Method for fabricating a vertical bipolar transistor

Claim 1

A method for fabricating a vertical bipolar transistor, which comprises the steps of: i) implanting a first impurity of a second conductivity type into a portion of a surface of a first conductivity type semiconductor substrate and annealing the implanted first impurity of the second conductivity type to form a first buried layer; ii) implanting a second impurity of the second conductivity type into an upper peripheral portion of said first buried layer, and activating the implanted second impurity of the second conductivity type; iii) defining an active region by growing an epitaxial layer of the first conductivity type on said semiconductor substrate having said first buried layer at a surface portion thereof, and out-diffusing the activated second impurity of the upper peripheral portion of said first buried layer, to form a second buried layer of the second conductivity type, said second buried layer having a higher impurity concentration than that of said first buried layer, both said first buried layer and said second buried layer defining a portion of said epitaxial layer as said active region; iv) forming a base region of the second conductivity type by implanting a third impurity of the second conductivity type into a first upper portion of said active region and annealing the implanted third impurity; and v) completing a fabrication of the vertical bipolar transistor by forming an emitter region, a base contact region and a collector contact region at upper portions of said active region, wherein the step v) comprises the substeps of: a) forming an isolating oxide film on a portion of said active region as well as on an upper portion of said epitaxial layer except said active region; b) forming the emitter region of the first conductivity type at a first upper portion of said base region, and the collector contact region of the first conductivity type at a second upper portion of said active region, said collector contact region having a higher impurity concentration than that of said epitaxial layer; c) forming the base contact region of the first conductivity type at a second upper portion of said base region, said base contact region having a higher impurity concentration than that of said base region; and d) forming a base electrode on a surface of said base region, an emitter electrode on a surface of said emitter region and a collector electrode on a surface of said collector contact region.

Claim 2

A method for fabricating a vertical bipolar transistor, which comprises the steps of: i) implanting a first impurity of a second conductivity type into a portion of a surface of a first conductivity type semiconductor substrate and annealing the implanted first impurity of the second conductivity type to form a first buried layer; ii) implanting a second impurity of the second conductivity type into an upper peripheral portion of said first buried layer, and activating the implanted second impurity of the second conductivity type; iii) defining an active region by growing an epitaxial layer of the first conductivity type on said semiconductor substrate having said first buried layer at a surface portion thereof, and out-diffusing the activated second impurity of the upper peripheral portion of said first buried layer, to form a second buried layer of the second conductivity type, said second buried layer having a higher impurity concentration than that of said first buried layer, both said first buried layer and said second buried layer defining a portion of said epitaxial layer as said active region; iv) forming a base region of the second conductivity type by implanting a third impurity of the second conductivity type into a first upper portion of said active region and annealing the implanted third impurity; and v) completing a fabrication of the vertical bipolar transistor by forming an emitter region, a base contact region and a collector contact region at upper portions of said active region, wherein the step v) comprises the substeps of: a) forming an isolating oxide film on a portion of said active region as well as on an upper portion of said epitaxial layer except said active region; b) forming the emitter region of the first conductivity type at a first upper portion of said base region, and the collector contact region of the first conductivity type at a second upper portion of said active region, said collector contact region having a higher impurity concentration than that of said epitaxial layer; c) forming the base contact region of the first conductivity type at a second upper portion of said base region, said base contact region having a higher impurity concentration than that of said base region; and d) forming a base electrode on a surface of said base region, an emitter electrode on a surface of said emitter region and a collector electrode on a surface of said collector contact region.

Claim 12

A method for fabricating a vertical bipolar transistor, which comprises the steps of: i) implanting a first impurity of a second conductivity type into a portion of a surface of a first conductivity type semiconductor substrate and annealing the implanted first impurity of the second conductivity type to form a first buried layer; ii) implanting a second impurity of the second conductivity type into an upper peripheral portion of said first buried layer, and activating the implanted second impurity of the second conductivity type; iii) defining an active region by growing an epitaxial layer of the first conductivity type on said semiconductor substrate having said first buried layer at a surface portion thereof at the same time as out-diffusing the activated second impurity of the upper peripheral portion of said first buried layer, to form a second buried layer of the second conductivity type, said second buried layer having higher impurity concentration than that of said first buried layer, both said first buried layer and said second buried layer defining a portion of said epitaxial layer as said active region; iv) forming a subcollector region of the first conductivity type at said active region above said first buried layer; v) forming an isolating oxide film on a portion of said active region and on said epitaxial layer except said active region; vi) forming a base region of the second conductivity type by implanting a third impurity of the second conductivity type into a first upper portion of said active region, and annealing the implanted third impurity of the second conductivity type; vii) forming an emitter region of the first conductivity type at a first upper portion of said base region at the same time as forming a collector contact region of the first conductivity type at a second upper portion of said active region, said collector contact region having a higher impurity concentration than that of said epitaxial layer; viii) forming a base contact region of the first conductivity type at a second upper portion of said base region, said base contact region having a higher impurity concentration than that of said base region; and ix) forming a base electrode on a surface of said base contact region, an emitter electrode on a surface of said emitter region and a collector electrode on a surface of said collector contact region.

Claim 13

A method for fabricating a vertical bipolar transistor, which comprises the steps of: i) implanting a first impurity of a second conductivity type into a portion of a surface of a first conductivity type semiconductor substrate and annealing the implanted first impurity of the second conductivity type to form a first buried layer; ii) implanting a second impurity of the second conductivity type into an upper peripheral portion of said first buried layer, and activating the implanted second impurity of the second conductivity type; iii) defining an active region by growing an epitaxial layer of the first conductivity type on said semiconductor substrate having said first buried layer at a surface portion thereof at the same time as out-diffusing the activated second impurity of the upper peripheral portion of said first buried layer, to form a second buried layer of the second conductivity type, said second buried layer having higher impurity concentration than that of said first buried layer, both said first buried layer and said second buried layer defining a portion of said epitaxial layer as said active region; iv) forming a subcollector region of the first conductivity type at said active region above said first buried layer; v) forming an isolating oxide film on a portion of said active region and on said epitaxial layer except said active region; vi) forming a base region of the second conductivity type by implanting a third impurity of the second conductivity type into a first upper portion of said active region, and annealing the implanted third impurity of the second conductivity type; vii) forming an emitter region of the first conductivity type at a first upper portion of said base region at the same time as forming a collector contact region of the first conductivity type at a second upper portion of said active region, said collector contact region having a higher impurity concentration than that of said epitaxial layer; viii) forming a base contact region of the first conductivity type at a second upper portion of said base region, said base contact region having a higher impurity concentration than that of said base region; and ix) forming a base electrode on a surface of said base contact region, an emitter electrode on a surface of said emitter region and a collector electrode on a surface of said collector contact region.