Development of substrate temperature monitoring system for high-accuracy plasma process

It is important to accurately measure and control the temperature of wafer in order to realize the reproducibility of the semiconductor devices at the atomic level.

Even though it is necessary in the semiconductor manufacturing process, an accurate measurement of the wafer temperature, performed using an optical interferometer ^(*), has been extremely challenging due to various disturbances from others devices, such as vibrations.

Having focused on a high degree of parallelism and high reflection of the wafer, Dr. Tsutsumi has proposed a novel approach to measure the temperature of wafers using the interference of lights reflected on front and back surfaces of the sample. His method, unlike the conventional one, uses a single path to drive the interfering light to the detector. His apparatus can consequently perform highly accurate temperature measurements with a strong robustness against vibrations.

This technique enables high-accurate and high-speed temperature monitoring of the wafer during the process. Thus, the great contribution for improving the yield of manufacturing processes can be expected.

* When a light beam is split from a single source and recombined hereafter, a phenomenon called “interference” occurs. The interfering light includes information such as the refractive index of a material or the length of the path that divided lights through.