Cryogenic optical profilometry for the calculation of coefficient of thermal expansion in thin films

摘要

This paper describes the development of a cryogenic optical profilometry system (COPS) for the measurement of material properties of thin films across a wide temperature range. A cryostat was machined and integrated with a Zygo NewView 600K optical profilometer. Curvature data were taken for a SiN_x thin film on a GaAs substrate from 300 K down to 95 K. From the curvature data, the coefficient of thermal expansion was calculated. The COPS was validated against a three-beam curvature technique, and demonstrated good agreement across the full temperature range from 300 K to 95 K.