US4987459A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Variable capacitance diode element having wide capacitance variation range
Assignee: Asahi Kasei Toko Power Devices Corp
•
Filing: 1990-01-17
•
Granted: 1991-01-22
•
Expires: 2010-01-17
Abstract
Abstract A variable-capacitance diode element having a wide capacitance variation range is disclosed which comprises an epitaxial layer of a first conductivity type which is provided on a semiconductor substrate of the first conductivity type; a diffusion layer of the first conductivity type which is formed in the epitaxial layer with a higher concentration than said epitaxial layer by means of ion implantation; at least one diffusion layer of a second conductivity type which is formed in the diffusion layer of the first conductivity type so as to define PN junction; and a first-conductivity type buried layer of a low resistivity which is formed the boundary portion between the semiconductor substrate and the epitaxial layer where a depletion layer reaches which occurs in response to a reverse bias voltage being applied to the PN junction, whereby the depletion layer is caused to extend to a maximum possible effect.
Inventors
- 👤 Takeshi Kasahara
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 07:46
CPC Classifications
H; H10; H10D; H10D1/00; H10D1/60; H10D1/62; H10D1/64; Y; Y10; Y10S; Y10S148/00; Y10S148/004; Y10S257/00; Y10S257/913
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
150 words
A variable-capacitance diode element, comprising: an epitaxial layer provided on a semiconductor substrate of a first conductivity type, said epitaxial layer having the first conductivity type and relatively a lower resistivity than that of said semiconductor substrate; a first diffusion layer formed in said epitaxial layer, said first diffusion layer having the first conductivity type and a higher impurity concentration than that of said epitaxial layer; at least one second diffusion layer of a second conductivity type which is formed in said first diffusion layer so that PN junction is defined between said first and second diffusion layers; and a buried layer formed in boundary portion between said semiconductor substrate and said epitaxial layer where a depletion layer which occurs due to a reverse bias voltage being applied to said PN junction reaches, said buried layer having the first conductivity and a lower resistivity than that of said semiconductor substrate.
Claim 2
Dependent Claim
150 words
A variable-capacitance diode element, comprising: an epitaxial layer provided on a semiconductor substrate of a first conductivity type, said epitaxial layer having the first conductivity type and relatively a lower resistivity than that of said semiconductor substrate; a first diffusion layer formed in said epitaxial layer, said first diffusion layer having the first conductivity type and a higher impurity concentration than that of said epitaxial layer; at least one second diffusion layer of a second conductivity type which is formed in said first diffusion layer so that PN junction is defined between said first and second diffusion layers; and a buried layer formed in boundary portion between said semiconductor substrate and said epitaxial layer where a depletion layer which occurs due to a reverse bias voltage being applied to said PN junction reaches, said buried layer having the first conductivity and a lower resistivity than that of said semiconductor substrate.
Claim 3
Dependent Claim
66 words
A variable-capacitance diode element according to claim 1, wherein said second diffusion layer is provided in a two-layer form, one of the two layers being formed in said first diffusion layer, the other one of said two layers covering an exposed portion of a major surface of said first diffusion layer and an exposed portion of a major surface of said one of the two layers.
Claim 4
Dependent Claim
132 words
A variable-capacitance diode element, comprising: an epitaxial layer provided on a semiconductor substrate of a first conductivity type, said epitaxial layer having said first conductivity type and a relatively lower resistivity than that of said semiconductor substrate; a diffusion of the first conductivity type which is formed in said epitaxial layer and has a higher impurity concentration than that of said epitaxial layer; at least one diffusion layer of a second conductivity type which is formed in said first conductivity type diffusion layer; and a buried layer of the first conductivity type which is formed in a boundary portion between said semiconductor substrate and said epitaxial layer peripherally thereof and except immediately below said first conductivity type diffusion layer, said buried layer having a lower resistivity than that of said semiconductor substrate.
Claim 5
Dependent Claim
132 words
A variable-capacitance diode element, comprising: an epitaxial layer provided on a semiconductor substrate of a first conductivity type, said epitaxial layer having said first conductivity type and a relatively lower resistivity than that of said semiconductor substrate; a diffusion of the first conductivity type which is formed in said epitaxial layer and has a higher impurity concentration than that of said epitaxial layer; at least one diffusion layer of a second conductivity type which is formed in said first conductivity type diffusion layer; and a buried layer of the first conductivity type which is formed in a boundary portion between said semiconductor substrate and said epitaxial layer peripherally thereof and except immediately below said first conductivity type diffusion layer, said buried layer having a lower resistivity than that of said semiconductor substrate.
Claim 6
Dependent Claim
72 words
A variable-capacitance diode element according to claim 3, wherein said second conductivity type diffusion layer is provided in a two-layer form, one of the two layers being formed in said first conductivity type diffusion layer, the other one of said two layers covering an exposed portion of a major surface of said first conductivity type diffusion layer and an exposed portion of a major surface of said one of the two layers.
Claim 7
Dependent Claim
153 words
A variable-capacitance diode element comprising: an epitaxial layer provided on a semiconductor substrate of a first conductivity type, said epitaxial layer having the first conductivity type and a relatively lower resistivity than that of said semiconductor substrate; a first diffusion layer of the first conductivity type which is provided in said epitaxial layer in a superimposed multi-layer form, said first diffusion layer having a higher impurity concentration than that of said epitaxial layer; a second diffusion layer of a second conductivity type which is formed in said first diffusion layer so that PN junction is defined therebetween; and a buried layer of the first conductivity type which is provided in a boundary portion between said semiconductor substrate and said epitaxial layer where a depletion layer which occurs due to a reverse bias voltage being applied to said PN junction reaches, said buried layer having a lower resistivity than that of said semiconductor substrate.
Claim 8
Dependent Claim
153 words
A variable-capacitance diode element comprising: an epitaxial layer provided on a semiconductor substrate of a first conductivity type, said epitaxial layer having the first conductivity type and a relatively lower resistivity than that of said semiconductor substrate; a first diffusion layer of the first conductivity type which is provided in said epitaxial layer in a superimposed multi-layer form, said first diffusion layer having a higher impurity concentration than that of said epitaxial layer; a second diffusion layer of a second conductivity type which is formed in said first diffusion layer so that PN junction is defined therebetween; and a buried layer of the first conductivity type which is provided in a boundary portion between said semiconductor substrate and said epitaxial layer where a depletion layer which occurs due to a reverse bias voltage being applied to said PN junction reaches, said buried layer having a lower resistivity than that of said semiconductor substrate.
References Cited (Backward Citations)
US3646411A
Cited
US3891479A
Cited
US3909119A
Cited
US4003009A
Cited
US3959809A
Cited
US4106953A
Cited
JPS53144684A
Cited
JPS5669869A
Cited
JPS5690566A
Cited
JPS5850781A
Cited
JPS62101076A
Cited
JPS63138779A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-01-21 | 1994-07-23 | 1995-01-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-01-21 | 1998-07-23 | 1999-01-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-01-21 | 2002-07-23 | 2003-01-22 | $7700.00 | Window Closed / Lapsed |