In the semiconductor industry, infrared <answer>light</answer> can be used to characterize materials such as thin films and periodic trench structures. By measuring the reflectance of <answer>light</answer> from the surface of a semiconductor wafer, the index of refraction (n) and the extinction Coefficient (k) can be determined via the Forouhi-Bloomer dispersion equations. The reflectance from the infrared <answer>light</answer> can also be used to determine the critical dimension, depth, and sidewall angle of high aspect ratio trench structures.
What reflectance is measured from a semiconductor wafer's surface to determine the index of refraction?
light