Sensor components and physical quantity sensors

Abstract

To provide a sensor member with which it is possible to suitably prevent a problem of moisture content infiltrating via an interface between an electrode and a protective film.SOLUTION: There is provided a sensor member comprising: a protected part that is provided to one plane of a metal substrate and has a detection part; a protective film that has a first protective film section having a first thickness and a second protective film section having a second thickness thicker than the first thickness and that is formed at a peripheral edge of an opening that leads to the protected part, the protective film covering at least a part of the protected part from above; and an electrode part that has a first electrode section located at the opening and connecting to the protected part, and a second electrode section connecting to the first electrode section at an outer peripheral edge of the first electrode section and formed on top of the second protective film section.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a physical quantity sensor and a sensor member constituting the physical quantity sensor.

Background Art

[0002] As a sensor member constituting a physical quantity sensor such as a pressure sensor, one formed on a metal substrate through a film forming process or the like is known. Among such sensor members, there are those that require high reliability even in harsh environments such as high temperature and high humidity environments.

[0003] As a technique for improving the reliability of a sensor member, a technique of providing a protective film for protecting a detection part has been proposed (see Patent Document 1 etc.). However, since an electrode for ensuring electrical connection to the detection part cannot be completely covered with a protective film or the like, moisture or the like may enter through the interface between the electrode and the protective film, which has been an issue in improving reliability.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In view of such a situation, the present invention provides a sensor member or the like that can suitably prevent problems such as moisture from entering through the interface between an electrode and a protective film.

Means for Solving the Problems

[0006] The sensor member according to the present invention is provided on one surface of a metal substrate, and includes a protected part having a detection part, A protective film having a first protective film portion having a first thickness, and a second protective film portion having a second thickness greater than the first thickness and formed on the periphery of the opening leading to the protected portion, the protective film covering at least a part of the protected portion from above, The electrode portion includes a first electrode portion positioned in the opening and connected to the protected portion, and a second electrode portion connected to the first electrode portion at its outer peripheral edge and formed on the second protective film portion.

[0007] In the sensor member according to the present invention, as can be understood from the relationship between the second protective film portion and the second electrode portion, the electrode portion is formed on the protective film, so the area of ​​the opening formed in the protective film can be made smaller than the exposed area of ​​the electrode portion when viewed from above. Furthermore, the protective film has a second protective film portion with a greater thickness around the opening for the electrode portion to connect to the protected portion. In a sensor member having such a structure, the distance over which the interface between the protective film formed around the opening and the electrode portion shields the protected portion is long, so the problem of moisture and other substances entering through the interface can be effectively prevented.

[0008] Furthermore, for example, the outer electrode surface of the electrode portion that does not face the protective film and the outer protective film surface of the protective film that does not face the electrode portion may be connected without forming a step at the outer peripheral edge of the interface between the electrode portion and the protective film.

[0009] Because the outer electrode surface and the outer protective film surface are connected without forming a step at the outer edge of the interface, the problem of moisture accumulating in the step entering the interface can be effectively prevented, thereby improving reliability.

[0010] Furthermore, for example, when viewed from above, the outer edge of the second electrode portion, which is also the outer edge of the electrode portion, may coincide with the outer edge of the second protective film portion.

[0011] In such sensor components, the thickness of the protective film decreases at a position corresponding to the outer edge of the electrode portion, which prevents the formation of depressions or other areas where moisture can easily accumulate at the outer edge of the interface.

[0012] Furthermore, for example, the protective film may have a third protective film portion that connects the first protective film portion and the second protective film portion, with the thickness of the protective film transitioning from a first thickness at the connection point with the first protective film portion to a second thickness at the connection point with the second protective film portion.

[0013] In such sensor components, the thickness of the protective film changes smoothly, which can more effectively prevent crack formation due to stress concentration in the protective film and improve reliability.

[0014] Furthermore, for example, the electrode portion may contain any of Au, Ag, Cu, or Pd.

[0015] Such electrode portions are relatively soft, which improves adhesion with the protective film. Furthermore, because such electrode portions are chemically stable, they contribute to improving the reliability of the sensor component.

[0016] Furthermore, the protective film may be made of an oxide, a nitride, or an oxynitride.

[0017] Because such protective films have high strength, they can improve structural strength, especially around openings, and thus improve the reliability of the sensor components.

[0018] Furthermore, for example, an adhesion layer may be formed at the interface between the electrode portion and the protective film.

