Capacitive sensor

Abstract

A capacitive sensor (1) comprises: a top layer (70) having a boss part (72) that receives a force applied in at least one of a first direction and a second direction intersecting the first direction; a diaphragm layer (50) that is laminated on the top layer (70) in a third direction intersecting the first direction and the second direction and that is deformed on the basis of the force applied to the boss part (72); and an electrode layer (30) that is laminated on the diaphragm layer (50) in the third direction and that has an electrode (33) for forming capacitance that changes on the basis of the force applied to the boss part (72). A first hole (SL1) that opens in the third direction is formed in a region of the diaphragm layer (50) overlapping the boss part (72).

Description

Capacitive Sensor

[0001] The present invention relates to a capacitance type sensor.

[0002] Micro Electro Mechanical Systems (MEMS) devices manufactured using MEMS technology are becoming widespread, and are used, for example, in capacitance sensors that detect inertia, pressure, and the like based on changes in capacitance.

[0003] For example, Patent Document 1 discloses a mechanical quantity MEMS sensor that includes a first silicon layer and a second silicon layer bonded to the first silicon layer via a silicon oxide film, the first silicon layer having a protrusion to which a force is applied and a diaphragm that elastically deforms in response to the application of force to the protrusion, and that detects the mechanical quantity applied to the protrusion based on a change in capacitance formed by the second silicon layer.

[0004] Patent No. 5714648

[0005] In the mechanical quantity MEMS sensor described in Patent Document 1, it is necessary to improve the flexibility of the diaphragm in order to improve the detection sensitivity. However, when an attempt is made to improve the flexibility of the diaphragm by thinning the diaphragm, variations in thickness processing may result in insufficient improvement in the detection sensitivity.

[0006] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a capacitance type sensor that can improve detection sensitivity.

[0007] A capacitance-type sensor according to one aspect of the present invention comprises a top layer having a boss portion that receives a force acting in at least one of a first direction and a second direction intersecting the first direction; a diaphragm layer that is stacked on the top layer in a third direction intersecting the first and second directions and that deforms based on the force acting on the boss portion; and an electrode layer that is stacked on the diaphragm layer in the third direction and has an electrode for forming a capacitance that changes based on the force acting on the boss portion, and a first hole portion that opens in the third direction is formed in the area of ​​the diaphragm layer that overlaps with the boss portion.

[0008] According to the present invention, it is possible to provide a capacitance type sensor that can improve detection sensitivity.

[0009] FIG. 1 is a cross-sectional view of a capacitance-type sensor according to a first embodiment; FIG. 2 is a plan view of a top layer according to a first embodiment; FIG. 3 is a plan view of a diaphragm layer according to a first embodiment; FIG. 4 is a plan view of an electrode layer according to a first embodiment; FIG. 5 is a plan view of an electrode layer according to a first embodiment; FIG. 6 is a cross-sectional view of a capacitance-type sensor according to a second embodiment; FIG. 7 is a cross-sectional view of a capacitance-type sensor according to a third embodiment; FIG. 8 is a cross-sectional view of a capacitance-type sensor according to a fourth embodiment; FIG. 9 is a cross-sectional view of a modified example of the capacitance-type sensor according to the first embodiment.

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The drawings of the present embodiment are merely examples, and the dimensions and shapes of each part are schematic, so the technical scope of the present invention should not be interpreted as being limited to the embodiment.

[0011] First Embodiment First, the configuration of a capacitance-type sensor 1 according to a first embodiment of the present invention will be described with reference to Figs. 1 to 5. Fig. 1 is a cross-sectional view of the capacitance-type sensor according to the first embodiment. Fig. 2 is a plan view of a top layer according to the first embodiment. Fig. 3 is a plan view of a diaphragm layer according to the first embodiment. Fig. 4 is a plan view of an electrode layer according to the first embodiment. Fig. 5 is a plan view of an electrode layer according to the first embodiment.

[0012] The components of the capacitance sensor 1 are described below. For the sake of clarity and understanding of the positional relationships between the various components, each drawing may be accompanied by a Cartesian coordinate system consisting of an X-axis, a Y-axis, and a Z-axis. The directions parallel to the X-axis, the Y-axis, and the Z-axis are referred to as the X-axis, the Y-axis, and the Z-axis, respectively. The plane defined by the X-axis and the Y-axis is referred to as the XY plane. For the sake of convenience, the positive Z-axis direction (the direction of the arrow) will be referred to as the top or upper side, and the negative Z-axis direction (the direction opposite to the arrow) will be referred to as the bottom or lower side, but the orientation of the capacitance sensor 1 is not limited to this.

[0013] The capacitance sensor 1 is a device manufactured using MEMS technology. The capacitance sensor 1 includes a bottom layer 10, a bonding layer 20, an electrode layer 30, a diaphragm layer 50, an etching stopper layer 60, and a top layer 70. The capacitance sensor 1 is a capacitance-type tactile sensor that detects forces in, for example, the X-axis, Y-axis, and Z-axis directions by detecting changes in capacitance formed by the electrode layer 30. The bottom layer 10, the bonding layer 20, the electrode layer 30, the diaphragm layer 50, the etching stopper layer 60, and the top layer 70 are stacked in this order in the Z-axis direction. The electrode layer 30 is bonded to the bottom layer 10 via the bonding layer 20. The diaphragm layer 50 is directly bonded to the electrode layer 30. The top layer 70 is bonded to the diaphragm layer 50 via the etching stopper layer 60. The electrode layer 30 and the diaphragm layer 50 are directly bonded to each other using single-crystal silicon. Between the bottom layer 10 and the electrode layer 30, and between the electrode layer 30 and the diaphragm layer 50, there are formed movable spaces in which the electrodes 33, which will be described later, can move.

