Nanometer-Scale Materials Contrast Imaging with a Near-Field Microwave Microscope

We report topography-free materials contrast imaging on a nano-fabricated Boron-doped Silicon sample measured with a Near-field Scanning Microwave Microscope over a broad frequency range. The Boron doping was performed using the Focus Ion Beam technique on a Silicon wafer with nominal resistivity of 61 Ohm.cm. A topography-free doped region varies in sheet resistance from 1000Ohm/Square to about 400kOhm/Square within a lateral distance of 4 micrometer. The qualitative spatial-resolution in sheet resistance imaging contrast is no worse than 100 nm as estimated from the frequency shift signal.