Temperature and distortion composite sensor

Abstract

To provide a temperature-strain composite sensor which can be used in a temperature range of -50°C to 450°C, inclusive.SOLUTION: A temperature-strain composite sensor of the present invention comprises a strain-sensing resistance film represented by a general formula Cr100-x-yAlxNy, where x and y represent composition ranges that satisfy 5<x≤50 and 0.1≤y≤20, respectively, and a temperature-sensing resistance film having a temperature coefficient of resistance (TCR) greater than 2000 ppm / °C in absolute terms in a temperature range of -50°C to 450°C, inclusive.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a temperature and strain composite sensor including a temperature-sensitive resistance film and a strain-sensitive resistance film.

Background Art

[0002] As shown in Patent Document 1, a temperature and strain composite sensor that simultaneously detects the temperature and pressure of a measurement object such as a fluid is known. In particular, in Patent Document 1, by combining a strain-sensitive resistance film made of a Cr-N-based alloy and a temperature-sensitive resistance film made of an Fe-Pd alloy, it is reported that simultaneous detection of temperature and pressure is possible without the need for a Wheatstone bridge circuit for temperature compensation.

[0003] However, the gauge factor of the Cr-N-based alloy film used in Patent Document 1 extremely decreases in a high-temperature region of 200°C or higher. That is, in a high-temperature region of 200°C or higher, the accuracy of pressure measurement decreases. Therefore, the usable range of the temperature and strain composite sensor of Patent Document 1 was limited to a range of 200°C or lower. In recent years, it has been demanded to enable simultaneous detection of temperature and pressure in a range from a low-temperature region of -50°C to a high-temperature region of 450°C, and further performance improvement of the temperature and strain composite sensor has been expected.

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 circumstances, the present invention has been made, and an object thereof is to provide a temperature and strain composite sensor that can be used in a temperature range of -50°C or higher and 450°C or lower.

Means for Solving the Problems

[0006] To achieve the above object, the temperature and strain composite sensor according to the present invention is represented by the general formula Cr 100-x-y Al x N y and has a strain-sensitive resistance film in which the respective composition ranges of x and y are 5 < x ≤ 50 and 0.1 ≤ y ≤ 20, and a temperature-sensitive resistance film having an absolute value of the temperature coefficient of resistance (TCR t ) of 2000 ppm / °C or more in the temperature range of -50°C or higher and 450°C or lower.

[0007] The strain-sensitive resistance film represented by the general formula Cr 100-x-y Al x N y has a stable and high gauge factor not only in the region of 200°C or lower but also in the high-temperature region of 200°C to 450°C by satisfying 5 < x ≤ 50 and 0.1 ≤ y ≤ 20. Therefore, by using the strain-sensitive resistance film, the accuracy of pressure measurement is stabilized, and the temperature and strain composite sensor of the present invention can simultaneously detect temperature and pressure in the temperature range of -50°C or higher and 450°C or lower.

[0008] Preferably, the absolute value of the sensitivity temperature coefficient (TCS t ) of the temperature-sensitive resistance film in the temperature range of -50°C or higher and 450°C or lower is 500 ppm / °C or less.

[0009] Also preferably, the temperature-sensitive resistance film satisfies TCR t ≥ (2.5 × k t × ε t ). In this conditional expression, TCR t is the temperature coefficient of resistance of the temperature-sensitive resistance film, k t is the gauge factor of the temperature-sensitive resistance film, and ε t is the maximum amount of strain applied to the installation location of the temperature-sensitive resistance film. Since the temperature and strain composite sensor of the present invention has the above characteristics, a resolution of 1°C or less can be obtained in temperature measurement in the range of -50°C or higher and 450°C or lower.

[0010] Preferably, the gauge factor k of the strain-sensitive resistance film in the temperature range of -50°C or higher and 450°C or lower d is 4 or more, the temperature-sensitive resistance film has a TCR t ≧ (10 × k t × ε t ). Since the temperature-sensitive and strain-sensitive composite sensor of the present invention has the above characteristics, a resolution of 200 με or less can be obtained in pressure measurement in the range of -50°C or higher and 450°C or lower.

[0011] Preferably, each composition region of x and y in the strain-sensitive resistance film is 25 < x ≤ 50, 0.1 ≤ y ≤ 20. In the temperature-sensitive and strain-sensitive composite sensor of the present invention, since the strain-sensitive resistance film satisfies the above composition, the characteristic change (TCR of the strain-sensitive resistance film d change) accompanying the composition change of the strain-sensitive resistance film can be suppressed, and good productivity can be obtained. In addition, the accuracy of pressure measurement can be further improved by suppressing the variation in the TCR d characteristics of the strain-sensitive resistance film.

Brief Description of the Drawings

[0012]

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Figure 8

[0013] In the present embodiment, as an example of the temperature and strain sensitive sensor according to the present invention, a composite sensor 10 (FIG. 1) that simultaneously detects the temperature of a fluid and the fluid pressure will be described.

[0014] As shown in FIG. 1, the composite sensor 10 has a membrane 22 that deforms in response to fluid pressure. The membrane 22 is formed by an end wall formed at the upper end of the Z-axis of the hollow cylindrical stem 20. The membrane 22, which is an end wall, is thinner than other portions of the stem 20 such as the side wall. Note that the membrane 22 is not limited to the state shown in FIG. 1 and may be formed of a flat substrate such as an Si substrate. The lower end of the Z-axis of the stem 20 is an open end of the hollow portion, and the hollow portion of the stem 20 communicates with the flow path 12b of the connecting member 12.

