| 摘要 |
PURPOSE:To obtain a low-noise planar-type transistor with reduced number of processes by a method wherein an emitter region which has the large diffusion depth and high density of impurities, and another emitter region which surrounds the former and has small depth and low density of impurites are formed in the same stage of preparation. CONSTITUTION:On the back surface of an n type Si substrate 1 which becomes a collector region is formed an n<+> type layer 2 diffusively, while on the front surface thereof is provided an SiO2 film 3, and in the window made in the film is formed a p type base region 4 diffusively. Next, an SiO2 film 5 is fitted on to the region 4 exposed in the window, while a window 15a of width W1 is made, positioned in the central part of the region 4, and further a window 15b of width W2 is opened around the window 15a, apart in a distance of 2-3m from the latter. After that, n type impurities are diffused within the region 4 exposed in these windows 15a and 15b, thereby the deep n<+> type emitter region 16 and the shallow n type emitter region 17 are formed therein, and the regions 16 and 17 are connected with each other by making use of the short distance S between the windows 15a and 15b. After thus being constituted, an emitter, base and collector electrode 8-10 are attached to respective regions. |
