A parametric study on surface roughness evaluation of semi-conductor wafers by laser scattering

Abstract

A technique for measuring surface roughness of semi-conductor wafers in the nanometer range has been developed. The principle of the method is based on laser scattering from a rough surface. A tele-centric optical set-up is constructed to illuminate the test specimens and the scattered light field is recorded with a photo-diode sensor connected to a digital amplifier. A parametric method is proposed for the evaluation technique and results obtained are compared with those obtained using a conventional Taylor Hobson mechanical stylus profilometer. A set of roughness standards fabricated in accordance with BS 2634 and ISO 2632 is employed in the calibration process.