Thin film device

Abstract

To provide a thin film device with excellent durability.SOLUTION: A thin film device 10 has a bridge structure 20 including a stage 21 and one or a plurality of bridges 22 extending from a peripheral edge of the stage 21. An electrode part 26 and a heater part 61 are arranged on the stage 21. The electrode part 26 includes: a first electrode layer 31; a solid electrolyte layer 50 arranged on the first electrode layer 31; and a second electrode layer 41 arranged on the solid electrolyte layer 50. The electrode part 26 and the heater part 61 are not overlapped in a plane view of the bridge structure 20.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to thin film devices. [Background technology]

[0002] Goal 11 of the SDGs aims to make cities and human settlements inclusive, safe, resilient and sustainable, and MEMS devices are expected to contribute to achieving this goal because they consume little power and take up little space. There are many types of MEMS devices known, one of which is a sensor that uses an ion-conducting solid electrolyte. For example, Patent Document 1 describes a solid electrolyte gas sensor having a substrate, a support film, a thin solid electrolyte film formed on the support film, and arms connecting the substrate and the support film, and a heater element is formed on or within the support film.

[0003] Patent Document 2 describes a structure in which a diaphragm portion made of a SiO2 layer or the like is provided on a silicon substrate, the structure being provided with a bridge structure having four bridges formed by removing a part of the diaphragm portion. A pair of electrodes and a heater are formed on the same plane of the stage in the center of the bridge structure. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2001-056313 A [Patent Document 2] JP 2007-132762 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, devices in which the electrodes and heater are arranged on the same surface, as in the techniques described in Patent Documents 1 and 2, have problems with durability. It is therefore an object of the present invention to provide a thin film device having excellent durability. [Means for solving the problem]

[0006] The present invention provides a thin-film device having a bridge structure including a stage and one or more bridges extending from a periphery of the stage, An electrode unit and a heater unit are disposed on the stage, the electrode portion includes a first electrode layer, a solid electrolyte layer disposed on the first electrode layer, and a second electrode layer disposed on the solid electrolyte layer; The above problem is solved by providing a thin film device in which the electrode portion and the heater portion do not overlap when the bridge structure is viewed in a plan view. Effect of the Invention

[0007] According to the present invention, a thin film device with excellent durability is provided. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view that illustrates a preferred embodiment of the thin-film device of the present invention. [Diagram 2] FIG. 2 is a plan view showing the positional relationship between an electrode portion and a heater portion in the thin-film device shown in FIG. [Diagram 3] FIG. 3 is a cross-sectional view of the thin-film device shown in FIG. 1 taken along line III-III. [Figure 4] FIG. 4 is a cross-sectional view of the thin-film device shown in FIG. 1 taken along line IV-IV. [Diagram 5] 5(a) to 5(c) are plan views showing other embodiments of the thin film device of the present invention, and correspond to FIG. [Figure 6]6(a) to 6(h) are perspective views each showing a schematic diagram of a preferred method for producing the thin-film device shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described based on preferred embodiments with reference to the drawings. The thin film device of the present embodiment is preferably used as a gas sensor, and more preferably used as an oxygen gas sensor.

[0010] 1 to 4 show a preferred embodiment of the thin film device of the present invention. The thin film device 10 of this embodiment has a bridge structure 20 including a stage 21 and one or more bridges 22 extending from the periphery of the stage 21. In the thin film device 10 shown in FIG. 1, the bridge structure 20 has the stage 21 made of a rectangular plate-like body in a plan view, and four bridges 22 extending from the periphery of the stage 21. The bridges 22 extend from the four corners of the stage 21. The thin film device 10 also has a periphery 24 that is connected to the bridges 22 and surrounds the stage 21. The shape of the stage 21 in a plan view is not limited to a rectangle. 2, when the stage 21 has a polygonal shape and the bridge 22 extends from the vertices of the polygon, the boundary between the stage 21 and the bridge 22 is not necessarily clear. In this case, for convenience, each side of the stage 21 is extended until it intersects with an adjacent side or its extension. Then, the region of the bridge structure 20 surrounded by each side extended in this way is defined as the stage 21, and the portion outside this region is defined as the bridge 22. 3 and 4, in the thin-film device 10, an electrode unit 26 and a heater unit 61 are disposed on a stage 21. The electrode unit 26 includes a first electrode layer 31, a solid electrolyte layer 50 disposed on the first electrode layer 31, and a second electrode layer 41 disposed on the solid electrolyte layer 50. The first electrode layer 31 and the solid electrolyte layer 50 are generally in direct contact over the entire area of ​​their opposing surfaces, but may be in direct contact with each other partially or may have some layer interposed therebetween as long as the object of the present invention is achieved. Similarly, the second electrode layer 41 and the solid electrolyte layer 50 are generally in direct contact with each other over the entire area of ​​their opposing surfaces, but may be in direct contact with each other partially or may have some layer interposed therebetween as long as the object of the present invention is achieved.

[0011] 2, in the thin-film device 10, the electrode portion 26 and the heater portion 61 do not overlap in a plan view of the bridge structure 20. Since the electrode portion 26 and the heater portion 61 are arranged in such a positional relationship, no steps due to the thickness of the heater portion 61 are generated in the first electrode layer 31, the solid electrolyte layer 50, and the second electrode layer 41. As a result, cracks originating from the steps are less likely to occur in the first electrode layer 31, the solid electrolyte layer 50, and the second electrode layer 41, and the durability of the thin-film device 10 is improved.

[0012] 3 and 4, in the thin-film device 10, the stage 21 has a three-layer structure. In detail, the stage 21 has a first insulating layer 121, a second insulating layer 122 disposed on the first insulating layer 121, and a third insulating layer 123 disposed on the second insulating layer 122. However, the stage 21 may have a single-layer structure, or a multi-layer structure other than the three-layer structure, such as a two-layer structure or a four-layer structure. In addition, in the thin-film device 10, a fourth insulating layer 124 is disposed on the stage 21 (on the third insulating layer 123). In the thin-film device 10 shown in FIG. 2, the fourth insulating layer 124 is omitted in order to clearly show the positional relationship between the electrode portion 26 and the heater portion 61.

[0013] The heater portion 61 is disposed on the third insulating layer 123 . The heater section 61 is capable of generating heat. By generating heat from the heater section 61, the electrode section 26 can be heated, and thus the ionic conductivity and electronic conductivity of the solid electrolyte layer 50 can be further increased.