[0015] In the composite sensor 10, the fluid introduced into the flow path 12b is guided from the hollow portion of the stem 20 to the inner surface 22a of the membrane 22 so that the fluid pressure is applied to the membrane 22. The stem 20 having the membrane 22 can be formed of a metal such as stainless steel, for example. Alternatively, the stem 20 may be formed of an Si substrate processed into a hollow cylindrical shape by etching, or may be formed by joining a flat Si substrate to other members.

[0016] 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 pressing member 14 so that the flow path 12b leading to the inner surface 22a of the membrane 22 is sealed.

[0017] The connecting member 12 has a thread groove 12a for fixing the composite sensor 10. The composite sensor 10 is fixed to a pressure chamber or the like in which the fluid to be measured is enclosed via the thread groove 12a. Thereby, the inner surface 22a of the diaphragm 22 in the flow path 12b and the stem 20 formed inside the connecting member 12 communicates airtightly with the pressure chamber in which the fluid to be measured is present inside.

[0018] A circuit board 70 is attached to the upper surface of the pressing member 14. The shape of the circuit board 70 is not particularly limited. For example, as shown in FIG. 1, it can be a ring shape surrounding the stem 20. The circuit board 70 incorporates, for example, a circuit to which signals regarding the temperature and strain detected by the diaphragm 22 are transmitted.

[0019] As shown in FIG. 2, a strain measurement section S1 and a temperature measurement section S2 are provided on the outer surface 22b of the diaphragm 22. The strain measurement section S1 and the temperature measurement section S2 are electrically connected to the circuit board 70 via an intermediate wiring 82 such as wire bonding, and the detection signals of the strain measurement section S1 and the temperature measurement section S2 are transmitted to the circuit board 70 via the intermediate wiring 82.

[0020] The strain measurement section S1 has four strain-sensitive resistors RD1 to RD4, a wiring W1, and an electrode section 50. In the strain measurement section S1, a Wheatstone bridge circuit is configured by the four strain-sensitive resistors RD1 to RD4. However, the strain measurement section S1 only needs to have at least one strain-sensitive resistor RD, and the number of strain-sensitive resistors RD is not particularly limited. For example, two or more Wheatstone bridge circuits may be formed on the interface 22b of the diaphragm 22. In the strain measurement section S1, the resistance values of the strain-sensitive resistors RD1 to RD4 change according to the deformation of the diaphragm 22. Therefore, the strain generated in the diaphragm 22, that is, the fluid pressure acting on the diaphragm 22, can be detected from the output of the Wheatstone bridge circuit.

[0021] On one hand, the temperature measurement unit S2 includes a temperature-sensitive resistor RT, a wiring W1, and an electrode portion 50. In the temperature measurement unit S2, the temperature-sensitive resistor RT is electrically connected to the electrode portion 50 via a wiring W2. In FIG. 2, only one temperature-sensitive resistor RT is illustrated, but the number of temperature-sensitive resistors RT is not particularly limited, and the temperature measurement unit S2 may have a plurality of temperature-sensitive resistors RT. In the temperature measurement unit S2, the resistance value of the temperature-sensitive resistor RT changes according to a temperature change, and based on this resistance change, the temperature of the fluid guided to the inner surface 22a of the membrane 22 is detected.

[0022] The temperature-sensitive resistor RT and the strain-sensitive resistors RD1 to RD4 are all formed on the same plane on the outer surface 22b of the membrane 22. The strain-sensitive resistors RD1 to RD4 are formed by microfabricating (patterning) a strain-sensitive resistive film 30, and the temperature-sensitive resistor RT is formed by microfabricating a temperature-sensitive resistive film 40. That is, the strain-sensitive resistor RD is the strain-sensitive resistive film 30, and the temperature-sensitive resistor RT is the temperature-sensitive resistive film 40.

[0023] As shown in FIG. 3, the strain-sensitive resistive film 30 and the temperature-sensitive resistive film 40 are provided on the outer surface 22b of the membrane 22 with an underlying insulating layer 60 interposed therebetween. The underlying insulating layer 60 is formed so as to cover substantially the entire outer surface 22b of the membrane 22. However, the underlying insulating layer 60 does not necessarily have to cover the entire outer surface 22b, and there may be an uncovered portion that is not covered by the underlying insulating layer 60 at the outer edge of the outer surface 22b.

[0024] The underlying insulating layer 60 only needs to have insulating properties, and the material of the underlying insulating layer 60 is not particularly limited. For example, the underlying insulating layer 60 can be composed of silicon oxides such as SiO 2 and silicon nitrides, silicon oxynitrides, etc. Also, when the membrane 22 is a Si substrate, the underlying insulating layer 60 may be a thermal oxide film formed by heating the Si substrate. The thickness of the underlying insulating layer 60 is preferably 10 μm or less, more preferably 1 to 5 μm. In addition, when the outer surface 22b of the membrane 22 has insulating properties, the resistive films 30 and 40 may be directly formed on the outer surface 22b of the membrane 22 without forming the underlying insulating layer 60.

[0025] Next, the characteristics of the strain-sensitive resistance film 30 and the temperature-sensitive resistance film 40 will be described.

[0026] Note that the temperature coefficient of resistance (TCR: Temperature coefficient of Resistance, unit ppm / ℃) used in the description of each resistance film 30, 40 means the change rate of resistance accompanying temperature change, and TCR = A / R(25℃, 0με) × 10 6 is defined by. A is the slope of the resistance value change in the range of -50℃ to 450℃, and R(25℃, 0με) is the resistance value at a temperature of 25℃ and a strain of 0με. The temperature coefficient of resistance of the strain-sensitive resistance film 30 is TCR d and is denoted as, and the temperature coefficient of resistance of the temperature-sensitive resistance film 40 is TCR t and is denoted as.

