Method and structure of an inertial sensor using tilt conversion
A method and structure for fabricating an inertial sensing device using tilt conversion to sense a force in the out-of-plane direction. The method can include forming anchor structure(s) coupled to portions of a surface region of a substrate member. Also, the method can include forming flexible anchor members coupled to portions of the anchor structures and frame structures, which can be formed overlying the substrate. The method can also include forming flexible frame members coupled to portions of the frame structures and movable structures, which can also be formed overlying the substrate. Forming the movable structures can include forming peripheral and central movable structures, which can be coupled to flexible structure members. Peripheral movable structures having flexible tilting members can convert a pure tilting out-of-plane motion to a pure translational out-of-plane motion. The forming of these elements can include performing an etching process on a single silicon material.
1. An inertial sensing device disposed upon a substrate member having a surface region, the device comprising:
eight anchor structures, the anchor structures being coupled to at least one portion of the surface region;
two frame structures, the frame structures spatially disposed overlying at least one portion of the surface region, each of the frame structures being coupled to four of the anchor structure(s);
four peripheral movable structures, the peripheral movable structures spatially disposed overlying at least one portion of the surface region, each of the peripheral movable structures having two flexible tilting members;
two central movable structures, the central movable structures having at least one portion coupled to each of the flexible tilting members of two peripheral movable structures;
eight first flexible members, each of the first flexible members being coupled to one of the anchor structures and at least one portion of the frame structures; and
eight second flexible members, two of the second flexible members being coupled to at least one portion of the frame structure(s) and each of the peripheral movable structures.
2. The device of claim 1 further comprising an integrated circuit layer, the integrated circuit layer being formed overlying at least one portion of the surface region.
3. The device of claim 1 further comprising two flexible coupling members, the flexible coupling members being coupled to at least one portion of each of the frame structures.
4. The device of claim 3 wherein the flexible coupling member(s), the flexible tilting member(s), and the first and second flexible member(s) comprise torsion spring(s) or bending spring(s).
5. The device of claim 1 further comprising at least one comb structure, the comb structure(s) being coupled to at least one portion of the frame structure(s).
6. The device of claim 5 wherein the comb structure(s) comprise anti-phase driving comb structure(s).
7. The device of claim 1 wherein the peripheral movable structure(s) and the flexible tilting member(s) are configured to convert a pure tilting out-of-plane motion to a pure translational out-of-plane motion for the purpose of sensing an out-of-plane motion.
8. The device of claim 1 wherein the central movable structure(s) comprise at least one capacitor element.
9. The device of claim 1 wherein the peripheral movable structure(s) and the flexible tilting member(s) are configured to detect weak displacements due to a Coriolis force.