Pressure sensor

Abstract

The invention provides a pressure sensor which can reduce zero offset caused by accumulation due to a film forming process. The present invention has: a sensor element; a shell (tube shell); a support diaphragm having an opening for guiding pressure; and a pedestal member which clamps and supports the diaphragm in cooperation with the sensor element. The sensor element is joined to the support diaphragm in a state of closing the opening of the support diaphragm. The pedestal member has a pressure guiding portion, and is joined to the support diaphragm such that the pressure guiding portion overlaps the opening portion of the support diaphragm. The pressure guide portion of the pedestal member is configured from a plurality of pressure guide holes having openings of the same shape. The plurality of pressure guide holes are disposed on a plurality of concentric circles coaxial with the center of the support diaphragm, and are disposed so as to be uniformly distributed per unit area of the opening plane of the support diaphragm.

Description

Technical Field

[0001] The present invention relates to a pressure sensor having a diaphragm in contact with a fluid to be measured. Background Art

[0002] Vacuum gauges using electrostatic capacitance pressure sensors are used, for example, in semiconductor manufacturing equipment. These vacuum gauges are used in film formation processes among the various processes performed by semiconductor manufacturing equipment, as well as in etching processes involving silicon wafers and the like. Film formation methods used in these processes include sputtering, chemical vapor deposition (CVD), and atomic layer deposition (ALD).

[0003] During the film formation and etching processes performed in semiconductor manufacturing equipment, the formed films and byproducts generated during the process accumulate to varying degrees within chambers, piping, and pumps, causing various problems. In particular, accumulation of these substances on the pressure-receiving surface of the diaphragm of the pressure sensor in the vacuum gauge that measures and controls process gas pressure is known to cause zero point shifts and changes in pressure sensitivity, significantly impacting film formation and etching quality.

[0004] In an attempt to suppress the effects of film buildup by structuring the pressure-bearing surface of a diaphragm in a diaphragm vacuum gauge, diaphragm structures such as those shown in Patent Documents 1 and 2 have been proposed. Patent Documents 1 and 2 describe methods in which beam structures are provided on the pressure-bearing surface of the diaphragm to form a table-shaped, inverted-conical, or square-wave-shaped structure, or a honeycomb shape, thereby segmenting the deposited film and suppressing the effects of film stress on the diaphragm. However, this approach is believed to be less effective in processes such as ALD that form similar films based on physical or chemical adsorption on a surface.

[0005] To suppress the influence of the deposited film, one approach is to provide a diaphragm with honeycomb-shaped projections and depressions, as disclosed in Patent Document 3. Patent Document 3 discloses a technique in which multiple honeycomb-shaped projections and depressions are provided on the diaphragm to adjust the moment generated on the diaphragm by the expansion and contraction of the deposited film.

[0006] Patent Document 4 discloses a technology that, rather than suppressing the deposition of a film, directs contaminants contained in the film-forming gas toward the diaphragm in a prescribed pattern, allowing the formation of a film and simultaneously reducing the zero offset of the sensor output. The device described in Patent Document 4 includes a baffle on the upstream side of the pressure sensor. The baffle is formed with multiple arc-shaped slots for gas passage. These slots are arranged in a concentric pattern extending radially outward from the center of the diaphragm. The arc length of each arc-shaped slot increases as it moves radially outward from the center of the diaphragm.

[0007] [Prior art literature]

[0008] [Patent Document]

[0009] [Patent Document 1] Japanese Patent Publication No. 2009-524024

[0010] [Patent Document 2] Japanese Patent Application Laid-Open No. 2008-107214

[0011] [Patent Document 3] Japanese Patent Application Laid-Open No. 2009-265041

[0012] [Patent Document 4] Japanese Patent No. 4607889 Summary of the Invention

[0013] [Problems to be solved by the invention]

[0014] The method described in Patent Document 3 achieves significant results by forming the concavities and convexities to ideal dimensions, evenly and uniformly, on a diaphragm. However, there are limits to reducing machining tolerances, resulting in disadvantages such as insufficient machining of the diaphragm's center due to manufacturing variations, which can prevent the torque adjustment effect from being achieved.

[0015] The effects of the technology described in Patent Document 4 were verified, and the details of the results will be described later. However, it was found that the effect of suppressing zero point offset was not improved, and it was determined that further improvement was required.

