JP6515477B2 - Mechanical quantity sensor and mechanical quantity measuring device - Google Patents

Description

  The present invention relates to a dynamic quantity sensor.

  BACKGROUND A pressure sensor is known that measures pressure by converting the deflection of a membrane caused by the pressure difference between two spaces separated by a thin film (hereinafter sometimes referred to as a membrane) into an electrical signal. For example, Patent Document 1 discloses a technique for measuring the amount of deflection of a membrane from a change in capacitance formed by using a membrane having conductivity as a diaphragm and a fixed electrode provided opposite to the membrane. It is disclosed.

JP 2008-258088 A

  Pressure sensors suitable for measuring pressure very low compared to atmospheric pressure may be exposed to a near atmospheric pressure environment when it is not necessary to make a measurement of pressure. In such a case, the membrane is pushed to the atmospheric pressure, and the membrane bends to such an extent as to come into contact with the oppositely provided fixed electrode. When the pressure sensor is returned to the low pressure measurement environment again, the membrane may be separated from the fixed electrode, but a phenomenon in which the membrane does not return with sticking (hereinafter sometimes referred to as sticking phenomenon) may occur. .

  Therefore, in order to make the sticking phenomenon less likely to occur, the contact area is reduced by arranging the stopper on the membrane so that the membrane and the electrode sandwich the stopper without contacting the membrane and the fixed electrode. Has been tried. However, since the sticking phenomenon still remains, further improvement is desired.

  One of the objects of the present invention is to suppress the sticking phenomenon of a dynamic quantity sensor.

  According to one embodiment of the present invention, a flexible portion having conductivity and flexing in response to an external force, and a fixed electrode disposed opposite to the flexible portion to form a capacitance with the flexible portion. And a stopper disposed on the fixed electrode side of the flexible portion, wherein the stopper and the fixed electrode are characterized in that a metal having a Vickers hardness of 0.5 GPa or more is disposed on the surface. Provide a quantity sensor. According to this, it is possible to suppress the sticking phenomenon of the dynamic quantity sensor.

  According to one embodiment of the present invention, a flexible portion having conductivity and flexing in response to an external force, and a fixed electrode disposed opposite to the flexible portion to form a capacitance with the flexible portion. And a stopper disposed on the flexible portion side of the fixed electrode, wherein the stopper has a metal having a Vickers hardness of 0.5 GPa or more disposed on the surface thereof. Do. According to this dynamic quantity sensor, it is possible to suppress the sticking phenomenon of the dynamic quantity sensor.

  The stopper is further disposed on the fixed electrode side of the flexible portion, and the flexible portion is the fixed electrode of the stopper disposed on the fixed electrode and the stopper disposed on the flexible portion. They may be in contact with each other if they are flexed to the side by more than a predetermined amount. According to the mechanical quantity sensor, since the stoppers formed of hard metals contact each other, it is possible to further suppress the sticking phenomenon of the mechanical quantity sensor.

  The flexible portion is a membrane in the shape of a circle, the stopper is a shape along a tangent of a concentric circle of the circle, and the stopper is a first displacement when the flexible portion is bent by a predetermined amount The first displacement amount is smaller than the second displacement amount, and the first displacement amount is smaller than the second displacement amount. The first displacement amount is smaller than the second displacement amount. The first stopper may have a larger installation area than the second stopper. According to this mechanical quantity sensor, it is possible to disperse the force due to the impact when the stopper contacts the opposing flexible portion or the fixed electrode, and it is possible to suppress the breakage of the stopper.

  The flexible portion may be a membrane in the shape of a circle, and the stopper may have a shape along a circular arc of concentric circles of the circle. According to this mechanical quantity sensor, it is possible to disperse the force due to the impact when the stopper contacts the opposing flexible portion or the fixed electrode, and it is possible to suppress the breakage of the stopper.

  The stopper may have a chamfered surface on the side where the displacement amount is maximum when the flexible portion bends. According to this mechanical quantity sensor, it is possible to disperse the force due to the impact when the stopper contacts the opposing flexible portion or the fixed electrode, and it is possible to suppress the breakage of the stopper.

  The stopper may have a plurality of regions having different heights, and the height may be lower toward the position side where the displacement amount is maximum when the flexible portion is bent. According to this mechanical quantity sensor, it is possible to disperse the force due to the impact when the stopper contacts the opposing flexible portion or the fixed electrode, and it is possible to suppress the breakage of the stopper.

  The flexible portion may be a membrane fixed at its periphery, and the external force may be generated by a pressure difference between both sides of the membrane. According to this dynamic quantity sensor, a low pressure can be measured, and the occurrence of the sticking phenomenon can be suppressed even under the environment of atmospheric pressure after the measurement.

  The stopper may have a single layer structure. According to this dynamic quantity sensor, it is possible to suppress the sticking phenomenon of the dynamic quantity sensor.

  The stopper may have a structure of two or more layers. According to this dynamic quantity sensor, it is possible to suppress the sticking phenomenon of the dynamic quantity sensor.

  The plurality of stoppers may be arranged such that the center of the distribution of the plurality of stoppers and the center of gravity of the flexible portion are at different positions. According to this dynamic quantity sensor, since the non-uniform force is applied to the flexible part, the sticking phenomenon of the dynamic quantity sensor can be further suppressed.

