Aufbau eines Ultraschall-Mikroskops zur Charakterisierung der Degradation von Halbleiterschichten

Nondestructive testing with acoustic microscopy plays a significant role in the quality control of the semiconductor industry. With modern test procedures semiconductors are tested for material defects. With measurement methods components are stressed by a transient, electrical pulse for the detection of degradations. In the semiconductor industry these stress tests are often performed outside the acoustic microscope for safety reasons, whereby measurement methods are getting more time-consuming or are even not practical anymore. The development of an acoustic microscope for testing of semiconductors which are stressed while the microscope is operating is described. Measurements, including the ultrasound testing and the excitation of the semiconductor, are taken automated. The components of the system are chosen in a way that the lateral resolution and the overall time for a measurement meets the typical values of ultrasound tests in today's semiconductor industry. A design of an acoustic microscope fulfilling these requirements is presented. Beside the characterization of the microscope this thesis presents two applications for the system: the detection of a gradual degradation of a semiconductor dependent on transient, electrical pulses and the detection of thermomechanical strain inside a semiconductor. These two applications are realized and the results are presented.The circulation of the project work is restricted from dd.mm.2015 for a period of 5 years.