Piezo-actuated MEMS Resonator

An integrated circuit comprising:

• a die;
• a microelectromechanical systems (MEMS) device on the die, the MEMS device having a body configured to deflect or vibrate during operation of the integrated circuit, the body having a piezoelectric material layer and one or more layers of crystalline silicon, including at least one degenerately doped silicon layer, the MEMS device having at least one layer operable to act as an electrode, to produce a signal which is dependent on the deflection or vibration of the body;
• and
• wherein the piezoelectric material layer is characterized by a stiffness having a first turnover temperature and a locally-parabolic behavior adjacent the turnover temperature which is a first one of convex or concave, and wherein the one or more layers of crystal silicon are characterized by a stiffness having a second turnover temperature and a locally-parabolic behavior adjacent the turnover temperature which is a second one of convex or concave;
• and
• wherein the body is fabricated such that the first turnover temperature and the second turnover temperature are matched within a threshold, and such that a frequency variation of the signal as a function of an operating temperature of the MEMS device over a predetermined temperature range lies within a predetermined threshold.

An oscillator integrated circuit comprising:

• a die;
• a microelectromechanical systems (MEMS) resonator on the die, the MEMS resonator having a body configured to vibrate during operation of the oscillator integrated circuit, the body having a piezoelectric material layer and one or more layers of crystalline silicon, including at least one degenerately doped silicon layer, the MEMS resonator having at least one layer operable to act as an electrode, to produce a signal which is dependent on the deflection or vibration of the body;
• at least one electrical contact coupled to the electrode, to output a timing signal which is dependent on the frequency signal;
• and
• wherein the piezoelectric material layer is characterized by a stiffness having a first turnover temperature and a locally-parabolic behavior adjacent the turnover temperature which is a first one of convex or concave, and wherein the one or more layers of crystal silicon are characterized by a stiffness having a second turnover temperature and a locally-parabolic behavior adjacent the turnover temperature which is a second one of convex or concave;
• and
• wherein the body is fabricated such that the first turnover temperature and the second turnover temperature are matched within a threshold, and such that a frequency variation of the signal as a function of an operating temperature of the MEMS resonator over a predetermined temperature range lies within a predetermined threshold.

An oscillator integrated circuit comprising:

• a die;
• a microelectromechanical systems (MEMS) resonator on the die, the MEMS resonator having a body configured to vibrate during operation of the oscillator integrated circuit, the body having a piezoelectric material layer and two or more layers of crystalline silicon, including at least one degenerately doped silicon layer, at least one single crystal silicon layer and at least one polycrystal silicon layer, the MEMS resonator having at least one layer operable to act as an electrode, to produce a frequency signal which is dependent on the vibration of the body;
• at least one electrical contact coupled to the electrode, to output a timing signal which is dependent on the frequency signal;
• and
• wherein the piezoelectric material layer is characterized by a stiffness having a first turnover temperature and a locally-parabolic behavior adjacent the turnover temperature which is a first one of convex or concave, and wherein the one or more layers of crystal silicon are characterized by a stiffness having a second turnover temperature and a locally-parabolic behavior adjacent the turnover temperature which is a second one of convex or concave;
• and
• wherein the body is fabricated such that the first turnover temperature and the second turnover temperature are matched within a threshold, and such that a frequency variation of the signal as a function of an operating temperature of the MEMS resonator over a predetermined temperature range lies within a predetermined threshold.