[0027] Also, the temperature coefficient of sensitivity (TCS: Temperature coefficient of sensitivity, unit ppm / ℃) used in the description of each resistance film 30, 40 is the change rate of the gauge factor (unit: dimensionless number) accompanying temperature change, and TCS = B / k 25℃ × 10 6 is defined by. B is the slope of the gauge factor change in the range of -50℃ to 450℃, and k 25℃ is the gauge factor at 25℃. The gauge factor and the temperature coefficient of sensitivity of the strain-sensitive resistance film 30 are denoted as k d , TCS d and the gauge factor and the temperature coefficient of sensitivity of the temperature-sensitive resistance film 40 are denoted as k t , TCS t and are denoted as.

[0028] (Strain-sensitive resistance film 30) The strain-sensitive resistance film 30 is represented by the general formula Cr 100-x-y Al x N y and the respective composition ranges of x and y are 5 < x ≤ 50, 0.1 ≤ y ≤ 20. By setting the strain-sensitive resistance film 30 to such a composition, in the temperature range of -50℃ or higher and 450℃ or lower, a higher gauge factor k dis obtained, and the gauge factor k d associated with temperature changes can be reduced. Therefore, by using the strain-sensitive resistance film 30 with the above composition in the composite sensor 10, strain (pressure) can be accurately detected in the temperature range of -50°C or higher and 450°C or lower.

[0029] In the above CrAlN-based strain-sensitive resistance film 30, the Al content is particularly important, and the composition range of x is preferably 25 < x ≤ 50, more preferably 25 < x ≤ 40.

[0030] After controlling the N content within a predetermined range, by setting the Al content to exceed 25 at%, changes in characteristics associated with changes in the composition of the strain-sensitive resistance film 30 can be suppressed. More specifically, when the Al content exceeds 25 at%, the change rate of TCR d with respect to a 1 at% change in the Al content can be suppressed to less than 5%. That is, variations in composition during manufacturing can be tolerated within an appropriate range, and good productivity can be obtained. Also, by suppressing variations in TCR d , the accuracy of strain measurement by the strain-sensitive resistance film 30 can be further improved.

[0031] Further, after controlling the N content within a predetermined range, by setting the Al content to 50 at% or less, more preferably 40 at% or less, the gauge factor k d of the strain-sensitive resistance film 30 can be made higher.

[0032] The strain-sensitive resistance film 30 may contain O as an unavoidable impurity in an amount of 10 at% or less based on the total amount of Cr, Al, N, and O. When the unavoidable impurity O is 10 at% or less, the gauge factor k d in the temperature range of -50°C or higher and 450°C or lower can be increased.

[0033] Furthermore, the strain-sensitive resistance film 30 may contain trace amounts of metal and non-metal elements other than Cr and Al. Examples of the metal and non-metal elements other than Cr and Al contained in the strain-sensitive resistance film 30 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.

[0034] In the temperature range of -50°C or higher and 450°C or lower, the strain-sensitive resistance film 30 has a TCR d with an absolute value of less than 2000 ppm / °C, preferably 1500 ppm / °C or lower. By controlling the TCR d of the strain-sensitive resistance film 30 within the above range, it is possible to reduce the change in the resistance value of the strain-sensitive resistance film 30 accompanying temperature changes in a wide range from the low temperature region to the high temperature region. As a result, the temperature correction error in the strain measurement unit S1 can be reduced, and strain can be detected with high accuracy.

[0035] In the temperature range of -50°C or higher and 450°C or lower, the strain-sensitive resistance film 30 has a gauge factor k d of 3 or more, preferably 4 or more. In the strain-sensitive resistance film 30, the larger the gauge factor k d , the larger the change in the resistance value with respect to strain. Therefore, by setting the gauge factor k d of the strain-sensitive resistance film 30 to 4 or more, the resolution of strain measurement in the range of -50°C or higher and 450°C or lower can be improved. Note that the upper limit value of the gauge factor k d is not particularly limited.

[0036] Also, in the temperature range of -50°C or higher and 450°C or lower, the strain-sensitive resistance film 30 has a TCS d with an absolute value of 2000 ppm / °C or lower, preferably 1000 ppm / °C or lower, and more preferably 500 ppm / °C or lower. The TCS dBy controlling it within the above range, it is possible to reduce the change in the sensitivity of the strain-sensitive resistance film 30 accompanying temperature change in a wide range from the low-temperature region to the high-temperature region. As a result, the temperature correction error in the strain measurement unit S1 can be reduced, and strain can be detected with high accuracy.

[0037] Note that TCR d , k d , and TCS d basically depend on the main component composition of the strain-sensitive resistance film 30, but may also change depending on trace elements in the strain-sensitive resistance film 30 and manufacturing conditions such as heat treatment.

[0038] The thickness of the strain-sensitive resistance film 30 is not particularly limited, and for example, it can be 1 nm to 1000 nm, and preferably about 50 nm to 500 nm.

