Micromechanical structures and micromechanical sensors

Abstract

The invention relates to a micromechanical structure having a substrate and a vibrating mass movable relative to the substrate and first and second detection means. A first direction and a second direction substantially perpendicular thereto define a main extension plane of the substrate. The first detection means are for detecting a translational deflection of the vibrating mass. The second detection means are for detecting a rotational deflection of the vibrating mass. The vibrating mass is connected to the substrate by an anchor and four torsional spring sections. The first detection means have an electrode structure comprising a first electrode fixed to the vibrating mass and a second electrode fixed to the substrate. The first electrode and the second electrode have a substantially two-dimensional extension in the second direction and in a third direction perpendicular to the main extension plane. The anchor has a first section and a second section with a gap arranged therebetween. A connection connects the two first electrodes, the connection guiding through the gap. The invention further relates to a micromechanical sensor comprising such a micromechanical structure and an electrical circuit for reading the detection means.

Description

Technical Field

[0001] This invention relates to a micromechanical structure and a micromechanical sensor. Background Technology

[0002] Micromechanical structures and micromechanical sensors are known from existing technologies. For example, a micromechanical sensor is known from document DE 10 2008 001 442A1, in which a first detection mechanism can determine the translational deflection of a vibrating mass along a first direction, and a second detection mechanism can determine the rotational deflection about a rotation axis parallel to a second direction of the vibrating mass. From this, the accelerations of the micromechanical structure along the first and third directions can be calculated, where these three directions are orthogonal. The detection mechanism includes electrodes, which are disposed either on the vibrating mass or on a substrate. Summary of the Invention

[0003] The objective of this invention is to provide an improved micromechanical structure that reduces the probability of electrode contact in a detection mechanism. Another objective of this invention is to provide a micromechanical sensor having such a micromechanical structure.

[0004] The aforementioned task is solved by the content of this invention. Advantageous improvements are given in the specification and drawings.

[0005] The micromechanical structure has a substrate and a vibrating mass movable relative to the substrate, as well as a first detection mechanism and a second detection mechanism. A first direction and a second direction substantially perpendicular to the first direction define a main extension plane of the substrate. The first detection mechanism is configured to detect translational deflection of the vibrating mass along the first direction. The second detection mechanism is configured to detect rotational deflection of the vibrating mass about a rotation axis, wherein the rotation axis is arranged along the second direction. The vibrating mass is connected to the substrate by an anchor and four torsion spring segments arranged along the second direction. The first detection mechanism has an electrode structure comprising a first electrode fixed to the vibrating mass and a second electrode fixed to the substrate. The first and second electrodes have substantially two-dimensional extensions along the second direction and a third direction, wherein the third direction is perpendicular to the main extension plane. The anchor has a first segment and a second segment, wherein a gap is provided between the first segment and the second segment. A connector connects the two first electrodes, wherein the connector is guided through the gap.

[0006] The connector improves the mechanical stability of the first electrode. This results in an extended lifespan for the micromechanical structure because the sensitivity of the first detection mechanism is persistently reduced in the event of contact between the first and second electrodes due to mechanical instability. In other words, improved mechanical stability leads to improved lifespan.

[0007] The improved mechanical stability of the first electrode is beneficial for mechanical robustness, for example, under mechanical overload and / or during mechanically caused collapses (Kollaps). Furthermore, the probability of electrically caused collapses of the first and second electrodes is reduced via the connector. Therefore, the probability of the electrodes contacting each other by electro-attraction is reduced. Comparable mechanical stability can only be achieved with a very thick first electrode without the connector. Thus, mass and area can be saved with the connector while maintaining the same mechanical robustness.

[0008] In one embodiment of the micromechanical structure, a plurality of first electrodes are disposed on a first side of the anchor, and a plurality of first electrodes are disposed on a second side of the anchor opposite to the first side. A first lateral structure connects the first electrodes on the first side to a connector. A second lateral structure connects the first electrodes on the second side to the connector. This further improves mechanical stability.

[0009] In one embodiment of the micromechanical structure, the connector has at least one first protrusion. The spacing between the connector and the substrate in the region of the first protrusion is reduced compared to the spacing between the connector and the substrate outside the first protrusion. This reduces the mechanical impact of the connector on the first protrusion on the substrate and thus similarly improves the mechanical stability of the micromechanical structure. This results in an extended lifespan for the micromechanical structure.

