| 摘要 |
PURPOSE:To obtain the titled device of a high withstand voltage and a large rate of current amplification by a method wherein the base region is formed on the collector region, the center thereof is provided with a recess by etching, and the emitter is formed in the base region by diffusing an impurity in the recess. CONSTITUTION:The surface layer part of a semiconductor substrate serving as the collector region 1 is provided with the base region 2 by impurity diffusion. The recess 4 is bored by etch-removing the center of this surface to a depth of several mum - several tens mum with fluoronitric acid series etchant. Thereafter, the emitter region 3 is formed on the side wall and the bottom surface of the recess 4 by diffusing the impurity therein. In such a manner, the impurity concentration does not decrease even during diffusion until the base width becomes smaller, and the process of diffusion is facilitated. Therefore, the impurity concentration of the region 3 does not decrease till the neighborhood of the junction of the region 2. |
