Power semiconductor device

Claim 2

A semiconductor pellet having first and second major surfaces and at least three successive semiconductor layers including a first outermost layer having a first side which is exposed to said first major surface and having a first conductivity type, a first intermediate layer having a second conductivity type opposite to said first conductivity type, said first intermediate layer having a first side which is formed adjacent to a second side of said first outermost layer and including a portion which is exposed to said first major surface, and a third layer having said first conductivity type and having a first side which is formed adjacent to a second side of said first intermediate layer, wherein said first outermost layer includes a common portion exposed to said first major surface and at least tow fingershaped split areas exposed to said first major surface and extending from said common portion wherein said common portion electrically connects said split areas to one another; an insulating film formed on said common portion at said first major surface; and a first electrode connected with said first outermost layer and including areas which directly make low ohmic contact with said split areas and an area which overlies the common portion only through said insulating film so that said first electrode is insulated from said common portion by said insulating film.

Claim 3

A semiconductor device according to claim 1, wherein said portion of said first intermediate layer which is exposed to said first major surface surrounds said first side of said first outermost layer which is exposed to said first major surface.

Claim 4

A semiconductor device according to claim 2, wherein said first outermost layer is formed to have a shape which will include a geometric projection of said first electrode projected in a direction vertical to the first and second major surfaces, thereby preventing a short-circuit of said first electrode to said first intermediate layer even upon occurrence of a pinhole in said insulating film.

Claim 5

A semiconductor device according to claim 3, wherein said area of the first electrode overlying the insulating film has an area sufficient for bonding a lead wire and the common portion of said first outermost layer underlying the insulating film has a lateral resistance which is larger than a longitudinal resistance of an area of at least two finger-shaped split areas ohmically contacting said first electrode.

Claim 6

A semiconductor device according to claim 3, wherein said third layer comprises a second intermediate layer of said first conductivity type having a first side formed adjacent to said second side of said first intermediate layer, wherein said pellet further comprises a second outermost layer of said second conductivity type having a first side formed adjacent to a second side of said second intermediate layer and having a second side which is exposed to said second major surface, and wherein said device further comprises a second electrode coupled to make low ohmic contact with said second side of said second outermost layer and a control electrode coupled to make ohmic contact with said portion of said first intermediate layer which is exposed to said first major surface.

Claim 7

A semiconductor device according to claim 3, wherein said third layer comprises a second outermost layer which has a first side formed adjacent to said second side of said first intermediate layer and which has a second side exposed to said second major surface, and further wherein said device comprises a second electrode coupled to make low ohmic contact with said second side of said second outermost layer and a control electrode coupled to make low ohmic contact with said portion of said first intermediate layer which is exposed to said first major surface.

Claim 8

A semiconductor device according to claim 3, wherein said insulating film is made of one material selected from the group consisting of silicon oxide, silicon nitride, glass, resin and combinations thereof.

Claim 9

A semiconductor device according to claim 5, wherein said second intermediate layer surrounds said second outermost layer and is exposed to said second major surface.

Claim 10

A semiconductor device according to claim 8, wherein said second intermediate layer includes a high resistivity region adjacent to the second side of said first intermediate layer and separated from said first and second major surfaces and a low resistivity region disposed between said high resistivity region and said second major surface.

Claim 11

A semiconductor device according to claim 9, wherein said low resistivity region has a larger dimension perpendicular to said major surfaces than said second outermost layer.

Claim 12

A semiconductor device according to claim 8, wherein said second outermost layer includes at least two split areas which are substantially in register with said at least two finger-shaped split areas of said first outermost layer.

Claim 13

A semiconductor device according to claim 3, wherein said third layer is an outermost layer disposed between said first intermediate layer and said second major surface, and wherein said first outermost layer, said first intermediate layer and said third layer form an emitter, a base and a collector region, respectively, of a bipolar transistor.

Claim 14

A semiconductor thyristor device including a first semiconductor region having a first conductivity type, a second semiconductor region disposed adjacent to the first region and having a second conductivity type which is opposite to said first conductivity type, a third semiconductor region disposed adjacent to the second region and having said first conductivity type and a fourth semiconductor region disposed adjacent to the third region and having said second conductivity type, and provided with a first and a second current electrode formed on said first and said fourth semiconductor regions, respectively, for allowing a current to flow therebetween, through said first, second, third and fourth regions, said thyristor device comprising: said second region having a first major surface; said first region formed in the second semiconductor region and exposed to said first major surface, the first region including a common portion exposed to said first major surface and at least two finger-shaped portions exposed to said first major surface and extending from said common portion, wherein said common portion electrically connects said finger-shaped portions to one another; the first current electrode disposed on said first region at said first major surface and having a common portion and at least two finger-shaped portions which extend from said common portion and which make ohmic contacts with said finger-shaped portions of the first region; and an insulating film disposed between said common portion of the first semiconductor region and said common portion of the electrode, wherein said common portion of said first electrode overlies said common portion of the first semiconductor region only through said insulating film so that said first electrode is insulated from said common portion of said first electrode by said insulating film.

