Visualization of Plasma Etching Damage of Si Using Room Temperature Photoluminescence and Raman Spectroscopy

Room temperature photoluminescence (RTPL) and Raman spectroscopy were used for characterizing plasma-induced-damage (PID) of Si during plasma assisted Si processing. Oxide films with thicknesses of similar to 200 and similar to 600 nm were grown on 300 mm wafers by plasma enhanced chemical deposition (PECVD). Bare Si wafers with native oxide and PECVD oxide films were plasma etched under different etching and bias radio frequency (RF) power conditions. Oxide etch rate, oxide uniformity and RTPL spectra/intensity were measured and characterized under three excitation wavelengths (532, 650 and 827 nm) with different probing depths. High spectral resolution Raman measurements were performed under various excitation wavelengths from the ultraviolet (UV) to visible (VIS) region to verify the distribution of plasma etching damage in the depth direction as a function of plasma etching condition and structure of specimens. A distinct pattern of PID, corresponding to showerhead patterns, common to a typical plasma etching system, was observed from RTPL wafer mapping results. Multiwavelength Raman characterization revealed that the physical damage to the Si crystalline lattice, from plasma etching, was concentrated at, or near, the Si surface and SiO2/Si interface. Identification and characterization of PID were successfully done by using multiwavelength RTPL and Raman spectroscopy. (C) 2013 The Electrochemical Society.