Physical Quantity Sensor

Abstract

To provide a physical quantity sensor capable of suppressing inconveniences caused by resonance of a moving part while maintaining high sensitivity. [Solution] The physical quantity sensor includes a base, a plate-like cantilever having a hinge portion and a movable portion connected to the base via the hinge portion, and a physical quantity detection element fixed to the base and the movable portion. The cantilever also has a first surface and a second surface, which are opposite each other, a first groove formed on the first surface and extending along a second direction that intersects with a first direction in which the hinge portion and the movable portion are aligned in a plan view of the cantilever, and a second groove formed on the second surface, extending along the second direction, and overlapping with the first groove in a plan view of the cantilever. The hinge portion is defined as a region sandwiched between the first groove and the second groove, and the opening of the first groove and the opening of the second groove are offset in the first direction.

Description

[Technical Field]

[0001] The present invention relates to a physical quantity sensor. [Background technology]

[0002] The inertial sensor described in Patent Document 1 has a plate-like structure including a base, a cantilever having a thin constricted portion and a movable portion connected to the base via the constricted portion, an oscillator fixed to the base and the movable portion across the constricted portion, and a mass portion arranged in the movable portion.

[0003] In this type of inertial sensor, when acceleration in the Z-axis direction is applied, the movable part displaces relative to the base part, with the constricted part as the fulcrum. This displacement then applies tensile or compressive stress to the vibrator, and the resonant frequency of the vibrator changes depending on the magnitude of the applied stress. Therefore, the applied acceleration can be detected based on the change in the resonant frequency of the vibrator. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2024-033901 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in an inertial sensor with such a configuration, if external vibrations with a frequency close to the resonant frequency of the cantilever are applied, problems such as output abnormalities, destruction, and an increase in vibration rectification error (VRE) may occur (hereinafter referred to as "failures due to resonance"). Therefore, to prevent such problems from occurring, it is necessary to set the resonant frequency of the cantilever sufficiently high relative to the frequency band being used so that resonance does not occur.

[0006] One way to increase the resonance frequency of the cantilever is to reduce the mass of the moving part. However, reducing the mass of the moving part reduces the sensitivity of the inertial sensor. As such, there is a trade-off between problems caused by cantilever resonance and sensitivity, so it is difficult for the inertial sensor of Patent Document 1 to suppress problems caused by cantilever resonance while maintaining high sensitivity. [Means for solving the problem]

[0007] The physical quantity sensor of the present invention includes a base and a plate-shaped cantilever having a hinge portion and a movable portion connected to the base portion via the hinge portion, wherein the movable portion is displaced relative to the base portion with the hinge portion as a fulcrum; a physical quantity detection element that straddles the hinge portion and is fixed to the base portion and the movable portion, The cantilever has a first surface and a second surface which are opposite surfaces, a first groove formed on the first surface and extending along a second direction intersecting a first direction in which the hinge portion and the movable portion are aligned in a plan view of the cantilever; a second groove formed on the second surface, extending along the second direction, and overlapping with the first groove in a plan view of the cantilever; the hinge portion is defined as a region sandwiched between the first groove and the second groove, The opening of the first groove and the opening of the second groove are offset from each other in the first direction. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a top view showing the inside of a physical quantity sensor according to a preferred embodiment. [Figure 2] FIG. 2 is a cross-sectional view taken along line AA in FIG. [Figure 3] FIG. 1 is a cross-sectional view showing a cantilever of a conventional structure. [Figure 4] 10 is a graph showing the relationship between the effective length of the hinge portion and the resonance frequency of the cantilever. [Figure 5] 10 is a graph showing the relationship between the effective length of the hinge portion and the sensitivity of the physical quantity sensor. [Figure 6] 1A to 1C are diagrams illustrating a manufacturing process of a substrate structure. [Figure 7] 10A to 10C are cross-sectional views for explaining a method for manufacturing a substrate structure. [Figure 8] 10A to 10C are cross-sectional views for explaining a method for manufacturing a substrate structure. [Figure 9] FIG. 10 is a cross-sectional view showing a modified example of the cantilever. [Figure 10] FIG. 10 is a cross-sectional view showing a modified example of the cantilever. DETAILED DESCRIPTION OF THE INVENTION

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A physical quantity sensor according to the present invention will now be described in detail with reference to the embodiments shown in the accompanying drawings.