Claim 15

A semiconductor thyristor device including a first semiconductor region having a first conductivity type, a second semiconductor region disposed adjacent to the first region and having a second conductivity type which is opposite to said first conductivity type, a third semiconductor region disposed adjacent to the second region and having said first conductivity type and a fourth semiconductor region disposed adjacent to the third region and having said second conductivity type, and provided with a first and a second current electrode formed on said first and said fourth semiconductor regions, respectively, for allowing a current to flow therebetween, through said first, second, third and fourth regions, said thyristor device comprising: said second region having a first major surface; said first region formed in the second semiconductor region and exposed to said first major surface, the first region including a common portion exposed to said first major surface and at least two finger-shaped portions exposed to said first major surface and extending from said common portion, wherein said common portion electrically connects said finger-shaped portions to one another; the first current electrode disposed on said first region at said first major surface and having a common portion and at least two finger-shaped portions which extend from said common portion and which make ohmic contacts with said finger-shaped portions of the first region; and an insulating film disposed between said common portion of the first semiconductor region and said common portion of the electrode, wherein said common portion of said first electrode overlies said common portion of the first semiconductor region only through said insulating film so that said first electrode is insulated from said common portion of said first electrode by said insulating film.

Claim 16

A semiconductor thyristor device according to claim 13, wherein said common portion of said first current electrode has dimensions sufficient for lead bonding and said first region is registered with said first current electrode and has an area at said first major surface which area includes a geometric projection of said first current electrode projected in a direction perpendicular to said first major surface.

Claim 17

A semiconductor thyristor device according to claim 14, further including a control electrode disposed on said second region for controlling the current, the third semiconductor region having a second major surface, and the fourth semiconductor region formed in said third semiconductor region, exposed to said second major surface, and being substantially in register with said finger-shaped portions of said first region.

Claim 18

A semiconductor thyristor device according to claim 15, wherein said insulating film defines contact areas at said first major surface at which said first current electrode makes ohmic contact with said first region and wherein each of said contact areas extends a predetermined distance into said common portion of the first region and has a predetermined curved boundary within said common portion at said first major surface.

Claim 19

A semiconductor thyristor device according to claim 15, wherein said insulating film defines contact areas at which said first current electrode make ohmic contact with said first region, said control electrode and said first current electrode have an interdigital configuration, and said contact areas are confined within interspaces between finger-shaped portions of said control electrode.

Claim 20

A semiconductor bipolar transistor device including an emitter semiconductor region having a first conductivity type, a base semiconductor region disposed adjacent to the emitter region and having a second conductivity type which is opposite to said first conductivity type, and a collector semiconductor region disposed adjacent to the base region and having said first conductivity type, and provided with an emitter and a collector electrode formed on said emitter and said collector semiconductor regions, respectively, for allowing a current to flow therebetween, comprising: said base region having a first major surface; said emitter region formed in the base semiconductor region and exposed to said first major surface, the emitter region including a common portion exposed to said first major surface and at least two finger-shaped portions exposed to said first major surface and extending from said common portion, wherein said common portion electrically connects said finger-shaped portions to one another; said collector region having a second major surface on which said collector electrode is disposed; the emitter electrode disposed on and within an area of said emitter region at said first major surface and having a common portion and finger-shaped portions which extend from said common portion and which make ohmic contact with said finger-shaped portions of the first region; and an insulating film disposed between said common portion of the first semiconductor region and said common portion of the first electrode, wherein said common portion of said first electrode overlies said common portion of the first semiconductor region only through said insulating film so that said first electrode is insulated from said common portion of said first electrode by said insulating film.

Claim 21

A semiconductor bipolar transistor device including an emitter semiconductor region having a first conductivity type, a base semiconductor region disposed adjacent to the emitter region and having a second conductivity type which is opposite to said first conductivity type, and a collector semiconductor region disposed adjacent to the base region and having said first conductivity type, and provided with an emitter and a collector electrode formed on said emitter and said collector semiconductor regions, respectively, for allowing a current to flow therebetween, comprising: said base region having a first major surface; said emitter region formed in the base semiconductor region and exposed to said first major surface, the emitter region including a common portion exposed to said first major surface and at least two finger-shaped portions exposed to said first major surface and extending from said common portion, wherein said common portion electrically connects said finger-shaped portions to one another; said collector region having a second major surface on which said collector electrode is disposed; the emitter electrode disposed on and within an area of said emitter region at said first major surface and having a common portion and finger-shaped portions which extend from said common portion and which make ohmic contact with said finger-shaped portions of the first region; and an insulating film disposed between said common portion of the first semiconductor region and said common portion of the first electrode, wherein said common portion of said first electrode overlies said common portion of the first semiconductor region only through said insulating film so that said first electrode is insulated from said common portion of said first electrode by said insulating film.