Semiconductor device

Claim 2

In a semiconductor switching device having at least three alternate semiconductor layers formed substantially in parallel with a crystal plane indicated by {100 } in Miller indices; a high impurity atom concentration control layer P 2 ++ buried in one of said at least three alternate semiconductor layers; and a plurality of long and narrow current channels CH formed in said high impurity atom concentration control layer P 2 ++ , an anode A and a cathode k being formed on either outer side of said at least three alternate semiconductor layers, an anode current flowing from said anode A to said cathode k through said current channels CH perpendicularly to the crystal plane indicated by {100 } being controlled by a control current flowing through said high impurity atom concentration control layer P 2 ++ in a direction substantially parallel to the crystal plane indicated by {100 }, the improvement wherein plural longitudinal directions of said current channels CH formed in said high impurity atom concentration control layer P 2 ++ are substantially in parallel with at least one of crystal axes indicated by <100> on condition that inner product of a crystal axis vector and a crystal plane vector is zero.

Claim 3

The semiconductor switching device as set forth in claim 1, wherein said switching device is a gate turn-off thyristor.

Claim 4

The semiconductor switching device as set forth in claim 1, wherein said switching device is a thyristor.

Claim 5

The semiconductor switching device as set forth in claim 1, wherein said switching device is a static induction transistor.

Claim 6

The semiconductor switching device as set forth in claim 1, wherein said switching device is an field effect transistor.

Claim 7

In a gate turn-off thyristor having four alternately-different PNPN semiconductor layers of: (a) a first P-type layer P 1 having an anode; (b) a first N-type layer N 1 adjoining to the first P-type layer P 1 ; and (c) a second P-type layer including: a first impurity atom concentration layer P 2 adjoining to the first N-type layer N 1 ; a second impurity atom concentration layer P 2 - adjoining to the first impurity atom concentration layer P 2 , a second concentration in the second impurity atom concentration layer P 2 - being lower than a first concentration in the first impurity atom concentration layer P 2 ; and a third low-resistance impurity atom concentration layer P 2 ++ buried in the first impurity atom concentration layer P 2 and between the first and second layers P 2 and P 2 - , current channels CH being formed between the third low resistance layers P 2 ++ ; and (d) a second N-type layer N 2 formed in the second impurity atom concentration layer P 2- and having a cathode, the improvement wherein said third low-resistance impurity atom concentration layer P 2 ++ is formed on a crystal plane indicated by {100 } in Miller indices and at least one longitudinal direction of the current channels CH formed between the third low resistance layers P 2 ++ is arranged substantially in parallel with at least one of crystal axes indicated by <100> on the crystal plane {100 } on condition that inner product of the crystal axis vector and the crystal plane vector is zero.

Claim 8

In a gate turn-off thyristor having four alternately-different PNPN semiconductor layers of: (a) a first P-type layer P 1 having an anode; (b) a first N-type layer N 1 adjoining to the first P-type layer P 1 ; and (c) a second P-type layer including: a first impurity atom concentration layer P 2 adjoining to the first N-type layer N 1 ; a second impurity atom concentration layer P 2 - adjoining to the first impurity atom concentration layer P 2 , a second concentration in the second impurity atom concentration layer P 2 - being lower than a first concentration in the first impurity atom concentration layer P 2 ; and a third low-resistance impurity atom concentration layer P 2 ++ buried in the first impurity atom concentration layer P 2 and between the first and second layers P 2 and P 2 - , current channels CH being formed between the third low resistance layers P 2 ++ ; and (d) a second N-type layer N 2 formed in the second impurity atom concentration layer P 2- and having a cathode, the improvement wherein said third low-resistance impurity atom concentration layer P 2 ++ is formed on a crystal plane indicated by {100 } in Miller indices and at least one longitudinal direction of the current channels CH formed between the third low resistance layers P 2 ++ is arranged substantially in parallel with at least one of crystal axes indicated by <100> on the crystal plane {100 } on condition that inner product of the crystal axis vector and the crystal plane vector is zero.

Claim 9

The gate turn-off thyristor as set forth in claim 6, wherein said third low-resistance impurity atom concentration layer P 2 ++ is formed on a specific silicon crystal plane indicated by (100) and the longitudinal direction of the current channels CH is arranged substantially in parallel with a specific silicon crystal axis indicated by [010] on the specific silicon crystal plane (100).

Claim 10

The gate turn-off thyristor as set forth in claim 6, wherein said third low resistance impurity atom concentration layer P 2 ++ is formed on a specific silicon crystal plane (100) and the longitudinal direction of the current channels CH is arranged substantially in parallel with a specific silicon crystal axis indicated by [001] on the specific silicon crystal plane (100).

Claim 11

The gate turn-off thyristor as set forth in claim 6, wherein said third low resistance impurity atom concentration layer P 2 ++ is divided into four portions in a specific silicon crystal plane (100) and the longitudinal directions of biaxial current channels CH are arranged substantially in parallel with two specific silicon crystal axes indicated by [010], and [001] on the specific silicon crystal plane (100), respectively.

Claim 12

In the semiconductor switching device as set forth in claim 1, wherein a crystal for forming said at least three alternate semiconductor layers is crystallographically isotropic.