[0016] The influence caused by the accumulation of the byproducts described above leads to a decrease in the measurement accuracy of the pressure sensor. Therefore, in order to realize a vacuum gauge with high measurement accuracy, it is necessary to minimize the zero point offset, and improvements are required.

[0017] An object of the present invention is to provide a pressure sensor that reduces zero point offset caused by accumulation resulting from a film forming process.

[0018] [Technical means to solve the problem]

[0019] 20. The pressure sensor of the present invention comprises: a sensor element for detecting pressure; a tube shell for accommodating the sensor element; and a support structure for supporting the sensor element in the tube shell, the support structure comprising: a support diaphragm whose outer edge is fixed to the tube shell and has an annular opening in the center; and a base member for clamping the support diaphragm in cooperation with the sensor element, the sensor element being joined to the support diaphragm in a state of blocking the opening of the support diaphragm, the base member having a pressure guiding portion and being joined to the support diaphragm in a manner that the pressure guiding portion and the opening of the support diaphragm overlap, in the pressure sensor, the pressure guiding portion of the base member is composed of a plurality of pressure guiding holes of the same shape, the pressure guiding holes being arranged on a plurality of concentric circles coaxial with the center of the base member, and being arranged so as to be evenly distributed per unit area of ​​the opening plane of the pressure guiding portion of the base member.

[0020] In order to achieve the above object, the pressure sensor of the present invention includes: a sensor element for detecting pressure; a tube shell for accommodating the sensor element; and a support structure for supporting the sensor element in the tube shell, the support structure having: a support diaphragm formed in a flat plate shape having an opening for guiding pressure, and an outer edge portion of which is fixed to the tube shell; and a base member for clamping the support diaphragm in cooperation with the sensor element, the sensor element being joined to the support diaphragm in a state of blocking the opening portion of the support diaphragm, the base member having a pressure guiding portion and being joined to the support diaphragm in a manner that the pressure guiding portion and the opening portion of the support diaphragm overlap, in the pressure sensor, the opening portion of the support diaphragm is composed of a plurality of pressure guiding holes having openings of the same shape, the pressure guiding holes being arranged on a plurality of concentric circles coaxial with the center of the support diaphragm, and being arranged so as to be evenly distributed per unit area of ​​the plane of the pressure guiding hole openings of the support diaphragm.

[0021] In the present invention, in the pressure sensor, the opening shape of the pressure guide hole may be circular.

[0022] In the present invention, in the pressure sensor, the opening shape of the pressure guide hole may be polygonal.

[0023] The present invention may be that, in a pressure sensor, the sensor element has: a first circular recess, an opening portion of which is closed by the supporting diaphragm; a second circular recess, which is open to the side opposite to the supporting diaphragm; and a sensor diaphragm, which is formed in a portion that becomes the boundary between the first circular recess and the second circular recess, the inner diameter of the first circular recess is formed to be larger than the inner diameter of the second circular recess, and the pressure guide hole is also formed radially outward of the second circular recess when viewed in the thickness direction of the supporting diaphragm.

[0024] [Effects of the Invention]

[0025] According to the present invention, a pressure sensor can be provided which reduces zero point offset caused by accumulation resulting from a film forming process. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a cross-sectional view of the pressure sensor of the present invention.

[0027] Figure 2 This is an exploded perspective view of the sensor element and supporting structure.

[0028] Figure 3 It is a three-dimensional cross-sectional view of the sensor element and supporting structure.

[0029] Figure 4 It is a plan view of the pedestal component.

[0030] Figure 5 This is a graph showing the relationship between changes in the shape and arrangement of the pressure guide holes and the magnitude of the zero point offset.

[0031] Figure 6 This is an exploded perspective view of the sensor element and the support structure according to the second embodiment.

[0032] Figure 7 It is a plan view of the pedestal component.

[0033] [Explanation of Symbols]

[0034] 1: Pressure sensor

[0035] 2: Shell (tube shell)

[0036] 4: Support diaphragm

[0037] 9: Sensor element

[0038] 12: Support structure

[0039] 13: Opening

[0040] 16: Pedestal components

[0041] 17: Pressure guide hole

[0042] 18: Pressure guide part

[0043] 23: First circular recess

[0044] 24: Second circular concave part

[0045] 25: Sensor diaphragm DETAILED DESCRIPTION

[0046] (First embodiment)

[0047] Below, refer to Figures 1 to 5 , an embodiment of the pressure sensor of the present invention is described in detail.

