US3852128A
Expired / Lapsed
US
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Method of diffusing impurities into semiconductor wafers
Assignee: Telefunken Electronic GmbH
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Filing: 1972-04-17
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Granted: 1974-12-03
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Expires: 1992-04-17
Abstract
Abstract A method of diffusing impurities into semiconductor wafers comprises carrying out the diffusion in a diffusion chamber using doped semiconductor material in wafer form as a doping source. The concentration impurities at the surface of the wafers to be diffused may be controlled by the area ratio between the wafers to be diffused and the doping wafers and/or by the spatial arrangement of the wafers to be diffused and the doping wafers in the diffusion chamber.
Inventors
- 👤 K Kreuzer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 23:53
CPC Classifications
C; C30; C30B; C30B31/00; C30B31/06; C30B31/16; C30B31/165; H; H10; H10P; H10P32/00; H10P32/10; H10P32/19
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
123 words
A METHOD OF DIFFUSING IMPURITIES INTO A SEMICONDUCTOR WAFER, COMPRISING THE STEPS OF DETERMINING BY DIFFUSING IN AN EXHAUSTED AND SEALED OFF DIFFUSION CHAMBER WITH A DOPED SEMICONDUCTOR WAFER MEANS AS DOPING SOURCE AND UNDER DIFFUSION PARAMETERS OTHERWISE FIXED THE IMPURITY CONCENTRATION ACHIEVED AT THE SURFACE OF A SEMICONDUCTOR WAFER MEANS TO BE DIFFUSED AS A FUNCTION OF THE RATIO OF THE AREA OF THE DOPED SEMICONDUCTOR WAFER MEANS TO THE AREA OF SEMICONDUCTOR WAFER MEANS TO BE DIFFUSED, SELECTING A DESIRED IMPURITY CONCENTRATION FOR A GIVEN SEMICONDUCTOR WAFER MEANS TO BE DIFFUSED, AND DIFFUSING IMPURITIES INTO SAID GIVEN WAFER MEANS UNDER THE FIXED DIFFUSION PARAMETERS USED IN THE STEP OF DETERMINING AND AT THE APPROPRIATE RATIO DETERMINED IN THE STEP OF DETERMINING.
Claim 2
Independent Claim
123 words
A METHOD OF DIFFUSING IMPURITIES INTO A SEMICONDUCTOR WAFER, COMPRISING THE STEPS OF DETERMINING BY DIFFUSING IN AN EXHAUSTED AND SEALED OFF DIFFUSION CHAMBER WITH A DOPED SEMICONDUCTOR WAFER MEANS AS DOPING SOURCE AND UNDER DIFFUSION PARAMETERS OTHERWISE FIXED THE IMPURITY CONCENTRATION ACHIEVED AT THE SURFACE OF A SEMICONDUCTOR WAFER MEANS TO BE DIFFUSED AS A FUNCTION OF THE RATIO OF THE AREA OF THE DOPED SEMICONDUCTOR WAFER MEANS TO THE AREA OF SEMICONDUCTOR WAFER MEANS TO BE DIFFUSED, SELECTING A DESIRED IMPURITY CONCENTRATION FOR A GIVEN SEMICONDUCTOR WAFER MEANS TO BE DIFFUSED, AND DIFFUSING IMPURITIES INTO SAID GIVEN WAFER MEANS UNDER THE FIXED DIFFUSION PARAMETERS USED IN THE STEP OF DETERMINING AND AT THE APPROPRIATE RATIO DETERMINED IN THE STEP OF DETERMINING.
Claim 3
Dependent Claim
53 words
A method as defined in claim 1, including removing from said semiconductor source wafer means after the diffusion operation a layer, the thickness of which is greater than the depth of penetration of the impurities into the diffused wafer means, and then reusing said semiconductor source wafer means for a further diffusion operation.
Claim 4
Dependent Claim
53 words
A method as defined in claim 1, including etching from said semiconductor source wafer means after a diffusion operation a layer, the thickness of which is greater than the depth of penetration of the impurities into the diffused wafer means, and then reusing said semiconductor source wafer means for a further diffusion operation.
Claim 5
Dependent Claim
53 words
A method as defined in claim 1, including grinding from said semiconductor source wafer means after a diffusion operation a layer, the thickness of which is greater than the depth of penetration of the impurities into the diffused wafer means, and then reusing said semiconductor source wafer means for a further diffusion operation.
Claim 6
Dependent Claim
39 words
A method as defined in claim 1, wherein in the step of diffusing at the appropriate ratio the area of said semiconductor source wafer means is selected larger than the area of said semiconductor wafer means to be diffused.
Claim 7
Dependent Claim
46 words
A method as defined in claim 1, wherein in the step of diffusing at the appropriate ratio the area of said semiconductor source wafer means is selected to be from 1.3 to 5 times as large as the area of semiconductor wafer means to be diffused.
Claim 8
Dependent Claim
68 words
A method as defined in claim 1, wherein said fixed diffusion parameters include vertical setting up of said semiconductor source wafer means and said semiconductor wafer means to be diffused side by side in a wafer receiver accommodated in a quartz glass ampoule as said chamber, with the quartz glass ampoule being evacuated and heated to a predetermined temperature for a period of time which is likewise predetermined.
Claim 9
Dependent Claim
101 words
A method as defined in claim 7, wherein said fixed parameters further include the evacuation of said ampoule to 10 6 Torr, said source means being in the form of 50 individual wafers of silicon doped with boron to a concentration of 5 X 1018 atoms/cm3, said means to be diffused being in the form of 20 silicon wafers placed in the middle of the 50 source wafers, a diffusion time of 1 hour at a temperature of 1,200*C, and the ratio of the area of source wafers to the area of wafers to Be diffused lying between 1.3 and 5.
Claim 10
Dependent Claim
103 words
In a method for diffusing impurities into semiconductor wafers in an exhausted and sealed off diffusion chamber, in which method semiconductor wafers doped with the impurities are provided as doping source, the improvement comprising carrying out the diffusion with the ratio of the area of doped semiconductor wafer to the area of semiconductor wafer to be diffused, FQ/FD, lying in a region in which increases in the ratio FQ/FD result in increases in the impurity surface concentration of the wafers being diffused and in which decreases in the ratio FQ/FD result in decreases in the impurity surface concentration of the wafers being diffused.
Claim 11
Dependent Claim
103 words
In a method for diffusing impurities into semiconductor wafers in an exhausted and sealed off diffusion chamber, in which method semiconductor wafers doped with the impurities are provided as doping source, the improvement comprising carrying out the diffusion with the ratio of the area of doped semiconductor wafer to the area of semiconductor wafer to be diffused, FQ/FD, lying in a region in which increases in the ratio FQ/FD result in increases in the impurity surface concentration of the wafers being diffused and in which decreases in the ratio FQ/FD result in decreases in the impurity surface concentration of the wafers being diffused.
Claim 12
Dependent Claim
19 words
In a method as claimed in claim 9, the further improvement that the ratio FQ/FD is less than 4.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-12-02 | 1978-06-03 | 1978-12-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-12-02 | 1982-06-03 | 1982-12-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-12-02 | 1986-06-03 | 1986-12-03 | $7700.00 | Window Closed / Lapsed |