Advanced Contactless Analysis of Plasma-Induced Damage on Si by Temperature-Controlled Photoreflectance Spectroscopy

• Published in: Japanese Journal of Applied Physics 2011-08, Vol.50 (8), p.08KD03-08KD03-7
• Main Authors: Matsuda, Asahiko, Nakakubo, Yoshinori, Takao, Yoshinori, Eriguchi, Koji, Ono, Kouichi
• Format: Article
• Language: English
• ISSN: 0021-4922; 1347-4065
• DOI: 10.1143/JJAP.50.08KD03

We propose an advanced photoreflectance (PR) spectroscopy technique, for use as a method for the contactless analysis of plasma-induced damage (physical damage) on Si. Si wafers damaged by Ar plasma were placed on a measurement stage capable of sample cooling by liquid nitrogen. In comparison to the spectra at 300 K, the signal intensity at 90 K was increased by cooling. A spectral peak of a heavily-damaged sample was identified at 90 K, which was difficult at 300 K. Changes in the surface potential induced by plasma exposure ($\Delta V_{\text{s}}$) were calculated by analyzing the spectral parameters. Areal densities of trapped charges were estimated from $\Delta V_{\text{s}}$. The temperature dependence of the PR spectra was discussed, and the primary cause of the increase in signal intensity was attributed to the reduced electron--phonon interactions in a lower temperature range. The proposed technique expands the applicable range of PR-based damage analysis.