  According to one embodiment of the present invention, in a state where the mechanical quantity sensor described above, the flexible portion and the fixed electrode sandwich the stopper, the flexible portion and the fixed electrode are interposed between the stopper and the flexible portion. And a control unit configured to control so as to suppress a flowing current. According to this mechanical quantity measuring device, it is possible to suppress the sticking phenomenon of the mechanical quantity sensor. Further, the current flowing through the stopper can be controlled between the flexible portion and the fixed electrode.

  According to the present invention, the sticking phenomenon of the pressure sensor can be suppressed.

It is a schematic diagram of the cross-section for demonstrating the structure according to 1st Embodiment of this invention, and the operation | movement according to the external pressure. It is the top view which looked at the 1st substrate of the pressure sensor concerning a 1st embodiment of the present invention from the 2nd substrate side. It is the top view which looked at the 2nd substrate of the pressure sensor concerning a 1st embodiment of the present invention from the 1st substrate side. It is a schematic diagram of the cross-section for demonstrating the sticking phenomenon of a pressure sensor. It is a schematic diagram of the cross-section for demonstrating the manufacturing method of the 1st board | substrate of the pressure sensor which concerns on 1st Embodiment of this invention. It is a schematic diagram of the cross-section for demonstrating the manufacturing method of the 2nd board | substrate of the pressure sensor which concerns on 1st Embodiment of this invention. It is sectional drawing for demonstrating the manufacturing method of the pressure sensor after the 1st board | substrate and 2nd board | substrate which concern on 1st Embodiment of this invention are joined. It is a block diagram showing composition of a pressure measuring device using a pressure sensor concerning a 1st embodiment of the present invention. It is a schematic diagram of the cross-section for demonstrating the structure of the pressure sensor which concerns on 2nd Embodiment of this invention. It is a schematic diagram of the cross-section for demonstrating the structure of the pressure sensor which concerns on 3rd Embodiment of this invention. It is the top view which looked at the 1st substrate of the pressure sensor concerning a 4th embodiment of the present invention from the 2nd substrate side. It is the top view which looked at the 1st substrate of the pressure sensor concerning a 5th embodiment of the present invention from the 2nd substrate side. It is the top view which looked at the 1st substrate of the pressure sensor concerning a 6th embodiment of the present invention from the 2nd substrate side. It is the top view which looked at the 1st substrate of the pressure sensor concerning a 7th embodiment of the present invention from the 2nd substrate side. It is a schematic diagram of the cross-section for demonstrating the example of the other cross-sectional shape of the stopper of the pressure sensor which concerns on 8th Embodiment of this invention.

First Embodiment
Hereinafter, a pressure sensor according to a first embodiment of the present invention will be described in detail with reference to the drawings. The embodiments described below are merely examples of the embodiments of the present invention, and the present invention is not construed as being limited to these embodiments. In the drawings referred to in this embodiment, the same portions or portions having similar functions are denoted by the same reference numerals or similar reference numerals (reference numerals with A, B, etc. appended after numbers), and the repetition thereof The description of may be omitted. Further, the dimensional ratio of the drawings may be different from the actual ratio for convenience of explanation, or part of the configuration may be omitted from the drawings.

[Configuration of pressure sensor 1]
FIG. 1 is a schematic view of a structure of a pressure sensor according to a first embodiment of the present invention and a cross-sectional structure for explaining an operation according to an external pressure. The pressure sensor 1 is formed by combining the first substrate 10 and the second substrate 20. In this example, the first substrate 10 is an SOI (Silicon on Insulator) substrate. The second substrate 20 is a glass substrate.

  The first substrate 10 comprises a BOX layer 13, an active layer 15 and a support layer 17. The BOX layer 13 is silicon oxide, and the active layer 15 and the support layer 17 are silicon. The active layer 15 has conductivity and is formed thin at the central portion. This thinly formed portion is referred to as a flexible portion 151. The flexible portion 151 is a membrane whose periphery is fixed. The portion fixing the flexible portion 151 is referred to as a fixing portion 160.

  A sealed internal space 110 is formed on the surface of the flexible portion 151 on the second substrate 20 side (hereinafter referred to as the first surface 1511). The second surface 1512 of the flexible portion 151 faces the external space 1000. Therefore, the second chamber 120 is formed. The internal space 110 and the external space 1000 of the pressure sensor 1 are separated by a flexible portion 151.

  The internal space 110 is sealed by the first substrate 10 and the second substrate 20 so as to be maintained at a predetermined pressure lower than the atmospheric pressure. In this example, the internal space 110 is kept in a high vacuum state. Therefore, when the pressure in the outer space 1000 is higher than that in the inner space 110, the flexible portion 151 is bent toward the second substrate 20 so as to reduce the volume of the inner space 110, as shown in FIG. 1 (b). Well. On the other hand, when the pressure in the outer space 1000 is lower than that in the inner space 110, the flexible portion 151 is opposite to the second substrate 20 so as to expand the volume of the inner space 110, as shown in FIG. To flex.

  A stopper 155 is disposed on the first surface 1511 side of the flexible portion 151. The stopper 155 has a structure in which a metal having a Vickers Hardness of 0.5 GPa or more is disposed at least on the contact surface (surface on the electrode 255 side). Examples of such a metal include W, Mo, Ta, Ti, Ni, Cu, Al, Fe (S45C), SUS304, Ag and the like. Desirably, the Vickers hardness of the stopper 155 is a metal of 1.0 GPa or more, and in this case, W, Mo, Ta, Ti, Fe (S 45 C), SUS 304 or the like. Moreover, what combined several metal may be used. Au has a Vickers hardness of about 0.25 GPa and is softer than the above-mentioned metals.

