Formation and bonding structure of silicon nitride by 20-keV N+ ion implantation

Abstract

The nitridation process and the annealing effects for Si‐nitride layers prepared by 20‐keV nitrogen ion implantation have been investigated by means of x‐ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). The surface layer of samples implanted at a low dose is composed of a mixture of elemental Si regions and Si‐rich nitride regions. A continuous near‐stoichiometric Si‐nitride is formed without annealing as the implantation dose is increased. Shifts of the XPS spectra (Si_2p and N_1s lines) toward higher binding energy with the implantation dose are observed. Similar shifts are also observed in AES spectra. The peak energy of the Si_2p line is connected with a weighted average coordination number at a Si site in the SiN_n (n=0,...,4) configuration, and the chemical shift per Si‐N bond is 1.0 eV. The shift of the N_1s line is interpreted in terms of a change in the short‐range order at an N site.