[0048] Figure 1 The pressure sensor shown is a so-called electrostatic capacitance type pressure sensor. Figure 1 The outermost casing 2 as a tube shell is constructed by incorporating various functional components.

[0049] The housing 2 includes a cylindrical upper housing 3. Figure 1 The uppermost portion of the housing 5 is shown in FIG. 1 ; a cylindrical lower housing 5 is welded to the upper housing 3 with the support diaphragm 4 sandwiched therebetween; and a cover 6 closes the opening of the lower housing 5 . Electrode terminals 7 for signal transmission extend through the cover 6 . The electrode terminals 7 are connected to a sensor element 9 described later via a conductive contact spring 8 .

[0050] The end portion of the upper case 3 on the opposite side to the lower case 5 serves as an introduction portion 11 into which the fluid to be measured is introduced.

[0051] The support diaphragm 4 forms part of a support structure 12 that supports the sensor element 9 within the housing 2. Figure 2 As shown in FIG. 1 , the support diaphragm 4 according to this embodiment is formed into a ring shape having one opening 13 for guiding pressure, and the outer edge thereof is fixed to the housing 2. Figure 1 As shown, the supporting diaphragm 4 divides the housing 2 into a fluid chamber 14 communicating with the introduction portion 11 and a vacuum chamber 15 in the lower housing 5. The fluid to be measured is introduced into the fluid chamber 14, and the vacuum chamber 15 is maintained at a predetermined vacuum level.

[0052] The support structure 12 includes a support diaphragm 4 and a pedestal member 16 that cooperates with the sensor element 9 to clamp the outer edge of the opening 13 in the center of the support diaphragm 4. The sensor element 9 and the pedestal member 16 are joined in a manner that surrounds the opening 13 in the center of the support diaphragm 4. Figure 3 As shown, the base member 16 according to this embodiment has a pressure guiding portion 18 including a plurality of pressure guiding holes 17, and is joined to the surface 4a of the support diaphragm 4 on the fluid chamber 14 side so that the pressure guiding portion 18 overlaps with the opening 13 of the support diaphragm 4. The pressure guiding portion 18 will be described later.

[0053] The sensor element 9 is bonded to the surface 4b of the support diaphragm 4 on the vacuum chamber 15 side, blocking the opening 13 of the support diaphragm 4. The pedestal member 16 of this embodiment and the sensor element 9 are formed to have the same shape when viewed in the thickness direction of the support diaphragm 4.

[0054] By bonding the base member 16 and the sensor element 9 to both sides of the support diaphragm 4 , the interior of the housing 2 is airtightly partitioned into a fluid chamber 14 and a vacuum chamber 15 .

[0055] The sensor element 9 adopts a structure for detecting based on the electrostatic capacitance that changes according to the pressure difference between the fluid to be measured and the vacuum chamber. Figure 3 As shown, sensor element 9 includes: a sensor diaphragm 25, which bends toward vacuum chamber 15 in response to the pressure difference between the pressure of the measured fluid on the pressure-receiving surface on the fluid chamber 14 side and the pressure on the pressure-receiving surface on the vacuum chamber 15 side; a sensor diaphragm support portion 21, which is the outer edge of sensor diaphragm 25 and has one end surface bonded to surface 4b of support diaphragm 4 on the vacuum chamber 15 side; and a sensor base 22, which is bonded to the other end surface of sensor diaphragm support portion 21. Sensor diaphragm support portion 21 and sensor base 22 are formed of, for example, sapphire.

[0056] A first circular recess 23 is formed by the pressure-receiving surface of the sensor diaphragm 25 on the fluid chamber 14 side and the inner wall of the sensor diaphragm support portion 21 on the fluid chamber 14 side. A second circular recess 24 is formed by the pressure-receiving surface of the sensor diaphragm 25 on the vacuum chamber 15 side and the inner wall of the sensor diaphragm support portion 21 on the vacuum chamber 15 side. The centers of the first and second circular recesses 23 and 24 are aligned on the same axis as the center of the support diaphragm 4.

