Pressure sensor element and pressure sensor

Abstract

To provide a pressure sensor element with which the zero-point shift of sensor output brought about by substances deposited on diaphragm surfaces is reduced without sacrificing high responsiveness to pressure changes, and a pressure sensor that uses this pressure sensor element.MEANS FOR SOLVING THE PROBLEM: Provided are a pressure sensor element 1A comprising a diaphragm 2 having a region that is deformed by a difference between pressure on a first face 2aa and pressure on a second face 2ab, a protective film member 10A covering at least a portion of the first face 2aa of the diaphragm 2, and a sensor unit 4 for electrically detecting the deformation of the diaphragm 2 and disposed to the second face 2ab of the diaphragm 2, and a pressure sensor 100A provided with the pressure sensor element 1A.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a pressure sensor element and a pressure sensor using the same. [Background technology]

[0002] Pressure sensor elements with diaphragms and pressure sensors using such elements have been widely used as sensors for measuring fluid pressure. These pressure sensor elements and pressure sensors using such elements are configured to capture pressure changes in the fluid being measured (hereinafter referred to as the "measurement fluid") in the form of mechanical displacement, such as deformation of the diaphragm, detect this mechanical displacement as an electrical signal such as a voltage, and then measure the pressure of the measurement fluid from this electrical signal. For example, capacitance-type pressure sensor elements and pressure sensors using such elements are configured to detect diaphragm deformation as a change in capacitance between a pair of electrodes and measure the pressure of the measurement fluid based on this change in capacitance. Here, the diaphragm is disposed facing two spaces that are isolated from each other and do not communicate with each other, and the deformation is caused by the pressure difference generated when the measurement fluid flows in or out of one of the two spaces.

[0003] In the pressure sensor element and pressure sensor using the pressure sensor element, the pressure-receiving surface of the diaphragm, which receives the pressure of the fluid to be measured, comes into contact with the fluid. Therefore, when the pressure sensor element and pressure sensor using the pressure sensor element are used, for example, in a film-forming or etching process in a semiconductor device manufacturing system, a film-forming substance contained in the fluid to be measured adheres to the pressure-receiving surface of the diaphragm. The film-forming substance forms a film through a continuous chemical reaction and adheres to the pressure-receiving surface of the diaphragm with relatively strong force. In this film-forming process involving chemical reactions, forces acting between molecules or crystal lattices—known as internal film stress—are generated. This internal stress acts with great force on the adhered diaphragm, deforming it. Diaphragm deformation due to this internal stress shifts the zero point of the sensor output, resulting in problems such as reduced measurement accuracy. Therefore, technologies to solve this problem have been proposed.

[0004] An example of such a technique is the prior art described in Patent Document 1. To solve the above problem, this prior art is characterized in that a baffle is disposed in the upstream area before the fluid to be measured reaches the pressure-receiving surface of the diaphragm, and the flow of the fluid to be measured passing through the path within this baffle is made a molecular flow by, for example, making the representative length of the path shorter than the mean free path of the fluid molecules.

[0005] Another example of the above technology is the prior art described in Patent Document 2. To solve the above problem, this prior art is characterized in that a table-shaped, inverted tapered, or square wave-shaped structure is erected on the pressure-receiving surface of the diaphragm, and the pressure-receiving surface is formed as an uneven surface.

[0006] Another example of the above-mentioned technology is the prior art described in Patent Document 3. In order to solve the above-mentioned problem, this prior art is characterized by forming the shape of the diaphragm so that the rigidity decreases continuously from the center toward the periphery. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-149946 [Patent Document 2] Japanese Patent Application Laid-Open No. 2009-524024 [Patent Document 3] Japanese Patent Application Laid-Open No. 2010-236949 Summary of the Invention [Problem to be solved by the invention]

[0008] The prior art described in Patent Document 1 above requires a baffle, which complicates the structure and increases the number of parts and assembly steps, resulting in problems (issues) such as increased manufacturing costs. Additionally, the baffle increases the flow resistance of the fluid to be measured (deteriorating conductance), resulting in poor responsiveness to pressure fluctuations. The problem of poor responsiveness is particularly important in atomic layer deposition (ALD), which requires high responsiveness.

[0009] Furthermore, in the prior art described in Patent Documents 2 and 3, the diaphragm structure becomes complicated, which leads to problems such as an increase in manufacturing costs due to an increase in the number of processing steps and a decrease in yield. In addition, it is necessary to thoroughly verify whether the structure has high responsiveness.

[0010] The present invention was created in view of the above-mentioned problems, and its object is to provide a pressure sensor element and a pressure sensor using the same that reduce the zero point shift of the sensor output caused by material depositing on the diaphragm surface without sacrificing responsiveness to pressure fluctuations. [Means for solving the problem]

[0011] The pressure sensor element (1A, 1B, 1C) of the present invention for solving the above problem is characterized by comprising a diaphragm (2) having an area that deforms depending on the difference between the pressure applied to a first surface (2aa) and the pressure applied to a second surface (2ab), a protective film member (10A, 10B, 10C) that covers at least a portion of the first surface of the diaphragm, and a sensor unit (4) that is arranged on the second surface of the diaphragm and electrically detects the deformation of the diaphragm.

[0012] In the pressure sensor element, the protective film member may be removably attached to at least a portion of the first surface with a predetermined tensile adhesive strength.

[0013] Furthermore, in the pressure sensor element, the upper limit of the predetermined tensile adhesive strength is 100 N / m 2 It may be configured to be:

[0014] In the pressure sensor element, at least one of the protective film member and a member in contact therewith may be processed to adjust the contact area therebetween.

[0015] Furthermore, in the pressure sensor element, the upper limit of the thickness of the protective film member may be set to 0.34% of the thickness of the deformable region of the diaphragm.

[0016] In the pressure sensor element, the protective film member may be made of a material having at least the same heat resistance and corrosion resistance as the diaphragm.

[0017] Furthermore, in the pressure sensor element, the diaphragm and the protective film member may be made mainly of the same material, and the material may be sapphire, polycrystalline alumina, or a nickel-based alloy.

[0018] In addition, in the pressure sensor element, the diaphragm and the protective film member may be mainly composed of different materials, the diaphragm being mainly composed of one of sapphire, polycrystalline alumina, or a nickel-based alloy, and the protective film member being mainly composed of one of sapphire, a nickel-based alloy, or a fluororesin.

[0019] Furthermore, the pressure sensor element may further include a base having a third surface opposite to the second surface, and a pair of electrodes constituting the sensor portion may be arranged on the second surface and the third surface.

[0020] In addition, the pressure sensor of the present invention, which solves the above problem, is characterized by comprising the pressure sensor element, a casing that, together with the diaphragm, defines a space through which the fluid whose pressure is to be measured flows in and out, and a support member that supports the pressure sensor element on the casing.

[0021] In the above description, as an example, reference numerals in the drawings corresponding to components of the invention are given in parentheses. [Effects of the Invention]

[0022] According to the present invention, it is possible to provide a pressure sensor element and a pressure sensor using the same in which the zero point shift of the sensor output caused by material depositing on the diaphragm surface is reduced without sacrificing responsiveness to pressure fluctuations. [Brief explanation of the drawings]

[0023] [Figure 1] FIG. 1 is a vertical cross-sectional view of a pressure sensor element according to an embodiment of the present invention. [Figure 2] FIG. 2 is an enlarged cross-sectional view of a portion X in FIG. [Figure 3] FIG. 3 is an enlarged cross-sectional view of a portion X in FIG. [Figure 4] FIG. 4 is a vertical cross-sectional view of a pressure sensor element according to another embodiment of the present invention. [Figure 5] FIG. 5 is a vertical cross-sectional view of a pressure sensor element according to another embodiment of the present invention. [Figure 6] FIG. 6 is a longitudinal sectional view of a capacitance type pressure sensor including a pressure sensor element according to an embodiment of the present invention. [Figure 7] FIG. 7 is a vertical cross-sectional view showing an operation mode of the pressure sensor element according to the embodiment of the present invention. [Figure 8] FIG. 8 is a vertical cross-sectional view showing an operation mode of the pressure sensor element according to the embodiment of the present invention. [Figure 9] FIG. 9 is a vertical cross-sectional view of a pressure sensor element according to another embodiment of the present invention. [Figure 10] FIG. 10 is a vertical cross-sectional view of a pressure sensor element according to another embodiment of the present invention. [Figure 11] FIG. 11 is a vertical cross-sectional view of a pressure sensor element according to another embodiment of the present invention. [Figure 12] FIG. 12 is a vertical cross-sectional view of a pressure sensor element according to another embodiment of the present invention. [Figure 13] FIG. 13 is a vertical cross-sectional view of a pressure sensor element according to another embodiment of the present invention. [Figure 14] FIG. 14 is a vertical cross-sectional view of a pressure sensor element according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0024] First Embodiment A capacitance-type pressure sensor element 1A, which is one of the preferred embodiments of the present invention, and a capacitance-type pressure sensor 100A using the same will be described as a first embodiment with reference to Figures 1 to 7. Here, the front-to-rear direction, the up-down direction, and the left-to-right direction in the description are defined as the depth direction, the up-down direction, and the left-to-right direction, respectively, relative to the paper surface of the pressure sensor element 1A shown in Figure 1 and the pressure sensor 100A shown in Figure 4. Furthermore, each figure is a conceptual diagram, and the contents shown do not necessarily match the actual pressure sensor element and pressure sensor.

