JP2023125776A - Temperature sensor, strain sensor, and pressure sensor - Google Patents

Abstract

To provide a temperature sensor which offers high flexibility in placement of a temperature sensitive layer and highly sensitive temperature detection, and to provide a strain sensor comprising the temperature sensor, and a pressure sensor comprising the strain sensor.SOLUTION: A pressure sensor 10 is provided, comprising an insulting layer 50 covering a membrane 22, a temperature sensitive layer 40 formed on the insulating layer 50 and configured to sense temperature, and a low adhesion layer 60 provided between the membrane 22 and the insulating layer 50 and configured to be less adhesive to the insulating layer 50 than to the membrane 22.SELECTED DRAWING: Figure 3

Description

The present invention relates to a temperature sensor, a strain sensor having the temperature sensor, and a pressure sensor having the strain sensor.

In recent years, various techniques have been proposed for pressure sensors that can simultaneously detect temperature and strain (or pressure). For example, the pressure sensor (temperature-sensitive strain composite sensor) described in Patent Document 1 is a sensor made of a material (Cr-Ni alloy) that has a strain sensitivity of 2 or more and a temperature sensitivity of within ±2000 ppm/K. It has a strained layer and a temperature sensitive layer made of a material (Fe--Pd alloy) having a temperature sensitivity of 2000 ppm/K or more and a strain sensitivity of 5 or less.

In the pressure sensor described in Patent Document 1, it is possible to suppress resistance changes in the strain-sensitive layer due to temperature fluctuations, and it is possible to prevent strain amount measurement errors from occurring in the strain-sensitive layer. Furthermore, it is possible to suppress resistance changes in the temperature sensitive layer due to strain fluctuations, and it is possible to prevent temperature measurement errors from occurring in the temperature sensitive layer.

By the way, in order to detect the temperature of the measurement target with high sensitivity in the temperature-sensitive layer, the temperature-sensitive layer is placed around the outer periphery of the base material, where the strain fluctuations are small, so that the temperature-sensitive layer is not affected by strain fluctuations in the base material. need to be placed. However, in this case, there is a problem that there is a low degree of freedom in arranging the temperature-sensitive layer because there are restrictions on the area in which the temperature-sensitive layer can be arranged. Furthermore, even if a temperature-sensitive layer is placed around the outer periphery of the base material, it is not possible to completely eliminate the effects of strain fluctuations in the base material, making it difficult to detect temperature with high sensitivity in the temperature-sensitive layer. be.

Japanese Patent Application Publication No. 2011-117971

The present invention has been made in view of the above problems, and its purpose is to provide a temperature sensor that has a high degree of freedom in arranging a temperature-sensitive layer and that can perform highly sensitive temperature detection, and a strain relief device equipped with the temperature sensor. An object of the present invention is to provide a sensor and a pressure sensor having the strain sensor.

In order to achieve the above object, the temperature sensor according to the present invention includes:
an insulating layer covering the base material;
a temperature-sensitive layer formed on the insulating layer and capable of detecting temperature;
The low adhesion layer is interposed between the base material and the insulating layer, and the insulating layer is less likely to adhere to the base material.

In the temperature sensor according to the present invention, a low adhesion layer is interposed between the base material and the insulating layer, to which the insulating layer is less likely to adhere compared to the base material. Therefore, the insulating layer formed on the low adhesion layer adheres (adheres) relatively weakly to the low adhesion layer. Therefore, in the region where the low adhesion layer is formed (low adhesion region), the strain (stress) generated in the base material propagates from the base material (or the low adhesion layer formed on it) to the insulating layer. The temperature-sensitive layer formed on the insulating layer is not easily affected by strain. This makes it possible to suppress resistance changes in the temperature-sensitive layer due to strain fluctuations, making it possible to detect the temperature of the measurement target with high sensitivity.

In addition, as long as the temperature-sensitive layer exists at a position corresponding to the low adhesion layer, the effect of strain will not significantly affect the temperature-sensitive layer. There is no need to place a temperature-sensitive layer on the outer periphery, etc. That is, in the temperature sensor according to the present invention, it is possible to arrange the temperature-sensitive layer at any position on the base material, and the degree of freedom in arrangement of the temperature-sensitive layer can be increased.

Preferably, the insulating layer is removably formed on the surface of the low adhesion layer. In such a configuration, the adhesion strength (adhesion strength) between the low adhesion layer and the insulating layer becomes extremely low, and strain (stress) tends to be attenuated at the interface between them. As a result, in the low adhesion region, the amount of strain propagated from the base material (or the low adhesion layer formed thereon) to the insulating layer is significantly reduced, and the strain does not affect the temperature sensitive layer. can be effectively prevented.

Preferably, the peel strength between the low adhesion layer and the insulating layer is lower than the peel strength between the substrate and the insulating layer. With such a configuration, for example, when a low adhesion layer is not interposed between the base material and the insulating layer, in other words, an insulating layer is formed on the base material, and then the insulating layer is further formed on the insulating layer. Compared to the case where a temperature-sensitive layer is formed, it is possible to reliably reduce the amount of strain propagated from the base material to the insulating layer, and the above-mentioned effects can be effectively obtained.

Preferably, the ionization tendency of the elements constituting the low adhesion layer is smaller than the ionization tendency of the elements constituting the base material. A low adhesion layer made of such an element has a property that it is difficult to attach an insulating layer to its surface (compared to a base material). Therefore, the adhesion strength between the low adhesion layer and the insulating layer is further reduced, effectively reducing the amount of strain propagated from the base material (or the low adhesion layer formed on it) to the insulating layer. can do.

