Power semiconductor having a lightly doped drift and buffer layer
First Claim
1. A power MOS transistor of the planar type, comprising:
- a semiconductor body having a first and a second surface,body regions of a first conductivity type and a first dopant concentration formed in the first surface;
a highly doped source region of a second conductivity type having a first dopant concentration, provided at the first surface;
a contact arrangement provided at the first surface, the contact arrangement comprising a gate electrode over an insulating layer on the first surface and source electrode, directly over the first surface and in contact with the source region;
at least two deep, lightly doped well regions of the first conductivity type having a second dopant concentration, and having a minimum lateral distance therebetween;
a highly doped drain contact layer of the second conductivity type and a second dopant concentration provided in or on the second surface of the semiconductor body; and
an electrode provided on the free surface of the drain contact layer;
wherein underneath and between the deep well regions of the first conductivity type a lightly doped drift and buffer layer of the second conductivity type and a third dopant concentration is provided, wherein the drift and buffer layer has a minimum vertical extension between the drain contact layer and the bottom of the deepest well region which is at least equal to the minimum lateral distance between the deep well regionswherein the vertical extension of the drift and buffer layer amounts to at least twice the minimum lateral distance between the deep well regions; and
wherein the vertical extension of the drift and buffer layer between the drain contact layer and the bottom of the deepest well region is determined such that a total amount of its dopants per unit area is larger than a breakdown charge amount.
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Abstract
A power semiconductor element having a lightly doped drift and buffer layer is disclosed. One embodiment has, underneath and between deep well regions of a first conductivity type, a lightly doped drift and buffer layer of a second conductivity type. The drift and buffer layer has a minimum vertical extension between a drain contact layer on the adjacent surface of a semiconductor substrate and the bottom of the deepest well region which is at least equal to a minimum lateral distance between the deep well regions. The vertical extension can also be determined such that a total amount of dopant per unit area in the drift and buffer layer is larger than a breakdown charge amount at breakdown voltage.
15 Citations
37 Claims
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1. A power MOS transistor of the planar type, comprising:
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a semiconductor body having a first and a second surface, body regions of a first conductivity type and a first dopant concentration formed in the first surface; a highly doped source region of a second conductivity type having a first dopant concentration, provided at the first surface; a contact arrangement provided at the first surface, the contact arrangement comprising a gate electrode over an insulating layer on the first surface and source electrode, directly over the first surface and in contact with the source region; at least two deep, lightly doped well regions of the first conductivity type having a second dopant concentration, and having a minimum lateral distance therebetween; a highly doped drain contact layer of the second conductivity type and a second dopant concentration provided in or on the second surface of the semiconductor body; and an electrode provided on the free surface of the drain contact layer; wherein underneath and between the deep well regions of the first conductivity type a lightly doped drift and buffer layer of the second conductivity type and a third dopant concentration is provided, wherein the drift and buffer layer has a minimum vertical extension between the drain contact layer and the bottom of the deepest well region which is at least equal to the minimum lateral distance between the deep well regions wherein the vertical extension of the drift and buffer layer amounts to at least twice the minimum lateral distance between the deep well regions; and wherein the vertical extension of the drift and buffer layer between the drain contact layer and the bottom of the deepest well region is determined such that a total amount of its dopants per unit area is larger than a breakdown charge amount. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A super junction power transistor of a trench type, comprising:
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a semiconductor body having a first surface and a second surface; a body region of a first conductivity type and a first dopant concentration formed in the first surface; a source region of a second conductivity type provided at the first surface; a contact arrangement which comprises a source electrode over a first insulating layer on the first surface and in contact with the source region and a gate electrode provided within a trench extending vertically into the first surface of the semiconductor body and being separated from walls of the trench by a second insulating layer; at least two deep well regions of the first conductivity type having a second dopant concentration, the deep well regions having a minimum lateral distance therebetween and having a shallow well region disposed therebetween, and wherein the deep well regions are constituted by a vertical stack of bubble-shaped well regions; a drain contact layer of the second conductivity type provided at the second surface; an electrode provided on a surface of the drain contact layer; and a drift and buffer layer of the second conductivity type and including a third dopant concentration, wherein the drift and buffer layer is provided underneath the deep well regions of the first conductivity type, wherein the drift and buffer layer has a minimum vertical extension between the drain contact layer and a bottom of a deepest well region of the deep well regions and which is at least equal to the minimum lateral distance between the deep well regions. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15)
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16. A super junction power transistor of a trench type, comprising:
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a semiconductor body having a first surface and a second surface; a body region of a first conductivity type and a first dopant concentration formed in the first surface; a source region of a second conductivity type provided at the first surface; a contact arrangement with a trench which extends into the first surface; at least two well regions of the first conductivity type having a second dopant concentration, and having a minimum lateral distance therebetween; a drain contact layer of the second conductivity type provided at the second surface; an electrode provided on a surface of the drain contact layer; and a drift and buffer layer of the second conductivity type and including a third dopant concentration is provided underneath the well regions of the first conductivity type, wherein the drift and buffer layer has a minimum vertical extension between the drain contact layer and a bottom of a deepest well region of the well regions and which is at least equal to the minimum lateral distance between the well regions. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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27. A power semiconductor, comprising:
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a semiconductor body having a first surface and a second surface; a body region of a first conductivity type and a first dopant concentration formed in the first surface; a source region of a second conductivity type provided at the first surface; a contact arrangement provided at the first surface; at least two well regions of the first conductivity type having a second dopant concentration, and having a minimum lateral distance therebetween; a drain contact layer of the second conductivity type provided in or on the second surface of the semiconductor body; an electrode provided on a surface of the drain contact layer; a drift layer of the second conductivity type, wherein the drift layer is provided underneath and between the well regions of the first conductivity type; and a buffer layer of the second conductivity type provided underneath the drift layer, wherein a portion of the drift layer that is provided underneath the well regions combined with the buffer layer have a minimum vertical extension between the drain contact layer and a bottom of a deepest well region of the well regions and which is at least equal to the minimum lateral distance between the well regions, wherein the power semiconductor is a super junction power transistor of a trench type. - View Dependent Claims (28, 29, 30, 31, 32, 33, 34, 35, 36, 37)
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Specification