Characterization of Epitaxial Layers and Ion-Implanted Surfaces on Semiconductor Wafers by Scattering of Light and Optical Surface Waves

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Since surfaces of semiconductor wafers are most important for electronic devices, epitaxial growth and ion-implantation on them are keys to open doors for new intelligent devices by producing suitable perfection and conductivities.Here new methods were developed to detect and characterize defects in and on the epitaxial layers and ion-implanted regions by light scattering techniques.1. Optical surface waves are generated by the condition deviated slightly from the critical reflection at the surface, which propagate along the surface. The scattering caused by flaws and scratches. By the incident angle against the surface which is a little smaller than the angle for the surface waves, a guided waves will propagate inside the epitaxial layers or wafers as a guided wave.2. This phenomena was very effective for characterization of wafers when a laser beam can be impinged from the backside of wafer at the condition mentioned above or when both side of wafers were polished as mirrors. Unfortunately, most of wafers for devices are roughened by sandblast or metallized and then the other method will be developed for those wafers, where the laser beam will be impinged into the wafers from mirror polished top surface.3. The radiation damages caused by implanted-ions act as centers of Rayleigh scattering, which are detected by transmitted as well as by reflected light, clearly. The scattering from the damaged region will be detected and semi-quantitatively measured if the dose amount is more than 10 B 12. Here, detection and measurement are done from the top surface of wafers, which will be nicer than the other ordinary ways.