[0010] FIG. 1 is a top view showing the inside of a physical quantity sensor according to a preferred embodiment. FIG. 2 is a cross-sectional view taken along line AA in FIG. 1. FIG. 3 is a cross-sectional view showing a cantilever of a conventional structure. FIG. 4 is a graph showing the relationship between the effective length of a hinge portion and the resonance frequency of the cantilever. FIG. 5 is a graph showing the relationship between the effective length of a hinge portion and the sensitivity of a physical quantity sensor. FIG. 6 is a diagram showing a manufacturing process of a substrate structure. FIGS. 7 and 8 are cross-sectional views illustrating a manufacturing method of a substrate structure. FIGS. 9 and 10 are cross-sectional views showing modified examples of the cantilever.

[0011] For ease of explanation, the physical quantity sensor will be defined below as having three mutually orthogonal axes: an X-axis, a Y-axis, and a Z-axis. The direction along the X-axis will be referred to as the X-axis direction, the direction along the Y-axis as the Y-axis direction, and the direction along the Z-axis as the Z-axis direction. The arrowed side of each axis will be referred to as the "plus side," and the opposite side as the "minus side." The plus side of the Z-axis direction will be referred to as the "upper side," and the minus side as the "lower side." A planar view from the Z-axis direction, i.e., a planar view of the cantilever 42 described below, will also be referred to simply as a "planar view." In this application, "parallel" refers not only to objects that are parallel to each other, but also to objects that are tilted relative to each other within a range that can be considered equivalent to being parallel in terms of common technical knowledge (e.g., approximately ±5°).

[0012] 1 is an acceleration sensor that detects acceleration in the Z-axis direction. Such physical quantity sensor 1 has a package 2 and a physical quantity sensor element 3 housed in the package 2.

[0013] First, the package 2 will be described. As shown in Fig. 1, the package 2 has a base 21 having a recess 211 that opens on the top surface, and a plate-shaped lid 22 that is joined to the top surface of the base 21 via a joining member so as to close the opening of the recess 211. Inside the package 2, an airtight internal space S is formed by the recess 211, and the physical quantity sensor element 3 is housed in this internal space S.

[0014] For example, the base 21 is made of a ceramic such as alumina, and the lid 22 is made of a metal material such as Kovar. This results in a package 2 with excellent mechanical strength. Furthermore, the difference in linear expansion coefficients between them can be kept small, thereby suppressing the occurrence of thermal stress. However, the materials constituting the base 21 and the lid 22 are not particularly limited. Furthermore, the internal space S is in a reduced pressure state, preferably a state closer to a vacuum. This reduces viscous resistance and improves the vibration characteristics of the physical quantity sensor element 3. However, the atmosphere in the internal space S is not particularly limited.

[0015] As shown in FIG. 1 , the base 21 has three first seats 212a, 212b, and 212c and one second seat 213 that protrude from the bottom surface of the recess 211. The physical quantity sensor element 3 is joined to the first seats 212a, 212b, and 212c via joining members (not shown). Internal terminals 214a and 214b are disposed on the second seat 213. The internal terminals 214a and 214b are electrically connected to the physical quantity sensor element 3 via conductive wires W. Although not shown, two external terminals are disposed on the underside of the base 21. These two external terminals are electrically connected to the internal terminals 214a and 214b via internal wiring (not shown) formed in the base 21. This enables electrical connection to the physical quantity sensor element 3 via the external terminals.

[0016] The above has described the package 2. Next, we will describe the physical quantity sensor element 3. As shown in Fig. 1, the physical quantity sensor element 3 has a substrate structure 4 supported by first pedestals 212a, 212b, and 212c, a physical quantity detection element 5 arranged on the substrate structure 4, and a weight portion 6 arranged on the substrate structure 4.

[0017] The substrate structure 4 is a plate-like monolithic structure formed from a quartz substrate, and is flat along the XY plane perpendicular to the Z axis. The cut angle of the quartz substrate is not particularly limited as long as it functions as a sensor element using the piezoelectric effect, but in this embodiment, it is a Z-cut with the optical axis aligned along the thickness direction. The X-axis, Y-axis, and Z-axis shown in each figure correspond to the crystal axes of the quartz substrate, with the X-axis coinciding with the electrical axis of the quartz substrate, the Y-axis coinciding with the mechanical axis, and the Z-axis coinciding with the optical axis.

