately 17 to 20 parts per million.
Claim 7
Dependent Claim
29 words
The method of claim 1, wherein the sliced wafer has a backside surface and further comprising the step of subjecting the backside surface of the wafer to mechanical damage.
Claim 8
Dependent Claim
53 words
The method of claim 1, wherein the step of annealing the wafer comprises the steps of: (1) heating the wafer for approximately five hours at 900° C. in a nitrogen atmosphere; (2) permitting the heated wafer to cool rapidly; (3) removing any deposited oxide from the wafer; and (4) cleaning the wafer surface.
Claim 9
Dependent Claim
31 words
The method of claim 3, wherein the step of growing an epitaxial layer further comprises the step of removing a portion of the substrate surface prior to growing the epitaxial layer.
Claim 10
Dependent Claim
29 words
The method of claim 3, wherein the step of removing a portion of the substrate surface comprises the step of removing approximately 3500 angstroms to 5000 angstroms of substrate.
Claim 11
Dependent Claim
23 words
The method of claim 3, wherein the step of heating the wafer comprises the step of heating the wafer to approximately 1100° C.
Claim 12
Dependent Claim
28 words
The method of claim 6, wherein the step of subjecting the backside surface to mechanical damage comprises the step of scribing the backside surface to form concentric circles.
Claim 13
Dependent Claim
17 words
The method of claim 6, further comprising the step of polishing the backside surface of the wafer.
Claim 14
Independent Claim
83 words
A method for forming an epitaxial wafer from a silicon substrate, the method comprising the steps of: slicing the substrate to form a wafer; annealing the wafer; forming an epitaxial layer; and forming an oxide layer on the epitaxial layer by (a) heating the wafer to a first temperature, (b) removing a portion but not all of the epitaxial layer, (c) placing the wafer in an oxygen atmosphere for a given time period, and (d) gradually reducing the temperature to a second temperature.
Claim 15
Independent Claim
83 words
A method for forming an epitaxial wafer from a silicon substrate, the method comprising the steps of: slicing the substrate to form a wafer; annealing the wafer; forming an epitaxial layer; and forming an oxide layer on the epitaxial layer by (a) heating the wafer to a first temperature, (b) removing a portion but not all of the epitaxial layer, (c) placing the wafer in an oxygen atmosphere for a given time period, and (d) gradually reducing the temperature to a second temperature.
Claim 16
Dependent Claim
28 words
The method of claim 13, wherein the step of heating the wafer comprises the step of slowly heating the wafer, in a nitrogen atmosphere, to approximately 1100° C.
Claim 17
Dependent Claim
29 words
The method of claim 13, wherein the step of removing a portion of the epitaxial layer comprises the step of etching away approximately 1200 angstroms of the epitaxial layer.
Claim 18
Dependent Claim
32 words
The method of claim 13, wherein the step of placing the wafer in an oxygen atmosphere comprises the step of heating the wafer for approximately 60 minutes in 3 liters/minute of oxygen.
Claim 19
Dependent Claim
36 words
The method of claim 13, wherein the step of gradually reducing the temperature comprises the step of reducing the temperature from approximately 1100° C. to approximately 700° C. over the time period of approximately 60 minutes.
Claim 20
Dependent Claim
28 words
The method of claim 13, wherein the step of forming an oxide layer comprises the step of forming an oxide layer from 1600 angstroms to 1800 angstroms thick.
Claim 21
Dependent Claim
25 words
The method of claim 13, wherein the step of forming an oxide layer occurs immediately prior to processing the wafer to form semiconductor devices thereon.
Claim 22
Dependent Claim
20 words
The method of claim 13, wherein the oxygen content of the substrate is approximately 17 to 20 parts per minute.
Claim 23
Dependent Claim
29 words
The method of claim 13, wherein the sliced wafer has a backside surface and further comprising the step of subjecting the backside surface of the wafer to mechanical damage.
Claim 24
Dependent Claim
53 words
The method of claim 13, wherein the step of annealing the wafer comprises the steps of: (1) heating the wafer for approximately five hours at 900° C. in a nitrogen atmosphere; (2) permitting the heated wafer to cool rapidly; (3) removing any deposited oxide from the wafer; and (4) cleaning the wafer surface.
Claim 25
Dependent Claim
21 words
The method of claim 15, wherein the step of etching comprises etching at a rate of approximately 75 angstroms per minute.
