Al Photodeposition and Light-Induced Nucleation on p-Type Si from TMA

Abstract

ABSTRACTPhotodecomposition of trimethylaluminum (TMA) flowing with H2 on p-type Si under UV irradiation is shown to be exclusively a reaction confined to surface species. Thus photonucleation and photodeposition of Al on Si is controlled either by Si-H or Si-O and Si-OH bonds. In the regions where Si-O and Si-OH are present, Al-O forms, which inhibits Al deposition either directly or via the adsorption of C containing photoproducts. In the other regions where Si is H terminated, it is assumed that H2 adsorbs dissociatively on Al clusters, thus leading to the formation followed by the desorption of methane from the adsorbed phase. For this reason, Al thin films are C contamination free.