Accurate heterodyne interferometric ellipsometer

作者：Watkins L R^*

来源：Optics and Lasers in Engineering, 2010, 48(1): 114-118.

DOI：10.1016/j.optlaseng.2009.08.002

• Ellipsometry
• Thin films
• Interferometry
• Optical metrology

We describe a heterodyne interferometric ellipsometer which requires only a single reflection from the sample surface. A simple arrangement is described that enables a reference beam to be created in one arm of a modified Mach-Zehnder interferometer such that the p- and s-polarisations in this arm have a common phase and fixed relative amplitude, irrespective of the sample. When this beam is recombined interferometrically with the measurement beam, the spatially separated p and s fringes have an amplitude ratio and relative phase that are directly proportional to tan psi and Delta, respectively. Adjusting the azimuthal angle of the input linear polarisation allows both psi-tracking to be implemented and error reduction through averaging. Measurements made with this instrument of a native oxide layer on a silicon substrate are in excellent agreement with those obtained using a commercial ellipsometer.

• 出版日期2010-1