Preferably, the low adhesion layer comprises gold, a platinum group element, or an alloy thereof. A low adhesion layer made of such an element has a property that it is difficult to attach an insulating layer to its surface (hard to chemically bond it). Therefore, by having the above configuration, the above-described effects can be effectively obtained.

In order to achieve the above object, the strain sensor (temperature-sensitive strain composite sensor) according to the present invention has the following features:
A temperature sensor according to any of the above,
a strain-sensitive layer formed on the insulating layer and capable of detecting deformation of the base material,
The strain sensitive layer is located at a different position from the low adhesion region where the low adhesion layer is formed.

As mentioned above, the insulating layer formed on the low adhesion layer adheres (adheres) relatively weakly to the low adhesion layer. (low adhesion layer) to the insulating layer. This point is advantageous for the temperature-sensitive layer in that the influence of strain can be avoided. On the other hand, the purpose of the strain-sensitive layer is to detect strain occurring in the base material with high sensitivity. It needs to be propagated without loss. In this regard, in the strain sensor according to the present invention, the strain-sensitive layer is located at a position different from the low-adhesion region where the low-adhesion layer is formed, so that the strain propagation is inhibited between the base material and the insulating layer. There are no contributing factors (i.e., low adhesion layer). Therefore, strain is propagated from the base material to the insulating layer and further from the insulating layer to the strain-sensitive layer without loss, and the strain generated in the base material in the strain-sensitive layer can be detected with high sensitivity.

In addition, in the strain sensor according to the present invention, since highly sensitive temperature detection is possible in the temperature-sensitive layer, it is possible to detect the strain detected in the strain-sensitive layer based on the accurate temperature detection value detected in the temperature-sensitive layer. The detected value can be corrected with high accuracy. This makes it possible to eliminate resistance changes in the strain-sensitive layer due to temperature fluctuations with high precision, and to identify strain occurring in the base material with high precision.

Preferably, the temperature-sensitive layer and the strain-sensitive layer are made of the same material. With such a configuration, strain detection and temperature detection can be accurately performed using one type of material. Therefore, compared to the case where these are made of different materials, it is possible to simplify the manufacturing process (for example, calibrating the resistance change of the temperature-sensitive layer and the strain-sensitive layer), improve productivity and reduce manufacturing costs. It is possible to reduce the

Preferably, at least one of the temperature-sensitive layer and the strain-sensitive layer is represented by the general formula Cr _100-xy Al _x N _y , and the composition ratios x and y are 5<x≦50, 0.1≦y≦ It is made of 20 materials. With this configuration, strain detection and temperature detection can be performed with high precision from a low temperature range of -50°C to a high temperature range of 450°C.

The temperature-sensitive layer may be arranged closer to the strain-sensitive layer than the outer periphery of the base material. Although a relatively large strain occurs near the strain-sensitive layer, as long as the temperature-sensitive layer is located at a position corresponding to the low adhesion layer, the strain is not significantly propagated to the temperature-sensitive layer. Therefore, even in the case of the above-mentioned configuration, in the low adhesion region, the influence of strain does not significantly affect the temperature sensitive layer, and highly sensitive temperature detection can be performed in the temperature sensitive layer. Moreover, since it is possible to arrange the temperature-sensitive layer at the center of the base material instead of near the outer periphery of the base material, the degree of freedom in the arrangement of the temperature-sensitive layer can be increased.

In order to achieve the above object, a pressure sensor (temperature-pressure sensor) according to the present invention includes any of the strain sensors described above. Therefore, the pressure of the measurement target can be detected with high precision based on the detected strain value detected by the strain sensor (the detected strain value that has been temperature-corrected based on the accurate detected temperature value).

FIG. 1 is a schematic cross-sectional view of a pressure sensor according to an embodiment of the present invention. FIG. 2 is a schematic plan view of the pressure sensor shown in FIG. 1. FIG. 3 is a partially enlarged cross-sectional view schematically showing the structure of the peripheral portions of the temperature-sensitive layer and strain-sensitive layer of the pressure sensor shown in FIG. 1. FIG. FIG. 4 is a schematic plan view showing a modification of the formation range of the low adhesion layer shown in FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments shown in the drawings.

As shown in FIG. 1, a pressure sensor 10 having a temperature sensor section 42 (FIG. 2) according to an embodiment of the present invention is a pressure sensor that utilizes a piezoresistive effect, and is caused by deformation of a membrane. Strain is detected by resistance change of the resistor. The pressure sensor 10 includes a connecting member 12, a restraining member 14, a substrate portion 16, and a stem 20.

The connecting member 12 is for fixing the pressure sensor 10 to a measurement target. A thread groove 12a is formed on the outer peripheral surface of the connecting member 12. The thread groove 12a is formed so that it can be screwed into a thread groove formed on the object to be measured. A flow path 12b is formed inside the connection member 12 to be used as a pressure fluid flow path. By fixing the pressure sensor 10 to the measurement target via the thread groove 12a, it is possible to airtightly communicate the flow path 12b with the pressure chamber that is the measurement target.

