Structure and electromagnetic wave sensor

Abstract

To provide a structure that makes it possible to suppress the heat conduction of an arm unit and heighten the efficiency of absorbing electromagnetic waves in the arm unit.SOLUTION: The present invention comprises an electromagnetic wave detection unit 4, and a pair of arm units 12a, 12b which are located on both sides across the electromagnetic wave detection unit 4. The electromagnetic wave detection unit 4 includes a temperature detection element 5, and electromagnetic wave absorption substances 7a, 7b, 7c that cover at least a portion of the temperature detection element 5. The electromagnetic wave detection unit 4 has a structure of being hung against a substrate 2 that faces the electromagnetic wave detection unit 4 via the pair of arm units 12a, 12b, the area of the side of the arm units 12a, 12b that faces the substrate 2 being larger than the area of the side opposite the side that faces the substrate 2.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a structure and an electromagnetic wave sensor. [Background technology]

[0002] For example, there is an electromagnetic wave sensor that uses an electromagnetic wave detection unit such as a thermistor element. The electrical resistance of the thermistor film of the thermistor element changes in response to changes in the temperature of the thermistor film. In an electromagnetic wave sensor, infrared rays (electromagnetic waves) incident on the thermistor film are absorbed by the thermistor film or the material surrounding the thermistor film, causing a change in the temperature of the thermistor film. This allows the thermistor element to detect the infrared rays (electromagnetic waves).

[0003] According to the Stefan-Boltzmann law, there is a correlation between the temperature of the object being measured and the infrared radiation (radiant heat) emitted from the object by thermal radiation. Therefore, by detecting the infrared radiation emitted from the object using a thermistor element, it is possible to measure the temperature of the object without contact.

[0004] Furthermore, such thermistor elements are arranged in an array and are applied to electromagnetic wave sensors such as infrared imaging elements (infrared image sensors) that detect (image) the temperature distribution of a measurement object in two dimensions (see, for example, Patent Document 1 below). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2019 / 171488 Summary of the Invention [Problem to be solved by the invention]

[0006] In order to perform high-precision sensing in the above-mentioned electromagnetic wave sensor, it is preferable that the thermistor element (electromagnetic wave detection unit) is insulated as much as possible from its surroundings. On the other hand, improving the thermal insulation between the thermistor element and its surroundings can be achieved by making the pair of arms connected to the thermistor element as thin as possible. However, making the arms thin reduces the efficiency of electromagnetic wave absorption in the arms.

[0007] The present invention has been proposed in consideration of the above-described conventional circumstances, and aims to provide a structure that can suppress thermal conduction in the arm portion and increase the efficiency of electromagnetic wave absorption in the arm portion, as well as an electromagnetic wave sensor equipped with such a structure. [Means for solving the problem]

[0008] In order to achieve the above object, the present invention provides the following means. [1] An electromagnetic wave detection unit; a pair of arms positioned on both sides of the electromagnetic wave detection unit, the electromagnetic wave detection unit includes a temperature detection element and an electromagnetic wave absorber that covers at least a portion of the temperature detection element, the electromagnetic wave detection unit has a structure in which it is suspended or hung from a substrate facing the electromagnetic wave detection unit via the pair of arms, A structure characterized in that the area of the surface of the arm portion facing the substrate is larger than the area of the surface of the arm portion opposite to the side facing the substrate. [2] The structure according to [1], wherein the value obtained by dividing the area of the face of the arm portion facing the substrate by the area of the face opposite the face facing the substrate is greater than the value obtained by dividing the area of the face of the electromagnetic wave detection portion facing the substrate by the area of the face opposite the face facing the substrate. [3] The arm portion has a linear shape, The structure described in [1] or [2], characterized in that the width in the short direction of the surface of the arm portion facing the substrate is larger than the width in the short direction of the surface opposite the side facing the substrate. [4] an intermediate layer provided on a surface of the substrate facing the arm portion; an anti-reflection layer provided on a surface of the substrate facing the electromagnetic wave detection unit, The structure described in any one of [1] to [3], characterized in that the reflectance of an electromagnetic wave with a wavelength of 10 μm at a portion of the intermediate layer facing the arm portion is higher than the reflectance of an electromagnetic wave with a wavelength of 10 μm at a portion of the antireflection layer facing the electromagnetic wave detection portion. [5] The structure according to [4], characterized in that a hole penetrating the intermediate layer is provided in a portion of the layer on which the intermediate layer is provided that faces the electromagnetic wave detection unit. [6] An electromagnetic wave sensor comprising the structure according to any one of [1] to [5]. [7] The electromagnetic wave sensor according to [6], wherein a plurality of the structures are arranged in an array. [Effects of the Invention]

