US3897276A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of implanting ions of different mass numbers in semiconductor crystals
Assignee: NEC Corp
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Filing: 1973-06-20
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Granted: 1975-07-29
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Expires: 1993-06-20
Abstract
Abstract In order to form a region of a predetermined conductivity type in a semiconductor crystal during the manufacture of an IMPATT diode, a variable capacity diode, or the like, the successive implantation of impurity ions is carried out under different implantation conditions in a manner known in the art but utilizing impurity ions of relatively high mass number, such as indium ions, for implantation in the deeper layer of the region and impurity ions of lower mass number, such as boron ions, for implantation in layers lying closer to the semiconductor crystal surface.
Inventors
- 👤 Motoki Kondo
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 06:26
CPC Classifications
H; H10; H10P; H10P30/00; H10P30/20; H10D; H10D99/00; H10P95/00; Y; Y10; Y10S; Y10S148/00; Y10S148/097; Y10S148/145
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
105 words
A METHOD OF SUCCESSIVELY IMPLANTING IMPURITY IONS IN A SEMICONDUCTOR CRYSTAL IN A PLURALITY OF IMPLANTATION STEPS USING DIFFERENT IMPLANTATION CONDITIONS TO FORM A REGION OF A PERDETERMINED CONDUCTIVITY TYPE OVER A PRESELECTED RANGE OF DEPTHS MEASURED FROM ONE OF THE SURFACES OF SAID SEMICONDUCTOR CRYSTAL, SAID REGION HAVING A PLURALITY OF LAYERS INCLUDING THE STEPS OF IMPLANTING IMPURITY IONS OF A FIRST RELATIVELY HIGH MASS NUMBER IN THE LAYER OF SAID REGION SPACED FARTHEST FROM SAID ONE SURFACE AND IMPLANTING IMPURITY IONS OF A SECOND MASS NUMBER LOWER THAN SAID FIRST MASS NUMBER IN THE LAYERS OF SAID REGION CLOSER TO SAID ONE SURFACE.
Claim 2
Independent Claim
105 words
A METHOD OF SUCCESSIVELY IMPLANTING IMPURITY IONS IN A SEMICONDUCTOR CRYSTAL IN A PLURALITY OF IMPLANTATION STEPS USING DIFFERENT IMPLANTATION CONDITIONS TO FORM A REGION OF A PERDETERMINED CONDUCTIVITY TYPE OVER A PRESELECTED RANGE OF DEPTHS MEASURED FROM ONE OF THE SURFACES OF SAID SEMICONDUCTOR CRYSTAL, SAID REGION HAVING A PLURALITY OF LAYERS INCLUDING THE STEPS OF IMPLANTING IMPURITY IONS OF A FIRST RELATIVELY HIGH MASS NUMBER IN THE LAYER OF SAID REGION SPACED FARTHEST FROM SAID ONE SURFACE AND IMPLANTING IMPURITY IONS OF A SECOND MASS NUMBER LOWER THAN SAID FIRST MASS NUMBER IN THE LAYERS OF SAID REGION CLOSER TO SAID ONE SURFACE.
Claim 3
Dependent Claim
29 words
A method as claimed in claim 1, wherein said impurity ions of said first relatively high mass number are implanted before said impurity ions of said second mass number.
Claim 4
Dependent Claim
45 words
A method as claimed in claim 2, wherein said predetermined conductivity type is p type, said impurity ions of said first relatively high mass number are indium ions, and said impurity ions of said mass number lower than said first mass number are boron ions.
Claim 5
Dependent Claim
88 words
A method as claimed in claim 3, wherein said indium ions are implanted in said semiconductor crystal using an accelerating energy of 950 keV, at a dose level of 4 X 1012 ions/cm2 and said boron ions are first implanted in said crystal using an accelerating energy of 60 keV, at a dose level of 4 X 1012 ions/cm2, and said boron ions are then implanted a second time in said crystal using an accelerating energy of 30 keV at a dose level of 2.5 X 1012 ions/cm2.
Claim 6
Dependent Claim
35 words
A method as claimed in claim 4, including the additional step of implanting said boron atoms a third time using an accelerating energy of 10 keV and a dose level of 1 X 1015 ions/cm2.
Claim 7
Dependent Claim
30 words
A method as claimed in claim 5, including the additional step of heating said semiconductor crystal for approximately 10 minutes at a temperature of approximately 900*C in a nitrogen atmosphere.
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) | 1978-07-28 | 1979-01-27 | 1979-07-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-07-28 | 1983-01-27 | 1983-07-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-07-28 | 1987-01-27 | 1987-07-29 | $7700.00 | Window Closed / Lapsed |