Micromechanical tilt sensor
First Claim
1. Sensor for tilt measurement, having a sensor element made from a monocrystalline silicon wafer (10), a movable silicon mass (16) etched out of said wafer (10), and means for evaluation of the displacement of said silicon mass,characterized in thatsaid silicon mass (16) is defined by a surrounding etch groove (13) which completely penetrates silicon wafer (10), said mass (16) being connected to said silicon wafer (10) by two torsion bars aligned along a single axis,said silicon mass (16) is movable by a rotation about the bar axis by twisting of said torsion bars (14, 15),said sensor element is connected to at least one of an upper cover (11) and a lower cover (12),on at least one of said covers (11, 12) at least two electrodes (19,20) are provided in the area of the silicon mass (16), andsaid silicon mass (16) and two electrodes (19,20) form capacitances whose difference in values is used for evaluation of the movement of the silicon mass.
1 Assignment
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Accused Products
Abstract
A sensor for measurement of tilt or inclination angle features a sensor element made from a monocrystalline silicon wafer, from which is etched at least one movable silicon mass. The silicon mass is freed from the surrounding wafer by an etch groove which completely penetrates the silicon wafer, and is connected to the silicon wafer by two bars lying in a common axis, so that, upon flexing or torsioning of the bars, the silicon mass is movable or rotatable about the axis of the bars. The sensor element is connected with an upper and/or a lower cover. On at least one of the covers, adjacent the silicon mass, at least two electrodes are placed. The silicon mass and the two electrodes form a pair of capacitances, and the movement or excursion of the silicon mass is detected by evaluation of the difference between the capacitances.
54 Citations
17 Claims
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1. Sensor for tilt measurement, having a sensor element made from a monocrystalline silicon wafer (10), a movable silicon mass (16) etched out of said wafer (10), and means for evaluation of the displacement of said silicon mass,
characterized in that said silicon mass (16) is defined by a surrounding etch groove (13) which completely penetrates silicon wafer (10), said mass (16) being connected to said silicon wafer (10) by two torsion bars aligned along a single axis, said silicon mass (16) is movable by a rotation about the bar axis by twisting of said torsion bars (14, 15), said sensor element is connected to at least one of an upper cover (11) and a lower cover (12), on at least one of said covers (11, 12) at least two electrodes (19,20) are provided in the area of the silicon mass (16), and said silicon mass (16) and two electrodes (19,20) form capacitances whose difference in values is used for evaluation of the movement of the silicon mass.
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14. Method of making a sensor element for a sensor,
comprising the steps of performing anisotropic wet chemical etching from the back side of a silicon wafer (10) to free and define a silicon mass (16) from a substrate layer (9), using the epitaxial layer (8) as an etch-stop for the back side etching, and performing isotropic or anisotropic etching from the front side of the silicon wafer (10) to free and define the silicon mass (16) and the bars (14, 15).
Specification