Fiber optic sensor for substrate temperature monitoring

Abstract

The use of an optical fiber Fabry–Perot interferometric temperature sensor for monitoring substrate temperature in a rf sputtering system is demonstrated. The sensor head consists of a continuous length of single mode silica fiber which contains two internal mirrors a distance of 1.08 cm apart to form the interferometer cavity. The laser light source for the sensor is located outside the vacuum system and connected to the sensor head via a fiber optic feedthrough. The accuracy of the sensor was 0.05 °C in this experiment, but considerable improvement is possible with better signal averaging techniques. The fiber optic sensor provided substrate temperature information during rf plasma excitation, when a nearby thermocouple ceased to function due to electromagnetic interference.