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US6281559B1
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Gate stack structure for variable threshold voltage
Assignee: Advanced Micro Devices Inc
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Filing: 1999-03-03
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Granted: 2001-08-28
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Expires: 2019-03-03
Abstract
Abstract An ultra-large-scale integrated (ULSI) circuit includes MOSFETs which have different threshold voltages and yet have the same channel characteristics. The MOSFETs include gate structures or gate stacks with a silicon and germanium material provided over a seed layer. The seed layer can be a 20-40 Å polysilicon layer. An amorphous silicon layer is provided over the silicon and germanium material, and a cap layer is provided over the amorphous silicon layer. The polysilicon material is implanted with lower concentrations of germanium, where lower threshold voltage MOSFETs are required. Over a range of 0-60% concentration of germanium, the threshold voltage can be varied by roughly 240 mV.
Inventors
- 👤 Bin Yu
- 👤 Ercan Adem
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 02:31
CPC Classifications
H; H10; H10D; H10D84/00; H10D84/01; H10D84/0123; H10D84/0126; H10D84/0135; H10D84/014; H10D64/00; H10D64/01; H10D64/013; H10D64/01302; H10D64/01304; H10D64/01314; H10D64/60; H10D64/66; H10D64/661; H10D64/662; H10D64/667; H10D84/0165; H10D84/0172; H10D84/0177; H10D84/02; H10D84/03; H10D84/038
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
88 words
A gate stack structure above a single crystal substrate, the gate stack structure comprising: a gate insulating layer above the single crystal substrate; a thin semiconductor seed layer disposed above the gate insulating layer; a compound semiconductor layer including germanium disposed above the thin semiconductor seed layer; an amorphous semiconductor layer above the compound semiconductor layer; and a silicide layer disposed above the amorphous semiconductor layer, the silicide layer being in contact with the amorphous semiconductor layer, the amorphous semiconductor layer being thicker than the compound semiconductor layer.
Claim 2
Dependent Claim
88 words
A gate stack structure above a single crystal substrate, the gate stack structure comprising: a gate insulating layer above the single crystal substrate; a thin semiconductor seed layer disposed above the gate insulating layer; a compound semiconductor layer including germanium disposed above the thin semiconductor seed layer; an amorphous semiconductor layer above the compound semiconductor layer; and a silicide layer disposed above the amorphous semiconductor layer, the silicide layer being in contact with the amorphous semiconductor layer, the amorphous semiconductor layer being thicker than the compound semiconductor layer.
Claim 3
Dependent Claim
21 words
The gate stack structure of claim 1 , wherein the seed layer includes polysilicon deposited by low pressure chemical vapor deposition.
Claim 4
Dependent Claim
14 words
The gate stack structure of claim 1 , wherein the silicide layer includes tungsten.
Claim 5
Dependent Claim
26 words
The gate stack structure of claim 1 , wherein the gate stack is subjected to a rapid thermal anneal to diffuse germanium throughout the gate stack.
Claim 6
Dependent Claim
22 words
The gate stack structure of claim 1 , wherein the gate stack is doped with P-type or N-type dopants to increase conductivity.
Claim 7
Dependent Claim
69 words
An integrated circuit including a plurality of transistors, the transistors including a gate dielectric, a seed layer disposed above the gate dielectric, a compound semiconductor layer disposed above the seed layer, an amorphous layer above the compound layer, and a silicide layer above the amorphous layer, wherein the compound semiconductor layer includes first semiconductor atoms and second semiconductor atoms, the amorphous layer being thicker than the compound semiconductor layer.
Claim 8
Dependent Claim
69 words
An integrated circuit including a plurality of transistors, the transistors including a gate dielectric, a seed layer disposed above the gate dielectric, a compound semiconductor layer disposed above the seed layer, an amorphous layer above the compound layer, and a silicide layer above the amorphous layer, wherein the compound semiconductor layer includes first semiconductor atoms and second semiconductor atoms, the amorphous layer being thicker than the compound semiconductor layer.
Claim 9
Dependent Claim
30 words
The integrated circuit of claim 6 , wherein threshold voltages for the transistors are controlled by a concentration of the first semiconductor atoms with respect to the second semiconductor atoms.
Claim 10
Dependent Claim
15 words
The integrated circuit of claim 6 , wherein the amorphous layer is a silicon layer.
Claim 11
Dependent Claim
19 words
The integrated circuit of claim 8 , wherein the first atoms are silicon and the second atoms are germanium.
Claim 12
Dependent Claim
20 words
The integrated circuit of claim 8 , wherein the transistors further include: a cap layer disposed above the amorphous layer.
Claim 13
Dependent Claim
28 words
The gate stack structure of claim 6 , wherein the seed layer is a 20 to 40 Angstrom thick polysilicon layer deposited by low pressure chemical vapor deposition.
Claim 14
Dependent Claim
15 words
The integrated circuit of claim 10 , wherein the amorphous layer is a silicon layer.
Claim 15
Dependent Claim
80 words
A gate stack for an ultra-large scale integrated circuit, the gate stack comprising: a gate dielectric layer; and a gate conductor above the gate dielectric layer, the gate conductor including a seed layer, an amorphous layer and a compound semiconductor layer, the seed layer being adjacent the compound semiconductor layer, the seed layer being less than 20-40 Å thick, the compound semiconductor layer includes germanium, the amorphous layer is adjacent the compound layer and thicker than the compound semiconductor layer.
Claim 16
Dependent Claim
80 words
A gate stack for an ultra-large scale integrated circuit, the gate stack comprising: a gate dielectric layer; and a gate conductor above the gate dielectric layer, the gate conductor including a seed layer, an amorphous layer and a compound semiconductor layer, the seed layer being adjacent the compound semiconductor layer, the seed layer being less than 20-40 Å thick, the compound semiconductor layer includes germanium, the amorphous layer is adjacent the compound layer and thicker than the compound semiconductor layer.
Claim 17
Dependent Claim
21 words
The gate stack of claim 13 wherein the amorphous layer is at least twice as thick as the compound semiconductor layer.
Claim 18
Dependent Claim
20 words
The gate stack of claim 14 wherein the seed layer, the compound semiconductor layer and the amorphous layer include silicon.
Claim 19
Dependent Claim
19 words
The gate stack of claim 15 wherein the gate conductor further includes a silicide layer adjacent the amorphous layer.
Claim 20
Dependent Claim
17 words
The gate stack of claim 16 further comprising a silicon oxynitride cap layer above the silicide layer.
Claim 21
Dependent Claim
15 words
The gate stack of claim 13 wherein the compound semiconductor layer is 200-400 Å thick.
Claim 22
Dependent Claim
14 words
The gate stack of claim 16 wherein the silicide layer is 100-200 Å thick.
Claim 23
Dependent Claim
14 words
The gate stack of claim 19 wherein the amorphous layer is 500-550 Å thick.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2004-08-27 | 2005-02-26 | 2005-08-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2008-08-27 | 2009-02-26 | 2009-08-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2012-08-27 | 2013-02-26 | 2013-08-28 | $7700.00 | Window Closed / Lapsed |