The restraining member 14 is for fixing the stem 20 to the connecting member 12. The restraining member 14 is arranged on the upper surface of the connecting member 12 and has a ring-shaped outer shape. A through hole is formed in the center of the restraining member 14, and the stem 20 can be inserted (arranged) inside the through hole. A part of the stem 20 (a flange portion 21 to be described later) can be fixed between the restraining member 14 and the connecting member 12.

The stem 20 has a bottomed (upper bottom) cylindrical outer shape, and is provided at one end of the flow path 12b in the connection member 12. The stem 20 is manufactured by machining a metal such as stainless steel or an alloy. The material of the stem 20 is not particularly limited as long as it causes appropriate elastic deformation.

The stem 20 has a flange portion 21, a membrane 22, and a side wall portion 23. The side wall portion 23 has a cylindrical outer shape. One end of the side wall 23 is closed with the membrane 22, while the other end of the side wall 23 is open. The flange portion 21 is provided on the opening side of the stem 20 and protrudes radially outward from the opening edge formed at the other end of the side wall portion 23. By sandwiching and fixing the flange portion 21 between the restraining member 14 and the connecting member 12, the stem 20 is connected to the connecting member 12 while the opening of the stem 20 is airtightly connected to one end of the flow path 12b of the connecting member 12. It is possible to fix it.

The membrane 22 is a part to which the pressure to be measured is transmitted, and constitutes the upper bottom part of the stem 20. The membrane 22 is preferably formed thinner than other parts of the stem 20 (such as the side wall portion 23), and is deformed (distorted) in response to the pressure transmitted from the flow path 12b (pressure received from the pressure fluid). to occur. The membrane 22 has an inner surface 22a that contacts the pressure fluid and an outer surface 22b opposite the inner surface 22a. A strain sensor section 32, a temperature sensor section 42, etc., which will be described later, are provided on the outer surface 22b of the membrane 22 (see FIG. 2).

The substrate portion 16 is fixed to the upper surface of the restraining member 14 and has a ring-shaped outer shape. A through hole is formed in the center of the substrate portion 16, and the stem 20 can be inserted (arranged) inside the through hole. An electrode section (not shown) is formed on the substrate section 16, and the electrode section on the substrate section 16 and the electrode section on the membrane 22 (electrode sections 71 to 76 shown in FIG. 2) are formed by wire bonding or the like. They are electrically connected via connection wiring 80 . The electrode portion formed on the substrate portion 16 is electrically connected to, for example, a signal line, a power supply line, or a ground.

As shown in FIG. 3, the pressure sensor 10 includes a strain-sensitive layer 30, a temperature-sensitive layer 40, an insulating layer 50, and a low adhesion layer 60. The insulating layer 50 is formed on the membrane 22 and covers the entire upper surface 22b of the membrane 22. The insulating layer 50 is for ensuring insulation between the membrane 22 and the strain-sensitive layer 30 and between the membrane 22 and the temperature-sensitive layer 40.

The insulating layer 50 is made of an inorganic insulating material such as silicon oxide (SiO ₂ ), silicon nitride (SiN), silicon oxynitride (SiO _x N _y ), or aluminum oxide (AlO _x ). The thickness of the insulating layer 50 is preferably 10 μm or less, more preferably 1 to 5 μm. The insulating layer 50 is formed on the outer surface 22b of the membrane 22 by a thin film method (vacuum method) such as vapor deposition, CVD, or sputtering.

The insulating layer 50 is formed on the surface of the membrane 22 at the position where the strain-sensitive layer 30 is formed. Furthermore, the insulating layer 50 is formed on the surface of a low adhesion layer 60 (described later) at the position where the temperature-sensitive layer 40 is formed, and is not directly formed on the outer surface 22b of the membrane 22.

The strain-sensitive layer 30 is made of a material that can detect deformation of the membrane 22, and is formed on the insulating layer 50. The strain sensitive layer 30 is formed of a strain resistance film containing, for example, Cr and Al. Since the strain-sensitive layer 30 contains Cr and Al, TCR (Temperature coefficient of Resistance) and TCS (Temperature coefficient of Sensitivity) in high temperature environments are stabilized, allowing highly accurate pressure detection. becomes possible.

The strain-sensitive layer 30 (the same applies to the temperature-sensitive layer 40) is represented by the general formula Cr _100-xy Al _x N _y , and the composition ratios x and y are 5<x≦50, 0.1≦y≦20. It is made up of a certain material. By setting the composition ratios x and y within the above ranges, it is possible to achieve both a high gauge factor and good temperature stability at a higher level. As a result, strain detection and temperature detection can be performed with high accuracy from a low temperature range of -50°C to a high temperature range of 450°C. Note that only one of the strain-sensitive layer 30 and the temperature-sensitive layer 40 may be formed of a material represented by the above general formula. The thickness of the strain-sensitive layer 30 is preferably 10 μm or less, more preferably 0.1 to 1 μm.

The strain sensitive layer 30 has a strain sensor section 32 shown in FIG. As shown in FIG. 2, the strain sensor section 32 includes sensor resistors R1 to R4. The sensor resistors R1 to R4 are pressure detecting elements, and are configured so that they generate strain according to the deformation of the membrane 22, and their resistance values change according to the amount of strain due to the piezoresistance effect. Note that the upper part of FIG. 2 shows a schematic cross-sectional view of the stem 20, and the lower part of FIG. 2 shows a schematic plan view of the stem 20.

