A New Evaluation Technique Of Plasma-induced Si Substrate Damage By Photoreflectance Spectroscopy

Abstract

In this study, the Si substrate damage induced by the O2 plasma exposure is investigated by photoreflectance (PR) spectroscopy for the first time. The PR signal intensity from the Si surface with the plasma exposure is found to decrease at a typical photon energy, although the Raman spectroscopy does not show an apparent change for the damaged samples. The decrease in the PR signal intensity is attributed to the penetration of oxygen into Si substrate which is considered to be the carrierrecombination center at the vicinity of Si surface. The effect of the plasma exposure on the Si band structure is also discussed on the basis of the PR spectroscopic method. particular, compound semiconductors, by measuring the change of the reflectance of a semiconductor surface potential induced by the field due to the optically generated carriers.[7][8] Since the wavelength in PR spectroscopy is usually in the visible range, the PR spectroscopy gives the information dominantly from the surface region of materials, by taking into account the skin depth of the incident light. Moreover, from the PR spectrum, the electronic state in the material is determined. The purpose of this paper is to apply the PR spectroscopy to the evaluation of the Si surfaces damaged by 02 plasma exposure, and to discuss on the obtained result, including the electrical characteristics.