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US5409848A
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US
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Angled lateral pocket implants on p-type semiconductor devices
Assignee: Adeia Semiconductor Technologies LLC
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Filing: 1994-03-31
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Granted: 1995-04-25
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Expires: 2014-03-31
Abstract
Abstract The punchthrough capacity of a p-type semiconductor device is significantly improved by nonuniformly doping the p-channel with n-type implants such as phosphorus. The n-type dopants are implanted at large angles to form pocket implants within the channel region. The dose of the implants, angle of the implants and the thermal cycle annealing of the implants will be optimized for maximum punchthrough capability without substantially detracting from the performance of the semiconductor device.
Inventors
- 👤 Yu-Pin Han
- 👤 Samuel J. S. Nagalingam
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 10:07
CPC Classifications
H; H10; H10D; H10D30/00; H10D30/01; H10D30/021; H10D30/0223; H10D62/00; H10D62/10; H10D62/17; H10D62/213; H10D62/221; H10D62/235; H10D62/299; H10D62/307; H10D62/351; H10D62/357; H10D62/364; H10D62/371; H10P; H10P30/00; H10P30/20; H10P30/222; Y; Y10; Y10S; Y10S148/00; Y10S148/018
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
171 words
A method for nonuniformly doping a channel region in a p-type MOSFET comprising the steps of: (A) providing an n-type semiconductor substrate; (B) forming a gate insulating film on said substrate; (C) forming a conductive layer upon said gate insulating film, which forms the gate electrode; (D) doping the entire source and drain regions of said substrate with a p-type dopant to a first impurity concentration, which is self-aligned to the gate electrode; (E) doping said substrate with an n-type dopant to form first and second pockets containing n-type dopant and having a second impurity concentration that is lower than said first impurity concentration, wherein said n-type dopant is implanted at an angle greater than 0° from a line drawn perpendicular to the surface of said substrate and wherein said first pocket is beneath the gate insulating layer and adjacent to the source region and said second pocket is beneath the gate insulating layer and adjacent to the drain region; and (F) thermally treating said substrate to electrically activate said dopants.
Claim 2
Independent Claim
171 words
A method for nonuniformly doping a channel region in a p-type MOSFET comprising the steps of: (A) providing an n-type semiconductor substrate; (B) forming a gate insulating film on said substrate; (C) forming a conductive layer upon said gate insulating film, which forms the gate electrode; (D) doping the entire source and drain regions of said substrate with a p-type dopant to a first impurity concentration, which is self-aligned to the gate electrode; (E) doping said substrate with an n-type dopant to form first and second pockets containing n-type dopant and having a second impurity concentration that is lower than said first impurity concentration, wherein said n-type dopant is implanted at an angle greater than 0° from a line drawn perpendicular to the surface of said substrate and wherein said first pocket is beneath the gate insulating layer and adjacent to the source region and said second pocket is beneath the gate insulating layer and adjacent to the drain region; and (F) thermally treating said substrate to electrically activate said dopants.
Claim 3
Dependent Claim
13 words
The method of claim 1, wherein said n-type dopant is arsenic or phosphorus.
Claim 4
Dependent Claim
11 words
The method of claim 1, wherein said p-type dopant is boron.
Claim 5
Dependent Claim
48 words
The method according to claim 1, wherein the steps of doping with the p-type dopant and doping with the n-type dopant are effected in order to reduce punchthrough susceptibility of the p-type MOSFET and wherein the p-type MOSFET has a threshold voltage of about -0.5 to -0.9 V.
Claim 6
Dependent Claim
23 words
The method according to claim 4, wherein said p-type dopant is implanted at a dosage greater than about 10 16 atoms/cm 2 .
Claim 7
Dependent Claim
23 words
The method according to claim 4, wherein said p-type dopant is implanted at a dosage greater than about 10 17 atoms/cm 2 .
Claim 8
Dependent Claim
21 words
The method according to claim 6, wherein said first impurity concentration ranges from about 10 18 -10 21 atoms/cm 3 .
Claim 9
Dependent Claim
26 words
The method according to claim 4, wherein said n-type dopant is implanted at a dosage from about 10 12 to about 10 14 atoms/cm 2 .
Claim 10
Dependent Claim
20 words
The method according to claim 8, wherein said second impurity concentration is less than about 10 18 atoms/cm 3 .
Claim 11
Dependent Claim
23 words
The method according to claim 1, wherein said angle at which said n-type dopant is implanted ranges from about 5° to about 75°.
Claim 12
Dependent Claim
26 words
The method according to claim 10, wherein said step of thermally treating said substrate is performed at a temperature which is less than about 950° C.
Claim 13
Dependent Claim
36 words
The method according to claim 1, wherein said thermal treatment is conducted at a temperature that activates said dopants but the temperature is not high enough to cause any significant drive or migration of said dopants.
Claim 14
Dependent Claim
15 words
The method according to claim 12, wherein said temperature is less than about 900° C.
Claim 15
Dependent Claim
26 words
The method according m claim 1, wherein said step of thermally treating said substrate is performed at a temperature which is less than about 1000° C.
Claim 16
Dependent Claim
22 words
The method of claim 1 wherein said p-type dopant is implanted at a dosage greater than about 10 17 atoms/cm 2 .
Claim 17
Dependent Claim
26 words
The method according to claim 15 wherein said n-type dopant is implanted at a dosage from about 10 12 to about 10 14 atoms/cm 2 .
Claim 18
Dependent Claim
15 words
The method according to claim 16 wherein said temperature is less than about 900° C.
Claim 19
Dependent Claim
21 words
The method according to claim 1 wherein said first impurity concentration ranges from about 10 18 -10 21 atoms/cm 3 .
Claim 20
Dependent Claim
20 words
The method according to claim 18 wherein said second impurity concentration is less than about 10 18 atoms/cm 3 .
Claim 21
Dependent Claim
15 words
The method according to claim 19 wherein said temperature is less than about 900° C.
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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) | 1998-04-24 | 1998-10-24 | 1999-04-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-04-24 | 2002-10-24 | 2003-04-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-04-24 | 2006-10-24 | 2007-04-25 | $7700.00 | Window Closed / Lapsed |