The strain sensor section 32 is formed in a strain generation area of the membrane 22. The strain generation region of the membrane 22 consists of a first strain region 24 that produces strain characteristics in a predetermined direction, and a second strain region 26 that produces strain characteristics in the opposite direction to the first strain region 24.

The first strain region 24 of the membrane 22 receives pressure (positive pressure) from the inner surface 22a of the membrane 22 and generates strain −ε (compressive strain) in the negative direction, whereas the second strain region 24 of the membrane 22 generates strain −ε (compressive strain) in the negative direction. 26 receives pressure (positive pressure) from the inner surface 22a and generates strain +ε (tensile strain) in the positive direction. In this way, the strain characteristics on the first strain region 24 and the strain characteristics on the second strain region 26 are preferably in different directions (different signs and cancel each other out).

The first strain region 24 and the second strain region 26 are each formed concentrically around the center O of the membrane 22. The second strain region 26 is located at a predetermined distance in the radial direction from the center O of the membrane 22 and is formed in the center of the membrane 22 . The first strain region 24 is formed on the outside (outer circumferential side) of the second strain region 26 and is located a predetermined distance away from the second strain region 26 in the radial direction of the membrane 22 . The outer edge 27 of the membrane 22 is connected to the side wall 23 of the stem 20.

The sensor resistors R1 to R4 are fabricated, for example, by patterning a conductive thin film (semiconductor thin film, metal thin film, etc.) made of a predetermined material into a meander shape or the like. Patterning of the conductive thin film is performed by microfabrication using semiconductor processing techniques such as laser processing and screen printing. The conductive thin film is formed on the insulating layer 50 by a thin film method (vacuum method) such as vapor deposition, CVD, or sputtering.

The sensor resistor R1 and the sensor resistor R3 are formed in the first strain region 24 and are arranged to face each other with the center O of the membrane 22 in between. The sensor resistor R2 and the sensor resistor R4 are formed in the second strain region 26 and are arranged to face each other with the center O of the membrane 22 in between. The direction in which the sensor resistor R1 and the sensor resistor R3 face each other is approximately perpendicular to the direction in which the sensor resistor R2 and the sensor resistor R4 face each other. Note that the arrangement of the sensor resistors R1 to R4 is not limited to the arrangement shown in the drawings, and may be changed as appropriate.

The strain sensor section 32 is formed on the outer surface 22b of the membrane 22 so as to span the first strain region 24 and the second strain region 26, and has an annular (elliptic annular) outer shape. The strain sensor section 32 is a bridge circuit, and in this embodiment constitutes a Wheatstone bridge. However, the configuration of the strain sensor section 32 is not limited to the illustrated configuration, and the strain sensor section 32 may constitute another bridge circuit.

In the strain sensor section 32, the sensor resistor R1 and the sensor resistor R2 are electrically and physically connected to an electrode section 71 formed on the insulating layer 50 (FIG. 3). The sensor resistor R1 and the sensor resistor R4 are electrically and physically connected to an electrode section 72 formed on the insulating layer 50. Sensor resistor R3 and sensor resistor R4 are electrically and physically connected to electrode section 73 formed on insulating layer 50. The sensor resistor R2 and the sensor resistor R3 are electrically and physically connected to an electrode section 74 formed on the insulating layer 50. The electrode parts 71 to 74 are electrically connected to an electrode part (not shown) formed on the substrate part 16 by wire bonding or the like.

The electrode portions 71 to 74 are fabricated, for example, by patterning a conductive thin film (semiconductor thin film, metal thin film, etc.) made of a predetermined material into a predetermined shape by the same method as the sensor resistors R1 to R4. Note that the electrode parts 71 to 74 are continuously connected to the sensor resistors R1 to R4, and are made of the same conductive thin film.

As shown in FIG. 3, the temperature-sensitive layer 40 is made of a temperature-detectable material and is formed on the insulating layer 50. The temperature sensitive layer 40 is preferably made of the same material as the strain sensitive layer 30. That is, the temperature sensitivity (resistance temperature coefficient) of the temperature sensitive layer 40 is preferably equal to the temperature sensitivity of the strain sensitive layer 30, and the strain sensitivity (gauge factor) of the temperature sensitive layer 40 is preferably equal to the strain sensitivity of the strain sensitive layer 30. By accurately detecting strain and temperature using one type of material, the manufacturing process (for example, resistance change of the temperature-sensitive layer 40 and strain-sensitive layer 30 This makes it possible to simplify the calibration process, thereby improving productivity and reducing manufacturing costs. The thickness of the temperature sensitive layer 40 is preferably 10 μm or less, more preferably 0.1 to 1 μm.

The temperature sensitive layer 40 has a temperature sensor section 42 shown in FIG. Although not particularly limited, in the example shown in FIG. 2, the temperature sensor section 42 is formed independently of the strain sensor section 32 (without being electrically connected to it). It is preferable that the temperature sensor section 42 is formed at the outer edge 27 of the membrane 22, which is relatively less susceptible to distortion of the membrane 22. That is, the temperature sensor section 42 (temperature sensitive layer 40) is preferably disposed closer to the outer periphery of the membrane 22 than the strain sensor section 32 (strain sensitive layer 30).

However, the temperature sensor section 42 may be arranged at any position between the first strain region 24 and the outer edge section 27. Although the temperature sensor section 42 extends along the outer circumferential direction of the membrane 22 at the outer edge 27 of the membrane 22, the direction in which the temperature sensor section 42 extends is not limited to this. For example, the temperature sensor section 42 may extend radially along the radial direction of the membrane 22.