[0009] As described above, according to the present invention, it is possible to provide a structure that can suppress thermal conduction in the arm portion and increase the electromagnetic wave absorption efficiency in the arm portion, as well as an electromagnetic wave sensor that includes such a structure. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a plan view showing a configuration of an electromagnetic wave sensor according to an embodiment of the present invention; [Figure 2] FIG. 2 is an exploded perspective view showing the configuration of the electromagnetic wave sensor shown in FIG. [Figure 3] 2 is a plan view showing the configuration of a structure included in the electromagnetic wave sensor shown in FIG. [Figure 4] 4 is a cross-sectional view of the structure taken along line AA shown in FIG. 3. [Figure 5]4 is a cross-sectional view of the structure taken along line BB shown in FIG. 3. [Figure 6] 6 is an enlarged cross-sectional view of an arm portion of the structure shown in FIG. 5. FIG. [Figure 7] 7A to 7C are cross-sectional views illustrating an example of a process for forming the arm portion shown in FIG. 6. [Figure 8] 7A to 7C are cross-sectional views illustrating an example of a process for forming the arm portion shown in FIG. 6. [Figure 9] 7A to 7C are cross-sectional views illustrating an example of a process for forming the arm portion shown in FIG. 6. [Figure 10] 7A to 7C are cross-sectional views illustrating an example of a process for forming the arm portion shown in FIG. 6. [Figure 11] FIG. 10 is a cross-sectional view showing another example of the configuration of the electromagnetic wave sensor. [Figure 12] FIG. 10 is a cross-sectional view showing another example of the configuration of the electromagnetic wave sensor. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings used in the following description, the dimensions of the components may be shown at different scales to make them easier to see, and the dimensional ratios of the components may not necessarily be the same as in reality. Furthermore, the materials exemplified in the following description are merely examples, and the present invention is not necessarily limited to them, and can be implemented with appropriate changes within the scope of the present invention.

[0012] In the drawings shown below, an XYZ Cartesian coordinate system is set, with the X-axis direction representing a first direction X within a specific plane of the electromagnetic wave sensor, the Y-axis direction representing a second direction Y that is perpendicular to the first direction X within the specific plane of the electromagnetic wave sensor, and the Z-axis direction representing a third direction Z that is perpendicular to the specific plane of the electromagnetic wave sensor.

[0013] [Electromagnetic wave sensor] First, an electromagnetic wave sensor 1 shown in, for example, FIGS. 1 to 5 will be described as one embodiment of the present invention.

[0014] FIG. 1 is a plan view showing the configuration of the electromagnetic wave sensor 1. FIG. 2 is an exploded perspective view showing the configuration of the electromagnetic wave sensor 1. FIG. 3 is a plan view showing the configuration of a structure 20 included in the electromagnetic wave sensor 1. FIG. 4 is a cross-sectional view of the structure 20 taken along line AA shown in FIG. 3. FIG. 5 is a cross-sectional view of the structure 20 taken along line BB shown in FIG. 3.

[0015] The electromagnetic wave sensor 1 of this embodiment is an application of the present invention to an infrared imaging element (infrared image sensor) that detects infrared rays (electromagnetic waves) emitted from the object to be measured, thereby detecting (imaging) the temperature distribution of the object to be measured in two dimensions.

[0016] Infrared rays are electromagnetic waves with wavelengths between 0.75 μm and 1000 μm. Infrared image sensors are used as infrared cameras for indoor and outdoor night vision, as well as non-contact temperature sensors for measuring the temperature of people and objects.

[0017] Specifically, as shown in Figures 1 to 5, this electromagnetic wave sensor 1 comprises a first substrate 2 and a second substrate 3 arranged opposite each other, and a plurality of thermistor elements 4 arranged between the first substrate 2 and the second substrate 3.

[0018] The first substrate 2 and the second substrate 3 are made of a silicon substrate that is transparent to electromagnetic waves of a certain wavelength, specifically infrared rays IR including a wavelength band of 10 μm (long wavelength infrared rays with wavelengths of 8 to 14 μm in this embodiment). Also, a germanium substrate or the like can be used as a substrate that is transparent to infrared rays IR.

[0019] The first substrate 2 and the second substrate 3 are sealed around the periphery of their opposing surfaces with a sealant (not shown), thereby forming a sealed internal space K between them. The internal space K is also depressurized to a high vacuum. This suppresses the influence of heat due to convection in the internal space K in the electromagnetic wave sensor 1, and eliminates the influence of heat other than infrared rays IR emitted from the measurement object on the thermistor element 4.

[0020] The electromagnetic wave sensor 1 of this embodiment is not necessarily limited to a configuration in which the sealed internal space K described above is reduced in pressure, but may also be configured to have a sealed or open internal space K at atmospheric pressure.

