JP5672742B2 - Infrared temperature sensor - Google Patents

Description

  The present invention relates to an infrared temperature sensor for non-contact measurement of a temperature of a heat source.

  As a sensor for detecting infrared rays radiated from a heat source, for example, an infrared detection device disclosed in JP-A-6-281750 is known. This infrared detection device includes a pair of detection thermistors formed on a semiconductor substrate without a thermal insulating film, and a pair of compensation thermistors formed on the semiconductor substrate via a thermal insulating film. It has a thermistor bridge circuit comprising a thermistor. Since the thermistor for detection is formed in contact with the semiconductor substrate, heat from infrared rays easily escapes to the semiconductor substrate and exhibits a resistance change with a steep response speed. On the other hand, since the compensation thermistor is not in contact with the semiconductor substrate but is formed on the thermal insulating film, the heat from the infrared rays hardly escapes to the semiconductor substrate and exhibits a resistance change at a slow response speed. For this reason, a voltage change corresponding to a change in the amount of received infrared light is output from the thermistor bridge circuit with high sensitivity.

JP-A-6-281750

  However, if a deviation occurs between the response speed of the detection thermistor and the response speed of the compensation thermistor, the rise of the output signal of the thermistor bridge circuit when receiving infrared light tends to become unstable, and from the viewpoint of response stability. It was not enough.

  Therefore, an object of the present invention is to propose an infrared temperature sensor excellent in sensitivity characteristics and response stability.

  In order to solve the above-mentioned problems, an infrared temperature sensor according to the present invention is an infrared temperature sensor that measures the temperature of a heat source in a non-contact manner, and detects a heat amount of infrared rays emitted from the heat source; A temperature-compensating thermal element that detects the amount of heat from the external environment, a substrate having a first principal surface on which the infrared-sensitive thermal element and the temperature-compensating thermal element are disposed, and a second principal surface that is the back surface thereof; The infrared detecting thermal element and the temperature compensating thermal element are arranged in a thin part thinner than the maximum thick part of the substrate. By forming each of the infrared detecting thermal element and the temperature compensating thermal element in a thin portion having a heat capacity smaller than that of the substrate, the infrared detecting thermal element and the temperature compensating thermal element react sensitively even with a small amount of heat. Therefore, the sensitivity characteristic of the infrared temperature sensor can be improved. In addition, by forming each of the infrared detection thermal element and the temperature compensation thermal element in a thin portion thermally arranged symmetrically with respect to the external environment, the response speed of the infrared detection thermal element and the temperature compensation thermal element The response speed can be made substantially the same, and the response stability of the infrared temperature sensor can be improved.

  The substrate preferably has a thick part thicker than the thin part between the infrared detecting thermal element and the temperature compensating thermal element. As a result, it is possible to increase the thermal resistance between the infrared detecting thermal element and the temperature compensating thermal element, and it is possible to suppress a decrease in temperature measurement accuracy due to the flow of heat between the two elements.

  The common electrode of the infrared detecting thermal element and the temperature compensating thermal element is preferably formed on the first main surface between the infrared detecting thermal element and the temperature compensating thermal element. Since the common electrode made of a conductive material is excellent in heat conduction, heat dissipation can be improved.

  The infrared temperature sensor preferably includes a protective film covering the infrared detecting thermal element and the temperature compensating thermal element. Thermal diffusion from the infrared detecting thermal element and the temperature compensating thermal element can be enhanced through the protective film.

  The infrared temperature sensor preferably includes an infrared reflecting film that covers at least a part of the temperature-compensating thermosensitive element. Infrared rays radiated from the heat source are reflected by the infrared reflection film so that the amount of heat of the infrared rays does not transfer to the temperature-compensating heat sensitive element.

  The projected area in the thickness direction of the substrate of the infrared reflective film is preferably larger than the projected area in the thickness direction of the thin substrate. As a result, since the heat quantity from the infrared rays flows directly to the substrate having a large heat capacity, it can be configured not to flow into the temperature compensation thermal element, so the temperature compensation thermal element can accurately detect the heat quantity from the external environment. .

  The infrared temperature sensor includes a first infrared absorbing film that covers at least a part of the temperature-compensating thermosensitive element, a first infrared reflecting film that covers at least a part of the first infrared absorbing film, and a thermal sensor for detecting infrared rays. It is preferable to include a second infrared reflection film that covers at least a part of the element and a second infrared absorption film that covers at least a part of the second infrared reflection film. The heat capacity of the laminated structure composed of the first infrared absorbing film and the first infrared reflecting film and the heat capacity of the laminated structure composed of the second infrared reflecting film and the second infrared absorbing film can be adjusted to be substantially the same. It is possible to equalize the influence of heat received from the external environment on each of the detection thermal element and the temperature compensation thermal element.

