Chemical etching of Si(111)‐(7×7) and Al/Si(111) by atomic hydrogen

We have observed an etching reaction on the Al/Si(111) surface (θ_Al≥1) induced by the chemisorption of atomic hydrogen at low temperature (T=250–400 K). The major silicon containing product detected by temperature programmed desorption (TPD) is silane (SiH₄). An approximate sixfold increase in silane production is observed in the presence of aluminum, with a decrease in the TPD peak temperature from 645 K on Si(111) to 335 K on Al/Si(111). A kinetic model is presented to explain this catalyzed etching reaction.