US5970353A
Expired / Lapsed
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Reduced channel length lightly doped drain transistor using a sub-amorphous large tilt angle implant to provide enhanced lateral diffusion
Assignee: GlobalFoundries Inc
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Filing: 1998-03-30
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Granted: 1999-10-19
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Expires: 2018-03-30
Abstract
Abstract A method of reducing an effective channel length of a lightly doped drain transistor (50), includes the steps of forming a gate electrode (52) and a gate oxide (54) over a semiconductor substrate (56) and implanting a drain region (58) of the substrate (56) with a sub-amorphous large tilt angle implant to thereby supply interstitials (62) at a location under the gate oxide (54). The method also includes forming a lightly doped drain extension region (66) in the drain region (58) of the substrate (56) and forming a drain (70) in the drain region (58) and forming a source extension region (67) and a source (72) in a source region (60) of the substrate (56). Lastly, the method includes thermally treating the substrate (56), wherein the interstitials (62) enhance a lateral diffusion (84) under the gate oxide (54) without substantially impacting a vertical diffusion (86) of the extension regions (66, 67), thereby reducing the effective channel length without an increase in a junction depth of the drain (70) and the drain extension region (66) or the source (72) and the source extension region (67).
Inventors
- 👤 Akif Sultan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 23:00
CPC Classifications
H; H10; H10D; H10D30/00; H10D30/01; H10D30/021; H10D30/0223; H10D30/0227; H10P; H10P10/00; H10D30/60; H10D30/601; H10D30/605; H10D64/00; H10D64/01; H10D64/021; H10P30/00; H10P30/20; H10P30/202; H10P30/204; H10P30/208; H10P30/21; H10P30/222; H10P30/225; H10P30/28
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
143 words
A method of reducing an effective channel length of a lightly doped drain transistor, comprising the steps of: forming a gate electrode and a gate oxide over a semiconductor substrate; implanting a region of the substrate where a drain is formed with a large tilt angle implant which supplies interstitials at a location under the gate oxide; forming a lightly doped drain extension region in the region of the substrate where the drain is formed; forming a drain in the region where the drain is formed and a source in a source region of the substrate; and thermally treating the substrate, wherein the interstitials enhance a lateral diffusion under the gate oxide without substantially impacting a vertical diffusion of the extension region, thereby reducing the effective channel length without an increase in a junction depth of the drain and the drain extension region.
Claim 2
Independent Claim
143 words
A method of reducing an effective channel length of a lightly doped drain transistor, comprising the steps of: forming a gate electrode and a gate oxide over a semiconductor substrate; implanting a region of the substrate where a drain is formed with a large tilt angle implant which supplies interstitials at a location under the gate oxide; forming a lightly doped drain extension region in the region of the substrate where the drain is formed; forming a drain in the region where the drain is formed and a source in a source region of the substrate; and thermally treating the substrate, wherein the interstitials enhance a lateral diffusion under the gate oxide without substantially impacting a vertical diffusion of the extension region, thereby reducing the effective channel length without an increase in a junction depth of the drain and the drain extension region.
Claim 3
Dependent Claim
16 words
The method of claim 1, wherein the tilt angle is in the range of about 30-60°.
Claim 4
Dependent Claim
34 words
The method of claim 1, wherein the step of implanting the region where the drain is formed with the large tilt angle implant precedes the step of forming the lightly doped drain extension region.
Claim 5
Dependent Claim
31 words
The method of claim 1, wherein the step of implanting the region where the drain is formed with the large tilt angle implant comprises implanting one of silicon, germanium or indium.