The temperature sensor section 42 includes a correction resistor RT. In the example shown in FIG. 2, the temperature sensor section 42 includes one correction resistor RT, but may include a plurality of correction resistors RT. The correction resistor RT is a temperature detection element, and changes its resistance value depending on, for example, a change in the temperature of the pressure fluid. By equipping the pressure sensor 10 with the correction resistor RT, the error (temperature It becomes possible to correct the resistance changes of the sensor resistors R1 to R4 caused by fluctuations.

The correction resistor RT is manufactured, for example, by patterning a conductive thin film (semiconductor thin film, metal thin film, etc.) made of a predetermined material into a meander shape or the like. Patterning of the conductive thin film is performed by microfabrication using semiconductor processing techniques such as laser processing and screen printing. The conductive thin film is formed on the insulating layer 50 by a thin film method (vacuum method) such as vapor deposition, CVD, or sputtering.

One end of the correction resistor RT is electrically and physically connected to an electrode portion 75 formed on the insulating layer 50 (FIG. 3), and the other end of the correction resistor RT is connected to the insulating layer 50. It is electrically and physically connected to an electrode section 76 formed on the electrode section 76 . The electrode parts 75 and 76 are electrically connected to an electrode part (not shown) formed on the substrate part 16 by wire bonding or the like.

The electrode parts 75 and 76 are fabricated, for example, by patterning a conductive thin film (semiconductor thin film, metal thin film, etc.) made of a predetermined material into a predetermined shape using a method similar to that of the correction resistor RT. Note that the electrode parts 75 and 76 are continuously connected to the correction resistor RT, and are made of the same conductive thin film.

As shown in FIG. 3, the low adhesion layer 60 is locally formed on a portion of the outer surface 22b of the membrane 22, and locally covers a portion of the outer surface 22b. The low adhesion layer 60 is formed in the membrane 22 at a position corresponding to the temperature-sensitive layer 40 and not at a position corresponding to the strain-sensitive layer 30. That is, in this embodiment, the temperature-sensitive layer 40 is located in the low-adhesion region 62 (see FIG. 2) where the low-adhesion layer 60 is formed, while the strain-sensitive layer 30 is located at a position different from the low-adhesion region 62. Located in

At the position where the temperature sensitive layer 40 is formed, the low adhesion layer 60, the insulating layer 50, and the temperature sensitive layer 40 are laminated in this order on the membrane 22. Further, at the position where the strain-sensitive layer 30 is formed, the insulating layer 50 and the strain-sensitive layer 30 are laminated in this order on the membrane 22.

The low adhesion layer 60 is interposed (sandwiched) between the outer surface 22b of the membrane 22 and the insulating layer 50. The low adhesion layer 60 has a property that the insulating layer 50 is less likely to adhere (adhere) to the outer surface 22b of the membrane 22. Therefore, the insulating layer 50 is relatively weakly adhered (adhered or adhered) to the surface of the low adhesion layer 60 and is formed on the surface of the low adhesion layer 60 so that it can be peeled off. Furthermore, although the insulating layer 50 is disposed on the surface of the low-adhesion layer 60 so as to be integrated with the low-adhesion layer 60, it is not substantially chemically bonded to the low-adhesion layer 60. For example, the insulating layer 50 may be partially in close contact with the low adhesion layer 60 or may be partially raised relative to the low adhesion layer 60.

In the low adhesion region 62, strain (stress) generated in the membrane 22 is difficult to propagate from the membrane 22 (or the low adhesion layer 60 formed thereon) to the insulating layer 50. That is, as described above, since the adhesion between the low adhesion layer 60 and the insulating layer 50 is low, the interface (low adhesion part) between the low adhesion layer 60 and the insulating layer 50 is formed on the membrane 22 (or This acts as an inhibiting factor that prevents strain from propagating from the low adhesion layer 60) to the insulating layer 50.

In this way, the present embodiment makes use of the low adhesion strength (adhesion strength) of the insulating layer 50 to the low adhesion layer 60 to prevent the temperature-sensitive layer 40 formed on the insulating layer 50 from forming on the membrane 22. This prevents the influence of distortion.

Here, the resistance value R _t of the temperature sensitive layer 40 is expressed by the following formula. However, in the following formula, TCR _t represents the temperature coefficient of resistance, TCS _t represents the temperature coefficient of sensitivity, k _t represents the gauge factor, ε represents the amount of strain, and T represents the temperature.

In this embodiment, the strain in the membrane 22 is significantly reduced at the interface between the low adhesion layer 60 and the insulating layer 50, and the amount of strain propagated to the temperature sensitive layer 40 is extremely small. Therefore, in the above formula, ε can be brought close to 0. Thereby, it is possible to prevent the resistance value R _t of the temperature-sensitive layer 40 from changing due to strain fluctuations in the membrane 22 (variations in ε).

On the other hand, the temperature to be measured is determined from the membrane 22 (or the low adhesion layer 60 formed thereon) to the insulating layer 50, regardless of the low adhesion between the low adhesion layer 60 and the insulating layer 50. fully propagated to. Therefore, in the temperature-sensitive layer 40, substantially only resistance changes occur due to temperature fluctuations of the object to be measured, and resistance changes due to strain fluctuations of the membrane 22 do not occur. Therefore, in the temperature sensitive layer 40, it is possible to prevent temperature measurement errors from occurring and to detect the temperature of the object to be measured with high sensitivity (high resolution).