[0018] The substrate structure 4 has a base 41, a cantilever 42 connected to the base 41 and displaceable in the Z-axis direction, and an arm 43 supporting the base 41.

[0019] The arm portion 43 has three arms 431, 432, and 433. The arms 431, 432, and 433 are arranged around the base portion 41 and are each connected to the base portion 41. The substrate structure 4 is joined at the tip of each of the arms 431, 432, and 433 to the first pedestals 212a, 212b, and 212c of the base 21 via joining members (not shown). This allows the substrate structure 4 to be supported by the base 21.

[0020] Cantilever 42 is plate-shaped and has hinge portion 421 and movable portion 422 connected to base portion 41 via hinge portion 421. In such cantilever 42, hinge portion 421 is thinner than base portion 41 and movable portion 422 located on either side of it, and movable portion 422 displaces in the Z-axis direction relative to base portion 41, with hinge portion 421 as a fulcrum.

[0021] The physical quantity detection element 5 is a double-ended tuning fork vibration element formed from a quartz substrate. By forming the physical quantity detection element 5 from the same material as the substrate structure 4, the linear expansion coefficients of the physical quantity detection element 5 and the substrate structure 4 can be made equal. This makes it difficult for thermal stress to occur between them. Therefore, thermal stress caused by the difference in linear expansion coefficients between the physical quantity detection element 5 and the substrate structure 4 does not substantially occur, and forces other than the acceleration in the Z-axis direction, which is the detection target, are unlikely to be applied to the physical quantity detection element 5. This results in a physical quantity sensor 1 with high acceleration detection accuracy.

[0022] 1, the physical quantity detection element 5 has two vibrating beams 51 and 52, a first base 53 terminating one ends of the two vibrating beams 51 and 52, and a second base 54 terminating the other ends of the two vibrating beams 51 and 52. In the physical quantity detection element 5, the vibrating beams 51 and 52 are arranged along the X-axis, and the first base 53 is joined to the movable part 422 via a joining member (not shown), and the second base 54 is joined to the base 41 via a joining member (not shown). In other words, the physical quantity detection element 5 is fixed to the base 41 and the movable part 422 across the hinge part 421.

[0023] The physical quantity detection element 5 also has a pair of excitation electrodes (not shown) provided on the vibrating beams 51 and 52. When an AC voltage drive signal is applied between these excitation electrodes, the vibrating beams 51 and 52 flexurally vibrate so as to move away from or towards each other in the Y-axis direction. The pair of excitation electrodes is electrically connected to the internal terminals 214a and 214b via wires W.

[0024] Here, we will first explain a method for detecting acceleration in the Z-axis direction using the physical quantity sensor element 3. When acceleration in the Z-axis direction is applied to the physical quantity sensor 1, the movable part 422 is displaced in the Z-axis direction relative to the base part 41, with the hinge part 421 as the fulcrum. This displacement applies tensile stress or compressive stress to the physical quantity detection element 5, and the resonant frequency of the physical quantity detection element 5 changes depending on the magnitude of the applied stress.

[0025] Specifically, when acceleration is applied to the positive side in the Z axis direction, the movable part 422 is displaced to the negative side in the Z axis direction relative to the base part 41, which applies tensile stress to the physical quantity detection element 5 and increases the resonant frequency of the physical quantity detection element 5. Conversely, when acceleration is applied to the negative side in the Z axis direction, the movable part 422 is displaced to the positive side in the Z axis direction relative to the base part 41, which applies compressive stress to the physical quantity detection element 5 and decreases the resonant frequency of the physical quantity detection element 5. Therefore, the physical quantity sensor 1 can detect acceleration based on a change in the resonant frequency of the physical quantity detection element 5. The resonant frequency of the physical quantity detection element 5 can be detected by detecting the potential of detection electrodes (not shown) provided on the surfaces of the vibrating beams 51 and 52.

