Second order temperature compensated piezoelectrically driven 23 MHz heavily doped silicon resonators with ±10 ppm temperature stability

We report quartz level temperature stability of piezoelectrically driven silicon MEMS resonators. Frequency stability of better than ±10 ppm is measured for 23 MHz extensional mode resonators over a temperature range of T = -40 ... + 85°C. The temperature compensation mechanism is entirely passive, relying on the tailored elastic properties of heavily doped silicon with a doping level of n > 1020cm-3, and on an optimized resonator geometry. The result highlights the potential of silicon MEMS resonators to function as pin-to-pin compatible replacements for quartz crystals without any active temperature compensation.