MEMS resonators having resonator bodies therein with concave-shaped sides that support high quality factor and low temperature coefficient of resonant frequency

A concave bulk acoustic resonator (CBAR), comprising:

• a substrate:
• a resonator body suspended over the substrate by a pair of fixed supports that attach to first and second opposing ends of said resonator body, said resonator body having a first concave-shaped side extending between the first and second ends of said resonator body and a second concave-shaped side extending opposite the first concave-shaped side;
• a drive electrode extending adjacent the first concave-shaped side;
• and
• a sense electrode extending adjacent the second concave-shaped side;
• wherein a width of the drive electrode as measured along the first concave-shaped side is less than a spacing between the first and second ends of said resonator body.

A concave bulk acoustic resonator (CBAR), comprising:

• a substrate;
• a resonator body suspended over the substrate by a pair of fixed supports that attach to first and second opposing ends of said resonator body, said resonator body having a first concave-shaped side extending between the first and second ends of said resonator body and a second concave-shaped side extending opposite the first concave-shaped side;
• a piezoelectric layer on said resonator body;
• a first electrode extending across a first of the pair of fixed supports and onto said piezoelectric layer;
• and
• a second electrode extending across a second of the pair of fixed supports and onto said piezoelectric layer.