[0019] This adhesive layer improves the adhesion strength between the protective film and the electrode portion, thereby more effectively preventing problems such as moisture entering through the interface.

[0020] Furthermore, for example, the protected portion may include an insulating film that covers one of the surfaces from above, and a strain-resistant film formed on the insulating film and constituting the detection portion.

[0021] An insulating film ensures insulation from the metal substrate, and a strain resistance film forms the detection part. Such a sensor member can detect physical quantities associated with deformation of the metal substrate even in harsh environments such as high-temperature and high-humidity environments.

[0022] Also, for example, the detection part may detect the pressure acting on the metal substrate.

[0023] Such a sensor member realizes a highly reliable pressure sensor that can perform stable detection even when installed in a harsh environment such as a high-temperature and high-humidity environment for a long time.

Brief Description of the Drawings

[0024] [Figure 1] FIG. 1 is a schematic cross-sectional view of a pressure sensor including a sensor member according to an embodiment of the present invention. [Figure 2] FIG. 2 is a plan view of the sensor member included in the pressure sensor shown in FIG. 1 as viewed from above. [Figure 3] FIG. 3 is a partial cross-sectional view of the sensor member shown in FIG. 1. [Figure 4] FIG. 4 is a partial cross-sectional view of a sensor member according to a modified example.

Mode for Carrying Out the Invention

[0025] Hereinafter, the present invention will be described based on the embodiments shown in the drawings.

[0026] Figure 1 is a schematic cross-sectional view of a pressure sensor 10 using a sensor member 18 according to one embodiment of the present invention. As shown in Figure 1, the pressure sensor 10 has a hollow cylindrical stem 20. The stem 20 is made of a metal such as steel, aluminum alloy, stainless steel, or nickel alloy. The stem 20 has a membrane 22 that forms an end wall located at one end of the hollow cylinder, and the membrane 22 deforms in response to pressure. As will be described later, the membrane 22 constitutes a metal substrate on which the detection part 33 of the sensor member 18 is provided. As the metal substrate of the sensor member 18, the metals mentioned above can be used as the material of the stem 20, but in particular, austenitic SUS304, 316 and precipitation-hardening SUS630, 631 are preferred from the viewpoint of durability at high temperatures.

[0027] As shown in Figure 1, the other end of the stem 20 is an open end of a hollow section, and the hollow section of the stem 20 is in communication with the flow path 12b of the connecting member 12. In the pressure sensor 10, the fluid introduced into the flow path 12b is guided from the hollow section of the stem 20 to the inner surface 22a, which is the other surface of the membrane 22, and the fluid pressure acts on the membrane 22.

[0028] A flange portion 21 is formed around the open end of the stem 20 so as to protrude outward from the axis of the stem 20. The flange portion 21 is sandwiched between the connecting member 12 and the retaining member 14, sealing the flow path 12b leading to the inner surface 22a of the membrane 22.

[0029] The connecting member 12 has a screw groove 12a for fixing the pressure sensor 10. The pressure sensor 10 is fixed to a pressure chamber containing the fluid to be measured via the screw groove 12a. As a result, the flow path 12b formed inside the connecting member 12 and the inner surface 22a of the membrane 22 in the stem 20 are in airtight communication with the pressure chamber containing the fluid to be measured.

[0030] A circuit board 16 is attached to the upper surface of the retaining member 14. The circuit board 16 has a ring-shaped form that surrounds the stem 20, but the shape of the circuit board 16 is not limited to this. The circuit board 16 incorporates, for example, a circuit that transmits detection signals from the sensor member 18.

[0031] As shown in Figure 1, a sensor member 18 is formed on the end face of the stem 20. Figure 2 is a plan view of the end face portion of the stem 20 shown in Figure 1, viewed from above. As shown in Figure 2, the sensor member 18 has a protective film 40 and an electrode portion 50 exposed from the protective film 40. The sensor member 18 also has a protected portion 30 that is protected from the external environment by the protective film 40. The protected portion 30 is located below the protective film 40 and the electrode portion 50. As will be described later, the protected portion 30 has a detection portion 33 that detects pressure.

[0032] As shown in Figure 1, the electrode section 50 and the circuit board 16 are connected by intermediate wiring 72, such as wire bonding. Note that the intermediate wiring 72 is not shown in Figure 2.

