TW201349284A - Infrared emitting device - Google Patents

Abstract

This infrared ray radiating element includes: a substrate; a functional layer having a heat-releasing body layer formed at a first surface side of the substrate and a protection layer covering the heat-releasing body layer; an insulating layer that supports the functional layer and that is interposed between the first surface and the functional layer; and a pair of pads that are formed at the first surface side and are electrically connected to the heat-releasing body layer. The substrate has an opening section at which, seen from the heat-releasing body layer side, a portion of the surface at the reverse side of the insulating layer is exposed. The insulating layer has: a diaphragm section that separates the opening section and the heat-releasing body layer; and a support section that supports the diaphragm section and is provided to the first surface side at the periphery of the opening section of the substrate. The insulating layer and the protection layer comprise a material having a coefficient of linear expansion that is closer to that of the heat-releasing body layer than to that of the pads.

Description

Infrared radiation element

The invention relates to infrared radiation elements.

In the past, research and development have been carried out on infrared radiation elements manufactured by manufacturing techniques using MEMS (micro electro mechanical systems). Such an infrared radiation element can be used as an infrared source (infrared light source) such as a gas sensor and an optical analysis device.

For example, the radio frequency source of the infrared radiation element is, for example, the one shown in Fig. 9 and Fig. 10 (Japanese Patent Application No. 9-184757 (hereinafter referred to as "Document 1").

The radiation source includes a substrate 13, a first insulating layer 22 formed on the substrate 13, a radiation surface layer 11 formed on the first insulating layer 22, a second insulating layer 24 formed on the radiation surface layer 11, and An ultrafine plurality of incandescent filaments 10 formed on the second insulating layer 24. Further, the radiation source includes a third insulating layer 26 formed to cover the plurality of incandescent filaments 10 to protect the plurality of incandescent filaments 10, and a pair of metal pads 15 and 15 connected through the openings formed in the third insulating layer 26. At the two ends of each of the white hot filaments 10. The second insulating layer 24 is disposed for the purpose of electrically insulating the radiation surface layer 11 and the plurality of incandescent filaments 10. Further, as described in the document 1, the incandescent filament 10 is composed of other elements (the first insulating layer 22, the radiation surface layer 11, the second insulating layer 24, and the third insulating layer 26) which are formed into a multilayer structure of a uniform planar plate. surround. Further, in the gist of the document 1, the purpose of disposing the first insulating layer 22 and the third insulating layer 26 is to protect the white The hot filament 10 and the radiation preventing surface layer 11 are not oxidized.

Further, on the substrate 13, an opening portion 14 is formed corresponding to the radiation surface layer 11. In Document 1, it is described that an aqueous solution of potassium hydroxide (KOH), an aqueous solution of ethylenediamine in which a small amount of pyrocatechol is added, and tetramethylammonium hydroxide (TMAH) can be used as the etching liquid for forming the opening 14.

The substrate 13 is formed of a (100) aligned silicon wafer. The first insulating layer 22 is made of a tantalum nitride layer having a thickness of 200 nm. The radiation surface layer 11 is composed of a polycrystalline germanium film having a thickness of about 1 μm and doped with boron, phosphorus, or arsenic. The second insulating layer 24 is made of a tantalum nitride layer having a thickness of about 50 nm. The plurality of incandescent filaments 10 are composed of a tungsten layer having a thickness of about 400 nm. The third insulating layer 26 is made of a tantalum nitride layer having a thickness of about 200 nm. The metal pad 15 is formed, for example, of aluminum, and is in electrical resistance contact with the plurality of incandescent filaments 10 through openings formed in the third insulating layer 26.

Further, the radiation source, the radiation surface layer 11 has an area of 1 mm ² . The size of the incandescent filament 10, for example, each of the incandescent filaments 10 has a thickness of 0.1 to 1 μm and a width of 2 to 10 μm, and the plurality of incandescent filaments 10 are arranged at intervals of 20 to 50 μm.

The radioactive source, the plurality of incandescent filaments 10 are heated by the current flowing through the incandescent filaments 10. However, the plurality of incandescent filaments 10 are specifically used to heat the radiation surface layer 11, and the radiation surface layer 11 is the main heat source. .

However, when the infrared radiation element is used as an infrared source for a spectroscopic gas sensor, the infrared radiation element is intermittently driven to intermittently emit infrared rays, and the lock-in amplifier is used to increase the amplitude of the light-receiving element for detecting infrared rays. The output, which increases the S/N ratio of the output of the gas sensor, is well known.

However, the configuration of the radiation source shown in FIGS. 9 and 10 is not limited to the heat capacity of the incandescent filament 10, the first insulating layer 22, the radiation surface layer 11, the second insulating layer 24, and the third insulating layer. The heat capacity of 26, relative to the voltage waveform of the white heat filament 10, the temperature of the radiation surface layer 11 The response to change is later. Therefore, in the case of the radiation source, the temperature of the radiation surface layer 11 is hard to rise, and it is difficult to achieve high output, low power consumption, and high speed of response.

