Aluminum-Selective Chemical Vapor Deposition Induced by Hydrogen Desorption on Silicon

Abstract

We studied the influence of the chemical structure of silicon-hydride species on Al deposition rate in Al-chemical vapor deposition (CVD) employing dimethylaluminum hydride (DMAlH) on a hydrogen-terminated Si surface. It was revealed that the peak temperature of hydrogen desorption from Si–H2 and Si–H3 in TDS spectra coincides well with the peak temperature of the Al deposition rate. We found that thermal hydrogen desorption from dihydride and/or trihydride species induced the Al-selective deposition reaction. Monohydride is not useful for the deposition at 240–290°C because of its higher desorption temperature of 350°C. In the early stage of Al deposition, a lower density of Al nuclei on the NH4F-treated surface compared with that on the HF-treated surface suggests that Al nucleation occurred at step edges on which di- and trihydride species exit.