| 摘要 |
A semiconductor device having a semiconductor layer 3 of a first conductivity type which is situated on a substrate region 4 of the second opposite type. Present within an island-shaped region 3A of the layer 3 are a surface-adjoining active zone 8 of the second conductivity type, for example the base zone of a bipolar transistor or the channel region of a field effect transistor, and a juxtaposed highly doped contact zone of the first conductivity type. The thickness and the doping concentration of the layer 3 are so small that the layer is depleted up to the surface 2 at a reverse voltage across the p-n junction 5 of the layer 3 and the substrate region 4 which is lower than the breakdown voltage. According to the invention, a highly doped buried layer 8 is present between the layer 3 and the substrate region 4 and extends at least below at least a portion of the active zone 8, the shortest distance between the edge of the buried layer 11 and the edge of the contact zones 9 being at least equal to (2VB/Ec) where VB is the breakdown voltage of the p-n junction 5, and Ec is the critical field strength above which avalanche multiplication occurs. As a result of this the effect of lateral current concentrations (Kirk effect) is avoided, while a high breakdown voltage is maintained. |