Therefore, in order to reduce the heat capacity of the first insulating layer 22 in the radiation source, the thickness of the first insulating layer 22 should be made thin. However, in the case of the radiation source, there is a fear that the thermal stress generated during the operation is likely to cause the first insulating layer 22 to be easily damaged. Further, in the case of the radiation source, there is a fear that the second insulating layer 24 is easily broken due to the stress generated by the difference in linear expansion coefficient between the incandescent filament 10 and the second insulating layer 24.

In view of the above, an object of the present invention is to provide an infrared radiation element which can achieve low power consumption and high output, and can improve reliability.

The infrared radiation element (1) of the present invention includes a substrate (2) and a functional layer (5) having a heat generating layer (3) formed on one surface (20) side of the substrate (2) and covering the heat a protective layer (4) of the bulk layer (3); an insulating layer (6) interposed between the surface (20) of the substrate (2) and the functional layer (5) for supporting the functional layer (5) And a pair of spacers (9, 9) electrically connected to the heat generating body layer (3) formed on the surface (20) side of the substrate (2). The infrared radiation element (1) emits infrared rays from the heating element layer (3) by energizing the heating element layer (3). The substrate (2) includes an opening (2a) when viewed from the side of the heating element layer (3), and exposes a part (6a) of the surface on the opposite side of the insulating layer (6). The insulating layer (6) includes a diaphragm portion (6D) for isolating the opening portion (2a) from the heating element layer (3); and a supporting portion (6S) disposed at the opening of the substrate (2) The surface (20) side around the portion (2a) is for supporting the diaphragm portion (6D). The insulating layer (6) and the protective layer (4) are made of a material having a linear expansion coefficient closer to the heating element layer (3) than the spacers (9, 9).

In one embodiment, each of the spacers (9) is disposed near the boundary between the diaphragm portion (6D) and the support portion (6S).

In one embodiment, a wiring portion (8, 8) electrically connected to the heating element layer (3) and each of the spacers (9, 9) is provided, and the wiring portion (8) is provided with a ratio of the pad The sheet (9) is composed of a wiring material which is closer to the linear expansion coefficient of the heating body layer (3).

In one embodiment, a wiring portion (8, 8) electrically connected to the heating element layer (3) and each of the spacers (9, 9) is provided, and the wiring portion (8) is formed by the heating element layer (3) The same material is formed.

In one embodiment, the functional layer (5) has a stress relieving structure (50).

In one embodiment, the stress relieving structure (50) is formed by penetrating at least one slit (51) of the protective layer (4) and the heating element layer (3).

In one embodiment, the slit (51) has an elongated shape that is longitudinally parallel to a direction in which the pair of spacers (9, 9) are disposed in a direction.

In one embodiment, the stress relieving structure (50) is formed by a cut-in groove (52) formed on a periphery of the heat generating layer (3).

The infrared radiation element of the present invention can achieve low power consumption and high output, and can improve reliability.

1‧‧‧Infrared emitting elements

2‧‧‧Substrate

2a‧‧‧ openings

3‧‧‧Fever body layer

4‧‧‧Protective layer

5‧‧‧ functional layer

6‧‧‧Insulation

6a‧‧‧ surface

6D‧‧‧diaphragm department

6S‧‧‧Support Department

8‧‧‧Wiring Department

9‧‧‧shims

10‧‧‧White hot filament

11‧‧‧radiation surface layer

13‧‧‧Substrate

14‧‧‧ openings

15‧‧‧Metal pad

20‧‧‧1st

21‧‧‧2nd

22‧‧‧1st insulation layer

24‧‧‧2nd insulation layer

26‧‧‧3rd insulation layer

50‧‧‧stress mitigation structure

51‧‧‧Slit

52‧‧‧cut into the ditch

Further embodiments of the invention are described in further detail. Other features and advantages of the present invention will become apparent from the following detailed description and appended claims.

1A is a schematic plan view of an important part of an infrared radiation element according to Embodiment 1 of the present invention, and FIG. 1B is a schematic cross-sectional view of the infrared radiation element of Embodiment 1.

2A is a schematic plan view of an important part of the infrared radiation element according to Embodiment 2 of the present invention, and FIG. 2B is a schematic cross-sectional view of the infrared radiation element of Embodiment 2.

Fig. 3 is a schematic plan view showing important parts of another configuration example of the infrared radiation element of the second embodiment.

Fig. 4 is a schematic plan view showing important parts of another configuration example of the infrared radiation element of the second embodiment.

5A is a schematic plan view of an important part of an infrared radiation element according to Embodiment 3 of the present invention, and FIG. 5B is a schematic cross-sectional view of the infrared radiation element of Embodiment 3.

Fig. 6 is a schematic plan view showing another configuration example of the infrared radiation element of the third embodiment.

Fig. 7 is a schematic plan view showing important parts of the infrared radiation element according to Embodiment 4 of the present invention.

Fig. 8 is a schematic plan view showing important parts of another configuration example of the infrared radiation element of the fourth embodiment.

Figure 9 is a plan view of a conventional example of a radiation source.

