Reactions of Primary Organosilanes on Transition Metal Surfaces. Identification of the First Surface-Bound Silylynes

Abstract

Transition metal silicides have numerous applications in the microelectronics industry. Primary organosilanes (RSiH[sub 3]) are attractive alternative silicon sources for the synthesis of metal silicides, since many of these compounds are stable in air. A Pt(111) surface in an ultrahigh vacuum chamber (10[sup [minus]10] Torr) was treated with a 7 langmuir exposure of t-BuSiH[sub 3] at 105 K, and subsequent reactions of the silane were studied by temperature-programmed reaction spectroscopy (TPRS). Confirmation of the formation of surface silylyne species was obtained by reflection-absorption infrared (RAIR) spectroscopy. Methylsilane also dehydrogenates on Pt(111) surfaces to give a stable organosilylyne product. The present data reveal that the S-H bonds of primary organosilanes readily cleave on Pt surfaces. The number of Si-H bonds cleaved is dependent on the temperature and coverage, but by 250 K all three are cleaved to yield organosilylyne units. Like alkylidyne units, with which they are isoelectronic, the organosilylyne species are probably bound to 3-fold hollow sites. 18 refs., 2 figs.