Kabushiki Kaisha Toshiba

Kozo Kinoshita

Akio Nakagawa

Yusuke Kawaguchi

Wataru Saito

Takashi Shinohe

Ichiro Omura

Tetsuo Hatakeyama

A power semiconductor device is disclosed, which comprises a semiconductor layer including a first semiconductor layer of a first conductivity type and a second semiconductor layer of a second conductivity type, which are periodically formed in the lateral direction, and a power semiconductor element including the semiconductor layers that are formed periodically, wherein a distribution of an amount of an impurity in a vertical direction of the first semiconductor layer differs from a distribution of an amount of an impurity in the vertical direction of the second semiconductor layer.

Semiconductor device with alternating conductivity type layers having different vertical impurity concentration profiles

A high withstand voltage semiconductor device does not show any significant fall of its withstand voltage if the impurity concentration of the RESURF layer of a low impurity concentration semiconductor region thereof varies from the optimal level and/or influenced by the fixed electric charge. The device is produced by forming a ring-shaped high impurity concentration edge termination layer of a second conductivity type and a ring-shaped low impurity concentration RESURF layer of the second conductivity type on the front surface of a semiconductor layer of a first conductivity type carrying electrodes respectively on the opposite surfaces thereof along the outer edge of one of the electrodes, then forming an outer ring layer with an impurity concentration substantially as low as the RESURF layer concentrically outside the RESURF layer with a gap separating therebetween and subsequently forming an inner ring layer with an impurity concentration substantially as high as the edge termination layer concentrically inside the RESURF layer.

High withstand voltage semiconductor device

A high withstand voltage semicnductor device does not show any significant fall of its withstand voltage if the impurity concentration of the RESURF layer of a low impurity concentration semiconductor region thereof varies from the optimal level and/or influenced by the fixed electric charge. The device is produced by forming a ring-shaped high impurity concentration edge termination layer of a second conductivity type and a ring-shaped low impurity concentration RESURF layer of the second conductivity type on the front surface of a semiconductor layer of a first conductivity type carrying electrodes respectively on the opposite surfaces thereof along the outer edge of one of the electrodes, then forming an outer ring layer with an impurity concentration substantially as low as the RESURF layer concentrically outside the RESURF layer with a gap separating therebetween and subsequently forming an inner ring layer with an impurity concentration substantially as high as the edge termination layer concentrically inside the RESURF layer.

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 &lsqb;Acm &rsqb;, the amount of charge of electrons is q&lsqb;C&rsqb;, and the drift speed of carriers is &ugr; &lsqb;cms &rsqb;, the dosage n of the second offset layer is given by n &gE;I /(q &ugr; ) &lsqb;cms &rsqb;.

High-breakdown-voltage semiconductor device

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 &lsqb;Acm,&rsqb;, the amount of charge of electrons is q&lsqb;C&rsqb;, and the drift speed of carriers is &ugr;,&lsqb;cms,&rsqb;, the dosage n,of the second offset layer is given by n,&gE;,/(q&ugr;,)&lsqb;cms,&rsqb;.

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 q�C!, 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 !.

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Kanagawa-ken, Japan

Kozo Kinoshita