[0014] The bottom layer 10 corresponds to the handle substrate of the capacitance-type sensor 1. The bottom layer 10 has a glass substrate 11, internal electrodes 12, through electrodes 13, external electrodes 14, and an insulating film 15.

[0015] The glass substrate 11 has an upper surface 11A provided on the side facing the electrode layer 30 and a lower surface 11B provided on the opposite side to the upper surface 11A. The glass substrate 11 is a flat substrate, and the upper surface 11A and the lower surface 11B extend along the XY plane. The upper surface 11A and the lower surface 11B correspond to a pair of main surfaces of the glass substrate 11. The glass substrate 11 is made of silicon oxide (e.g., SiO ２ The glass substrate 11 is formed of glass containing SiO as a main component. Here, the main component of the glass refers to a component that accounts for 50 mass % or more of all components that make up the glass. For example, the glass substrate 11 is made of SiO ２ It is made of silicate glass whose main component is

[0016] The internal electrode 12 is electrically connected to the electrode layer 30 or forms a capacitance between the internal electrode 12 and the electrode layer 30. The internal electrode 12 is provided on the upper surface 11A of the glass substrate 11. The internal electrode 12 has a single-layer structure made of, for example, aluminum (Al), but is not limited to this. The internal electrode 12 may include a layer made of, for example, gold (Au), silver (Ag), copper (Cu), titanium (Ti), germanium (Ge), molybdenum (Mo), aluminum (Al), silicon (Si), or an alloy thereof. The internal electrode 12 may also have a multilayer structure including two or more conductive layers.

[0017] The through electrodes 13 electrically connect the internal electrodes 12 and the external electrodes 14. The through electrodes 13 are provided to penetrate the glass substrate 11 in the Z-axis direction. The through electrodes 13 are made of, for example, silicon (Si), but are not limited to this. The through electrodes 13 may also be made of, for example, gold (Au), silver (Ag), copper (Cu), titanium (Ti), germanium (Ge), molybdenum (Mo), aluminum (Al), silicon (Si), or an alloy thereof.

[0018] The external electrode 14 is an electrode for electrically connecting the capacitance sensor 1 to an external circuit. The external electrode 14 is provided on the lower surface 11B of the glass substrate 11. The external electrode 14 has a single-layer structure made of, for example, aluminum (Al), but is not limited to this. The external electrode 14 may include a layer made of, for example, gold (Au), silver (Ag), copper (Cu), titanium (Ti), germanium (Ge), molybdenum (Mo), aluminum (Al), silicon (Si), or an alloy thereof. The external electrode 14 may also have a multi-layer structure including two or more conductive layers.

[0019] The insulating film 15 suppresses short circuits of the external electrodes 14. The insulating film 15 is provided on the lower surface 11B of the glass substrate 11. The insulating film 15 covers the ends of the external electrodes 14, leaving parts of the external electrodes 14 exposed. The insulating film 15 is made of an insulating material. The insulating film 15 may also function as a buffer material that absorbs external impacts and suppresses damage to the glass substrate 11.

[0020] The bonding layer 20 bonds and electrically connects the bottom layer 10 and the electrode layer 30. The bonding layer 20 forms a movable space on the negative Z-axis direction side for an electrode 33 of the electrode layer 30, which will be described later. That is, the thickness of the bonding layer 20 in the Z-axis direction (hereinafter simply referred to as "thickness") corresponds to the movable range of the electrode 33 on the negative Z-axis direction side. The bonding layer 20 is made of, for example, an Al-Ge-Ti eutectic alloy containing aluminum, germanium, and titanium, but is not limited thereto. The bonding layer 20 may also be made of an Al-Si eutectic alloy containing aluminum and silicon, an Au-Sn eutectic alloy containing gold and tin, or an Au-Si eutectic alloy containing gold and silicon.

[0021] The bonding layer 20 has bonding portions 21 and 22. The bonding portion 21 connects a portion of the electrode layer 30 to ground. The bonding portion 21 bonds an outer edge portion 35 of the electrode layer 30, which will be described later, to the glass substrate of the bottom layer 10. The bonding portion 21 is electrically connected to an internal electrode 12, which is connected to a ground electrode. The bonding portion 22 electrically connects an electrode 33 of the electrode layer 30 to an external circuit. The bonding portion 22 bonds an outer edge portion 35 of the electrode layer 30, which will be described later, to the glass substrate of the bottom layer 10. The bonding portion 22 is electrically connected to the internal electrode 12, which is connected to the external circuit.

[0022] In a plan view from the Z-axis direction (hereinafter simply referred to as "plan view"), the joint 21 is provided in a frame shape along the outer edge of the capacitance-type sensor 1. In the plan view, the joint 22 is provided in the area surrounded by the joint 21. The joint 21 corresponds to a sealing frame that seals the movable space of the electrode 33, which will be described later.

[0023] The electrode layer 30 forms a capacitance that changes based on a force acting on the capacitance-type sensor 1. The electrode layer 30 is provided by a silicon substrate 31. The silicon substrate 31 is formed, for example, from a single crystal of p-type silicon (Si). The silicon substrate 31 may contain boron (B) or the like as a p-type dopant. The resistance value of the silicon (Si) used in the silicon substrate 31 is, for example, about 10 mΩ·cm.

