Patent ID: 7880270

Claim:
A vertical heterobipolar transistor comprising: a substrate ( 210 ; 300 ) of semiconductor material of a first conductivity type and an insulation region ( 212 ; 327 ) provided therein, a first semiconductor region ( 220 ; 326 ) arranged in an opening in the insulation region ( 212 ; 327 ) and comprising monocrystalline semiconductor material of a second conductivity type which is either in the form of a collector or an emitter and which has a first heightwise portion ( 220 a ) which is enclosed by the insulation region in lateral directions (I) perpendicular to a heightwise direction (h) and has an adjoining second heightwise portion ( 230 a ) which is further away from the substrate interior in the heightwise direction (h) and which is laterally not enclosed by the insulation region, a second semiconductor region ( 260 ; 318 ) of semiconductor material of the second conductivity type which is in the form of the other type of semiconductor region and is thus in the form of an emitter or alternatively a collector respectively, a base ( 230 c ; 314 ) of monocrystalline semiconductor material of the first conductivity type between the collector and the emitter, and a base connection region ( 233 ; 320 ) which has a monocrystalline portion ( 233 a , 233 b , 233 c , 233 d , 233 e ) which in a lateral direction laterally surrounds the second heightwise portion ( 230 a ) of the first semiconductor region ( 220 ; 326 ), that is further towards the substrate interior as viewed from the base, and which with its underside facing towards the substrate interior is disposed directly on the insulation region ( 212 ; 327 ) and which is referred to hereinafter as a vertically insulated monocrystalline base connection region portion, for brevity a VIMBCR portion, wherein the lateral extent of a heightwise portion ( 233 a ) of the VIMBCR portion ( 233 a , 233 b , 233 c , 233 d , 233 e ) which laterally surrounds the second heightwise portion ( 230 a ) of the second semiconductor region ( 220 ) is greater than the spacing measured in the heightwise direction between an upper edge of the insulation region ( 212 ) and a lower edge of the base ( 230 c ).