  In addition, although the stopper 155 is the above-described metal single layer in this example, the stopper 155 may be formed of two or more layers. For example, in the case of two layers, the layer in contact with the flexible portion 151 may be a metal layer for improving adhesion with the flexible portion 151, or may be an insulating layer. Thus, when the stopper 155 has a laminated structure, it does not necessarily have to have the characteristics (including Vickers hardness) required for the material of the contact surface except for the metal disposed on the contact surface. It is desirable to have a Vickers hardness comparable to the contact surface in all of the laminations.

  In the second substrate 20, through electrodes 213, 215 penetrating the substrate are formed. Electrodes 253 and 255 are formed on the inner space 110 side of the second substrate 20, and electrodes 233 and 235 are formed on the outer space 1000 side.

  The electrode 253 is electrically connected to the active layer 15. The through electrode 213 electrically connects the electrode 253 and the electrode 233. The through electrode 215 electrically connects the electrode 255 and the electrode 235. The electrode 255 and the flexible portion 151 form a capacitance. The electrode 255 is a fixed electrode. On the other hand, when the flexible portion 151 bends, the distance between the electrodes changes, and the size of the capacitance also changes according to the amount of bending.

  Similar to the stopper 155, the electrode 255 has a structure in which a metal having a Vickers hardness of 0.5 GPa or more, preferably 1.0 GPa or more is disposed at least on the contact surface (surface on the stopper 155 side). Moreover, what combined several metal may be used. In addition, when the electrode 255 has a laminated structure, it does not necessarily have to have the characteristics (including Vickers hardness) required for the material of the contact surface except the metal disposed on the contact surface. It is desirable to have a Vickers hardness equivalent to the contact surface in all of the above.

  This capacitance value is measured by connecting the electrodes 233 and 235 to a measuring device. The amount of bending of the flexible portion 151 can be measured based on the measured capacitance value. Then, the pressure of the external space 1000 (or the pressure difference between the internal space 110 and the external space 1000) can be measured based on the amount of deflection of the flexible portion 151.

  In addition, the fixed electrode which forms a capacity | capacitance with the flexible part 151 may exist other than the electrode 255. FIG. For example, a reference electrode for correcting a change in capacitance according to an environmental change such as temperature and humidity may be provided as a fixed electrode which forms a capacitance with the flexible portion 151.

  In order to increase the degree of vacuum of the inner space 110, a getter material 260 such as a non-evaporable getter (NEG) may be disposed. By providing the getter material 260, a gas or the like generated when the first substrate 10 and the second substrate 20 are bonded by anodic bonding can be captured, and the degree of vacuum of the internal space 110 can be increased.

  FIG. 2 is a plan view of the first substrate of the pressure sensor according to the first embodiment of the present invention as viewed from the second substrate side. FIG. 3 is a plan view of the second substrate of the pressure sensor according to the first embodiment of the present invention as viewed from the first substrate side. As shown in FIG. 2, an internal space 110 is formed by the presence of a cavity whose bottom surface is a substantially square formed in the active layer 15. Further, the electrode 253 is in contact with the active layer 15 in the region 253Z.

  In addition, the flexible portion 151 is a circular film whose periphery is fixed to the fixing portion 160. Stoppers 155 are arranged along a plurality of concentric circles of the circle of the flexible portion 151. Furthermore, in this example, the stoppers 155 are arranged radially from the stopper 155X arranged at the circle center. The flexible portion 151 may come in contact with the surface of the second substrate 20 when it is significantly bent. Therefore, as shown in FIG. 2, it is desirable that the stoppers 155 be dispersedly disposed in the area SA which extends to the outside of at least the area 255 Z facing the electrode 255 within the range of the flexible portion 151.

  In the second substrate 20, the electrode 255 is disposed in the central portion, and the getter material 260 is disposed in the peripheral portion. As described above, when the reference electrode is further provided as the fixed electrode, the reference electrode is arranged, for example, to surround the periphery of the electrode 255.

[Sticking phenomenon]
Subsequently, the sticking phenomenon will be described with reference to FIG.

  FIG. 4 is a schematic view of a cross-sectional structure for explaining the sticking phenomenon of the pressure sensor. After the pressure measurement of the external space 1000 of the pressure sensor 1 is completed, when the external space 1000 is released to the atmospheric pressure, the flexible portion 151 is largely bent to the second substrate 20 side by the pressure. As a result, as shown in FIG. 4A, the flexible portion 151 is bent to a state in which the stopper 155 is sandwiched between the flexible portion 151 and the electrode 255. Although FIG. 4A shows an example in which the flexible portion 151 does not sandwich the stopper 155 with the surface of the second substrate 20, the flexible portion 151 and the second substrate 20 are shown. In some cases, the flexible portion 151 may further bend until the stopper 155 is sandwiched therebetween.

  Thereafter, when the next pressure measurement is started, the external space 1000 becomes a reduced pressure environment. At that time, if the flexible portion 151 returns to the state shown in FIG. 1 again, there is no problem in the measurement. On the other hand, as shown in FIG. 4B, the phenomenon that the stopper 151 and the electrode 255 (or the stopper 151 and the second substrate 20) do not separate while adhering to each other even though the external space 1000 has a reduced pressure environment. That is, the sticking phenomenon may occur. In such a state, even if the pressure in the external space 1000 changes, the amount of deflection of the flexible portion 151 can not follow the pressure change, and the pressure can not be measured.

