Light scatter from polysilicon and aluminum surfaces and comparison with surface-roughness statistics by atomic force microscopy

Optical-scatter measurements from polysilicon and aluminum surfaces were performed by using 632.8-nm illumination at 45 deg and 488-nm illumination at 76.8 deg. Scatter was recorded up to 60 deg from the specular beam by using a concentric ring photodetector. The results are compared with surface statistics derived from atomic force microscopy. Quantitative predictions of the scatter were derived from power spectral density curves and angle-resolved-scattering theory. The agreement was fair for polysilicon samples with rms surface roughnesses of ~18 and 42 nm and aluminum with 17-nm rms roughness but poor for other samples. The discrepancy is attributed primarily to internal scatter within the measuring instrument.