[0010] In one embodiment of the micromechanical structure, the connector has at least one second protrusion, in which the spacing between the connector and the anchor is reduced compared to the spacing between the connector and the anchor outside the second protrusion. This reduces the mechanical impact of the connector structure on the substrate against the first protrusion and thus similarly improves the mechanical stability of the micromechanical structure.

[0011] The two embodiments described above can be combined. In this case, these raised portions can be referred to as the first and second raised portions as described above. If only the first raised portion or only the second raised portion is provided, then these raised portions can also be generally referred to as raised portions.

[0012] In one embodiment of the micromechanical structure, the vibrating mass has a frame, with a torsion spring segment adjacent to the frame and the anchor. A first electrode is adjacent to the frame. This allows for further improvement in the mechanical stability of the micromechanical structure.

[0013] In one embodiment of the micromechanical structure, two outer regions and two inner regions are formed by torsion spring segments, anchors, and a frame. The outer regions are located between the frame and each of the two torsion spring segments. The inner regions are each located between the two torsion spring segments, the frame, and the anchors. A connector links the first electrodes, each located in one of the inner regions, to each other.

[0014] In one embodiment of the micromechanical structure, the frame has an asymmetrical mass distribution along a first direction with respect to the anchor and torsion spring sections. This enables the conversion of the acceleration of the vibrating mass along a third direction into rotational deflection about the axis of rotation.

[0015] In one embodiment of the micromechanical structure, the second detection mechanism includes a third electrode disposed on a frame and a fourth electrode disposed on a substrate. This enables capacitive determination of the deflection of the vibrating mass about a rotation axis.

[0016] The micromechanical sensor includes the micromechanical structure and an electrical circuit for reading the first and second detection mechanisms.

[0017] In one embodiment of the micromechanical sensor, the electrical circuitry is configured to determine the first capacitance of a first capacitor formed by at least one first electrode and at least one second electrode, and the second capacitance of a second capacitor formed by at least one third electrode and at least one fourth electrode. Attached Figure Description

[0018] Embodiments of the invention are illustrated with the aid of the following figures. In the schematic diagram:

[0019] Figure 1 : Shows a top view of the micromechanical structure;

[0020] Figure 2 : Show Figure 1 The cross-section of the micromechanical structure;

[0021] Figure 3 : Show Figure 1 Another cross-section of the micromechanical structure;

[0022] Figure 4 : Shows a top view of another micromechanical structure;

[0023] Figure 5 : Show Figure 4 The cross-section of the micromechanical structure;

[0024] Figure 6 : Shows a top view of another micromechanical structure;

[0025] Figure 7 : Show Figure 6 The cross-section of the micromechanical structure;

[0026] Figure 8 : Showing a top view of another micromechanical structure; and

[0027] Figure 9 : This shows a micromechanical sensor. Detailed Implementation

[0028] Figure 1 A top view of the micromechanical structure 1, including the substrate 2 and the vibrating mass 3, is shown. Figure 2 Show Figure 1 The cross section of the micromechanical structure 1 at the section line denoted by A. Figure 3 Show Figure 1 The cross-section of the micromechanical structure 1 at the section line denoted by B. In the following text, by means of... Figures 1 to 3 Describe micromechanical structures, where it is possible that individual components are not visible in all figures.

[0029] The micromechanical structure 1 has a first detection mechanism 4 and a second detection mechanism 5. A first direction 11 and a second direction 12 define the main extension plane of the substrate, wherein the first direction 11 and the second direction 12 are substantially perpendicular to each other, and in particular, perpendicular to each other. The first detection mechanism 4 is configured to detect the translational deflection of the vibrating mass 3 along the first direction 11. The second detection mechanism 5 is configured to detect the rotational deflection of the vibrating mass 3 about a rotation axis, wherein the rotation axis is substantially parallel to the second direction 12, and in particular, parallel to the second direction 12. The vibrating mass 3 is connected to the substrate 2 by an anchor 6 and four torsion spring segments 7. Here, the anchor 6 is connected to the substrate 2 and the torsion spring segments 7, which are connected to the anchor 6 and the vibrating mass 3.

[0030] The first detection mechanism 4 includes an electrode structure comprising a first electrode 41 and a second electrode 42, wherein the first electrode 41 is fixed to the vibrating mass 3 and the second electrode 42 is fixed to the substrate. The first electrode 41 and the second electrode 42 have substantially two-dimensional extensions along a second direction 12 and a third direction 13, wherein the third direction 13 is substantially perpendicular to the main extension plane. In other words, the extension of the first electrode 41 or the second electrode 42 along the first direction 11 is less than the extension along the second direction 12 or the third direction 13.