Figure 10 is a cross-sectional view of the A-A of the radiation source of Figure 9.

[Best Mode for Carrying Out the Invention] (Embodiment 1)

Hereinafter, the infrared radiation element 1 of the present embodiment will be described with reference to FIGS. 1A and 1B.

The infrared radiation element 1 includes a substrate 2 having a first surface 20 and a second surface 21, and a functional layer 5 having a heating element layer 3 and a heating element layer 3 formed on one surface (first surface 20) side of the substrate 2. The protective layer 4 and the insulating layer 6 are located on the first surface 20 side of the substrate 2 and interposed between the substrate 2 and the functional layer 5 for supporting the functional layer 5. Moreover, the illustration of the protective layer 4 is omitted in FIG. 1A.

Further, the infrared radiation element 1 includes a pair of spacers 9 and 9 formed on the first surface 20 side of the substrate 2 and electrically connected to the heating element layer 3, and is electrically connected to the heating element layer 3 to be radiated from the heating element layer 3. infrared.

When the substrate 2 is viewed from the side of the heat generating body layer 3, the opening 2a is formed, and a part of the surface on the opposite side of the insulating layer 6 (the central portion of the first and first FIGS. 1A and 1B) is exposed. Specifically, the substrate 2 has a through hole for the purpose of forming the opening 2 a, and the opening surface of the through hole of the first surface 20 is closed by the insulating layer 6 formed on the first surface 20 .

Further, the infrared radiation element 1 includes wiring portions 8 and 8, and is electrically connected to the heating element layer 3 and the spacers 9 and 9, respectively. In the example of FIGS. 1A and 1B, both ends of the heating element layer 3 having a square shape are electrically connected to the spacers 9 and 9 via the wiring portions 8 and 8, respectively.

Hereinafter, each component of the infrared radiation element 1 will be described in detail.

The substrate 2 is formed of a single crystal germanium substrate having a (100) plane on the first surface 20, but is not limited thereto, and may be formed of a single crystal germanium substrate of a (110) plane. Further, the substrate 2 is not limited to a single crystal germanium substrate, and may be a polycrystalline germanium substrate or a germanium substrate. The material of the substrate 2 is preferably a material having a thermal conductivity and a heat capacity larger than that of the insulating layer 6.

The outer peripheral shape of the substrate 2 is a right-angled quadrilateral (for example, square or rectangular). The outer shape of the substrate 2 is not particularly limited. However, for example, it is preferably set to 10 mm□ or less (10 mm×10 mm or less). Further, in the substrate 2, the opening shape of the opening portion 2a is a right-angled quadrangle (for example, a square or a rectangle). The opening 2a of the substrate 2 is formed such that the opening area on the other surface (second surface 21) side is larger than the one surface (first surface 20) side. Here, the opening 2a of the substrate 2 is formed in a shape in which the opening area gradually increases as it leaves the insulating layer 6. The opening 2a of the substrate 2 is formed by etching the substrate 2. When the substrate 2 is a single crystal germanium substrate having the first surface 20 as a (100) plane, the opening 2a of the substrate 2 can be formed by an anisotropic etching using an alkali solution as an etching liquid. The opening shape of the opening 2a of the substrate 2 is not particularly limited. Further, in the infrared radiation element 1 , when the mask layer when the opening 2 a is formed is formed of an inorganic material, the mask layer may remain on the second surface 21 side of the substrate 2 . Further, as the mask layer, for example, a laminated film of a tantalum oxide film and a tantalum nitride film may be used.

The insulating layer 6 is composed of a diaphragm portion 6D for isolating the opening portion 2a and the heating element layer 3; and a supporting portion 6S formed on the first surface 20 side around the opening portion 2a of the substrate 2 for supporting the diaphragm portion 6D; Composition.

Further, the insulating layer 6 is composed of a tantalum oxide film on the substrate 2 side and a tantalum nitride film laminated on the opposite side surface of the tantalum oxide film when viewed from the substrate 2 side. The insulating layer 6 is not limited to a laminated film of a tantalum oxide film and a tantalum nitride film. For example, it may be a single layer structure of a tantalum oxide film or a tantalum nitride film, or may be a single layer structure composed of other materials. Or a laminated structure of two or more layers.

In the production of the infrared radiation element 1, the insulating layer 6 also has an function of etching the barrier layer when the substrate 2 is etched by the second surface 21 side of the substrate 2 to form the opening 2a.

The heating body layer 3 has a rectangular shape (for example, a square or a rectangular shape), but is not particularly limited to a rectangular shape, and may be, for example, a circular shape or a polygonal shape.

The planar size of the heating body layer 3 is preferably set to be smaller than the plane dimension of the surface 6a facing the opening portion 2a in the insulating layer 6. That is, the heating body layer 3 is preferably set to be smaller than the planar size of the diaphragm portion 6D. Here, the planar size of the diaphragm portion 6D is not particularly limited. However, for example, it is preferably set to 5 mm□ or less (5 mm×5 mm or less).