[0026] Returning to the explanation of the configuration of the physical quantity sensor element 3, as shown in FIG. 1, the mass 6 is joined to the tip of the upper surface of the movable part 422 via a joining member (not shown). By disposing the mass 6 on the movable part 422, the mass of the movable part 422 increases. Therefore, the movable part 422 becomes more likely to be displaced even with a small acceleration, improving the sensitivity (resolution) of the physical quantity sensor 1. Such a mass 6 is made of a metal material with a relatively high specific gravity, such as copper (Cu), gold (Au), tungsten (W), or various alloys. This allows the mass 6 to be sufficiently heavy while keeping its size small.

[0027] The above is a brief description of the overall configuration of the physical quantity sensor 1. Next, the cantilever 42, which is a feature of the physical quantity sensor 1, will be described in detail.

[0028] FIG. 2 is a cross-sectional view taken along line AA in FIG. 1. As shown in FIG. 2, the cantilever 42 has an upper surface 42a as a first surface and a lower surface 42b as a second surface, which are opposite surfaces. The upper surface 42a and the lower surface 42b are parallel to each other and lie along the XY plane. The cantilever 42 has a first groove 44 formed in the upper surface 42a and a second groove 45 formed in the lower surface 42b. In addition, the first groove 44 and the second groove 45 each extend straight in a plan view along the Y-axis direction, which is a second direction intersecting the X-axis direction, which is a first direction in which the hinge portion 421 and the movable portion 422 are aligned. In addition, the first groove 44 and the second groove 45 overlap in a plan view, and the thin-walled portion sandwiched between the first groove 44 and the second groove 45 is defined as the hinge portion 421.

[0029] Furthermore, the first groove 44 and the second groove 45 are wet-etched grooves formed by wet etching. Wet etching makes it possible to easily form the first groove 44 and the second groove 45. Because the first groove 44 and the second groove 45 are wet-etched surfaces, the crystal planes of the quartz crystal appear on the inner surfaces of the first groove 44 and the second groove 45.

[0030] 2, the first groove 44 has a first bottom surface 441 parallel to the top surface 42a, a first inclined surface 442 located on the positive side of the first bottom surface 441 in the X-axis direction, and a second inclined surface 443 located on the negative side of the first bottom surface 441 in the X-axis direction and having a steeper slope than the first inclined surface 442. The first inclined surface 442 has a gentle slope 442a located on the lower side (the first bottom surface 441 side) and a steep slope 442b located on the upper side (the top surface 42a side) and having a steeper slope than the gentle slope 442a. Similarly, the second inclined surface 443 has a gentle slope 443a located on the lower side (the first bottom surface 441 side) and a steep slope 443b located on the upper side (the top surface 42a side) and having a steeper slope than the gentle slope 443a. Moreover, gentle slope 442a has a gentler slope than gentle slope 443a, and steep slope 442b has a gentler slope than steep slope 443b. Note that "second inclined surface 443 has a steeper slope than first inclined surface 442" means that the length of second inclined surface 443 in the X-axis direction is shorter than the length of first inclined surface 442 in the X-axis direction.

[0031] The second groove 45 appears rotationally symmetrical with the first groove 44 about the Y axis. That is, the second groove 45 has a second bottom surface 451 parallel to the bottom surface 42b, a third inclined surface 452 located on the negative side of the second bottom surface 451 in the X axis direction, and a fourth inclined surface 453 located on the positive side of the second bottom surface 451 in the X axis direction and having a steeper slope than the third inclined surface 452. The third inclined surface 452 has a gentle slope 452a located on the upper side (the second bottom surface 451 side) and a steep slope 452b located on the lower side (the lower surface 42b side) and having a steeper slope than the gentle slope 453a. Similarly, the fourth inclined surface 453 has a gentle slope 453a located on the upper side (the second bottom surface 451 side) and a steep slope 453b located on the lower side (the lower surface 42b side) and having a steeper slope than the gentle slope 453a. Moreover, gentle slope 452a has a gentler slope than gentle slope 453a, and steep slope 452b has a gentler slope than steep slope 453b. Note that "fourth inclined surface 453 has a steeper slope than third inclined surface 452" means that the length of fourth inclined surface 453 in the X-axis direction is shorter than the length of third inclined surface 452 in the X-axis direction.

