The present invention provides a high-accuracy low-noise MEMS accelerometer by using a larger, single proof mass to measure acceleration along two orthogonal axes. A novel arrangement of electrodes passively prevents cross axis error in the acceleration measurements. Novel arrangements of springs and a novel proof mass layout provide further noise reduction.

A physical quantity sensor includes a base unit as a support substrate, provided with a cavity that is open on one side, a movable unit which is formed on an open side of the cavity and is capable of displacing in a first direction, and spring units that are formed on the open side of the cavity and are connected to the movable unit. A length of the spring units in a second direction that is a direction, which intersects the first direction and in which the base unit overlaps the movable unit, is shorter than a length of the movable unit in the second direction and is longer than a length of the spring units in the first direction.

A micromechanical z-inertial sensor includes a substrate; a movable seismic mass in a micromechanical functional layer; a torsion spring connected to the movable seismic mass and about which the seismic mass able to rotate; an electrode layer below the seismic mass and that, in an outer region is connectible to a potential of the substrate and is connected to the seismic mass via an insulating layer; and electrodes at a distance above and below an inner region of the electrode surface.

A MEMS accelerometer incorporating a metrology element to directly measure minute changes in measurement baseline. In particular, the MEMS accelerometer incorporates a metrology bar (MB). Embodiments also relate to stress isolation into the sensor design to isolate the sensitive areas of the chip (i.e., the metrology baseline and the proof mass mounting points) from outside stress.

A physical quantity sensor includes a base unit as a support substrate, provided with a cavity that is open on one side, a movable unit which is formed on an open side of the cavity and is capable of displacing in a first direction, and spring units that are formed on the open side of the cavity and are connected to the movable unit. A length of the spring units in a second direction that is a direction, which intersects the first direction and in which the base unit overlaps the movable unit, is shorter than a length of the movable unit in the second direction and is longer than a length of the spring units in the first direction.

An example Micro Electro-Mechanical Systems (MEMS) accelerometer device includes a proof mass comprising at least one of one or more isolated conductive coil traces or one or more pick-off combs within the proof mass, the one or more pick-off combs comprising a plurality of pick-off comb tines; a pole-piece layer coupled to the proof mass; and a return-path layer coupled to the proof mass, wherein the at least one of the one or more isolated conductive coil traces or the one or more pick-off combs are formed by selective laser etching.

An example proof mass includes a substrate; one or more etched apertures in the substrate; and one or more integrated coils, wherein the one or more etched apertures are formed by selective laser etching, wherein the one or more integrated coils are formed by laser ablation.