| 摘要 |
1,203,087. Integrated circuits. TEXAS INSTRUMENTS Inc. 15 Sept., 1967 [30 Dec., 1966], No. 13609/70. Divided out of 1,203,086. Heading H1K.. [Also in Division C7] In an integrated circuit comprising a passivated semi-conductor wafer with a plurality of circuit elements at one surface joined by first level interconnections lying on the passivation layer, one or more further levels of interconnections insulated from the first level are provided. The connections of each level include a layer of molybdenum, titanium, tantalum, rhodium, cobalt, nickel or aluminium, and the uppermost level has an overlayer of gold. In a typical example a silicon wafer containing a matrix of groups of circuit elements formed by diffusion and/or epitaxial deposition steps has a genetic oxide passivating layer. After aperturing this at desired contact areas a 20,000 A layer of molybdenum is deposited overall by sputtering, sublimation, or preferably the evaporation technique described in Specification 1,104,504 and pattern-etched to form the first level of interconnections. Then insulation such as silicon nitride, alumina, tantalum oxide, organic material or preferably silica is deposited e.g. by R.F. sputtering to a thickness of 10,000 A and etched to expose points to be joined to a second level of interconnections. Finally this second level is formed by depositing first 1200 A of molybdenum and then 7500 A of gold and pattern-etching. Normally the first level of interconnections are internal to one group of elements while the upper level interconnects the groups and has gold terminal wires bonded to it. In a modification, in forming the first level interconnections, gold is deposited over the molybdenum and after pattern-etching is removed save at the points of connection to the upper level. Then the exposed surface of the molybdenum is oxidized by briefly heating in oxygen before the inter-level insulation is deposited. In all cases ohmic contact to the semi-conductor surface is improved by diffusing impurities or forming deposits of aluminium or platinum silicide in the contact holes before depositing the molybdenum. The gold and molybdenum may contain adhesion improving additives (e.g. platinum in gold). |