[0033] Figure 3 is a cross-sectional view of the sensor member 18 along the cross-sectional line III-III shown in Figure 2. The sensor member 18 will be described below, mainly using Figures 2 and 3.

[0034] As shown in Figure 3, in the sensor member 18, the protected portion 30 having the detection unit 33 (see Figure 2) is provided on the outer surface 22b, which is one surface of the membrane 22, which is a metal substrate. The protected portion 30 is positioned between the membrane 22 and the protective film 40, shielded from fluids below by the membrane 22, and protected from the external environment in which the sensor member 18 is provided by the protective film 40 above.

[0035] As shown in Figure 3, the protected portion 30 has an insulating film 38 and a strain-resistant film 32. The insulating film 38 covers the outer surface 22b of the membrane 22, which is a metal substrate, from above. The insulating film 38 is also located between the lower membrane 22 and the upper strain-resistant film 32, ensuring electrical insulation between the membrane 22 and the strain-resistant film 32.

[0036] Although not shown in Figure 2, the insulating film 38 is formed to cover almost the entire outer surface 22b of the membrane 22. The insulating film 38 is composed of an insulating film such as silicon oxide, silicon nitride, or silicon oxynitride. The thickness of the insulating film 38 is preferably 10 μm or less, and more preferably 1 to 5 μm. The insulating film 38 can be formed on the outer surface 22b of the membrane 22 by a vapor deposition method such as CVD.

[0037] As shown in Figure 3, the strain resistance film 32 is formed on the insulating film 38 and constitutes the detection unit 33 shown in Figure 2. As shown in Figure 2, the strain resistance film 32 has a first resistor R1, a second resistor R2, a third resistor R3, and a fourth resistor R4 formed in a predetermined pattern. The first to fourth resistors R1, R2, R3, and R4 generate strain in accordance with the deformation of the membrane 22, and their resistance values ​​change in accordance with the deformation of the membrane 22. These first to fourth resistors R1 to R4 are connected by electrical wiring 34 also formed on the strain resistance film 32 to constitute a Wheatstone bridge circuit as the detection unit 33.

[0038] Furthermore, since the amount of deformation of the membrane 22 detected by the detection unit 33 changes depending on the pressure of the fluid acting on the membrane 22, the detection unit 33 can detect the fluid pressure, which is the pressure of the fluid acting on the membrane 22, which is a metal member. In other words, the first to fourth resistors R1 to R4 of the sensor member 18 shown in Figure 2 are provided at positions where the membrane 22 shown in Figures 1 and 2 deforms and distorts due to the fluid pressure, and are configured so that the resistance value changes according to the amount of distortion. The pressure sensor 10 shown in Figure 1 can receive the output of the detection unit 33 in the sensor member 18 and supply power to the sensor member 18 from the power supply unit via the circuit board 16.

[0039] The strain resistance film 32 having the first to fourth resistors R1 to R4 shown in Figure 2 can be fabricated, for example, by patterning a conductive thin film of a predetermined material. The strain resistance film 32 contains, for example, Cr and Al, preferably 50 to 99 at% Cr and 1 to 50 at% Al, and more preferably 70 to 90 at% Cr and 5 to 30 at% Al. By including Cr and Al in the strain resistance film 32, the TCR (Temperature coefficient of Resistance) and TCS (Temperature coefficient of Sensitivity) are stabilized in high-temperature environments, enabling highly accurate pressure detection. Furthermore, by setting the Cr and Al content within a predetermined range, a high gauge factor and good temperature stability can be achieved at a higher level.

[0040] The strain resistance film 32 may contain elements other than Cr and Al; for example, the strain resistance film 32 may contain O and N. The O and N contained in the strain resistance film 32 may be those that remained in the reaction chamber during the deposition of the strain resistance film 32 and were incorporated into the strain resistance film 32. Alternatively, the O and N contained in the strain resistance film 32 may be intentionally introduced into the strain resistance film 32, for example, by being used as an atmospheric gas during deposition or annealing.

[0041] Furthermore, the strain resistance film 32 may contain metallic elements other than Cr and Al. The strain resistance film 32 may contain trace amounts of metallic and nonmetallic elements other than Cr and Al, and its gauge factor and temperature characteristics may be improved by heat treatment such as annealing. Examples of metallic and nonmetallic elements other than Cr and Al that can be included in the strain resistance film 32 include Ti, Nb, Ta, Ni, Zr, Hf, Si, Ge, C, P, Se, Te, Zn, Cu, Bi, Fe, Mo, W, As, Sn, Sb, Pb, B, Ge, In, Tl, Ru, Rh, Re, Os, Ir, Pt, Pd, Ag, Au, Co, Be, Mg, Ca, Sr, Ba, Mn, and rare earth elements.

