PHILIPS ELECTRONIC ASSOCIATED INDUSTRIES LTD METHODS OF APPLYING METAL CONTACTS TO SEMICONDUCTOR BODIES

摘要

1323136 Semi-conductor devices PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd 23 Sept 1970 [26 Sept 1969] 45340/70 Heading H1K A N-type Si wafer 1, Fig. 3, carries an N-type epitaxial layer 2 overlain by a thermally oxidized Si layer 3. After grinding a Ni layer 4 is electroless plated on the remote side and heated to establish low ohmic contact. Square apertures are etched in oxide layer over photoresist and the surface is vapour-deposited with a Ni layer 6 lying partly on the oxide layer and partly on the exposed epitaxial Si to establish rectifying Schottky contacts. The structure is subjected in a water bath to high power high frequency acoustic vibrations removing the Ni layer overlying the oxide and leaving it adherent to the Si and a further nickel layer is applied to layer 4, Fig. 4. The wafer is scribed and broken into diodic portions enclosed in glass envelopes Fig. 5, and soldered to base 10 with layer 6 contacted by Mo whisker pressure contact 9. The wafer may be connected to a support during acoustic treatment which may be conducted otherwise than in water. In fabrication of a switching diode (Figs. 6-10, not shown), the Si exposed in the windows may be etched away by HF + HNO 3 to undercut the oxide layer, and Pt may be sputtered on to the surface to establish Schottky contacts with the epitaxial layer and heated in N + H to promote adhesion. The acoustic treatment removes the Pt and the protruding oxide edges to obtain separate Schottky contacts, and the several diodes are separated by scribing and breaking and fitted into envelopes. Au and Pd and Ti may be used for contacts and Ge or IIIb-Vb compounds for semi-conductor, while the insulant layer may be Si 3 N 4 or Al 2 O 3 . The method is applicable to non-rectifying semi-conductor contacts. Adherent metal strip connections of, e.g. Cr or SiO 2 applied to the insulant layer may replace whisker connections.