[0039] Note that the arrangement of the strain-sensitive resistance film 30 (RD) on the outer surface 22b of the membrane 22 is not particularly limited, but it is desirable to arrange it as close as possible to the center of the outer surface 22b. As shown in the upper figure of FIG. 2, in the membrane 22, the larger the strain occurs closer to the center of the outer surface 22b, and the strain becomes zero at the outer edge of the outer surface 22b in contact with the side wall of the stem 20. In FIG. 2, RD1 and RD3 among the four temperature-sensitive resistance films 40 are arranged on the first circumference 24 where a predetermined strain characteristic ε1 occurs, and RD2 and RD4 are arranged on the second circumference 26 where a strain characteristic ε2 different from the strain characteristic ε1 occurs. When forming a plurality of strain-sensitive resistance films 30 (RD), as described above, the arrangement of the strain-sensitive resistance films 30 may be determined by dividing them into a plurality of resistance groups, or all the strain-sensitive resistance films 30 may be arranged on the same circumference.

[0040] (Temperature-sensitive resistance film 40) The temperature-sensitive resistance film 40 is made of a material different from that of the strain-sensitive resistance film 30, and the absolute value of TCR t in the temperature range of -50°C or higher and 450°C or lower is 2000 ppm / °C or higher. In the temperature-sensitive resistance film 40, by setting TCR t to 2000 ppm / °C or higher, the amount of change in the resistance value with respect to temperature change becomes large. Therefore, 2000 ppm / °C ≤ TCRt By using the temperature-sensitive resistance film 40, the temperature of the fluid can be detected with high accuracy in the range of -50°C or higher and 450°C or lower. As described above, the larger the TCR t , the larger the resistance change amount with respect to a 1°C temperature change. Therefore, the upper limit of the TCR t is not particularly limited.

[0041] Examples of the material of the temperature-sensitive resistance film 40 that satisfies a TCR of 2000 ppm / °C or higher include transition metals and alloys containing one or more transition metals. The temperature-sensitive resistance film 40 is preferably a metal film containing one or more elements selected from Fe, Ni, Cu, and Pt. t The thickness of the temperature-sensitive resistance film 40 is not particularly limited and can be, for example, 1 nm to 1000 nm, and is preferably about 50 nm to 500 nm.

[0042] The temperature-sensitive resistance film 40 preferably has a gauge factor k

[0043] in the temperature range of -50°C or higher and 450°C or lower that is 4 or less, and more preferably 3 or less. Note that the lower limit value of the gauge factor k t is not particularly limited, and 0 < k t . In the temperature-sensitive resistance film 40, by reducing the gauge factor k t , the change in the resistance value of the temperature-sensitive resistance film 40 due to strain can be reduced in a wide range from the low temperature region to the high temperature region, and the resolution of temperature measurement is improved. t

[0044] In addition, the temperature-sensitive resistance film 40 preferably has an absolute value of TCS t in the temperature range of -50°C or higher and 450°C or lower that is 500 ppm / °C or less. Note that TCR t , k t , and TCS t basically depend on the main component composition of the temperature-sensitive resistance film 40, but may also change depending on trace elements in the temperature-sensitive resistance film 40 and manufacturing conditions such as heat treatment.

[0045] In this embodiment, the arrangement of the temperature-sensitive resistance film 40 needs to be determined in consideration of various characteristics of the resistance film. In conventional pressure sensors and the like, a technique of installing a temperature compensation resistor at a position where no strain is applied, such as the outer edge portion of the membrane, has been used. However, at a position where no strain is applied, it is difficult to transmit the temperature of the fluid, and a difference occurs between the actual fluid temperature and the detected temperature. Therefore, in the composite sensor 10 that simultaneously detects the temperature and pressure of the fluid, the temperature-sensitive resistance film 40 is arranged within the region where strain occurs on the outer surface 22b of the membrane 22.

[0046] However, when the temperature-sensitive resistance film 40 is arranged in the strain generation region, the resistance value of the temperature-sensitive resistance film 40 changes not only due to temperature but also due to strain, which affects the resolution of temperature measurement and the resolution of strain measurement. Therefore, in the composite sensor 10 of this embodiment, it is preferable to determine the characteristics (i.e., material and manufacturing conditions) and installation location of the temperature-sensitive resistance film 40 so as to satisfy the following conditional expression 1 or / and conditional expression 2.

[0047] Specifically, when the temperature-sensitive resistance film 40 satisfies the conditional expression 1: TCR t ≧(2.5×k t ×ε t ), it is preferable. When the above conditional expression 1 is transformed, 1≦{TCR t / (2.5×k t ×ε t )}. Here, ε t in the conditional expression 1 is the maximum strain amount applied to the installation location of the temperature-sensitive resistance film 40. This ε t can be obtained by simulation based on information such as the materials, dimensions, and shapes of the membranes 22 having the resistance films 30 and 40 and the underlying insulating layer 60. By the temperature-sensitive resistance film 40 satisfying the conditional expression 1, the resolution of temperature measurement in the range of -50°C or higher and 450°C or lower can be made 1°C or lower. Note that the resolution of temperature measurement means the minimum temperature change that can be detected, and it can be said that the smaller the numerical value, the better the resolution.

[0048] Also, after setting the gauge factor k d of the strain-sensitive resistance film 30 to 4 or more, the temperature-sensitive resistance film 40 satisfies the conditional expression 2: TCRt ≧ (10 × k t × ε t ) is preferably satisfied. When converting Conditional Expression 2, 1 ≤ {TCR t / (10 × k t × ε t )} is obtained. Here, in the measurement of strain, the amount of resistance change shifted due to the measurement error of the temperature-sensitive resistance film 40 is defined as ΔR ΔT . When the gauge factor k d of the strain-sensitive resistance film 30 is 4 or more and, in addition, the temperature-sensitive resistance film 40 satisfies Conditional Expression 2, ΔR ΔT can be reduced. As a result, the resolution of strain measurement in the range of -50°C or higher and 450°C or lower can be set to 200 με or lower. The resolution of strain measurement means the minimum detectable strain amount, and it can be said that the smaller the numerical value, the better the resolution.