[0024] The electrode layer 30 has a force-receiving portion 32, a plurality of electrodes 33, and an outer edge portion 35. A cavity 40 is formed on the diaphragm layer 50 side of the plurality of electrodes 33 in the electrode layer 30. That is, the silicon substrate 31 is provided with a recess in the electrode 33 that opens toward the diaphragm layer 50. The cavity 40 forms a movable space on the positive Z-axis direction side for the electrode 33 of the electrode layer 30. That is, the depth of the cavity 40 in the Z-axis direction (hereinafter simply referred to as "depth") corresponds to the movable range of the electrode 33 on the positive Z-axis direction side. The cavity 40 also corresponds to the movable range on the negative Z-axis direction side for a diaphragm portion 53 of the diaphragm layer 50 (described later).

[0025] The force receiving portion 32 receives a force acting on a boss portion 72 of the top layer 70, which will be described later, and displaces the electrode 33. As shown in Fig. 4, in a plan view, the force receiving portion 32 is provided in the center of the electrode layer 30. As shown in Fig. 1, the force receiving portion 32 is directly bonded to a transmission portion 52 of the diaphragm layer 50, which will be described later, and is separated from the bottom layer 10.

[0026] The multiple electrodes 33 form a capacitance that changes based on the force acting on a boss portion 72 of the top layer 70 (described later). Each of the multiple electrodes 33 is configured to be displaceable in the X-axis, Y-axis, or Z-axis direction based on the force acting on the boss portion 72 of the top layer 70. The capacitance formed by the electrode 33 changes due to the displacement of the electrode 33 based on the force acting on the boss portion 72 of the top layer 70. As shown in FIG. 4 , the electrodes 33 are, for example, comb-shaped electrodes arranged in the X-axis or Y-axis direction. The capacitance formed by the electrodes 33 is formed between the electrodes 33. The multiple electrodes 33 are connected to the force receiving portion 32 and the outer edge portion 35 and are provided between the force receiving portion 32 and the outer edge portion 35 in the XY plane direction. As shown in FIG. 1 , the multiple electrodes 33 are separated from both the bottom layer 10 and the diaphragm layer 50.

[0027] The electrode 33 may be a flat electrode having a main surface along the XY plane. The capacitance formed by the electrode 33 may be formed between the electrode 33 and the internal electrode 12 of the bottom layer 10, or may be formed between the electrode 33 and the diaphragm layer 50.

[0028] The outer edge portion 35 holds the electrodes 33. As shown in Fig. 4, in a plan view, the outer edge portion 35 is provided in a frame shape along the outer edge of the capacitance-type sensor 1. As shown in Fig. 1, the outer edge portion 35 is bonded to the bottom layer 10 via the bonding layer 20, and is directly bonded to an outer edge portion 55 of the diaphragm layer 50, which will be described later.

[0029] A hole SL4 is formed in the outer edge portion 35. As shown in FIG. 1, the hole SL4 penetrates the silicon substrate 31 in the Z-axis direction. As shown in FIG. 5, the hole SL4 is formed in a slit shape. Also, as shown in FIGS. 1 and 5, the hole SL4 electrically separates the portion of the electrode layer 30 connected to the electrode 33 from the portion of the electrode layer 30 connected to ground. The hole SL4 is an example of a fourth hole.

[0030] The diaphragm layer 50 deforms based on a force acting on the capacitance sensor 1. The diaphragm layer 50 also isolates the cavity 40 from the outside air. The diaphragm layer 50 is provided by a silicon substrate 51. The silicon substrate 51 is formed, for example, from a single crystal of p-type silicon (Si). The silicon substrate 51 may contain boron (B) or the like as a p-type dopant. The resistance value of the silicon (Si) used in the silicon substrate 51 is, for example, about 10 mΩ·cm.

[0031] The diaphragm layer 50 has a transmission portion 52, a diaphragm portion 53, and an outer edge portion 55. The transmission portion 52, the diaphragm portion 53, and the outer edge portion 55 of the diaphragm layer 50 have approximately the same thickness.

[0032] The transmission portion 52 receives a force acting on a boss portion 72 of the top layer 70, which will be described later, and transmits the force to the force receiving portion 32 of the electrode layer 30. As shown in FIG. 3 , in a plan view, the transmission portion 52 is provided in the center of the diaphragm layer 50, and is an area that overlaps with the boss portion 72 of the diaphragm layer 50. As shown in FIG. 1 , the transmission portion 52 is directly bonded to the force receiving portion 32 of the electrode layer 30, and is bonded to the boss portion 72 of the top layer 70, which will be described later, via the etching stopper layer 60.

[0033] A hole SL1 is formed in the transmission portion 52. As shown in FIG. 1, the hole SL1 penetrates the silicon substrate 51 in the Z-axis direction. As shown in FIG. 3, the hole SL1 is formed in a slit shape. Also, as shown in FIG. 3, in a plan view, the hole SL1 is provided in a frame shape inside a boss portion 72 of the top layer 70, which will be described later. The portion of the transmission portion 52 surrounded by the hole SL1 and the portion of the transmission portion 52 outside the hole SL1 are connected by the boss portion 72. The hole SL1 is an example of a first hole.

