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 statastics 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 approximately 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.