SURFACE DAMAGE ASSESSMENT OF NANOMETER FINISH SUBSTRATES USING DIFFERENTIAL REFLECTANCE SPECTROSCOPY

Differential reflectance spectroscopy (DRS) is a comparative technique that measures the normalized difference in reflectivity between sampl es in the UV to near IR region of the spectrum. We apply the technique to gallium arsenide substrates that have undergone different processi ng treatment. Spectral features are observed that can be assigned to c ritical point energies of the band structure. It is suggested that the se features arise from strain in the crystal lattice and that DRS is a possible candidate for monitoring process-induced damage in substrate preparation.