[0014] The heater section 61 is preferably made of a single wire, as shown in Fig. 2. In this case, the "heater section 61" refers to the portion of the wire that is disposed on the stage 21. The wire that is disposed on the stage 21 extends to the two bridges 22, 22 and the peripheral portion 24, forming two heater wires 62, 62. In order to enable the two heater wires 62, 62 to be formed on the bridge 22, it is preferable that at least two bridges extend from the peripheral portion of the stage 21. The heater section 61 is connected to two wire bonding pads 63, 63 arranged on the peripheral portion 24 via two heater wires 62, 62. Hereinafter, the wire bonding pad 63 is also referred to as the "heater pad 63".

[0015] From the viewpoint of reducing power consumption, the electric resistance R of the wire (heater part 61) arranged on the stage 21 is S The electric resistance R of the wire (heater wiring 62) extending to the bridge and the peripheral portion B In particular, R S and R B Ratio to S / R B is preferably 1 or more, more preferably 2 or more, and even more preferably 4 or more. S and R B Ratio to S / R B The higher the better, but a value of 50 or less is realistic. R S R B2, an example of a means for relatively increasing the resistance of the heater section 61 is to use a single filament that extends while meandering in one direction and the opposite direction to the one direction, and to make the filament thinner in the heater section 61 than in the heater wiring 62. Also, the heater section 61 and the heater wiring 62 may be made of materials having different resistances. In this case, the resistance of the heater section 61 is made higher than the resistance of the heater wiring 62. Also, R S / R B From the viewpoint of sufficiently increasing the linearity, it is more preferable that the filaments do not cross.

[0016] The thickness of the heater portion 61 is preferably 20 nm or more and 2000 nm or less, more preferably 30 nm or more and 1500 nm or less, and further preferably 50 nm or more and 1000 nm or less. By setting the thickness of the heater section 61 to 20 nm or more, the resistance of the heater section 61 can be increased, and the heater section 61 can generate sufficient heat in a relatively low applied voltage range. As a result, power consumption can be reduced. In addition, the durability of the heater section 61 can be sufficiently increased, and thus breakage of the heater section 61 can be prevented. Moreover, by setting the thickness of the heater portion 61 to 2000 nm or less, the manufacturing cost can be reduced.

[0017] From the viewpoint of appropriately adjusting the resistance of the heater portion 61, the minimum cross-sectional area of ​​the heater portion 61 is preferably 0.5 μm 2 More than 200μm 2 More preferably, it is 1.5 μm or less. 2 More than 150μm 2 More preferably, it is 2 μm or less. 2 More than 100μm 2 The minimum cross-sectional area is the smallest of the areas of the cross section of the heater portion 61 perpendicular to the direction in which the current flows.

[0018] It is preferable that a fourth insulating layer 124 is disposed on the side and above the heater section 61. This makes it possible to prevent the heater section 61 from reacting with components contained in the surrounding gas, thereby extending the life of the heater section 61. In addition, from the viewpoint of increasing the adhesion between the heater portion 61 and the third insulating layer 123 and the fourth insulating layer 124, it is preferable that a first adhesion layer 64 and a second adhesion layer 65 are arranged in positions contacting the upper and lower surfaces of the heater portion 61, respectively. When the first adhesion layer 64 and the second adhesion layer 65 are arranged in a position contacting the upper and lower surfaces of the heater section 61, it is preferable that the first adhesion layer 64 and the second adhesion layer 65 are also arranged in a position contacting the upper and lower surfaces of the heater wiring 62 and the heater pad 63.

[0019] In order to sufficiently increase the adhesion between the heater portion 61 and the third insulating layer 123 and the fourth insulating layer 124, the thicknesses of the first adhesion layer 64 and the second adhesion layer 65 are each independently preferably 1 nm or more and 200 nm or less, more preferably 2 nm or more and 150 nm or less, and even more preferably 10 nm or more and 100 nm or less.

[0020] 1 and 3, a part of the fourth insulating layer 124 disposed on the heater pad 63 is removed. As a result, a part of the second adhesive layer 65 (in an embodiment in which the second adhesive layer is not present) is exposed to the outside.

[0021] An electrode unit 26 including a first electrode layer 31, a solid electrolyte layer 50, and a second electrode layer 41 laminated in this order is disposed on the fourth insulating layer 124 formed on the stage 21. As shown in FIG. 2, in this embodiment, the electrode unit 26 is disposed in the center of the stage 21.

[0022] The first electrode layer 31 is located above the fourth insulating layer 124 and is in contact with the fourth insulating layer 124 and the solid electrolyte layer 50 . The thickness of the first electrode layer 31 is preferably 10 nm or more and 2000 nm or less, more preferably 20 nm or more and 1600 nm or less, and even more preferably 30 nm or more and 1200 nm or less, from the viewpoint of increasing the amount of gas diffusing in the first electrode layer and improving the S / N ratio when the thin-film device 10 is used as a gas sensor.

[0023] The second electrode layer 41 is located above the solid electrolyte layer 50 and is in contact with the solid electrolyte layer 50. The upper surface of the second electrode layer 41 is exposed to the outside. From the viewpoint of sufficiently increasing the release rate of the gas generated in the second electrode layer, the thickness of the second electrode layer 41 is preferably 10 nm or more and 1000 nm or less, and more preferably 20 nm or more and 700 nm or less.

[0024] The solid electrolyte layer 50 is located between the first electrode layer 31 and the second electrode layer 41, and is in contact with the first electrode layer 31 and the second electrode layer 41. The solid electrolyte layer 50 preferably has ion conductivity. When the thin-film device 10 is used as a gas sensor for oxygen gas or the like, the solid electrolyte layer 50 preferably has oxide ion conductivity. The thickness of the portions of solid electrolyte layer 50 that overlap first electrode layer 31 and second electrode layer 41 in a plan view is not particularly limited, but is, for example, not less than 10 nm and not more than 1000 nm.

[0025] The thickness of each of the above-mentioned layers can be measured by a stylus step gauge, an electron microscope, or an optical three-dimensional measuring device.

[0026] The electrode portion 26 preferably has a shape of, for example, a circle, an ellipse, or a polygon in plan view. This can alleviate stress concentration in the laminated structure of the first electrode layer 31 and the solid electrolyte layer 50, thereby obtaining a thin film device 10 with few defects. Examples of the polygonal shape include a square, a pentagon, and a polygon having more than one side. When the electrode portion 26 has a polygonal shape, it is desirable to provide a curvature portion in the shape of an outwardly convex arc at the corner, from the viewpoint of making the above-mentioned advantages more prominent. However, the shape of the electrode portion 26 in plan view is not limited to a circle, an ellipse, and a polygon, and may be any shape, such as a petal shape, a star shape, an indefinite shape, or a combination thereof.