[0034] The hole SL1 is not limited to a hole that penetrates the silicon substrate 51 in the Z-axis direction, but may be open to at least one of the positive and negative Z-axis directions of the silicon substrate 51. In plan view, the hole SL1 is formed, for example, in a rectangular frame shape, but is not limited thereto. The hole SL1 may be formed, for example, in a polygonal frame shape, a circular frame shape, an elliptical frame shape, or a frame shape combining these shapes. The hole SL1 may not be frame-shaped, but may be formed in the shape of multiple slits spaced apart from each other. As an example, in plan view, the transmission unit 52 may be formed with a slit-shaped hole SL1 extending in the X-axis direction and a slit-shaped hole SL1 extending in the Y-axis direction, spaced apart from each other. In plan view, the hole SL1 is not limited to a slit-shaped hole, but may be formed, for example, in a dot-like shape. As an example, the transmission portion 52 may be formed with a plurality of dot-like holes SL1 aligned in the X-axis direction and a plurality of dot-like holes SL1 aligned in the Y-axis direction.

[0035] The diaphragm portion 53 deforms based on a force acting on a boss portion 72 of the top layer 70, which will be described later. As shown in FIG. 1, the diaphragm portion 53 is provided in a film shape and is configured to be flexible and deformable. As shown in FIG. 3, the diaphragm portion 53 connects a boss portion 72 and an outer edge portion 75 of the top layer 70, which will be described later, and covers the gap between the boss portion 72 and the outer edge portion 75. As shown in FIG. 1, the diaphragm portion 53 is bonded to the boss portion 72 and the outer edge portion 75 of the top layer 70, which will be described later, via an etching stopper layer 60, and is separated from the electrode layer 30 via a cavity 40.

[0036] The outer edge portion 55 holds the diaphragm portion 53. As shown in Fig. 3 , in a plan view, the outer edge portion 55 is provided in a frame shape along the outer edge of the capacitance-type sensor 1. As shown in Fig. 1 , the outer edge portion 55 is bonded to an outer edge portion 75 of the top layer 70 (described later) via an etching stopper layer 60, and is directly bonded to an outer edge portion 35 of the electrode layer 30.

[0037] A hole SL3 is formed in the outer edge portion 55. As shown in FIG. 1, the hole SL3 penetrates the silicon substrate 31 in the Z-axis direction. A portion of the hole SL3 communicates with the hole SL4. As shown in FIG. 3, the hole SL3 is formed in a slit shape. Also, as shown in FIG. 3, the hole SL3 is formed in a frame shape in a plan view. Also, as shown in FIGS. 1 and 3, the hole SL3 electrically separates the portion of the diaphragm layer 50 connected to the electrode 33 from the portion of the diaphragm layer 50 connected to ground. The hole SL3 is an example of a third hole.

[0038] As shown in a modified example in FIG. 9 , at least some of the holes SL3 may be formed so as to penetrate a portion of the frame-shaped outer edge 55 in the XY plane, thereby opening the cavity 40 to the atmosphere. That is, in a plan view, at least some of the holes SL3 may circumferentially divide the frame-shaped outer edge 55. When the cavity 40 is open to the atmosphere through the holes SL3, the degree of vacuum inside the capacitance-type sensor 1 is approximately equal to the degree of vacuum outside the capacitance-type sensor 1. When the degree of vacuum inside and outside the capacitance-type sensor 1 is approximately equal, pressure caused by differences in the degree of vacuum is not applied to the boss 72 or the diaphragm 53. This ensures that the detected capacitance value is the same even in locations with different external air pressures (e.g., high and low altitudes). This reduces fluctuations in the detection accuracy of the capacitance-type sensor 1 due to the external environment, enabling highly accurate detection of forces acting on the boss 72. In addition, the hole for opening the cavity 40 to the outside air is not limited to that formed in the outer edge portion 55, but may be formed, for example, in the outer edge portion 75, the outer edge portion 35, the outer edge portion 75, or the joint portions 21 and 22.

[0039] The etching stopper layer 60 is provided to stop the etching of the silicon substrate 51 of the diaphragm layer 50 or the etching of the silicon substrate 71 of the top layer 70, which will be described later. For example, the etching stopper layer 60 inhibits the progression of the etching in the Z-axis direction when the silicon substrate 51 is etched to form the holes SL1 and SL3. Furthermore, for example, the etching stopper layer 60 inhibits the progression of the etching in the Z-axis direction when the silicon substrate 71 is etched to form a gap between a boss portion 72 and an outer edge portion 75 of the top layer 70, which will be described later. Specifically, when the silicon substrate 51 and the silicon substrate 71 are bonded together via the etching stopper layer 60 and the silicon substrate 51 or the silicon substrate 71 is etched by deep reactive ion etching (DRIE) or the like, the silicon oxide of the etching stopper layer 60 does not react with etching species that react with silicon, and therefore, once the silicon substrate 51 or the silicon substrate 71 has been penetrated, the progress of the etching in the Z-axis direction is hindered.

[0040] The etching stopper layer 60 also electrically insulates the diaphragm layer 50 from the top layer 70. Electrically insulating the diaphragm layer 50 from the top layer 70 improves the reliability of the capacitance-type sensor 1. Because the top layer 70 is the point of contact between the capacitance-type sensor 1 and the outside, there is a possibility that external charges may flow into the top layer 70. However, the etching stopper layer 60 electrically insulates the top layer 70 from the diaphragm layer 50, preventing charges that flow into the top layer 70 from flowing into the diaphragm layer 50 or the electrode layer 30. This prevents sticking or melting of the electrode 33 due to the charge flow. The etching stopper layer 60 is provided over substantially the entire surface of the capacitance-type sensor 1 in the XY plane. The etching stopper layer 60 is made of silicon oxide. The etching stopper layer 60 is provided by, for example, thermal oxidation of the silicon substrate 51 or the silicon substrate 71, but is not limited to this and may be provided by sputtering, CVD (Chemical Vapor Deposition), or the like.

