Chemoical Vapor Deposotdoo of Tungsten and Molybdenum Folms From m(η³–C₃H₅)₄ (M=Mo, W)

Abstract

Chemical vapor deposition using tetra(allyl) tungsten and molybdenum precursors yielded amorphous tungsten and molybdenum carbide films on pyrex substrates. The films were characterized by Auger, ESCA, SEM, XRD and resistivity measurements. Volatile pyrolysis products consisted primarily of propene, C3H6.

Molecular Routes to Metal−Carbides, −Nitrides, and −Oxides. 3.1 Chemical Vapor Deposition Employing X3W⋮*CCMe3, Where X = CH2CMe3, OtBu, and OtBu-d9 and *C = 12C or 13C, and a Comparison with the Chemistry of (tBuO)3W⋮N

“…To stress the positive, use of (Me 3 CCH 2 ) 3 W⋮CCMe 3 provides a low-temperature route in the synthesis of WC films. Relative to the reactions employing Cp 2 WH 2 , (allyl) 4 W, (crotyl) 4 W, and CpW(CO) 3 X, where X = Me and H, which yield a mixture of WC and graphite (ca. 50:50), the success of (Me 3 CCH 2 ) 3 W⋮CCMe 3 may rest with its relatively high internal H to C content.…”

“…Tungsten carbide is, of course, one of the most important constituents of modern cemented materials due to its very high hardness and its exceptional inertness to chemical attack. Chemical vapor deposition employing precursors such as W(CO) 6 or WF 6 was known to give films of WC but only with high impurities of heteroatoms such as oxygen or halogens, while the use of organometallic compounds 12a-c such as (η 6 -C 6 H 6 ) 2 W, (allyl) 4 W, CpW(CO) 3 H, and Cp 2 WH 2 gave films with high graphite content. An ingenious attempt to reduce the latter was attempted by employing a trace amount of a volatile organoplatinum compound in the presence of H 2 gas whereby the Pt could assist in the hydrogenation of the unwanted carbon 12d.…”

“…Chemical vapor deposition employing precursors such as W(CO) 6 or WF 6 was known to give films of WC but only with high impurities of heteroatoms such as oxygen or halogens, while the use of organometallic compounds 12a-c such as (η 6 -C 6 H 6 ) 2 W, (allyl) 4 W, CpW(CO) 3 H, and Cp 2 WH 2 gave films with high graphite content. An ingenious attempt to reduce the latter was attempted by employing a trace amount of a volatile organoplatinum compound in the presence of H 2 gas whereby the Pt could assist in the hydrogenation of the unwanted carbon 12d. This approach met with some success but, of course, led to incorporation of Pt in the films.…”