[0057] The opening of the first circular recess 23 is closed by the base member 16. The opening of the second circular recess 24 is closed by the sensor base 22. The inner diameter D1 of the first circular recess 23 is larger than the inner diameter D2 of the second circular recess 24. In this embodiment, the inner diameter D1 of the first circular recess 23 is equal to the inner diameter D3 of the opening of the support diaphragm 4 (see FIG. Figure 2 ) are roughly equal.

[0058] Furthermore, a thin disk-shaped portion serving as a boundary between the first circular recess 23 and the second circular recess 24 forms the sensor diaphragm 25 .

[0059] The size of the movable portion of the sensor diaphragm 25 according to this embodiment is determined by the inner diameter of the second circular recess 24. In other words, the outer circumference of the circular bottom surface of the first circular recess 23 relative to the inner diameter of the second circular recess 24 does not function as the sensor diaphragm 25.

[0060] One end surface of the sensor diaphragm support portion 21 is bonded to the support diaphragm 4 , and a space surrounded by the sensor diaphragm 25 , the inner wall of the sensor diaphragm support portion 21 on the fluid chamber 14 side, and the base member 16 forms a pressure introduction chamber 26 .

[0061] On the other hand, the other end surface of the sensor diaphragm support portion 21 is joined to the sensor base 22, and the space enclosed by the sensor diaphragm 25, the inner wall of the sensor diaphragm support portion 21 on the vacuum chamber 15 side, and the sensor base 22 forms a reference vacuum chamber 27. The reference vacuum chamber 27 communicates with the vacuum chamber 15 via a through hole (not shown) that penetrates the sensor base 22.

[0062] Electrodes 28 and 29 for measuring capacitance are provided on the facing surfaces of the sensor diaphragm 25 and the sensor base 22, respectively. These electrodes 28 and 29 cooperate to function as a capacitor and are electrically connected to the contact spring 8 via a conductor (not shown). Therefore, data on the capacitance of the capacitor formed by electrodes 28 and 29, detected by the sensor element 9, is transmitted from the sensor element 9 to a measurement circuit (not shown) via the conductor (not shown), the contact spring 8, and the electrode terminal 7 of the cover 6.

[0063] The base member 16 is formed into a plate shape by, for example, sapphire. Figure 3 As shown, a plurality of pressure guide holes 17 constituting the pressure guide portion 18 of the base member 16 are formed to penetrate the base member 16 in the thickness direction. All pressure guide holes 17 have the same circular opening shape and the same hole diameter.

[0064] like Figure 4 As shown, the plurality of pressure guiding holes 17 formed in the pressure guiding portion 18 of the pedestal member 16 are formed based on the following predetermined rule. The rule for forming the pressure guiding holes 17 is as follows: the plurality of pressure guiding holes 17 having openings of the same shape are arranged on a plurality of concentric circles coaxial with the center C of the pedestal member 16, and the pressure guiding holes 17 are arranged so as to be evenly distributed per unit area of ​​the opening plane 16a of the pressure guiding portion 18 of the pedestal member 16.

[0065] The so-called "a plurality of concentric circles coaxial with the center C of the pedestal member 16" mentioned here is as follows: Figure 4 Indicated by the two-dot chain lines are multiple imaginary circles 31 to 36 coaxial with the center C of the base member 16 and having different diameters. Furthermore, the "opening plane 16a of the pressure guiding portion 18 of the base member 16" refers to the surface 16a of the base member 16 where the openings of the pressure guiding holes 17 provided in the pressure guiding portion 18 are formed. Furthermore, the phrase "equally distributed per unit area" means that when the opening plane 16a is divided into frames enclosing a space of a predetermined unit area, the number of pressure guiding holes 17 within each frame is the same across all frames.

[0066] Furthermore, when viewed from a direction perpendicular to the opening plane 16a (the thickness direction of the support diaphragm 4), the outer edge of the range of the pressure guide portion 18 where the plurality of pressure guide holes 17 are formed is near the inner side of the opening 13 of the support diaphragm 4. Figure 4 In FIG. 4 , the position of the opening 13 of the support diaphragm 4 is indicated by a dotted line L1, and the position of the outer peripheral surface of the second circular recess 24 of the sensor element 9 is indicated by a dotted line L2. Figure 4 As shown, the plurality of pressure-introducing holes 17 are also formed radially outward of the second circular recess 24 when viewed in the thickness direction of the base member 16 .