The planar size of the heating element layer 3 is preferably set to be 3 mm □ or less (3 mm × 3 mm or less). However, the planar shape of the heating element layer 3 is not limited to a square shape, and may be, for example, a rectangular shape, a circular shape, a polygonal shape or the like.

The material of the heating body layer 3 is tantalum nitride. That is, the heating body layer 3 is composed of a tantalum nitride layer. The material of the heating body layer 3 is not limited to tantalum nitride. For example, titanium nitride or the like may be used. Further, as the material of the heating body layer 3, a conductive polysilicon may be used. That is, the heating body layer 3 may be composed of a conductive polysilicon layer. In the heat generating layer 3, from the viewpoint of high temperature, chemical stability, and ease of design of surface resistance, it is preferable to use a tantalum nitride layer or a conductive polysilicon layer. The tantalum nitride layer can change the surface resistance by changing its composition. The conductive polysilicon layer can be changed in surface resistance by changing the impurity concentration or the like. The conductive polycrystalline germanium layer may be composed of an n-type polycrystalline germanium layer or a p-type polycrystalline germanium layer doped with a high concentration of n-type impurities or p-type impurities. When the n-type polycrystalline germanium layer is used as the conductive polysilicon layer, and the n-type impurity is, for example, phosphorus, for example, the impurity concentration may be appropriately set within a range of about 1×10 ¹⁸ cm ⁻³ to 5×10 ²⁰ cm ⁻³ . . Further, when the p-type polycrystalline germanium layer is used as the conductive polysilicon layer, and the p-type impurity is, for example, boron, for example, the impurity concentration is appropriately set to the range of about 1 × 10 ¹⁸ cm ^-3 to 1 × 10 ²⁰ cm ^-3 . Just fine.

In the infrared radiation element 1, the peak wavelength λ of the infrared ray emitted from the heating element layer 3 is determined by the temperature of the heating element layer 3. Here, if the absolute temperature of the heating element layer 3 is T [K] and the peak wavelength is λ [μm], the peak wavelength λ, λ = 2898 / T

The relationship between the absolute temperature T of the heating element layer 3 and the peak wavelength λ of the infrared ray emitted by the heating element layer 3 satisfies the displacement law of Vienna. Therefore, in the infrared radiation element 1, the heat generating body layer 3 constitutes a black body. The infrared radiation element 1 can change the Joule heat generated in the heating element layer 3 by adjusting the input power supplied between the pair of spacers 9 and 9 by an external power source (not shown), and the heating element layer 3 can be changed. The temperature changes. Therefore, the infrared radiation element 1 can change the temperature of the heating element layer 3 in accordance with the input power to the heating element layer 3, and the peak wavelength of the infrared ray emitted by the heating element layer 3 can be changed by the temperature change of the heating element layer 3. λ produces a change. Further, in the infrared radiation element 1 of the present embodiment, the temperature of the heat generating layer 3 can be increased to increase the amount of infrared radiation. Therefore, the infrared radiation element 1 can be used as a high-output infrared light source in a wide range of infrared wavelength regions. For example, when the infrared radiation element 1 is used as an infrared light source of a gas sensor, the peak wavelength λ of the infrared ray emitted from the heating element layer 3 is preferably 4 μm, and the temperature of the heating element layer 3 is set to 800 K. can. Here, in the infrared radiation element 1 of the present embodiment, the heating element layer 3 constitutes a black body as described above. Thereby, the infrared radiation element 1 estimates that the total energy E emitted per unit area of the heating element layer 3 per unit time is approximately proportional to T ⁴ (that is, it is estimated that it is satisfied with the Steffen-Bozemann law).

The protective layer 4 is composed of a tantalum nitride film. The protective layer 4 is not limited thereto. For example, it may be composed of a tantalum oxide film, or may have a laminated structure of a tantalum oxide film and a tantalum nitride film. Guarantee When the protective layer 4 is energized to the heating element layer 3, the desired wavelength of the heating element layer 3 and the transmittance of the infrared ray to the wavelength region are preferably as high as possible. However, the transmittance is not necessarily 100%.

In the infrared radiation element 1, the stress balance of the sandwich structure composed of the insulating layer 6, the heating element layer 3, and the protective layer 4 is considered, and the material and thickness of the insulating layer 6 and the protective layer 4 are preferably set. Thereby, the infrared radiation element 1 can improve the stress balance of the sandwich structure, suppress the warpage and breakage of the sandwich structure, and further improve the mechanical strength. Further, as shown in FIG. 1B, the protective layer 4 may cover at least the heat generating layer 3 and the region of the wiring portion 8 on which the spacer 9 is not overlapped. However, the protective portion 6 is also formed in the support portion 6S of the insulating layer 6. The area where the spacer 9 is not formed is more preferable.

The thickness of the heat generating body layer 3 is preferably 0.2 μm or less from the viewpoint of reducing the heat capacity of the heat generating body layer 3.

The thickness of the insulating layer 6 , the thickness of the heat generating layer 3 , and the total thickness of the protective layer 4 are, for example, a viewpoint of reducing the heat capacity of the laminated structure of the insulating layer 6 , the heat generating layer 3 , and the protective layer 4 . It is preferably in the range of about 0.1 μm to 1 μm, more preferably 0.7 μm or less.