  The infrared temperature sensor further includes an infrared absorbing film that covers at least a part of the infrared detecting thermal element, and the projected area in the thickness direction of the substrate of the infrared absorbing film is smaller than the projected area in the thickness direction of the thin substrate. Is preferred. As a result, the amount of heat absorbed by the infrared absorption film can be confined in a thin portion without leaking to the substrate as much as possible, so that the sensitivity characteristics of the infrared detecting thermal element can be improved.

  The infrared reflection film is preferably connected to at least one of the output terminal electrode of the temperature compensation thermal element or the common electrode of the infrared detection thermal element and the temperature compensation thermal element. As a result, the amount of infrared heat can be efficiently radiated from the infrared reflecting film to the outside via the output terminal electrode or the common electrode, so that the influence of the temperature compensating thermosensitive element from the infrared rays is reduced, and the sensitivity of the infrared temperature sensor is reduced. The characteristics can be improved.

  The infrared temperature sensor further includes a protective film that covers the infrared detecting thermal element and the temperature compensating thermal element, and the protective film is provided between the infrared detecting thermal element and the common electrode or between the temperature compensating thermal element and the common electrode. It is preferable to have a recess recessed on the first main surface side. By forming a recess in the protective film in this way, the thermal resistance between the infrared detecting thermal element and the temperature compensating thermal element is increased, and the heat conduction from one element affects the temperature of the other element. You can avoid giving.

  According to the present invention, an infrared temperature sensor excellent in sensitivity characteristics and response stability can be provided.

1 is a circuit configuration diagram of an infrared temperature sensor according to Embodiment 1. FIG. FIG. 3 is an explanatory diagram illustrating a planar layout of each component of the infrared temperature sensor according to the first embodiment. 5 is a manufacturing process cross-sectional view of the infrared temperature sensor according to Embodiment 1. FIG. 5 is a manufacturing process cross-sectional view of the infrared temperature sensor according to Embodiment 1. FIG. 5 is a manufacturing process cross-sectional view of the infrared temperature sensor according to Embodiment 1. FIG. It is sectional drawing of the infrared temperature sensor concerning Embodiment 2. FIG. It is sectional drawing of the infrared temperature sensor concerning Embodiment 3. FIG. It is sectional drawing of the infrared temperature sensor concerning Embodiment 4.

  Embodiments according to the present invention will be described below with reference to the drawings. The same devices are denoted by the same reference numerals, and redundant description is omitted. The drawings are schematic, and for convenience of explanation, the relationship between thickness and planar dimensions, and the ratio of thickness between devices are within the range where the effect of the present invention can be obtained. May be different.

[Embodiment 1]
FIG. 1 is a circuit configuration diagram of an infrared temperature sensor 100 according to the present embodiment. The infrared temperature sensor 100 includes a half-bridge circuit composed of an infrared detection thermal element 20 and a fixed resistance element 41 connected in series via an output terminal electrode 51, and a temperature compensation thermal sensor connected in series via an output terminal electrode 52. It has a full bridge circuit in which a half bridge circuit composed of the element 30 and the fixed resistance element 42 is connected in parallel. An input terminal electrode 53 is connected between the fixed resistance elements 41 and 42, and a common electrode (ground terminal electrode) 50 is connected between the infrared detecting thermal element 20 and the temperature compensating thermal element 30. . A power source 60 is connected between the input terminal electrode 53 and the common electrode 50 so that a current flows through the full bridge circuit. The infrared detecting thermal element 20 is a sensor element for detecting the amount of heat of infrared rays emitted from the heat source, and the temperature compensating thermal element 30 is a sensor element for detecting the amount of heat from the external environment. The amount of heat received by the infrared detection thermal element 20 is not limited to the amount of infrared radiation radiated from the heat source, but also receives the amount of heat from the external environment, so the temperature compensation thermal element 30 detects the amount of heat from the external environment, The amount of infrared heat radiated from the heat source (ie, the temperature of the heat source) can be estimated. Therefore, the infrared detecting thermal element 20 is arranged so as to receive infrared rays emitted from the heat source, while the temperature compensating thermal element 30 does not receive infrared rays emitted from the heat source (in other words, Placed so that only the amount of heat from the external environment can be detected. The infrared detection thermal element 20 and the temperature compensation thermal element 30 are not particularly limited as long as the electrical characteristics change according to the amount of heat received. For example, a thermistor having resistance temperature characteristics A bolometer such as the above or a resistance temperature sensor is suitable. In addition, it is preferable that the resistance temperature characteristics of the infrared detecting thermal element 20 and the temperature compensating thermal element 30 are adjusted as much as possible so that the resistance value changes due to the amount of heat from the external environment are made uniform. Similarly, the resistance values of the fixed resistance elements 41 and 42 are preferably as identical as possible. Thereby, in the state where the infrared ray from the heat source is not irradiated to the infrared temperature sensor 100, the voltage between the output terminal electrodes 51 and 52 becomes zero, while in the state where the infrared temperature sensor 100 is irradiated with the infrared ray from the heat source, An unbalanced voltage is output between the output terminal electrodes 51 and 52 due to the difference in resistance value between the infrared detecting thermal element 20 and the temperature compensating thermal element 30. By preparing map data that associates the unbalanced voltage with the temperature of the heat source in advance, the temperature of the heat source can be estimated from the unbalanced voltage.