  In general, silicon oxide is often used for the stopper 155, but the inventor of the present application has suggested that the stopper 155 and the electrode 255 be made of a metal having a predetermined hardness in order to eliminate the cause of the sticking phenomenon. It was found that it was desirable to form. Then, it was confirmed that the sticking phenomenon can be effectively suppressed when the stopper 155 is a metal material having a Vickers hardness of 0.5 GPa or more, preferably 1.0 GPa or more.

  As part of the cause of the sticking phenomenon, it is considered that the stopper 155 and the electrode 255 are coupled by electrostatic attraction, coupled by an intermolecular force, or the stopper 155 bites into the electrode 255.

  As described above, by forming the stopper 155 and the electrode 255 of metal respectively, charging can be prevented and coupling by electrostatic attraction can be suppressed. Further, by forming the stopper 155 and the electrode 255 of a hard material, they are less likely to be deformed, so that the unevenness of each surface is crushed and the contact area of the contact surface is increased. Can be suppressed. If the increase in the adhesion area is suppressed, the intermolecular force weakens. As a result, the sticking phenomenon is suppressed.

[Method of Manufacturing Pressure Sensor 1]
The pressure sensor 1 is formed by bonding the first substrate 10 and the second substrate 20. Each of the first substrate 10 and the second substrate 20 is bonded after undergoing a predetermined manufacturing process described below.

[Manufacturing Process for First Substrate 10]
FIG. 5 is a schematic view of a sectional structure for illustrating the method of manufacturing the first substrate of the pressure sensor according to the first embodiment of the present invention. First, the first substrate 10 shown in FIG. 5A is prepared. The first substrate 10 is an SOI substrate provided with an active layer 15 of silicon and a support layer 17 and further provided with a BOX layer 13 of silicon oxide sandwiched therebetween. At least the active layer 15 has conductivity.

  A part of the active layer 15 is etched to form a cavity 1501 (FIG. 5 (b)). At this time, the active layer 15 is etched so that a film having a predetermined thickness remains so as not to expose the BOX layer 13. For example, a silicon oxide film (thermal oxide film or the like) formed on the surface of the active layer 15 is subjected to a photolithography step and an etching step, and a portion corresponding to the cavity 1501 is opened. The active layer 15 may be etched by wet etching. The etching time is determined based on the etching amount obtained from the film thickness to be left and the etching rate of the active layer 15.

  The active layer 15 remaining in the cavity 1501 is a portion where a portion thereof becomes the flexible portion 151. Therefore, the film thickness to be left is appropriately set in accordance with the use environment of the pressure sensor 1. For example, when the pressure fluctuation in the measurement environment (the external space 1000) is small, the flexible portion 151 needs to be bent by a small pressure fluctuation, so that the film to be left is set to be thin. Conversely, when the pressure fluctuation in the measurement environment is large, the film to be left is set to be thick.

  For example, when the diameter of the flexible portion 151 is about 7.6 mm, the film thickness of the flexible portion 151 and the cavity depth of the active layer 15 (the surface of the flexible portion 151) according to the full scale of the pressure sensor 1 And the distance from the surface of the second substrate 20). These parameters are set, for example, as follows.

  When the full scale is 133 Pa (1 Torr), the film thickness of the active layer 15 is set to 31.5 μm, the film thickness of the flexible portion 151 is set to 21.5 μm, and the cavity depth is 10 μm. . When the full scale is 1330 Pa (10 Torr), the film thickness of the active layer 15 is set to 59 μm, and the film thickness of the flexible portion 151 is set to 49 μm and the cavity depth is 10 μm. When the full scale is 13300 Pa (100 Torr), the thickness of the active layer 15 is set to 107 μm, and the thickness of the flexible portion 151 is set to 90 μm and the cavity depth is set to 17 μm. When the full scale is 133000 Pa (1000 Torr), the film thickness of the active layer 15 is set to 219 μm, the film thickness of the flexible portion 151 is set to 202 μm, and the cavity depth is set to 17 μm.

  Next, the conductive layer 1505 is formed on the active layer 15 (FIG. 5C). The conductive layer 1505 is a metal having a Vickers hardness of 0.5 GPa or more formed by sputtering, evaporation or the like, and is, for example, Cr. Thereafter, a stopper 155 is formed in the cavity 1501 through a photolithography process and an etching process (FIG. 5D). Therefore, the film thickness of the conductive layer 1505 defines the height of the stopper 155, and is set to, for example, 1 to 5 μm. The stopper 155 may be formed using a conductive layer grown by a plating process. Specifically, a seed layer is formed by sputtering, a photolithography process using a negative resist, an electrolytic plating process for growing a plating layer (conductive layer) from an exposed seed layer, a resist peeling process, and an unnecessary seed layer are removed. After the process, the stopper 155 is formed.

[Manufacturing process for the second substrate 20]
FIG. 6 is a schematic view of a cross-sectional structure for illustrating the method of manufacturing the second substrate of the pressure sensor according to the first embodiment of the present invention. As shown in FIG. 6A, through electrodes 213 and 215 made of a conductive material (for example, tungsten or the like) are formed in the second substrate 20. The through electrodes 213 and 215 are formed by forming through holes in a glass substrate and embedding a conductive material in the through holes.