[0042] The strain resistance film 32 can be formed by thin-film methods such as sputtering or vapor deposition. The first to fourth resistors R1 to R4 can be formed, for example, by patterning a thin film into a meander shape. The thickness of the strain resistance film 32 is not particularly limited, but is preferably 10 μm or less, and more preferably 0.1 to 1 μm. The electrical wiring 34 is formed by patterning the strain resistance film 32, as shown in Figure 3. However, the electrical wiring 34 can also be formed by a conductive film or layer different from the strain resistance film 32.

[0043] As shown in Figure 3, the protective film 40 is formed on the protected part 30 and covers at least a portion of the protected part 30 from above. As shown in Figures 2 and 3, the protective film 40 has an opening 48 in which the electrode part 50 is formed. As shown in Figure 2, the protective film 40 is formed to cover the entire upper surface of the strain resistance film 32 of the protected part 30, except for the portion in which the opening 48 is formed. In Figure 2, to explain the arrangement of the protective film 40, the protective film 40 is hatched with diagonal lines, and the shape of the detection part 33 etc. formed on the protected part 30 below the protective film 40 is shown with dotted lines by looking through the protective film 40.

[0044] As shown in Figure 3, the protective film 40 has a first protective film portion 42 having a first thickness T1 and a second protective film portion 44 having a second thickness T2 that is thicker than the first thickness T1. The second protective film portion 44 is formed on the opening periphery 48a of the opening 48 leading to the protected part 30. The first protective film portion 42 is formed on the part of the opening 48 other than the opening periphery 48a where the second protective film portion 44 is formed. In other words, the thickness of the protective film 40 around the opening 48 (second thickness T2) is thicker than the thickness of the other parts away from the opening 48 (first thickness T1).

[0045] The second protective film portion 44 is formed, for example, in a region within approximately 10 μm of the outer edge of the opening 48. The first protective film portion 42 is formed, for example, in a region approximately 10 μm or more away from the outer edge of the opening 48. The first thickness T1 and the second thickness T2 are the average thickness of the first protective film portion 42 and the second protective film portion 44, and the film thicknesses of the first protective film portion 42 and the second protective film portion 44 do not necessarily have to be constant.

[0046] The first thickness T1 of the first protective film portion 42 in the protective film 40 can be, for example, 10 to 1000 nm, preferably about 100 to 300 nm. The second thickness T2 of the second protective film portion 44 in the protective film 40 can be, for example, 101 to 300%, preferably about 106 to 150%, of the first thickness T1. By making the second thickness T2 thicker than the first thickness T1, the distance over which the interface 60 between the protective film 40 and the electrode portion 50 shields the protected portion 30 can be increased. However, if the second thickness T2 is too thick, there is a problem that it takes too long to form the protective film 40.

[0047] The protective film 40 is composed of an insulating film, similar to the insulating film 38. Examples of insulating films constituting the protective film 40 include oxides, nitrides, and oxynitrides, and these films are preferred from the viewpoint of improving the strength of the protective film 40. More specifically, examples of materials constituting the protective film 40 include SiO2, SiON, Si3N4, AlO3, and ZrO2.

[0048] The protective film 40 can be formed on the strain-resistant film 32, which is part of the protected portion 30, by methods such as vapor deposition (CVD) or sputtering, but the method of forming the protective film 40 is not particularly limited.

[0049] As shown in Figures 2 and 3, the electrode portion 50 is formed in the opening 48 of the protective film 40 and on the peripheral edge 48a of the opening 48. As shown in Figure 2, the sensor member 18 has electrode portions 50 formed in four locations corresponding to the opening 48 of the protective film 40. However, the number and arrangement of electrode portions 50 on the sensor member 18 are not limited to the example shown in Figure 2.

[0050] As shown in Figure 3, the electrode portion 50 has a first electrode portion 52 positioned in the opening 48 and connected to the strain resistance film 32 of the protected portion 30, and a second electrode portion 54 connected to the first electrode portion 52 at its outer peripheral edge 52a and formed on the second protective film portion 44.

