| 摘要 |
PURPOSE:To strengthen the resistivity to a surge voltage by avoiding concentration of field to the edge of an emitter. CONSTITUTION:An emitter region 3 is formed within a base region 2. A graft- base region 4 is a high impurity concentration region provided for extending a base electrode. On the occasion of forming the graft-base region 4, a high impurity concentration region 4' is formed simultaneously under the emitter region 3. Thereby, zener yielding of a zener diode occurs at the entire part of junction area 6 between the emitter region 3 and high impurity concentration region 4'. Therefore, such yielding point becomes equal, as an electrostatic breakdown strength, to difference of impurity concentrations of the emitter region 3 and high impurity concentration region 4' and a theoretical strength determined by the junction area. |