[0027] As described above, in the thin-film device 10, the electrode portion 26 and the heater portion 61 do not overlap in a plan view of the bridge structure 20, so that cracks are less likely to occur in the first electrode layer 31, the solid electrolyte layer 50, and the second electrode layer 41. From the viewpoint of making this effect even more prominent, the distance between the electrode portion 26 and the heater portion 61 in a plan view is preferably 0.10 μm or more, more preferably 0.5 μm or more, and even more preferably 1 μm or more.

[0028] As shown in FIG. 2, in the plan view of the bridge structure 20, the electrode portion 26 of the thin film device 10 has the heater portion 61 disposed adjacent to the electrode portion 26. By having such a positional relationship between the electrode portion 26 and the heater portion 61, the electrode portion 26 can be brought closer to the heater portion 61, so that the solid electrolyte layer 50 in the electrode portion 26 can be heated more efficiently. From the viewpoint of making such an effect more prominent, the distance between the electrode portion 26 and the heater portion 61 in the plan view is preferably 500 μm or less, more preferably 300 μm or less, and even more preferably 200 μm or less. The distance refers to the distance between the periphery of the electrode portion 26 and the periphery of the heater portion 61. When the distance is not constant, the shortest distance is taken as the distance between the electrode portion 26 and the heater portion 61.

[0029] When the electrode part 26 has an n-sided shape (n is an integer of 3 or more), it is preferable that the heater part 61 is adjacent to n-1 or less sides other than at least one side of the electrode part 26, from the viewpoint of heating the solid electrolyte layer 50 more efficiently by bringing the electrode part 26 closer to the heater part 61. Here, "n-1 or less sides of the electrode part 26 are adjacent to the heater part 61" means that the electrode part 26 has n-1 or less sides whose distance from the periphery of the heater part 61 in a plan view is preferably 500 μm or less, more preferably 300 μm or less, and even more preferably 200 μm or less. The distance refers to the distance between the side of the electrode part 26 and the periphery of the heater part 61. When the distance is not constant, the shortest distance is taken as the distance between the electrode part 26 and the heater part 61. In order to minimize temperature unevenness in the electrode portion 26 that occurs when the electrode portion 26 is heated and to prevent damage to the electrode portion 26 due to the temperature unevenness, it is more preferable that the n-1 sides of the electrode portion 26 are adjacent to the heater portion 61. Furthermore, it is also preferable that the first wiring 32 extends outward from the remaining side of the electrode portion 26. As shown in FIG. 2, in the thin-film device 10, the electrode portion 26 has a rectangular shape, and the three sides except one side are adjacent to the heater portion 61.

[0030] From the viewpoint of suppressing temperature unevenness of the electrode portion 26 that occurs when the electrode portion 26 is heated, it is preferable that the distance between the centroid of the electrode portion 26 and the centroid of the heater portion 61 in a plan view is sufficiently small. In particular, the distance between the centroid of the electrode portion 26 and the centroid of the heater portion 61 in a plan view is preferably 300 μm or less, more preferably 275 μm or less, and even more preferably 250 μm or less. Moreover, the smaller the distance between the centroid of the electrode portion 26 and the centroid of the heater portion 61 in a plan view, the more preferable it is, and ideally it is 0 μm.

[0031] The distance in the thickness direction between the electrode part 26 and the heater part 61, i.e., the distance between the plane including the lower surface of the first electrode layer 31 and the plane including the upper surface of the heater part 61, is preferably 0.01 μm to 10 μm, more preferably 0.02 μm to 7 μm, and even more preferably 0.03 μm to 5 μm. By setting the distance in the thickness direction between the electrode part 26 and the heater part 61 within this range, it is possible to prevent dielectric breakdown between the heater part 61 and the electrode part 26. In addition, the resistance of the heater part 61 becomes high and the fourth insulating layer 124 on the stage 21 has a low heat capacity, which results in a reduction in the power consumption of the thin film device 10.

[0032] Figures 5(a) to (c) show another preferred embodiment of the thin-film device of the present invention. The electrode portion 26 of the thin-film device 10 shown in Figure 5(a) is arranged not in the center of the stage 21 but offset toward the side area of ​​the stage 21. The heater portion 61 of the thin-film device 10 shown in Figures 5(b) and (c) has a finer, meandering wire compared to the heater portion 61 of the thin-film device 10 shown in Figures 2 and 5(b). As a result, the thin-film device 10 shown in Figures 5(b) and (c) has a smaller resistance R of the heater portion 61 compared to the thin-film device 10 shown in Figure 2. S is higher.

[0033] As described above, the thin-film device 10 has a peripheral portion 24 that surrounds the stage 21. The peripheral portion is preferably spaced apart from the stage 21, and the two are preferably connected via a bridge 22. The peripheral portion 24 preferably includes a substrate 11 and a plurality of insulating layers formed above and below the substrate 11. In particular, as shown in Figures 3 and 4, a first insulating layer 121, a second insulating layer 122, a third insulating layer 123, and a fourth insulating layer 124 are disposed in this order above the substrate 11. Also, a fifth insulating layer 125 and a sixth insulating layer 126 are disposed in this order below the substrate 11.

[0034] The thin-film device 10 may or may not have the fifth insulating layer 125 and the sixth insulating layer 126. Depending on the presence or absence of the fifth insulating layer 125 and the sixth insulating layer 126, the stress applied to the substrate 11 can be adjusted.

[0035] The thin-film device 10 preferably has a first wiring 32 extending from the periphery of the first electrode layer 31. The first electrode layer 31 is preferably connected to a wire bonding pad 33 (hereinafter also referred to as a "first electrode layer pad 33") via the first wiring 32. An end region of the first wiring 32 on the first electrode layer 31 side is covered with a solid electrolyte layer 50. Similarly, the thin-film device 10 preferably has a second wiring 42 extending from the periphery of the second electrode layer 41. In addition, the second electrode layer 41 is preferably connected to a wire bonding pad 43 (hereinafter also referred to as a "second electrode layer pad 43") via the second wiring 42. The first wiring 32 and the second wiring 42 are disposed on the stage 21 and the bridge 22, respectively. Hereinafter, a structure consisting of the first electrode layer 31 and the first wiring 32 extending from the periphery of the first electrode layer 31 will also be referred to as a "first electrode structure 30." Similarly, a structure consisting of the second electrode layer 41 and the second wiring 42 extending from the periphery of the second electrode layer 41 will also be referred to as a "second electrode structure 40."

