Bipolar transistors and methods of production

Claim 1

A bipolar transistor comprising: a semiconductor substrate (1, 2, 4) of a first conductivity type having an exterior planar surface to which a collector electrode (20C) is connected; a device insulation region (5) selectively formed facing the surface of said semiconductor substrate (1, 2, 4); and a base region (11, 12, 13) of a second conductivity type formed in the semiconductor substrate (1, 2, 4), the base region (11, 12, 13) comprising a graft base region (11) formed on the exterior planar surface of said semiconductor substrate (1, 2, 4) surrounded by said device insulation region (5), said graft base region (11) being formed by diffusion of impurities from a base contact electrode (6) extending over said surface, an intrinsic base region (12) formed at a distance from said graft base region (11) and including an emitter region (14) of the first conductivity type, and a link impurity diffusion region (13) linking said intrinsic base region (12) and said graft base region (11); wherein a diffusion suppression region (15) formed by introduction of the impurities of the first conductivity type is provided in the vicinity of the junction between said base region (11, 12, 13) and the semiconductor substrate (1, 2, 4) of the first conductivity type.

Claim 6

A method of producing a bipolar transistor, the method comprising the steps of: selectively forming a device isolation region (35) on the surface of a semiconductor substrate (31, 32, 34) of a first conductivity type; forming a base contact electrode layer (36) covered by an insulating film (37) extending over a region of the surface of the semiconductor substrate (31, 32, 34) and surrounded at least by the device isolation region (35); introducing, using the base contact electrode layer (36) as a portion of a mask, impurities of a second conductivity type, for forming a link impurity diffusion layer (53) on the surface of said semiconductor substrate (31, 32, 34); introducing impurities of the first conductivity type for forming a diffusion suppression region (55) at the bottom of a region in which a base region is to be formed; forming a graft base region (51) on the surface of said semiconductor substrate (31, 32, 34) by diffusion of impurities of the second conductivity type from the base contact electrode layer (36); forming an intrinsic base region (52) contiguous to said link impurity diffusion region (53) on the surface of said semiconductor substrate (31, 32, 34); and forming an emitter region (54) in said intrinsic base region (52).

Claim 7

A method of producing a bipolar transistor, the method comprising the steps of: selectively forming a device isolation region (35) on the surface of a semiconductor substrate (31, 32, 34) of a first conductivity type; forming a base contact electrode layer (36) covered by an insulating film (37) extending over a region of the surface of the semiconductor substrate (31, 32, 34) and surrounded at least by the device isolation region (35); introducing, using the base contact electrode layer (36) as a portion of a mask, impurities of a second conductivity type, for forming a link impurity diffusion layer (53) on the surface of said semiconductor substrate (31, 32, 34); introducing impurities of the first conductivity type for forming a diffusion suppression region (55) at the bottom of a region in which a base region is to be formed; forming a graft base region (51) on the surface of said semiconductor substrate (31, 32, 34) by diffusion of impurities of the second conductivity type from the base contact electrode layer (36); forming an intrinsic base region (52) contiguous to said link impurity diffusion region (53) on the surface of said semiconductor substrate (31, 32, 34); and forming an emitter region (54) in said intrinsic base region (52).