WEP (www.wepcontrol.com) is currently supplying the electrochemical CV Wafer Profiler CVP21 (www.wepcontrol.com/cv-profiler) to the IHT at the Technical University of Braunschweig (http://www.iht.tu-bs.de ). At this location, there is profound experience with the full range of semiconductors, which includes Group IV semiconductors as Silicon, Germanium, SiC, III-V semiconductors as Arsenides, Phosphides, Antimonides, Nitrides, and II-VI semiconductors as ZnO.
Dr. E. Peiner from IHT comments: “We still operate an older PN4200 semiconductor profiler. After seeing the CVP21 in operation, I was very impressed by the enhancements of this new equipment.“
The CVP21 can be used directly after the epitaxial growth without any need of sample preparation. Measurements can be performed on large wafer samples, up to 8 inch diameter, but only a local spot of 1mm² or 10mm² is locally etched. It is no problem for the equipment to measure also small-sized samples down to 4*2mm. The handling of the water based electrolytes is completely automated - the measurement runs completely computer controlled without any operator influence. At the end of the measurement process the local etch spot is washed and dried automatically with nitrogen, so - except the 1mm² / 10mm² etch spot - the complete area of the wafer is available for further processing.
The CVP21 can be used to check the doping of layers, to check doping gradients and to check the quality of layer interfaces – also in hetero-structures. The carrier concentration as measured by ECV profiling calculates from the variation of the capacitance against applied voltage, on the dielectricity of the semiconductor layer and on the measurement area – so in advantage to Hall effect measurements no phenomenological constants are needed. Including a fully digitized admittance analysis, the capacitance variation can be measured with very high reliability over many orders of magnitudes without the need of external calibration standards.