[0021] The thermistor element 4 includes, as an electromagnetic wave detection section, a thermistor film 5 as a temperature detection element, a pair of first electrodes 6a, 6b provided in contact with one surface of the thermistor film 5, a second electrode 6c provided in contact with the other surface of the thermistor film 5, and insulating films 7a, 7b, 7c as electromagnetic wave absorbers that cover at least a portion (all of the thermistor film 5 in this embodiment), and has a current-perpendicular-to-plane (CPP) structure in which current flows perpendicular to the surface of the thermistor film 5. The insulating film 7b is provided on the side of the pair of first electrodes 6a, 6b opposite to the side in contact with the thermistor film 5.

[0022] That is, in this thermistor element 4, it is possible to pass a current in a direction perpendicular to the surface of the thermistor film 5 from one first electrode 6a to the second electrode 6c, and also to pass a current in a direction perpendicular to the surface of the thermistor film 5 from the second electrode 6c to the other first electrode 6b.

[0023] The thermistor film 5 may be made of, for example, vanadium oxide, amorphous silicon, polycrystalline silicon, oxides with a spinel crystal structure containing manganese, titanium oxide, or yttrium-barium-copper oxide.

[0024] The first electrodes 6a, 6b and the second electrode 6c may be made of a conductive film such as platinum (Pt), gold (Au), palladium (Pd), ruthenium (Ru), silver (Ag), rhodium (Rh), iridium (Ir), or osmium (Os).

[0025] The insulating films 7a, 7b, and 7c may be made of, for example, aluminum nitride, silicon nitride, aluminum oxide, silicon oxide, magnesium oxide, tantalum oxide, niobium oxide, hafnium oxide, zirconium oxide, germanium oxide, yttrium oxide, tungsten oxide, bismuth oxide, calcium oxide, aluminum oxynitride, silicon oxynitride, aluminum magnesium oxide, silicon boride, boron nitride, or sialon (an oxynitride of silicon and aluminum).

[0026] The insulating films 7a, 7b, and 7c may be configured to cover at least a portion of the thermistor film 5. In this embodiment, the insulating films 7a, 7b, and 7c are provided to cover both surfaces of the thermistor film 5.

[0027] The multiple thermistor elements 4 are formed to be the same size as one another. The multiple thermistor elements 4 are arranged in an array in a plane parallel to the first substrate 2 and the second substrate 3 (hereinafter referred to as "in a specific plane"). That is, the multiple thermistor elements 4 are arranged in a matrix in a first direction X and a second direction Y that intersect each other (in this embodiment, they are orthogonal) in the specific plane.

[0028] The thermistor elements 4 are arranged side by side at regular intervals in the first direction X, with the first direction X being the row direction, and the second direction Y being the column direction, and are also arranged side by side at regular intervals in the second direction Y.

[0029] The matrix number of the thermistor element 4 may be, for example, 640 rows x 480 columns, or 1024 rows x 768 columns, but is not necessarily limited to these matrix numbers and can be changed as appropriate.

[0030] On the first substrate 2 side, there are provided a first insulator layer 8 which serves as an intermediate layer, a wiring section 9 which is electrically connected to the circuit section 15 described later, and a first connection section 10 which electrically connects each thermistor element 4 and the wiring section 9.

[0031] The first insulator layer 8 is provided on the surface of the first substrate 2 facing the arm portions 12a and 12b (the surface facing the second substrate 3). A portion of the first insulator layer 8 faces at least a portion of the arm portions 12a and 12b. The first insulator layer 8 is made of a laminated insulating film. Examples of insulating films that can be used include aluminum nitride, silicon nitride, aluminum oxide, silicon oxide, magnesium oxide, tantalum oxide, niobium oxide, hafnium oxide, zirconium oxide, germanium oxide, yttrium oxide, tungsten oxide, bismuth oxide, calcium oxide, aluminum oxynitride, silicon oxynitride, aluminum magnesium oxide, silicon boride, boron nitride, and sialon (an oxynitride of silicon and aluminum).

[0032] The wiring section 9 has a plurality of first lead wires 9a and a plurality of second lead wires 9b. The first lead wires 9a and the second lead wires 9b are made of a conductive film such as copper or gold.

[0033] The first lead wires 9a and the second lead wires 9b are located in different layers of the first insulator layer 8 in the third direction Z and are arranged to intersect three-dimensionally. Of these, the first lead wires 9a extend in the first direction X and are arranged side by side at regular intervals in the second direction Y. On the other hand, the second lead wires 9b extend in the second direction Y and are arranged side by side at regular intervals in the first direction X.

[0034] In plan view, each thermistor element 4 is provided in a region E defined by the plurality of first lead wires 9a and the plurality of second lead wires 9b. In the region where each thermistor film 5 faces the first substrate 2 in the thickness direction (the region where they overlap in plan view), a window W that transmits infrared light IR is present between the first substrate 2 and thermistor film 5.