  Next, the electrode 253 connected to the through electrode 213 and the electrode 255 connected to the through electrode 215 are formed (FIG. 6B). The electrodes 253 and 255 are formed, for example, by sputtering, vapor deposition or the like of a laminated structure of Au in contact with the through electrode and Cr formed on Au, and then formed through a photolithography process and an etching process. As described above, Cr is an example of a metal having a Vickers hardness of 0.5 GPa or more. As described in the method for forming the stopper 155 described above, these electrodes may also be formed using the conductive layer grown in the plating process. In addition, the getter material 260 is formed.

[Bonding of First Substrate 10 and Second Substrate 20]
The first substrate 10 and the second substrate 20 thus formed are joined with the stopper 155 of the first substrate 10 and the electrode 255 of the second substrate 20 facing each other in a vacuum atmosphere. Since the first substrate 10 is silicon and the second substrate 20 is glass, for example, anodic bonding is used for this bonding. The conductive portion 155 and the electrode 255 are in contact with each other by this bonding.

[Manufacturing process of pressure sensor 1 after bonding of first substrate 10 and second substrate 20]
FIG. 7 is a cross-sectional view for explaining the method for manufacturing the pressure sensor 1 after the first substrate 10 and the second substrate 20 according to the first embodiment of the present invention are bonded. FIG. 7A shows the pressure sensor 1 after the first substrate 10 and the second substrate 20 are bonded. The electrode 253 is in contact with the active layer 15 to conduct electricity. The electrode 255 and the stopper 155 are disposed to face each other. The cavity 1501 is covered by the second substrate 20 to form an internal space 110.

  Next, the electrodes 233 and 235 are formed on the outer surface side (the opposite side to the internal space 110) of the second substrate 20 (FIG. 7B). The electrodes 233 and 235 are electrode pads for solder, and are formed as a laminated structure of, for example, Cu, Ti, Ni, Au or the like. These electrodes may also be formed by vapor deposition or etching and etching as in the case of the stopper 155, the electrodes 253, 255, etc. described above, or may be formed using a conductive layer grown by a plating process. The electrode 233 is connected to the through electrode 213. The electrode 235 is connected to the through electrode 215. The electrode 233 and the through electrode 213 are not limited to direct connection, and may be electrically connected via another metal wire. The same applies to the relationship between the electrode 235 and the through electrode 235.

  Next, the support layer 17 is etched and the BOX layer 13 is etched to expose the active layer 15, thereby forming the flexible portion 151 (FIG. 6C). For example, when etching is performed using photolithography, the support layer 17 is etched using the BOX layer 13 as an etching stopper, and then the BOX layer 13 is etched using the active layer 15 as an etching stopper. The etching may be dry etching or wet etching. The surface of the flexible portion 151 exposed in this manner is exposed to the external space 1000.

  Although the pressure sensor 1 described above is described as one sensor in the drawing, in an actual manufacturing process, a plurality of pressure sensors 1 are simultaneously formed on one substrate. Therefore, dicing is performed to separate each pressure sensor 1. In addition, about various conditions, such as the material of each structure in the manufacturing method mentioned above, an etching method, etc., it is an example and can be set to various conditions. The above is the description of the method of manufacturing the pressure sensor 1.

[Pressure measuring device]
Subsequently, a pressure measuring device 100 that measures the pressure in the external space 1000 using the pressure sensor 1 will be described with reference to FIG.

  FIG. 8 is a block diagram showing the configuration of a pressure measurement device using a pressure sensor according to the first embodiment of the present invention. The pressure measuring device 100 is a device that measures the pressure in the external space 1000, and includes a pressure sensor 1 and a control unit 2. The control unit 2 supplies a signal for measurement to the electrodes 233 and 235 of the pressure sensor 1 to measure the volume, performs a predetermined calculation on the measurement result of the volume, and calculates the pressure in the external space 1000 Output as a pressure measurement value.

  As described above, the stopper 155 is a conductive metal. Therefore, when the stopper 155 contacts the electrode 255 and the stopper 155 is sandwiched between the flexible portion 151 and the electrode 255, a short circuit occurs between the electrodes 233 and 235. Therefore, the control unit 2 stops the current supply between the electrodes 233 and 235 when the pressure sensor 1 is in such a condition. In the pressure sensor 1, the short circuit between the electrodes 233 and 235 may be detected as the case where the resistance between the electrodes 233 and 235 becomes lower than a predetermined value.

  As described above, in the pressure sensor 1 in the present embodiment, hard metal is disposed at least on the contact surface of the stopper 155 and the electrode 255. Therefore, in the pressure sensor 1, the sticking phenomenon is less likely to occur. By forming the stopper 155 of a metal having a Vickers hardness of 0.5 GPa or more, preferably 1.0 GPa or more, the sticking phenomenon can be significantly suppressed.

Second Embodiment
In the second embodiment, a pressure sensor 1A in which a stopper is disposed on the second substrate 20 side will be described.

  FIG. 9 is a schematic view of a cross-sectional structure for describing the structure of a pressure sensor according to a second embodiment of the present invention. The stopper 155A is disposed on the electrode 255A disposed on the second substrate 20. In addition, the stopper 155A may be further disposed in a region other than the electrode 255A.

