A major challenge of in-situ metrology on single-port reactors with small viewport geometries is the combination of curvature measurements by a blue laser with reflectance measurement at 405 nm. The blue laser is a must for patterned sapphire substrates (PSS) and double-side polished substrates.  The 405 nm reflectance is indispensable for monitoring of InGaN MQW growth. Until now, it was impossible to have both features for reactors with only one small optical access because of the cross-talk effect. The new optical and electronic design of EpiCurve® TT eliminates this problem.

Fig. 1: EpiCurve® TT used in Magdeburg, Germany

The latest version of the tool has been installed on an Aixtron 200-4 RF/S reactor with only 5 mm hole in the ceiling at Otto-von-Guericke University of Magdeburg (Germany). The team of Prof. Alois Krost and Prof. Armin Dadgar uses the tool in development projects for in-situ monitoring of various GaN based optoelectronic and power electronic device structures on silicon and sapphire substrates. This Epi-Curve® TT is equipped with a blue laser (405 nm) for wafer bow control and a triple wavelength reflectance (405, 633 and 950 nm) for a precise monitoring of MQW layers, AlN interlayers, AlGaN buffer and further features.

After several years of experience with LayTec systems, Prof. Krost is convinced that “EpiCurve® TT is the best in-situ tool available on the market to control strain, temperature uniformity, MQW formation and surface morphology during III-N device growth.“ LayTec CTO Dr. Kolja Haberland thanked the team in Magdeburg for the long year research cooperation and for testing the new product in the field.