A SSIMS and TPD Study of tert-Butylacetylacetate Adsorption on Si(100)

Adsorption and decomposition of tert-butylacetylacetate (tBAA) on Si(100) have been investigated using static secondary ion mass spectrometry and temperature-programmed desorption. At low doses, all tBAA molecules dissociate readily upon adsorption on the surface at temperatures as low as −160 °C. The dissociation may occur through tBAA bonding via the ester oxygen or the carbonyl group to the surface. The bond scission occurring at the tBuO−CO bond leads to the formation of surface tert-butoxide. Further dehydrogenation can take place to yield isobutene and surface hydroxyl species. Subsequent heating of the substrate causes the hydroxyl to decompose, and the resulting substoichiometric silicon oxide sublimes as SiO. The surface-induced bond scission also occurs at the OC−CCO bond of the tBAA diketo moiety to produce isobutene. In addition, the OC−CCO bond scission induced by tBAA surface bonding, mainly via its carboxylic keto oxygen, affords acetaldehyde radical, whereas that induced mainly via the ace...