  The stopper 155A is formed of a metal having a Vickers hardness of 0.5 GPa or more, preferably 1.0 GPa or more, as in the first embodiment. On the other hand, unlike the first embodiment, the electrode 255 is not a metal which is in direct contact with the flexible portion 151A, and is necessarily a metal having a Vickers hardness of 0.5 GPa or more, preferably 1.0 GPa or more. It does not have to be formed.

  As described above, even if the stopper 155A is disposed not on the flexible portion 151 whose deflection amount changes due to pressure change, but also on the side of the second substrate 20 which is also fixed due to pressure change, The occurrence of the phenomenon can be suppressed.

Third Embodiment
In the third embodiment, the first and second embodiments will be summarized, and a pressure sensor 1B in which stoppers are provided on both the first substrate 10 side and the second substrate 20 side will be described.

  FIG. 10 is a schematic view of a cross-sectional structure for describing the structure of a pressure sensor according to a third embodiment of the present invention. A stopper 155B1 is disposed on the flexible portion 151B on the first substrate 10 side. Also on the second substrate 20 side, the stopper 155B2 is disposed on the electrode 255B. The stopper 155B2 may be further disposed in a region other than the electrode 255B.

  The stoppers 155B1 and 155B2 are both formed of a metal having a Vickers hardness of 0.5 GPa or more, preferably 1.0 GPa or more. The positions of the stoppers 155B1 and 155B2 are determined such that the stopper 155B1 and the stopper 155B2 disposed to face the contact come into contact with each other when the flexible portion 151B is largely bent by a predetermined amount or more. .

  As described above, when the stoppers are disposed on both the first substrate 10 side and the second substrate 20 side, the occurrence of the sticking phenomenon can be further suppressed by contacting the stoppers formed of hard metal with each other. it can.

Fourth Embodiment
In the fourth embodiment, a pressure sensor 1C in which the positional relationship between the stoppers disposed in the flexible portion 151 is different from that in the first embodiment will be described.

  FIG. 11 is a plan view of a first substrate of a pressure sensor according to a fourth embodiment of the present invention as viewed from the second substrate side. In the first embodiment, as shown in FIG. 2, the stoppers 155 are arranged along a plurality of concentric circles of the circle of the flexible portion 151, and the stoppers 155 are arranged radially from the stopper 155 X arranged at the circle center. It had been. On the other hand, in the pressure sensor 1C, as shown in FIG. 11, the stoppers 155C are arranged in a grid shape in the flexible portion 151C. In FIG. 11, the stoppers 155C are arranged at equal intervals in both the X direction (horizontal direction in the drawing) and the Y direction (vertical direction in the drawing), but one direction is closer to the stopper than the other direction. It may be wide.

Fifth Embodiment
In the fifth embodiment, a pressure sensor 1D in which the positional relationship between the stoppers disposed in the flexible portion 151 is different from that in the first embodiment will be described.

  FIG. 12 is a plan view of a first substrate of a pressure sensor according to a fifth embodiment of the present invention as viewed from the second substrate side. The stoppers 155D are distributed in a distributed manner with a bias in the area SA of the flexible portion 151D. That is, the stopper 155D is disposed such that the center of the distribution of the stopper 155D and the center of gravity of the flexible portion 151D (in this example, the center of the circle) are at different positions. In this example, the density of the stopper 155D is high in the first area HA1 and low in the second area HA2. Therefore, the center of distribution is shifted to the area HA1 side from the center of gravity (center of circle) of the flexible portion 151D1. The center of the distribution may be, for example, a median value of X coordinates and a median value of Y coordinates in the XY coordinate system.

  As described above, by arranging the stopper 155D in the flexible portion 151D so as to have a bias, non-uniform stress or the like is generated in the flexible portion 151D. If this non-uniform stress is generated, even if the flexible portion 151D and the electrode 255 sandwich the stopper 155D, the non-uniform force, that is, the locally large force is likely to be applied to the flexible portion 151D. Therefore, the stopper 155D and the electrode 255 can be easily separated. Therefore, the occurrence of the sticking phenomenon is suppressed.

Sixth Embodiment
In the sixth embodiment, a pressure sensor 1E in which the size of the stopper (in this example, the area in contact with the flexible portion, hereinafter referred to as the installation area) is different will be described.

  FIG. 13 is a plan view of a first substrate of a pressure sensor according to a sixth embodiment of the present invention as viewed from the second substrate side. As shown in FIG. 13, the installation areas of the stopper 155 </ b> EX disposed at the center of the flexible part 151 </ b> E and the stopper 155 </ b> EE disposed at the periphery of the flexible part 151 </ b> E are different. In this example, the installation area is larger as it is disposed in the peripheral portion. When the flexible portion 151E bends, the displacement amount is maximum at the central portion, and the displacement amount is small at the peripheral portion. Therefore, in other words, the shape of the stopper in this example differs depending on the position, and the smaller the displacement amount (the peripheral portion), the larger the installation area when the flexible portion 151E bends.

  Moreover, in this example, the shape of the stopper other than the center is a substantially rectangular parallelepiped shape. With such a shape, when the flexible portion 151E is bent and the stopper contacts the electrode 255, among the sides of the stopper, the side closer to the center of the flexible portion 151E is likely to be in line contact Become.

