Synchrotron X-ray topography of supercritical-thickness strained silicon-on-insulator wafers for crystalline quality evaluation and electrical characterization using back-gate transistors

We investigated the crystalline quality of supercritical-thickness strained silicon-on-insulator (SC-sSOI) wafers by synchrotron X-ray topography and its correlation with electrical characteristics by use of back-gate transistors. Several types of contrast showing crystalline imperfections were observed over the entirety of the wafers, such as macule and crosshatch patterns in X-ray topographs. From the analysis of a series of X-ray topographs obtained by changing the angle of incidence relative to the sample surface, we obtained two-dimensional distributions of lattice inclination and strain, indicating that the crosshatch patterns observed in the X-ray topographs were caused by fluctuation of the lattice inclination. Transistors located in an area of large lattice inclination deviated from the average drain current-gate voltage curves, showing a correlation between lattice inclination and electrical properties.