[0032] However, there is no particular limitation on the number of crystal planes appearing on the inner surface of the first groove 44. Similarly, there is no particular limitation on the number of crystal planes appearing on the inner surface of the second groove 45.

[0033] The first groove 44 and the second groove 45 having the above-described shapes are arranged so that the first bottom surface 441 and the second bottom surface 451 overlap in a plan view. Furthermore, the openings of the first groove 44 and the second groove 45 are arranged so that they are offset from each other in the X-axis direction. Specifically, the opening of the first groove 44 is offset toward the positive side of the X-axis direction with respect to the opening of the second groove 45 so that the steeply inclined second inclined surface 443 and the steeply inclined fourth inclined surface 453 approach each other. By arranging the first groove 44 and the second groove 45 so that they are offset from each other in the X-axis direction in this manner, the following effect can be achieved. Hereinafter, the distance between the end of the first bottom surface 441 on the negative side in the X-axis direction and the end of the second bottom surface 451 on the positive side in the X-axis direction is defined as the effective length L of the hinge portion 421.

[0034] First, we will explain the problem that occurs when the opening of the first groove 44 and the opening of the second groove 45 are not misaligned in the X-axis direction, as shown in FIG. 3 . Hereinafter, this structure will also be referred to as the “conventional structure.” Because the first groove 44 and the second groove 45 are wet-etched grooves and have quartz crystal planes exposed on their inner surfaces, the conventional structure significantly misaligns the first bottom surface 441 and the second bottom surface 451 in the X-axis direction, resulting in a correspondingly longer effective length L. As the effective length L increases, the rigidity of the hinge portion 421, which serves as the fulcrum, decreases, making it difficult to increase the resonant frequency fr of the cantilever 42. Furthermore, as the effective length L increases, the proportion of the hinge portion 421 within the cantilever 42 increases, which correspondingly reduces the mass of the movable portion 422, making it difficult to increase the sensitivity of the physical quantity sensor. Thus, with the conventional structure, it is difficult to increase the resonant frequency fr of the cantilever 42 and the sensitivity of the physical quantity sensor. For example, the sensitivity can be improved by increasing the mass of the weight part 6, but this causes a new problem in that the physical quantity sensor becomes larger in size.

[0035] In contrast to such a conventional structure, in the physical quantity sensor 1 of this embodiment, as shown in FIG. 2 , the opening of the first groove 44 and the opening of the second groove 45 are offset in the X-axis direction, so that the first bottom surface 441 and the second bottom surface 451 overlap, and as a result, the effective length L of the hinge portion 421 is shorter than in the conventional structure. The shorter the effective length L, the greater the rigidity of the hinge portion 421, which serves as a fulcrum, making it easier to increase the resonance frequency fr of the cantilever 42. Furthermore, the shorter the effective length L, the smaller the proportion of the hinge portion 421 in the cantilever 42, and the corresponding increase in the mass of the movable portion 422, making it easier to increase the sensitivity of the physical quantity sensor 1. In this way, in the physical quantity sensor 1 of this embodiment, it is easier to increase the resonance frequency fr of the cantilever 42 and therefore the sensitivity of the physical quantity sensor 1. That is, according to the physical quantity sensor 1 of the present embodiment, the resonance frequency fr of the cantilever 42 can be increased without reducing the volume of the movable part 422, and therefore it is possible to achieve both an increase in the resonance frequency fr of the cantilever 42 and an increase in the sensitivity of the physical quantity sensor 1. Therefore, the physical quantity sensor 1 can effectively suppress defects caused by cantilever resonance while maintaining high sensitivity.

[0036] FIG. 4 shows the relationship between the effective length L and the resonance frequency fr of the cantilever 42. In FIG. 4, L = 500 μm corresponds to the conventional structure. As is clear from the figure, by making the effective length L shorter than that of the conventional structure, the resonance frequency fr of the cantilever 42 can be increased compared to the conventional structure. FIG. 5 shows the relationship between the effective length L and the sensitivity of the physical quantity sensor 1. As in FIG. 4, L = 500 μm in FIG. 5 corresponds to the conventional structure. As is clear from the figure, by making the effective length L shorter than that of the conventional structure, the sensitivity of the physical quantity sensor 1 can be increased compared to the conventional structure.