  2 is an explanatory diagram showing a planar layout of each component of the infrared temperature sensor 100, and FIG. 5 is a cross-sectional view taken along line 5-5 in FIG. The infrared detecting thermal element 20 includes an individual electrode 21 and a common electrode 50 that are formed with a predetermined gap interval, and a thermal film 22 that is formed between these electrodes. The temperature compensating thermosensitive element 30 includes an individual electrode 31 and a common electrode 50 that are formed with a predetermined gap interval, and a thermosensitive film 32 that is formed between these electrodes. As a material of the heat sensitive films 22 and 32, for example, a thermistor thin film having a negative temperature coefficient such as amorphous silicon, polysilicon, germanium, silicon carbide, composite metal oxide or the like is suitable. As the material of the individual electrodes 21 and 31 and the common electrode 50, a material having a relatively high melting point having heat resistance capable of withstanding the film-forming process or heat treatment process of the heat-sensitive films 22 and 32 and having appropriate conductivity. Preferably, for example, molybdenum (Mo), platinum (Pt), gold (Au), tungsten (W), tantalum (Ta), palladium (Pd), iridium (Ir), or an alloy containing two or more of these metals Is preferred. The output terminal electrodes 51 and 52 are pad electrodes for connecting to the individual electrodes 21 and 31, respectively, and taking out an electric signal, and the input terminal electrode 54 for applying a voltage to the element is a common electrode. The material is preferably a material that can be easily electrically connected, such as wire bonding or flip chip bonding, such as aluminum (Al) or gold (Au).

  The substrate 11 has a first main surface 11A and a second main surface 11B which is the back surface thereof, and an insulating film 12 is formed on each main surface. The material of the substrate 11 is not particularly limited as long as it has a suitable mechanical strength and is suitable for fine processing such as etching. For example, a silicon single crystal substrate, a sapphire single crystal A substrate, a ceramic substrate, a quartz substrate, a glass substrate, or the like is preferable. The insulating film 12 is not particularly limited as long as it has an appropriate mechanical strength and can be easily formed by a known thin film process. For example, a silicon oxide film, a silicon nitride film, etc. Etc. are suitable. On the first main surface 11A of the substrate 11, the infrared detecting thermal element 20, the temperature compensating thermal element 30, the fixed resistance elements 41 and 42, the output terminal electrodes 51 and 52, and the input terminal electrode 53 are insulating films. 12 is formed. Further, a protective film 13 is formed to cover the infrared detecting thermal element 20 and the temperature compensating thermal element 30 to shield from the outside air. Here, the protective film 13 only needs to cover at least the infrared detecting thermal element 20 and the temperature compensating thermal element 30, but the form exposed through the protective layer disclosed in FIG. 5 is more preferable. preferable. Such a configuration is advantageous in terms of heat dissipation, temperature uniformity, and reliability. The material of the protective film 13 is not particularly limited as long as it is an insulating film having moderate durability, but is preferably the same as the material of the insulating film 12. By doing in this way, since the insulating film which comprises the circumference | surroundings of the thermal element 20 for infrared rays detection and the thermal element 30 for temperature compensation becomes all the same material, a more uniform temperature distribution is preferable. The common electrode 50 is connected to an extraction electrode 54 for extracting an electric signal. Further, an infrared absorption film 70 for absorbing infrared rays radiated from a heat source, converting the energy into heat, and transferring the heat to the infrared detection thermal element 20 is provided through the protective film 13 for infrared detection. A film is formed so as to cover at least a part of the element 20. The material of the infrared absorbing film 70 is not particularly limited as long as it is a material that efficiently absorbs infrared rays of 4 μm to 10 μm. For example, black body materials such as Au black and Pt black, polyimide, etc. Resins with high infrared absorption efficiency are suitable. However, when the protective film 13 is a thin film (for example, a silicon oxide film) excellent in infrared absorption efficiency, the protective film 13 itself may function as the infrared absorption film 70. Further, the infrared reflection film 80 for reflecting the infrared rays radiated from the heat source and preventing the heat quantity of the infrared rays from being transferred to the temperature compensating thermal element 30 covers at least a part of the temperature compensating thermal element 30. It is formed into a film. The material of the infrared reflecting film 80 is not particularly limited as long as it is a thin film having an appropriate infrared reflectance. For example, a metal material such as aluminum (Al) or gold (Au) is suitable. In particular, a film that can be easily formed by a known thin film process and has excellent thermal conductivity is more preferable. Further, as the fixed resistance elements 41 and 42, those having a small temperature dependency of resistance change are preferable, and NiCr or the like that can be easily formed by a known thin film process is particularly preferable.