[0025] [Configuration of pressure sensor element 1A] First, the configuration of a pressure sensor element 1A that is incorporated into a pressure sensor 100A will be described with reference to FIG. 1, which is a vertical cross-sectional view.

[0026] The pressure sensor element 1A is an element that detects pressure changes in the measurement fluid L as mechanical displacement and further detects this mechanical displacement as an electrical signal (e.g., a voltage signal). The pressure sensor element 1A has a thin plate shape, for example, approximately 1 cm square in plan view, and as shown in FIG. 1, is mainly composed of a diaphragm 2, a base 3 that is connected to the diaphragm 2 to form a capacitance chamber C1, a sensor electrode section 4 (this sensor electrode section 4 corresponds to the "sensor section" in the claims) housed inside the capacitance chamber C1, and contact pads 5 that are electrically connected to electrode lead pins 41, which are components of a pressure sensor 100A described later. Furthermore, a protective film member 10A is provided to cover all or part of the surface of the diaphragm 2, more specifically, the surface facing a space C2 through which the measurement fluid L flows by communicating with an introduction section 20V described later.

[0027] [Diaphragm 2] The diaphragm 2 forms a boundary wall separating the volume chamber C1 maintained at a vacuum pressure from the space C2 through which the fluid to be measured L flows in and out, and is a mechanical element that deforms in response to pressure changes in the fluid to be measured L, and is made of a material whose main component is, for example, sapphire, which is a single crystal of aluminum oxide, polycrystalline alumina, or a nickel-based alloy. The diaphragm 2 is composed of a sensing portion 2a disposed approximately in the center thereof that deforms in response to pressure changes in the fluid to be measured L, and a fixed portion 2b that connects to and supports the outer edge of the sensing portion 2a.

[0028] The sensing unit 2a is thin and disk-shaped, and is disposed so that its axis coincides with the axis of the pressure sensor element 1A (this axis is coaxial with the axis of the pressure sensor 100A, which will be described later). The sensing unit 2a has a pressure-receiving surface 2aa (this pressure-receiving surface 2aa forms part of the "first surface" in the claims) that faces the space C2 and receives the pressure of the fluid L to be measured, and a measurement surface 2ab (this measurement surface 2ab forms part of the "second surface" in the claims) that is located on the back side of the pressure-receiving surface 2aa and defines the capacity chamber C1 together with the base 3. The pressure-receiving surface 2aa is, for example, circular in shape with an outer diameter D2aa, and is covered over substantially the entire area with a thin-film protective film, the details of which will be described later. A membrane member 10A is attached to the measurement surface 2ab. The measurement surface 2ab is, for example, circular with an outer diameter D2ab, and a sensor electrode unit 4 (more specifically, a movable electrode 4a, which will be described later) is attached approximately in the center. If the outer diameter D2aa of the pressure-receiving surface 2aa and the outer diameter D2ab of the measurement surface 2ab are different, the portion that bends under the pressure of the measurement fluid L will be the region formed by the smaller of these two outer diameters (in FIG. 1, D2aa > D2ab, so the region is formed as a cylindrical portion whose diameter is the inner diameter D2ab of the measurement surface 2ab and whose height is the thickness T2 of the diaphragm 2). Hereinafter, this region may be referred to as the "deformation region 2aα."

[0029] The fixed portion 2b has substantially horizontal upper and lower surfaces, and its outer wall forms the side wall of a square prism measuring 1 cm on each side in a plan view. The inner wall surface where the connection portion with the sensing portion 2a is formed is, for example, formed by a first cylindrical inner circumferential wall surface 2w1 having an inner diameter equal to the outer diameter D2aa of the pressure-receiving surface 2aa on the side connecting to the pressure-receiving surface 2aa, and a second cylindrical inner circumferential wall surface 2w2 having an inner diameter equal to the outer diameter D2ab of the measurement surface on the side connecting to the measurement surface 2ab. Here, the first cylindrical inner circumferential wall surface 2w1 forms a part of the wall portion defining the space C2, and the second cylindrical inner circumferential wall surface 2w2 forms a part of the wall portion defining the volume chamber C1. In a modified embodiment of the sensing portion 2a, the connection portion functions as a fixed end.

[0030] [Pedestal 3] The base 3 supports the diaphragm 2 and, as described above, together with the diaphragm 2 (more specifically, the measurement surface 2ab of the diaphragm 2 and the second cylindrical inner circumferential wall surface 2w2), defines the capacitance chamber C1 in which the sensor electrode portion 4 is housed, and is made of a thin plate member measuring 1 cm square in a plan view. The sensor electrode portion 4 (more specifically, the fixed electrode 4b, which will be described later) is affixed to the fixed surface 3a of the base 3 facing the capacitance chamber C1.

[0031] [Sensor electrode part 4] The sensor electrode unit 4 is an electric element that electrically detects the deformation of the diaphragm 2, and as described above, comprises a movable electrode 4a affixed to the measurement surface 2ab of the diaphragm 2 and a fixed electrode 4b affixed to the fixed surface 3a of the base 3. The movable electrode 4a and fixed electrode 4b form a capacitor with a predetermined capacitance.

[0032] [Contact Pad 5] The contact pad 5 is a portion electrically connected to the sensor electrode section 4, and is composed of a pair of contact pads 5a, 5b arranged on the surface opposite to the fixed surface 3a of the base 3. The pair of contact pads 5a, 5b are made of, for example, gold or platinum, and are electrically connected to the movable electrode 4a and the fixed electrode 4b arranged in the capacitance chamber C1, respectively, through predetermined wiring (not shown).

[0033] [Protective film member 10A] A protective film member 10A made of a thin metal material and having a generally circular shape in a plan view is attached to the surface of the sensing unit 2a facing the space C2, i.e., the pressure-receiving surface 2aa, so as to cover all or part of the surface. The outer peripheral edge of this protective film member 10A has a shape complementary to the first cylindrical inner peripheral wall surface 2w1, and its outer diameter D10A is set slightly smaller than the outer diameter D2aa of the pressure-receiving surface 2aa from the perspective of assembly. Furthermore, from the perspective of reliability, it is desirable for the protective film member 10A to have heat resistance and corrosion resistance equivalent to those of the diaphragm 2. In this embodiment, the protective film member 10A is formed mainly from the same material as the diaphragm 2, i.e., one of sapphire, polycrystalline alumina, and a nickel-based alloy.

[0034] It is desirable that the protective film member 10A adhere to the diaphragm 2 with a predetermined force (hereinafter, sometimes referred to as "adhesion force f"). The magnitude of this adhesion force f should be set based on the balance between the force acting on the protective film member 10A, specifically, the force resulting from the internal stress of the film generated from the film-forming substance, and other forces, for example, the force acting when the fluid L to be measured flows in and out of the space C1. For example, the protective film member 10A is set so that it peels off from the diaphragm 2 when the former force acts on it, but does not peel off from the diaphragm 2 when the latter force acts on it. The desirable adhesion force f set in this way is, for example, set so that its upper limit is 100 N / m in tensile adhesive strength. 2 Furthermore, when the pressure sensor element 1A and the pressure sensor 100A incorporating the same are installed with the protective film member 10A positioned below the diaphragm 2, the lower limit is set to, for example, a force equivalent to the weight of the protective film member 10A so that the protective film member 10A does not peel off due to its own weight.

[0035] The relationship between the internal stress of the film acting on the protective film member 10A and the adhesive force f can be considered as follows. That is, the internal stress of the film (e.g., tensile stress or compressive stress) acts on the surface of the protective film member 10A on which the film Sa is formed, generating a bending moment M1 that pulls both ends together or apart. On the other hand, when a load caused by the adhesive force f (the load applied when the protective film member 10A peels off from the diaphragm 2) acts on the protective film member 10A, a bending moment M2 is generated. If the adhesive force f is set so that the bending moment M2 is smaller than the bending moment M1 (in other words, so that the load caused by the adhesive force f is smaller than the load that generates the bending moment M1), when the bending moment M1 caused by the internal stress of the film is generated in the protective film member 10A, the protective film member 10A will peel off from the diaphragm 2. Here, the bending moment M1 caused by the internal stress of the membrane can be approximately determined from the relational equation σ = M / Z (σ: maximum stress (internal stress of the membrane) of the protective membrane member 10A, Z: section modulus of the protective membrane member 10A) when the deflection of the protective membrane member 10A is approximated as the deflection of a beam (item 1). Furthermore, the load caused by the adhesive force f is correlated with the bending moment M2. In other words, the load caused by the adhesive force f and the bending moment M2 have a relationship in which one can be expressed as a function of the other (item 2). From these two items and the fact that the bending moment M2 is smaller than the bending moment M1, the relationship between the adhesive force f and the internal stress of the membrane (a relationship in which one can be expressed as a function of the other) can be approximately determined.

