US4489479A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for repair of buried contacts in MOSFET devices
Assignee: Raytheon Co
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Filing: 1983-09-01
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Granted: 1984-12-25
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Expires: 2003-09-01
Abstract
Abstract Contacts between polysilicon conductors on the surface of a silicon wafer and doped regions underlying them in the wafer, rendered defective by the growth of a thin intervening oxide layer between conductors and diffusions, are repaired by depositing dots of aluminum on the conductors in the contact areas and annealing the wafer so as to drive traces of the aluminum through the conductors and the intervening oxide into the underlying doped regions in the wafer.
Inventors
- 👤 Steven E. Shields
- 👤 David A. Robinson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 19:43
CPC Classifications
H; H10; H10W; H10W20/00; H10W20/01; H10W20/021; H10W20/031; H10W20/064; H10W20/065
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
121 words
A method of overcoming the effect of an undesirably intervening oxide layer in a silicon wafer of integrated circuits between a defined conductive area of a layer of polycrystalline silicon which extends over a surface of said wafer and a doped region in said wafer underlying said defined area, said oxide layer interfering with the creation of a contact between said polycrystalline silicon and said doped region in said defined area, comprising the steps of: (a) depositing a dot of aluminum on said polycrystalline silicon layer on said defined area; and (b) annealing said wafer at an elevated temperature so as to drive said aluminum into said doped region through said polycrystalline silicon layer and through said undesirably intervening oxide layer.
Claim 2
Independent Claim
121 words
A method of overcoming the effect of an undesirably intervening oxide layer in a silicon wafer of integrated circuits between a defined conductive area of a layer of polycrystalline silicon which extends over a surface of said wafer and a doped region in said wafer underlying said defined area, said oxide layer interfering with the creation of a contact between said polycrystalline silicon and said doped region in said defined area, comprising the steps of: (a) depositing a dot of aluminum on said polycrystalline silicon layer on said defined area; and (b) annealing said wafer at an elevated temperature so as to drive said aluminum into said doped region through said polycrystalline silicon layer and through said undesirably intervening oxide layer.
Claim 3
Dependent Claim
73 words
The method of claim 1 characterized in that said silicon wafer of integrated circuits includes a plurality of contacts of which some are defective and in that said step of depositing a dot of aluminum includes the steps of: (a) forming a masking layer over said polycrystalline silicon layer, patterned with openings which overlie at least said defective contacts; and (b) selectively depositing said aluminum through said mask opening onto said defective contacts.
Claim 4
Dependent Claim
41 words
The method of claim 2 characterized further in that said masking layer is formed by depositing a photoresist layer over said wafer and selectively exposing it to radiation through a mask patterned with openings corresponding to the location of said contacts.
Claim 5
Dependent Claim
56 words
The method of claim 3 including the additional step of removing residues of said aluminum from the wafer after said annealing step and limiting the temperatures to which said device is subjected during subsequent processing steps to those below the temperature at which said aluminum is further driven through said doped region into said silicon wafer.
Claim 6
Dependent Claim
68 words
The method of claim 1 characterized further in that said silicon wafer of integrated circuits includes a plurality of contacts only some of which are defective and in that during said depositing step dots of aluminum are formed on operative as well as defective contacts on said wafer so that, during said step of annealing, said aluminum is driven into doped regions underlying both operative and defective contacts.
Claim 7
Dependent Claim
37 words
The method of claim 5 characterized further in that a common mask is used both to establish the defined areas of said polycrystalline layer and to locate the dots of aluminum which are deposited over said areas.
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) | 1987-12-25 | 1988-06-25 | 1988-12-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-12-25 | 1992-06-25 | 1992-12-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-12-25 | 1996-06-25 | 1996-12-25 | $7700.00 | Window Closed / Lapsed |