Infrared (IR) pyrometry
Yield improvement through temperature uniformity
Wafer temperature is one of the key parameters during epitaxial growth. It influences the growth rate, the composition of ternary and quaternary compounds and the doping level. Wafer temperature also has an important impact on the quality of the grown layer and its roughness, thereby influencing the performance of devices based on such epitaxial layers. As a result, careful monitoring and precise control of wafer temperature throughout the entire growth process are indispensable.
Problem: Insufficiency of conventional pyrometry
Conventional pyrometry measurements on heterostructures without emissivity correction show oscillations due to interference effects. To see the true temperature (TT), LayTec metrology solutions combine two methods:
- intensity measurement of thermally emitted light
- normal incidence reflectometry
We call this Emissivity Corrected Pyrometry (ECP). This screenshot demonstrates the difference between the uncorrected temperature (blue) and the True Temperature (TT) measured by the method of ECP.