[0049] Next, a method for manufacturing the membrane 22 (stem 20) having each resistance film 30, 40 will be described. First, the hollow cylindrical stem 20 can be manufactured by subjecting a metal plate such as a stainless steel plate to machining such as pressing. At this time, the stem 20 is machined so that the end wall of the stem 20 that becomes the membrane 22 is thinner than other parts. Then, the base insulating layer 60 is formed on the outer surface 22b of the membrane 22 by a vapor deposition method such as CVD.

[0050] After the formation of the base insulating layer 60, the strain-sensitive resistance film 30, the temperature-sensitive resistance film 40, and the electrode portion 50 are formed on the base insulating layer 60. First, each resistance film 30, 40 is formed by a thin film method such as sputtering or vapor deposition using a DC sputtering apparatus or an RF sputtering apparatus. The film formation order of the strain-sensitive resistance film 30 and the temperature-sensitive resistance film 40 is not particularly limited. After the film formation of each resistance film 30, 40, fine processing by semiconductor processing techniques such as laser processing and screen printing is performed to control the formation position and planar shape of the resistance films 30, 40.

[0051] Note that when forming the piezoresistive resistive film 30, O or N that remains in the reaction chamber without being completely removed may be incorporated into the piezoresistive resistive film 30. The content of O or N in the composition of the piezoresistive resistive film 30 may be determined by O or N incorporated during film formation as described above. Alternatively, by using oxygen gas or nitrogen gas as the atmosphere gas during film formation or annealing and intentionally controlling the introduction amount of these oxygen gas or nitrogen gas, the content of O or N in the composition of the piezoresistive resistive film 30 may be controlled.

[0052] Also, after forming the piezoresistive resistive film 30, it is preferable to perform heat treatment on the resistive film. The heat treatment temperature at that time is not particularly limited, and for example, it can be set to 50°C to 550°C, and preferably 350°C to 550°C.

[0053] After forming each resistive film 30, 40 in a predetermined pattern, the electrode portion 50 is formed at a position as shown in FIG. 2 so as to be electrically connected to each resistive film 30, 40. The electrode portion 50 can be formed by a thin film method such as sputtering or vapor deposition in the same manner as each resistive film 30, 40. The material of the electrode portion 50 can be a conductive metal or alloy, and for example, it is preferably included Cr, Ti, Ni, Mo, platinum group elements, etc. Also, the electrode portion 50 may have a multilayer structure with different materials.

[0054] By the above method, a membrane 22 (stem 20) having a strain measurement unit S1 and a temperature measurement unit S2 is obtained.

[0055] As described above, the embodiments of the present invention have been described, but the present invention is not limited to the above-described embodiments at all, and various modifications can be made without departing from the gist of the present invention.

Examples

[0056] Hereinafter, the present invention will be described based on more detailed examples, but the present invention is not limited to these examples. In the table shown below, the sample numbers marked with ※ are comparative examples.

[0057] (Experiment 1) In Experiment 1, Sample 1 with a CrN-based strain-sensitive resistance film, Sample 2 with a CrAl-based strain-sensitive resistance film, and Samples 3 to 4 with a CrAlN-based strain-sensitive resistance film were fabricated. Then, for each fabricated sample, the film composition, temperature coefficient of resistance (TCR d ), gauge factor k d , and temperature coefficient of sensitivity (TCS d ) were measured.

[0058] Sample preparation First, the Si substrate was heated to form a SiO 2 film, which is a thermal oxide film, on the substrate surface. Then, using a DC sputtering apparatus, a strain-sensitive resistance film was formed on the surface of the SiO 2 film. Further, after heat-treating the formed strain-sensitive resistance film at 350°C, a strain-sensitive resistor (RD) that constitutes a Wheatstone bridge circuit was formed by microfabrication. Finally, an electrode portion was formed on the surface of the strain-sensitive resistance film by electron evaporation to obtain a sample for evaluating the characteristics of the strain-sensitive resistance film.

[0059] Note that in the film formation of the strain-sensitive resistance film, the Al content was controlled by adjusting the number of Cr targets and Al targets used in the DC sputtering apparatus and the potential of each target. Also, as the atmospheric gas during film formation, Ar gas and a small amount of nitrogen gas were used, and the N content was controlled by the ratio of nitrogen gas in the atmospheric gas. Further, the film thickness of the strain-sensitive resistance film was set to 300 nm for all samples.

[0060] Composition analysis The composition of the strain-sensitive resistance film in Samples 1 to 4 was analyzed by the XRF (X-ray fluorescence) method.

[0061] Measurement of temperature coefficient of resistance For each sample (Samples 1 to 4), while changing the temperature of the measurement environment from -50°C to 450°C, the resistance value was measured to obtain a graph showing the change tendency of the resistance value with respect to the temperature change. Then, the slope A of the graph was obtained by linear approximation using the least squares method, and from the slope A, the TCR dwas calculated. The calculated TCR d has a reference temperature of 25°C.

[0062] Measurement of gauge factor and temperature coefficient of sensitivity For each sample (Samples 1 to 4), while changing the temperature of the measurement environment from -50°C to 450°C, the gauge factor k d was measured, and a graph showing the trend of the change in the gauge factor k d with respect to the temperature change as shown in Fig. 4 was obtained. Then, the slope B of the graph was obtained by linear approximation using the least squares method, and from the slope B, the TCS d of each sample was calculated. The calculated TCS d has a reference temperature of 25°C.