Claim 26
Dependent Claim
28 words
The method of claim 21, wherein the step of subjecting the backside surface to mechanical damage comprises the step of scribing the backside surface to form concentric circles.
Claim 27
Dependent Claim
17 words
The method of claim 21, further comprising the step of polishing the backside surface of the wafer.
Claim 28
Independent Claim
101 words
A method of forming an epitaxial wafer from a silicon substrate, the method comprising: slicing the substrate to form a wafer; annealing the wafer; forming an epitaxial layer by (a) growing an epitaxial layer, (b) removing a substantial portion but not all, of the grown layer, and (c) regrowing the epitaxial layer to the required thickness; and forming an oxide layer by (i) heating the wafer to a first temperature, (ii) removing a portion of the epitaxial layer, (iii) placing the wafer in an oxygen atmosphere for a given time period, and (iv) gradually reducing the temperature to a second temperature.
Claim 29
Independent Claim
101 words
A method of forming an epitaxial wafer from a silicon substrate, the method comprising: slicing the substrate to form a wafer; annealing the wafer; forming an epitaxial layer by (a) growing an epitaxial layer, (b) removing a substantial portion but not all, of the grown layer, and (c) regrowing the epitaxial layer to the required thickness; and forming an oxide layer by (i) heating the wafer to a first temperature, (ii) removing a portion of the epitaxial layer, (iii) placing the wafer in an oxygen atmosphere for a given time period, and (iv) gradually reducing the temperature to a second temperature.
Claim 30
Dependent Claim
38 words
The method of claim 26, wherein the step of growing an epitaxial layer comprises the steps of: (1) heating the wafer; (2) growing an epitaxial layer several microns thick; (3) cooling the wafer; and (4) reheating the wafer.
Claim 31
Dependent Claim
34 words
The method of claim 26, wherein the step of removing a portion of the grown epitaxial layer comprises the step of removing all of the grown epitaxial layer except for approximately one micron thereof.
Claim 32
Dependent Claim
31 words
The method of claim 26, wherein the step of growing an epitaxial layer further comprises the step of removing a portion of the substrate surface prior to growing the epitaxial layer.
Claim 33
Dependent Claim
29 words
The method of claim 26, wherein the sliced wafer has a backside surface and further comprising the step of subjecting the backside surface of the wafer to mechanical damage.
Claim 34
Dependent Claim
53 words
The method of claim 26, wherein the step of annealing the wafer comprises the steps of: (1) heating the wafer for approximately five hours at 900° C. in a nitrogen atmosphere; (2) permitting the heated wafer to cool rapidly; (3) removing any deposited oxide from the wafer; and (4) cleaning the wafer surface.
Claim 35
Dependent Claim
28 words
The method of claim 26, wherein the step of heating the wafer comprises the step of slowly heating the wafer, in a nitrogen atmosphere, to approximately 1100° C.
Claim 36
Dependent Claim
29 words
The method of claim 26, wherein the step of removing a portion of the epitaxial layer comprises the step of etching away approximately 1200 angstroms of the epitaxial layer.
Claim 37
Dependent Claim
31 words
The method of claim 26, wherein step of placing the wafer in an oxygen atmosphere comprises the step of heating the wafer for approximately 60 minutes in 3 liters/minute of oxygen.
Claim 38
Dependent Claim
36 words
The method of claim 26, wherein the step of gradually reducing the temperature comprises the step of reducing the temperature from approximately 1100° C. to approximately 700° C. over the time period of approximately 60 minutes.
Claim 39
Dependent Claim
28 words
The method of claim 26, wherein the step of forming an oxide layer comprises the step of forming an oxide layer from 1600 angstroms to 1800 angstroms thick.
Claim 40
Dependent Claim
25 words
The method of claim 26, wherein the step of forming an oxide layer occurs immediately prior to processing the wafer to form semiconductor devices thereon.
Claim 41
Dependent Claim
28 words
The method of claim 30, wherein the step of subjecting the backside surface to mechanical damage comprises the step of scribing the backside surface to form concentric circles.
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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) | 1990-04-20 | 1990-10-20 | 1991-04-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-04-20 | 1994-10-20 | 1995-04-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-04-20 | 1998-10-20 | 1999-04-21 | $7700.00 | Window Closed / Lapsed |