Piezo-actuated MEMS resonator

A method of manufacturing an integrated circuit, the method comprising:

• providing a microelectromechanical system (MEMS) resonator on the integrated circuit;
• wherein providing comprises forming the MEMS resonator to have a degenerately doped single-crystal silicon (SCS) layer, a piezoelectric material layer disposed on the degenerately doped SCS layer, and an electrically conductive layer disposed on the piezoelectric material layer opposite the degenerately doped SCS layer, wherein the integrated circuit is to provide an output dependent on a resonance mode of the MEMS resonator;
• and
• wherein forming the MEMS resonator comprises configuring the degenerately doped SCS layer to have a dopant concentration and crystal orientation relative to an axis of vibration of the resonance mode such that the degenerately doped SCS layer has a second order temperature coefficient of frequency (TCF) that is opposite in sign to the second order TCF of the piezoelectric material layer.

An integrated circuit comprising:

• a microelectromechanical system (MEMS) resonator on the integrated circuit;
• the MEMS resonator having a degenerately doped single-crystal silicon (SCS) layer, a piezoelectric material layer disposed on the degenerately doped SCS layer, and an electrically conductive polycrystal silicon layer disposed on the piezoelectric material layer opposite the degenerately doped SCS layer;
• circuitry to sense a temperature;
• circuitry to receive a signal from the MEMS resonator dependent on a resonant frequency of the MEMS resonator and to generate an output dependent on the resonant frequency and the sensed temperature, in a manner such that the output exhibits a reduced temperature dependent variation relative to temperature-dependent variation of the resonant frequency;
• wherein the piezoelectric material layer has a second order temperature coefficient of frequency (TCF) and the degenerately doped SCS layer is configured to have a dopant concentration and crystal orientation relative to an axis of vibration of the resonance mode such that the degenerately doped SCS layer has a second order TCF that is opposite in sign to the second order TCF of the piezoelectric material layer;
• and
• wherein a ratio of a thickness of the degenerately doped SCS layer to a thickness of the piezoelectric material layer is selected such that a first order TCF of the degenerately doped SCS layer is opposite in sign to a first order TCF of the piezoelectric material layer and such that an overall first order TCF of the MEMS resonator lies within a predetermined tolerance range about zero.