Each wiring portion 8 is formed of the same material as the heating element layer 3. Here, the wiring portions 8 and 8 are connected to the both end sides (the first side of the inner side) of the wiring portions 8 and 8 on the first surface 20 side of the substrate 2, respectively, at the opposite ends of the heating element layer 3 (Fig. 1A). The left and right end portions are formed in a form and electrically connected to both end portions of the heating element layer 3, respectively. Further, the wiring portions 8 and 8 are directly connected to the spacers 9 and 9 on the other surface side (the second side of the outer side) of the wiring portions 8 and 8 on the first surface 20 side of the substrate 2, and are electrically connected to each other. For the spacers 9, 9. Here, each of the wiring portions 8 and the spacer 9 are in electrical contact with each other.

The thickness of each of the spacers 9 is preferably in the range of about 0.5 to 2 μm. Each of the gaskets 9 is made of aluminum. The material of each of the spacers 9 is not limited to aluminum, and may be, for example, aluminum alloy (Al-Si) or gold.

In the manufacture of the infrared radiation element 1, for example, on the first surface 20 side of the substrate 2, in order The insulating layer 6, the heating element layer 3, the wiring portions 8, 8 and the protective layer 4 are formed, and then the spacers 9 and 9 are formed. Next, the opening 2a may be formed in the substrate 2.

As a method of forming the tantalum oxide film of the insulating layer 6, for example, a film forming technique such as a thermal oxidation method or a CVD (Chemical Vapor Deposition) method may be employed, and a thermal oxidation method is preferred. Further, the method of forming the tantalum nitride film of the insulating layer 6 may be a thin film forming technique such as a CVD method. However, a LPCVD (Low Pressure Chemical Vapor Deposition) method is preferred.

As a method of forming the heating body layer 3, for example, a thin film forming technique such as a sputtering method, a vapor deposition method, or a CVD method, or a processing technique using a photolithography technique and an etching technique can be employed. Further, when the material and thickness of each wiring portion 8 are set to be the same as the material and thickness of the heating element layer 3, the wiring portions 8 can be formed simultaneously with the heating element layer 3.

As a method of forming the protective layer 4, for example, a thin film forming technique such as a CVD method or a processing technique using a photolithography technique and an etching technique can be employed. The CVD method in forming the protective layer 4 is preferably a plasma CVD method.

Further, for the formation of each of the spacers 9, for example, a thin film formation technique such as a sputtering method, a vapor deposition method, or a CVD method, or a processing technique using a photolithography technique and an etching technique can be employed. Further, in the formation of the opening 2a, a laminated film (not shown) of a tantalum oxide film and a tantalum nitride film on the second surface 21 side of the substrate 2 is used as a mask layer, and the substrate 2 is provided from the second surface 21 side. It can be formed by etching. When the mask layer is formed, for example, first, the tantalum oxide film of the insulating layer 6 is formed, and the tantalum oxide film based on the mask layer is formed on the second surface 21 side of the substrate 2, and the niobium nitride in the insulating layer 6 is formed. At the same time as the film formation, a tantalum nitride film is formed on the second surface 21 side of the substrate 2. The plating of the tantalum oxide film and the tantalum nitride film based on the mask layer may be performed by photolithography and etching.

In the method of manufacturing the infrared radiation element 1 of the present embodiment, when the opening 2a is formed, the insulating layer 6 is used as an etching barrier layer, and the thickness precision of the insulating layer 6 can be improved, and the opening portion 2a side of the insulating layer 6 can be prevented from remaining. There is a portion or residue of the substrate 2. In the manufacturing method, the error in the mechanical strength of the insulating layer 6 of each of the infrared radiation elements 1 and the insulating layer 6 can be suppressed. The heat capacity error of the entire diaphragm portion 6D.

In the manufacture of the infrared radiation element 1, the process until the completion of the formation of the opening 2a is performed at the wafer level, and the opening portion 2a is formed and separated into the respective infrared radiation elements 1. In other words, the infrared radiation element 1 is manufactured, for example, as a base wafer based on the substrate 2, and a plurality of infrared radiation elements 1 are formed by the manufacturing method, and then separated into Each of the infrared radiation elements 1 may be used.

As is apparent from the method of manufacturing the infrared radiation element 1, the infrared radiation element 1 can be manufactured by the manufacturing technique of MEMS.