  Further, a cavity 91 is formed on the substrate 11 corresponding to the position where the infrared detecting thermal element 20 is disposed, and a cavity 92 is formed corresponding to the position where the temperature compensating thermal element 30 is disposed. ing. The cavities 91 and 92 are concave portions that are recessed into the substrate from the second main surface 11B side toward the first main surface 11A side, and are thin portions 14 that are thinner than the maximum thick portion 16 of the substrate 11, respectively. , 15. In other words, the infrared detecting thermal element 20 and the temperature compensating thermal element 30 are formed on the thin portions 14 and 15 of the substrate 11, respectively. FIG. 5 illustrates the case where the thin portions 14 and 15 are formed only by the insulating film 12, but the present embodiment is not limited to this, for example, the thin portion of the substrate 11 and the thin portion thereof. You may form by the combination with the insulating film 12 formed into a film on it. In addition, as long as the condition that the heat transfer path between each of the infrared detecting thermal element 20 and the temperature compensating thermal element 30 and the external environment is thermally conductive is satisfied, the shape and size of the cavities 91 and 92 are determined. , And the thickness of the thin portions 14 and 15 may be the same or different. Here, “thermally symmetric” does not necessarily mean geometric symmetry, but means the symmetry of the heat transfer path in consideration of thermal resistance. Thus, by forming each of the infrared detecting thermal element 20 and the temperature compensating thermal element 30 in the thin portions 14 and 15 (in other words, the cavities 91 and 92) having a heat capacity smaller than the heat capacity of the substrate 11, Since the resistance values of the heat sensitive films 22 and 32 change sensitively even with a small amount of heat, the sensitivity characteristics of the infrared temperature sensor 100 can be improved. Further, by forming each of the infrared detecting thermal element 20 and the temperature compensating thermal element 30 in the thin portions 14 and 15 arranged symmetrically in heat conduction with respect to the external environment, the response speed of the infrared detecting thermal element 20 and The response speed of the temperature compensating thermal element 30 can be made substantially the same, and the response stability of the infrared temperature sensor 100 can be improved. The present embodiment is not limited to the above-described sensor structure. For example, each of the infrared detection thermal element 20 and the temperature compensation thermal element 30 is a single thin portion having a heat capacity smaller than the heat capacity of the substrate 11. (In other words, a single cavity), and includes a sensor structure in which each of the infrared detecting thermal element 20 and the temperature compensating thermal element 30 is symmetrically disposed in a thermally conductive manner with respect to the external environment.

