Diffusion mechanism of fluorine in plasma processing of III–V semiconductor compounds

Abstract

III–V semiconductors have attracted attention as high mobility channel materials in advanced metal oxide semiconductors. However, there is a possibility that their characteristics deteriorate owing to the damage caused by dry etching when processing the channel material. We focus on dry etching damage to InP and investigate the diffusion and injection of various elements. Secondary ion mass spectrometry (SIMS) shows that a fluorine atom can easily diffuse into the III–V semiconductor. Furthermore, we investigate the diffusion depths of other elements to determine the activation energies by using first-principles calculations. The SIMS results show the diffusion distance in the bulk InP is strongly correlated with the activation energy. Additionally, radicals containing F can easily diffuse into InP. Therefore, the number of radicals present in the gas phase of the plasma is important. An increase in the adsorption probability of the surface, owing to ion bombardment and knock-on phenomenon, is assumed.