The peel strength between the low adhesion layer 60 and the insulating layer 50 is preferably lower than the peel strength between the membrane 22 and the insulating layer 50. In this case, the insulating layer 50 will not easily peel off from the surface of the membrane 22 in areas other than the low adhesion areas 62. On the other hand, the insulating layer 50 is more likely to peel off from the surface of the low adhesion layer 60 in the low adhesion region 62 compared to the membrane 22.

Therefore, the adhesion strength (adhesion strength) between the low adhesion layer 60 and the insulating layer 50 becomes extremely low, and strain (stress) tends to be significantly attenuated at these interfaces. As a result, in the low adhesion region 62, the amount of strain propagated from the membrane 22 (or the low adhesion layer 60 formed thereon) to the insulating layer 50 is significantly reduced, and the strain is applied to the temperature sensitive layer 40. It is possible to effectively prevent the influence from occurring.

The ionization tendency of the elements constituting the low adhesion layer 60 is preferably smaller than the ionization tendency of the elements constituting the membrane 22. Furthermore, the low adhesion layer 60 is preferably made of an element that is less likely to oxidize (noble metal) or less likely to corrode (rust) than the elements constituting the membrane 22. Such elements include gold (Au), silver (Ag), platinum (Pt), palladium (Pd), rhodium (Rh), iridium (Ir), ruthenium (Ru), osmium (Os) and rhenium (Re). ). Further, the low adhesion layer 60 preferably contains gold, platinum group elements (Ru, Rh, Pd, Os, Ir, Pt), or an alloy thereof. Moreover, the low adhesion layer 60 may be composed of elements other than the above-mentioned elements.

Further, the low adhesion layer 60 may be made of an organic substance. Examples of organic materials that can form the low adhesion layer 60 include pentacene, thiazolothiazole derivatives, and polythiophene derivatives that have not been surface-treated.

The low adhesion layer 60 made of such an element has a property that makes it difficult to attach the insulating layer 50 to its surface (hard to chemically bond it). Therefore, the adhesion strength between the low adhesion layer 60 and the insulating layer 50 is effectively reduced, and the strain propagated from the membrane 22 (or the low adhesion layer 60 formed thereon) to the insulating layer 50 is reduced. The amount can be effectively reduced.

The low adhesion layer 60 is produced, for example, by patterning a conductive thin film made of the above-mentioned material into a predetermined shape as necessary. Patterning of the conductive thin film is performed by microfabrication using semiconductor processing techniques such as laser processing and screen printing. The conductive thin film is formed on the outer surface 22b of the membrane 22 by a thin film method (vacuum method) such as vapor deposition, CVD, or sputtering.

As shown in FIG. 2, the low adhesion region 62 is formed on the outer edge 27 of the membrane 22, corresponding to the position of the temperature sensor section 42 (temperature sensitive layer 40). The low adhesion region 62 may be formed at any position between the first strain region 24 and the outer edge 27. However, it is preferable that the low adhesion region 62 be formed at a position that does not overlap with the strain sensor section 32 (sensor resistors R1 to R4 and electrode sections 71 to 74). This is to prevent the insulating layer 50 from peeling off at the position of the strain sensor section 32 and to ensure that the strain generated in the membrane 22 is sufficiently propagated to the strain sensitive layer 30.

As shown in FIG. 3, the temperature sensitive layer 40 (correction resistor RT) is preferably disposed inside the low adhesion layer 60 (within the low adhesion region 62). In this case, the low adhesion layer 60 is disposed at least immediately below the temperature sensitive layer 40, and the temperature sensitive layer 40 does not protrude outside the low adhesion layer 60 (outside the low adhesion region 62). Therefore, it is possible to prevent a strain propagation path from being formed outside the low adhesion region 62 from the membrane 22 to the temperature sensitive layer 40 (without passing through the low adhesion layer 60). Thereby, strain (stress) generated in the membrane 22 can be prevented from propagating from the membrane 22 to the temperature-sensitive layer 40 (without passing through the low adhesion layer 60).

The size of the low adhesion layer 60 (surface area S1) is preferably equal to or larger than the size of the temperature-sensitive layer 40 (surface area S2). The ratio S1/S2 of the surface area S1 of the low adhesion layer 60 to the surface area S2 of the temperature-sensitive layer 40 is preferably 1 or more, more preferably 2 or more. Further, the ratio S1/S3 of the surface area S1 of the low adhesion layer 60 to the surface area S3 of the outer surface 22b of the membrane 22 is preferably 1/16 to 3/4. By setting the ratio S1/S2 or S1/S3 within the above range, the low adhesion layer 60 is provided with an appropriately large surface area, and the strain (stress) generated in the membrane 22 is transferred from the membrane 22 to the temperature-sensitive layer. 40 (without passing through the low adhesion layer 60).

When the membrane 22 is viewed from above, the shape of the low adhesion layer 60 preferably corresponds to the shape of the temperature sensitive layer 40. For example, the shape of the low adhesion layer 60 may be rectangular, circular, oval, or any other shape when viewed from above the membrane 22. Moreover, when the correction resistor RT is formed in a meander shape, the low adhesion layer 60 may also be formed in a meander shape correspondingly.

