US5354700A
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Method of manufacturing super channel TFT structure
Assignee: United Microelectronics Corp
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Filing: 1993-07-26
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Granted: 1994-10-11
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Expires: 2013-07-26
Abstract
Abstract An FET thin film transistor is formed with a channel formed of a Si/Si 1-x Ge x /Si three layer sandwich which serves as the carrier transfer channel. The percentage of germanium is preferably less than 30% and should be less than about 50%. The TFT can be structured as top gate, bottom gate or twin gate structure. The Si/Si 1-x Ge/Si sandwich layer is processed in a continuous process under computer control.
Inventors
- 👤 Heng-Sheng Huang
- 👤 Chun Y. Chang
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 21:40
CPC Classifications
H; H10; H10D; H10D30/00; H10D30/01; H10D30/021; H10D30/031; H10D30/60; H10D30/67; H10D30/674; H10D30/6741; H10D30/6748; Y; Y10; Y10S; Y10S148/00; Y10S148/15; Y10S148/16
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
84 words
A method of forming an FET semiconductor device on a substrate comprising doped silicon including forming a dielectric film on the surface of said substrate, forming a channel structure on said dielectric film by depositing a sandwich of three successive film layers of a first silicon containing layer, a silicon-germanium layer with less germanium than silicon in said silicon-germanium layer and a second silicon containing layer, and forming a gate oxide and a gate electrode juxtaposed with said sandwich of three successive film layers.
Claim 2
Independent Claim
84 words
A method of forming an FET semiconductor device on a substrate comprising doped silicon including forming a dielectric film on the surface of said substrate, forming a channel structure on said dielectric film by depositing a sandwich of three successive film layers of a first silicon containing layer, a silicon-germanium layer with less germanium than silicon in said silicon-germanium layer and a second silicon containing layer, and forming a gate oxide and a gate electrode juxtaposed with said sandwich of three successive film layers.
Claim 3
Dependent Claim
34 words
A method in accordance with claim 1 wherein the material employed to form said first silicon layer is selected from the group consisting of polysilicon and polycide and said second silicon layer is polysilicon.
Claim 4
Dependent Claim
60 words
A method in accordance with claim 1 wherein said first silicon layer is deposited within a range from 70 Å to 200 Å thick, said Si 1-x Ge x layer is deposited within a range from 50 Å to 300 Å thick, and said second silicon layer is deposited within a range from 700 Å thick to 1000 Å thick.
Claim 5
Dependent Claim
31 words
A method in accordance with claim 1 wherein said first silicon layer is 70 Å thick, the silicon-germanium layer is 100 Å thick, and said second silicon layer 250 Å thick.
Claim 6
Dependent Claim
52 words
A method in accordance with claim 1 wherein said first silicon layer is 70 Å thick, the silicon-germanium layer is 100 Å thick, and said second silicon layer 250 Å thick, said sandwich of three successive film layers being deposited by LPCVD at a temperature of between 350° C. and 620° C.
Claim 7
Dependent Claim
19 words
A method in accordance with claim 1 wherein said silicon-germanium layer comprises Si 1-x Ge x , where 0.15≦x<0.5.
Claim 8
Dependent Claim
44 words
A method in accordance with claim 1 wherein said silicon-germanium layer comprises Si 1-x Ge x , where x is less than 0.3, said sandwich of three successive film layers being deposited by LPCVD at a temperature of between 350° C. and 620° C.
Claim 9
Dependent Claim
32 words
A method in accordance with claim 5 wherein said silicon-germanium layer comprises Si 1-x Ge x , where wherein said Si 1-x Ge x has a value of x less than 0.5.
Claim 10
Dependent Claim
18 words
A method in accordance with claim 1 wherein said silicon-germanium layer comprises Si 1-x Ge x where 0.15≦x≦0.3.
Claim 11
Independent Claim
118 words
A method of forming an FET semiconductor device including a substrate comprising doped silicon with a surface forming a dielectric film on said surface of said substrate, formation on said dielectric film of a sandwich comprising a first film, an intermediate film and an upper film, said first film being a polysilicon film, said intermediate film being a silicon-germanium film with less germanium than silicon in said silicon-germanium film, and said upper film being a polysilicon film, forming a gate oxide layer structure on said upper film, forming a gate on said gate oxide, and implantation of dopant species into the source and drain regions in said device juxtaposed with said gate structure employed as a self-aligned mask.
Claim 12
Independent Claim
118 words
A method of forming an FET semiconductor device including a substrate comprising doped silicon with a surface forming a dielectric film on said surface of said substrate, formation on said dielectric film of a sandwich comprising a first film, an intermediate film and an upper film, said first film being a polysilicon film, said intermediate film being a silicon-germanium film with less germanium than silicon in said silicon-germanium film, and said upper film being a polysilicon film, forming a gate oxide layer structure on said upper film, forming a gate on said gate oxide, and implantation of dopant species into the source and drain regions in said device juxtaposed with said gate structure employed as a self-aligned mask.
