Photoreflectance characterization of the plasma-induced damage in Si substrate

Si surface damage induced during Ar and CHF3/CF4/Ar plasma processing has been characterized by photoreflectance spectroscopy (PRS). The photoreflectance (PR) signal intensity decreases drastically as the rf input power increases in the Si substrate exposed to the plasma. The recovery of the plasma-induced damage is confirmed by PRS after subsequent annealing over 500 degrees C. We found, from the shift of the PR spectra, the strain at the Si surface induced by the plasma treatment might be due to the introduction of the ions, C, F, or H, not to those of Ar. The depth profile of the defect density in the Si substrate is estimated quantitatively by analyzing the depth profile of the PR signal intensities. (C) 2000 American Institute of Physics. [S0021-8979(00)06316-7].