Kelvin probe force microscopy on corona charged oxidized semiconductor surfaces

We present results demonstrating that Kelvin probe force microscopy (KPFM) can be used with high accuracy for corona charge aided oxide thickness mapping. In our experiments, corona charge layers of varying density were deposited onto the surface of thermally oxidized silicon wafers with different oxide thicknesses. After deposition, the surface potentials of the samples were characterized using both the standard Kelvin probe method and KPFM. Comparison of the surface potentials measured by both techniques showed that the values are in excellent agreement, and that only insignificant discharging of the corona charge layer occurred during the topography scan necessary in KPFM measurements.