Evaluation of surface and bulk qualities of semiconductor materials by a laser-induced photothermal technique

Non-destructive evaluation of defects for semiconductor materials is critical to the quality control process. The existing evaluation methods, including radiographic testing, ultrasonic detection, fluorescence and infrared imaging, are widely used in industrial applications. In this paper an instrument based on laser-induced photothermal technique was applied to study various semiconductor materials. With a specially arranged pump-probe configuration, this system can do three dimensional mapping of local properties and defects. By using this photothermal instrument, several semiconductors, such as bulk CdZnTe (CZT) crystals and monocrystalline silicon wafers under different processing conditions, were investigated. The surface and internal structures and defects of these materials were tested nondestructively by the 3-D photothermal microscope. The results show intersting correlation between the photothermal characterizations and the processing conditions. In addition, the details of the development of the 3-D photothermal microscope were also presented. The system provides user-friendly operations of the defects characterization process and shows great potential of application for characterization of semiconductor materials.