As shown in FIG. 2, the extending direction of the low adhesion layer 60 (low adhesion region 62) may correspond to the extending direction of the temperature sensitive layer 40 (temperature sensor section 42). Further, the low adhesion layer 60 may extend in the outer circumferential direction of the membrane 22 at the outer edge portion 27 of the membrane 22 . In this case, the low adhesion layer 60 has an arc shape. Alternatively, the low adhesion layer 60 may be formed so as to go around the membrane 22 along the outer circumferential direction of the membrane 22. In this case, the low adhesion layer 60 has a substantially ring shape. Alternatively, the low adhesion layer 60 may extend in the radial direction of the membrane 22 between the first strained region 24 and the outer edge 27.

As shown in FIG. 3, the thickness T1 of the low adhesion layer 60 is preferably 0.001 to 1 μm, more preferably 0.001 to 0.1 μm. The thickness T1 of the low adhesion layer 60 is preferably equal to or smaller than the thickness T2 of the insulating layer 50. The ratio T1/T2 of the thickness T1 of the low adhesion layer 60 to the thickness T2 of the insulating layer 50 is preferably 1/1000 to 1/10, more preferably 1/1000 to 1/100. By setting the thickness T1 of the low adhesion layer 60 within the above range, it is possible to effectively prevent the insulating layer 50 from adhering (adhering) to the surface of the low adhesion layer 60.

In the low adhesion region 62 , the insulating layer 50 is formed to swell in a stepped manner by an amount corresponding to the thickness of the low adhesion layer 60 . However, the surface of the insulating layer 50 may be flush with the low adhesion region 62 and a region other than the low adhesion region 62 (a region adjacent to the low adhesion region 62). Further, the thickness of the insulating layer 50 in the low adhesion region 62 may be different from the thickness of the insulating layer 50 in the region other than the low adhesion region 62. For example, the thickness of the former may be smaller than the thickness of the latter.

Next, a method for manufacturing the pressure sensor 10 shown in FIG. 1 will be described. First, the stem 20 is prepared. The stem 20 is made of stainless steel such as SUS316. Next, as shown in FIG. 3, a low adhesion layer 60 is formed on the outer surface 22b of the membrane 22.

In this case, a low adhesion layer 60 is deposited to a predetermined thickness at a predetermined position on the outer surface 22b of the membrane 22 (a position corresponding to the low adhesion region 62) so as to locally cover the outer surface 22b, or by a thin film method such as CVD or sputtering. (vacuum method). The low adhesion layer 60 may be patterned if necessary. Methods for patterning include photolithography. Specifically, techniques such as lift-off, milling, and etching are used.

Next, the insulating layer 50 is formed on the outer surface 22b of the membrane 22 on which the low adhesion layer 60 is formed. In this case, the insulating layer 50 is formed to a predetermined thickness by a thin film method (vacuum method) such as vapor deposition, CVD, or sputtering so as to completely cover the outer surface 22b.

Next, the strain-sensitive layer 30 is formed at a predetermined position on the surface of the insulating layer 50. In this case, the strain-sensitive layer 30 is formed to a predetermined thickness by a thin film method (vacuum method) such as vapor deposition, CVD, or sputtering so as to locally cover the insulating layer 50. Next, the strain-sensitive layer 30 is patterned in a predetermined pattern, and sensor resistors R1 to R4 (FIG. 2), which will become the strain sensor section 32, and electrode sections 71 to 74 (FIG. 2) are formed on the strain-sensitive layer 30. do.

Further, a temperature sensitive layer 40 is formed at a predetermined position on the surface of the insulating layer 50. In this case, the temperature sensitive layer 40 is formed in the same manner as the strain sensitive layer 30 so as to locally cover the insulating layer 50 at a position corresponding to the low adhesion layer 60. Next, the temperature-sensitive layer 40 is patterned in a predetermined pattern, and a correction resistor RT (FIG. 2) that becomes the temperature sensor section 42 and electrode sections 75 and 76 (FIG. 2) are formed on the temperature-sensitive layer 40. . Note that the electrode parts 75 and 76 of the temperature sensitive layer 40 may be arranged outside the low adhesion region 62, but the correction resistor RT is arranged inside the low adhesion region 62. It is preferable. Through the above steps, the pressure sensor 10 shown in FIG. 1 can be obtained.

As explained above, in this embodiment, as shown in FIG. 3, the insulating layer 50 formed on the low adhesion layer 60 adheres (closely adheres) to the low adhesion layer 60 relatively weakly. Therefore, in the low adhesion region 62, strain generated in the membrane 22 is difficult to propagate from the membrane 22 (or the low adhesion layer 60 formed thereon) to the insulating layer 50. Therefore, in the temperature-sensitive layer 40, it is possible to avoid the influence of strain on the membrane 22, suppress changes in resistance of the temperature-sensitive layer 40 caused by strain fluctuations, and detect the temperature of the measurement target with high sensitivity. be able to.

On the other hand, since the strain-sensitive layer 30 is located at a position different from the low adhesion region 62, there is a factor that inhibits strain propagation (i.e., a low adhesion layer) between the membrane 22 and the insulating layer 50 at this position. 60) does not exist. Therefore, the strain is propagated from the membrane 22 to the insulating layer 50 and further from the insulating layer 50 to the strain-sensitive layer 30 without loss, and the strain generated in the membrane 22 in the strain-sensitive layer 30 can be detected with high sensitivity.