Claim 13
Independent Claim
148 words
A method of forming an FET semiconductor device on a substrate comprising doped silicon including forming a dielectric film on said surface of said substrate, formation of a bottom gate structure of doped polysilicon on said dielectric film, formation of a gate oxide structure on said bottom gate structure, formation on said gate oxide structure and said dielectric film of a sandwich of a first film, an intermediate film and an upper film, said first film being a silicon containing film, said intermediate film being a silicon-germanium film with less germanium than silicon in said silicon-germanium film, and said upper film being a silicon containing film, formation of a mask on said upper film above said bottom gate, and implantation of dopant species using said mask for alignment to form source and drain regions beneath said mask juxtaposed with said bottom gate structure and said gate oxide structure.
Claim 14
Independent Claim
148 words
A method of forming an FET semiconductor device on a substrate comprising doped silicon including forming a dielectric film on said surface of said substrate, formation of a bottom gate structure of doped polysilicon on said dielectric film, formation of a gate oxide structure on said bottom gate structure, formation on said gate oxide structure and said dielectric film of a sandwich of a first film, an intermediate film and an upper film, said first film being a silicon containing film, said intermediate film being a silicon-germanium film with less germanium than silicon in said silicon-germanium film, and said upper film being a silicon containing film, formation of a mask on said upper film above said bottom gate, and implantation of dopant species using said mask for alignment to form source and drain regions beneath said mask juxtaposed with said bottom gate structure and said gate oxide structure.
Claim 15
Independent Claim
76 words
A method of forming an FET semiconductor device on a substrate comprising doped silicon including forming a dielectric film on the surface of said substrate, forming a channel structure on said dielectric film in one continuous process using silane gas and germane gas supplied to a CVD processing chamber to deposit a sandwich of three successive film layers of a first silicon film, a Si 1-x Ge x film with 0.15≦x<0.5, and a second silicon film.
Claim 16
Independent Claim
76 words
A method of forming an FET semiconductor device on a substrate comprising doped silicon including forming a dielectric film on the surface of said substrate, forming a channel structure on said dielectric film in one continuous process using silane gas and germane gas supplied to a CVD processing chamber to deposit a sandwich of three successive film layers of a first silicon film, a Si 1-x Ge x film with 0.15≦x<0.5, and a second silicon film.
Claim 17
Dependent Claim
186 words
A method in accordance with claim 12 wherein said sandwich of three successive film layers is deposited in a UHVCVD system with pure silane gas (SiH 4 ) as the source of silicon at 420° C. at a flow rate of 20 sccm at a pressure of 1 mTorr, forming said first film 250 Å thick, after 50 to 200 minutes forming said Si 1-x Ge x film a valve is opened to add germane (Ge2H6) gas to the silane (SiH 4 ) gas also at 420° C. at a flow rate of 5 sccm and a pressure of 1 mTorr, said Si 1-x Ge x film being 100 Å thick; 8 minutes after opening of said germane valve, said germane valve is tightened and closed at the source of germane gas Ge2H6; the flow rate of the Ge gas source being reduced from 5 sccm to 0 sccm over a time period of 10 minutes at a pressure of 1 mTorr; said upper film comprising polysilicon having a thickness of between 70 Å to 500 Å thick deposited from LPCVD silane gas (SiH 4 ).
Claim 18
Dependent Claim
164 words
A method in accordance with claim 12 wherein said sandwich of three successive film layers is deposited in a LPCVD system with pure silane gas (SiH 4 ) as the source of silicon at 620° C. at a flow rate of 20 sccm at a pressure of 1 mTorr, forming said first film 250 Å thick, after 50 to 200 minutes forming said Si 1-x Ge x film a valve is opened to add germane (Ge2H6) gas to the silane (SiH 4 ) gas also at 600° C. at a flow rate of 5 sccm and a pressure of 1 mTorr, said Si 1-x Ge x film being 100 Å thick, with 0.15≦x<0.2 at a deposition rate between 5 Å/minute and 20 Å/minute; 8 minutes after opening of said germane valve, said germane valve is tightened and closed at the source of germane gas Ge2H6; said upper film comprising polysilicon deposited at a rate of 5 Å/minute from LPCVD silane gas (SiH 4 ).
Claim 19
Dependent Claim
60 words
A method in accordance with claim 12 wherein said first silicon layer is deposited within a range from 70 Å to 200 Å thick, said Si 1-x Ge x layer is deposited within a range from 50 Å to 300 Å thick, and said second silicon layer is deposited within a range from 700 Å thick to 1000 Å thick.
Claim 20
Dependent Claim
31 words
A method in accordance with claim 12 wherein said first silicon layer is 70 Å thick, the silicon-germanium layer is 100 Å thick, and said second silicon layer 250 Å thick.
Claim 21
Dependent Claim
52 words
A method in accordance with claim 12 wherein said first silicon layer is 70 Å thick, the silicon-germanium layer is 100 Å thick, and said second silicon layer 250 Å thick, said sandwich of three successive film layers being deposited by LPCVD at a temperature of between 350° C. and 620° C.
Claim 22
Dependent Claim
37 words
A method in accordance with claim 12 including the steps comprising forming a gate oxide and forming a gate electrode, said gate oxide and said gate electrode being juxtaposed with said sandwich of three successive film layers.
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| 3.5 Years (Year 4) | 1997-10-10 | 1998-04-11 | 1998-10-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-10-10 | 2002-04-11 | 2002-10-11 | $3760.00 | Window Closed / Lapsed |
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