GB1047378A - - Google Patents

Abstract

1,047,378. Transistors. INTERNATIONAL STANDARD ELECTRIC CORPORATION. Sept. 17, 1965 [Sept. 18, 1964], No. 39736/65. Heading H1K. The collector zone of a transistor is commonly heavily doped adjacent the collector electrode and more lightly doped adjacent the collector junction. The higher resistivity adjacent the junction improves the breakdown voltage but detracts from the amplification factor, particularly at high currents. This latter disadvantage is obviated by the invention which provides a further heavily doped region within the lightly doped region and immediately adjacent the junction. Such further region is thin and follows the course of the junction. Fig. 1 (not shown) depicts an NPN planar transistor in which on an N+ substrate an N- layer has been laid, e.g. epitaxially, and part of the surface of this layer has been converted into N+ type by diffusion of further N-type dopant through an oxide mask. Into the diffused N+ region, through the same mask, a P-type base region has been diffused and finally an N-type emitter has been diffused into this through a second and smaller mask. Both masks are left in position to protect the surface junctions. By suitable etching of a similarly produced structure, an alternative mesa-type embodiment may be obtained.