[0063] The composition analysis results, TCR d , gauge factor k d , and TCS d of each sample are shown in Table 1 and Fig. 4.

Table 1

[0064] As shown in Table 1 and Fig. 4, Sample 1 of the CrN-based alloy film has a high gauge factor in the low temperature range from -50°C to 150°C, but in the high temperature range of 200°C or higher, the gauge factor extremely decreases. Therefore, when using the CrN-based alloy film as a strain-sensitive resistance film, it was found that the accuracy of pressure measurement cannot be obtained in the high temperature range of 200°C or higher. In Sample 2, although Al is contained, the Al content is 5 at% or less, and the gauge factor decreases in the high temperature range of 200°C or higher, and a stable gauge factor cannot be ensured.

[0065] On the other hand, the general formula Cr 100-x-y Al x N yFor Samples 3 and 4 using a CrAlN alloy film represented by [formula] and satisfying 5 < x ≤ 50, 0.1 ≤ y ≤ 20, a high gauge factor could be stably ensured in the range of -50°C to 450°C. From this result, it was found that by using a CrAlN alloy film satisfying a predetermined composition as a strain-sensitive resistance film, pressure measurement with high accuracy is possible in the range of -50°C to 450°C.

[0066] (Experiment 2) In Experiment 2, for the strain-sensitive resistance film 30 represented by the general formula Cr 100-x-y Al x N y nine samples with different Al contents (values of x) were prepared to evaluate the relationship between the composition range and the gauge factor. Then, the composition (Al content) of each sample and the gauge factor k d at 25°C were measured. The production method of each sample and the measurement method of the gauge factor in Experiment 2 were the same as those in Experiment 1. The evaluation results of Experiment 2 are shown in Fig. 5. In Fig. 5, the measurement results of each sample in Experiment 2 were plotted with the Al content on the horizontal axis and the gauge factor k d of the strain-sensitive resistance film 30 on the vertical axis. Although the N content is not shown in Fig. 5, in all samples of Experiment 2, 0.1 ≤ y ≤ 20.

[0067] As shown in Fig. 5, for samples with x ≤ 50, a gauge factor sufficiently larger than 2.6, which is the gauge factor of general metals, was obtained, and it was found that they could be suitably used as the strain-sensitive resistance film 30. In particular, by setting the Al content to x ≤ 40, it was found that the gauge factor k d became 4 or more, and the sensitivity of pressure measurement was good.

[0068] (Experiment 3) In Experiment 3, for the strain-sensitive resistance film 30 represented by the general formula Cr 100-x-y Al x N y eight samples with different Al contents (values of x) were prepared to evaluate the relationship between the composition range and the TCR d . Then, the composition (Al content) of each sample and the TCR d were measured. The production method of each sample and the TCR in Experiment 3d The measurement method was the same as in Experiment 1. The evaluation results of Experiment 3 are shown in Fig. 6. In Fig. 6, the Al content is on the horizontal axis and the TCR d is on the vertical axis, and the measurement results of each sample in Experiment 3 are plotted. Although the N content is not shown in Fig. 6, in all samples of Experiment 3, 0.1 ≦ y ≦ 20.

[0069] As shown in Fig. 6, for the four samples with 0 ≦ x ≦ 25 of the Al content, the slope of the TCR d with respect to the unit composition change of Al (horizontal axis) is large, and the absolute value of the slope calculated by linearly approximating each plot by the least squares method was 105. On the other hand, for the four samples with 25 < x ≦ 50 of the Al content, the slope of the TCR with respect to the unit composition change of Al (horizontal axis) is small, and the absolute value of the slope calculated by linearly approximating each plot by the least squares method was 16.

[0070] That is, in the samples with 25 < x ≦ 50 of the Al content, it was found that the change rate of the TCR d with respect to the variation of the Al content of 1 at% can be suppressed to less than 5%, and the characteristic change accompanying the composition change can be significantly suppressed.

[0071] (Experiment 4) In Experiment 4, four samples (Samples 5 to 8) having the piezoresistive film 30 and the temperature-sensitive resistive film 40 were fabricated.

[0072] Sample 5 Specifically, in Sample 5, the piezoresistive film 30 represented by the general formula Cr 100-x-y Al x N y and satisfying 5 < x ≦ 50, 0.1 ≦ y ≦ 20 was formed on the surface of the SiO 2 film of the Si substrate using a DC sputtering apparatus. Then, after heat-treating the piezoresistive film 30 at 350°C, the piezoresistive film 30 was microfabricated to form a Wheatstone bridge circuit. Also, the temperature-sensitive resistive film 40 was formed at a position where the maximum strain amount ε t is 200 με. In Sample 5, the temperature-sensitive resistive film 40 has the general formula Cr 100-x-y Alx N y It is represented by and satisfies 5 < x ≤ 50, 0.1 ≤ y ≤ 20, and has the same composition as the piezoresistive film 30. Finally, the electrode portion was formed by electron beam evaporation to obtain Sample 5 as a temperature and piezoresistive composite sensor.

[0073] Sample 6 In Sample 6, the general formula Cr 100-x-y Al x N y A piezoresistive film 30 represented by and satisfying 5 < x ≤ 50, 0.1 ≤ y ≤ 20 and a temperature-sensitive resistive film 40 made of a Pt-based alloy thin film were formed. In Sample 6, although the composition of each resistive film was different from that of Sample 5, the experimental conditions other than the composition were the same as those of Sample 5.