[0067] The size of the movable portion of the sensor diaphragm 25 is determined by the inner diameter of the second circular recess 24. That is, a portion of the outer circumference of the circular bottom surface of the first circular recess 23 (a portion radially outward from the second circular recess 24) does not function as the sensor diaphragm 25.

[0068] In the thus configured electrostatic capacitance pressure sensor 1, the measured fluid introduced into the housing 2 through the inlet portion 11 of the housing 2 flows into the pressure introduction chamber 26 of the sensor element 9 via the plurality of pressure guide holes 17 of the base member 16 and the opening 13 of the support diaphragm 4. Furthermore, depending on the magnitude of the pressure difference between the pressure of the measured fluid in the pressure introduction chamber 26 and the pressure (vacuum) of the reference vacuum chamber 27, the sensor diaphragm 25 is displaced, deflecting toward the reference vacuum chamber 27. The pressure sensor 1 measures the pressure of the measured fluid based on the displacement of the sensor diaphragm 25.

[0069] Here, if the measured fluid contains a film-forming substance, the film-forming substance flows into pressure inlet chamber 26 along with the measured fluid, contacts the circular bottom surface of first circular recess 23, i.e., the pressure-receiving surface of sensor diaphragm 25, and ultimately accumulates on the pressure-receiving surface to form a film. Furthermore, the wider the film formed on the pressure-receiving surface of sensor diaphragm 25 and the thicker the film, the greater the stress applied to sensor diaphragm 25, causing deflection (zero offset) of sensor diaphragm 25 unrelated to the pressure of the measured fluid, ultimately degrading the measurement accuracy of pressure sensor 1. Therefore, to mitigate the adverse effects of zero offset on pressure sensor 1 caused by the accumulation of film-forming substance on the pressure-receiving surface of sensor diaphragm 25, it is important to limit the film-forming area so that it does not expand and the film-forming area on the pressure-receiving surface of sensor diaphragm 25 does not become positionally biased. The film formation condition and film formation position of the film-forming material on the pressure-receiving surface of the sensor diaphragm 25 depend on the position and shape of the opening of the pressure guide hole 17 formed in the base member 16 as the terminal of the flow path of the measured fluid into the pressure introduction chamber 26.

[0070] Therefore, focusing on the above-mentioned aspects, the position and shape of the opening of the pressure guide hole 17 formed in the base member 16 that can effectively alleviate the influence of the zero point offset on the pressure sensor 1 were explored, and the result was that Figures 1 to 4 The first embodiment is shown.

[0071] According to this embodiment, the film-forming substance mixed in the measured fluid is dispersed into the plurality of pressure-conducting holes 17 formed in the base member 16 and flows into the pressure introduction chamber 26. However, the dispersed film-forming substance is deposited on the pressure-receiving surface of the sensor diaphragm 25 within the area perpendicular to the opening of each pressure-conducting hole 17, and forms a film there. In other words, films of a size corresponding to the number of pressure-conducting holes 17 are dispersed and formed on the pressure-receiving surface of the sensor diaphragm 25 (in terms of the area of ​​the opening of the pressure-conducting holes 17). Figure 4 The arrangement pattern of the pressure-guiding holes 17 of the pressure-guiding portion 18 (shown in the figure) allows for the formation of films on the pressure-receiving surface of the sensor diaphragm 25. Consequently, the range of each film formation is narrow. Furthermore, because adjacent films are isolated, they do not connect to form a large film. Furthermore, the films are evenly distributed across the surface of the sensor diaphragm 25. Therefore, the sensor diaphragm 25 is not affected by the film, or any effect is negligible. Consequently, zero offset is reduced.

[0072] Therefore, according to this embodiment, a pressure sensor can be provided that reduces the zero point offset caused by the buildup caused by the film formation process.

[0073] Furthermore, the relationship between the shape and arrangement of the pressure guide hole 17 formed in the base member 16 and the zero point offset was simulated, and the following results were obtained: Figure 5 The results shown.

