US4907048A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Double implanted LDD transistor self-aligned with gate
Assignee: Xerox Corp
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Filing: 1987-11-23
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Granted: 1990-03-06
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Expires: 2007-11-23
Abstract
Abstract An improved double implanted and aligned LDD transistor comprising a gate having a central alignment member and a pair of outboard alignment members having portions contiguous with the gate oxide layer. A lightly doped junction is aligned with the central alignment members and a heavily doped junction is aligned with the outboard alignment members.
Inventors
- 👤 Tiao-Yuan Huang
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 04:09
CPC Classifications
H; H10; H10D; H10D30/00; H10D30/01; H10D30/021; H10D30/0223; H10D30/0227; H10D30/60; H10D30/601; H10D30/605; H10D30/0212; Y; Y10; Y10S; Y10S257/00; Y10S257/90
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
153 words
An LDD transistor comprising a semiconductor substrate bearing thereon a gate insulating layer and a gate, characterized in that said gate includes a central portion and a pair of outboard portions straddling said central portion, each of said central and outboard portions having laterally spaced alignment edges, first doped source and drain regions in said substrate have their facing ends in alignment with said aligment edges of said central portion, second doped source and drain regions in said substrate having their facing ends in alignment with said alignment edges of said outboard portions, said first doped source and drain regions being more lightly doped than said second doped source and drain regions, and said central portion and said outboard portions each include a conductive region, contiguous with said gate insulating layer, whereby said conductive regions extend from one of said outboard portion alignment edges to the other of said outboard portion alignment edges.
Claim 2
Dependent Claim
153 words
An LDD transistor comprising a semiconductor substrate bearing thereon a gate insulating layer and a gate, characterized in that said gate includes a central portion and a pair of outboard portions straddling said central portion, each of said central and outboard portions having laterally spaced alignment edges, first doped source and drain regions in said substrate have their facing ends in alignment with said aligment edges of said central portion, second doped source and drain regions in said substrate having their facing ends in alignment with said alignment edges of said outboard portions, said first doped source and drain regions being more lightly doped than said second doped source and drain regions, and said central portion and said outboard portions each include a conductive region, contiguous with said gate insulating layer, whereby said conductive regions extend from one of said outboard portion alignment edges to the other of said outboard portion alignment edges.
Claim 3
Dependent Claim
59 words
The LDD transistor as defined in claim 1 characterized in that said gate comprises an inverse-T shape wherein the distance between said alignment edges of said central portion defines the channel length of said transistor and the distance between said alignment edges of said central and outboard portions defines the length of said lightly doped source and drain regions.
Claim 4
Dependent Claim
83 words
The LDD transistor as defined in claim 2 characterized in that said central portion has a thickness dimension, normal to said lateral dimension, which is large enough to prevent the implantation of dopant therethrough into said substrate and said outboard portions include a first section having a thickness dimension which is less than said thickness dimension of said central portion such that dopant may be implanted into said substrate therethrough so that said lightly doped source and drain regions underlie said outboard portions.
Claim 5
Dependent Claim
45 words
The LDD transistor as defined in claim 3 characterized in that said outboard portions include a second section overlying said first section and the cumulative thickness of said first and second sections is such as to prevent the implantation of dopant therethrough into said substrate.
Claim 6
Dependent Claim
34 words
The LDD transistor as defined in claim 4 characterized in that said central portion and said first section of said outboard portions are conductive and said second section of said outboard portions is insulating.
Claim 7
Dependent Claim
26 words
The LDD transistor as defined in claim 4 characterized in that said central portion and said first and second sections of said outboard portions are conductive.
Claim 8
Dependent Claim
34 words
The LDD transistor as defined in claim 4 characterized in that said central portion and said second section of said outboard portions are insulating and said first section of said outboard portions is conductive.
Claim 9
Dependent Claim
26 words
The LDD transistor as defined in claim 5 characterized in that said central portion and said first section of said outboard portions comprise different conductive materials.
Claim 10
Dependent Claim
26 words
The LDD transistor as defined in claim 6 characterized in that said central portion and said first section of said outboard portions comprise different conductive materials.
Claim 11
Dependent Claim
30 words
The LDD transistor as defined in claim 4 characterized in that said central portion comprises a stack of layers having different etch characteristics, whereby etching thereof may be accurately controlled.
Claim 12
Dependent Claim
33 words
The LDD transistor as defined in claim 10 characterized in that said stack of materials includes an insulating layer sandwiched between conductive layers, and said second section of said outboard portions is conductive.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-03-05 | 1993-09-04 | 1994-03-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-03-05 | 1997-09-04 | 1998-03-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-03-05 | 2001-09-04 | 2002-03-06 | $7700.00 | Window Closed / Lapsed |