[0035] 4 and 5, a hole 8a penetrating the first insulator layer 8 is provided in a portion facing the thermistor element 4. In other words, a hole 8a penetrating the first insulator layer 8 is provided between the first substrate 2 and the thermistor element 4. The hole 8a is provided in a portion facing the thermistor element 4 in the layer T on which the first insulator layer 8 is provided.

[0036] The first connection portion 10 has a pair of first connection members 11a, 11b provided corresponding to each of the multiple thermistor elements 4. Furthermore, the pair of first connection members 11a, 11b has a pair of arm portions 12a, 12b and a pair of leg portions 13a, 13b.

[0037] Each of the arm portions 12a, 12b has a wiring layer 21. The wiring layer 21 is formed of a conductive film such as aluminum, tungsten, titanium, tantalum, titanium nitride, tantalum nitride, chromium nitride, or zirconium nitride. In the example shown in FIGS. 3 to 5, the wiring layer 21 is formed in a bent linear shape along the periphery of the thermistor element 4. Each of the leg portions 13a, 13b is made of a conductive pillar with a circular cross section that is formed by plating with, for example, copper, gold, an FeCoNi alloy, or an NiFe alloy (permalloy) and extends in the third direction Z.

[0038] One of the first connection members 11a has a wiring layer 21 included in one of the arm portions 12a electrically connected to one of the first electrodes 6a, and one of the leg portions 13a electrically connecting the wiring layer 21 included in this one of the arm portions 12a and the first lead wiring 9a, thereby electrically connecting the one of the first electrodes 6a and the first lead wiring 9a.

[0039] The other first connection member 11b has a wiring layer 21 included in the other arm portion 12b electrically connected to the other first electrode 6b, and the other leg portion 13b electrically connecting the wiring layer 21 included in this other arm portion 12b and the second lead wiring 9b, and electrically connects the other first electrode 6b and the second lead wiring 9b.

[0040] As a result, the thermistor element 4 is supported in a state in which it is suspended in the third direction Z relative to the first substrate 2 by a pair of first connecting members 11a, 11b located diagonally in the plane of the thermistor element 4. A space G is provided between the thermistor element 4 and the first insulator layer 8.

[0041] Although not shown, one surface of the first substrate 2 (the surface facing the second substrate 3) is provided with a plurality of selection transistors (not shown) for selecting one thermistor element 4 from the plurality of thermistor elements 4. The plurality of selection transistors are provided at positions corresponding to the plurality of thermistor elements 4 on the first substrate 2. Furthermore, each selection transistor is provided at a position that avoids the window portion W described above in order to prevent diffuse reflection of infrared rays IR and a decrease in incidence efficiency.

[0042] On the second substrate 3 side, there are provided a second insulator layer 14, a circuit section 15 that detects changes in the voltage output from the thermistor element 4 and converts it into brightness temperature, and a second connection section 16 that electrically connects each thermistor element 4 and the circuit section 15.

[0043] The second insulator layer 14 is made of an insulating film laminated on one surface (the surface facing the first substrate 2) of the second substrate 3. As the insulating film, the same insulating films as those exemplified for the first insulator layer 8 can be used.

[0044] The circuit section 15 is made up of a read out integrated circuit (ROIC), a regulator, an analog-to-digital converter (A / D converter), a multiplexer, etc., and is provided within the second insulating layer 14.

[0045] Furthermore, a plurality of connection terminals 17a, 17b corresponding to the plurality of first lead wires 9a and the plurality of second lead wires 9b are provided on the surface of the second insulator layer 14. The connection terminals 17a, 17b are made of a conductive film such as copper or gold.

[0046] One of the connection terminals 17a is located in an area on one side of the first direction X that surrounds the periphery of the circuit unit 15, and is arranged side by side at regular intervals in the second direction Y. The other of the connection terminals 17b is located in an area on one side of the second direction Y that surrounds the periphery of the circuit unit 15, and is arranged side by side at regular intervals in the first direction X.

[0047] The second connection portion 16 has a plurality of second connection members 18a, 18b provided corresponding to the plurality of first lead wires 9a and the plurality of second lead wires 9b, respectively. The plurality of second connection members 18a, 18b are made of conductor pillars with a circular cross section formed by plating with, for example, copper or gold, and extending in the third direction Z.

[0048] One second connection member 18a electrically connects one end of the first lead wire 9a to one connection terminal 17a. The other second connection member 18b electrically connects one end of the second lead wire 9b to the other connection terminal 17b. As a result, the multiple first lead wires 9a and the circuit unit 15 are electrically connected via one second connection member 18a and one connection terminal 17a. Also, the multiple second lead wires 9b and the circuit unit 15 are electrically connected via the other second connection member 18b and the other connection terminal 17b.