[0031] Anchor 6 has a first section 61 and a second section 62. A gap 63 is provided between the first section 61 and the second section 62. Connector 8 connects the two first electrodes 41 and guides them through this gap. Connector 8 enables improved mechanical stability of the first electrodes connected by connector 8.

[0032] If the vibration mass 3 deflects from its rest position along the first direction 11 due to the acceleration acting on it along the first direction 11, then the first electrode 41 connected to the vibration mass 3 moves relative to the second electrode 42 connected to the substrate 2. This movement can be detected as a change in the capacitance of the first capacitor formed by the first electrode 41 and the second electrode 42. Here, the degree of this movement is related to the first elastic constant of the torsion spring segment 7, which gives the degree of deflection of the torsion spring segment 7 along the first direction 11 with respect to the force acting on it.

[0033] Figures 1 to 3 Another feature of the micromechanical structure 1 described herein is optional and constitutes a preferred embodiment.

[0034] Two first electrodes 41 are provided on the first side 64 of the anchor 6, and two first electrodes 41 are also provided on the second side 65 of the anchor 6 opposite to the first side 64. The first electrodes 41 on the first side 64 are connected to the connector 8 by means of a first transverse structure 81. The first electrodes 41 on the second side 65 are connected to the connector 8 by means of a second transverse structure 82. It can be configured that each of the first side 64 and the second side 65 has electrodes 41 corresponding to the first electrode 41. Figures 1 to 3 Different numbers of first electrodes 41.

[0035] The vibrating mass 3 has a frame 31. A torsion spring section 7 is adjacent to the frame 31 and the anchor 6. A first electrode 41 is adjacent to the frame.

[0036] Two outer regions 34 and two inner regions 35 are formed by a frame 31, an anchor 6, and a torsion spring section 7. The outer regions 34 are located between the frame 31 and each of the two torsion spring sections 7. The inner regions 35 are each located between the frame 31, the two torsion spring sections 7, and the anchor 6. A connector 8 connects the first electrodes 41 located in one of the inner regions 35 to each other. Specifically, the connector 8 connects all the first electrodes 41 in one of the inner regions 35 to all the first electrodes 41 in the other inner regions 35.

[0037] The frame 31 has a first mass 32 and a second mass 33, each externally positioned on the vibrating mass 3 about a first direction 11. Because the second mass 33 is greater than the first mass 32, the acceleration of the micromechanical structure 3 along the third direction 13 causes the vibrating mass 3 to rotate about an axis of rotation parallel to the second direction 12. The asymmetrical mass distribution provided by the first mass 32 and the second mass 33 is necessary for this effect.

[0038] The second detection mechanism 5 has a third electrode 53 disposed on the frame 31 and a fourth electrode 54 disposed on the substrate 2. If the vibrating mass 3 rotates from a rest position about a rotation axis parallel to the second direction 12 based on the acceleration acting on the vibrating mass 3 along the third direction 13, then the third electrode 53 connected to the vibrating mass 3 or the frame 31 moves relative to the fourth electrode 54 connected to the substrate 2. This movement can be detected as a change in capacitance of a first capacitor formed by the third electrode 53 and the fourth electrode 54. Here, the degree of this movement is related to the second elastic constant of the torsion spring segment 7, which describes a measure of the torsional stiffness of the torsion spring segment 7. Instead of the second detection mechanism 5 shown, other second detection mechanisms 5 may be provided, which can be used to detect rotational deflection about a rotation axis parallel to the second axis 12.

[0039] Each of the first electrodes 41 is configured with two second electrodes 42, so that the two second electrodes 42 and one first electrode 41 are always part of the detection mechanism 4. In each detection mechanism, when deflected along the first direction 11, the plate spacing of the first capacitor formed by one of the first electrodes 41 and the second electrodes 42 decreases, while the plate spacing of the other capacitor formed by the other of the first electrodes 41 and the second electrodes 42 increases.

[0040] Figure 4 A top view of a portion of another micromechanical structure 1 is shown, which corresponds to... Figures 1 to 3 The micromechanical structure 1, unless otherwise described below. Figure 4 The inner region 35 is shown in particular. In the outer region 34, the micromechanical structure 1 can be particularly related to... Figures 1 to 3 The micromechanical structure 1 is the same. In the inner region 35, only one first electrode 41 and two second electrodes 42 are provided on the first side 64 and the second side 65 respectively. The connector 8 connects the first electrode 41. Since only one first electrode 41 is provided in the inner region 35, there are no transverse structures 81 and 82.

