| 摘要 |
968,090. Semi-conductor devices. PHILCO CORPORATION. Feb. 7, 1961 [Feb. 26, 1960], No. 4526/61. Heading H1K. In a semi-conductor device such as a Si transistor, a high temperature resistant ohmic joint between a Si body and a metal element is produced by using Pt and Ni as bonding agents. As shown, a Si wafer 1 is placed on a support 4 of graphite-coated alumina in overlapping relation with a base tab 2 of Mo, the surface of which adjacent the Si wafer is electroplated with layers of Pt and Ni, the latter containing a significant impurity, such as B or P, characteristic of the conductivity type of the wafer. Bonding is effected by heating, if desired in an inert, e.g. A, atmosphere, at a 1000‹ C. for 10-15 sees., by passing current through tab 2 via two W probes 7, 8 bearing on the tab. Before the bonding step, the Si wafer is dipped in HF acid, rinsed in de-ionized water, and dried, and the tab is cleaned in concentrated H 2 SO 4 . The tab, which may alternatively be of Ta, W, or Nb, is preferably given two strike coats, one of Cr and one of Ni, before the Pt layer is applied in a known Pt bath. The impurity-containing Ni coat is then applied. A Ni-B bath comprises NiSO 4 .6H 2 O-300 g./l.; NiCl 2 .6H 2 O-60 g./l.; H 3 BO 3 -38 g./l. ANi-P bath comprises NiSO 4 .6H 2 O-175 g./l.; NiCl 2 . 6H 2 O-50 g./l.; H 2 PO 4 -50 g./l.; H 3 PO 3 - 1.3 g./l.; plus 14 g. NiCO 3 neutralized with c. 50 g. H 3 PO 4 . Cladding or deposition by thermal evaporation may be employed instead of electroplating. |
