SEMICONDUCTOR DEVICES

摘要

1,253,902. Schottky diodes. INTERNATIONAL BUSINESS MACHINES CORP. 25 June, 1969 [27 June, 1968], No. 31974/69. Heading H1K. A Schottky diode comprises a substrate carrying an epitaxial layer of one conductivity type less than 2À5Á thick and doped to an extent of less than 5 x 1016 atoms/c.c. A heavily doped inclusion of the same type is formed in the layer adjacent its interface with the substrate, and the Schottky contact on the layer opposite the inclusion. An integrated circuit comprising such a diode connected across the collector junction of a transistor is formed as illustrated in Fig. 1. N+ regions are formed in a 15 ohm./ cm. P type silicon substrate by oxide-masked diffusion and extended upwards by heating the subsequently deposited epitaxial layer 13. Then in successive masked diffusions transistor base zone 20, P+ isolation walls 18, 19, N+ surface contact regions 16, 17 and emitter zone 22 are formed. Next a silicon oxide or nitride passivating layer 23 is apertured as shown and platinum vapour deposited overall. After heating to alloy it in the apertures unalloyed platinum is etched away and a further thicker layer of aluminium or molybdenum deposited overall and pattern etched to form the connections shown to the emitter, between the transistor base and diode anode 20, 28a and between the transistor collector and diode cathode 14, 15. If the Schottky diode is required to have a higher forward voltage threshold its aperture is formed immediately before deposition of the molybdenum. The deposited cathode-collector connection and isolation walls are dispensed with in a simpler arrangement where N+ inclusions 14, 15 are combined into a single region. Alternative Schottky contact materials are palladium, chromium, molybdenum and nickel and these may be deposited and the aperture for the contact formed by low temperature RF sputtering. Details of certain conventional processing steps are disclosed.