[0049] An antireflection layer 19 is provided on the surface of the first substrate 2 facing the thermistor element 4. In this embodiment, the antireflection layer 19 is provided between the first substrate 2 and the first insulator layer 8. At least a portion of the antireflection layer 19 faces at least a portion of the thermistor element 4. The antireflection layer 19 prevents the infrared rays IR emitted from the measurement object from being reflected at the interface between the first substrate 2 and the space G before they enter the thermistor film 5 from the first substrate 2 side through the window W, and allows the infrared rays IR that have passed through the first substrate 2 to efficiently enter the thermistor film 5 side.

[0050] The anti-reflection layer 19 may be made of, for example, zinc sulfide, yttrium fluoride, chalcogenide glass, germanium, silicon, zinc selenide, or gallium arsenide.

[0051] Alternatively, the antireflection layer 19 may be configured by alternately laminating films with different refractive indices, and by utilizing the interference of waves reflected by each layer to reduce the reflectance of infrared rays IR. In this case, the antireflection layer 19 may be a laminated film made of, in addition to the above-mentioned materials, an oxide film, a nitride film, a sulfide film, a fluoride film, a boride film, a bromide film, a chloride film, a selenide film, a Ge film, a diamond film, a chalcogenide film, a Si film, or the like.

[0052] In the electromagnetic wave sensor 1 of this embodiment having the above-described configuration, infrared rays IR emitted from the object to be measured enter the thermistor element 4 through the window W from the first substrate 2 side.

[0053] In the thermistor element 4, infrared rays IR incident on the insulating films 7a, 7b, and 7c formed near the thermistor film 5 are absorbed by the insulating films 7a, 7b, and 7c, and infrared rays IR incident on the thermistor film 5 are absorbed by the thermistor film 5, causing a change in the temperature of the thermistor film 5. In the thermistor element 4, the electrical resistance of the thermistor film 5 changes in response to a change in the temperature of the thermistor film 5, causing a change in the output voltage between the pair of first electrodes 6a and 6b. In the electromagnetic wave sensor 1 of this embodiment, the thermistor element 4 functions as a bolometer element.

[0054] In the electromagnetic wave sensor 1 of this embodiment, infrared rays IR emitted from the object to be measured are detected in a planar manner using multiple thermistor elements 4, and then the electrical signal (voltage signal) output from each thermistor element 4 is converted into a brightness temperature, thereby making it possible to detect (image) the temperature distribution (temperature image) of the object to be measured in two dimensions.

[0055] When a constant voltage is applied to the thermistor film 5 of the thermistor element 4, it is also possible to detect a change in the current flowing through the thermistor film 5 in response to a change in the temperature of the thermistor film 5 and convert the change into a luminance temperature.

[0056] [Structure] Next, as one embodiment of the present invention, a structure 20 shown in, for example, FIGS. 3 to 6 will be described. 6 is an enlarged cross-sectional view of the arm portions 12a and 12b of the structure 20. As shown in FIG.

[0057] As shown in Figures 3 to 6, the structure 20 of this embodiment comprises a thermistor element 4 which serves as an electromagnetic wave detection unit, and a pair of arm portions 12a, 12b located on either side of the thermistor element 4, and has a structure in which the thermistor element 4 is suspended from a first substrate 2 facing the thermistor element 4 via the pair of arm portions 12a, 12b.

[0058] The arm portions 12a and 12b are each linear in shape. The arm portions 12a and 12b have a linear wiring layer 21 electrically connected to the thermistor film 5 of the thermistor element 4, and protective layers 22a and 22b, parts of which are disposed on both sides of the wiring layer 21. The protective layers 22a and 22b each have a linear shape that matches the shape of the wiring layer 21. The protective layers 22a and 22b are made of a material with a lower thermal conductivity than the wiring layer 21.

[0059] The protective layers 22a and 22b are made of insulating films 7a, 7b, and 7c that cover the above-mentioned thermistor film 5. Of these, the protective layer (hereinafter referred to as the "first protective layer") 22a arranged on one side of the wiring layer 21 is made of the insulating film 7a, and the protective layer (hereinafter referred to as the "second protective layer") 22b arranged on the other side of the wiring layer 21 is made of the insulating films 7b and 7c. In the following description, as shown in FIG. 6, the above-mentioned insulating films 7a, 7b, and 7c will be omitted from illustration and will be illustrated as protective layers 22a and 22b.

[0060] In a plan view, the pair of arms 12a, 12b are located on either side of the thermistor element 4. In the example shown in Fig. 3, the pair of arms 12a, 12b are arranged point-symmetrically with respect to the center of the thermistor element 4. Each of the arms 12a, 12b has at least a portion that extends along the periphery of the thermistor element 4 and a portion that is connected to the thermistor element 4.

[0061] Specifically, the arm portions 12a, 12b of this embodiment have a structure in which a plurality of (two in this embodiment) portions extending in the first direction X are arranged side by side in the second direction Y, and one end and the other end of adjacent portions are folded back and connected via a portion extending in the second direction Y. The pair of arm portions 12a, 12b are connected to thermistor element 4 at positions sandwiching the thermistor element 4 via the portion extending in the second direction Y.