[0074] Sample 7 In Sample 7, the general formula Cr 100-x-y Al x N y A piezoresistive film 30 represented by and satisfying 5 < x ≤ 50, 0.1 ≤ y ≤ 20 and a temperature-sensitive resistive film 40 made of a Cu-based alloy thin film were formed. In Sample 7, although the composition of each resistive film was different from that of Sample 5, the experimental conditions other than the composition were the same as those of Sample 5.

[0075] Sample 8 In Sample 8, the general formula Cr 100-x-y Al x N y A piezoresistive film 30 represented by and satisfying 5 < x ≤ 50, 0.1 ≤ y ≤ 20 and a temperature-sensitive resistive film 40 made of a Ni-based alloy thin film were formed. In Sample 8, although the composition of each resistive film was different from that of Sample 5, the experimental conditions other than the composition were the same as those of Sample 5.

[0076] For each of Samples 5 to 8 in Experiment 4, the temperature coefficient of resistance, gauge factor, and sensitivity temperature coefficient of each resistance film 30, 40 were measured in the same manner as in Experiment 1. Also, for each sample, the resolution of temperature measurement and the resolution of strain measurement in the range of -50°C to 450°C were calculated. Regarding the resolution of temperature measurement, when the resolution of 1°C or less was always obtained in the temperature range of -50°C to 450°C, it was judged as qualified (G), and when the resolution exceeded 1°C in the temperature range of -50°C to 450°C, it was judged as unqualified (F). The evaluation results of Experiment 4 are shown in Table 2. Note that the gauge factors (k d 、k t ) shown in Table 2 are the measurement results at 25°C.

[0077]

Table 2

[0078] As shown in Table 2, in Sample 5 in which the strain-sensitive resistance film 30 and the temperature-sensitive resistance film 40 were made of the same material, the resolution of temperature measurement was poor. When the temperature-sensitive resistance film 40 was arranged at a location where ε t was 200 με, a temperature change of 1°C could not be accurately measured. Also, in Sample 5, in strain measurement, the resistance change amount ΔR ΔT shifted due to the measurement error of the temperature-sensitive resistance film 40 and became large, and the resolution of strain measurement became 400 με. That is, in Sample 5, a strain amount less than 400 με could not be detected, and the accuracy of strain measurement could not be obtained.

[0079] On the other hand, in Samples 6 to 8, as the temperature-sensitive resistance film 40, a metal film having a composition different from that of the strain-sensitive resistance film 30 and having a TCR t of 2000 ppm / °C or more was used. In these Samples 6 to 8, in the temperature range of -50°C to 450°C, the resolution of temperature measurement was always 1°C or less, and temperature measurement was possible with sufficient accuracy. Also, the resolution of strain measurement was 200 με or less, and in Samples 6 to 8, the accuracy of strain measurement was improved compared to Sample 5.

[0080] Note that by comparing the evaluation results of Samples 6 to 8, the TCR tIt was found that the higher it is, the further the resolution of temperature measurement and the resolution of strain measurement are improved. Also, the gauge factor k of the temperature-sensitive resistance film 40 t It was found that the lower it is, the further the resolution of temperature measurement and the resolution of strain measurement are improved.

[0081] (Experiment 5) In Experiment 5, nine samples were prepared by changing the material and installation location of the temperature-sensitive resistance film 40. The manufacturing method of the samples in Experiment 5 was the same as that in Experiment 4. Then, for each sample in Experiment 5, the resistance change amount ΔR’’ of the temperature-sensitive resistance film 40 when the maximum strain amount ε t was applied t was measured. The measurement of ΔR’’ t for each sample was carried out under the conditions of environmental temperature: -50°C, 25°C, 450°C. The evaluation results of Experiment 5 are shown in Fig. 7.

[0082] In Fig. 7, the TCR t / (2.5×k t ×ε t ) is taken as the horizontal axis, and ΔR’’ t is taken as the vertical axis, and the measurement results of each sample are plotted. The smaller ΔR’’ t is, the better the resolution of temperature measurement can be said to be. More specifically, the reference line RL1 shown in Fig. 7 is the resistance change amount ΔR’ of the temperature-sensitive resistance film 40 caused by a temperature change of 1°C. When the plot of the measurement result is below the reference line RL1 (that is, when ΔR’’ t <ΔR’), the resistance change amount associated with the temperature change is larger than the resistance change amount caused by the maximum strain amount ε t , and a temperature change of 1°C can be measured. That is, if the plots at -50°C, 25°C, and 450°C are all below the reference line RL1, it can be judged that the resolution of temperature measurement is always 1°C or less in the range of -50°C to 450°C.

[0083] As shown in Fig. 7, 0.5≦{TCR t / (2.5×k t ×ε t)} In the range of < 1.0, the plots at -50°C and 25°C were below the reference line RL1. However, the plot at 450°C was above the reference line RL1, and in the high-temperature range of 450°C, a resolution of 1°C or less could not be obtained.

[0084] On the other hand, in the range of 1.0 ≤ {TCR t / (2.5 × k t × ε t )}, all the plots from -50°C to 450°C were below the reference line RL1, and a resolution of 1°C or less was always obtained in the range of -50°C to 450°C.

[0085] (Experiment 6) In Experiment 6, seven samples were prepared by changing the material and installation location of the temperature-sensitive resistance film 40. The manufacturing method of the samples in Experiment 6 was the same as that in Experiment 4. Then, for each sample in Experiment 6, the resistance change amount ΔR ΔT shifted due to the measurement error of the temperature-sensitive resistance film 40 was calculated. The evaluation results of Experiment 6 are shown in Fig. 8.