[0041] The top layer 70 constitutes a detection surface that detects a force acting on the capacitance-type sensor 1. The top layer 70 is provided by a silicon substrate 71. The silicon substrate 71 is formed, for example, from a single crystal of p-type silicon (Si). The silicon substrate 71 may contain boron (B) or the like as a p-type dopant. The resistance value of the silicon (Si) used in the silicon substrate 71 is, for example, about 10 mΩ cm.

[0042] The top layer 70 is a layer provided to displace the electrode 33 based on the force acting on the boss portion 72, and does not need to be electrically connected to the diaphragm layer 50 or the electrode layer 30. Therefore, the silicon (Si) used for the silicon substrate 71 may be high-resistivity silicon (Si) having a resistance value of, for example, 1 kΩ cm or more. This makes it possible to suppress parasitic capacitance formed between the top layer 70 and the diaphragm layer 50. Therefore, the detection sensitivity of the capacitance-type sensor 1 can be improved.

[0043] The top layer 70 has a boss portion 72 and an outer edge portion 75. The boss portion 72 and the outer edge portion 75 of the top layer have approximately the same thickness.

[0044] The boss portion 72 receives a force acting in at least one of the X-axis direction and the Y-axis direction. For example, when the boss portion 72 receives a force F in the positive direction of the X-axis, the force receiving portion 32 receives a force in the negative direction of the X-axis, with the fulcrum P as the fulcrum, and the electrode 33 is displaced by a displacement D in the negative direction of the X-axis. The position of the fulcrum P is determined by the thickness of the boss portion 72, the thickness of the transmission portion 52, the thickness of the force receiving portion 32, the depth of the hole SL1, and the like. As shown in FIG. 2 , the boss portion 72 is provided in the center of the top layer 70 in a plan view.

[0045] The outer edge portion 75 connects the region outside the hole portion SL3 to the region inside the hole portion SL3 in a plan view of the outer edge portion 55 of the diaphragm layer 50. As shown in FIG. 2 , the outer edge portion 75 is provided in a frame shape along the outer edge of the capacitance-type sensor 1 in a plan view. The outer edge portion 75 is provided at a distance from the boss portion 72 in the XY plane directions. The gap between the boss portion 72 and the outer edge portion 75 is provided in a frame shape. In other words, the outer edge portion 75 is separated from the boss portion 72 in all directions in the XY plane directions.

[0046] It should be noted that the outer edge portion 75 is not limited to being separated from the boss portion 72 in all directions. The outer edge portion 75 may be connected to the boss portion 72 in at least some directions within the XY plane. For example, the outer edge portion 75 may be connected to the boss portion 72 by a thin-walled connecting portion that is thinner than the boss portion 72 and the outer edge portion 75. Furthermore, for example, the outer edge portion 75 may be connected to the boss portion 72 by a beam-shaped connecting portion that extends in a predetermined direction within the XY plane. However, from the viewpoint of improving the mobility of the boss portion 72, it is desirable that the outer edge portion 75 be separated from the boss portion 72 in all directions.

[0047] As described above, the capacitance-type sensor 1 according to this embodiment includes a top layer 70, a diaphragm layer 50, and an electrode layer 30, which are stacked in this order in the Z-axis direction. The top layer 70 has a boss portion 72 that receives a force acting in at least one of the X-axis and Y-axis directions. The diaphragm layer 50 deforms based on the force acting on the boss portion 72. The electrode layer 30 has an electrode 33 that forms a capacitance that changes based on the force acting on the boss portion 72. A hole SL1 that opens in the Z-axis direction is formed in the region of the diaphragm layer 50 that overlaps with the boss portion 72.

[0048] This improves the flexibility of the diaphragm layer 50, which improves the mobility of the boss portion 72 when a force F is applied, thereby increasing the displacement D of the electrode 33. This increases the change in capacitance formed by the electrode 33, thereby improving the detection accuracy of the capacitance-type sensor 1.

[0049] In one embodiment of the above, the hole SL1 is formed in a slit shape.

[0050] This allows the flexibility of the diaphragm layer 50 to be further improved compared to when the holes SL1 are formed in a dotted pattern.

[0051] In one aspect of the above, the hole portion SL1 is formed in a frame shape.

[0052] This can improve the flexibility of the diaphragm layer 50 in the X-axis direction, the Y-axis direction, and the Z-axis direction.

[0053] In one aspect of the above, the capacitance type sensor 1 further includes an etching stopper layer 60 provided between the top layer 70 and the diaphragm layer 50, the top layer 70 and the diaphragm layer 50 being made of silicon, and the etching stopper layer 60 being made of silicon oxide.

[0054] This prevents the silicon substrate 51 from being removed by etching, for example, when the silicon substrate 71 of the top layer 70 and the silicon substrate 51 of the diaphragm layer 50 are bonded together via the etching stopper layer 60 and then the silicon substrate 71 is etched to form the boss portion 72 and the outer edge portion 75. Conversely, when the silicon substrate 51 is etched to form the holes SL1 and SL3, the silicon substrate 71 is prevented from being removed by etching. Furthermore, since the diaphragm layer 50 and the top layer 70 are electrically insulated by the etching stopper layer 60, the inflow of charge from the outside into the diaphragm layer 50 and the electrode layer 30 via the top layer 70 is suppressed. This prevents sticking and melting of the electrodes 33 of the electrode layer 30, thereby improving the reliability of the capacitance-type sensor 1.

