Multilayer Thickness Determination Using Continuous Wave THz Spectroscopy

We present a multilayer thickness measurement system based on optoelectronic continuous wave THz spectroscopy. Due to its wide tuning range, high frequency resolution, and fast data acquisition the system combines micrometer precision with short measurement time. In addition, the presented system is not limited by the 2 pi uncertainty of previous continuous wave signals and is therefore capable of measuring thick layers. Thus, the presented system and measurement method are a cost effective alternative to THz time-domain systems in the field of thickness measurements.