[0037] In particular, by setting the effective length L to 100 μm or more and 200 μm or less, it is possible to sufficiently increase both the resonance frequency fr of the cantilever 42 and the sensitivity of the physical quantity sensor 1. Therefore, the effective length L is preferably L<500 μm, and more preferably 100 μm≦L≦200 μm. However, the effective length L is not particularly limited.

[0038] The above has described the physical quantity sensor 1. As described above, such physical quantity sensor 1 includes the plate-shaped cantilever 42 that has the base 41, the hinge portion 421, and the movable portion 422 connected to the base 41 via the hinge portion 421, and the movable portion 422 is displaced relative to the base 41 with the hinge portion 421 as a fulcrum, and the physical quantity detection element 5 that straddles the hinge portion 421 and is fixed to the base 41 and the movable portion 422. The cantilever 42 has an upper surface 42a, which is a first surface, and a lower surface 42b, which is a second surface, which are opposite surfaces. The cantilever 42 has a first groove 44 formed on the upper surface 42a and extending along a Y-axis direction, which is a second direction intersecting the X-axis direction, which is a first direction in which the hinge portion 421 and the movable portion 422 are aligned, in a plan view of the cantilever 42. The cantilever 42 also has a second groove 45 formed on the lower surface 42b, which extends along the Y-axis direction and overlaps with the first groove 44 in a plan view of the cantilever 42. The hinge portion 421 is defined as a region sandwiched between the first groove 44 and the second groove 45, and the opening of the first groove 44 and the opening of the second groove 45 are offset in the X-axis direction. This configuration allows the effective length L of the hinge portion 421 to be kept short. This allows the resonant frequency fr of the cantilever 42 to be increased without reducing the volume of the movable portion 422. Therefore, the physical quantity sensor 1 can effectively suppress defects caused by cantilever resonance while maintaining high sensitivity.

[0039] Furthermore, as described above, the first bottom surface 441 of the first groove 44 and the second bottom surface 451 of the second groove 45 overlap in a plan view of the cantilever 42. With this configuration, the effective length L of the hinge portion 421 can be kept short.

[0040] As described above, the base 41 and the cantilever 42 are monolithic structures formed from a quartz substrate, and the first groove 44 and the second groove 45 are wet-etched grooves. With this configuration, crystal planes of the quartz crystal appear in the first groove 44 and the second groove 45. Therefore, when the opening of the first groove 44 and the opening of the second groove 45 are not misaligned in the X-axis direction, that is, in the case of the conventional structure described above, the effective length L of the hinge portion 421 tends to be long. This allows the effect of the physical quantity sensor 1 (the effect produced by misaligning the opening of the first groove 44 and the opening of the second groove 45 in the X-axis direction) to be more pronounced.

[0041] As described above, the first groove 44 has a first bottom surface 441, a first inclined surface 442 located on the positive side of the first bottom surface 441 in the X axis direction (one side in the first direction), and a second inclined surface 443 located on the negative side of the first bottom surface 441 in the X axis direction (the other side in the first direction) and having a steeper slope than the first inclined surface 442. The second groove 45 has a second bottom surface 451, a third inclined surface 452 located on the negative side of the second bottom surface 451 in the X axis direction, and a fourth inclined surface 453 located on the positive side of the second bottom surface 451 in the X axis direction and having a steeper slope than the third inclined surface 452. The opening of the first groove 44 is shifted toward the positive side in the X axis direction with respect to the opening of the second groove 45. With this configuration, the effective length L of the hinge portion 421 can be kept short.

[0042] Next, a description will be given of a manufacturing method of the substrate structure 4. As shown in Fig. 6, the manufacturing method of the substrate structure 4 includes a hinge portion forming step S1 for forming the hinge portion 421 and an outer shape forming step S2 for forming the outer shape of the substrate structure 4.

[0043] [Hinge part forming process S1] First, a Z-cut quartz crystal substrate 40 is prepared as the base material for the substrate structure 4. Next, as shown in FIG. 7, a mask M1 having an opening M11 corresponding to the first groove 44 is formed on the upper surface 40a of the prepared quartz crystal substrate 40, and a mask M2 having an opening M21 corresponding to the second groove 45 is formed on the lower surface 40b of the quartz crystal substrate 40. The opening M11 is shifted in the positive direction of the X axis relative to the opening M21. Next, the quartz crystal substrate 40 is wet-etched using these masks M1 and M2 to form the first groove 44 and the second groove 45 as shown in FIG.

