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US5296387A
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Method of providing lower contact resistance in MOS transistor structures
Assignee: National Semiconductor Corp
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Filing: 1992-12-02
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Granted: 1994-03-22
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Expires: 2012-12-02
Abstract
Abstract Germanium is used to significantly enhance the drift mobilities of minority carriers in the channels of N-channel and P-channel metal-oxide-semiconductor (MOS) transistors with silicon substrates. Germanium processing is also used to enhance the source/drain contact conductance for MOS devices. Methods are disclosed for forming a germanium-rich interfacial layer utilizing a germanium implant and wet oxidation or growing a silicon-germanium alloy by molecular beam epitaxy.
Inventors
- 👤 Sheldon Aronowitz
- 👤 Courtney Hart
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 22:17
CPC Classifications
H; H10; H10P; H10P30/00; H10P30/20; H10P30/202; H10P30/204; H10D; H10D30/00; H10D30/01; H10D30/021; H10D30/027; H10D62/00; H10D62/80; H10D62/83; H10D62/832; H10D64/00; H10D64/01; H10D64/011; H10D64/0111; H10D64/0113; H10P14/00; H10P14/60; H10P14/63; H10P14/6302; H10P14/6304; H10P14/6306; H10P14/6308; H10P14/6309; H10P14/6322; H10P14/65; H10P14/6502; H10P30/208; Y; Y10; Y10S; Y10S148/00; Y10S148/058; Y10S148/059
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
196 words
A method of providing lower contact resistance in the source and drain regions of an MOS transistor, the method comprising the sequential steps of: (a) defining regions on a silicon substrate which will later be formed into source and drain regions through the introduction of active dopant species, the future source and drain regions being spaced apart to define a channel region therebetween; (b) after defining the future source and drain regions, introducing germanium atoms into the future source and drain regions; (c) after introducing germanium atoms into the future source and drain regions, performing an oxidation step to form an oxide layer on the future source and drain regions and to create a germanium-rich layer in the future source and drain regions at the interfacial region between the future source and drain region and the oxide layer; and (d) after performing the oxidation step, forming an MOS transistor structure having source and drain regions and a gate electrode overlying the channel region and separated therefrom by a layer of dielectric material, wherein the formation of the MOS transistor structure includes the implantation of active dopant species in order to form the source and drain regions.
Claim 2
Independent Claim
196 words
A method of providing lower contact resistance in the source and drain regions of an MOS transistor, the method comprising the sequential steps of: (a) defining regions on a silicon substrate which will later be formed into source and drain regions through the introduction of active dopant species, the future source and drain regions being spaced apart to define a channel region therebetween; (b) after defining the future source and drain regions, introducing germanium atoms into the future source and drain regions; (c) after introducing germanium atoms into the future source and drain regions, performing an oxidation step to form an oxide layer on the future source and drain regions and to create a germanium-rich layer in the future source and drain regions at the interfacial region between the future source and drain region and the oxide layer; and (d) after performing the oxidation step, forming an MOS transistor structure having source and drain regions and a gate electrode overlying the channel region and separated therefrom by a layer of dielectric material, wherein the formation of the MOS transistor structure includes the implantation of active dopant species in order to form the source and drain regions.
Claim 3
Dependent Claim
37 words
The method of claim 1, wherein the oxidation step is performed for a period of time that results in the creation of a germanium-rich layer in the future source and drain regions comprising at least 70% germanium.
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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) | 1997-03-21 | 1997-09-20 | 1998-03-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-03-21 | 2001-09-20 | 2002-03-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-03-21 | 2005-09-20 | 2006-03-22 | $7700.00 | Window Closed / Lapsed |