MEMS ACCELERATION SENSOR
The present invention relates to a MEMS acceleration sensor comprising a substrate and a sensor mass that is disposed parallel to the substrate in an X-Y plane. The sensor mass is rotatable about a rotary axis, and includes a plurality of holes. The weight of the sensor mass is different on the two sides of the rotary axis. The sensor further includes sensor elements for detecting a rotary motion of the sensor mass about the rotary axis. To change the weight of the sensor mass on one side of the rotary axis relative to the other side, material of the sensor mass is partially removed in some of the holes for reducing the weight of the sensor mass, and/or material of the sensor mass is added in the Z-direction, in particular in the extension of the holes, for increasing the weight of the sensor mass.
1 . An MEMS acceleration sensor, comprising:
a substrate;
a sensor mass that is disposed parallel to the substrate in an X-Y plane, the sensor mass being attached to the substrate that is rotatable about a rotary axis, the sensor mass comprising a plurality of holes, the weight of the sensor mass being different on the two sides of the rotary axis, the sensor mass including sensor elements for detecting a rotary motion of the sensor mass about the rotary axis; and
wherein in order to change the weight of the sensor mass on one side of the rotary axis relative to the other side of the rotary axis, material of the sensor mass is changed by at least one of the two methods including (a) partially removing material of the sensor mass in the region of some of the plurality of holes for reducing the weight of the sensor mass and (b) adding material of the sensor mass in the Z-direction in the extension of some of the plurality of holes for increasing the weight of the sensor mass.
2 . The MEMS acceleration sensor according to claim 1 , wherein the rotary axis is disposed symmetrically with respect to a projection surface of the sensor mass.
3 . The MEMS acceleration sensor according to claim 1 , wherein the plurality of holes are through holes.
4 . The MEMS acceleration sensor according to claim 1 , wherein some of the plurality of holes are stepped.
5 . The MEMS acceleration sensor according to claim 1 , wherein some of the plurality of holes are conical.
6 . The MEMS acceleration sensor according to claim 1 , wherein in method (a), the material of the sensor mass is at least partially removed on one side in order to produce a thinner wall of the sensor mass.
7 . The MEMS acceleration sensor according to claim 1 , wherein in method (b), the material is at least partially added to the sensor mass in order to produce a thicker wall of the sensor mass.
8 . The MEMS acceleration sensor according to claim 1 , wherein in method (b) and (a), the material is added to and removed from the side of the sensor mass facing away from the sensor elements, respectively.
9 . The MEMS acceleration sensor according to claim 1 , wherein in method (b) and (a), the material is added to and removed from outside the region of the sensor mass in which the sensor elements are disposed, respectively.
10 . The MEMS acceleration sensor according to claim 1 , wherein the sensor mass is rotatably mounted for sensing at least one rotation between rotations within and out of the X-Y plane.
11 . The MEMS acceleration sensor according to claim 1 , wherein the MEMS acceleration sensor comprises a plurality of sensor masses for detecting accelerations in a plurality of directions.