Patent EP0050751A1 successfully refreshed from Google Patents.
Patent US6846720B2 successfully refreshed from Google Patents.
US6846720B2
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Method to reduce junction leakage current in strained silicon on silicon-germanium devices
Assignee: Agency for Science, Technology and Research
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Filing: 2003-06-18
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Granted: 2005-01-25
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Expires: 2023-06-18
Abstract
Abstract A MOSFET device in strained silicon-on-SiGe and a method of forming the device are described. The said device achieves reduced junction leakage due to the lower band-gap values of SiGe. The method consists of forming isolation trenches in a composite strained-Si/SiGe substrate and growing a liner oxide by wet oxidation such that oxidation is selective to SiGe only, with negligible oxidation of silicon surfaces. Selective oxidation results in oxide encroachment under strained-Si, thereby reducing the junction area after device fabrication is completed. Reduced junction area leads to reduced n + /p or p + /n junction leakage current.
Inventors
- 👤 Narayanan Balasubramanian
- 👤 Richard Hammond
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 19:38
CPC Classifications
H; H10; H10W; H10W10/00; H10W10/10; H10W10/17; H10D; H10D30/00; H10D30/60; H10D30/751; H10D30/791; H10D30/798; H10W10/01; H10W10/011; H10W10/014; H10W10/0145; H10P; H10P14/00; H10P14/20; H10P14/32; H10P14/3202; H10P14/3204; H10P14/3211; H10P14/3242; H10P14/3244; H10P14/3251; H10P14/3254; H10P14/34; H10P14/3402; H10P14/3404; H10P14/3411; H10P14/38
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
91 words
A method of forming a strained silicon-on-SiGe device; the method comprising: forming a multiple layered silicon-germanium (SiGe) film on a semiconductor substrate; forming a silicon layer on said multiple layered silicon-germanium film to form strained-silicon; forming a shallow trench in said strained-silicon and multiple layered SiGe layers; forming an oxide liner on said shallow trench surfaces by thermal oxidation; filling and planarizing said shallow trench in said strained-silicon/multiple layered SiGe; forming a gate structure over said strained silicon-on-SiGe layer; and forming doped source and drain regions in said strained silicon-on-SiGe layer.
Claim 2
Independent Claim
91 words
A method of forming a strained silicon-on-SiGe device; the method comprising: forming a multiple layered silicon-germanium (SiGe) film on a semiconductor substrate; forming a silicon layer on said multiple layered silicon-germanium film to form strained-silicon; forming a shallow trench in said strained-silicon and multiple layered SiGe layers; forming an oxide liner on said shallow trench surfaces by thermal oxidation; filling and planarizing said shallow trench in said strained-silicon/multiple layered SiGe; forming a gate structure over said strained silicon-on-SiGe layer; and forming doped source and drain regions in said strained silicon-on-SiGe layer.
Claim 3
Dependent Claim
30 words
The method of forming a strained silicon-on-SiGe device according to claim 1 , wherein said SiGe layer is composed of two or more layers: graded composition and uniform composition layers.
Claim 4
Dependent Claim
27 words
The method of forming a strained silicon-on-SiGe device according to claim 2 , wherein thickness of said graded composition SiGe layer is approximately between 1 μm-4 μm.
Claim 5
Dependent Claim
28 words
The method of forming a strained silicon-on-SiGe device according to claim 2 , wherein said graded SiGe layer has a composition of approximately between 0 and 40% Ge.
Claim 6
Dependent Claim
30 words
The method of forming a strained silicon-on-SiGe device according to claim 2 , wherein the thickness of said uniform composition SiGe layer is approximately between 0.5 and 2 μm thick.
Claim 7
Dependent Claim
28 words
The method of forming a strained silicon-on-SiGe device according to claim 1 , wherein said silicon layer thickness over SiGe layer is approximately between 50 Åand 400 Å.
Claim 8
Dependent Claim
31 words
The method of forming a strained silicon-on-SiGe device according to claim 1 , wherein said silicon dioxide liner is formed using wet oxidation at approximately between 600° C. and 700° C.
Claim 9
Dependent Claim
22 words
The method of forming a strained silicon-on-SiGe device according to claim 7 , wherein said wet oxidation is selective to SiGe layer.
Claim 10
Dependent Claim
24 words
The method of forming a strained silicon-on-SiGe device according to claim 7 , wherein said oxidation selectivity between SiGe and silicon is approximately 100:1.
Claim 11
Dependent Claim
31 words
The method of forming a strained silicon-on-SiGe device according to claim 7 , wherein said wet oxidation produces oxide encroachment of approximately between 0.1 μm and 0.4 μm under strained-silicon layer.
Claim 12
Independent Claim
71 words
The method of forming a strained silicon-on-SiGe MOSFET device with reduced leakage current; the method comprising: forming graded and uniform composition silicon-germanium (SiGe) buffer layers on a silicon substrate, forming a silicon layer on said uniform SiGe layer to form strained-silicon; forming a shallow trench in said strained-silicon and SiGe layers; forming an oxide liner on said shallow trench surfaces; and forming the completed MOSFET device on said strained silicon-on-SiGe layer.
Claim 13
Independent Claim
71 words
The method of forming a strained silicon-on-SiGe MOSFET device with reduced leakage current; the method comprising: forming graded and uniform composition silicon-germanium (SiGe) buffer layers on a silicon substrate, forming a silicon layer on said uniform SiGe layer to form strained-silicon; forming a shallow trench in said strained-silicon and SiGe layers; forming an oxide liner on said shallow trench surfaces; and forming the completed MOSFET device on said strained silicon-on-SiGe layer.
Claim 14
Dependent Claim
31 words
The method of forming a strained silicon-on-SiGe MOSFET device according to claim 11 , wherein thickness of said graded composition SiGe buffer layer is approximately between 1 μm and 4 μm.
Claim 15
Dependent Claim
26 words
The method of forming a strained silicon-on-SiGe device according to claim 12 , wherein said graded SiGe layer has a composition from 0 to 40% Ge.
Claim 16
Dependent Claim
29 words
The method of forming a strained silicon-on-SiGe device according to claim 11 , wherein thickness of said uniform composition SiGe buffer layer is approximately between 0.5 and 2 μm.
Claim 17
Dependent Claim
30 words
The method of forming a strained silicon—on—SiGe device according to claim 11 , wherein said silicon layer thickness over uniform composition SiGe layer is approximately between 50 Åand 400 Å.
Claim 18
Dependent Claim
30 words
The method of forming a strained silicon-on-SiGe device according to claim 11 , wherein said silicon dioxide liner is formed using wet oxidation at approximately between 600 and 700° C.
Claim 19
Dependent Claim
22 words
The method of forming a strained silicon-on-SiGe device according to claim 16 , wherein said wet oxidation is selective to SiGe layer.
Claim 20
Dependent Claim
24 words
The method of forming a strained silicon-on-SiGe device according to claim 16 , wherein said oxidation selectivity between SiGe and silicon is approximately 100:1.
Claim 21
Dependent Claim
31 words
The method of forming a strained silicon-on-SiGe device according to claim 16 , wherein said wet oxidation produces oxide encroachment of approximately between 0.2 μm and 0.4 μm under strained-silicon layer.
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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) | 2008-01-25 | 2008-07-26 | 2009-01-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2012-01-25 | 2012-07-26 | 2013-01-25 | $3760.00 | Window Closed / Lapsed |
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