  The substrate 11 preferably has a thick portion 17 between the infrared detecting thermal element 20 and the temperature compensating thermal element 30. The thick portion 17 is thicker than the thin portions 14 and 15 and has a thickness equal to or less than the maximum thickness of the substrate 11. As a result, the thermal resistance between the cavities 91 and 92 can be increased, and a decrease in temperature measurement accuracy due to the flow of heat between the cavities 91 and 92 can be suppressed. Further, as shown in FIG. 2, the projected area in the thickness direction of the substrate 11 of the infrared absorption film 70 is preferably smaller than the projected area in the thickness direction of the substrate 11 of the thin portion 14. That is, when the infrared absorption film 70 is projected on the substrate 11 (more specifically, the insulating film 12) in the thickness direction of the substrate, the projected area is arranged on the inner side of the thin portion 14. As a result, the amount of heat absorbed by the infrared absorption film 70 can be confined inside the cavity 91 without leaking to the substrate 11 as much as possible, so that the sensitivity characteristics of the infrared detecting thermal element 20 can be improved. The projected area of the infrared reflecting film 80 in the thickness direction of the substrate 11 is preferably larger than the projected area of the thin portion 15 in the thickness direction of the substrate 11. That is, when the infrared reflecting film 80 is projected on the substrate 11 (more specifically, the insulating film 12) in the thickness direction of the substrate, the thin portion 15 is disposed on the inner side of the projected area. As a result, since the heat quantity from the infrared rays can flow directly into the substrate having a large heat capacity so that it does not flow into the cavity 92 as much as possible, the temperature compensation thermal element 30 can accurately detect the heat quantity from the external environment. The common electrode 50 is preferably disposed between the infrared detecting thermal element 20 and the temperature compensating thermal element 30. Since the common electrode 50 is excellent in heat conduction, heat dissipation can be improved. The protective film 13 is preferably made of the same material as the insulating film 12. Thereby, since each of the infrared detecting thermal element 20 and the temperature compensating thermal element 30 can be surrounded by the same material thin film from above and below, uniform heat conduction characteristics can be obtained. The fixed resistance elements 41 and 42 are not necessarily formed on the substrate 11 together with the infrared detecting thermal element 20 and the temperature compensating thermal element 30, and may be formed on another substrate.

  Next, the manufacturing process of the infrared temperature sensor 100 will be described with reference to FIGS. First, as shown in FIG. 3, a (100) silicon substrate is prepared as the substrate 11, and a silicon oxide film is formed as an insulating film 12 on the first main surface 11 </ b> A and the second main surface 11 </ b> B of the substrate 11. In order to form the silicon oxide film, for example, a thermal oxidation method or the like may be applied. The film thickness of the insulating film 12 may be adjusted to such an extent that insulation with the substrate 11 is ensured, and for example, about 0.1 μm to 0.5 μm is preferable. Next, the individual electrodes 21 and 31, the common electrode 50, and the fixed resistance elements 41 and 42 are formed on the insulating film 12 on the first main surface 11A. In order to form the individual electrodes 21 and 31 and the common electrode 50, for example, a metal thin film of about 150 nm to 600 nm is deposited on the insulating film 12 using an RF magnetron sputtering method or the like, an etching mask is formed by photolithography, The metal thin film may be processed into a predetermined electrode shape by dry etching such as reactive ion etching or ion milling. In order to improve the adhesion between the metal thin film and the insulating film 12, it is preferable to interpose an adhesion layer such as titanium (Ti).

  Next, as shown in FIG. 4, a composite metal oxide film as the heat sensitive films 22 and 32 is deposited on the individual electrodes 21 and 31 and the common electrode 50 by sputtering, and the composite metal oxide film is formed into a predetermined shape by wet etching. Pattern. Through the above steps, the infrared detecting thermal element 20 and the temperature compensating thermal element 30 are formed on the insulating film 12. Subsequently, a silicon oxide film as a protective film 13 is formed on the entire surface of the substrate with a film thickness of about 0.3 μm to 2 μm by TEOS-CVD, an etching mask is formed by photolithography, and then the silicon oxide film is wet etched. To selectively remove the portions where the output terminal electrodes 51 and 52 and the extraction electrode 54 are to be formed. Then, an aluminum electrode as the output terminal electrodes 51 and 52 and the extraction electrode 54 is formed to about 1 μm by EB vapor deposition, and unnecessary portions of the aluminum electrode are removed by lift-off.

Next, as shown in FIG. 5, gold (Au) as the infrared reflecting film 80 is formed on the protective film 13 by sputtering, and the opening region of the cavity 92 (projection of the thin portion 15 in the thickness direction of the substrate 11). Unnecessary portions of the infrared reflecting film 80 are removed using a lift-off method so that the outer edge of the infrared reflecting film 80 is positioned outside a predetermined distance (for example, 20 μm) of the outer edge of the region. Next, the opening of the cavity 91 is arranged so that the outer edge of the infrared absorption film 70 is located inside a predetermined distance (for example, 20 μm) of the outer edge of the opening area of the cavity 91 (projection area of the thin portion 14 in the thickness direction of the substrate 11). Using a shadow mask having an opening smaller than the region, Au black is heated and evaporated on the protective film 13 to form an infrared absorption film 70. Finally, after an etching mask is formed on the second main surface 11B side of the substrate 11 by photolithography, the substrate 11 is made to be second main ion by reactive ion etching such as D-RIE method using fluoride gas. Deep digging perpendicular to the surface 11B, the cavities 91 and 92 are opened. The D-RIE method is mainly for suppressing chemical side etching caused by F radicals by depositing a reaction inhibiting film (fluorocarbon-based polymer) on the sidewalls of the cavities 91 and 92 using C ₄ F ₈ gas. Plasma etching for anisotropically etching the substrate 11 substantially vertically by a plasma deposition step and chemical etching of the substrate 11 with F radicals using SF ₆ gas and physical etching of the reaction suppression film with F ions. This is a method of deepening the substrate 11 by repeating the steps alternately.