[0062] In the structure 20 of this embodiment, the area of the faces of the arm portions 12a and 12b facing the first substrate 2 is larger than the area of the faces on the opposite side from the side facing the first substrate 2.

[0063] Specifically, in this structure 20, the width W1 in the short-side direction of the surface of each of the arm portions 12a and 12b facing the first substrate 2 is larger than the width W2 in the short-side direction of the surface opposite the side facing the first substrate 2. Also, in this structure 20, as shown in Fig. 6, the area of a cross section perpendicular to the extension direction of each of the arm portions 12a and 12b is smaller than the product of the thickness t and the width W1 of each of the arm portions 12a and 12b. Furthermore, in this structure 20, as shown in Figs. 4 to 6, the cross section perpendicular to the extension direction of each of the arm portions 12a and 12b has a substantially trapezoidal shape.

[0064] Furthermore, in the structure 20 of this embodiment, the value obtained by dividing the area of the face of the arm portions 12a, 12b facing the first substrate 2 by the area of the face opposite the side facing the first substrate 2 is greater than the value obtained by dividing the area of the face of the thermistor element 4 facing the first substrate 2 by the area of the face opposite the side facing the first substrate 2.

[0065] An example of a process for forming the arm portions 12a and 12b will now be described with reference to Figures 7 to 10. Figures 7 to 10 are cross-sectional views for explaining an example of a process for forming the arm portions 12a and 12b.

[0066] 7, in the process of forming the arm portions 12a and 12b, an aluminum oxide (Al2O3) film 31 that will become the first protective layer 22a, a titanium (Ti) film 32 that will become the wiring layer 21, and an aluminum oxide (Al2O3) film 33 that will become the second protective layer 22b are sequentially laminated on the organic sacrificial layer 30 that will finally be removed by ashing. The thickness of the Al2O3 film 31 is, for example, 2000 Å, the thickness of the Ti film 32 is, for example, 600 Å, and the thickness of the Al2O3 film 33 is, for example, 2000 Å.

[0067] Next, as shown in FIG. 8, a metal film made of nickel chromium (NiCr) is formed on the Al2O3 film 33, and then a mask layer 34 is formed by patterning the mask layer 34 into a shape corresponding to the arm portions 12a and 12b using photolithography technology.

[0068] Next, as shown in FIG. 9, the Al2O3 film 33, the Ti film 32, and the Al2O3 film 31 are patterned into a shape corresponding to the mask layer 34 by reactive ion etching (RIE) using chlorine (Cl) and boron chloride (BCl3) as etching gas.

[0069] At this time, it is possible to control the shape of the arm portions 12a and 12b after etching by controlling the flow rate of the etching gas, RF power, pressure, stage temperature, etc. For example, when the flow rate of Cl is 15 sccm, the flow rate of BCl is 85 sccm, the RF power is 75 W, the pressure is 0.3 Pa, and the stage temperature is 50°C, the etching rate has high anisotropy, and it is possible to etch the Al2O3 film 33, the Ti film 32, and the Al2O3 film 31 perpendicular to the film surfaces.

[0070] In contrast, when the flow rate of Cl is 15 sccm, the flow rate of BCl3 is 85 sccm, the RF power is 50 W, the pressure is 0.3 Pa, and the stage temperature is 50°C, the anisotropy of the etching rate decreases, and it is possible to make the area of the lower Al2O3 film 31 larger than the area of the upper Al2O3 film 33.

[0071] 10, the mask layer 34 is removed by dry milling, thereby forming arm portions 12a and 12b whose area on the first protective layer 22a side is larger than that on the second protective layer 22b side.

[0072] As described above, in the structure 20 of this embodiment, the area of the face of the arm portions 12a, 12b facing the first substrate 2 is larger than the area of the face on the opposite side from the side facing the first substrate 2.

[0073] As a result, in the structure 20 of this embodiment, by keeping the cross-sectional area of the arm portions 12a and 12b small, it is possible to suppress the heat conduction of the arm portions 12a and 12b while increasing the absorption efficiency of electromagnetic waves (infrared rays IR).

[0074] In the structure 20 of this embodiment, electromagnetic waves (infrared rays IR) are absorbed by an electromagnetic wave (infrared rays IR) interference absorption structure formed between the surfaces of the arm portions 12a and 12b facing the first substrate 2 and the first substrate 2 (first insulator layer 8 (intermediate layer) formed on the first substrate 2). The absorption of electromagnetic waves by the interference absorption structure increases as the amount of electromagnetic wave reflection by each interface included in the interference absorption structure increases. In the structure 20 of this embodiment, the amount of electromagnetic wave (infrared rays IR) reflection by the surfaces of the arm portions 12a and 12b facing the first substrate 2 can be increased, so it is possible to increase the efficiency of absorption of electromagnetic waves (infrared rays IR) by this interference absorption structure.

