GB1096019A - Electrically isolated semiconductor devices and method of producing electrically isolated semiconductor devices on common crystalline substrate - Google Patents

Abstract

<PICT:1096019/C6-C7/1> <PICT:1096019/C6-C7/2> A plurality of electrically isolated semi-conductor regions are carried by a common crystalline substrate and are spaced apart by a grid of crystalline material which may be integral with the substrate. The isolation between the regions and the substrate and the region and the grid is provided by one or more films of insulating material. To produce the arrangement of Fig. 9 a semi-conductor body containing N and N+ layers 10, 11 is provided with a patterned masking layer 20 on the N+ layer. Deep slots are then etched into the body while retaining a unitary structure. The body is then cleaned and an insulating layer 201 formed on the N+ layer and on the walls of the slots. The substrate material is now deposited to fill the slots and form the layer 30 the surface of which is lapped parallel to the surface of the insulation 201. The surface of the N type layer 10 is now lapped parallel to the surface of the substrate and to sufficient depth to separate the original semi-conductor body into isolated regions 35 in which circuit elements are to be produced. The masking layer 20 may be an oxide or nitride layer patterned by photo-resist techniques or the layer may be simply photo-resist material. The embodiment of Fig. 16 may have silicon N and N+ layers 10, 11, a silicon substrate, and silicon dioxide insulating layers. The N+ layer of the starting body 10, 11 is coated with silicon dioxide 201, and a substantially intrinsic silicon substrate layer 30 is deposited on this. An upper silicon masking layer (36) is produced on the N type layer 10 and slots etched through the semi-conductor body to the oxide layer 201. Further silicon dioxide 37 is deposited to coat the walls of the slots and silicon carbide particles are formed on this material to act as nucleating centres when the slots are filled with polycrystalline silicon 40. The upper insulating layer (36) is then lapped off to ready the assembly for further processing. In general suitable substrate materials are silicon, germanium, alumina, and beryllia; suitable materials for the insulating films are silicon dioxide, a silicon nitride (e.g. Si3N4, Si3N2, or SiN), germanium, cadmium sulphide, and intermetallic compounds such as gallium arsenide, gallium phosphide, and indium antimonide. Specific etchants are described which attack some of the semi-conductors listed rather than a silicon oxide or nitride masking layer. Methods of forming silicon dioxide and nitride coatings on silicon and other semi-conductors are described. Polycrystalline silicon may be grown readily on a silicon dioxide film by first depositing carbon on the latter from a colloidal graphite suspension or by the decomposition of a hydrocarbon, by heating the oxide to form particles of silicon carbide on its surface, and by passing over the heated layer hydrogen to which a large quantity of silicon tetrachloride is added - the silicon carbide particles act as nucleating points for the deposited silicon.ALSO:Crystalline silicon is grown on a silicon dioxide film by first depositing carbon on the latter from a colloidal graphite suspension or by the decomposition of a hydrocarbon, then heating the oxide to form particles of silicon carbide on its surface, and passing over the heated layer hydrogen to which a large quantity of silicon tetrachloride is added-the silicon carbon particles act as nucleating points for the deposited silicon.