US 5,932,897 AGranted

High-breakdown-voltage semiconductor device

AssigneeKabushiki Kaisha Toshiba

InventorsYusuke Kawaguchi, Akio Nakagawa, Kozo Kinoshita

Life of this patent

Estimating the term…

Loading patent…

Abstract

A high-breakdown-voltage semiconductor device has a first offset layer and a second offset layer the dosage of which is higher than that of the first offset layer. When the gate is in the ON state, the first offset layer functions as a resurf layer. When the gate is in the OFF state, part of the charge in the first offset layer is neutralized by a drain current flowing through an element having a low ON-resistance, however, the second offset layer functions as a resurf layer. When the drain current is Acm.sup.-1 !, the amount of charge of electrons is qC!, and the drift speed of carriers is .upsilon..sub.drift cms.sup.-1 !, the dosage n.sub.2 of the second offset layer is given by n.sub.2 .gtoreq.I.sub.D /(q.upsilon..sub.drift)cms.sup.-2 !.

Claims18

Dependent claims

A high-breakdown-voltage semiconductor device comprising:

a semiconductor substrate;
a body layer of a first conductivity type selectively formed on a region of a surface of the semiconductor substrate;
a source layer of a second conductivity type selectively formed in a surface of the body layer;
a first offset layer of the second conductivity type selectively formed on a region of the surface of the semiconductor substrate which differs from the region of the surface of the semiconductor substrate on which the body layer is formed;
a second offset layer of the second conductivity type formed on at least a surface portion of the first offset layer;
a drain layer of the second conductivity type selectively formed in a surface of the second offset layer;
a source electrode formed to contact a surface of the body layer and a surface of the source layer;
a drain electrode formed on a surface of the drain layer;
an insulating film formed on a region of the semiconductor substrate which is located between the source electrode and the drain electrode;
and
a gate electrode formed on at least that region of the body layer which is located between the source layer and the first offset layer, with the insulating film interposed between the gate electrode and the region of the body layer,
wherein when mobility of carriers in a channel of an element is .mu. cm.sup.2 V.sup.-1 s.sup.-1 !, a dielectric constant of the gate insulating film is .epsilon.F cm.sup.-1 !, a thickness of the gate insulating film is dcm!, a channel length is Lcm!, a threshold voltage is V.sub.T V!, and a rated gate voltage is V.sub.G V!, a drain current I.sub.D per 1 cm of a channel width is given by:
I.sub.D =(.mu..multidot..epsilon.).multidot.(V.sub.G /2-V.sub.T)/(4 Ld)
and when an amount of charge of electrons is qC!, and a drift speed of carriers is .upsilon..sub.drift cm s.sup.-1 !, a dosage n.sub.2 of the second offset layer is expressed by the following formula:
n.sub.2 .gtoreq.I.sub.D /(q.multidot..upsilon..sub.drift)cm.sup.-2 !.

12 more elements

A high-breakdown-voltage semiconductor device comprising:

a semiconductor substrate;
a body layer of a first conductivity type selectively formed on a region of a surface of the semiconductor substrate;
a source layer of a second conductivity type selectively formed in a surface of the body layer;
a first offset layer of the second conductivity type selectively formed on a region of the surface of the semiconductor substrate which differs from the region of the surface of the semiconductor substrate on which the body layer is formed;
a second offset layer of the second conductivity type formed on at least a surface portion of the first offset layer;
a drain layer of the second conductivity type selectively formed in a surface of the second offset layer;
a source electrode formed to contact a surface of the body layer and a surface of the source layer;
a drain electrode formed on a surface of the drain layer;
an insulating film formed on a region of the semiconductor substrate which is located between the source electrode and the drain electrode;
and
a gate electrode formed on a region of the body layer which is located between the source layer and the first offset layer, with the insulating film interposed between the gate electrode and the region of the body layer,
wherein when a dosage of the first offset layer is n.sub.1, and a dosage of the second offset layer is n.sub.2, the following relationship is satisfied:
2n.sub.1 .ltoreq.n.sub.2 .ltoreq.4n.sub.1.

10 more elements

A high-breakdown-voltage semiconductor device comprising:

a semiconductor substrate;
a body layer of a first conductivity type selectively formed on a region of a surface of the semiconductor substrate;
a source layer of a second conductivity type selectively formed in a surface of the body layer;
a first offset layer of the second conductivity type selectively formed on a region of the surface of the semiconductor substrate which differs from the region of the surface of the semiconductor substrate on which the body layer is formed;
a second offset layer of the second conductivity type formed on at least a surface portion of the first offset layer;
a drain layer of the second conductivity type selectively formed in a surface of the second offset layer;
a source electrode formed to contact a surface of the body layer and a surface of the source layer;
a drain electrode formed on a surface of the drain layer;
an insulating film formed on a region of the semiconductor substrate which is located between the source electrode and the drain electrode;
and
a gate electrode formed on a region of the body layer which is located between the source layer and the first offset layer, with the insulating film interposed between the gate electrode and the region of the body layer,
wherein:
a breakdown voltage of the semiconductor device is determined by a state of a depletion layer, which is formed in the first offset layer, when a reverse voltage is applied between the drain layer and the body layer, and a voltage of 0 V is applied to the gate electrode;
and
the breakdown voltage of the semiconductor device is determined by a state of a depletion layer which is formed in the second offset layer when a reverse voltage is applied between the drain layer and the body layer, and a gate voltage having the same polarity as a drain voltage to be applied to the drain electrode is applied to the gate electrode.

12 more elements

Dependencies are inferred from the claim text.