Semiconductor Measurement Technology: Method to Determine the Quality of Sapphire

摘要

Specular reflectance measurements were used in the quantitative characterization of sapphire and silicon surfaces. Residual polishing damage in sapphire surfaces can be easily detected by infrared miltiple reflectance measurements in the lattice-band region of sapphire, nominally 300 to 900/cm. Specular reflectance measurements in the ultraviolet, at a photon energy of 4.3 eV (corresponding to the X sub 4 - X sub 1 silicon transition), have been used for the surface characterization of bulk silicon surfaces and silicon films on sapphire. This measurement is sensitive to crystalline quality, polishing damage, and surface texture which cause light-scattering effects. The reflectance methods are fast, nondestructive, and can be used for quality control and research purposes. The reflectance methods were applied to the characterization of variously polished sapphire surfaces and to the characterization of heteroepitaxial silicon films grown on the substrates. The results of these measurements were correlated with various parameters of silicon-on-sapphire (SOS) devices fabricated in the silicon films. Measured device parameters include drain current, extrapolated threshold voltage, leakage current, and drain breakdown voltage. Most device data were automatically recorded using a special device test pattern and simple statistical data were computed for the various device parameters.