Claim 6
Independent Claim
170 words
A method of reducing an effective channel length of a lightly doped drain transistor, comprising the steps of: forming a gate electrode and a gate oxide over a semiconductor substrate; implanting a region of the substrate where a drain is formed with a large tilt angle implant which supplies interstitials at a location under the gate oxide, wherein the step of implanting the region where the drain is formed with the large tilt angle implant comprises implanting a sub-amorphous dose into the drain region; forming a lightly doped drain extension region in the region of the substrate where the drain is formed; forming a drain in the region where the drain is formed and a source in a source region of the substrate; and thermally treating the substrate, wherein the interstitials enhance a lateral diffusion under the gate oxide without substantially impacting a vertical diffusion of the extension region, thereby reducing the effective channel length without an increase in a junction depth of the drain and the drain extension region.
Claim 7
Independent Claim
170 words
A method of reducing an effective channel length of a lightly doped drain transistor, comprising the steps of: forming a gate electrode and a gate oxide over a semiconductor substrate; implanting a region of the substrate where a drain is formed with a large tilt angle implant which supplies interstitials at a location under the gate oxide, wherein the step of implanting the region where the drain is formed with the large tilt angle implant comprises implanting a sub-amorphous dose into the drain region; forming a lightly doped drain extension region in the region of the substrate where the drain is formed; forming a drain in the region where the drain is formed and a source in a source region of the substrate; and thermally treating the substrate, wherein the interstitials enhance a lateral diffusion under the gate oxide without substantially impacting a vertical diffusion of the extension region, thereby reducing the effective channel length without an increase in a junction depth of the drain and the drain extension region.
Claim 8
Independent Claim
160 words
A method of reducing an effective channel length of a lightly doped drain transistor, comprising the steps of: forming a gate electrode and a gate oxide over a semiconductor substrate; implanting a region of the substrate where a drain is formed with a large tilt angle implant which supplies interstitials at a location under the gate oxide, wherein a dose of the large tilt angle implant is about 10-30 percent of an amorphizing dose; forming a lightly doped drain extension region in the region of the substrate where the drain is formed; forming a drain in the region where the drain is formed and a source in a source region of the substrate; and thermally treating the substrate, wherein the interstitials enhance a lateral diffusion under the gate oxide without substantially impacting a vertical diffusion of the extension region, thereby reducing the effective channel length without an increase in a junction depth of the drain and the drain extension region.
Claim 9
Independent Claim
160 words
A method of reducing an effective channel length of a lightly doped drain transistor, comprising the steps of: forming a gate electrode and a gate oxide over a semiconductor substrate; implanting a region of the substrate where a drain is formed with a large tilt angle implant which supplies interstitials at a location under the gate oxide, wherein a dose of the large tilt angle implant is about 10-30 percent of an amorphizing dose; forming a lightly doped drain extension region in the region of the substrate where the drain is formed; forming a drain in the region where the drain is formed and a source in a source region of the substrate; and thermally treating the substrate, wherein the interstitials enhance a lateral diffusion under the gate oxide without substantially impacting a vertical diffusion of the extension region, thereby reducing the effective channel length without an increase in a junction depth of the drain and the drain extension region.
Claim 10
Dependent Claim
19 words
The method of claim 1, wherein the step of thermally treating the substrate comprises performing a rapid thermal anneal.
Claim 11
Dependent Claim
57 words
The method of claim 1, wherein a composite doping profile and interstitial profile under the gate oxide comprises a large concentration gradient along a lateral edge of the drain extension region and a substantially smaller concentration gradient along a bottom portion of the drain extension region, thereby resulting in an enhanced lateral diffusion under the gate oxide.
Claim 12
Independent Claim
210 words
A method of reducing an effective channel length of a lightly doped drain transistor, comprising the steps of: forming a gate electrode and a gate oxide over a semiconductor substrate; implanting a region of the substrate where a drain is formed with a large tilt angle implant which supplies interstitials at a location under the gate oxide; forming a lightly doped drain extension region in the region of the substrate where the drain is formed; forming a drain in the region where the drain is formed and a source in a source region of the substrate; and thermally treating the substrate, wherein the interstitials enhance a lateral diffusion under the gate oxide without substantially impacting a vertical diffusion of the extension region, thereby reducing the effective channel length without an increase in a junction depth of the drain and the drain extension region, further comprising the step of forming a first sidewall spacer on a drain side of the gate and the gate oxide before the implanting of the region where the drain is formed with the large tilt angle implant, wherein a thickness of the first sidewall spacer controls the location of dopants under the gate oxide, thereby allowing the reduce channel length of the transistor to be customized.
