US5283203A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Self-aligned contact process for complementary field-effect integrated circuits
Assignee: Texas Instruments Inc
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Filing: 1992-02-28
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Granted: 1994-02-01
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Expires: 2012-02-28
Abstract
Abstract A method for making a NMOS self-aligned contact in CMOS circuits without an extra mask is described. The maskless contact technique makes use of the fact that the blanket N-type implant, self-aligned to exposed field-oxide edge, will not change the P+ diffusion to N-type. The net P+ concentration in the contact region is reduced slightly but does not degrade the PMOS device performance.
Inventors
- 👤 Manzur Gill
- 👤 Danny Shum
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 13:18
CPC Classifications
H; H10; H10W; H10W20/00; H10W20/01; H10W20/021; H10B; H10B69/00; H10W20/40; Y; Y10; Y10S; Y10S148/00; Y10S148/018; Y10S148/133
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
201 words
A process for forming at least first and second electrical contacts to the substrate of an integrated circuit, said substrate having a conductivity of a first-type, said first contact being to a first diffused region of said substrate having a conductivity of a second-type opposite said first-type, said second contact being to a second diffused region of said substrate having a conductivity of said first-type, said process comprising: forming field oxide on said substrate, except in at least a first area generally correspondent to first diffused region; using said field oxide as a mask, doping said first area with a second-type dopant; forming a layer of borophosphosilicate glass on the surface of said substrate; etching through said borophosphosilicate glass to expose said first contact region, said first contact region offset from said first area, said etching extending through at least a part of said field oxide to expose a portion of said substrate outside of said first area; and blanket implanting by self-alignment a second-type dopant in a quantity sufficiently small that said implant does not change said second diffusion region to said conductivity of said second-type and does change said part of said substrate to said conductivity of said second-type.
Claim 2
Dependent Claim
201 words
A process for forming at least first and second electrical contacts to the substrate of an integrated circuit, said substrate having a conductivity of a first-type, said first contact being to a first diffused region of said substrate having a conductivity of a second-type opposite said first-type, said second contact being to a second diffused region of said substrate having a conductivity of said first-type, said process comprising: forming field oxide on said substrate, except in at least a first area generally correspondent to first diffused region; using said field oxide as a mask, doping said first area with a second-type dopant; forming a layer of borophosphosilicate glass on the surface of said substrate; etching through said borophosphosilicate glass to expose said first contact region, said first contact region offset from said first area, said etching extending through at least a part of said field oxide to expose a portion of said substrate outside of said first area; and blanket implanting by self-alignment a second-type dopant in a quantity sufficiently small that said implant does not change said second diffusion region to said conductivity of said second-type and does change said part of said substrate to said conductivity of said second-type.
Claim 3
Dependent Claim
16 words
The process of claim 1, wherein said first-type conductivity is P-type, said second-type conductivity is N-type.
Claim 4
Dependent Claim
18 words
The process of claim 1, including, after said blanket implant, depositing a layer of metal over said substrate.
Claim 5
Dependent Claim
28 words
The process of claim 1, including, after said blanket implant, depositing a layer of metal over said substrate and patterning and etching said metal to form electrical conductors.
Claim 6
Dependent Claim
31 words
The process of claim 1, wherein said blanket implant is phosphorous on the order of 1×10 14 to 6×10 14 ions/cm 2 at an energy level of 30 to 50 KeV.
Claim 7
Dependent Claim
20 words
The process of claim 1, wherein said blanket implant is self-aligned to at least one edge of said field oxide.
Claim 8
Dependent Claim
25 words
The process of claim 1, wherein said blanket implant is followed by a low-temperature implant activation at 700° to 850° C. for about 30 minutes.
Claim 9
Dependent Claim
270 words
A process for forming at least first and second electrical contacts to the substrate of an integrated circuit, said substrate having P-type conductivity, said first contact being to a first diffused region of said substrate having N-type conductivity, said second contact being to a second diffused region of said substrate having P-type conductivity, said process comprising: forming field oxide regions on said substrate except in at least a first area; using said field oxide as a mask, doping said first area with a N-type dopant; forming a layer of borophosphosilicate glass on the surface of said substrate; etching through said borophosphosilicate glass to expose said first contact region, said first contact region offset from said first area, said etching extending through at least a part of said field oxide to expose a part of said substrate outside of said first area; and blanket implanting by self-alignment a N-type in a quantity sufficiently small that said implant does not change said second diffusion region to said conductivity of said N-type and does change said part of said substrate to said conductivity of said N-type, including, after said blanket implant, depositing a layer of metal over said substrate and patterning and etching said metal to form electrical conductors; wherein said blanket implant is phosphorous on the order of 1×10 14 to 6×10 14 ions/cm 2 at an energy level of 30 to 50 KeV; wherein said blanket implant is self-aligned to at least one edge of a said field oxide region; and wherein said blanket implant is followed by a low-temperature implant activation at 700° to 850° C. for about 30 minutes.
Claim 10
Dependent Claim
270 words
A process for forming at least first and second electrical contacts to the substrate of an integrated circuit, said substrate having P-type conductivity, said first contact being to a first diffused region of said substrate having N-type conductivity, said second contact being to a second diffused region of said substrate having P-type conductivity, said process comprising: forming field oxide regions on said substrate except in at least a first area; using said field oxide as a mask, doping said first area with a N-type dopant; forming a layer of borophosphosilicate glass on the surface of said substrate; etching through said borophosphosilicate glass to expose said first contact region, said first contact region offset from said first area, said etching extending through at least a part of said field oxide to expose a part of said substrate outside of said first area; and blanket implanting by self-alignment a N-type in a quantity sufficiently small that said implant does not change said second diffusion region to said conductivity of said N-type and does change said part of said substrate to said conductivity of said N-type, including, after said blanket implant, depositing a layer of metal over said substrate and patterning and etching said metal to form electrical conductors; wherein said blanket implant is phosphorous on the order of 1×10 14 to 6×10 14 ions/cm 2 at an energy level of 30 to 50 KeV; wherein said blanket implant is self-aligned to at least one edge of a said field oxide region; and wherein said blanket implant is followed by a low-temperature implant activation at 700° to 850° C. for about 30 minutes.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1997-01-31 | 1997-08-02 | 1998-02-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-01-31 | 2001-08-02 | 2002-02-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-01-31 | 2005-08-02 | 2006-02-01 | $7700.00 | Window Closed / Lapsed |