US4655875A
Expired / Lapsed
US
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Ion implantation process
Assignee: Hitachi Ltd
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Filing: 1986-03-04
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Granted: 1987-04-07
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Expires: 2006-03-04
Abstract
Abstract Ions having a high energy is implanted using a mask of a stacked film consisting of a film formed from an amorphous material and a film formed from a metal having a large mass number. In this way, penetration of ions can be prohibited by a mask having a far smaller thickness than that of the conventional mask. Thus ions having a high energy can be implanted with a very high accuracy.
Inventors
- 👤 Yasuo Wada
- 👤 Masao Tamura
- 👤 Nobuyoshi Natsuaki
- 👤 Kiyonori Ohyu
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 17:06
CPC Classifications
H; H10; H10P; H10P30/00; H10P30/20; H10P30/22; Y; Y10; Y10S; Y10S438/00; Y10S438/942; Y10S438/945
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
73 words
An ion implantation process comprising the steps of forming a stacked film of a second film formed from an amorphous material and a first film formed from a metal having a large mass number on a substrate to be ion-implanted, selectively removing a desired portion(s) of at least said first film to form an opening(s), and implanting ions with an energy of about 500 keV or more through said opening(s) in said substrate.
Claim 2
Dependent Claim
73 words
An ion implantation process comprising the steps of forming a stacked film of a second film formed from an amorphous material and a first film formed from a metal having a large mass number on a substrate to be ion-implanted, selectively removing a desired portion(s) of at least said first film to form an opening(s), and implanting ions with an energy of about 500 keV or more through said opening(s) in said substrate.
Claim 3
Dependent Claim
25 words
An ion implantation process as claimed in claim 1, wherein said ion implantation is applied after removal of said desired portion(s) of said second film.
Claim 4
Dependent Claim
25 words
An ion implantation process as claimed in claim 1, wherein said ion implantation is applied without removal of said desired portion(s) of said second film.
Claim 5
Dependent Claim
22 words
An ion implantation process as claimed in claim 1, wherein said metal is one having a mass number of 45 or more.
Claim 6
Dependent Claim
53 words
An ion implantation process as claimed in claim 1, wherein said first film has at least a thickness expressed by the following equation: ##EQU3## wherein t is a thickness (μm) of said first film, E is an acceleration energy (MeV) of ions, and k is a constant dependent on the kind of ions.
Claim 7
Dependent Claim
33 words
An ion implantation process as claimed in claim 5, wherein the value of said k is 0.9 for boron ions, 0.45 for phosphorus ions, 0.32 for arsenic ions, and 0.53 for silicon ions.
Claim 8
Dependent Claim
31 words
An ion implantation process as claimed in claim 1, wherein said metal is at least one member selected from the group consisting of tungsten, molybdenum, titanium, tantalum, gold, platinum, and lead.
Claim 9
Dependent Claim
43 words
An ion implantation process as claimed in claim 1, wherein said second film has at least a thickness expressed by the following equation: ##EQU4## wherein t' is a thickness of said second film (μm) and M is a mass number of implanted ions.
Claim 10
Dependent Claim
36 words
An ion implantation process as claimed in claim 1, wherein said amorphous material is at least one member selected from the group consisting of silicon dioxide, silicon nitride, phosphosilicate glass, organic high polymer resins, and resists.
Claim 11
Dependent Claim
24 words
An ion implantation process as claimed in claim 1, wherein said opening(s) is formed by reactive ion, micro-wave plasma, photo-excited plasma, or radical etching.
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) | 1990-04-06 | 1990-10-06 | 1991-04-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-04-06 | 1994-10-06 | 1995-04-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-04-06 | 1998-10-06 | 1999-04-07 | $7700.00 | Window Closed / Lapsed |