[0036] When the first electrode layer 31 and the first wiring 32 constituting the first electrode structure 30 are made of the same material, the boundary between them is not necessarily clear. Thus, in this specification, when the first electrode layer 31 has a circular, elliptical or polygonal shape in a planar view, the portion having this shape is referred to as the first electrode layer 31. When the first electrode layer 31 does not have a circular, elliptical or polygonal shape in a planar view, the portion of the first electrode structure 30 that overlaps with the second electrode structure 40 in a planar view is referred to as the first electrode layer 31. Similarly, in this specification, when the second electrode layer 41 has a circular, elliptical, or polygonal shape in a planar view, the portion having that shape is referred to as the second electrode layer 41. When the second electrode layer 41 does not have a circular, elliptical, or polygonal shape in a planar view, the portion of the second electrode structure 40 that overlaps with the first electrode structure 30 in a planar view is referred to as the second electrode layer 41.

[0037] From the viewpoint of reducing manufacturing costs, the first electrode layer 31, the first wiring 32, and the first electrode layer pad 33 are preferably made of the same material. From a similar viewpoint, the second electrode layer 41, the second wiring 42, and the second electrode layer pad 43 are preferably made of the same material.

[0038] The thin film device of the present invention can be used as a gas sensor by using either the first electrode layer or the second electrode layer as a cathode and the other as an anode. In particular, the thin film device of the present invention can be suitably used as a limiting current type gas sensor. For example, when the thin film device 10 of the embodiment shown in FIGS. 1 to 4 is used as an oxygen gas sensor, it is preferable to use the first electrode layer 31 as a cathode and the second electrode layer 41 as an anode.

[0039] When the thin film device 10 is used as a gas sensor, it is necessary to allow the gas to be detected to reach the first electrode layer. For this purpose, it is preferable that the first electrode structure 30 of the thin film device 10 includes a porous body in at least a part thereof. This allows voids to be provided inside the first electrode structure 30, so that the gas to be detected can diffuse inside the first electrode structure 30. Due to this, the gas taken in from the first wiring 32 can reach the first electrode layer 31 through the first wiring 32. In addition, by changing the material and configuration of the porous body, the diffusion speed of the gas inside the one electrode structure can be adjusted, so that the inflow speed of the gas into the first electrode layer 31 can be easily adjusted. This is particularly advantageous when the thin film device 10 is used as a limiting current type gas sensor. In order to ensure that the above-mentioned effects are achieved, it is preferable that the first electrode structure 30 entirely includes a porous body. Furthermore, it is preferable that the porous body has an open cell structure.

[0040] From the viewpoint of appropriately adjusting the inflow rate of gas into the first electrode layer 31, the first electrode structure 30 preferably contains a metal oxide and has a porosity ρ0 of 1.0% to 50%, more preferably 5.0% to 45%, and even more preferably 15.0% to 40%. Details of the metal oxide will be described later.

[0041] In order to set the porosity ρ0 of the first electrode structure 30 within the above-mentioned range, the proportion of metal oxide in the first electrode structure 30 is preferably 1.0 vol.% or more and 60 vol.% or less, and more preferably 2.0 vol.% or more and 55 vol.% or less.

[0042] The first wiring 32 of the thin film device 10 preferably has a diffusion rate-limiting layer P in a portion of the first wiring 32 that is disposed on the stage 21. As shown in FIGS. 1 and 4, in the thin film device 10, the end region of the first wiring 32 on the first electrode layer 31 side is covered with a solid electrolyte layer 50 to form a diffusion rate-limiting layer P. The diffusion rate-limiting layer P is covered with the solid electrolyte layer 50 and is not exposed to the outside air. Due to this, in order for the gas to be detected to reach the first electrode layer 31, the gas needs to pass through the diffusion rate-limiting layer P after being taken into the first wiring 32. Therefore, the inflow rate of the gas to be detected into the first electrode layer 31 can be easily adjusted by the diffusion rate-limiting layer P.

[0043] In detail, when the diffusion-controlling layer P is cut perpendicularly to the gas diffusion direction to obtain a cross section of the one electrode structure, the minimum cross-sectional area at the portion where the area of ​​the cross section is the smallest is defined as Sr, and the area of ​​the region where the first electrode layer 31 and the second electrode layer 41 overlap in a plan view is defined as Sp, Sr / Sp is 1.0×10 -7 More than 6.9 x 10 -4It is preferable that Sr / Sp is 1.0×10 -7 By setting the ratio of Sr to Sp at or above the above range, the gas can be supplied to the first electrode layer 31 at a rate sufficient for the reaction rate in the electrode portion 26, thereby improving the S / N ratio of the gas sensor. -4 By setting the voltage at or below this value, a limiting current is generated without applying an excessive voltage, so that power consumption can be reduced and deterioration of first electrode layer 31, second electrode layer 41, and solid electrolyte layer 50 can be suppressed. To make this advantage even more pronounced, the Sr / Sp ratio is 1.0×10 -6 Above 6.0×10 -4 It is more preferable that:

[0044] It is preferable that the cross-sectional shape of the diffusion-controlling layer P along the thickness direction at the location where the minimum cross-sectional area Sr is located is a trapezoid or a rectangle from the viewpoint of facilitating the manufacture of the first electrode structure 30. The cross-sectional shape of the diffusion-controlling layer P along the thickness direction at the location where the minimum cross-sectional area Sr is located is measured by an electron microscope, and Sr can be obtained by a known method based on the results. For example, when the cross-sectional shape is a trapezoid, Sr can be calculated by dividing it into four triangles and calculating the sum of their areas. When the cross-sectional shape is a rectangle, Sr can be calculated by subtracting the excess areas of two places that can be approximated by triangles from the surrounding rectangular area.