[0051] The first electrode portion 52 is the part of the electrode portion 50 that is positioned inside the opening periphery 48a of the protective film 40 when the sensor member 18 is viewed from above. The lower part of the first electrode portion 52 is positioned inside the opening 48, which is a region inside the opening periphery 48a and lower than the upper end of the second protective film portion 44, and the lower end of the first electrode portion 52 is in contact with the strain resistance film 32. The upper part of the first electrode portion 52 is positioned in a region higher than the upper end of the second protective film portion 44 and is connected to the second electrode portion 54.

[0052] The second electrode portion 54 is the part of the electrode portion 50 that is positioned outside the outer edge of the opening 48 when the sensor member 18 is viewed from above. As shown in Figure 3, the second electrode portion 54 is provided on the second protective film portion 44 and is connected to the first electrode portion 52 positioned in the opening 48 on the inside.

[0053] As shown in Figure 3, the interface 60 between the electrode portion 50 and the protective film 40 (second protective film portion 44) is formed between the outer peripheral edge 52a of the first electrode portion 52 and the inner wall of the opening 48, and between the lower end surface of the second electrode portion 54 and the upper end surface of the second protective film portion 44. Therefore, the interface 60 between the electrode portion 50 and the protective film 40 extends from the inner edge 60b facing the protected portion 30 to the outer peripheral edge 60a of the upper surface of the sensor member 18.

[0054] As shown in Figure 3, the outer electrode surface 50a of the electrode portion 50 that does not face the protective film 40 and the outer protective film surface 40a of the protective film 40 that does not face the electrode portion 50 are connected at the outer peripheral edge 60a of the interface 60 without forming a step. Because no step is formed at the outer peripheral edge 60a of the interface 60 and the outer electrode surface 50a and the outer protective film surface 40a are smoothly connected, the sensor member 18 can more effectively prevent moisture from accumulating at the outer peripheral edge 60a of the interface 60 and prevent moisture from entering the protected portion 30 from the interface 60.

[0055] As shown in Figure 3, in the sensor member 18, when viewed from above, the outer edge 54a of the second electrode portion 54, which is also the outer edge of the electrode portion 50, coincides with the outer edge 44a of the second protective film portion 44. In such a sensor member 18, the thickness of the protective film 40 becomes thinner at the position that coincides with the outer edge of the electrode portion 50, thus preventing the formation of depressions or other features on the outer edge 60a of the interface 60 where moisture and other substances tend to accumulate.

[0056] The electrode portion 50 is composed of a conductive film such as a metal, but the electrode portion 50 may contain any of Au, Ag, Cu, or Pd. Such an electrode portion 50 is relatively soft and can improve adhesion with the protective film 40. Furthermore, since such an electrode portion 50 is chemically stable, it contributes to improving the reliability of the sensor member 18.

[0057] The thickness of the electrode portion 50 can be, for example, 50 to 500 nm, and preferably 100 to 300 nm. Such an electrode portion 50 can be formed, for example, by a thin-film method such as sputtering or vapor deposition.

[0058] The sensor component 18 shown in Figure 3, etc., can be manufactured by, for example, the following manufacturing method. First, an insulating film 38 is formed on the outer surface 22b of the membrane 22, which is a metal substrate, to a predetermined thickness. Next, a strain resistance film 32 is formed on the upper surface of the insulating film 38. The strain resistance film 32 is formed by a thin-film method such as vapor deposition or sputtering. The shape of the strain resistance film 32, which has the first to fourth resistors R1 to R4 and electrical wiring 34 shown in Figure 2, is formed by patterning using photolithography or the like.

[0059] Next, a protective film 40 is formed to cover the strain resistance film 32 from above. As shown in Figure 3, the protective film 40 has openings 48 that expose a portion of the strain resistance film 32. The protective film 40 is also formed by thin-film methods such as CVD, vapor deposition, or sputtering. Alternatively, a protective film 40 with openings 48 can be formed by methods such as lift-off or etching.

[0060] Furthermore, a metal film is deposited on top of the strain resistance film 32 and the protective film 40 by a thin-film method, and then the electrode portion 50 is formed by shaping the outer edge of the metal film. Before or in conjunction with the formation of the electrode portion 50, the protective film 40 is formed with a thicker second protective film portion 44 on the opening periphery 48a, as shown in Figure 3. Through these steps, the sensor member 18 is obtained. The shapes of the first protective film portion 42, the second protective film portion 44, and the electrode portion 50 shown in Figures 2 and 3 can be formed, for example, by lift-off or etching.