  Next, a comparison result between Examples 1, 2, and 3 and Comparative Example 1 will be described.

[Example 1]
The infrared temperature sensor 100 according to Example 1 shown in FIG. 5 was manufactured by the following procedure. First, a (100) silicon substrate was prepared as the substrate 11, and a thermal insulating film as an insulating film 12 was formed to a thickness of 0.5 μm on the substrate surface. Next, Pt / Ti was formed on the insulating film 12 by sputtering and processed into a predetermined electrode shape by dry etching, thereby forming the individual electrodes 21 and 31 and the common electrode 50. Next, 0.4 μm of MnNiCo-based oxide is deposited on the individual electrodes 21 and 31 and the common electrode 50 under sputtering conditions of a substrate temperature of 600 ° C., a deposition pressure of 0.5 Pa, an O ₂ / Ar flow rate ratio of 1%, and an RF power of 400 W. Deposition to some extent. Thereafter, the MnNiCo-based oxide film is heat-treated at 650 ° C. for 1 hour in an air atmosphere using a baking furnace, and processed into a predetermined shape by wet etching using a ferric chloride aqueous solution, so that the target resistance value is 140 kΩ (room temperature ) Heat-sensitive films 22 and 32 were formed. Next, the protective film 13 having a thickness of about 0.5 μm was formed by TEOS-CVD, and the aluminum electrodes as the output terminal electrodes 51 and 52 and the extraction electrode 54 were formed by about 1 μm by the EB vapor deposition method. Subsequently, about 0.1 μm of gold (Au) as the infrared reflecting film 80 was formed by sputtering, and about 5 μm of Au black as the infrared absorbing film 70 was formed by heating vapor deposition. Finally, the substrate 11 was deepened substantially vertically by the D-RIE method to form cavities 91 and 92 that were thermally conductive with respect to the external environment. The infrared temperature sensor 100 manufactured as described above was irradiated with infrared rays from a tungsten lamp, and the respective resistance changes of the infrared detection thermal element 20 and the temperature compensation thermal element 30 were measured. When a pulse wave of 5.0 V for 1 second was irradiated, the resistance value of the thermal element 20 for infrared detection changed from 140 kΩ to 91.49 kΩ. The temperature change converted from this resistance value change was 10.74 ° C. On the other hand, the resistance value of the temperature compensating thermosensitive element 30 changed from 140 kΩ to 134.25 kΩ. The temperature change converted from this resistance value change was 1.33 ° C. The 90% response changes of the infrared detecting thermal element 20 and the temperature compensating thermal element 30 were 110 msec and 108 msec, respectively. By outputting these resistance value changes as voltage changes from the full bridge circuit, a 90% response of 110 msec and an output voltage (unbalanced voltage between the output terminal electrodes 51 and 52) of 471.5 mV were obtained.

[Example 2]
The infrared temperature sensor according to the second embodiment is different from the infrared temperature sensor 100 according to the first embodiment in that it does not have the infrared absorption film 70, and is common in other points. The infrared temperature sensor according to Example 2 was irradiated with infrared rays from a tungsten lamp, and the respective resistance changes of the infrared detecting thermal element 20 and the temperature compensating thermal element 30 were measured. When the pulse wave of 5.0 V and 1 second was irradiated, the resistance value of the infrared detecting thermal element 20 changed from 140 kΩ to 115.2 kΩ. The temperature change converted from this resistance value change was 5.74 ° C. On the other hand, the resistance value of the temperature compensating thermosensitive element 30 changed from 140 kΩ to 134.25 kΩ. The temperature change converted from this resistance value change was 1.33 ° C. The 90% response changes of the infrared detecting thermal element 20 and the temperature compensating thermal element 30 were 95 msec and 108 msec, respectively. By outputting these resistance value changes as voltage changes from the full bridge circuit, a 90% response of 108 msec and an output voltage of 190.5 mV were obtained. As compared with the infrared temperature sensor 100 according to the first embodiment, it can be understood that the sensitivity of the infrared temperature sensor according to the second embodiment is low.

