US5420451A
Expired / Lapsed
US
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Bidirectional blocking lateral MOSFET with improved on-resistance
Assignee: Vishay Siliconix Inc
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Filing: 1993-11-30
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Granted: 1995-05-30
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Expires: 2013-11-30
Abstract
Abstract A bidirectional current blocking lateral power MOSFET including a source and a drain which are not shorted to a substrate, and voltages that are applied to the source and drain are both higher than the voltage at which the body is maintained (for an N-channel MOSFET) or lower than the voltage at which the body is maintained (for a P-channel MOSFET). The on-resistance of the MOSFET is improved by decreasing the conductance of the epi region and disposing a thin threshold adjust layer on the surface of the substrate between the source and drain regions. An optional second punchthrough preventing implant is disposed on the substrate surface.
Inventors
- 👤 Richard K. Williams
- 👤 Kevin Jew
- 👤 Jun W. Chen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 10:47
CPC Classifications
H; H10; H10D; H10D30/00; H10D30/60; H10D62/00; H10D62/10; H10D62/17; H10D62/351; H10D62/357; H10D62/364; H10D62/378; Y; Y10; Y10S; Y10S148/00; Y10S148/126
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
175 words
A bidirectional current blocking power MOSFET for connecting to a first voltage source providing a first voltage at a level greater than or equal to ground and a second voltage source providing a second voltage at a level greater than or equal to ground, the power MOSFET comprising: a semiconductor substrate; a first N region and a second N region formed in said substrate for connecting to first and second voltage sources, respectively; a P+ body region formed in said substrate, said P+ body region being connected to ground; a P- epitaxial region formed in said substrate above the P+ body region, said P- epitaxial region comprising a channel region located between said first and second N regions; a P threshold adjust layer disposed in said P- epitaxial region between the first and second N regions; an oxide layer formed over the channel region and the first and second N regions; and a gate formed on the oxide layer; wherein neither of said first and second N regions is shorted to said P+ body region.
Claim 2
Dependent Claim
175 words
A bidirectional current blocking power MOSFET for connecting to a first voltage source providing a first voltage at a level greater than or equal to ground and a second voltage source providing a second voltage at a level greater than or equal to ground, the power MOSFET comprising: a semiconductor substrate; a first N region and a second N region formed in said substrate for connecting to first and second voltage sources, respectively; a P+ body region formed in said substrate, said P+ body region being connected to ground; a P- epitaxial region formed in said substrate above the P+ body region, said P- epitaxial region comprising a channel region located between said first and second N regions; a P threshold adjust layer disposed in said P- epitaxial region between the first and second N regions; an oxide layer formed over the channel region and the first and second N regions; and a gate formed on the oxide layer; wherein neither of said first and second N regions is shorted to said P+ body region.
Claim 3
Dependent Claim
57 words
The bidirectional current blocking power MOSFET of claim 1 wherein the P- epitaxial region has a first doping concentration level, the P+ body region has a second doping concentration level, and the P threshold adjust layer has a third doping concentration level, wherein the third doping concentration level is between the first and second doping concentration levels.
Claim 4
Dependent Claim
50 words
The bidirectional current blocking power MOSFET of claim 2 wherein the P threshold adjust layer comprises a threshold adjust implant having a fourth doping concentration level, and a punchthrough implant having a fifth doping concentration level, wherein the fourth doping concentration level is greater than the fifth doping concentration level.
Claim 5
Dependent Claim
46 words
The bidirectional current blocking power MOSFET of claim 3 wherein the threshold adjust implant is formed to a first depth into the substrate, and the punchthrough implant is formed to a second depth into the substrate, wherein the second depth is greater than the first depth.
Claim 6
Dependent Claim
55 words
The bidirectional current blocking power MOSFET of claim 1 wherein the MOSFET is activated by a gate drive voltage applied between the gate and one of the first N region and the second N region, and wherein the oxide layer is formed to a minimum thickness necessary to support the gate drive voltage without breakdown.
Claim 7
Dependent Claim
55 words
The bidirectional current blocking power MOSFET of claim 4 wherein the MOSFET is activated by a gate drive voltage applied between the gate and one of the first N region and the second N region, and wherein the oxide layer is formed to a minimum thickness necessary to support the gate drive voltage without breakdown.
Claim 8
Dependent Claim
26 words
The bidirectional current blocking power MOSFET of claim 1 further comprising a first N- drift region in said P- epitaxial region adjacent said first N region.
Claim 9
Dependent Claim
26 words
The bidirectional current blocking power MOSFET of claim 7 further comprising a second N- drift region in said P- epitaxial region adjacent said second N region.
Claim 10
Dependent Claim
26 words
The bidirectional current blocking power MOSFET of claim 7 wherein said first N- drift region has a length L D of from 1 to 4 μm.
Claim 11
Dependent Claim
22 words
The bidirectional current blocking power MOSFET of claim 1 wherein said gate has a length Lg of from 1 to 4 μm.
Claim 12
Dependent Claim
28 words
The bidirectional current blocking power MOSFET of claim 1 wherein said MOSFET is for blocking a voltage of from 18 to 24 volts when in an off condition.
Claim 13
Dependent Claim
32 words
The bidirectional current blocking power MOSFET of claim 5 wherein the oxide layer is formed to a minimum thickness necessary to support a gate drive voltage of from 4 to 15 volts.
References Cited (Backward Citations)
US4315781A
Cited
US5362981A
Cited
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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) | 1998-05-29 | 1998-11-28 | 1999-05-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-05-29 | 2002-11-28 | 2003-05-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-05-29 | 2006-11-28 | 2007-05-30 | $7700.00 | Window Closed / Lapsed |