[0075] Furthermore, in the structure 20 of this embodiment, the reflectance of electromagnetic waves with a wavelength of 10 μm at the portion of the first insulator layer 8, which serves as the intermediate layer, facing the arm portions 12 a and 12 b is higher than the reflectance of electromagnetic waves with a wavelength of 10 μm at the portion of the antireflection layer 19 facing the thermistor element 4. Infrared rays IR in this embodiment include electromagnetic waves with a wavelength of 10 μm. The reflectance of the intermediate layer (or antireflection layer) refers to the ratio of the intensity of light reflected from the intermediate layer (or antireflection layer) to the intensity of light incident on the intermediate layer (or antireflection layer). The light reflected from the intermediate layer (or antireflection layer) is a combination of reflected waves from the interfaces of the intermediate layer (or antireflection layer).

[0076] As a result, in the structure 20 of this embodiment, the amount of electromagnetic waves (infrared rays IR) reflected by the portions of the first insulator layer 8 facing the arm portions 12a, 12b can be increased, thereby further increasing the absorption efficiency of electromagnetic waves (infrared rays IR) by the electromagnetic wave (infrared rays IR) interference absorption structure between the portions of the first insulator layer 8 facing the arm portions 12a, 12b and the arm portions 12a, 12b.

[0077] Therefore, in the electromagnetic wave sensor 1 equipped with the structure 20 of this embodiment, by suppressing the thermal conduction of the above-mentioned arm portions 12a, 12b and increasing the absorption efficiency of electromagnetic waves (infrared rays IR), it is possible to perform highly accurate and sensitive sensing using the thermistor element 4.

[0078] The present invention is not necessarily limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. Specifically, in the above embodiment, an example is given of a configuration in which an anti-reflection layer 19 is provided between the first substrate 2 and the first insulator layer 8, but it is also possible to provide an electromagnetic wave sensor 1A in which the anti-reflection layer 19 is provided in a state where it is embedded inside a hole 8a as shown in Fig. 11. Note that in the electromagnetic wave sensor 1A shown in Fig. 11, explanations of parts equivalent to those in the above electromagnetic wave sensor 1 will be omitted and the same reference numerals will be used in the drawing.

[0079] In the electromagnetic wave sensor 1A shown in Figure 11, the antireflection layer 19 is also provided on the side of the first substrate 2 facing the thermistor element 4, and at least a portion of the antireflection layer 19 faces at least a portion of the thermistor element 4.

[0080] Furthermore, in the above embodiment, a suspended electromagnetic wave sensor 1 in which the thermistor element 4 is suspended from the first substrate 2 is exemplified, but it is also possible to use a suspended electromagnetic wave sensor 1B in which the thermistor element 4 is suspended from the second substrate 3, as shown in Fig. 12. In the example shown in Fig. 12, the thermistor element 4, which serves as the electromagnetic wave detection unit, is suspended from the second substrate 3 facing the thermistor element 4. Note that in the electromagnetic wave sensor 1B shown in Fig. 12, explanations of parts equivalent to those in the above electromagnetic wave sensor 1 will be omitted and the same reference numerals will be used in the drawings.

[0081] In this case, for example, the first connection members 11a and 11b are directly connected to a readout circuit (ROIC) provided on the second substrate 3, without using the second connection members 18a and 18b or the wiring portion 9. In the example shown in Fig. 12, a plurality of thermistor elements 4 are arranged in a space sealed by the first substrate 2, the sealing member 23, and the second substrate 3, and an electrode pad 24 electrically connected to the readout circuit (ROIC) is arranged outside the space.

[0082] In the electromagnetic wave sensor 1B, the area of the surfaces of the arm portions 12a and 12b facing the second substrate 3 is larger than the area of the surface opposite the side facing the second substrate 3. Specifically, in the electromagnetic wave sensor 1B, the width in the short-side direction of the surfaces of the arm portions 12a and 12b facing the second substrate 3 is larger than the width in the short-side direction of the surface opposite the side facing the second substrate 3. The area of the cross section perpendicular to the extension direction of the arm portions 12a and 12b is smaller than the product of the thickness of the arm portions 12a and 12b and the width in the short-side direction of the surface facing the second substrate 3. In addition, the value obtained by dividing the area of the surfaces of the arm portions 12a and 12b facing the second substrate 3 by the area of the surface opposite the side facing the second substrate 3 is larger than the value obtained by dividing the area of the surface of the thermistor element 4 facing the second substrate 3 by the area of the surface opposite the side facing the second substrate 3.

