| 摘要 |
PROBLEM TO BE SOLVED: To inhibit increase in base resistance of a bipolar transistor.SOLUTION: A semiconductor device comprises a base layer BSE which includes a second conductivity type first layer BSE1 and a second base layer BSE2. The second layer BSE2 is located on the first layer and has a composition different from that of the first layer. A second conductivity type impurity concentration of the second layer BSE2 at a connection part of a base extraction electrode BIC and the base layer BSE in a thickness direction is higher than a second conductivity type impurity concentration of the second layer BSE2 at a connection part of an emitter layer EMI and the base layer BSE. In addition, a second conductivity type impurity concentration of the second layer BSE2 at a connection part of the emitter layer EMI and the base layer BSE is lower than a first conductivity type impurity concentration of the second layer BSE2 at a connection part of the emitter layer EMI and the base layer BSE. |