[Example 3]
The infrared temperature sensor according to the third embodiment is different from the infrared temperature sensor 100 according to the first embodiment in that it does not have the infrared reflection film 80, and is common in the remaining points. The infrared temperature sensor according to Example 3 was irradiated with infrared rays from a tungsten lamp, and resistance changes of the infrared detection thermal element 20 and the temperature compensation thermal element 30 were measured. When a pulse wave of 5.0 V for 1 second was irradiated, the resistance value of the thermal element 20 for infrared detection changed from 140 kΩ to 91.49 kΩ. The temperature change converted from this resistance value change was 10.74 ° C. On the other hand, the resistance value of the temperature compensating thermosensitive element 30 was changed from 140 kΩ to 115.2 kΩ. The temperature change converted from this resistance value change was 5.74 ° C. The 90% response changes of the infrared detecting thermal element 20 and the temperature compensating thermal element 30 were 110 msec and 95 msec, respectively. By outputting these resistance value changes as voltage changes from the full bridge circuit, a 90% response of 110 msec and an output voltage of 280.9 mV were obtained. Compared with the infrared temperature sensor 100 according to the first embodiment, it can be understood that the sensitivity of the infrared temperature sensor according to the third embodiment is low.

[Comparative Example 1]
The infrared temperature sensor according to Comparative Example 1 is different from the infrared temperature sensor 100 according to Example 1 in that it does not have the cavities 91 and 92, and is common in the remaining points. In the same manner as in Examples 2 and 3, the infrared temperature sensor according to Comparative Example 1 is irradiated with infrared rays from a tungsten lamp, and the resistance changes of the infrared detecting thermal element 20 and the temperature compensating thermal element 30 are applied to the voltage from the full bridge circuit. Although output as a change, the output voltage was only 7.5 mV. Compared with the infrared temperature sensor 100 according to Example 1, it can be understood that the sensitivity of the infrared temperature sensor according to Comparative Example 1 is extremely low and cannot be used practically.

[Embodiment 2]
FIG. 6 is a cross-sectional view of the infrared temperature sensor 200 according to the present embodiment. The infrared temperature sensor 200 is different from the infrared temperature sensor 100 in that the infrared reflective film 80 is connected to the common electrode 50 via the extraction electrode 54, and the other points are common. The infrared temperature sensor 200 was irradiated with infrared rays from a tungsten lamp, and the respective resistance changes of the infrared detecting thermal element 20 and the temperature compensating thermal element 30 were measured. When a pulse wave of 5.0 V for 1 second was irradiated, the resistance value of the thermal element 20 for infrared detection changed from 140 kΩ to 91.49 kΩ. The temperature change converted from this resistance value change was 10.74 ° C. On the other hand, the resistance value of the temperature compensating thermosensitive element 30 was changed from 140 kΩ to 136.12 kΩ. The temperature change converted from this resistance value change was 0.83 degreeC. The 90% response changes of the infrared detecting thermal element 20 and the temperature compensating thermal element 30 were 110 msec and 108 msec, respectively. By outputting these resistance value changes as voltage changes from the full bridge circuit, a 90% response of 110 msec and an output voltage of 488 mV were obtained. By connecting the infrared reflection film 80 to the common electrode 50 via the extraction electrode 54, the amount of infrared heat can be efficiently radiated from the infrared reflection film 80 to the outside via the extraction electrode 54. The influence which the element 30 receives from infrared rays can be reduced, and the sensitivity characteristic of the infrared temperature sensor 200 can be improved. The present embodiment is not limited to the sensor structure shown in FIG. 6. For example, the infrared reflection film 80 may be connected to the output terminal electrode 52, or the infrared reflection film 80 may be connected via the extraction electrode 54. May be connected to the common electrode 50 and the infrared reflective film 80 may be connected to the output terminal electrode 52. Similar effects can be obtained even in such a sensor structure.

[Embodiment 3]
FIG. 7 is a cross-sectional view of the infrared temperature sensor 300 according to the present embodiment. The infrared temperature sensor 300 is a first sensor between the infrared detection thermal element 20 and the extraction electrode 54 (or the common electrode 50) or between the temperature compensation thermal element 30 and the extraction electrode 54 (or the common electrode 50). It differs from the infrared temperature sensor 100 in that a recess 13A that is depressed on the main surface 11A side is formed in the protective film 13, and the other points are common. By forming the recess 13A in the protective film 13 in this manner, the thermal resistance between the cavities 91 and 92 can be increased, and the heat conduction from one cavity can be prevented from affecting the temperature of the other cavity. In order to further enhance the heat shielding between the cavities 91 and 92, it is preferable to form the recess 13A in a closed curve so as to surround the outer edges of the infrared detecting thermal element 20 and the temperature compensating thermal element 30.