[0061] As explained using Figures 1 to 3, since the sensor member 18 has an electrode portion 50 formed on a protective film 40, the area of ​​the opening 48 formed in the protective film 40 can be made smaller than the exposed area of ​​the electrode portion 50 when viewed from above. In addition, the protective film 40 has a thicker second protective film portion 44 around the opening 48 for the electrode portion 50 to connect to the protected portion 30. With a sensor member 18 having such a structure, the distance over which the interface 60 between the protective film 40 formed around the opening 48 and the electrode portion 50 shields the protected portion 30 is long, so the problem of moisture and other substances entering through the interface 60 can be effectively prevented.

[0062] It should be noted that the sensor member 18 described in Figures 1 to 3 is merely one embodiment of the present invention, and it goes without saying that the technical scope of the present invention includes many other embodiments and modifications. For example, the detection unit 33 of the sensor member 18 detects the pressure acting on the membrane 22 as a metal substrate, but the detection unit 33 is not limited to detecting pressure, and may also detect other physical quantities other than pressure, such as strain, acceleration, torque, or incline. By using such a sensor member, it is possible to configure physical quantity sensors other than pressure sensors.

[0063] Furthermore, an adhesion layer may be formed at the interface 60 between the electrode portion 50 and the protective film 40. Examples of adhesion layers include films containing Cr, Ti, Ni, Mo, etc., and the film thickness can be, for example, 1 to 50 nm, preferably about 5 to 20 nm. By providing an adhesion layer, the adhesion between the electrode portion 50 and the protective film 40 at the interface 60 can be improved, and the intrusion of moisture and other substances from the interface 60 can be more effectively prevented. In addition, since Cr, Ti, Ni, Mo, etc. readily form alloys with other metals, the adhesion strength between the films can be effectively increased.

[0064] Figure 4 is a cross-sectional view of the area around the electrode portion 150 in a modified sensor member 118. The sensor member 118 differs from the sensor member 18 shown in Figure 3 in that the protective film 140 has a third protective film portion 146 and the outer electrode surface 150a of the electrode portion 150 has a slope, but other parts are the same as the sensor member 18. The sensor member 118 will be explained focusing on the differences from the sensor member 18, and the similarities with the sensor member 18 will not be explained.

[0065] The sensor member 118 has a membrane 22 similar to the sensor member 18 shown in Figures 1 to 3, and a protected portion 30 having a detection portion 33. The protective film 140 of the sensor member 118 has a first protective film portion 142 having a first thickness T1, and a second protective film portion 144 having a second thickness T2 and formed on the opening periphery 48a of the opening 48 leading to the protected portion 30, similar to the protective film 40 shown in Figure 3. The protective film 140 shown in Figure 4 covers the upper surface of the strain resistance film 32 except for the portion where the opening 48 is formed.

[0066] As shown in Figure 3, the protective film 140 has a third protective film portion 146 that connects the first protective film portion 142 and the second protective film portion 144. The thickness of the third protective film portion 146 changes in a transitional manner, from a first thickness T1 at the first connection position 146a with the first protective film portion 142 to a second thickness T2 at the second connection position 146b with the second protective film portion 144.

[0067] In the sensor member 118, the second protective film portion 144 is formed on the peripheral edge 48a of the opening 48 leading to the protected portion 30. The third protective film portion 146 is formed to surround the outer circumference of the second protective film portion 144, and the first protective film portion 142 is formed on the peripheral edge 48a of the opening where the second protective film portion 144 is formed, and on the surrounding area other than the area where the third protective film portion 146 is formed.

[0068] The electrode portion 150 of the sensor member 118, similar to the electrode portion 50 shown in Figure 3, has a first electrode portion 52 positioned in the opening 48 and connected to the strain resistance film 32 of the protected portion 30, and a second electrode portion 154 connected to the first electrode portion 52 at its outer peripheral edge and formed on the second protective film portion 144. The outer peripheral edge of the second electrode portion 154, which is also the outer peripheral edge of the electrode portion 150, coincides with the outer peripheral edge of the second protective film portion 144.