In addition, since the temperature sensitive layer 40 is capable of highly sensitive temperature detection, the detected strain value detected in the strain sensitive layer 30 can be determined based on the accurate temperature detected value detected by the temperature sensitive layer 40. It can be corrected with high precision. This makes it possible to eliminate changes in the resistance of the strain-sensitive layer 30 due to temperature fluctuations, and allows the strain occurring in the membrane 22 to be identified with high precision (high resolution).

In addition, as long as the temperature-sensitive layer 40 exists at a position corresponding to the low adhesion layer 60, the effect of strain will not significantly affect the temperature-sensitive layer 40. There is no need to arrange the temperature sensitive layer 40 on the top. That is, in this embodiment, it is possible to arrange the temperature-sensitive layer 40 at any position on the membrane 22, and the degree of freedom in arrangement of the temperature-sensitive layer 40 can be increased.

Note that the present invention is not limited to the embodiments described above, and can be variously modified within the scope of the present invention.

In the above embodiment, an example of application of the present invention to a pressure sensor has been described, but the present invention may be applied to equipment or elements other than pressure sensors. For example, the present invention may be applied to a strain sensor (temperature-sensitive strain composite sensor) that includes a temperature sensor (section). The strain sensor does not need to have a function (pressure calculation section) that converts the detected value of the detection signal of the strain sensor (section) into the pressure of the measurement target (fluid). Further, the present invention may be applied to a temperature sensor that does not include a strain sensor (section).

In the above embodiment, the strain sensor section 32 and the temperature sensor section 42 shown in FIG. 2 may be installed on another member (preferably a plate-shaped member) that does not include the membrane 22 (stem 20). Examples of materials constituting such a member include stainless steel (SUS), silicon, ceramic, copper alloy, aluminum alloy, steel, etc. (that is, the same material as the stem 20).

In the embodiment described above, the temperature sensor section 42 (temperature-sensitive layer 40) may be arranged on the center side of the membrane 22, as shown in FIG. In the example shown in FIG. 4, the temperature sensor section 42 is arranged closer to the strain sensor section 32 (strain-sensitive layer 30) than the outer periphery of the membrane 22. In this case, the temperature sensor section 42 may be formed in the first strain region 24 or at any position between the first strain region 24 and the second strain region 26. Further, the low adhesion region 62 may be formed in the first strain region 24 or at any position between the first strain region 24 and the second strain region 26.

Although a relatively large strain occurs in the vicinity of the strain-sensitive layer 30, as long as the temperature-sensitive layer 40 exists in a position corresponding to the low adhesion layer 60 (low-adhesion region 62), the strain will not be noticeable in the temperature-sensitive layer 40. It is never propagated. Therefore, even in the case of the above-described configuration, the strain does not significantly affect the temperature sensitive layer 40 in the low adhesion region 62, and highly sensitive temperature detection can be performed in the temperature sensitive layer 40. I can do it. Further, since it is possible to arrange the temperature-sensitive layer 40 at the center of the membrane 22 instead of near the outer edge 27 of the membrane 22, the degree of freedom in arrangement of the temperature-sensitive layer 40 can be increased.

In the above embodiment, the strain-sensitive layer 30 and the temperature-sensitive layer 40 may be formed of different materials.

DESCRIPTION OF SYMBOLS 10... Pressure sensor 12... Connection member 12a... Thread groove 12b... Channel 14... Suppressing member 16... Substrate part 20... Stem 21... Flange part 22... Membrane 22a... Inner surface 22b... Outer surface 23... Side wall part 24... First strain area 26...Second strain region 27...Outer edge portion 30...Strain sensitive layer 32...Strain sensor section 40...Temperature sensitive layer 42...Temperature sensor section 50...Insulating layer 60...Low adhesion layer 62...Low adhesion region 71-76...Electrode section 80...Connection wiring R1-R4...Sensor resistor RT...Correction resistor

Claims (10)

an insulating layer covering the base material;
a temperature-sensitive layer formed on the insulating layer and capable of detecting temperature;
A temperature sensor comprising: a low adhesion layer interposed between the base material and the insulating layer, to which the insulating layer is less likely to adhere than to the base material. The temperature sensor according to claim 1, wherein the insulating layer is releasably formed on the surface of the low adhesion layer. The temperature sensor according to claim 1 or 2, wherein the peel strength between the low adhesion layer and the insulating layer is smaller than the peel strength between the base material and the insulating layer. The temperature sensor according to claim 1, wherein the ionization tendency of the elements constituting the low adhesion layer is smaller than the ionization tendency of the elements constituting the base material. The temperature sensor according to claim 1, wherein the low adhesion layer contains gold, a platinum group element, or an alloy thereof. The temperature sensor according to any one of claims 1 to 5,
a strain-sensitive layer formed on the insulating layer and capable of detecting deformation of the base material,
In the strain sensor, the strain-sensitive layer is located at a position different from the low-adhesion region in which the low-adhesion layer is formed. The strain sensor according to claim 6, wherein the temperature sensitive layer and the strain sensitive layer are made of the same material. At least one of the temperature-sensitive layer and the strain-sensitive layer is represented by the general formula Cr _100-xy Al _x N _y , and the composition ratios x and y are 5<x≦50, 0.1≦y≦20. The strain sensor according to claim 6 or 7, wherein the strain sensor is made of a material. The strain sensor according to claim 6, wherein the temperature-sensitive layer is arranged closer to the strain-sensitive layer than to the outer periphery of the base material. A pressure sensor comprising the strain sensor according to claim 6.

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