Quantitative Imaging of Sheet Resistance with a Scanning Near-Field Microwave Microscope

We describe quantitative imaging of the sheet resistance of metallic thin films by monitoring frequency shift and quality factor in a resonant scanning near-field microwave microscope. This technique allows fast acquisition of images at approximately 10 ms per pixel over a frequency range from 0.1 to 50 GHz. In its current configuration, the system can resolve changes in sheet resistance as small as 0.6 Ohms/sq for 100 Ohms/sq films. We demonstrate its use at 7.5 GHz by generating a quantitative sheet resistance image of a YBa2Cu3O7 (YBCO) thin film on a 5 cm-diameter sapphire wafer.