Plasma Deposition of Amorphous Metal Alloys

Rapid solidification, sputtering and electroless chemical deposition have been used to produce amorphous metal alloys which possess excellent corrosion and abrasion resistance. This paper discusses a new technique for obtaining amorphous metal alloy coatings. This technique consists of dissociating mixtures of organometallics (metal carbonyls) and metalloid hydrides in a hydrogen carrier gas using a radio-frequency discharge. In particular, the formation of Ni-P alloys is discussed.Plasma decomposition of Ni(CO)4 and PH3 in argon and hydrogen carrier gases [Ni(CO) 4/PH3˜8/l] yielded films that were black and silver, respectively, in appearance. Both films were amorphous as determined by transmission electron microscopy. Films deposited using a hydroqen carrier gas were three orders of magnitude more conductive than those deposited using an argon carrier gas. Analysis of both films using electron microprohe analysis and inductively-coupled plasma spectroscony showed an enrichment of P in the films over the P content in the plasma qas mixtures. Reducinq the P content of the plasma gas mixture [Ni(CO)4/PH3˜17/Il yielded crystalline films with no P enrichment. The grain size in these films was ˜Å as determined by x-ray line-broadeninq.Using Auger electron spectroscopy, films deposited using hydroqen and argon carrier gases were determined to have, in addition to Ni and P, small amounts of carbon (8–12 at%) and oxygen (1–4 at%). Infrared spectra of both crystalline and amorphous films showed chemisorhed CO.