[0074] exist Figure 5 A graph showing the relationship between the eight types of pressure-conducting holes 17 and the zero-point offset is described in the upper portion of FIG. , and schematic diagrams showing the four typical types of pressure-conducting holes 17 are shown in the lower portion.

[0075] When the four types of pressure guide holes 17 are used, Figure 5 The configuration indicated by symbol 1 and depicted on the far left in the graph, i.e., when the pressure guide holes 17 are sparsely arranged on the center side of the base member 16 and densely arranged on the outer periphery, a large zero offset is observed in the negative region. The configuration of the pressure guide holes 17 is similar to the configuration described in Patent Document 4, which comprises multiple arc-shaped elongated holes. Therefore, the configuration in Patent Document 4 results in a large zero offset.

[0076] When the number of pressure guide holes 17 formed on the center side of the pedestal member 16 is increased and the number of pressure guide holes 17 formed on the outer peripheral side of the pedestal member 16 is reduced compared to the case where the leftmost form of the four forms of pressure guide holes 17 is adopted, as shown in FIG. Figure 5 As shown by symbol 2 in the graph of , the zero point offset gradually decreases in the negative region. Figure 5In the diagram of FIG. 3 , the pressure guide holes 17 are formed uniformly in the base member 16 ( Figures 1 to 4 In the embodiment shown in the figure, the zero point offset is slightly generated in the positive region. This degree of zero point offset is negligible.

[0077] When the number of pressure-guiding holes 17 formed on the center side of the pedestal member 16 is further increased and the number of pressure-guiding holes 17 formed on the outer peripheral side of the pedestal member 16 is further reduced, so that the pressure-guiding holes 17 become dense on the center side of the pedestal member 16 and sparse on the outer peripheral side, the zero point offset is determined as follows: Figure 5 In the graph of , as indicated by symbols 4 to 7, it becomes larger in the positive region.

[0078] As in Figure 5 As shown by reference numeral 8 in the graph, when the pressure guide holes 17 are formed at four locations of the base member 16, it is determined that a non-negligible zero point offset occurs in the negative region.

[0079] By uniformly forming the pressure-conducting holes 17 in the base member 16 in this manner, the zero-point offset can be reduced to a negligible level.

[0080] (Second embodiment)

[0081] The pressure guide hole can also be Figure 6 Instead of being provided on the pedestal member 16 as shown in the first embodiment, the support diaphragm is provided as shown in FIG. Figure 6 In the Figures 1 to 5 The same or equivalent components as those already described are denoted by the same reference numerals, and detailed description thereof will be appropriately omitted.

[0082] Figure 6 The support diaphragm 4 shown is formed in a disk shape and has an opening 13 including a plurality of pressure-conducting holes 17 at its center. Figure 6 The seat member 16 shown is formed in an annular shape and has a pressure guide portion 18 including a single hole in the center.

[0083] The multiple pressure-conducting holes 17 provided in the support diaphragm 4 are formed to penetrate the support diaphragm 4 in the thickness direction. Furthermore, all pressure-conducting holes 17 have the same circular opening shape and the same diameter. These pressure-conducting holes 17 are formed according to the same rules as those used in the first embodiment. Specifically, the pressure-conducting holes 17 are arranged on multiple concentric circles coaxial with the center of the support diaphragm 4, and the pressure-conducting holes 17 are evenly distributed per unit area of ​​the pressure-conducting hole opening plane 4a (the surface facing the fluid chamber 14) of the support diaphragm 4.

[0084] The multiple pressure-conducting holes 17 provided in the support diaphragm 4 are formed within a circular area when viewed in the thickness direction of the support diaphragm 4. The outer edge of this circular area, when viewed in the thickness direction of the support diaphragm 4, coincides with the outer edge of the first circular recess 23 formed in the sensor element 9. In other words, the multiple pressure-conducting holes 17 of the support diaphragm 4 are also formed radially outward of the second circular recess 24 of the sensor element 9 when viewed in the thickness direction of the support diaphragm 4.

[0085] Furthermore, in the second embodiment, as in the first embodiment, the inner diameter of the first circular recess 23 of the sensor element 9 is larger than the inner diameter of the second circular recess 24. The pressure guide hole 17 is also formed radially outward of the second circular recess 24, as viewed in the thickness direction of the support diaphragm 4 (the thickness direction of the base member 16).