[0045] When the gas reaches the first electrode layer 31, a reaction according to the type of the gas proceeds on the first electrode layer 31 side and the second electrode layer 41 side. For example, when the thin-film device 10 is used as a limiting current type oxygen gas sensor, the following reaction proceeds. First electrode layer 31 (cathode) side: O2+4e - →2O 2- Second electrode layer 41 (anode) side: 2O 2- →O2+4e -

[0046] In the thin film device 10, the heater section 61 is arranged so that the heating temperature of the first electrode layer 31 is higher than the heating temperature of the diffusion-controlling layer P. This allows the temperature of the diffusion-controlling layer P to be kept low when the electrode section 26 of the thin film device 10 is heated to a predetermined temperature according to the application. As a result, the deterioration of the diffusion-controlling layer P caused by heat can be suppressed, and the durability of the thin film device 10 can be further improved. From the viewpoint of obtaining such an effect more reliably, when the first electrode layer 31 is heated to 600°C, the temperature of the diffusion-controlling layer P is preferably 590°C or less, more preferably 580°C or less, and even more preferably 570°C or less. When the temperature of the first electrode layer 31 varies depending on the position, the temperature is the temperature at the hottest position. Similarly, when the temperature of the diffusion-controlling layer P varies depending on the position, the temperature is the temperature at the hottest position. In order to make the heating temperature of the first electrode layer 31 higher than the heating temperature of the diffusion-controlling layer P, the heater section 61 may be disposed closer to the electrode section 26 than the diffusion-controlling layer P. More specifically, as shown in FIG. 2 and FIG. 5(a) to (c), the heater section 61 may be disposed so as to surround the periphery of the electrode section 26 in a plan view, or the heater section 61 may be disposed so as not to overlap the diffusion-controlling layer P (first wiring 32) in a plan view. The heater section 61 may also be disposed so that the diffusion-controlling layer P is not adjacent to the heater section 61. Furthermore, by increasing the width of the bridge 22 located under the first wiring 32 or shortening the path length of the portion of the first wiring 32 located between the diffusion-controlling layer P and the peripheral portion 24, the heat conduction is improved, and therefore the heating temperature of the diffusion-controlling layer P can be reduced.

[0047] From the above viewpoints, the width of the bridge 22 located below the first wiring 32 is preferably 1 μm or more, more preferably 10 μm or more, and even more preferably 20 μm or more. From the viewpoint of reducing power consumption, the width of the bridge 22 located below the first wiring 32 is preferably 300 μm or less, more preferably 200 μm or less, and even more preferably 100 μm or less.

[0048] From the above viewpoints, the path length of the portion of the first wiring 32 located between the diffusion rate-controlling layer P and the peripheral portion 24 is preferably 3000 μm or less, more preferably 2000 μm or less, and even more preferably 1000 μm or less. From the viewpoint of reducing power consumption, the path length is preferably 10 μm or more, more preferably 50 μm or more, and even more preferably 100 μm or more.

[0049] Next, the materials of each layer described above will be described. The substrate 11 preferably comprises silicon (Si). The insulating layers formed on the upper and lower surfaces of the substrate 11 preferably contain a silicon (Si) compound from the viewpoints of availability, ease of formation, and chemical stability. Examples of suitable insulating layers include silicon dioxide (SiO2) and silicon nitride (SiN x , x is a number between 0.100 and 1.667.) More specifically, the first insulating layer 121, the third insulating layer 123, the fourth insulating layer 124, and the fifth insulating layer 125 are made of SiO2, and the second insulating layer 122 and the sixth insulating layer 126 are made of SiN x It is preferable that the composition comprises:

[0050] The heater portion 61 includes a material capable of generating heat, such as metals and metal compounds, and more specifically, platinum, platinum alloys, tungsten and molybdenum, nickel alloys, titanium nitride, titanium, polycrystalline silicon, indium tin oxide, etc., but is not limited to these. In order to enhance adhesion to the third insulating layer 123 and the fourth insulating layer 124, the first adhesion layer 64 and the second adhesion layer 65 preferably contain one or more selected from tantalum (Ta), titanium (Ti), titanium nitride, titanium oxide, titanium oxynitride, tantalum oxide, zirconium, zirconium oxide, yttrium, yttrium oxide, tungsten, tungsten oxide, chromium, chromium oxide, nickel, nickel oxide, and alloys thereof.

[0051] The materials of the heater wiring 62 and the heater pad 63 can be the same as those mentioned above for the heater section 61, and can be used independently. The heater section 61, the heater wiring 62, and the heater pad 63 may be made of different materials or the same material. From the viewpoint of enabling simple manufacturing and reducing manufacturing costs, it is preferable that the heater section 61, the heater wiring 62, and the heater pad 63 are made of the same material.

[0052] The first electrode layer 31 preferably contains at least one precious metal element selected from the group consisting of platinum group elements (platinum (Pt), palladium (Pd), rhodium (Rh), ruthenium (Ru), iridium (Ir), and osmium (Os)), gold (Au), and alloys containing these. The first electrode layer 31 also preferably contains an ion-conductive metal oxide (hereinafter, also simply referred to as a "metal oxide"). In particular, the first electrode layer 31 is preferably a porous composite of a metal oxide and the metal element, particularly a cermet. This improves the heat resistance of the first electrode layer 31 and makes it less likely to become densified when heated, making it easier to maintain the voids formed in the first electrode layer 31. The alloy may be a general-purpose alloy such as a Pt-Rh alloy, an Au-Pt alloy, an Au-Pd alloy, etc. The metal oxide may be any of the metal oxides contained in the solid electrolyte layer 50, which will be described later.

[0053] The materials of the first wiring 32 and the first electrode layer pad 33 can be the same as those of the first electrode layer 31, and can be used independently of each other. The first electrode layer 31, the first wiring 32, and the first electrode layer pad 33 may be made of different materials or the same material. From the viewpoint of enabling simple manufacturing and reducing manufacturing costs, the first electrode layer 31, the first wiring 32, and the first electrode layer pad 33 are preferably made of the same material.

[0054] The second electrode layer 41 may be made of a general-purpose electrode material, such as a metal electrode or graphite, or, like the first electrode layer 31, may be a porous composite of a metal oxide and a metal, in particular a cermet. The materials of the second wiring 42 and the pads for the second electrode layer 43 can be the same as those described above for the material of the second electrode layer 41, and can be used independently of each other. The second electrode layer 41, the second wiring 42, and the pads for the second electrode layer 43 may be made of different materials or the same material. From the viewpoint of enabling simple manufacturing and reducing manufacturing costs, it is preferable that the second electrode layer 41, the second wiring 42, and the pads for the second electrode layer 43 are made of the same material.

[0055] The solid electrolyte layer 50 is 1 , M 2 and O. By using such a compound, it is possible to further increase the oxide ion conductivity of the solid electrolyte. 1 is one or more elements selected from the group consisting of La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, Lu, Be, Mg, Ca, Sr, Y, Ba and Bi. 2 is one or more elements selected from the group consisting of Mg, Al, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Ga, Zr, Ta, Nb, B, Si, Ge, Zn, Sn, W, and Mo. The compound preferably has an apatite-type crystal structure.