Claim 13
Independent Claim
210 words
A method of reducing an effective channel length of a lightly doped drain transistor, comprising the steps of: forming a gate electrode and a gate oxide over a semiconductor substrate; implanting a region of the substrate where a drain is formed with a large tilt angle implant which supplies interstitials at a location under the gate oxide; forming a lightly doped drain extension region in the region of the substrate where the drain is formed; forming a drain in the region where the drain is formed and a source in a source region of the substrate; and thermally treating the substrate, wherein the interstitials enhance a lateral diffusion under the gate oxide without substantially impacting a vertical diffusion of the extension region, thereby reducing the effective channel length without an increase in a junction depth of the drain and the drain extension region, further comprising the step of forming a first sidewall spacer on a drain side of the gate and the gate oxide before the implanting of the region where the drain is formed with the large tilt angle implant, wherein a thickness of the first sidewall spacer controls the location of dopants under the gate oxide, thereby allowing the reduce channel length of the transistor to be customized.
Claim 14
Dependent Claim
52 words
The method of claim 9, further comprising the step of forming a second sidewall spacer adjacent to the first sidewall spacer before the forming of the drain, wherein the drain region and the drain extension region overlap and the second sidewall spacer laterally staggers the drain region and the drain extension region.
Claim 15
Dependent Claim
37 words
The method of claim 1, further comprising the step of implanting the source region of the substrate with the large tilt angle implant, thereby supplying interstitials at a location in the source region under the gate oxide.
Claim 16
Dependent Claim
21 words
The method of claim 1, wherein implanting the drain region with the large tilt angle implant comprises performing a quad implant.
Claim 17
Dependent Claim
36 words
The method of claim 1, further comprising the step of forming a lightly doped source extension region in the source region of the substrate at the same time the lightly doped drain extension region is formed.
Claim 18
Independent Claim
140 words
A method of forming a transistor, comprising the steps of: forming a gate electrode and a gate oxide over a semiconductor substrate; supplying interstitials in at least one of a region of the substrate where a drain is formed and a region of the substrate where a source is formed; forming an extension region in the at least one of the region where the drain is formed and the region where the source is formed; forming a drain in the region where the drain is formed and a source in a region where the source is formed; and thermally treating the substrate, wherein the interstitials enhance a lateral diffusion under the gate oxide without substantially impacting a vertical diffusion of the extension region, thereby reducing the effective channel length without an increase in a junction depth of the extension region.
Claim 19
Independent Claim
140 words
A method of forming a transistor, comprising the steps of: forming a gate electrode and a gate oxide over a semiconductor substrate; supplying interstitials in at least one of a region of the substrate where a drain is formed and a region of the substrate where a source is formed; forming an extension region in the at least one of the region where the drain is formed and the region where the source is formed; forming a drain in the region where the drain is formed and a source in a region where the source is formed; and thermally treating the substrate, wherein the interstitials enhance a lateral diffusion under the gate oxide without substantially impacting a vertical diffusion of the extension region, thereby reducing the effective channel length without an increase in a junction depth of the extension region.
Claim 20
Dependent Claim
51 words
The method of claim 14, wherein the step of supplying interstitials comprises the step of implanting at least one of the region where the drain is formed and the region where the source is formed with a large tilt angle implant, thereby supplying interstitials at a location under the gate oxide.
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| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 2002-10-18 | 2003-04-19 | 2003-10-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2006-10-18 | 2007-04-19 | 2007-10-19 | $3760.00 | Window Closed / Lapsed |
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