Interaction of atomic hydrogen with the surface methyl group on Si(100) — removal of surface carbon

Abstract

The interaction of atomic hydrogen with an overlayer derived from methyl iodide on the Si(100) surface has been studied using Auger electron spectroscopy (AES) and temperature programmed desorption (TPD) mass spectroscopy. Efficient removal of surface iodine by reaction with atomic hydrogen is observed. However, experiments with large exposures of atomic hydrogen also show the depletion of surface carbon. In contrast to the almost non-activated behavior observed for the extraction of halogens by an Eley-Rideal process producing the hydrogen halides, the carbon removal rate decreases with increasing temperatures ( T > 450 K). The depletion of surface carbon by atomic hydrogen correlates well with H-etching on the Si(100) surface in which SiH 4(g) is evolved, and is shown to be due to CH 3SiH 3(g) production during H-etching. In addition, isotopic exchange of the deuterium from CD 3(a) with hydrogen atoms supplied from the gas phase is also observed; this is found to be the most rapid kinetic process for the interaction of atomic hydrogen with the surface methyl group on Si(100). Finally, the selectivity of the H-induced reaction for two types of adsorbates, the methyl group and the halogen, is discussed.