[0044] [Outline forming process S2] Next, the quartz substrate 40 is patterned using various etching techniques such as wet etching and dry etching to form the outer shape of the substrate structure 4. In this manner, the substrate structure 4 is obtained. According to this manufacturing method, the substrate structure 4 can be easily formed.

[0045] Although the physical quantity sensor of the present invention has been described above based on the illustrated embodiment, the present invention is not limited to this, and the configuration of each part can be replaced with any configuration having a similar function. Furthermore, any other configuration may be added to the present invention.

[0046] For example, in the above-described embodiment, the first bottom surface 441 is shifted toward the negative side of the X-axis direction relative to the second bottom surface 451, but this is not limited to this. As shown in FIG. 9, the first bottom surface 441 and the second bottom surface 451 may be coincident, or as shown in FIG. 10, the first bottom surface 441 may be shifted toward the positive side of the X-axis direction relative to the second bottom surface 451. [Explanation of symbols]

[0047] 1...physical quantity sensor, 2...package, 21...base, 211...recess, 212a...first pedestal, 212b...first pedestal, 212c...first pedestal, 213...second pedestal, 214a...internal terminal, 214b...internal terminal, 22...lid, 3...physical quantity sensor element, 4...substrate structure, 40...quartz substrate, 40a...upper surface, 40b...lower surface, 41...base, 42...cantilever, 42a...upper surface, 42b...lower surface, 421...hinge portion, 422...movable portion, 43...arm portion, 431...arm portion, 432...arm portion, 433...arm portion, 44...first groove, 441...first bottom surface, 442...second 1 inclined surface, 442a...gentle slope, 442b...steep slope, 443...second inclined surface, 443a...gentle slope, 443b...steep slope, 45...second groove, 451...second bottom surface, 452...third inclined surface, 452a...gentle slope, 452b...steep slope, 453...fourth inclined surface, 453a...gentle slope, 453b...steep slope, 5...physical quantity detection element, 51...vibrating beam, 52...vibrating beam, 53...first base, 54...second base, 6...weight portion, M1...mask, M11...opening, M2...mask, M21...opening, L...length, S...internal space, S1...hinge portion forming process, S2...outline forming process, W...wire

Claims

1. A base and a plate-shaped cantilever having a hinge portion and a movable portion connected to the base portion via the hinge portion, wherein the movable portion is displaced relative to the base portion with the hinge portion as a fulcrum; a physical quantity detection element that straddles the hinge portion and is fixed to the base portion and the movable portion, The cantilever has a first surface and a second surface which are opposite surfaces, a first groove formed in the first surface and extending along a second direction intersecting a first direction in which the hinge portion and the movable portion are aligned in a plan view of the cantilever; a second groove formed on the second surface, extending along the second direction, and overlapping with the first groove in a plan view of the cantilever; the hinge portion is defined as a region sandwiched between the first groove and the second groove, A physical quantity sensor, characterized in that an opening of the first groove and an opening of the second groove are misaligned in the first direction.

2. The physical quantity sensor according to claim 1 , wherein a first bottom surface of the first groove and a second bottom surface of the second groove overlap with each other in a plan view of the cantilever.

3. the base and the cantilever are monolithic structures formed from a quartz substrate; The physical quantity sensor according to claim 2 , wherein the first groove and the second groove are wet-etched grooves.

4. the first groove has the first bottom surface, a first inclined surface located on one side of the first bottom surface in the first direction, and a second inclined surface located on the other side of the first bottom surface in the first direction and having a steeper inclination than the first inclined surface, the second groove has the second bottom surface, a third inclined surface located on the other side of the second bottom surface in the first direction, and a fourth inclined surface located on the one side of the second bottom surface in the first direction and having a steeper inclination than the third inclined surface, The physical quantity sensor according to claim 3 , wherein the opening of the first groove is shifted toward the one side in the first direction with respect to the opening of the second groove.

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