All-dielectric micromachined calorimeter for high-resolution microwave power measurement

We have developed a micromachined bimaterial cantilever with a thin-film ferromagnetic resonance (FMR) sensor to probe rf fields near microwave devices. A patterned permalloy film deposited at the tip of the cantilever serves as the localized FMR probe. Power absorption at the tip, under FMR conditions, results in a proportional bending of the bimaterial cantilever. The deflection of the cantilever is measured with an optical lever. The small dimensions of the probe (20 mum x 20mum x 0.05mum) allows for measurements of rf magnetic fields near microwave devices with 20 mum resolution and minimal intrusion. The sensor is constructed of low-stress silicon nitride and low-temperature-deposited silicon oxide The use of dielectric materials in the cantilever beam minimizes the background signal produced by eddy-current heating of the cantilever. Using this scanning FMR probe we have measured vector-component-resolved microwave field distributions near a 500 mum wide stipline resonator driven at 9.15 GHz.