Bipolar type semiconductor device having small parasitic capacitance, small dimensions, and small variation in transistor characteristics

Claim 2

A bipolar type semiconductor device, comprising: a collector region of a first conductivity type; an intrinsic base region of a second conductivity type provided on said collector region; an emitter region of the first conductivity type provided by self-alignment with respect to said intrinsic base region; a base electrode layer structure provided around said intrinsic base region at a periphery thereof; a base contact electrode above and in contact with a portion of said base electrode layer structure; a trench-type element isolation region provided by self-alignment in contact with and around said base electrode layer at an outer circumference thereof; and a graft base underlying and in contact with said base electrode layer structure and also around and in contact with a periphery of said intrinsic base region, and an outer periphery of said graft base terminating at said trench-type element isolation region.

Claim 3

A bipolar type semiconductor device according to claim 1 wherein said base electrode layer structure comprises first and second directly abutting layers.

Claim 4

A bipolar type semiconductor device, comprising: a collector region of a first conductivity type on a semiconductor substrate; an intrinsic base region of a second conductivity type provided on said collector region; an emitter region of the first conductivity type provided by self-alignment with respect to said intrinsic base region; a base electrode provided in a trench at a surface of said semiconductor substrate and surrounding said intrinsic base region at a periphery thereof; a column-like projection portion in which said intrinsic base region, said emitter region, and an emitter take-out electrode are arranged in a vertical direction, said trench surrounding said column-like projection portion; and a graft base provided in a bottom portion of said trench and connecting to said intrinsic base region only at a bottom portion thereof beneath said column-like projection portion and also connecting with said base electrode in said trench.

Claim 5

A bipolar type semiconductor device, comprising: a collector region of a first conductivity type on a semiconductor substrate; an intrinsic base region of a second conductivity type provided on said collector region; an emitter region of the first conductivity type provided by self-alignment with respect to said intrinsic base region; a base electrode provided in a trench at a surface of said semiconductor substrate and surrounding said intrinsic base region at a periphery thereof; a column-like projection portion in which said intrinsic base region, said emitter region, and an emitter take-out electrode are arranged in a vertical direction, said trench surrounding said column-like projection portion; and a graft base provided in a bottom portion of said trench and connecting to said intrinsic base region only at a bottom portion thereof beneath said column-like projection portion and also connecting with said base electrode in said trench.

Claim 6

A device according to claim 3 wherein a base contacting electrode is electrically connected to said base electrode at one side in said trench.

Claim 7

A bipolar type semiconductor device, comprising: a collector region of a first conductivity type on a semiconductor substrate; an intrinsic base region of a second conductivity type provided on said collector region; an emitter region of the first conductivity type provided by self-alignment with respect to said intrinsic base region; a base electrode provided in a first trench at a surface of said semiconductor substrate and surrounding said intrinsic base region at a periphery thereof; a column-like projection portion in which said intrinsic base region, said emitter region, and an emitter take-out electrode are arranged in a vertical direction, said first trench surrounding said column-like projection portion; a graft base in a bottom portion of said first trench which is in contact only with a bottom portion of said intrinsic base and also connects with said base electrode in said first trench; and an outer circumference of said graft base being defined by a second trench provided in an outer region of the bottom portion of said first trench.

Claim 8

A bipolar type semiconductor device, comprising: a collector region of a first conductivity type on a semiconductor substrate; an intrinsic base region of a second conductivity type provided on said collector region; an emitter region of the first conductivity type provided by self-alignment with respect to said intrinsic base region; a base electrode provided in a first trench at a surface of said semiconductor substrate and surrounding said intrinsic base region at a periphery thereof; a column-like projection portion in which said intrinsic base region, said emitter region, and an emitter take-out electrode are arranged in a vertical direction, said first trench surrounding said column-like projection portion; a graft base in a bottom portion of said first trench which is in contact only with a bottom portion of said intrinsic base and also connects with said base electrode in said first trench; and an outer circumference of said graft base being defined by a second trench provided in an outer region of the bottom portion of said first trench.

Claim 9

A bipolar type semiconductor device according to claim 5 wherein a base contact electrode is provided at one side of said trench in electrical contact with said base electrode.