Influence of phosphorus doping on the chemical etching rate of polycrystalline silicon films

The chemical etching of intrinsic and n-type poly-Si with phosphorus concentration 5×1018cm−3 in Cl2 environment is investigated. It is found that phosphorus doping increases formation and desorption of SiCl2 molecules. The activation energy of Si+Cl2→SiCl2 reaction for intrinsic poly-Si is equal to 1.73±0.24eV, and it decreases to 1.51±0.16eV when n-type poly-Si films are used. Meanwhile, the desorption activation energy of SiCl2 molecules for intrinsic poly-Si is equal to 1.86±0.16eV, and it decreases to 1.54±0.21eV when n-type poly-Si films are used. The etching-rate limiting process is determined using the calculated mean times of elementary processes.