Desorption activation energy of SiBr2 molecules according to steady-state approximation

Abstract

The chemical etching of intrinsic and n-type polycrystalline silicon in Br2 ambient is considered. The theoretically calculated dependences of silicon etching rates on pressure of Br2 molecules at different temperatures are compared with experimentally measured ones. The reaction and desorption activation energies are evaluated. It is found that activation energy of Si + Br2 → SiBr2 reaction for intrinsic silicon is equal to (1:82 ± 0:24) eV, and decreases to (1:45 ± 0:24) eV when n-type silicon films are used. Desorption activation energy of SiBr2 molecules for intrinsic silicon is equal to (1:94±0:17) eV, and decreases to (1:51±0:17) eV when n-type silicon films are used. Desorption of SiBr2 molecules is an etching-rate limiting process at high pressure of Br2 molecules.