[0086] Therefore, in the case of adopting this embodiment, when the measured fluid contains a film-forming substance, the film-forming substance mixed in the measured fluid is dispersed into the multiple pressure-conducting holes 17 formed in the support diaphragm 4 and flows into the pressure introduction chamber 26. However, these dispersed film-forming substances also accumulate on the pressure-receiving surface of the sensor diaphragm 25 within the area perpendicular to the opening of each pressure-conducting hole 17, and form a film there. That is, on the pressure-receiving surface of the sensor diaphragm 25, films of an area corresponding to the number of pressure-conducting holes 17 are dispersed and formed (in terms of the area of ​​the opening of the pressure-conducting holes 17). Figure 4 The arrangement pattern of the pressure-guiding holes 17 of the pressure-guiding portion 18 (shown in the figure) allows for the formation of films on the pressure-receiving surface of the sensor diaphragm 25. Consequently, the range of each film formation is narrow. Furthermore, because adjacent films are isolated, they do not connect to form a large film. Furthermore, the films are evenly distributed across the surface of the sensor diaphragm 25. Therefore, the sensor diaphragm 25 is not affected by the film, or any effect is negligible. Consequently, zero offset is reduced.

[0087] Therefore, according to this embodiment, a pressure sensor can be provided that reduces the zero point offset caused by the buildup caused by the film formation process.

[0088] In the first and second embodiments, the pressure guide hole 17 is exemplified as having a circular opening, but the shape of the pressure guide hole 17 is not limited thereto. Figure 7 As shown in FIG. 1 , a form having polygonal openings such as hexagonal openings may also be adopted.

Claims

1. A pressure sensor comprising: A sensor element to detect pressure; a tube shell, accommodating the sensor element; as well as a supporting structure for supporting the sensor element in the tube shell, The support structure has: a supporting diaphragm having an outer edge portion fixed to the tubular housing and an annular shape with an opening at the center; and a pedestal member, cooperating with the sensor element to clamp the support diaphragm, The sensor element is bonded to the support film in a state of blocking the opening of the support film. The pedestal member has a pressure guide portion and is joined to the support diaphragm in such a manner that the pressure guide portion overlaps with the opening of the support diaphragm. The pressure sensor is characterized in that the pressure guide portion of the base member is composed of a plurality of pressure guide holes of the same shape. The pressure-guiding holes are arranged on a plurality of concentric circles coaxial with the center of the pedestal member, and are arranged to be evenly distributed per unit area of ​​an opening plane of the pressure-guiding portion of the pedestal member.

2. A pressure sensor comprising: A sensor element to detect pressure; a tube shell, accommodating the sensor element; as well as a supporting structure for supporting the sensor element in the tube shell, The support structure has: A supporting diaphragm is formed in a flat plate shape having an opening for guiding pressure, and an outer edge portion of the supporting diaphragm is fixed to the tube case; as well as a pedestal member, cooperating with the sensor element to clamp the support diaphragm, The sensor element is bonded to the support film in a state of blocking the opening of the support film. The pedestal member has a pressure guide portion and is joined to the support diaphragm in such a manner that the pressure guide portion overlaps with the opening of the support diaphragm. The pressure sensor is characterized in that the opening portion of the support diaphragm is composed of a plurality of pressure-conducting holes having openings of the same shape. The pressure-conducting holes are arranged on a plurality of concentric circles coaxial with the center of the supporting diaphragm, and are arranged to be evenly distributed per unit area of ​​the pressure-conducting hole opening plane of the supporting diaphragm.

3. The pressure sensor according to claim 1 or 2, characterized in that: The opening shape of the pressure-guiding hole is circular.

4. The pressure sensor according to claim 1 or 2, characterized in that: The opening shape of the pressure-guiding hole is polygonal.

5. The pressure sensor according to claim 1 or 2, characterized in that: The sensor element has: a first circular recess, the opening of which is closed by the supporting membrane; a second circular recess, opening toward a side opposite to the supporting diaphragm; as well as The sensor membrane is formed at a portion forming a boundary between the first circular recess and the second circular recess. The inner diameter of the first circular recess is formed to be larger than the inner diameter of the second circular recess. The pressure guiding hole is also formed radially outward of the second circular recess when viewed in the thickness direction of the support diaphragm.

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