[0056] In particular, the solid electrolyte is represented by the formula (1)M 1 9.33+x [T 6.00-y M 2 y ]O 26.0+z In order to further increase the oxide ion conductivity of the solid electrolyte, it is preferable to contain a composite oxide represented by the formula: 1As described above, is one or more elements selected from the group consisting of La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, Lu, Be, Mg, Ca, Sr, Y, Ba and Bi. T is an element containing Si or Ge or both. M 2 is one or more elements selected from the group consisting of Mg, Al, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Ga, Zr, Ta, Nb, B, Zn, Sn, W, and Mo. x is a number between -1.33 and 1.50. y is a number between 0.00 and 3.00. z is a number between -5.00 and 5.20. The ratio of M to the number of moles of T 1 The molar ratio of these is equal to or greater than 1.33 and equal to or less than 3.61. The composite oxide preferably has an apatite-type crystal structure.

[0057] Among the composite oxides represented by formula (1), M 1 The composite oxide in which La is 9.33+x [T 6.00-y M 2 y ]O 26.0+z It is preferable to use a composite oxide represented by the formula: La 9.33+x [T 6.00-y M 2 y ]O 26.0+z Specific examples of composite oxides represented by the formula are La 9.33+x (Si 5.30 B 0.70 )O 26.0+z , La 9.33+x (Si 4.70 B 1.30 )O 26.0+z , La 9.33+x (Si 4.70 Ge 1.30 )O 26.0+z , La 9.33+x (Si 4.70 Zinc 1.30 )O 26.0+z , La 9.33+x (Si 4.70 W 1.30 )O 26.0+z , La 9.33+x (Si 4.70 Sn 1.30)O 26.0+z , La 9.33+x (Ge 4.70 B 1.30 )O 26.0+z Among the composite oxides represented by formula (1), M 1 Particularly preferred is a composite oxide in which T is lanthanum and T is silicon, that is, a composite oxide containing lanthanum and silicon. The composite oxide represented by formula (1) can be produced, for example, according to the method described in WO 2016 / 111110.

[0058] The solid electrolyte preferably contains not only the above-mentioned composite oxide containing lanthanum and silicon, but also one or more metal oxides selected from the group consisting of yttrium-stabilized zirconia (hereinafter referred to as "YSZ"), samarium-doped ceria (hereinafter referred to as "SDC"), gadolinium-doped ceria (hereinafter referred to as "GDC"), lanthanum gallate, and yttrium-doped bismuth oxide (hereinafter referred to as "YBO"), from the viewpoint of enhancing the oxide ion conductivity of the solid electrolyte layer 50. These metal oxides are chemically stable, and oxygen deficiency is unlikely to occur, particularly when the thin film device 10 is used in a limiting current type oxygen gas sensor, and deterioration of the solid electrolyte layer 50 can be suppressed.

[0059] It is preferable to use YSZ in which the ratio of the number of moles of yttrium to the total number of moles of zirconium (Zr) and yttrium (Y) (Y / (Zr+Y)) is 0.05 or more and 0.15 or less. It is preferable to use SDC in which the ratio of the number of moles of samarium to the total number of moles of cerium (Ce) and samarium (Sm) (Sm / (Ce+Sm)) is 0.10 or more and 0.25 or less. It is preferable to use GDC in which the ratio of the number of moles of gadolinium to the total number of moles of cerium (Ce) and gadolinium (Gd) (Gd / (Ce+Gd)) is 0.10 or more and 0.25 or less. It is preferable to use YBO having a ratio of the number of moles of yttrium to the total number of moles of bismuth (Bi) and yttrium (Y) (Y / (Bi+Y)) of 0.10 or more and 0.30 or less.

[0060] The solid electrolyte layer 50 may contain one of the various materials described above, or may contain two or more of the materials. When two or more materials are used, the materials may be laminated or mixed.

[0061] The thin film device of the present invention can be used as various gas sensors, and is particularly suitable for use as a gas sensor for oxygen, carbon monoxide, carbon dioxide, ammonia, and volatile organic compounds (VOCs).

[0062] Next, a preferred method for manufacturing the thin film device of the present invention will be described by taking as an example a method for manufacturing the thin film device 10 shown in Figures 1 to 4. Figures 6(a) to (h) show a preferred procedure for manufacturing the thin film device 10 shown in Figures 1 to 4. This manufacturing method includes a step of forming a laminated structure on a substrate 11, in which a heater portion 61, a fourth insulating layer 124, a first electrode layer 31, a solid electrolyte layer 50, and a second electrode layer 41 are laminated in this order, to obtain a structure 90, and a step of removing unnecessary portions of the structure 90 to form a bridge structure 20 including a stage 21 supporting the laminated structure and one or more bridges 22 extending from the periphery of the stage 21.

[0063] First, a process for obtaining the structure 90 will be described. This process includes the following steps in this order. 1. Step of forming an insulating layer on the substrate 11 2. Step of forming the heater portion 61 on the insulating layer 3. Step of forming the fourth insulating layer 124 on the sides and above the heater portion 61 4. Step of forming the first electrode layer 31 on the fourth insulating layer 124 5. Step of forming solid electrolyte layer 50 on first electrode layer 31 6. Step of forming second electrode layer 41 on solid electrolyte layer 50 These steps will be described in order below.

[0064] 1. Step of forming an insulating layer on the substrate 11 First, the substrate 11 is thermally oxidized by heating it to 700° C. or higher and 1400° C. or lower in an atmosphere containing oxygen or water vapor, and a first insulating layer 121 and a fifth insulating layer 125 made of SiO2 are formed on the surface of the substrate 11. Next, a second insulating layer 122 and a sixth insulating layer 126 made of SiNx are formed on the surfaces of the first insulating layer 121 and the fifth insulating layer 125 using a thin film forming means described later.

[0065] As a thin film forming means, physical vapor deposition (PVD) methods such as vapor deposition, sputtering, and ion plating, and chemical vapor deposition (CVD) methods can be used. Among them, it is preferable to form the second insulating layer 122 and the sixth insulating layer 126 by using a PECVD (plasma enhanced chemical vapor deposition) method or an LP-CVD (low pressure chemical vapor deposition) method, from the viewpoint of the possibility of adjusting the residual stress and from the viewpoint of mass productivity. 6(a) to 6(i), the first insulating layer 121, the second insulating layer 122, the fifth insulating layer 125, and the sixth insulating layer 126 are omitted from the illustration.

