UN DISPOSITIVO SEMICONDUCTOR.

摘要

1387021 Semi-conductor devices PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd 11 April 1972 [14 April 1971] 16609/72 Heading H1K A semi-conductor device region, e.g. containing active zones 7, 8, is isolated from the remainder of a semiconductor layer 3 and from the substrate 1, 2 by an inset ring 5A of insulating material and by two superposed buried layers 4, 9 of opposite conductivity type and wherein the isolated semi-conductor layer region is divided into two island-shaped regions I, II by a further insulating material region 5B that does not extend through the topmost buried layer 9, in one of which island-shaped regions (I) the semi-conductor circuit element is at least partly provided. The arrangement enables complementary circuit elements, e.g. bipolar transistors, P-N junction FET's, IGFET's or P-N-P-N structures, to be insulated both from each other and from the substrate and constructed as a compact monolithic integrated circuit. In the manufacture of the arrangement shown, boron is diffused into an N-type Si plate 1 to form P-type layers 4, 11 using a thermally grown oxide mask. N-type Si layer 2 is epitaxially grown thereover and N-type layer 9 is formed by diffusing arsenic into the region 4. N-type epitaxial Si layer 3 is then grown and a masking layer of silicon nitride formed thereover and, through holes etched through the silicon nitride, the Si layer 3 is oxidized at 1000‹ C. in moist oxygen to form the inset oxide pattern 5, thus forming island-shaped regions I to V in the layer 3. The island IV is made fully P-type by deep boron diffusion, and P-type zones 13, 7, 14 are formed by less deep boron diffusionwith these diffusions the inset oxide 5 acts as a diffusion mask. Using an apertured oxide layer formed by thermal conversion of SiH4 and O2 N-type zones 8, 15 and N-type contact regions in base zone 12 and island II are formed by phosphorus diffusion. Al contacts 16-25 are formed by vapour deposition and photolithographic etching. Thus two complementary bipolar transistors are provided which may have mutually comparable doping concentrations. P-type zone 7, for example, forming the base zone of a bipolar transistor may have a homogeneous or a varying dopant concentration profile. The buried layers 4, 11 need not be separate and, if desired, may be maintained at a floating potential. The doping of the various regions may alternatively be carried out by ion implantation or by diffusion out of a doped oxide layer.