[0055] In one embodiment of the above, the electrode layer 30 is provided by a silicon substrate 31, the diaphragm layer 50 is provided by a silicon substrate 51, and the electrode layer 30 and the diaphragm layer 50 are directly bonded to each other.

[0056] This allows the diaphragm layer 50 to be electrically connected to the electrode layer 30 without using a through electrode or the like, which is expensive to manufacture.

[0057] In one aspect of the above, a hole portion SL3 is formed in the diaphragm layer 50, penetrating the silicon substrate 51 in the Z-axis direction, and a hole portion SL4 is formed in the electrode layer 30, penetrating the silicon substrate 31 in the Z-axis direction and communicating with the hole portion SL3.

[0058] According to this, the diaphragm layer 50 can be divided into a plurality of parts by the holes SL3, and each of the plurality of parts of the diaphragm layer 50 can be set to a different potential. In addition, the electrode layer 30 can be divided into a plurality of parts by the holes SL4, and each of the plurality of parts of the electrode layer 30 can be set to a different potential.

[0059] As one aspect of the above, the hole portion SL3 may be formed in a frame shape surrounding a part of the diaphragm layer 50.

[0060] This allows the portion of the diaphragm layer 50 surrounded by the hole SL3 and the portion outside the hole SL3 to be at different potentials. For example, if the portion of the diaphragm layer 50 surrounded by the hole SL3 is joined to a portion of the electrode layer 30 connected to the electrode 33, the portion of the diaphragm layer 50 surrounded by the hole SL3 can be electrically connected to the electrode 33, while the portion of the diaphragm layer 50 outside the hole SL3 can be connected to ground.

[0061] As one aspect of the above, the hole SL3 penetrates the outer edge 55 of the diaphragm layer 50 in the XY plane direction, opening the cavity 40 to the outside air.

[0062] With this, the degree of vacuum inside the capacitance sensor 1 and the degree of vacuum outside the capacitance sensor 1 are approximately equal, so pressure caused by differences in the degree of vacuum is not applied to the boss portion 72 or the diaphragm portion 53. Therefore, the detected capacitance value is the same even in places with different external air pressures (for example, high and low places). In other words, it is possible to suppress fluctuations in the detection accuracy of the capacitance sensor 1 due to the external environment, and it becomes possible to detect the force acting on the boss portion 72 with high accuracy.

[0063] In one embodiment of the above, the cavity 40 is formed on the diaphragm layer 50 side of the electrode layer 30 .

[0064] This allows the distance from the fulcrum P to the electrode 33 to be adjusted by the depth of the cavity 40, thereby increasing the displacement D of the electrode 33. This increases the change in capacitance formed by the electrode 33, thereby improving the detection accuracy of the capacitance-type sensor 1.

[0065] In one embodiment of the above, the electrode 33 is a comb-teeth electrode.

[0066] This allows the detection accuracy of the capacitance type sensor 1 to be improved compared to when the electrode 33 is a flat plate electrode.

[0067] Other embodiments will be described below. Note that components that are the same as or similar to those in the first embodiment are denoted by the same or similar reference numerals, and descriptions thereof will be omitted as appropriate. Furthermore, similar effects resulting from similar components will not be mentioned one after another.

[0068] Second Embodiment Next, the structure of a capacitance-type sensor 2 according to a second embodiment will be described with reference to Fig. 6. Fig. 6 is a cross-sectional view of the capacitance-type sensor 2 according to the second embodiment.

[0069] A hole SL2 is formed in the boss portion 272 of the top layer 270. A hole SL5 is formed in the outer edge portion 275 of the top layer 270. The hole SL2 opens in the Z-axis direction and communicates with the hole SL1. The hole SL5 opens in the Z-axis direction and communicates with the hole SL3. The holes SL2 and SL5 are bottomed holes that open toward the diaphragm layer 50. The hole SL2 is formed in a slit shape extending in the X-axis direction and the Y-axis direction, and is formed in a frame shape along the hole SL1 in a plan view. The hole SL5 is formed in a slit shape extending in the X-axis direction and the Y-axis direction, and is formed in a frame shape along the hole SL3 in a plan view. The hole SL2 is an example of a second hole, and the hole SL5 is an example of a fifth hole.

[0070] The boss portion 272 has a leaf spring portion LS1. The leaf spring portion LS1 is located outside the hole portion SL2 in the XY plane. The leaf spring portion LS1 is a plate-shaped portion between the outer surface of the boss portion 272 and the hole portion SL2 in the XY plane. When a force in the X-axis direction acts on the boss portion 272, the leaf spring portion LS1 having a main surface extending in the YZ plane bends and deforms in the X-axis direction, providing a restoring force to the boss portion 272 and the electrode 33. The thickness in the X-axis direction of the leaf spring portion LS1 having such a main surface extending in the YZ plane is smaller than the thickness in the Z-axis direction of the diaphragm layer 50. Furthermore, when a force in the Y-axis direction acts on the boss portion 272, the leaf spring portion LS1 having a main surface extending in the ZX plane bends and deforms in the Y-axis direction, providing a restoring force to the boss portion 272 and the electrode 33. The thickness in the Y-axis direction of the leaf spring portion LS1 having such a main surface extending in the ZX plane direction is smaller than the thickness in the Z-axis direction of the diaphragm layer 50.