[0069] The interface 160 between the electrode portion 150 and the protective film 140 extends from the inner edge 160b facing the protected portion 30 to the outer peripheral edge 160a of the upper surface of the sensor member 118. As shown in Figure 4, the outer electrode surface 150a of the electrode portion 150, which is the surface that does not face the protective film 140, and the outer protective film surface 140a of the protective film 140, which is the surface that does not face the electrode portion 150, are connected at the outer peripheral edge 160a of the interface 160 without forming a step parallel to the interface 160 inside the outer peripheral edge 160a.

[0070] Furthermore, the outer protective film surface 140a of the protective film 140 is inclined by the third protective film portion 146 near the outer peripheral edge 160a of the interface 160. The outer electrode surface 150a of the electrode portion 150 is also inclined near the outer peripheral edge 160a of the interface 160. As a result, in the sensor member 118, similar to the sensor member 18, the outer electrode surface 150a and the outer protective film surface 140a are smoothly connected. The difference in inclination between the outer electrode surface 150a and the outer protective film surface 140a around the interface 160 is not particularly limited, but for example, a value of 0 to 45 degrees is preferable from the viewpoint of preventing the intrusion of moisture, etc., from the interface 160.

[0071] The sensor member 118 shown in Figure 4 has a protective film 140 with a smoothly changing thickness, which more effectively prevents crack formation due to stress concentration in the protective film 140 and improves reliability. Furthermore, the sensor member 118 has the same effects as the sensor member 18 in terms of its common features. [Explanation of symbols]

[0072] 10…Pressure sensor 12…Connecting member 12a... Screw groove 12b...flow channel 14…Retaining member 16…Circuit board 18, 118… Sensor components 72...Intermediate wiring 20... Stem 21…Flange section 22...Membrane (metal substrate) 22a...Inner surface 22b…External surface 30…Protected part 32…Distortion Resistive Film 33...Detection unit R1...First resistor R2…Second resistor R3…Third resistor R4...4th resistor 34…Electrical wiring 38…Insulating film 40, 140...protective film 40a, 140a...Outer protective film surface 42, 142...first protective film part T1…First thickness 44, 144...Second protective film part T2...Second thickness 44a...Outer edge 146...Third protective film part 146a...First connection point 146b...Second connection point 48…Aperture 48a... Periphery of the opening 50, 150...electrode part 50a, 150a...Outer electrode surface 52...First electrode part 52a...Outer edge 54, 154...Second electrode part 54a...Outer edge 60, 160…interface 60a, 160a... outer edge 60b, 160b…Inner edge

Claims

1. A protected part having a detection unit is provided on one side of a metal substrate, A protective film having a first protective film portion having a first thickness, and a second protective film portion having a second thickness greater than the first thickness and formed on the periphery of the opening leading to the protected portion, the protective film covering at least a part of the protected portion from above, A sensor member having an electrode portion having a first electrode portion positioned in the opening and connected to the protected portion, and a second electrode portion connected to the first electrode portion at the outer peripheral edge of the first electrode portion and formed on the second protective film portion.

2. The sensor member according to claim 1, wherein the outer electrode surface in the electrode portion that does not face the protective film and the outer protective film surface in the protective film that does not face the electrode portion are connected without forming a step at the outer edge of the interface between the electrode portion and the protective film.

3. The sensor member according to claim 1, wherein, when viewed from above, the outer edge of the second electrode portion, which is also the outer edge of the electrode portion, coincides with the outer edge of the second protective film portion.

4. The sensor member according to claim 1, wherein the protective film has a thickness that changes in a transitional manner from a first thickness at the connection position with the first protective film portion to a second thickness at the connection position with the second protective film portion, and has a third protective film portion that connects the first protective film portion and the second protective film portion.

5. The sensor member according to claim 1, wherein the electrode portion includes any of Au, Ag, Cu, and Pd.

6. The sensor member according to claim 1, wherein the protective film is made of an oxide, a nitride, or an oxynitride.

7. The sensor member according to claim 1, wherein an adhesion layer is formed at the interface between the electrode portion and the protective film.

8. The sensor member according to claim 1, wherein the protected portion comprises an insulating film that covers one of the surfaces from above, and a strain resistance film formed on the insulating film and constituting the detection portion.

9. The sensor member according to claim 1, wherein the detection unit detects the pressure acting on the metal substrate.

10. A sensor member according to any one of claims 1 to 9, A physical quantity sensor having a circuit board having a circuit to which a detection signal from the detection unit is transmitted.