THE CHEMISORPTION OF H2C[SI(CH3)(3)](2) AND SI-6(CH3)(12) ON SI(100) SURFACES

The chemisorption of bis(trimethylsilyl)methane (BTM, CH2[Si(CH3)(3)]( 2)) and dodecamethylcyclohexasilane (DCS, Si-6(CH3)(12)) on clean Si(1 00) surfaces has been studied by C 1s core-level and valence-band phot oemission spectroscopy. Our model for the deposition of carbon by BTM involves decomposition into a -CH2Si(CH3)(3) surface moiety for room-t emperature adsorption, which further decomposes upon annealing to 550 degrees C to form a surface terminated primarily by CHx units. DCS dep osits almost three times as much C on the surface as BTM. The data are consistent with DCS undergoing a ring opening and bonding to the surf ace as polydimethylsilane chains. Annealing both adsorbates to 950 deg rees C causes a large decrease in the C is signal due to the fact that Si segregates to the surface at temperatures above 900 degrees C. The valence-band photoemission of Si(100) dosed with DCS at 950 degrees C is in good agreement with that of beta-SIC, whereas the analogous BTM spectrum deviates significantly.