[0066] Next, a third insulating layer 123 is formed on the second insulating layer 122 (FIG. 6(a)). The third insulating layer 123 is formed on the entire surface of the substrate 11. The above-mentioned thin film forming means can be used to form the third insulating layer 123. Among them, when forming the third insulating layer 123 made of SiO2, it is preferable to use the PECVD method from the viewpoint of the ability to adjust residual stress and from the viewpoint of mass productivity.

[0067] 2. Step of forming the heater portion 61 on the insulating layer Prior to the formation of the heater portion 61, the first adhesive layer 64 is formed as necessary. The first adhesive layer 64 can be formed by patterning using a lift-off method. In detail, a layer (not shown) made of photoresist is first provided over the entire area on the third insulating layer 123, and then exposed and developed to form a mask (not shown) having a shape complementary to the shape of the first adhesive layer 64 by patterning. Next, in a state in which the third insulating layer 123 is covered with the mask, the first adhesive layer 64 is formed by a thin film forming means. As the thin film forming means, it is particularly preferable to use a sputtering method from the viewpoint of mass productivity. Finally, the layer made of photoresist is removed to obtain the first adhesive layer 64 having a desired shape.

[0068] Next, the heater section 61 is formed (FIG. 6(b)). In this manufacturing method, in order to simplify the manufacturing process, the heater section 61, heater wiring 62, and heater pad 63 are formed simultaneously. In forming the heater section 61, it is preferable to first form the heater section 61 on the entire surface of the substrate 11 using any of the above-mentioned thin film forming means, and then perform patterning. As a means for forming the thin film, it is particularly preferable to use a sputtering method from the viewpoint of mass productivity. As the patterning method, it is particularly preferable to use a milling method from the viewpoint of suppressing burrs generated at the end of the heater section 61. Also, a lift-off method can be used instead of the milling method. The method of forming the heater section 61 when using the lift-off method is similar to the method of forming the first adhesive layer 64, and therefore the description thereof will be omitted here.

[0069] After forming the heater portion 61, the second adhesive layer 65 is formed as necessary. The second adhesive layer 65 can be formed by the same method as the first adhesive layer 64. It should be noted that the first adhesive layer 64 and the second adhesive layer 65 are omitted in FIGS. 10(b), (g), and (h).

[0070] 3. Step of forming the fourth insulating layer 124 on the sides and above the heater portion 61 After forming the heater portion 61 and, if necessary, the first adhesive layer 64 and the second adhesive layer 65, the fourth insulating layer 124 is formed. The fourth insulating layer 124 is formed on the entire surface of the substrate 11 (FIG. 6(c)). The fourth insulating layer 124 can be formed by the same method as the third insulating layer 123.

[0071] 4. Step of forming the first electrode layer 31 on the fourth insulating layer 124 Next, the first electrode layer 31 is formed on the fourth insulating layer 124. To simplify the manufacturing process, in this manufacturing method, the first electrode layer 31, the first wiring 32, and the first electrode layer pad 33 are simultaneously formed (FIG. 6(d)). The first electrode layer 31, the first wiring 32, and the first electrode layer pad 33 are preferably formed by patterning using a lift-off method. The above-mentioned thin film forming means are used to form the first electrode layer 31, the first wiring 32, and the first electrode layer pad 33. Among them, the sputtering method is preferably used because it is easy to form the first electrode layer 31, the first wiring 32, and the first electrode layer pad 33, which have a cocontinuous structure in which an ion-conductive metal oxide is bonded by platinum or the like, and because it is excellent in mass productivity.

[0072] When the first electrode layer 31, the first wiring 32, and the first electrode layer pad 33 are formed by sputtering, a target of platinum or the like and a target of an ion-conductive metal oxide are used to form the first electrode layer 31, the first wiring 32, and the first electrode layer pad 33 containing platinum or the like and an ion-conductive metal oxide. In addition, by adjusting the gas pressure during sputtering, the porosity of the first electrode layer 31, the first wiring 32, and the first electrode layer pad 33 to be formed can be controlled, and for example, by increasing the gas pressure, the porosity of the first electrode layer 31, the first wiring 32, and the first electrode layer pad 33 can be improved. The respective ratios of platinum or the like and the ion-conductive metal oxide in the first electrode layer 31, the first wiring 32, and the first electrode layer pad 33 can be adjusted by appropriately setting the power supplied to the target when performing the sputtering method.

[0073] 5. Step of forming solid electrolyte layer 50 on first electrode layer 31 The solid electrolyte layer 50 is formed on one of the two surfaces of the first electrode layer 31 that does not face the substrate 11 (FIG. 6(e)). The solid electrolyte layer 50 is formed to a size that extends from the periphery of the first electrode layer 31 and covers a part of the first wiring 32. As in the formation of the first electrode layer 31, the solid electrolyte layer 50 can also be formed preferably by combining the lift-off method with the above-mentioned thin film forming means. Of the above-mentioned thin film forming means, it is preferable to use the sputtering method, because it is easy to form the solid electrolyte layer 50 having the desired composition and has excellent mass productivity.

[0074] 6. Step of forming second electrode layer 41 on solid electrolyte layer 50 In this manufacturing method, in order to simplify the manufacturing process, the second electrode layer 41, the second wiring, and the pad for the second electrode layer 43 are formed simultaneously to obtain a structure 90 ( FIG. 6( f) ). The second electrode layer 41, the second wiring, and the pad for the second electrode layer 43 are formed by the same method as the first electrode layer 31, the first wiring 32, and the pad for the first electrode layer 33. The second electrode layer 41 is formed to a size such that it does not extend beyond the periphery of the solid electrolyte layer 50.

[0075] Next, a process for forming bridge structure 20 after obtaining structure 90 by the above-mentioned method will be described. First, unnecessary portions of the first insulating layer 121, the second insulating layer 122, the third insulating layer 123, and the fourth insulating layer 124, which are insulating layers located above the substrate 11, are removed (FIG. 6(g)). The unnecessary portions here refer to portions of the target thin-film device 10 (FIG. 1) that do not overlap with the bridge structure 20 or the peripheral portion 24 in a plan view. In this step, in parallel with removing the unnecessary portions, a part of the fourth insulating layer 124 formed on the heater pad 63 can be removed to expose the heater pad 63 to the outside.

