Semiconductor device and manufacturing method thereof

Abstract

The present invention provides a semiconductor device. In the existing semiconductor device, high break down voltage NPN transistor with high frequency characteristics is difficult formed. In the semiconductor device of the present invention, an N type epitaxial layer (4) is formed on a P type silicon substrate (3). In the N type epitaxial layer (4), P type diffusion layers (31, 32) as a base region, N type diffusion layers (27-30) as collector regions and an N type diffusion layer (35) as an emitter region are formed. In this event, the P type diffusion layers (31-32) are formed so as to have a double diffusion structure, and an impurity concentration in a surface of the base region and in a region adjacent thereto is set high. This structure enables improvement in high frequency characteristics and in a current amplification factor while maintaining breakdown voltage characteristics of an NPN transistor (2).

Description

technical field [0001] The invention relates to a semiconductor device aimed at improving the high-frequency characteristics and current amplification rate of a transistor. Background technique [0002] As an example of a conventional semiconductor device and its manufacturing method, the following NPN transistor is known. On the P-type silicon semiconductor substrate, an N-type epitaxial layer is formed. On the epitaxial layer, an extrinsic base region is formed around it in such a way as to surround the active base region. The extrinsic base region is connected to the extrinsic base extraction electrode formed on the epitaxial layer. Furthermore, an emitter region is formed on the active base region, and the emitter region is connected to an emitter extraction electrode. In addition, a collector region is formed on the epitaxial layer. At this time, impurities in the extrinsic base extraction electrode are diffused into the epitaxial layer to form an extrinsic base reg...

AI Technical Summary

Problems solved by technology

However, the diffusion layer used as the internal base region has a low concentration and a deep diffusion depth, resulting in a high base resistance value, which makes it difficult to obtain the desired high-frequency characteristics and current amplification rate of the NPN transistor.

Images