  When the shape of the stopper is a circle, point contact is made on the side close to the center of the flexible portion 151E. In the case of point contact, since a force due to an impact at the time of contact is concentrated, a hard material is required to an extent that breakage of the stopper is prevented. On the other hand, by making line contact as in this example, the force due to impact can be dispersed and transmitted to the stopper in a weakened state.

Seventh Embodiment
In 7th Embodiment, the pressure sensor 1F which changed the shape of the stopper of the structure of 6th Embodiment into circular arc shape is demonstrated.

  FIG. 14 is a plan view of a first substrate of a pressure sensor according to a seventh embodiment of the present invention as viewed from the second substrate side. As shown in FIG. 14, the stopper 155FE has a shape along an arc concentric with the circle of the flexible portion 151F. Therefore, when the flexible portion 151F is bent and the stopper comes in contact with the electrode 255, the range of linear contact is further increased as compared with the sixth embodiment. Therefore, the force by the impact at the time of contact can be dispersed more.

Eighth Embodiment
In the eighth embodiment, an example of the sectional shape of the stopper will be described.

  FIG. 15 is a schematic view of a sectional structure for illustrating another example of the sectional shape of the stopper of the pressure sensor according to the eighth embodiment of the present invention. First, in each of the embodiments described above, as shown in FIG. 15A, the cross-sectional shape of the stopper 155 is rectangular. That is, the stopper 155 of the first embodiment has a cylindrical shape.

  In the case of this structure, the upper surface of the stopper 155X contacts the electrode 255 due to the bending of the flexible portion 151 (dotted line portion, hereinafter the same in this embodiment) for the stopper 155X at the center of the flexible portion 151. On the other hand, the other stoppers 155 contact the electrode 255 from the corner C on the stopper 155X side. As described in the sixth and seventh embodiments, in the corner portion C, since the force due to the impact at the time of contact is concentrated and transmitted, it is easily broken. Since the stopper is formed of a hard material and is formed of a metal that is not a brittle material but a ductile material, although the structure is not easily broken, it is desirable to suppress the possibility of breakage as much as possible.

  A structure in which the possibility of breakage is suppressed will be described with reference to FIGS. 15 (b) and 15 (c). In the structure shown in FIG. 15 (b), a stopper 155G in which a portion corresponding to the corner C is chamfered is disposed on the flexible portion 151G. By chamfering in this manner, breakage of the stopper 155G can be suppressed.

  In addition, in FIG.15 (b), although not only the center side but the corner | angular_part on the outer peripheral side is chamfered, it may not necessarily be chamfered about the outer peripheral side. In addition, the center stopper 155GX may not be chamfered.

  In the structure shown in FIG. 15C, the portion corresponding to the corner portion C has two steps of corner portions C1 and C2, and the stopper 155H formed to have two regions having different heights is a flexible portion It is arranged at 151H. When the flexible portion 155H is bent and the stopper 155H contacts the electrode 255, the two-step corner C1, C2 may be formed to contact the electrode 255 almost simultaneously. As described above, by providing the multi-step corner portions C1 and C2 having different heights, the force due to impact can be dispersed by these, and breakage of the stopper 155H can be suppressed. In addition, you may make it have the corner | angular part of not only 2 steps but multistep more. On the other hand, the stopper 155HX disposed at the center of the flexible portion 151H may not have two steps of corner portions.

<Other Embodiments>
In each of the above embodiments, the planar shape of the stopper (the shape of the portion where the stopper and the flexible portion are in contact) has been described as an example of a circle, a rectangle, and an arc, but it may be another shape. For example, the shape may be an ellipse, a polygon such as a triangle, a square, a trapezoid, a rhombus, or any shape as long as it is a figure surrounded by a curve and a straight line.

  The stopper may have not only a columnar shape such as a cylinder or a prism but also a conical shape such as a cone or a pyramid. In the case of the conical shape, the contact area between the stopper and the electrode can be reduced, and the sticking phenomenon can be further suppressed.

  The flexible portion 151 has a circular shape, but may have an oval shape or a polygonal shape such as a square or a rectangle. Also, the cavity 1501 of the first substrate 10 (the active layer 15) forming the internal space 110 is not limited to a square, and may be a polygon such as a rectangle, a circle, or an ellipse. Regardless of the shape, various arrangements of the stoppers described above can be applied. By lowering the symmetry of the shape of the flexible portion, the bending of the flexible portion may be made non-uniform to suppress the occurrence of the sticking phenomenon. It is desirable that the electrode 255 also have a shape corresponding to the shape of the flexible portion (a similar shape of the shape of the flexible portion), but may have a different shape (a shape other than the similar shape). However, since the area of the electrode 255 affects the capacitance value for calculating the pressure, it is necessary to calculate the area to determine the shape. Even if the shape is different, the versatility as a pressure sensor can be provided by setting the capacitance value to be the same. For example, when replacing with a pressure sensor having electrodes of different shapes, it is not necessary to change calculation parameters (parameters for calculating pressure) of a measuring device or the like to which the pressure sensor is connected. In addition, although the shape of the electrode can be changed, it is desirable to secure a sufficient area value, and the shape of the flexible portion is also preferably the same as the shape of the electrode. The shape of the cavity may be larger than that of the electrode portion.

  By setting the film of the stopper to a compressive stress equal to or more than a predetermined value, the flexible portion may be slackened and wrinkles may easily occur. In this manner, the bending of the flexible portion may be made uneven to suppress the occurrence of the sticking phenomenon.