However, the insulating layer 6 and the protective layer 4 of the infrared radiation element 1 of the present embodiment are made of a material having a linear expansion coefficient closer to that of the heating element layer 3 than the spacer 9. In the infrared radiation element 1 of the present embodiment, the material of the heat generating layer 3 is preferably a material which is chemically stable at a high temperature (for example, 800 ° C or higher) and has a resistivity higher than that of a metal tantalum nitride (TaN). As the material of the protective layer 4, cerium oxide (SiO ₂ ), cerium nitride (SiN) or the like may be used, and SiN, SiO ₂ or the like may be used. TaN, by changing its composition, can change the resistivity and surface resistance. In the infrared radiation element 1 of the present embodiment, the heating element layer 3 has a linear expansion coefficient of 3.6 × 10 ^-6 (K ^-1 ) and a TaN of a specific resistance of 2.4 × 10 ^-4 Ω ‧ m. On the other hand, the material A1 of the spacer 9 has a linear expansion coefficient and a specific resistance of 24 × 10 ^-6 K ^-1 and 2.7 × 10 ^-8 Ω ‧ m, respectively. Further, the linear expansion coefficients of SiO ₂ and SiN were 2.3 × 10 ^-6 K ^-1 and 2.7 × 10 ^-6 K ^{-1 , respectively} . Moreover, the coefficient of linear expansion and resistivity of Ta are 6.3 × 10 ^-6 K ^-1 and 12 × 10 ^-8 Ω ‧ m, respectively. Further, the coefficient of linear expansion of Si is 2.8 × 10 ^-6 K ^-1 . Further, from the viewpoint of improving the reliability of the infrared radiation element 1, the difference between the linear expansion coefficients of the insulating layer 6 and the protective layer 4 and the linear expansion coefficient of the heating element layer 3 is preferably as small as possible.

In the infrared radiation element 1, the gas that contacts the protective layer 4 is air, and the material of the heating element layer 3 is TaN. When the heating element layer 3 is heated at a desired use temperature of, for example, 500 ° C, the heating element layer is used at the use temperature. The maximum surface resistivity of the infrared ray of 3 is 189 Ω/□ (189 Ω/sq.), and the maximum emissivity is 50%. In other words, if the surface resistance of the heating element layer 3 is 189 Ω/□, the infrared radiation element 1 can be made infrared by impedance matching of air. The radioactivity of the line becomes the largest. Therefore, in order to suppress the decrease in emissivity, for example, in order to secure an emissivity of 40% or more, the surface resistance of the heating element layer 3 may be set to a range of 73 to 493 Ω/□. Further, when the surface resistance at which the emissivity at the desired use temperature is the maximum is referred to as a predetermined surface resistance, it is preferable to set the surface resistance of the heating element layer 3 at the use temperature to a range of ±10% of the predetermined surface resistance.

The infrared radiation element 1 includes a substrate 2, a functional layer 5 having a heating element layer 3 and a protective layer 4 covering the heating element layer 3, an insulating layer 6, and a pair of spacers 9, 9 by which the heating element layer 3 is energized. When the heat generation layer 3 generates heat, the heat generating body layer 3 emits infrared rays, and the substrate 2 has an opening 2a in which a part of the surface on the opposite side of the insulating layer 6 is exposed when viewed from the heat generating body layer 3 side. Here, the insulating layer 6 includes a diaphragm portion 6D for isolating the opening portion 2a and the heating element layer 3, and a supporting portion 6S for supporting the diaphragm disposed on the first surface 20 side around the opening portion 2a of the substrate 2. Department 6D. Further, the insulating layer 6 and the protective layer 4 are made of a material having a linear expansion coefficient closer to that of the heat generating body layer 3 than the spacers 9, 9. As described above, the infrared radiation element 1 of the present embodiment can achieve low power consumption and high output, and can improve reliability.

Further, the infrared radiation element 1 has a laminated structure formed on the first surface 20 side of the substrate 2, and is composed of the insulating layer 6, the heating element layer 3, and the protective layer 4, so that the heat capacity of the laminated structure can be reduced. It can achieve low power consumption and high speed of response. In addition, the infrared radiation element 1 can reduce the heat capacity of the laminated structure and can cause the heating element layer 3 to emit infrared rays by energizing the heating element layer 3, so that the output can be increased. Further, in the infrared radiation element 1, since the insulating layer 6 and the protective layer 4 are made of a material having a linear expansion coefficient closer to the heating element layer 3 than the spacers 9, 9, the temperature change of the heating element layer 3 can be reduced to occur in the cascading. The stress of the structure can suppress the damage of the laminated structure and improve the reliability. In addition, the phenomenon of the damage of the laminated structure on the first surface 20 side of the substrate 2 is, for example, a phenomenon in which the heating element layer 3 is peeled off from the diaphragm portion 6D of the insulating layer 6, or a phenomenon in which the laminated structure is cracked.

In the infrared radiation element 1, it is preferable that each spacer 9 is disposed as close as possible to the boundary between the diaphragm portion 6D and the support portion 6S. Specifically, in the plane observation, a part of each outer peripheral line of each spacer 9 and an inner circumference of the inside of the opening 2a when projected in the thickness direction of the insulating layer 6 (substrate) It is preferable that the first surface 20 of the second surface 20 and the boundary line of the inner surface of the opening portion 2a are arranged (over). Thereby, the length of the wiring portion 8 between the spacers 9 and the heating element layer 3 can be shortened in the infrared radiation element 1, and the damage of the laminated structure on the first surface 20 side of the substrate 2 can be further suppressed.