[0071] As described above, in the capacitance-type sensor 2 according to this embodiment, the boss 272 has a hole SL2 formed therein, which communicates with the hole SL1. This improves the flexibility of the top layer 270, thereby improving the mobility of the boss 272 when a force is applied to the boss 272 and increasing the displacement of the electrode 33. This increases the change in capacitance formed by the electrode 33, thereby improving the detection accuracy of the capacitance-type sensor 2.

[0072] In one embodiment of the above, the hole SL2 is formed in a slit shape.

[0073] This allows the flexibility of the top layer 270 to be further improved compared to when the holes SL2 are formed in a dotted pattern.

[0074] In one embodiment of the above, the hole SL2 is formed in a frame shape.

[0075] This can improve the flexibility of the top layer 270 in the X-axis direction, the Y-axis direction, and the Z-axis direction.

[0076] As one aspect of the above, the thickness of the leaf spring portion LS1 in the direction of bending deformation of the leaf spring portion LS1 is smaller than the thickness of the diaphragm layer 50.

[0077] This can further improve the flexibility of the top layer 270.

[0078] Third Embodiment Next, the structure of a capacitance-type sensor 3 according to a third embodiment will be described with reference to Fig. 7. Fig. 7 is a cross-sectional view of the capacitance-type sensor 3 according to the third embodiment.

[0079] A cavity 340 is formed on the electrode layer 330 side of the diaphragm layer 350 of the capacitance sensor 3. The diaphragm layer 350 is recessed in a diaphragm portion 353 that opens to the electrode layer 330 side. In the diaphragm layer 350, the thickness of the diaphragm portion 353 is smaller than the thicknesses of the transmission portion 52 and the outer edge portion 55. In the electrode layer 330 of the capacitance sensor 3, the thickness of the force receiving portion 32, the thickness of the electrode 333, and the thickness of the outer edge portion 35 are approximately equal to one another.

[0080] Fourth Embodiment Next, the structure of a capacitance-type sensor 4 according to a fourth embodiment will be described with reference to Fig. 8. Fig. 8 is a cross-sectional view of the capacitance-type sensor 4 according to the fourth embodiment.

[0081] In the capacitance-type sensor 4, the ends of the electrode layer 430, the diaphragm layer 450, and the etching stopper layer 460 in the XY plane are located more inward than the ends of the bottom layer 10 and the top layer 470 in the XY plane. A recess RC5 having the same depth as the hole SL5 is formed in the outer edge 475 of the top layer 470. The recess RC5 is open to the outside in the XY plane and toward the negative Z-axis direction.

[0082] According to this, when an aggregate substrate on which a plurality of connected capacitance sensors 4 are diced to separate the capacitance sensors 4, the dicing depth is small, which makes it possible to reduce the occurrence of defective products. Furthermore, when the capacitance sensors 4 are separated by laser dicing, the dicing speed can be improved, thereby reducing the dicing cost.

[0083] Some or all of the embodiments of the present invention will be described below, but the present invention is not limited to the following descriptions.

[0084] <1> A capacitance-type sensor comprising: a top layer having a boss portion that receives a force acting in at least one direction out of a first direction and a second direction intersecting the first direction; a diaphragm layer that is stacked on the top layer in a third direction intersecting the first and second directions and that deforms based on the force acting on the boss portion; and an electrode layer that is stacked on the diaphragm layer in the third direction and has an electrode for forming a capacitance that changes based on the force acting on the boss portion, wherein a first hole portion that opens in the third direction is formed in a region of the diaphragm layer that overlaps with the boss portion.

[0085] <2> The capacitance-type sensor according to <1>, wherein the boss portion of the top layer has a second hole portion that opens in a third direction, and the second hole portion communicates with the first hole portion.

[0086] <3> The capacitance-type sensor according to <2>, wherein the first hole portion and the second hole portion are formed in a slit shape extending in the first direction or the second direction.

[0087] <4> The capacitance-type sensor according to <3>, wherein the first hole and the second hole are formed in a frame shape when viewed from a third direction.

[0088] <5> The capacitance-type sensor according to any one of <2> to <4>, wherein the boss portion has a leaf spring portion located outside the second hole portion, and the thickness of the leaf spring portion in a direction in which the leaf spring portion bends and deforms based on a force acting on the boss portion is smaller than the thickness of the diaphragm layer in the third direction.

[0089] <6> The capacitance-type sensor according to any one of <1> to <5>, further comprising an etching stopper layer provided between the top layer and the diaphragm layer, wherein the top layer and the diaphragm layer are made of silicon, and the etching stopper layer is made of silicon oxide.

[0090] <7> The capacitance-type sensor according to <6>, wherein the electrode layer is made of silicon, and the diaphragm layer and the electrode layer are directly bonded to each other.

[0091] <8> The capacitance-type sensor according to <7>, wherein the diaphragm layer is formed with a third hole portion penetrating the diaphragm layer in a third direction, and the electrode layer is formed with a fourth hole portion penetrating the electrode layer and communicating with the third hole portion.

[0092] <9> The capacitance-type sensor according to <8>, wherein the third hole portion is formed in a frame shape surrounding a part of the diaphragm layer.

[0093] <10> The capacitance-type sensor according to <8> or <9>, wherein the diaphragm layer has an outer edge portion provided in a frame shape along the outer edge portion of the diaphragm layer in a planar view from the third direction, and the third hole portion penetrates the outer edge portion of the diaphragm layer in a direction along a plane including the first direction and the second direction, and opens a cavity formed between the electrode layer and the diaphragm layer to the outside air.

