The first commercially viable terahertz ellipsometer created
Enables non-contact evaluation of wide-gap semiconductors!
A group of researchers under the leadership of Assistant Professor Takeshi NAGASHIMA (Institute of Laser Engineering, Osaka University) together with a group of researchers at Nippo Precision Co., Ltd. succeeded, by applying ellipsometry to terahertz spectroscopy, in creating a terahertz ellipsometer, the first commercially viable terahertz ellipsometer. Called the Tera Evaluator , this revolutionary terahertz ellipsometer will be on display at SEMICON Japan 2013 to be held at Makuhari Messe from Wednesday , December 4 through Friday , December 6 .
Terahertz spectroscopy technology has rapidly developed since the development in the late 1980s of terahertz time-domain spectroscopy, a technique in which the properties of a material are probed with short pulses of terahertz radiation. Because terahertz spectroscopy has made it possible to measure free carrier concentration and mobility in semiconductors in a non-destructive and non-contact manner, its industrial applications have been expected. However, the evaluation of certain materials with conventional terahertz spectroscopy technology has been problematic limiting its application.
In contrast, the terahertz ellipsometer developed by this joint group makes it possible to determine free carrier concentrations and mobility in semiconductors from the measured complex permittivity spectra. Heretofore, the extinction ratio of a polarizer in the conventional terahertz region was inadequate, lowering measurement accuracy of ellipsometry. However, this group developed a wire grid polarizer with a high extinction ratio, thereby succeeding in making possible the first commercialized terahertz ellipsometer. The terahertz ellipsometer they developed does not need to measure reference signals making it possible for researchers to measure complex permittivity spectra of samples in the terahertz region with a high degree of accuracy on the spot. Thus, the Tera Evaluator is suitable for non-destructive, non-contact in-line inspection on a production line.
The manufacture of electrodes in wide-gap semiconductors and high-permittivity materials and the evaluation of dielectric characteristics and electric properties with conventional contact methods are problematic. The Tera Evaluator has made non-destructive and non-contact inspection of advanced materials and devices possible. Thus, this technology stands to be used in a variety of applications.
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