[0036] Here, when the protective film member 10A and the diaphragm 2 are mainly made of the same material, they adhere with a relatively strong force due to surface free energy. For this reason, when the contact area of ​​the two surfaces that come into contact, for example, in the pressure sensor element 1A shown in FIG. 1, is relatively large, and when both surfaces are smooth, the desired adhesive force f (for example, a tensile adhesive strength of 100 N / m 2In this case, the adhesive force f may be adjusted to a desired value by reducing the contact area between the pressure-receiving surface 2aa and the contact surface 10Aa. To achieve this adjustment, for example, the first to fourth processes described below may be performed in appropriate locations.

[0037] First processing for adjusting the contact area between the pressure-receiving surface 2aa and the contact surface 10Aa For example, at least one of the two contacting surfaces is processed to have a predetermined roughness (for example, an arithmetic mean roughness (Ra) of about several μm). This reduces the contact area compared to when the surfaces are in contact in a smooth state, and allows adjustment to reduce the adhesive force f (adhesion strength). This first processing is performed, for example, by machining. Figure 2 shows a conceptual diagram of when the surface of the contact surface 10Aa of the protective film member 10A has a predetermined roughness. Note that instead of processing the surface of the contact surface 10Aa to be rough, the pressure-receiving surface 2aa of the diaphragm 2 may also be processed to have a predetermined roughness.

[0038] Second processing for adjusting the contact area between the pressure-receiving surface 2aa and the contact surface 10Aa Alternatively, a second process may be performed to provide irregularities on the contact surface 10Aa of the protective film member 10A. For example, as shown in FIG. 3, these irregularities are formed by convex portions 10Ac and concave portions 10Ad formed on the contact surface 10Aa and having a substantially rectangular cross-sectional shape. The convex portions 10Ac and concave portions 10Ad are formed by, for example, applying the same material as the protective film member 10A to a portion of the contact surface 10Aa through microfabrication such as photolithography or film formation processing such as vapor deposition, and / or by cutting a portion of the contact surface 10Aa. The convex portions 10Ac formed by applying the same material as the protective film member 10A to a portion of the contact surface 10Aa through vapor deposition or the like function as an adhesive member for bonding the diaphragm 2 and the protective film member 10A together. The shapes of the convex portions 10Ac and the concave portions 10Ad (such as their longitudinal and transverse cross-sectional shapes and arrangement) are not limited to any particular shape as long as they reduce the contact area between the pressure-receiving surface 2aa of the diaphragm 2 and the contact surface 10Aa of the protective film member 10A. For example, the longitudinal cross-sectional shape may be a rectangle as shown in FIG. 3 , or may be an approximately triangular or semicircular shape. The transverse cross-sectional shape and arrangement may be a groove-like shape extending along a horizontal plane, or a columnar or conical protruding and recessed shape. Furthermore, when the convex portions 10Ac and the concave portions 10Ad are groove-like, multiple grooves extending linearly or curvedly may be arranged in parallel, in a lattice pattern, radially, or randomly. When the convex portions 10Ac and the concave portions 10Ad are columnar or conical protruding and recessed shapes, the multiple convex portions 10Ac and the concave portions 10Ad may be arranged at regular intervals to form a predetermined shape, or may be arranged randomly.

[0039] Although not shown, instead of or in addition to the irregularities provided on the contact surface 10Aa of the protective film member 10A, irregularities may be provided on the pressure-receiving surface 2aa of the diaphragm 2. These irregularities consist of convex portions 2c (not shown) and concave portions 2d (not shown) that may have the same or different shapes as the convex portions 10Ac and concave portions 10Ad. The convex portions 2c, formed by depositing the same material as the diaphragm 2 on a portion of the pressure-receiving surface 2aa by vapor deposition or the like, function as an adhesive for bonding the diaphragm 2 to the protective film member 10A, similar to the convex portions 10Ac. When providing irregularities (convex portions 2c and concave portions 2d, not shown) on the pressure-receiving surface 2aa, it is desirable to determine their shape taking into consideration their effect on deformation of the sensing unit 2a, i.e., the rigidity of the diaphragm 2. It is also desirable to provide them in a shape and position that prevents them from engaging with each other so as not to increase the contact area.

[0040] <c>Third processing for adjusting the contact area between the pressure-receiving surface 2aa and the contact surface 10Aa The protective film member 10A may be subjected to a third process, such as a press or other mechanical process, or the above-described micromachining and film-forming process, to form convex portions 10Ac' and concave portions 10Ad' in a longitudinal cross-sectional shape while maintaining a substantially constant film thickness, as shown in FIG. 4. This third process allows for easy adjustment of the contact area between the pressure-receiving surface 2aa and the contact surface 10Aa without reducing the strength of the protective film member 10A. The shapes of the convex portions 10Ac' and the concave portions 10Ad' (such as the longitudinal cross-sectional shape and cross-sectional shape, and their arrangement) are not limited to any particular shape as long as they reduce the contact area between the pressure-receiving surface 2aa of the diaphragm 2 and the contact surface 10Aa of the protective film member 10A. For example, the convex portions 10Ac' and the concave portions 10Ad' in the longitudinal cross-sectional shape shown in FIG. 4 may be groove-shaped extending along a horizontal plane, or the convex portions 10Ac' and the concave portions 10Ad' may be columnar or pyramidal. Furthermore, the longitudinal cross-sectional shape may be a rectangular shape, a substantially triangular shape, or a substantially semicircular shape in addition to a substantially trapezoidal shape. Furthermore, when the protrusions 10Ac' and the recesses 10Ad' are groove-shaped, a plurality of grooves extending linearly or curvedly may be arranged in parallel, in a lattice pattern, or radially, or may be randomly arranged. When the protrusions 10Ac' and the recesses 10Ad' are in the form of columnar or conical depressions, the plurality of protrusions 10Ac' and recesses 10Ad' may be arranged at regular intervals to form a predetermined shape, or may be randomly arranged.

[0041] <d>The fourth process for adjusting the contact area between the pressure-receiving surface 2aa and the contact surface 10Aa Furthermore, a fourth process may be performed on the diaphragm 2 to provide an abutment surface 2ba that comes into contact with the contact surface 10Aa instead of the pressure-receiving surface 2aa. In this case, the adhesive force f can be adjusted by adjusting the surface area of ​​the abutment surface 2ba. For example, the surface area of ​​the abutment surface 2ba is adjusted so that the contact area with the contact surface 10Aa is smaller than the contact area between the pressure-receiving surface 2aa and the contact surface 10Aa. This allows the adhesive force f to be adjusted to be lower. The abutment surface 2ba is formed on the fixed portion 2b of the diaphragm 2, as shown in FIG. 5, for example. Specifically, the first cylindrical inner peripheral wall surface 2w1 of the fixed portion 2b is machined into a stepped shape by cutting a portion thereof, and the abutment surface 2ba, which is a substantially horizontal surface, is formed on the upper surface of this stepped portion. The abutment surface 2ba has, for example, a circular ring shape in a plan view, and its outer periphery has a shape complementary to that of the outer periphery of the protective film member 10A. Furthermore, a step of height Tc is formed between the abutment surface 2ba and the pressure-receiving surface 2aa, and when the pressure-receiving surface 2aa and the contact surface 10Aa are in a static state (a state in which no pressure difference occurs between the pressure-receiving surface 2aa and the measurement surface 2ab of the diaphragm 2), they are separated by the height Tc and are not in contact with each other. Here, the inner peripheral edge of the abutment surface 2ba is formed so that its inner diameter dimension d2ba is larger than, for example, the outer dimension D2ab of the measurement surface 2ab. By providing an inner peripheral edge with such a shape, the abutment surface 2ba is formed outside the sensing unit 2a (deformation region 2aα). Also, the height Tc from the pressure-receiving surface 2aa is set to be equal to or smaller than the thickness T10A of the protective film member 10A, for example. Furthermore, an inverted truncated cone-shaped chamfer R is formed on the inner peripheral edge side wall of the abutment surface 2ba. By providing the abutment surface 2ba with such a shape, when the pressure of the measurement fluid L is applied, the protective film member 10A abuts on approximately the entire pressure-receiving surface 2aa (more specifically, the surface facing the space C2 in the sensing unit 2a (deformation region 2aα)) without making a lateral contact. As a result, the pressure of the fluid L to be measured is transmitted to the sensing section 2a (deformation area 2aα) in a desired form (e.g., uniformly distributed load) through the protective film member 10A, and the same level of measurement accuracy can be maintained as when the protective film member 10A is not present.