[0086] In Fig. 8, with TCR t / (10 × k t × ε t ) on the horizontal axis and ΔR ΔT on the vertical axis, the measurement results of each sample were plotted. The reference line RL2 shown in Fig. 8 is the resistance change amount ΔR’’ d that occurs when the strain-sensitive resistance film 30 with k d = 4 is subjected to a strain of 200 με at 450°C. Similarly, the reference line RL3 is the resistance change amount ΔR’’ d that occurs when the strain-sensitive resistance film 30 with k d = 4 is subjected to a strain of 200 με at -50°C. In the measurement of strain, if the resistance change amount ΔR’’ n when a predetermined strain ε d is applied to the strain-sensitive resistance film 30 is larger than ΔR ΔT , the predetermined strain ε n can be accurately detected. That is, if the plot of ΔR ΔT is below both the reference lines RL2 and RL3, a resolution of 200 μm or less can always be obtained in the temperature range of -50°C to 450°C.

[0087] As shown in Fig. 8, in the range of 0.4 ≦ {TCR t / (10 × k t × ε t )} < 1.0, ΔR ΔT falls below the reference line RL3 but exceeds the reference line RL2. That is, when 0.4 ≦ {TCR t / (10 × k t × ε t )} < 1.0, a strain of 200 με can be detected at -50°C, but a strain of 200 με cannot be detected at 450°C.

[0088] On the other hand, in the range of 1.0 ≦ {TCR t / (10 × k t × ε t )}, ΔR ΔT falls below both the reference lines RL2 and RL3, and it was found that a resolution of always 200 με or less can be obtained in the range of -50°C to 450°C.

[0089] Note that the reference line RL4 shown in Fig. 8 is the resistance change amount ΔR’’ d generated when the strain-sensitive resistance film 30 with k d = 3 receives a strain of 200 με at 450°C. When using the strain-sensitive resistance film 30 with k d = 3 and a gauge factor of less than 4, it was found that a resolution of 200 με or more can be obtained by satisfying 1.3 ≦ {TCR t / (10 × k t × ε t )}.

Explanation of Symbols

[0090] 10 … Temperature and Strain Composite Sensor 12 … Connecting Member 12a … Thread Groove 12b … Flow Path 14 … Pressing Member 70 … Circuit Board 82 … Intermediate Wiring 20 … Stem 21 … Flange Portion 22 … Membrane 22a … Inner surface 22b … Outer surface 30 … Strain-sensitive resistive film 40 … Temperature-sensitive resistive film 50 … Electrode portion 60 … Underlying insulating layer

Claims

1. General formula Cr 100-x-y Al x N y represented by, a piezoresistive film in which the respective composition ranges of x and y are 5 < x ≤ 50, 0.1 ≤ y ≤ 20, and - A temperature-sensitive resistive film having an absolute value of the temperature coefficient of resistance (TCR) in the temperature range of -50 °C or higher and 450 °C or lower being 2000 ppm / °C or higher. - A temperature and strain composite sensor in which an absolute value of the sensitivity temperature coefficient (TCS) of the temperature-sensitive resistive film in the temperature range of -50 °C or higher and 450 °C or lower is 500 ppm / °C or lower.

2. - The gauge factor k of the strain-sensitive resistance film in the temperature range of -50 °C or higher and 450 °C or lower d is 4 or more, Let TCR be the temperature coefficient of resistance of the temperature-sensitive resistive film t and let k be the gauge factor of the temperature-sensitive resistive film t and let ε be the maximum amount of strain applied to the location where the temperature-sensitive resistive film is installed t then TCR t ≥ (10 × k t × ε t ), wherein the temperature-sensitive and strain-sensitive composite sensor according to claim 1 is satisfied.

3. A strain-sensitive resistive film represented by the general formula Cr100 - x - yAlxNy, where the respective composition ranges of x and y are 5 < x ≤ 50, 0.1 ≤ y ≤ 20. - A temperature-sensitive resistive film having an absolute value of the temperature coefficient of resistance (TCR) in the temperature range of -50 °C or higher and 450 °C or lower being 2000 ppm / °C or higher. - In the temperature range of -50 °C or higher and 450 °C or lower, the gauge factor kd of the strain-sensitive resistive film is 4 or more. Let the temperature coefficient of resistance of the temperature-sensitive resistive film be TCRt, the gauge factor of the temperature-sensitive resistive film be kt, and the maximum strain amount applied to the installation location of the temperature-sensitive resistive film be εt. A temperature and strain composite sensor satisfying TCRt ≥ (10 × kt × εt).

4. The temperature and strain composite sensor according to any one of Claims 1 to 3, wherein the respective composition ranges of x and y in the strain-sensitive resistive film are 25 < x ≤ 50, 0.1 ≤ y ≤ 20.

5. A strain-sensitive resistive film represented by the general formula Cr100 - x - yAlxNy, where the respective composition ranges of x and y are 25 < x ≤ 50, 0.1 ≤ y ≤ 20. - A temperature and strain composite sensor having a temperature-sensitive resistive film having an absolute value of the temperature coefficient of resistance (TCR) in the temperature range of -50 °C or higher and 450 °C or lower being 2000 ppm / °C or higher.

6. Let the temperature coefficient of resistance of the temperature-sensitive resistance film be TCR t and let the gauge factor of the temperature-sensitive resistance film be k t and let the maximum amount of strain applied to the installation location of the temperature-sensitive resistance film be ε t Then TCR t ≥ (2.5 × k t × ε t ), wherein the temperature-sensitive and strain-sensitive composite sensor according to claim 1 or 5 is satisfied.

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