[0076] The unnecessary portions can be removed by an etching method such as a dry etching method or a wet etching method. Dry etching can be performed using reactive ion etching (RIE) with fluorocarbon or halogen gas, while wet etching can be performed using isotropic etching with hydrofluoric acid, nitric acid, sulfuric acid, phosphoric acid, etc., or anisotropic etching with alkaline solutions such as KOH (potassium hydroxide), TMAH (tetramethylammonium hydroxide), and EDP (ethylenediamine pyrocatechol). Among these, from the viewpoint of preventing etching of the structure 90, RIE can be preferably used.

[0077] Next, unnecessary portions of the fifth insulating layer 125 and the sixth insulating layer 126, which are insulating layers located below the substrate 11, are removed, and then unnecessary portions of the substrate 11 are removed (FIG. 6(h)). The unnecessary portions here refer to portions that do not overlap with the peripheral edge portion 24 in a plan view.

[0078] The method for removing the unnecessary portions can be the same as the method for removing the insulating layer located above the substrate 11. In particular, RIE can be preferably used as a method for removing unnecessary portions of the insulating layer located below the substrate 11. Also, deep recess etching (DRIE) can be preferably used as a method for removing unnecessary portions of the substrate 11, in which an etching process using SF6 (sulfur hexafluoride) and a passivation process using a fluoroalkane gas such as C4F8 (octafluorocyclobutane) are alternately performed.

[0079] Although the thin film device and the method for manufacturing the same of the present invention have been described based on the preferred embodiments thereof, the present invention is not limited to such embodiments. For example, the number of turns of the filament constituting the heater section 61 may be less than or more than the number of turns of the filament shown in FIG. In the above-described embodiment, as shown in FIG. 3 , the second wiring 42 and the pad 43 for the second electrode layer are arranged so as to be in contact with the third insulating layer 123. Alternatively, however, the solid electrolyte layer 50 may be arranged between the second wiring 42 and the pad 43 for the second electrode layer and the third insulating layer 123. 3 and 4, the upper surface of the fourth insulating layer is flat, but the upper surface of the fourth insulating layer does not have to be flat. For example, the upper surface of the fourth insulating layer may be higher in a portion where the heater section 61 is present than in a portion where the heater section 61 is not present. Similarly to the first electrode structure 30, the second electrode structure 40 may include a porous body in at least a portion thereof.

[0080] The above-described embodiment of the present invention encompasses the following technical ideas. [1] A thin-film device having a bridge structure including a stage and one or more bridges extending from a periphery of the stage, An electrode unit and a heater unit are disposed on the stage, the electrode portion includes a first electrode layer, a solid electrolyte layer disposed on the first electrode layer, and a second electrode layer disposed on the solid electrolyte layer; A thin film device, wherein the electrode portion and the heater portion do not overlap when the bridge structure is viewed in a plan view. [2] The heater part is made of a single filament, At least two of the bridges extend from a periphery of the stage; the filament arranged in the heater section extends to the two bridges and to a peripheral portion connected to the bridges and surrounding the stage, The electric resistance R of the wire placed on the stage S is the electrical resistance R of the wire extending to the bridge and the peripheral portion. B The thin film device according to claim 1, [3] The thin-film device has a first electrode structure; the first electrode structure includes the first electrode layer and a first wiring extending from a periphery of the first electrode layer, the first wiring is disposed on the stage and the bridge, the first wiring has a diffusion rate controlling layer at a portion of the first wiring that is disposed on the stage, the first electrode structure includes a porous body in at least a portion thereof; The thin-film device according to [1] or [2], wherein the heater section is disposed so that a heating temperature of the first electrode layer is higher than a heating temperature of the diffusion-controlling layer. [4] when the diffusion-controlling layer is cut perpendicular to the gas diffusion direction to obtain a cross section of the first electrode structure, the minimum cross-sectional area at the portion where the area of ​​the cross section is the smallest is defined as Sr; When the area of ​​a region where the first electrode layer and the second electrode layer overlap in a plan view is Sp, Sr / Sp is 1.0×10 -7 More than 6.9 x 10 -4 A thin film device according to [3], [5] The electrode portion has a circular, elliptical, or polygonal shape in a plan view, The thin film device according to any one of [1] to [4], wherein the distance between the centroid of the electrode portion and the centroid of the heater portion in a plan view is 300 μm or less. [Explanation of symbols]

[0081] 10 Thin-film devices 20 Bridge structure 21 Stage 22 Bridge 24 Periphery 26 Electrode section 30 First electrode structure 31 First electrode layer 32 First wiring 40 Second electrode structure 41 Second electrode layer 42 Second wiring 50 Solid electrolyte layer 61 Heater section P diffusion-controlling layer

Claims

1. A thin film device having a bridge structure including a stage and one or more bridges extending from a periphery of the stage, An electrode unit and a heater unit are disposed on the stage, the electrode portion includes a first electrode layer, a solid electrolyte layer disposed on the first electrode layer, and a second electrode layer disposed on the solid electrolyte layer; A thin film device, wherein the electrode portion and the heater portion do not overlap when the bridge structure is viewed in a plan view.

2. The heater portion is made of a single filament, the filament arranged in the heater section extends to the bridge and a peripheral portion connected to the bridge and surrounding the stage, The electric resistance R of the wire placed on the stage Ｓ is the electrical resistance R of the wire extending to the bridge and the peripheral portion. Ｂ The thin film device of claim 1 ,

3. The thin film device has a first electrode structure; the first electrode structure includes the first electrode layer and a first wiring extending from a periphery of the first electrode layer, the first wiring is disposed on the stage and the bridge, the first wiring has a diffusion rate controlling layer at a portion of the first wiring that is disposed on the stage, the first electrode structure includes a porous body in at least a portion thereof; The thin-film device according to claim 1 , wherein the heater portion is disposed so that a heating temperature of the first electrode layer is higher than a heating temperature of the diffusion-controlling layer.

4. When the diffusion-controlling layer is cut perpendicular to the gas diffusion direction to obtain a cross section of the first electrode structure, the minimum cross-sectional area at a portion where the area of ​​the cross section is minimum is defined as Sr, When the area of ​​a region where the first electrode layer and the second electrode layer overlap in a plan view is Sp, Sr / Sp is 1.0×10 －７ Above 6.9 x 10 －４ 4. The thin film device of claim 3, wherein:

5. The electrode portion has a circular, elliptical, or polygonal shape in a plan view, The thin film device according to claim 1 , wherein the distance between the centroid of the electrode portion and the centroid of the heater portion in a plan view is 300 μm or less.

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