[0041] In the regions where the segments 61 and 62 of the anchor 6 connect with the torsion spring segments 7, each of the anchor 6 has a tapered portion 66. It can be configured such that the anchor 6 is not guided along a third direction 13 to the substrate 2 in the region of the tapered portion 66, thereby forming a continuous torsion spring 71 for the two torsion spring segments 7 adjacent to the first segment 61 and the two torsion spring segments 7 adjacent to the second segment 62.

[0042] Figure 4 The two design schemes of the micromechanical structure 1 can also be set independently of each other. Figures 1 to 3 In micromechanical structures.

[0043] Figure 5 Shown in Figure 4 At the cross-section line indicated by C of the middle connector 8 Figure 4 The cross-section of the micromechanical structure 1 is shown. The connector 8 has a first protrusion 83. The first protrusion is disposed between the connector 8 and the substrate 2. The first protrusion 83 reduces the gap between the substrate 2 and the connector 8 compared to the area outside the first protrusion 83. The first protrusion 83 is used to: prevent the vibrating mass 3 from colliding with the substrate 2 or at least make such collision difficult if the vibrating mass 3 is to move toward the substrate 2 based on a force acting on the micromechanical structure 1 in a third direction 13. In particular, it is intended to prevent the connector 8 from colliding with the substrate 2 or at least make such colliding difficult.

[0044] Compared to Figure 5 The illustration may also include multiple first raised portions 83. (And...) Figure 5 The same design scheme can also be set in the first raised part 83. Figures 1 to 3 In the micromechanical structure 1. In this case, it is also possible to set, add, or replace in Figure 5 The first raised portion 83 shown in the figure is provided on the first transverse structure 81 or the second transverse structure 82. One or more first raised portions 83 are provided on the first transverse structure 81 or the second transverse structure 82.

[0045] Compared to Figure 5 As shown in the diagram, the frame 31 can also be designed such that the frame 31 has the same extension as the first electrode 41 along the third direction 13.

[0046] Figure 6 A top view of a portion of another micromechanical structure 1 is shown, which corresponds to... Figures 1 to 3 The micromechanical structure 1, unless otherwise described below. Figure 7 Shown in Figure 6 At the section line represented by D in the middle Figure 6 The cross-section of the micromechanical structure 1. Figure 6 The inner region 35 is shown in particular. In the outer region 34, the micromechanical structure 1 can be particularly connected with... Figures 1 to 3The micromechanical structure 1 is identical. The connector 8 has two second protrusions 84. The second protrusions 84 reduce the gap between the connector 8 and the anchor 6 compared to the area outside the second protrusions 84. The second protrusions 84 are used to: prevent the vibrating mass 3 from colliding with the substrate 2 or at least make such collision difficult if the vibrating mass 3 is to move based on the force acting on the micromechanical structure 1 along the first direction 11. In particular, it should prevent the connector 8 from colliding with the anchor 6 or at least make such colliding difficult. More than two second protrusions 84 or only one second protrusion 84 may be provided. Alternatively, the connector 8 and the first electrode 41 may also have a joint Figure 4 and 5 The characteristics described.

[0047] Compared to Figure 7 The diagram shows that the torsion spring section 7 can also be designed such that the torsion spring section 7 has the same extension as the first electrode 41 along the third direction 13.

[0048] exist Figure 6 and 7 The second raised portion 84 shown can replace or be added to the joint. Figure 5 The first raised portion 83 is described. If only the first raised portion 83 or only the second raised portion 84 is provided, these raised portions can also be generally referred to as raised portion 83 or raised portion 84.

[0049] Figure 8 A top view of another micromechanical structure 1 is shown, which corresponds to... Figures 1 to 3 The micromechanical structure 1, unless otherwise described below, has additional connectors 85 between the first electrodes 41 in the outer region 34, each connecting the two first electrodes 41 to each other. This further improves the mechanical stability of the micromechanical structure 1. Here, the design of the connectors 8 can be combined as follows: Figures 1 to 7 As described. The additional connector 85 can be combined as follows. Figure 5 It has a first raised portion 83 as described.

[0050] Here, the micromechanical structure 1 can be made of silicon. In particular, electrodes 41, 42, 53, and 54 can also be made of silicon, especially doped silicon. To fabricate the micromechanical structure, silicon and silicon oxide can be arranged in layers such that the micromechanical structure 1 made of silicon is retained after the silicon oxide is removed, for example, by means of an etching process.

