Effect of oxygen agglomeration in polycrystalline Si (SIPOS) films

IR transmission spectra of SIPOS structures were measured and were investigated by using an approach of deconvolution of the Si–O stretching band into Gauss profiles. It was found that the space distribution of oxygen in SIPOS layers treated at elevated temperatures does not correspond to the prediction of RBM statistics. The oxygen agglomeration was observed. Optical microscopy was also applied to get additional information about the SIPOS films after treatment in HF solution. The peculiarities of the space distribution of oxygen in SIPOS films are explained on the basis of a computer simulation of free Si surface relaxation. A computer model has shown that a disordered phase arises in the Si surface layers at elevated temperatures. This phase is characterized by a large concentration of stressed and dangling bonds. There are lattice nodes with more than one dangling bond that are suitable sites for oxygen agglomeration.