[0042] By carrying out the above processes, the contact area between the pressure-receiving surface 2aa and the contact surface 10Aa can be reduced, and the adhesive force f can be adjusted to a desired value. Note that the first to fourth processes for the above adjustments may be carried out as needed, and are not necessarily carried out in this embodiment. Furthermore, any one of the processes may be carried out, or they may be carried out in combination.

[0043] The thickness T10A of the protective film member 10A is set, for example, as follows: In this embodiment, where the diaphragm 2 and the protective film member 10A are primarily made of the same material, it is assumed that these two abutting members deform together. Therefore, the thickness of the protective film member 10A may affect the deformation of the diaphragm 2, in other words, the accuracy of pressure measurement (pressure sensitivity). In this embodiment, the thickness T10A of the protective film member 10A is set so that this effect is, for example, 1% or less. Specifically, in this embodiment, where the diaphragm 2 and the protective film member 10A are primarily made of the same material (materials with the same Young's Modulus), the thickness T10A is set so that the area moment of inertia I1 of the integrated diaphragm 2 and the protective film member 10A is 1.01 times or less the area moment of inertia I2 of the diaphragm 2 alone. In this case, the thickness T10A is 0.34% or less of the thickness T2 of the diaphragm 2.

[0044] [Configuration of pressure sensor 100A] Next, the configuration of a capacitance type pressure sensor 100A incorporating the pressure sensor element 1A will be described with reference to FIG. 6, which is a vertical cross section.

[0045] The pressure sensor 100A comprises a pressure sensor element 1A, a casing 20, a base plate 30 housed within the casing 20, a support diaphragm 40 joined to the base plate 30 and bridged across the casing 20, and an electrode lead portion 50 electrically connecting the inside and outside of the casing 20.

[0046] [Casing 20] The casing 20 forms the outer frame (housing) of the pressure sensor 100A, supports the pressure sensor element 1A via a base plate 30 and a support diaphragm 40 (described later), and defines an inlet 20V through which the measurement target fluid L flows in and out. The casing 20 is configured, for example, by stacking an upper housing 21, a lower housing 22, and a cover 23 in this order. The upper housing 21, the lower housing 22, and the cover 23 are made of, for example, Inconel, a corrosion-resistant metal, and opposing portions are joined by welding.

[0047] The upper housing 21 is a cylindrical portion formed of a large-diameter cylindrical portion 21a and a small-diameter cylindrical portion 21b, and these two portions are connected coaxially. The lower open end of the large-diameter cylindrical portion 21a is connected to the upper open end of the lower housing 22 via a support diaphragm 40. The inner circumferential wall of the small-diameter cylindrical portion 21b defines an inlet portion 20V into which the fluid to be measured L flows.

[0048] The lower housing 22 is a generally cylindrical portion interposed between the upper housing 21 and the cover 23. As described above, its upper open end is connected to the lower open end of the upper housing 21 via the support diaphragm 40, and its upper open end is connected to the cover 23. The lower housing 22, together with the cover 23, the support diaphragm 40, the base plate 30, and the pressure sensor element 1A, defines an independent reference vacuum chamber 20W within the casing 20. The reference vacuum chamber 20W is filled with a gas-absorbing substance known as a getter (not shown) to maintain a desired degree of vacuum. A stopper 22a protrudes from an appropriate position on the inner peripheral wall surface near the upper open end. The stopper 22a prevents the base plate 30 from moving excessively due to a sudden increase in pressure of the fluid L to be measured.

[0049] The cover 23 is made of a substantially disc-shaped plate, and an electrode lead insertion hole 23a is formed at a predetermined position of the cover 23. The electrode lead portion 50 is embedded in the electrode lead insertion hole 23a via a hermetic seal 60, thereby ensuring a predetermined sealing performance.

[0050] [Base plate 30] The base plate 30 is a portion that supports the pressure sensor element 1A and is composed of a first base plate 31 and a second base plate 32. The base plate 30 is supported so as to be bridged by the casing 20 via a support diaphragm 40, which will be described later.

[0051] The first base plate 31 and the second base plate 32 are made of, for example, sapphire, which is a single crystal of aluminum oxide. Both the first base plate 31 and the second base plate 32 are located away from the inner surface of the casing 20, with the former bonded to the upper surface of the support diaphragm 40 and the latter bonded to the lower surface of the support diaphragm 40. The first and second base plates 31, 32 are sufficiently thick compared to the thickness of the support diaphragm 40, which prevents the base plate 30 from warping due to thermal stress caused by the difference in thermal expansion coefficient between the base plate 31 and the support diaphragm 40.

[0052] The first base plate 31 and the second base plate 32 have introduction holes 31a and 32a opening at approximately their centers to connect the space C2, which faces the pressure-receiving surface 2aa of the diaphragm 2 of the pressure sensor element 1A, with the introduction section 20V into which the measurement target fluid L flows. The pressure sensor element 1A is bonded to the lower surface of the second base plate 32 via an aluminum oxide-based bonding material so that the introduction hole 32a and the space C2 communicate with each other. The bonding between the second base plate 32 and the pressure sensor element 1A can be performed by a well-known method, and a description thereof will be omitted.

[0053] [Support diaphragm 40] As described above, the support diaphragm 40 is a portion provided to bridge the base plate 30 through the casing 20, and is made of a thin Inconel plate. Its shape matches the outer peripheral shape of the casing 20, specifically, the outer peripheral shapes of the lower open end of the upper housing 21 and the upper open end of the lower housing 22. The support diaphragm 40 has the first base plate 31 joined to its upper surface and the second base plate 32 joined to its lower surface, and its outer peripheral portion (peripheral edge) is sandwiched between the lower open end of the upper housing 21 and the upper open end of the lower housing 22 and joined by welding or the like. In this embodiment, the thickness of the support diaphragm 40 is, for example, several tens of microns, which is sufficiently thinner than the first and second base plates 31 and 32. In addition, in the center of the support diaphragm 40, along with the introduction holes 31a and 32a, an introduction hole 40a is opened to connect the space C2 facing the pressure-receiving surface 2aa of the diaphragm 2 with the introduction section 20V into which the measured fluid L flows.

[0054] [Electrode lead part 50] The electrode lead portion 50 includes an electrode lead pin 51 and a metal shield 52. The center portion of the electrode lead pin 51 is embedded in the metal shield 52 by a hermetic seal 53 made of an insulating material such as glass, maintaining an airtight state between both ends of the electrode lead pin 51. One end of the electrode lead pin 51 is exposed to the outside of the casing 20, and is configured to transmit the output of the pressure sensor 100A to an external signal processing unit via wiring (not shown). As mentioned above, the hermetic seal 53 is also interposed between the shield 52 and the cover 23. Furthermore, conductive contact springs 55 and 56 are connected to the other end of the electrode lead pin 51.

[0055] The contact springs 55, 56 are provided to absorb displacement of the pressure sensor element 1A due to a sudden rise in pressure caused by the sudden inflow of the fluid to be measured L from the inlet portion 20V (more specifically, when the pressure rise causes the base plate 30, which is bridged to the casing 20 via the support diaphragm 40, to displace, and the pressure sensor element 1A supported thereby to displace), thereby preventing this displacement from affecting the measurement accuracy of the pressure sensor element 1A.

[0056] [Operational Mode of Pressure Sensor 100A] Next, an operation mode of the pressure sensor 100A incorporating the pressure sensor element 1A will be described. Note that in the following description, it is assumed that the pressure sensor 100A is a vacuum gauge attached to a predetermined location in an ALD film formation apparatus.

[0057] In the pressure sensor element 1A configured as described above and the pressure sensor 100A incorporating the same, a fluid L to be measured having a predetermined pressure flows into the inlet 20V of the pressure sensor 100A and then reaches the pressure-receiving surface 2aa of the diaphragm 2 through the space C2. At this time, a pressure difference occurs between the pressure-receiving surface 2aa and the measurement surface 2ab facing the volume chamber C1 where a vacuum pressure is maintained, causing the diaphragm 2 to deform. As the diaphragm 2 deforms, the movable electrode 4a disposed on the measurement surface 2ab displaces toward the fixed electrode 4b disposed on the fixed surface 3a of the base 3, shortening the distance between these two electrodes. As a result, the capacitance of the sensor electrode 4, which is composed of the movable electrode 4a and the fixed electrode 4b, changes. An electrical signal (e.g., a voltage signal) corresponding to this change in capacitance of the sensor electrode 4 is transmitted via the electrode lead 50 to a signal processor located outside the pressure sensor 100A. The signal processor then calculates (measures) the pressure of the fluid L using a known method.

