MEMS teeter-totter accelerometer having reduced non-linearty

A force sensing device comprising:

• a frame;
• a proof mass surrounded by the frame and suspended therefrom for out-of-plane rotation on a pair of torsional flexures positioned substantially intermediate of a length dimension of the proof mass;
• and
• first and second pluralities of capacitors formed between a first plurality of comb teeth formed on exterior peripheral edges of the proof mass and a cooperating second plurality of comb teeth formed on interior peripheral edges of the frame, the first and second pluralities of capacitors being spaced symmetrically about a center of rotation of the proof mass.

A method for fabrication of a capacitive comb tooth sensor having substantially symmetrical differential signal detection, the method comprising:

• in a substrate formed of semiconductor silicon material and having first and second opposing substantially parallel spaced-apart planar surfaces, forming a substantially rectangular pendulous mechanism proof mass structure having a plurality of capacitive comb tooth sensors spaced symmetrically about a computed center of rotation thereof, with first and second endwise groupings of the comb tooth sensors being positioned along each of respective opposing first and second end portions of the proof mass distal from the center of rotation, and first and second lateral groupings of the comb tooth sensors being positioned along each of respective extreme side portions of the proof mass adjacent to each of the opposing end portions and spaced away from the center of rotation with central zones of each of the side portions being devoid of the comb tooth sensors;
• in the substrate, forming a frame structure having a substantially rectangular aperture surrounding the proof mass and spaced therefrom;
• in the substrate, forming one or more flexures between the proof mass and the frame positioned substantially intermediate of a length dimension of the proof mass, the one or more flexures being structured for out-of-plane rotation of the proof mass relative to the frame about a rotational axis that passes through the computed center of rotation;
• and
• in the substrate, forming a plurality of comb teeth in first and second endwise groupings along respective first and second endwise interior peripheral edges of the frame and being positioned to cooperate with respective first and second endwise groupings of the comb tooth sensors of the proof mass, and first and second lateral groupings of comb teeth along respective first and second opposing interior peripheral lateral edges of the frame and being positioned to cooperate with respective first and second lateral groupings of the comb tooth sensors of the proof mass.