Schottky barrier semiconductor device having a substantially non-conductive barrier for preventing undesirable reverse-leakage currents and method for making the same

Claim 2

The semi-conductor device according to claim 1, wherein the semi-conductor substrate is of silicon, the insulating fIlm is of silicon dioxide, and the metal layer is a molybdenum film.

Claim 3

A Schottky barrier type transistor which comprises: a semiconductor substrate having a recess formed in a base region thereof, an insulating film covering a major surface portion of said semiconductor substrate and having an opening therethrough, exposing a major part of the bottom of said recess, said opening being disposed above said recess, the cross-sectional area of said opening being less than the cross-sectional area of said recess, so as to provide a separation space in said semiconductor substrate extending around the recess and located underneath the insulating film, a Schottky barrier formed at the bottom of said recess including a metal layer covering the opening in said insulating film and extending through said opening onto the bottom of said recess and the surrounding insulating film while leaving said separation space substantially vacant, said space extending to the base of said recess in said semiconductor substrate where said metal layer forms said Schottky barrier with said substrate and being surrounded by the wall of said recess, so that said Schottky barrier is surrounded by the separation space extending around the recess, another metal layer deposited through a hole opened through the insulating film, so as to make ohmic contact with the base region, and a further metal layer deposited on the part other than the base region of the substrate, so as to make ohmic contact therewith.

Claim 4

The Schottky barrier type transistor according to claim 4, wherein the width of said separation space is at least 1000A.

Claim 5

The Schottky barrier type transistor according to claim 4, wherein the insulating film is of silicon dioxide, and the first metal layer is a molybdenum film.

Claim 6

A Schottky barrier type semiconductor device which comprises: a semiconductor substrate having a recess formed in a specified region; an insulating film of a chemical compound of the semiconductor material covering a major surface portion of said semiconductor substrate but exposing by its opening a major part of said recess with a side-etched separation space extending around the recess located underneath the insulating film; a metal layer covering said recess and the surrounding insulating film while leaving said separation space substantially vacant, and a Schottky barrier which is formed on a contact face between said metal layer and said recess and is surrounded by the separation space, said separation space extending to the base of said recess in said semiconductor substrate at the location where said Schottky barrier is formed and being surrounded by the wall of said recess.

Claim 7

The semi-conductor device according to claim 7, wherein the width of said separation space is at least 1,000 A.

Claim 8

The semi-conductor device according to claim 7, wherein the semi-conductor substrate is made of silicon, the insulating film is made of silicon dioxide, and the metal layer is a molybdenum film.

Claim 9

A semiconductor device with a Schottky barrier, in which an insulating film covers a major surface portion of a semiconductor substrate, in which an opening is provided in the insulating film to expose a defined area of the substrate, and in which a metal layer covers the area of the substrate exposed through the opening to form said Schottky barrier, characterized in that a guard space separating the metal layer from an electric charge accumulation layer is provided to effectively prevent undesirable reverse-leakage currents caused by leakage to the metal layer of electric charges from the accumulation layer formed in parts of the semiconductor substrate closely underneath the insulating film, said guard space comprising a recess formed in said substrate surrounding said metal layer, the cross-sectional area of said opening being less than the cross-sectional area of said recess, so as to provide a separation space in said substrate that Extends around the portion of the recess located underneath said insulating film, said separation space extending to the base of said recess in said semiconductor substrate at the location where said Schottky barrier is formed.

Claim 10

A semiconductor device comprising: a semiconductor substrate having a recess formed in one surface thereof; an insulating film formed on said one surface of said substrate within which said recess is formed, said insulating film overlapping a portion of said recess and having an opening therethrough, the cross-sectional area of which is less than the cross-sectional area of said recess, forming a separation space extending around the edges of the recess and located underneath the overlapping portion of said insulating film; and a Schottky barrier formed at the bottom of said recess comprising a metal layer formed on said insulating film and extending through said opening onto the bottom of said recess so as to form said Schottky barrier between said metal layer and the bottom of said recess, the cross-sectional area of said metal layer which so extends onto the bottom of said recess having a cross-sectional area substantially the same as said opening, said separation space extending to the base of said recess in said semiconductor substrate where said metal layer forms said Schottky barrier with said substrate and being surrounded by the wall of said recess, whereby said separation space remains substantially vacant and said Schottky barrier is surrounded by said separation space formed in said recess, thereby insulating said metal layer from an electric charge accumulation layer in the portion of said substrate adjacent said recess and underneath said insulating film.

Claim 11

The semi-conductor device according to claim 11, wherein the width of said separation space is at least 1,000 A.

Claim 12

The semi-conductor device according to claim 11, wherein the semi-conductor substrate is made of silicon, the insulating film is made of silicon dioxide, and the metal layer is a molybdenum film.

Claim 13

In a Schottky barrier type semiconductor device having a semiconductor substrate, an insulating film covering a major portion of said substrate, an opening extending through said insulating film exposing a defined area of said substrate, and a metal layer covering the area of said substrate exposed through said opening to form a Schottky barrier, the improvement comprising means for effectively preventing undesirable reverse leakage currents caused by leakage to said metal layer of electric charges from an accumulation layer formed in parts of said semiconductor substrate closely beneath said insulating film, said means comprising a substantially non-conductive barrier guard space separating said metal layer from the electric charge accumulation layer, said guard space comprising a recess formed in said substrate surrounding said metal layer beneath said opening, the cross-sectional area of said opening being less than the cross-sectional area of said recess, so as to provide a separation space in said substrate that extends around the portion of the recess located underneath said insulating film, said separation space extending to the base of said recess in said semiconductor substrate at the location where said Schottky barrier is formed.

Claim 14

A field-effect transistor which comprises: a semiconductor substrate having a recess formed in its major surface, an insulating film covering said major surface of said semiconductor substrate and having an opening therethrough, exposing a major part of the bottom of said recess, said opening being disposed above said recess, the cross-sectional area of said opening being less than the cross-sectional area of said recess, so as to provide a separation space extending around the portion of the recess located underneath the insulating film, a Schottky barrier formed at the bottom of said recess including a gate electrode layer covering the opening in said insulating film and extending through said opening onto the bottom of said recess while leaving said separation space substantially vacant, said separation space extending to the base of said recess in said semiconductor substrate at the location where said Schottky barrier is formed, so that said Schottky barrier is surrounded by the separation space extending around the recess, and a source electrode layer and a drain electrode layer, deposited through respective holes opened through the insulating film and located on opposite sides of the gate electrode, so as to make ohmic contact with the substrate.

Claim 15

The field-effect transistor according to claim 15, wherein the width of said separation space is at least 1000A.

Claim 16

The field-effect transistor according to claim 15, wherein the insulating film is of silicon dioxide, and the gate electrode layer is a molybdenum film.