[0058] Here, the measurement fluid L flowing in the ALD film formation apparatus contains a substance (hereinafter referred to as "film formation substance S") for forming a film consisting of a predetermined component on a substrate such as a wafer. As the measurement fluid L passes through the internal space of the piping and the chamber, this film formation substance S collides with the walls that define these internal spaces, and a part of it adheres to the wall surface. Therefore, the film formation substance S adheres to the surface of the diaphragm 2 that defines the space C2 through which the measurement fluid L flows in and out, i.e., the protective film member 10A attached to the pressure-receiving surface 2aa of the diaphragm 2 (more specifically, the contact surface 10Ab of the protective film member 10A facing the space C2), and accumulates over time.

[0059] As mentioned in the "Background Art" section at the beginning, the film-forming substance S attached to the protective film member 10A (contact surface 10Ab) forms a film Sa through a series of chemical reactions and adheres to the protective film member 10A (more specifically, the contact surface 10Ab) with relatively strong force. During this film-forming process accompanied by chemical reactions, forces acting between molecules or crystal lattices, known as internal film stress, are generated. This internal film stress acts with strong force on the adhered protective film member 10A through the contact surface 10Ab, deforming the protective film member 10A. Specifically, when the internal stress is a strong tensile stress, the reaction force acts to pull both ends of the protective film member 10A together, resulting in deformation of the protective film member 10A into a shape in which the peripheral edges are warped (hereinafter referred to as a "concave shape") (see Figure 7). When the internal stress is strong compressive stress, the reaction force acts to pull both ends of the protective film member 10A apart, resulting in the protective film member 10A being deformed into a shape with a raised center (hereinafter referred to as a "convex shape") (see Figure 8). Whether the internal stress is strong tensile stress or strong compressive stress depends on the components (constituent elements, etc.) of the film-forming material S and the position and amount where the film-forming material S is deposited.

[0060] In the pressure sensor element 1A according to the present invention, the diaphragm 2 and the protective film member 10A are bonded together through the pressure-receiving surface 2aa and the contact surface 10Aa by a predetermined adhesive force f (for example, 100 N / m 2 The protective film member 10A is attached with an adhesive force f) corresponding to the tensile adhesive strength below. This adhesive force f is smaller than the adhesion force between the film Sa formed from the film-forming substance S and the protective film member 10A, and as described above, is set so that the protective film member 10A will separate from the diaphragm 2 when the internal stress of the film Sa formed from the film-forming substance S acts on the protective film member 10A and deforms into a convex or concave shape. Therefore, even if the protective film member 10A is deformed by the internal stress of the film Sa, the diaphragm 2 will release its adhesion to the protective film member 10A before deforming in response to the deformation of the protective film member 10A (the protective film member 10A will peel off from the diaphragm 2). For example, in the case of a strong internal stress of tensile stress, as shown in FIG. 7, the protective film member 10A on which the film Sa is formed will only deform into a concave shape, but the diaphragm 2 will not deform. In addition, in the case of a strong internal stress of compressive stress, as shown in FIG. 8, the protective film member 10A on which the film Sa is formed will only deform into a convex shape, but the diaphragm 2 will not deform.

[0061] 〔effect〕 According to the present invention (the pressure sensor element 1A and the pressure sensor 100A using the same) configured as described above, the contained substance contained in the measurement fluid L is deposited on the protective film member 10A. Therefore, even if the contained substance is the film-forming substance S, the internal stress (tensile stress or compressive stress) of the generated film Sa acts on the diaphragm 2 through the protective film member 10A (in other words, the internal stress of the film does not directly act on the diaphragm 2). Here, the protective film member 10A is attached to the diaphragm 2 by an adhesive force f. However, as described above, this adhesive force f is set so that when the internal stress of the film acts on the protective film member 10A, the protective film member 10A peels off from the diaphragm 2. Therefore, the diaphragm 2 is not deformed by the internal stress of the film acting through the protective film member 10A. As described above, the pressure sensor element 1A according to the present invention and the pressure sensor 100A using the same can prevent a zero-point shift in the sensor output due to the internal stress of the film.

[0062] Furthermore, according to the present invention having the above configuration, the above effects are achieved with a simple structure in which protective film members 10A, 10B, and 10C are provided to cover the pressure-receiving surface 2aa of the diaphragm 2. In addition, this structure does not include any factors that increase the resistance to the flow of the measurement fluid L. Therefore, according to the present invention having the above configuration, the above effects can be achieved with an inexpensive and highly responsive pressure sensor element and pressure sensor.

[0063] Furthermore, because the protective film members 10A, 10B, and 10C are made of thin metal films with a predetermined thickness, they will not peel off into particles like a thin film coated on the pressure-receiving surface, even when exposed to a measurement fluid L containing a large amount of chemical substances such as film-forming substances. This allows the above-mentioned effects to be maintained for a long time. Furthermore, since the pressure-receiving surface 2aa of the pressure sensor element 1A is protected by the protective film members 10A, 10B, and 10C, the lifespan of the pressure sensor element 1A is relatively extended compared to when these members are not present. Additionally, the protective film members 10A, 10B, and 10C are removable and can be replaced as needed. This allows the above-mentioned effects to be maintained for a long period of time without the need to replace the pressure sensor element 1A.

[0064] In addition, in the present invention having the above configuration, the newly provided protective film member 10A is formed from one of conventionally used materials, such as sapphire, polycrystalline alumina, or a nickel-based alloy. Furthermore, the protective film member 10A and the diaphragm 2 are attached to each other without the need for an adhesive, or if necessary, using an adhesive made of the above conventionally used material (e.g., a convex portion 10Ac attached by vapor deposition, etc.). This configuration minimizes the risk of unexpected by-products being generated due to chemical reactions between the components constituting the present invention and the film-forming substance contained in the measurement fluid L. Furthermore, as described above, the protective film member 10A does not peel off in particles like a coated thin film, so new contaminants are not generated from the protective film member 10A. This makes it possible to provide a highly reliable pressure sensor element 1A and a pressure sensor 100A using the same.

[0065] Second Embodiment Next, a capacitance-type pressure sensor element 1B, which is another preferred embodiment of the present invention, and a capacitance-type pressure sensor 100B using the same will be described as a second embodiment with reference to FIGS. 9 to 11. This pressure sensor element 1B has the same configuration as the pressure sensor element 1A according to the first embodiment, except for the material of the protective film member and the special configuration for taking predetermined measures described below. Therefore, the same components as those in the pressure sensor element 1A described above are given the same reference numerals, and their description will be omitted unless otherwise necessary. Furthermore, the pressure sensor 100B incorporating the pressure sensor element 1B is identical to the pressure sensor 100A according to the first embodiment described above, except for the pressure sensor element 1B. Therefore, the pressure sensor 100B is also shown in FIG. 6, and its description will be omitted. In the description of this embodiment, the front-rear direction, the up-down direction, and the left-right direction are defined as the depth direction, the up-down direction, and the left-right direction, respectively, relative to the paper surface of the pressure sensor element 1B shown in Figures 9 to 11. As in the first embodiment, the contents shown in each figure may differ from the actual product; for example, the aspect ratio may differ from the actual product, and the scale of each component may not necessarily be the same.

[0066] The pressure sensor element 1B shown in FIG. 9 is characterized in that the protective film member 10B is mainly made of a metal material different from that of the diaphragm 2. Like the pressure sensor element 1A according to the first embodiment, the diaphragm 2 is made of a material mainly made of sapphire, polycrystalline alumina, or a nickel-based alloy. In contrast, the protective film member 10B is made of a material mainly made of a nickel-based alloy when the diaphragm 2 is mainly made of sapphire, or a material mainly made of either sapphire or a nickel-based alloy when the diaphragm 2 is mainly made of polycrystalline alumina, or a material mainly made of sapphire when the diaphragm 2 is mainly made of a nickel-based alloy. The protective film member 10B is identical in shape to the protective film member 10A except for the material, and is made of a thin metal film member that is generally circular in plan view and large enough to cover substantially the entire pressure-receiving surface 2aa.

[0067] Here, the diaphragm 2 and the protective film member 10B, which are made primarily of different materials, have a relatively weaker attractive force due to surface free energy than the diaphragm 2 and the protective film member 10A, which are made primarily of the same material. Therefore, in order to bond the pressure-receiving surface 2aa of the diaphragm 2 and the contact surface 10Ba of the protective film member 10B with a desired adhesive force f, they may be configured to adhere to each other using, for example, electrostatic force.

