GB1279167A - Method of manufacturing beam lead integrated circuits - Google Patents

Abstract

1279167 Integrated semi-conductor devices ITT INDUSTRIES Inc 17 Sept 1970 [22 Sept 1969] 44419/70 Heading H1K A beam lead integrated circuit device is fabricated on a sandwich of a silicon substrate covered with aluminosilicate glass frit 2 in alcoholic suspension overlaid by a silicon wafer 3a the sandwich being placed between carbon susceptors of an hydraulic press and RF induction heated to 1200‹ C. under 1200 p.s.i., after which it is cooled under pressure. The wafer may alternatively be of germanium or gallium arsenide. It is parallel lapped or etched and polished to ¢ mil, and formed with a number of active or passive electrical components 4 by known photolitho masking, diffusion and deposition techniques. Alternatively the components may be preformed in the wafer, which is then applied to the substrate over a low temperature glaze and heated to a softening point lower than the diffusion temperature. A passivation layer 5 of evaporated silicon dioxide or RF glow discharge deposited silicon nitride is formed on the wafer, and holes are etched with NH 4 F + HF to expose terminals of the discrete components, and a metallized layer of e.g. aluminium is deposited by electron beam or filamentary evaporation or glow discharge. The required interconnecting lead pattern is formed by selectively etching with, e.g. NaOH through photoresist. Alternatively the lead pattern may be of a sandwich of Pt, Ti and Au in that order. Layer 5 is etched through photoresist with NH 4 F + HF to remove a portion surrounding each component, and abutting the leads 6. The exposed wafer surface is etched using HF+ HNO 3 + CH 3 .COOH to remove the exposed silicon to the glass layer and to undercut leads 6 without penetrating sufficiently under layer 5 to damage the components, which are thus isolated. The substrate may be divided using known scribing methods into separate integrated circuit devices.