A silicon micromachined scanning thermal profiler with integrated elements for sensing and actuation

The thermal profiler is a scanning probe microscope with a miniature thermocouple (TC) at its tip which provides topographic and thermographic information by sensing heat conducted across a small air gap. The silicon micromachined thermal profilers (SMTPs) described in this paper are structurally comprised of a probe that can be longitudinally actuated by an integrated electrostatically driven suspension. A polysilicon-gold TC is located near the probe tip, which overhangs a glass substrate; a resistive heater is integrated with the base. An IC-compatible, 8-mask fabrication process has been developed and SMTPs with various types of frames and probes have been designed, fabricated, and thermally characterized. The maximum thermoelectric signal available from a 7-TC thermopile probe has been measured at 824 mV/W of input power to the heater, whereas from a simpler design it was 48 mV/W. Simple dithered and nondithered scans are presented to demonstrate the basic functionality of fabricated devices. The noise due to our test setup has been measured at ≈20 mK. For a 1 μm×0.5 μm tip and a 0.1 μm long air gap the spatial resolution and the device NETD have been theoretically estimated as ≈3.33 nm and ≈0.1 mK/√Hz, respectively