[0094] <11> The capacitance-type sensor according to any one of <1> to <10>, wherein a cavity is formed on the diaphragm layer side of the electrode layer.

[0095] <12> The capacitance-type sensor according to any one of <1> to <11>, wherein the electrodes are comb-shaped electrodes.

[0096] <13> The capacitance-type sensor according to any one of <1> to <12>, wherein the top layer further has an outer edge portion provided in a frame shape along the outer edge portion of the top layer in a plan view from the third direction, the diaphragm layer has a third hole portion formed therein that penetrates the diaphragm layer in the third direction, and the outer edge portion of the top layer has a fifth hole portion with a bottom that communicates with the third hole portion, and a recess that has the same dimension in the third direction as the fifth hole portion and opens to the outer edge portion.

[0097] As described above, according to one aspect of the present invention, it is possible to provide a capacitance-type sensor that can improve detection sensitivity.

[0098] The above-described embodiments are intended to facilitate understanding of the present invention and are not intended to limit the present invention. The present invention may be modified or improved without departing from its spirit, and such modifications and improvements are also included within the scope of the present invention. In other words, designs modified by those skilled in the art as appropriate are also encompassed within the scope of the present invention as long as they incorporate the characteristics of the present invention. For example, the elements of the present embodiments, as well as their arrangement, materials, conditions, shapes, sizes, etc., are not limited to those exemplified and can be modified as appropriate. Furthermore, the elements of the present embodiments can be combined to the extent technically possible, and such combinations are also encompassed within the scope of the present invention as long as they incorporate the characteristics of the present invention.

[0099] DESCRIPTION OF SYMBOLS 1...Capacitive sensor 10...Bottom layer 11...Glass substrate 20...Joint layer 30...Electrode layer 31...Silicon substrate 32...Force receiving portion 33...Electrode 35...Outer edge portion 40...Cavity 50...Diaphragm layer 51...Silicon substrate 52...Transmission portion 53...Diaphragm portion 55...Outer edge portion 60...Etching stopper layer 70...Top layer 71...Silicon substrate 72...Boss portion 75...Outer edge portion SL1 to SL5...Hole portion F...Force P...Fulcrum D...Displacement

Claims

1. A capacitance-type sensor comprising: a top layer having a boss portion that receives a force acting in at least one of a first direction and a second direction intersecting the first direction; a diaphragm layer that is laminated on the top layer in a third direction intersecting the first and second directions and that deforms based on the force acting on the boss portion; and an electrode layer that is laminated on the diaphragm layer in the third direction and has electrodes that form a capacitance that changes based on the force acting on the boss portion, wherein a first hole portion that opens in the third direction is formed in the area of ​​the diaphragm layer that overlaps with the boss portion.

2. The capacitance type sensor according to claim 1, wherein a second hole portion that opens in the third direction is formed in the boss portion of the top layer, and the second hole portion communicates with the first hole portion.

3. The capacitance type sensor according to claim 2, wherein the first hole portion and the second hole portion are formed in the shape of a slit extending in the first direction or the second direction.

4. The capacitance type sensor according to claim 3, wherein the first hole portion and the second hole portion are formed in a frame shape when viewed in a plan view from the third direction.

5. A capacitance-type sensor as claimed in any one of claims 2 to 4, wherein the boss portion has a leaf spring portion located outside the second hole portion, and the thickness of the leaf spring portion in the direction in which the leaf spring portion bends and deforms based on the force acting on the boss portion is smaller than the thickness of the diaphragm layer in the third direction.

6. The capacitance type sensor according to any one of claims 1 to 5, further comprising an etching stopper layer provided between the top layer and the diaphragm layer, the top layer and the diaphragm layer being made of silicon, and the etching stopper layer being made of silicon oxide.

7. The capacitance type sensor according to claim 6, wherein the electrode layer is made of silicon, and the diaphragm layer and the electrode layer are directly bonded to each other.

8. A capacitance-type sensor as described in claim 7, wherein the diaphragm layer is formed with a third hole portion that penetrates the diaphragm layer in the third direction, and the electrode layer is formed with a fourth hole portion that penetrates the electrode layer and communicates with the third hole portion.

9. The capacitance type sensor according to claim 8, wherein the third hole portion is formed in a frame shape surrounding a part of the diaphragm layer.

10. A capacitance type sensor as described in claim 8 or 9, wherein the diaphragm layer has an outer edge portion formed in a frame shape along the outer edge portion of the diaphragm layer when viewed in a plane from the third direction, and the third hole portion penetrates the outer edge portion of the diaphragm layer in a direction along a plane including the first direction and the second direction, and opens a cavity formed between the electrode layer and the diaphragm layer to the outside air.

11. The capacitance type sensor according to any one of claims 1 to 10, wherein a cavity is formed on the electrode layer on the side of the diaphragm layer.

12. The capacitance type sensor according to any one of claims 1 to 11, wherein the electrodes are comb electrodes.

13. A capacitance-type sensor as described in any one of claims 1 to 12, wherein the top layer further has an outer edge portion formed in a frame shape along the outer edge portion of the top layer when viewed in a plane from the third direction, the diaphragm layer has a third hole portion formed therein that penetrates the diaphragm layer in the third direction, and the outer edge portion of the top layer has a fifth hole portion with a bottom that communicates with the third hole portion, and a recess that has the same dimension in the third direction as the fifth hole portion and opens to the outer edge portion.

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