Further, the infrared radiation element 1 of the present embodiment includes a plurality of wiring portions 8 that electrically connect the heating element layer 3 and the plurality of spacers 9, respectively, and each wiring portion 8 is formed of the same material as the heating element layer 3. Thereby, the infrared radiation element 1 can further suppress damage of the laminated structure on the first surface 20 side of the substrate 2.

Further, in the infrared radiation element 1, the substrate 2 is formed of a single crystal germanium substrate, and the insulating layer 6 is composed of a tantalum oxide film and a tantalum nitride film. Therefore, the infrared radiation element 1 has a larger heat capacity and thermal conductivity than the insulating layer 6, and the substrate 2 has the function of a heat sink, so that the size can be reduced and the response speed to the input power can be increased. And the improvement of the stability of infrared radiation characteristics. Further, in the infrared radiation element 1 and the material of the heating element layer 3, if the melting point is higher than the TaN of Si, the temperature of the heating element layer 3 can be raised to the highest use temperature of Si (a temperature slightly lower than the melting point of Si). Compared with the infrared light-emitting diode, the amount of infrared radiation can be greatly increased.

The infrared radiation element 1 has a center line of the infrared radiation element 1 orthogonal to the direction in which the pair of spacers 9 and 9 are arranged in the direction perpendicular to the thickness of the heating element layer 3, and the heating element layer 3 and the wiring portion. 8. The spacers 9 and the spacers 9 are preferably arranged in a line symmetrical manner. Thereby, the infrared radiation element 1 can further improve the mechanical strength and suppress the in-plane error of the temperature of the heating element layer 3.

(Embodiment 2)

Hereinafter, the infrared radiation element 1 of the present embodiment will be described with reference to FIGS. 2A and 2B.

In the infrared radiation element 1 of the present embodiment, each wiring portion 8 is formed of a wiring material having a linear expansion coefficient closer to the heating element layer 3 than the spacer 9, and the infrared ray of the first embodiment The firing element 1 is different. For the wiring material of each wiring portion 8, for example, Ta or Ti or the like can be used. The same components as those in the first embodiment are denoted by the same reference numerals and will not be described.

In the infrared radiation element 1 of the present embodiment, each of the wiring portions 8 is formed of a wiring material having a linear expansion coefficient closer to the heating element layer 3 than the spacer 9, and the infrared radiation element 1 of the first embodiment may have The heating body layer 3 is efficiently heated. As a result, the infrared radiation element 1 of the present embodiment can achieve lower power consumption and higher output than the infrared radiation element 1 of the first embodiment.

In the infrared radiation element 1 shown in FIGS. 2A and 2B, the planar shape of the wiring portion 8 is a shape in which the width of the wiring portion 8 (the size in the upper and lower directions of FIG. 2A) is gradually reduced as it goes away from the spacer 9. . Specifically, the spacers 9 and 9 are each a rectangular shape, and the spacers 9 and 9 are disposed on both sides of the first surface 20 of the substrate 2 in parallel in the longitudinal direction of the spacers 9 and 9. The size of each of the wiring portions 8 in the longitudinal direction of each of the spacers 9 gradually decreases as it goes away from the corresponding spacer 9 (the spacer 9 electrically connected to the wiring portion 8). Moreover, the gasket of the present invention is not limited to the trapezoidal shape. For example, the planar shape of the wiring portion 8 may be a rectangle having a constant width dimension regardless of the distance from the spacer 9 as shown by the infrared radiation element 1 of FIG. In this example, the wiring portion 8 has a rectangular shape having the same width as the spacer 9. In other words, the wiring portions 8 and 8 are disposed inside the spacers 9 and 9 so that the longitudinal directions of the wiring portions 8 and 8 are parallel. Further, the planar shape of the wiring portion 8 may be a rectangular shape having a constant width dimension and the same width dimension as the heat generating body layer 3 regardless of the distance from the spacer 9 as shown in the infrared radiation element 1 of FIG.

(Embodiment 3)

Hereinafter, the infrared radiation element 1 of the present embodiment will be described with reference to FIGS. 5A and 5B.

In the infrared radiation element 1 of the present embodiment, the functional layer 5 has a stress relaxation structure 50, and is different from the infrared radiation element 1 of the second embodiment. The same components as those in the second embodiment are denoted by the same reference numerals and will not be described.

The stress relaxation structure 50 is composed of a plurality of slits 51 penetrating the protective layer 4 and the heating element layer 3. As shown in FIG. 5B, each of the slits 51 is preferably formed so as to penetrate the protective layer 4 and the heat generating layer 3 and penetrate the insulating layer 6.

The number of the slits 51 of the stress relaxation structure 50 is not particularly limited, and may be at least one.

In the infrared radiation element 1, the slits 51 of the plurality (columns) are preferably arranged in a line pair with the center line of the heat generating body layer 3 along the direction in which the pair of spacers 9 and 9 are arranged in parallel. Thereby, the infrared radiation element 1 can not only further improve the mechanical strength, but also can suppress the in-plane error of the temperature of the heating element layer 3.