[0068] Furthermore, depending on the contact area, it may not be easy to adhere the diaphragm 2 and the protective film member 10B with the desired adhesive force f, and it is possible that the protective film member 10B may peel off from the diaphragm 2 due to an external force other than the internal stress of the film. For this reason, in addition to using surface free energy or electrostatic force, measures may be taken to prevent the protective film member 10B from peeling off from the diaphragm 2 even when such an external force is applied, or to restrict the movement of the protective film member 10B so that it remains in a predetermined position even if it is peeled off (hereinafter referred to as "peeling prevention measures"). As these peeling prevention measures, for example, the first peeling prevention measure and the second peeling prevention measure described below may be considered.

[0069] 1. Measures to prevent peeling 10, an adhesive member 11A may be interposed over substantially the entire area between the diaphragm 2 and the protective film member 10B, and the adhesive member 11A may increase the adhesive force f between them, thereby preventing the protective film member 10B from peeling off from the diaphragm 2. The adhesive member 11A may be a thin film formed over substantially the entire area of ​​the contact surface 10Ba of the protective film member 10B by, for example, vapor deposition or sputtering, and made of the same material as the main component of the diaphragm 2. The adhesive member 11A may also be a thin film formed over substantially the entire area of ​​the pressure-receiving surface 2aa of the diaphragm 2 by, for example, vapor deposition or sputtering, and made of the same material as the main component of the protective film member 10B.

[0070] The adhesive member 11A and the diaphragm 2 (or the protective film member 10B) that are mainly made of the same material attract each other relatively strongly through surface free energy, and the desired adhesive force f (for example, a tensile adhesive strength of 100 N / m 2 The adhesive member 11A adheres to the protective film member 10B (or the diaphragm 2) with an adhesive force f corresponding to the adhesive force f between the adhesive member 11A and the diaphragm 2 (or the protective film member 10B) during the film formation process. This prevents the protective film member 10B from peeling off from the diaphragm 2 due to external forces other than the internal stress of the film.

[0071] Depending on the contact area between the pressure-receiving surface 2aa of the diaphragm 2 and the adhesive surface 11Aa of the adhesive member 11A, or the contact area between the contact surface 10Ba of the protective film member 10B and the adhesive surface 11Aa of the adhesive member 11A, they may adhere to each other with a force greater than expected, as in the first embodiment. In this case, the first to third processes performed on the contact surface 10Aa of the protective film member 10A and / or the pressure-receiving surface 2aa of the diaphragm 2 in the first embodiment may also be performed on the contact surface 10Ba of the protective film member 10B and / or the adhesive surface 11Aa of the adhesive member 11A and / or the pressure-receiving surface 2aa of the diaphragm 2. For example, the contact surface 10Ba and / or the adhesive surface 11Aa and / or the pressure-receiving surface 2aa are processed to have a predetermined roughness (e.g., an arithmetic mean roughness (Ra) of about several μm) (first process). Furthermore, the adhesive member 11A is partially formed on the contact surface 10Aa or the pressure-receiving surface 2aa by microfabrication, film-forming processing, etc., to form (process) the adhesive surface 11Aa with irregularities, or a portion of the contact surface 10Aa or the pressure-receiving surface 2aa is cut to form irregularities (second processing). Furthermore, the protective film member 10B is processed into a form in which convex and concave portions are formed while maintaining a substantially constant film thickness by mechanical processing microfabrication such as pressing and film-forming processing, etc. (third processing). By these processes, the contact area between the pressure-receiving surface 2aa and the adhesive surface 11Aa is adjusted to be small, and the adhesive force f is set to, for example, 100 N / m 2 The tensile adhesive strength can be set as follows:

[0072] The thickness T10B of the protective film member 10B when the first peeling prevention measure is taken is set, for example, as follows. That is, when the diaphragm 2 and the protective film member 10B are attached via the adhesive member 11A, they may deform integrally when the pressure of the fluid to be measured L is applied. In anticipation of such a situation, it is desirable to set the thickness T10B of the protective film member 10B in the same manner as in the first embodiment. Specifically, assuming that the Young's modulus of the diaphragm 2, the protective film member 10B, and the adhesive member 11A are equal, the thickness T10B of the protective film member 10B is set so that the moment of inertia I3 of the integrated diaphragm 2, the protective film member 10B, and the adhesive member 11A is 1.01 times or less the moment of inertia I2 of the diaphragm 2 alone. For example, when the protective film member 10B and the adhesive member 11A have the same thickness, the thickness T10B of the protective film member 10B is set to be 0.17% or less of the thickness T2 of the diaphragm 2. Similarly, the thickness T11A of the adhesive member 11A is set to be 0.17% or less of the thickness T2 of the diaphragm 2.

[0073] The adhesive member 11A may be replaced by an adhesive sheet 11B made of a substrate coated with a conventional adhesive, such as a rubber-based adhesive, an acrylic-based adhesive, a silicone-based adhesive, or a urethane-based adhesive. Alternatively, the adhesive member 11B may be a multilayered adhesive member 11B made by coating a substrate with a material suitable for the pressure-receiving surface 2aa of the diaphragm 2, made of sapphire, and a material suitable for the contact surface 10Aa of the protective film member 10A, made of a nickel-based alloy. If the adhesive member 11B is made of a flexible material with a small modulus of longitudinal elasticity, it will have little effect on the deformation of the diaphragm 2. In this case, the thickness T10B of the protective film member 10B can be set without considering the thickness of the adhesive member 11B.

[0074] <ii>Second peeling prevention measures 11 shows a pressure sensor element 1B to which a second peel-prevention measure has been taken. This second peel-prevention measure is characterized in that the protective film member 10B is attached to the adhesive member 11C at its outer periphery, and its center is spaced a predetermined distance (the thickness hc of the adhesive member 11C) from the pressure-receiving surface 2aa of the diaphragm 2 so as to be out of contact with the pressure-receiving surface 2aa. The adhesive member 11C is, for example, a thin metal piece that is approximately annular in plan view and has a thickness hc. It is made of the same material as the main component of the protective film member 10B and is joined to the inside of the first cylindrical inner circumferential wall surface 2w1 of the fixed portion 2b of the diaphragm 2 by laser welding or the like. In this embodiment, the adhesive member 11C is disposed outside the sensing unit 2a (deformation region 2aα) by, for example, setting the inner diameter of the first cylindrical inner circumferential wall surface 2w1, i.e., the outer diameter D2aa of the pressure-receiving surface 2aa, larger than the outer diameter D2ab of the measurement surface. Therefore, the outer peripheral edge of the adhesive member 11C has a shape complementary to the first cylindrical inner circumferential wall surface 2w1, and its outer diameter is substantially the same as the inner diameter (D2aa) of the first cylindrical inner circumferential wall surface 2w1. Furthermore, the inner diameter d11Ca of the adhesive member 11C is set larger than the outer diameter D2ab of the measurement surface that defines the sensing unit 2a (deformation region 2aα). The adhesive member 11C has a thickness hc smaller than the thickness TB10 of the protective film member 10B, and a chamfer R' is formed on its inner peripheral edge.

[0075] By taking the second peel prevention measures described above, the protective film member 10B and the adhesive member 11C, which are mainly made of the same material, attract each other relatively strongly through their surface free energy, thereby allowing the diaphragm 2 and the protective film member 10B to adhere with the desired adhesive force f. Furthermore, by adhering the diaphragm 2 and the protective film member 10B through the adhesive member 11C of the above-mentioned form, that is, the adhesive member 11C arranged outside the sensing unit 2a (deformation region 2aα), having a thin thickness hc, and having a chamfered inner peripheral edge R', even if they are not in contact with each other in a static state, the pressure of the fluid to be measured L is transmitted to the sensing unit 2a in a preferred form (for example, in the form of a uniformly distributed load) through the protective film member 10B. As a result, the same measurement accuracy as when the protective film member 10B is not interposed can be maintained. In addition, in order to further adjust the adhesive force f, the first to third processing performed on the contact surface 10Aa of the protective film member 10A and / or the pressure-receiving surface 2aa of the diaphragm 2 in the first embodiment may be appropriately performed on the contact surface 10Ba of the protective film member 10B and / or the adhesive surface 11Ca of the adhesive member 11C.

[0076] The thickness T10B of the protective film member 10B when the second peeling prevention measure is taken is set, for example, as follows. That is, the diaphragm 2 and the protective film member 10B are not in contact with each other in a static state, and even when the pressure of the measurement fluid L is applied and they come into contact with each other at the sensing portion 2a (deformation region 2aα), the adhesive force between the two portions, which are mainly composed of different metals, is small. Therefore, the thickness T10B can be set assuming that the diaphragm 2 and the protective film member 10B do not deform as a single unit at the sensing portion 2a (deformation region 2aα). That is, the thickness T10B can be set arbitrarily without being subject to thickness restrictions (such as a limit of 0.34% or less of the thickness T2 of the diaphragm 2) that take into account the effect on the accuracy of pressure measurement (pressure sensitivity).

