Semiconductor device having composite substrate formed by fixing two semiconductor substrates in close contact with each other

Claim 2

A semiconductor device comprising: a first semiconductor substrate having first and second surfaces; a second semiconductor substrate having a third surface in which crystal defects are formed in a surface region thereof, and a fourth surface, said third surface being directly bonded to the first surface of said first semiconductor substrate; and at least one semiconductor element formed in a composite substrate formed by directly bonding said first and second semiconductor substrates; wherein said crystal defects are formed by ion-implanting atoms into the surface region of said second semiconductor substrate, said atoms are selected from those which function as neither an acceptor or a donor in said second semiconductor substrate, and said atoms do not introduce oxygen into said second semiconductor substrate.

Claim 3

A semiconductor device according to claim 1, further comprising crystal defects formed in a surface region of said first surface of said first semiconductor substrate.

Claim 4

A semiconductor device according to claim 1, wherein said atoms are preferably selected from a group consisting of Ar, Kr, Xe, and Rn.

Claim 5

A semiconductor device according to claim 1, wherein said atoms are preferably a desired combination of atoms selected from a group consisting of Ar, Kr, Xe, and Rn.

Claim 6

A semiconductor device according to claim 1, wherein said first semiconductor substrate is of a first conductivity type and a high impurity concentration, said second semiconductor substrate is of a second conductivity type and a low impurity concentration, and said semiconductor element is an insulated gate bipolar transistor.

Claim 7

A semiconductor device according to claim 1, wherein said first semiconductor substrate is of a first conductivity type and a high impurity concentration, said second semiconductor substrate is of a second conductivity type and a low impurity concentration, and said semiconductor element is a reverse blocking triode thyristor.

Claim 8

A semiconductor device comprising: a composite substrate formed by fixing a first semiconductor substrate of a first conductivity type and a low impurity concentration, and a second semiconductor substrate of a second conductivity type and a high impurity concentration, crystal defects being formed in said composite substrate, near a junction plane of said first and second semiconductor substrates; a first impurity region, of the first conductivity type and a high impurity concentration, formed in a portion of said first semiconductor substrate which lies near the junction plane of said first and second semiconductor substrates; a second impurity region, of the second conductivity type, formed in a surface area of said composite substrate; a third impurity region, of the first conductivity type and a high impurity concentration, formed in a surface area of said second impurity region; a gate insulation film formed on a portion of said first semiconductor substrate surrounded by said second impurity region; a gate electrode formed on said gate insulation film; a source electrode formed on said second and third impurity regions; and a drain electrode formed on a back surface of said composite substrate; wherein said crystal defects are formed by ion-implanting atoms into a surface area of at least one of said first and second semiconductor substrates, said atoms are selected from those which function as neither an acceptor nor a donor in said first and second semiconductor substrates, and said atoms do not introduce oxygen into said at least one of said first and second semiconductor substrates.

Claim 9

A semiconductor device comprising: a composite substrate formed by fixing a first semiconductor substrate of a first conductivity type and a low impurity concentration, and a second semiconductor substrate of a second conductivity type and a high impurity concentration, crystal defects being formed in said composite substrate, near a junction plane of said first and second semiconductor substrates; a first impurity region, of the first conductivity type and a high impurity concentration, formed in a portion of said first semiconductor substrate which lies near the junction plane of said first and second semiconductor substrates; a second impurity region, of the second conductivity type, formed in a surface area of said composite substrate; a third impurity region, of the first conductivity type and a high impurity concentration, formed in a surface area of said second impurity region; a gate insulation film formed on a portion of said first semiconductor substrate surrounded by said second impurity region; a gate electrode formed on said gate insulation film; a source electrode formed on said second and third impurity regions; and a drain electrode formed on a back surface of said composite substrate; wherein said crystal defects are formed by ion-implanting atoms into a surface area of at least one of said first and second semiconductor substrates, said atoms are selected from those which function as neither an acceptor nor a donor in said first and second semiconductor substrates, and said atoms do not introduce oxygen into said at least one of said first and second semiconductor substrates.

Claim 10

A semiconductor device according to claim 7, wherein said atoms are preferably selected from a group consisting of Ar, Kr, Xe, and Rn.

Claim 11

A semiconductor device according to claim 7, wherein said atoms are preferably a desired combination of atoms selected from a group consisting of Ar, Kr, Xe, and Rn.

Claim 12

A semiconductor device comprising: a composite substrate formed by fixing a first semiconductor substrate of a first conductivity type and a low impurity concentration, and a second semiconductor substrate of a second conductivity type and a high impurity concentration, crystal defects being formed in said composite substrate, near a junction plane of said first and second semiconductor substrates; a first impurity region, of a second conductivity type, formed in a surface area of said composite substrate; a second impurity region, of the first conductivity type and a high impurity concentration, formed in a surface area of said first impurity region; a cathode electrode formed on said second impurity region; a gate electrode formed on said first impurity region; and an anode electrode formed on a back surface of said composite substrate; wherein said crystal defects are formed by ion-implanting atoms into a surface area of at least one of said first and second semiconductor substrates, said atoms are selected from those which function as neither an acceptor nor a donor in said first and second semiconductor substrates, and said atoms do not introduce oxygen into said at least one of said first and second semiconductor substrates.

Claim 13

A semiconductor device comprising: a composite substrate formed by fixing a first semiconductor substrate of a first conductivity type and a low impurity concentration, and a second semiconductor substrate of a second conductivity type and a high impurity concentration, crystal defects being formed in said composite substrate, near a junction plane of said first and second semiconductor substrates; a first impurity region, of a second conductivity type, formed in a surface area of said composite substrate; a second impurity region, of the first conductivity type and a high impurity concentration, formed in a surface area of said first impurity region; a cathode electrode formed on said second impurity region; a gate electrode formed on said first impurity region; and an anode electrode formed on a back surface of said composite substrate; wherein said crystal defects are formed by ion-implanting atoms into a surface area of at least one of said first and second semiconductor substrates, said atoms are selected from those which function as neither an acceptor nor a donor in said first and second semiconductor substrates, and said atoms do not introduce oxygen into said at least one of said first and second semiconductor substrates.

Claim 14

A semiconductor device according to claim 10, wherein said atoms are preferably selected from a group consisting of Ar, Kr, Xe, and Rn.

Claim 15

A semiconductor device according to claim 10, wherein said atoms are a desired combination of atoms selected from a group consisting of Ar, Kr, Xe, and Rn.