[0083] In the structure 20 included in the electromagnetic wave sensor 1B, too, by reducing the cross-sectional areas of the arm portions 12a and 12b, it is possible to suppress heat conduction in the arm portions 12a and 12b while increasing the efficiency of absorbing electromagnetic waves (infrared rays IR). In the structure 20 included in the electromagnetic wave sensor 1B, the electromagnetic waves (infrared rays IR) are absorbed by an interference absorption structure for the electromagnetic waves (infrared rays IR) formed between the surfaces of the arm portions 12a and 12b facing the second substrate 3 and the second substrate 3. In the structure 20 included in the electromagnetic wave sensor 1B, it is possible to increase the amount of reflection of the electromagnetic waves (infrared rays IR) by the surfaces of the arm portions 12a and 12b facing the second substrate 3, and therefore it is possible to increase the efficiency of absorbing electromagnetic waves (infrared rays IR) by this interference absorption structure.

[0084] The electromagnetic wave sensor to which the present invention is applied is not necessarily limited to the configuration of the infrared image sensor in which a plurality of thermistor elements 4 are arranged in an array as described above, and the present invention can also be applied to an electromagnetic wave sensor using a single thermistor element 4 or an electromagnetic wave sensor in which a plurality of thermistor elements 4 are arranged in a line. The thermistor element 4 can also be used as a temperature sensor for measuring temperature.

[0085] Furthermore, the electromagnetic wave sensor to which the present invention is applied is not necessarily limited to one that detects the above-mentioned infrared rays as electromagnetic waves, but may also be one that detects, for example, terahertz waves with a wavelength of 30 μm or more and 3 mm or less.

[0086] Furthermore, the electromagnetic wave sensor to which the present invention is applied is not necessarily limited to one that uses the above-mentioned thermistor element 4 as the electromagnetic wave detection section, and for example, instead of the thermistor film 5, it is possible to use a temperature detection element such as a thermopile (thermocouple), pyroelectric, or diode type as the electromagnetic wave detection section. [Explanation of symbols]

[0087] DESCRIPTION OF SYMBOLS 1, 1A, 1B... Electromagnetic wave sensor 2... First substrate 3... Second substrate 4... Thermistor element (electromagnetic wave detection portion) 5... Thermistor film (temperature detection element) 6a, 6b... First electrode 6c... Second electrode 7a, 7b, 7c... Insulating film (electromagnetic wave absorber) 8... First insulator layer (intermediate layer) 8a... Hole portion 9... Wiring portion 9a... First lead wiring 9b... Second lead wiring 10... First connecting portion 11a, 11b... First connecting member 12a, 12b... Arm portion 13a, 13b... Leg portion 14... Second insulator layer 15... Circuit portion 16... Second connecting portion 17a, 17b... Connection terminal 18a, 18b... Second connecting member 19... Anti-reflection layer 20... Structure 21... Wiring layer 22a...first protective layer 22b...second protective layer

Claims

1. an electromagnetic wave detection unit; a pair of arms positioned on both sides of the electromagnetic wave detection unit, the electromagnetic wave detection unit includes a temperature detection element and an electromagnetic wave absorber that covers at least a portion of the temperature detection element, the electromagnetic wave detection unit has a structure in which it is suspended or hung from a substrate facing the electromagnetic wave detection unit via the pair of arms, a surface of the arm portion facing the substrate faces the substrate across a space; A structure characterized in that the area of the surface of the arm portion facing the substrate is larger than the area of the surface of the arm portion opposite to the side facing the substrate.

2. 2. The structure according to claim 1, wherein the value obtained by dividing the area of the surface of the arm portion facing the substrate by the area of the surface opposite the side facing the substrate is greater than the value obtained by dividing the area of the surface of the electromagnetic wave detection portion facing the substrate by the area of the surface opposite the side facing the substrate.

3. The arm portion has a linear shape, 3. The structure according to claim 1, wherein the width in the short direction of the surface of the arm portion facing the substrate is greater than the width in the short direction of the surface opposite the side facing the substrate.

4. an intermediate layer provided on a surface of the substrate facing the arm portion; an antireflection layer provided on a surface of the substrate facing the electromagnetic wave detection unit, The structure described in any one of claims 1 to 3, characterized in that the reflectivity of electromagnetic waves with a wavelength of 10 μm at a portion of the intermediate layer facing the arm portion is higher than the reflectivity of electromagnetic waves with a wavelength of 10 μm at a portion of the anti-reflection layer facing the electromagnetic wave detection portion.

5. 5. The structure according to claim 4, wherein a hole penetrating the intermediate layer is provided in a portion of the layer on which the intermediate layer is provided, the portion facing the electromagnetic wave detecting portion.

6. An electromagnetic wave sensor comprising the structure according to any one of claims 1 to 5.

7. 7. The electromagnetic wave sensor according to claim 6, wherein a plurality of the structures are arranged in an array.

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