[0051] Figure 9 Showing has in Figures 1 to 8The micromechanical sensor 9 has a micromechanical structure as described herein. The micromechanical sensor 9 also has an electrical circuit 91, which can be used to read the detection mechanisms 4 and 5. Specifically, the electrical circuit 91 can be configured to analyze and process changes in the capacitance of a first capacitor formed by the first electrode 41 and the second electrode 42, and to analyze and process changes in the capacitance of a second capacitor formed by the third electrode 53 and the fourth electrode 54.

[0052] Although the invention has been described in detail through various preferred embodiments, the invention is not limited to the disclosed examples, and other variations thereof can be derived by those skilled in the art without departing from the scope of protection of the invention.

Claims

1. A micromechanical structure (1) having a substrate (2) and a vibrating mass (3) movable relative to the substrate (2), and further having a first detection mechanism (4) and a second detection mechanism (5), wherein a first direction (11) and a second direction (12) substantially perpendicular to the first direction (11) define a principal extension plane of the substrate (2), wherein the first detection mechanism (4) is configured to detect translational deflection of the vibrating mass (3) along the first direction (11), wherein the second detection mechanism (5) is configured to detect rotational deflection of the vibrating mass (3) about a rotation axis, wherein the rotation axis is arranged along the second direction (12), wherein the vibrating mass (3) is connected to the substrate (2) by an anchor (6) and four torsion spring segments (7) arranged along the second direction. The substrate (2) is connected, wherein the first detection mechanism (4) has an electrode structure comprising a first electrode (41) fixed on the vibrating mass (3) and a second electrode (42) fixed on the substrate (2), wherein the first electrode (41) and the second electrode (42) have substantially two-dimensional extensions along a second direction (12) and along a third direction (13), wherein the third direction (13) is perpendicular to the main extension plane, wherein the anchor (6) has a first segment (61) and a second segment (62), wherein a gap (63) is provided between the first segment (61) and the second segment (62), wherein a connector (8) connects the two first electrodes (41), wherein the connector (8) is guided through the gap (63).

2. The micromechanical structure (1) according to claim 1, wherein, A plurality of first electrodes (41) are disposed on a first side (64) of the anchor (6), wherein the plurality of first electrodes (41) are disposed on a second side (65) of the anchor (6) opposite to the first side (64), wherein a first transverse structure (81) connects the first electrodes (41) on the first side (64) to the connector (8), and a second transverse structure (82) connects the first electrodes (41) on the second side (65) to the connector (8).

3. The micromechanical structure (1) according to claim 1 or 2, wherein, The connector (8) has at least one first protrusion (83), and the spacing between the connector (8) and the substrate (2) in the region of the first protrusion (83) is reduced compared to the spacing between the connector (8) and the substrate (2) outside the first protrusion (83).

4. The micromechanical structure (1) according to claim 1 or 2, wherein, The connector (8) has at least one second protrusion (84), and the interval between the connector (8) and the anchor (6) in the region of the second protrusion (84) is reduced compared to the interval between the connector (8) and the anchor (6) outside the second protrusion (84).

5. The micromechanical structure (1) according to claim 1 or 2, wherein, The vibrating mass (3) has a frame (31), wherein the torsion spring segment (7) is adjacent to the frame (31) and the anchor (6), wherein the first electrode (41) is adjacent to the frame (31).

6. The micromechanical structure (1) according to claim 5, wherein, Two outer regions (34) and two inner regions (35) are formed by the torsion spring section (7), the anchor (6) and the frame (31), wherein the outer region (34) is disposed between the frame (31) and the two torsion spring sections (7) respectively, wherein the inner regions (35) are disposed between the two torsion spring sections (7), the frame (31) and the anchor (6) respectively, wherein the connector (8) connects the first electrode (41) disposed in one of the inner regions (35) to each other.

7. The micromechanical structure (1) according to claim 5, wherein, The frame (31) has an asymmetrical mass distribution (32, 33) along the first direction (11) with respect to the anchor (6) and the torsion spring section (7).

8. The micromechanical structure (1) according to claim 5, wherein, The second detection mechanism (5) includes a third electrode (53) disposed on the frame (31) and a fourth electrode (54) disposed on the substrate (2).

9. A micromechanical sensor (9) comprising a micromechanical structure (1) according to any one of claims 1 to 8 and an electrical circuit (91) for reading a first detection mechanism (4) and a second detection mechanism (5).

10. The micromechanical sensor (9) according to claim 9, wherein, The electrical circuit (91) is configured to determine the first capacitance of a first capacitor formed by at least one first electrode (41) and at least one second electrode (42) and the second capacitance of a second capacitor formed by at least one third electrode (53) and at least one fourth electrode (54).

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