GB1281010A - Improvements in and relating to methods of manufacturing semiconductor devices - Google Patents

Abstract

1281010 Semi-conductor devices ASSOCIATED SEMICONDUCTOR MFRS Ltd 22 Oct 1969 [31 Dec 1968] 61955/68 Heading H1K [Also in Division B6] A process for making semi-conductor devices includes the steps of aperturing a masking layer on one face of a semi-conductor wafer and anisotropically etching a pit therethrough, the edges of the aperture and crystal surface being so orientated that the pit has a V-shaped crosssection and a depth directly related to the width of the aperture, providing on the pitted face a rigid support which is insulating at least where it abuts that face and then removing material from the opposite face to expose the bottom of the pit. A plurality of spaced pits of uniform depth may be used to facilitate uniform thinning or pits of varying depths used to permit final control of thinning or contouring of the opposite face. In a typical example an oxide coated 100 orientated Si wafer containing a co-ordinate array of integrated circuits has five spaced 25 Á square apertures the edges of which lie parallel to intersections of 111 planes with the surface in the oxide over the channels between circuits. Treatment in a boiling equimolar mixture of hydrazine and water produces pits 20 Á deep. A glass handle body is deposited on the apertured face and the other face ground to expose the pits, which process is facilitated by illuminating the handle body. Air isolation between circuits and between elements of a circuit is provided by appropriately masking with oxide and etching as before. Individual circuits are finally separated by scribing and fracturing the handle body and potted. Isolation of individual elements of a circuit by PN junctions and solid insulator are suggested alternatives. Other anisotropic etchants which require use of silicon carbide or nitride masking are mixtures of hydrazine, water, and propanol or catechol, and of potassium hydroxide, propanol, and water.