[0077] 〔effect〕 The pressure sensor element 1B according to the second embodiment having the above-described configuration and the pressure sensor 100B using the same provide the same effects as the pressure sensor element 1A according to the first embodiment described above and the pressure sensor 100A using the same. Furthermore, by taking a second measure to prevent peeling, it is possible to achieve a configuration in which the diaphragm 2 and the protective film member 10B have a desired adhesive force f and do not deform as a unit in the sensing section 2a (deformation region 2aα). In this configuration, the thickness of the protective film member 10B can be set as desired, taking into account durability and other factors.

[0078] Third Embodiment Next, a capacitance-type pressure sensor element 1C, which is another preferred embodiment of the present invention, and a capacitance-type pressure sensor 100C using the same will be described as a first embodiment with reference to FIGS. 12 to 14. This pressure sensor element 1C is different from the pressure sensor element 1A according to the first embodiment in that the material of the protective film member is different and it has a special configuration for taking certain measures, which will be described later, but the other configurations are the same as those of the pressure sensor element 1A. Therefore, the same components as those of the pressure sensor element 1A according to the first embodiment described above are given the same reference numerals, and their description will be omitted unless otherwise necessary. Furthermore, the pressure sensor 100C incorporating the pressure sensor element 1C is the same as the pressure sensor 100A according to the first embodiment described above, except for the pressure sensor element 1C. Therefore, the pressure sensor 100C is also shown in FIG. 6, and its description will be omitted. In the description of this embodiment, the front-rear direction, the up-down direction, and the left-right direction are defined as the depth direction, the up-down direction, and the left-right direction, respectively, relative to the paper surface of the pressure sensor element 1C shown in Figures 12 to 14. As in the first embodiment, the contents shown in each figure may differ from the actual product; for example, the aspect ratio may differ from the actual product, and the scale of each component may not necessarily be the same.

[0079] The pressure sensor element 1C shown in FIG. 12 is characterized in that the diaphragm 2 and the protective film member 10C are made of different materials, and the protective film member 10C is made of a non-metallic material. Here, as described above, the diaphragm 2 is made of a material whose main component is one of sapphire, polycrystalline alumina, and a nickel-based alloy. In contrast, the protective film member 10C is made of a polymer material whose main component is, for example, a fluororesin. Note that the protective film member 10C is identical in shape to the protective film member 10A except for the material, and is made of a metallic thin film member that is approximately circular in plan view and large enough to cover substantially the entire area of ​​the pressure-receiving surface 2aa.

[0080] Similar to the adhesion between the diaphragm 2 and the protective film member 10B in the second embodiment described above, the attractive force between the diaphragm 2 and the protective film member 10C made of different materials due to surface free energy is smaller than that between the diaphragm 2 and the protective film member 10A made of the same material. Therefore, in order to bond the pressure-receiving surface 2aa of the diaphragm 2 and the contact surface 10Ca of the protective film member 10C with a desired adhesive force f, they may be configured to adhere to each other using, for example, electrostatic force.

[0081] Depending on the contact area, the adhesive force due to the surface free energy and the adhesive force due to the electrostatic force alone may not be enough to bond the diaphragm 2 and the protective film member 10C to a desired adhesive force f (for example, a tensile adhesive strength of 100 N / m 2 Therefore, in order to prevent the protective film member 10C from peeling off from the diaphragm 2 due to an external force other than the internal stress of the film, the above-mentioned first peel prevention measure and second peel prevention measure may be taken separately.

[0082] However, polymeric materials such as fluororesins generally have extremely low surface free energy, making the attractive force even weaker than that between dissimilar metals. Therefore, in addition to the measures mentioned above, the third measure to prevent peeling, etc., described below, may be taken separately.

[0083] <iii>3. Measures to prevent peeling 13, the third peeling prevention measure is characterized by providing a locking member 12 above the diaphragm 2. This restricts the protective film member 10C from moving beyond a certain distance along the axis Y of the pressure sensor element 1C.

[0084] The locking member 12 is, for example, a thin plate-like member having a cylindrical opening 12a in the approximate center, a substantially horizontal lower surface that abuts against the upper surface of the diaphragm 2, and a substantially horizontal upper surface that abuts against the second base plate 32, and its outer wall has substantially the same shape as that of the diaphragm 2 (the shape of the side wall of a square prism with sides of 1 cm in plan view). The diameter d12 of the opening 12a is set, for example, smaller than the outer diameter D10C of the protective film member 10C and also smaller than the outer diameter D10C' of the protective film member 10C when it is deformed into a convex or concave shape due to internal stress of the film. The locking member 12 and the diaphragm 2 are joined by an existing joining method, for example, welding, bolts, or snap joints.

[0085] The locking member 12 having the above-described configuration is disposed on the upper surface 2e of the diaphragm 2, for example, so that the axis of the opening coincides with the axis of the sensing portion 2a of the diaphragm 2 (i.e., so that both axes coincide with the axis of the pressure sensor 100C). This divides the space C2 into a cylindrical space C2a having an inner diameter d12 and a cylindrical space C2b having an inner diameter D2aa, and the outer peripheral edge of the protective film member 10C is accommodated in the space formed on the outer periphery of the space C2b, specifically, the space formed between the inner diameter D2aa and the inner diameter d12. As a result, the outer peripheral edge of the protective film member 10C faces the lower surface 12b of the locking member 12, and the movement of the protective film member 10C in the axial direction is restricted by the lower surface 12b.

[0086] Here, the distance CL between the lower surface 12b of the locking member 12 and the pressure-receiving surface 2aa of the diaphragm 2 should be set, for example, to be greater than the maximum deformation amount (more specifically, the maximum deformation amount in the axial direction of the pressure sensor element 1C) when internal stress of the membrane acts on the protective membrane member 10A. The maximum deformation amount can be calculated approximately by, for example, regarding the protective film member 10A as a beam and understanding that the internal stress of the film is equal to the stress generated on the surface of the protective film member 10A. Specifically, assuming that a tensile or compressive stress σ equal to the internal stress of the film is generated on the surface of the protective film member 10A, the bending moment M that generates this stress σ is calculated from the relational expression σ = M / Z (Z is the cross-sectional modulus of the diaphragm 2). Furthermore, the radius of curvature ρ corresponding to the deformation (deflection) of the diaphragm 2 is calculated from the relational expression M = EI / ρ (E is the longitudinal elastic modulus of the material forming the diaphragm 2, and I is the second moment of area of ​​the diaphragm 2).

[0087] 14, an elastic member 13 may be disposed between a surface 10Cb of the protective film member 10C facing the space C2 and the lower surface 12b of the locking member 12. The elastic member 13 may be, for example, annular in plan view, and may be formed so as to press the entire periphery of the surface 10Cb, or may be formed so as to press the surface 10Cb partially. Furthermore, the elastic force of the elastic member 13 may be adjusted to a desired adhesive force f (for example, a tensile adhesive strength of 100 N / m 2 It may be set to be equal to the adhesive force f) corresponding to

[0088] In addition, a configuration may be adopted in which an elastic member 13 is used to press a portion of the surface 10Cb so that a portion of the protective film member 10C does not peel off from the pressure-receiving surface 2aa even when the internal stress of the film acts. In this case, the portion pressed by the elastic member 13 should be located in a position and area that does not prevent the protective film member 10C from deforming due to the internal stress of the film. For example, the portion may be located in one place, and the area should be as small as possible (for example, 1 / 10 of the outer periphery length of the protective film member 10C). It is desirable that the area be limited to less than half the outer periphery length of the protective film member 10C at most. Furthermore, if the portion is divided into multiple locations, it is desirable that all of them be located on the same side of a line that bisects the protective film member 10C in a plan view.

[0089] The thickness T10C of the protective film member 10C may be set, for example, as follows. That is, even when the diaphragm 2 made of a predetermined metal material and the protective film member 10C made of a material mainly composed of a fluororesin with low surface free energy are brought into contact with each other at a predetermined pressure, the adhesive force between them is extremely small. Therefore, the thickness T10C can be set assuming that the two do not deform as a single unit. That is, the thickness T10C can be set arbitrarily without being subject to thickness restrictions (such as a restriction of 0.34% or less of the thickness T2 of the diaphragm 2) that take into account the effect on the accuracy of pressure measurement (pressure sensitivity).