[Embodiment 4]
FIG. 8 is a cross-sectional view of an infrared temperature sensor 400 according to this embodiment. The infrared temperature sensor 400 includes an infrared absorption film 71 that covers at least a part of the temperature-compensating thermosensitive element 30 via the protective film 13, an infrared reflection film 81 that covers at least a part of the infrared absorption film 71, and a protective film. 13 is different from the infrared temperature sensor 100 in that it includes an infrared reflection film 82 that covers at least a part of the infrared detecting thermal element 20 and an infrared absorption film 72 that covers at least a part of the infrared reflection film 82. The other points are the same. According to such a device structure, the heat capacity of the laminated structure composed of the infrared absorbing film 71 and the infrared reflecting film 81 and the heat capacity of the laminated structure composed of the infrared reflecting film 82 and the infrared absorbing film 72 can be adjusted substantially the same. Each of the infrared detecting thermal element 20 and the temperature compensating thermal element 30 can equalize the influence of heat received from the external environment.

[Embodiment 5]
The sensor structures of Embodiments 1 to 4 described above can be combined with each other, and the present invention includes such combinations.

  The infrared temperature sensor according to the present invention can be used in various applications for non-contact measurement of the temperature of a heat source.

100, 200, 300, 400 ... Infrared temperature sensor 11 ... Substrate 12 ... Insulating film 13 ... Protective film 14, 15 ... Thin portion 16 ... Maximum thickness portion 17 ... Thick portion 20 ... Infrared detection thermal element 30 ... Temperature compensation Thermal element 41, 42 ... Fixed resistance element 50 ... Common electrode 51, 52 ... Output terminal electrode 53 ... Input terminal electrode 70 ... Infrared absorbing film 80 ... Infrared reflecting film 91, 92 ... Cavity

Claims (6)

An infrared temperature sensor for non-contact measurement of the temperature of the heat source,
A thermosensitive element for detecting infrared rays for detecting the amount of infrared rays emitted from the heat source; and
A temperature-compensating thermal element that detects the amount of heat from the external environment;
A first main surface on which the infrared detecting thermal element and the temperature compensating thermal element are disposed and a substrate having a second main surface which is the back surface thereof,
The infrared detecting thermal element and the temperature compensating thermal element are arranged in a thin part thinner than the maximum thick part of the substrate,
The substrate has a thick part thicker than the thin part between the infrared detecting thermal element and the temperature compensating thermal element,
The thin part where the infrared detecting thermal element and the temperature compensating thermal element are arranged, and the pair of thermal films which the infrared detecting thermal element and the temperature compensating thermal element arranged in the thin part have, The same shape and the same area, arranged symmetrically with the thick part in between,
A common electrode of the infrared detecting thermal element and the temperature compensating thermal element is formed on the first main surface on the thick portion between the infrared detecting thermal element and the temperature compensating thermal element,
An infrared reflection film covering at least a part of the temperature-compensating thermosensitive element;
The infrared temperature sensor, wherein a projected area of the infrared reflecting film in the thickness direction of the substrate is larger than a projected area of the thin portion in the thickness direction of the substrate. The infrared temperature sensor according to claim 1 ,
An infrared temperature sensor, further comprising a protective film that covers the infrared detecting thermal element and the temperature compensating thermal element. The infrared temperature sensor according to claim 1 or 2 ,
A first infrared absorbing film covering at least a part of the temperature-compensating thermosensitive element;
A first infrared reflecting film covering at least a part of the first infrared absorbing film;
A second infrared reflective film covering at least a part of the infrared detecting thermal element;
A second infrared absorbing film covering at least a part of the second infrared reflecting film;
An infrared temperature sensor further comprising: The infrared temperature sensor according to claim 1 or 2 ,
An infrared absorbing film covering at least a part of the infrared detecting thermal element;
An infrared temperature sensor, wherein a projected area of the infrared absorbing film in the thickness direction of the substrate is smaller than a projected area of the thin portion in the thickness direction of the substrate. The infrared temperature sensor according to claim 2 ,
The infrared reflection film is connected to at least one of an output terminal electrode of the temperature compensation thermal element or a common electrode of the infrared detection thermal element and the temperature compensation thermal element. The infrared temperature sensor according to claim 1 ,
Further comprising a protective film covering the infrared detecting thermal element and the temperature compensating thermal element, the protective film between the infrared detecting thermal element and the common electrode, or the temperature compensating thermal element and the An infrared temperature sensor having a concave portion that is depressed on the first main surface side with a common electrode.

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