  The second substrate 20 is a glass substrate, but may be a silicon substrate of high resistance (1 kΩcm or more). In this case, bonding with the first substrate 10 can be performed not by anodic bonding but by normal temperature bonding. In the case of normal temperature bonding, since there is no gas generation at the time of anodic bonding, the getter material 260 may not be used.

  About the surface which a stopper and an electrode (or flexible part) contact by bending of a flexible part among the surfaces of a stopper, processing which improves surface coarseness may be given.

  The pressure measurement device 100 may include a vibration device that applies ultrasonic vibration to the pressure sensor 1. This vibration can be used as an aid for canceling the sticking phenomenon. Ultrasonic vibration may be given before the start of measurement of pressure. The time during which the ultrasonic vibration is applied may be a predetermined time or may be a time until the short between the electrodes 233 and 235 is released.

  In addition, the pressure measuring device 100 includes a force applying unit that applies a force so as to deform the flexible portion by distorting the outer shape of the pressure sensor 1 and slightly distorting the first substrate 10. It is also good. This force can be used as an aid for releasing the sticking phenomenon. This force may be applied before the start of pressure measurement. The time for which the force is applied may be a predetermined time, or may be a time until the short between the electrodes 233 and 235 is released.

  In each of the above embodiments, the pressure sensor has been described, but the present invention can be applied to an acceleration sensor or the like. That is, the present invention is generally applied to a dynamic quantity sensor having a configuration in which a flexible part is flexed by the application of an external force, a capacity is formed by the flexible part and the fixed electrode, and the capacity is changed by the flexion amount be able to. Therefore, the pressure measuring device can also be applied as a mechanical quantity measuring device. In the case of an acceleration sensor or the like, since the sealed space such as the internal space 110 of the above embodiment may not be present, the entire periphery of the flexible part may not be fixed. Thus, the flexible portion may be like a cantilever.

  Each of the above-described embodiments may not be applied independently, but may be applied in duplicate.

DESCRIPTION OF SYMBOLS 1 ... Pressure sensor, 2 ... Control part 10 ... 1st board | substrate, 13 ... BOX layer, 15 ... Active layer, 17 ... Support layer, 20 ... 2nd board | substrate, 100 ... Pressure measurement apparatus, 110 ... Internal space, 151 ... Possible Flexible part, 155: stopper, 160: fixed part, 213, 215C: through electrode, 233, 235, 253, 255: electrode, 1000: external space, 1501: cavity, 1505: conductive layer

Claims (11)

A flexible portion that is conductive and that bends in response to an external force;
A fixed electrode disposed opposite to the flexible portion and forming a capacitance with the flexible portion;
A stopper disposed on the fixed electrode side of the flexible portion;
Equipped with
The mechanical quantity sensor characterized in that a metal having a Vickers hardness of 0.5 GPa or more is disposed on the surface of the stopper and the fixed electrode. A flexible portion that is conductive and that bends in response to an external force;
A fixed electrode disposed opposite to the flexible portion and forming a capacitance with the flexible portion;
A stopper disposed on the flexible portion side of the fixed electrode;
Equipped with
For the stopper, metal having a Vickers hardness of 0.5 GPa or more is disposed on the surface,
The stopper is further disposed on the fixed electrode side of the flexible portion,
The stopper disposed on the fixed electrode and the stopper disposed on the flexible portion contact each other when the flexible portion is bent toward the fixed electrode by a predetermined amount or more. Mechanical quantity sensor to be. The flexible portion is a circular membrane.
The stopper has a shape along a tangent at any position of the concentric circle of the circle,
The stopper is disposed at a position corresponding to a first displacement amount corresponding to a position where a first displacement amount is obtained when the flexible portion bends by a predetermined amount, and a second displacement amount corresponding to a position corresponding to a second displacement amount Including two stoppers,
The first displacement amount is smaller than the second displacement amount,
The dynamic quantity sensor according to claim 1, wherein the first stopper has a larger installation area than the second stopper. The flexible portion is a circular membrane.
The stopper is dynamic quantity sensor according to claim 1 or claim 2, characterized in that a circular arc shape concentric of said circle.   The dynamic quantity sensor according to claim 1 or 2, wherein the stopper has a chamfered surface at a position side where the displacement amount is maximum when the flexible portion bends. At least one of the stoppers has a plurality of regions having different heights, and the height is lower toward the position where the maximum displacement amount is obtained when the flexible portion is bent. The dynamic quantity sensor according to claim 1 or 2. The flexible portion is a membrane fixed in the periphery,
The dynamic quantity sensor according to claim 1 or 2, wherein the external force is generated by a pressure difference between both sides of the membrane.   The dynamic quantity sensor according to claim 1, wherein the stopper has a single-layer structure.   The mechanical quantity sensor according to claim 1, wherein the stopper has a structure of two or more layers.   The mechanical quantity sensor according to claim 1 or 2, wherein the plurality of stoppers are arranged such that the center of the distribution of the plurality of stoppers and the center of gravity of the flexible portion are at different positions. . A mechanical quantity sensor according to any one of claims 1 to 10 ;
A control unit configured to control a current flowing between the flexible portion and the fixed electrode via the stopper in a state in which the flexible portion and the fixed electrode sandwich the stopper;
The mechanical-quantity measuring device characterized by including.

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