Resonant accelerometer with low sensitivity to package stress

A method of fabricating a microelectromechanical (MEMS) resonant accelerometer comprising:

• providing a substrate;
• forming on said substrate a proof mass having a central opening extending through said proof mass, an anchor located at a center of said central opening so that said proof mass is positioned generally symmetrically about said anchor, and suspension beams residing in said central opening, each of said suspension beams having one end affixed to said anchor and having another end attached to said proof mass at an inner peripheral wall of said opening;
• and
• performing a timed etch process to release said suspension beams and said proof mass from said substrate.

A resonant accelerometer comprising:

• a substrate;
• an anchor formed on a surface of said substrate;
• a proof mass positioned in parallel spaced apart relationship above said surface of said substrate, said proof mass having a central opening extending through said proof mass, said proof mass being positioned generally symmetrically about said anchor;
• suspension beams residing in said central opening, each of said suspension beams having one end affixed to said anchor and having another end attached to said proof mass at an inner peripheral wall of said central opening, said suspension beams including:
• first and second beams having respective first longitudinal axes that form a first common axis through said proof mass;
• and
• third and fourth beams having respective second longitudinal axes that form a second common axis through said proof mass, said second common axis being perpendicular to said first common axis.