GB1022159A - Transistors - Google Patents

Abstract

1,022,159. Field effect transistors. STANDARD TELEPHONES & CABLES Ltd. Jan. 29, 1965, No. 4030/65. Heading H1K. A field effect transistor is provided in a semi-conductor layer epitaxially grown on a substrate of the same conductivity type by a process in which the surface of the substrate, before the epitaxial growth, and of the grown layer are doped with the opposite type impurity, this impurity being diffused into the epitaxial layer until the impurity-doped regions link up to form an isolating region surrounding the region containing the channel of the F.E.T. The substrate 1 (Fig. 1A, not shown), may be of P-type silicon with a localized N-type surface region 2 formed by diffusion of antimony or arsenic through an oxide mask. An epitaxially grown P-type silicon layer is then applied over this surface and its own free surface further doped with phosphorus, again by masked diffusion, to form local N-type regions 4 (Fig. 1C, not shown). Continued diffusion causes the regions 2 and 4 to join into a single N-type isolating region surrounding the P-region 5 of Fig. 1D. To the surface of this region are applied ohmic contacts 7, 8 (Fig. 1F, not shown) and a rectifying gate contact 6 between them. In the device of (Fig. 2 not shown), this gate comprises a diffusively doped region linking up with the isolating region, but it could be separate from the latter in which case the latter could function as a second gate. The isolated F.E.T. may form one element in a monolithic circuit block.