US5637902A
Expired / Lapsed
US
⏱️ 0.0 years remaining
N-well resistor as a ballast resistor for output MOSFET
Assignee: NXP BV
•
Filing: 1996-01-16
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Granted: 1997-06-10
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Expires: 2016-01-16
Abstract
Abstract A resistor formed in a well adjacent to a transistor serves as a ballast resistor for the transistor. The transistor is formed in a first region on a substrate. The first region is of a first conductivity type. A well of second conductivity type is formed adjacent to the first region. A gate region is formed over a portion of the first region. Concurrently, a covering is formed over a first area of the well. The covering and the gate region are comprised of the same material. Source/drain regions of the second conductivity type are formed on either side of the gate region. The source/drain regions are of the first conductivity type. A first source/drain region extends into the well. Concurrent to the forming of the source drain regions, a doped region is formed within the well. The doped region and the first source/drain region have the same doping density. The doped region is physically separated from the first source/drain region by the first area of the well. Contact regions for the transistor are formed within the second source/drain region and within the doped region.
Inventors
- 👤 Chun Jiang
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 08:21
CPC Classifications
H; H10; H10D; H10D89/00; H10D89/60; H10D89/601; H10D89/911
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
161 words
A transistor comprising: a gate region; a channel region of a first conductivity type, the channel region being located under the gate region and separated from the gate region by an insulator region; a first source/drain region located on a first side of the channel region, the first source/drain region being of a second conductivity type; a second source/drain region located on a second side of the channel region, the second source/drain region being of the second conductivity type; a well of the second conductivity type, the first source/drain region extending into the well; and, a doped region within the well, the doped region being of a same doping density as a doping density of the first source/drain region, the doped region being physically separate from the first source/drain region by a first area of the well; wherein the first area of the well is covered by a first material of a same composition as a material composing the gate region.
Claim 2
Dependent Claim
161 words
A transistor comprising: a gate region; a channel region of a first conductivity type, the channel region being located under the gate region and separated from the gate region by an insulator region; a first source/drain region located on a first side of the channel region, the first source/drain region being of a second conductivity type; a second source/drain region located on a second side of the channel region, the second source/drain region being of the second conductivity type; a well of the second conductivity type, the first source/drain region extending into the well; and, a doped region within the well, the doped region being of a same doping density as a doping density of the first source/drain region, the doped region being physically separate from the first source/drain region by a first area of the well; wherein the first area of the well is covered by a first material of a same composition as a material composing the gate region.
Claim 3
Dependent Claim
12 words
A transistor as in claim 1 wherein the first material comprises polysilicon.
Claim 4
Dependent Claim
21 words
A transistor as in claim 1 wherein contact regions are formed within the second source/drain region and within the doped region.
Claim 5
Dependent Claim
20 words
A transistor as in claim 1 wherein the first conductivity type is P-type and the second conductivity type is N-type.
Claim 6
Dependent Claim
26 words
A transistor as in claim 1 wherein the transistor functions as an electro-static discharge transistor and is connected to an input/output pad of an integrated circuit.
Claim 7
Dependent Claim
109 words
A resistor connected to a first source/drain region of a transistor, the transistor having a channel of a first conductivity type, the resistor comprising: a well of the second conductivity type, the first source/drain region extending into the well; and, a doped region within the well, the doped region being of a same doping density as a doping density of the first source/drain region, the doped region being physically separate from the first source/drain region by a first area of the well; wherein the first area of the well is covered by a first material of a same composition as a material composing a gate region of the transistor.
Claim 8
Dependent Claim
109 words
A resistor connected to a first source/drain region of a transistor, the transistor having a channel of a first conductivity type, the resistor comprising: a well of the second conductivity type, the first source/drain region extending into the well; and, a doped region within the well, the doped region being of a same doping density as a doping density of the first source/drain region, the doped region being physically separate from the first source/drain region by a first area of the well; wherein the first area of the well is covered by a first material of a same composition as a material composing a gate region of the transistor.
Claim 9
Dependent Claim
12 words
A resistor as in claim 6 wherein the first material comprises polysilicon.
Claim 10
Dependent Claim
24 words
A resistor as in claim 6 wherein contact regions are formed within the doped region and within a second source/drain region of the transistor.
Claim 11
Dependent Claim
20 words
A resistor as in claim 6 wherein the first conductivity type is P-type and the second conductivity type is N-type.
References Cited (Backward Citations)
US4937471A
Cited
US5440162A
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) | 2000-06-09 | 2000-12-09 | 2001-06-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-06-09 | 2004-12-09 | 2005-06-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-06-09 | 2008-12-09 | 2009-06-10 | $7700.00 | Window Closed / Lapsed |