[0090] 〔effect〕 The pressure sensor element 1C according to the third embodiment having the above-described configuration and the pressure sensor 100C using the same provide the same effects as the pressure sensor element 1A according to the first embodiment described above and the pressure sensor 100A using the same. Furthermore, according to the third embodiment, as described above, the diaphragm 2 and the protective film member 10C can be integrated and prevented from deforming, so the thickness of the protective film member 10C can be set arbitrarily taking into consideration durability and the like.

[0091] Other Embodiments In the fourth processing in the first embodiment and the second peel prevention measure in the second embodiment, the diaphragm 2 and the protective film member 10B are attached only at their peripheral edges, and are not in contact with each other in the sensing portion 2a (deformation region 2aα). Therefore, a different embodiment can be adopted in which they are bonded by a strong adhesive force f that does not separate them even due to the internal stress of the film. For example, in the fourth processing step, the surface area of ​​the contact surface 2ba of the diaphragm 2 is made larger than the pressure-receiving surface 2aa, thereby relatively increasing the area of ​​contact with the contact surface 10Aa of the protective film member 10A. Here, the contact surface 2ba is formed so that the separation distance Tc between the diaphragm 2 and the protective film member 10A in the sensing portion 2a (deformation region 2aα) is larger than the maximum deformation amount (more specifically, the maximum deformation amount in the axial direction of the pressure sensor element 1A) when internal stress of the membrane acts on the protective film member 10A. Note that the maximum deformation amount is approximately determined by regarding the protective film member 10A as a beam, as explained in the description of the distance CL between the lower surface 12b of the locking member 12 and the pressure-receiving surface 2aa of the diaphragm 2, for example.

[0092] Furthermore, the second peeling prevention measure in the second embodiment can also be implemented in a similar manner to the above. That is, by making the surface area of ​​the abutting surface 2ba of the diaphragm 2 larger than the pressure-receiving surface 2aa, the contact area between the contact surface 10Ba of the protective film member 10B and the adhesive surface 11Ca of the adhesive member 11C can be increased, and further, the thickness hc of the adhesive member 11C can be set so that the distance between the diaphragm 2 and the protective film member 10A in the sensing portion 2a (deformation region 2aα) is larger than the maximum deformation amount (more specifically, the maximum deformation amount in the axial direction of the pressure sensor element) when internal stress of the film acts on the protective film member 10A.

[0093] The above describes preferred embodiments of the present invention, focusing on the pressure sensor element 1A according to the first embodiment to the pressure sensor element 1C according to the third embodiment. However, the present invention is not limited to these embodiments, and various modifications are possible without departing from the spirit of the present invention. Furthermore, even configurations not directly described in the specification and drawings are within the scope of the technical concept of the present invention, as long as they achieve the functions and effects of the present invention. Furthermore, the embodiments described above and shown in the drawings can be combined with each other, as long as there is no contradiction in their purpose, configuration, etc.

[0094] For example, the third peel prevention measure taken in the third embodiment in which the diaphragm 2 and the protective film member 10B are mainly composed of different materials and the protective film member 10C is made of fluororesin may also be applied to the pressure sensor element 1B of the second embodiment in which the diaphragm 2 and the protective film member 10B are made of different metals.

[0095] In the third peeling prevention measure in the third embodiment, the locking member 12 is provided separately from the diaphragm 2, but the member may be molded integrally with the diaphragm 2. Also, a space equivalent to the space C2b may be formed by cutting the first cylindrical inner peripheral wall surface 2w1 or the like.

[0096] Furthermore, although the pressure sensor element according to the above embodiment and the capacitance-type pressure sensor using the same both use a capacitance-type sensing method, the present invention is not limited to this sensing method. For example, the present invention can be applied to all pressure sensor elements and pressure sensors using the same that have a sensing method that detects the deformation of a diaphragm as an electrical signal, such as a strain gauge type in which a resistance gauge is attached or a film is formed by sputtering or the like, or a semiconductor piezoresistance type. [Explanation of symbols]

[0097] 1A...pressure sensor element, 1B...pressure sensor element, 1C...pressure sensor element, 2...diaphragm, 2a...sensing portion, 2b...fixed portion, 2aa...pressure receiving surface, 2ab...measurement surface, 2ba...contact surface, 2w1...first cylinder inner peripheral wall surface, 2w2...second cylinder inner peripheral wall surface, 3...base, 3a...fixed surface, 4...sensor electrode portion, 4a...movable electrode, 4b...fixed electrode, 5...contact pad, 5a...contact pad, 5b...contact pad, 10A...protective film member, 10B...protective film member, 10C...protective film member, 10Aa...contact surface, 10Ab...contact surface, 10Ac...convex portion, 10Ad...concave portion, 10Ca...contact surface, 10Cb...surface, 20...casing, 20V ...introduction portion, 20W...reference vacuum chamber, 21...upper housing, 21a...large diameter cylindrical portion, 22...lower housing, 22a...stopper, 23...cover, 23a...electrode lead insertion hole, 30...base plate, 31...first base plate, 31a...introduction hole, 32...second base plate, 32a...introduction hole, 40...support diaphragm, 40a...introduction hole, 50...electrode lead portion, 51...electrode lead pin, 52...shield, 53...hermetic seal, 55...contact spring, 56...contact spring, 60...hermetic seal, 100A...pressure sensor, 100B...pressure sensor, 100C...pressure sensor, C1...capacitance chamber, C2...space.< / iii> < / ii> < / d> < / c>

Claims

1. a diaphragm having an area that deforms due to a difference between a pressure of a fluid applied to a first surface and a pressure applied to a second surface; a protective film member configured to cover at least a portion of the first surface of the diaphragm so that a film-forming substance contained in the fluid is deposited on the protective film member; a sensor portion disposed on a second surface of the diaphragm and configured to electrically detect deformation of the diaphragm; Equipped with The protective film member is attached to the first surface with a predetermined tensile adhesive strength such that at least a portion of the protective film member is peeled off from the first surface by the force acting when the film-forming substance forms a film.

2. A die having a region that deforms due to the difference between the pressure applied to the first surface and the pressure applied to the second surface. Ahram and a protective film member covering at least a portion of the first surface of the diaphragm; a sensor portion disposed on a second surface of the diaphragm and configured to electrically detect deformation of the diaphragm; Equipped with The protective film member has at least the same heat resistance and corrosion resistance as the diaphragm. and a material having a strength of at least a portion of the first surface of the ２ The pressure sensor element is removably attached with a tensile adhesive strength of .

3. A die having a region that deforms due to the difference between the pressure applied to the first surface and the pressure applied to the second surface. Ahram and a protective film member covering at least a portion of the first surface of the diaphragm; a second surface of the diaphragm for electrically detecting deformation of the diaphragm; The sensor part Equipped with The diaphragm and the protective film member are made of the same material as a main component, and the material is a primer. fiber, polycrystalline alumina or nickel-based alloy, The protective film member has a resistance of 100 N / m or less on at least a portion of the first surface. ２ The pressure sensor element is removably attached with a tensile adhesive strength of .

4. The pressure sensor element according to claim 1, The pressure sensor element, wherein the protective film member is detachably attached to at least a portion of the first surface with a tensile adhesive strength of up to 100 N / m 2 .

5. The pressure sensor element according to any one of claims 1 to 4, At least one of the protective film member and the member in contact therewith has a contact area adjusted. A pressure sensor element characterized by being processed for this purpose.

6. The pressure sensor element according to any one of claims 1 to 5, The thickness of the protective film member is 0.3 times the thickness of the deformable region of the diaphragm. A pressure sensor element characterized in that the upper limit is 4%.

7. A pressure sensor element according to any one of claims 1 and 3, and claims 4 to 6 which directly or indirectly cite claim 1 or 3, The protective film member has at least the same heat resistance and corrosion resistance as the diaphragm. A pressure sensor element formed from a material.

8. A pressure sensor element according to any one of claims 1 and 2, and claims 4 to 7 which directly or indirectly cite claim 1 or 2, The diaphragm and the protective film member are made of the same material as a main component, and the material is a primer. A pressure sensor element characterized by being made of fiber, polycrystalline alumina or nickel-based alloy.

9. A pressure sensor element according to claim 1 and any one of claims 4 to 7 which cite claim 1, The diaphragm and the protective film member are made of different materials as main components, The main component of the material is either sapphire, polycrystalline alumina, or a nickel-based alloy. The protective film member is mainly made of one of sapphire, nickel-based alloy, and fluororesin. A pressure sensor element characterized by:

10. The pressure sensor element according to claim 1, a base having a third surface opposite the second surface; A capacitance type pressure sensor element, characterized in that a pair of electrodes constituting the sensor section are disposed on the second surface and the third surface.

11. A pressure sensor element according to any one of claims 1 to 10; A case that defines a space through which the fluid, the pressure of which is to be measured, flows in and out together with the diaphragm. and A pressure sensor comprising: a support member for supporting a pressure sensor element on the casing.

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