The slit 51 is preferably an elongated shape in which a direction parallel to the direction in which the pair of spacers 9 and 9 are arranged in the longitudinal direction is formed. Thereby, the infrared radiation element 1 can suppress an increase in the electric resistance of the heating element layer 3 due to the arrangement of the stress relaxation structure 50.

The shape and arrangement of the slits 51 of the stress relaxation structure 50 are not limited to the examples of FIGS. 5A and 5B. For example, as shown in FIG. 6, the slit 51 may have a circular shape, and the slit 51 may be disposed at each lattice point of the virtual triangular lattice.

The stress relaxation structure 50 described in the present embodiment may be disposed in the infrared radiation element 1 of the first embodiment.

(Embodiment 4)

Hereinafter, the infrared radiation element 1 of the present embodiment will be described with reference to Fig. 7 .

In the infrared radiation element 1 of the present embodiment, the functional layer 5 (see FIG. 2B) has a stress relaxation structure 50, and is different from the infrared radiation element 1 of the second embodiment. The same components as those in the second embodiment are denoted by the same reference numerals and will not be described.

The stress relieving structure 50 is constructed by a cut-in groove 52 formed on the outer periphery of the heat generating layer 3 to make. Here, in the infrared radiation element 1, the planar shape of the heating element layer 3 is a right-angled quadrilateral (for example, square or rectangular), and is respectively provided along two outer peripheral edges of the pair of spacers 9, 9 in the direction in which they are disposed, and plural numbers are provided. Cut into the groove 52.

The arrangement of the cut-in grooves 52 of the stress relaxation structure 50 is not limited to the example of FIG. For example, as shown in Fig. 8, the formation position of the cutting groove 52 at the outer peripheral edge of one of the two outer peripheral edges along the adjacent direction and the position of the cutting groove 52 of the other outer peripheral edge may be formed. The parallel directions are staggered from each other. Further, in the infrared radiation element 1 of the example of Fig. 8, the heat generating layer 3 is provided with the stress relieving structure 50, and the planar shape of the heating element layer 3 is a bellows shape.

The stress relaxation structure 50 described in the present embodiment may be disposed in the infrared radiation element 1 of the first embodiment.

Further, the infrared radiation element 1 of each embodiment is not limited to an infrared light source for a gas sensor, and may be used, for example, for an infrared light source for flame detection, an infrared light source for infrared light communication, and an infrared light source for spectroscopic analysis. Wait.

In each of the above embodiments, the central portion side of the opening 2a of the substrate 2 includes only the insulating layer 6, the heating element layer 3, and the protective layer 4. Because of this laminated structure, the heat capacity influence of the laminated structure is smaller than that of the document 1, and it is possible to prevent the temperature change of the voltage waveform supplied to the heat generating body layer 3 by the heat generating body layer 3 from becoming slow.

1‧‧‧Infrared emitting elements

2‧‧‧Substrate

2a‧‧‧ openings

3‧‧‧Fever body layer

4‧‧‧Protective layer

5‧‧‧ functional layer

6‧‧‧Insulation

6a‧‧‧ surface

6D‧‧‧diaphragm department

6S‧‧‧Support Department

8‧‧‧Wiring Department

9‧‧‧shims

20‧‧‧1st

21‧‧‧2nd

Claims (8)

An infrared radiation element comprising: a substrate; a functional layer having a heating element layer formed on one surface side of the substrate; and a protective layer covering the heating element layer; the insulating layer interposed on the surface of the substrate and the functional layer And a pair of spacers formed on the surface of the substrate and electrically connected to the heating element layer; and the heating element layer is radiated by the heating element layer Infrared, characterized in that the substrate includes an opening, and when viewed from the side of the heating element layer, the opening exposes a part of a surface on the opposite side of the insulating layer, and the insulating layer includes a diaphragm portion for isolating the portion The opening portion and the heating element layer; and the supporting portion for supporting the diaphragm portion disposed on the surface side around the opening portion of the substrate; and the insulating layer and the protective layer are provided with the spacer It is composed of a material that is closer to the linear expansion coefficient of the heating body layer. The infrared radiation element according to claim 1, wherein each of the spacers is disposed in the vicinity of a boundary between the diaphragm portion and the support portion. The infrared radiation element according to claim 2, further comprising: a wiring portion for electrically connecting the heating element layer and the spacer, wherein the wiring portion is closer to the heating element layer than the spacer It is composed of a wiring material with a linear expansion coefficient. The infrared radiation element according to claim 2, further comprising a wiring portion for electrically connecting the heating element layer and the spacer, wherein the wiring portion is formed of the same material as the heating element layer. An infrared radiation element as recited in any one of claims 1 to 4, wherein The functional layer has a stress relieving structure. The infrared radiation element according to claim 5, wherein the stress relaxation structure is formed by at least one slit penetrating the protective layer and the heating element layer. The infrared radiation element according to claim 6, wherein the slit has an elongated shape in a longitudinal direction parallel to a direction in which the pair of spacers are disposed in a direction. The infrared radiation element according to claim 5, wherein the stress relaxation structure is formed by a cut-in groove formed on a periphery of the heat generating body layer.