JP2007017263A - Sensing element, vacuum gauge and vacuum tube - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sensing element, a vacuum gauge and a vacuum tube which can catch heat diffused 3-dimensionally with a 3-dimensional temperature sensing part, catch the 3-dimensional isothermal contour with the temperature sensing part, to arrange the distance between the heater and the sensing part closer than the distance between the heater and a substrate and to relate to a phenomenon concerning a solid space having heat in the element. <P>SOLUTION: The sensing element comprises a substrate 10 having a penetration hole and a hollow 11, a heater part 13 provided so as to bridge the penetration hole or the hollow 11 having a heating electrode 13-1 having a shape of a bent cantilever and electing into a space, and temperature sensing part 14 and 15 having temperature sensing electrodes 14-1 and 15-1 having a shape of a bent cantilever on the penetration hole or a hollow and erecting into a space. The sensing element measures heat transported from the heater part with the temperature sensing part. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a sensing element, a vacuum gauge, and a vacuum tube, and more particularly, to a thermal flow meter used for measurement of gas flow velocity and flow rate.

  Conventionally, as a means for measuring the flow velocity / flow rate of a fluid and the components / concentrations of an atmosphere, there is a method of detecting and measuring the heat carried to the fluid or the heat propagated to the atmosphere. The sensor, which is a detection unit in a thermal flow meter using this method, has a heater as a heat source upstream of the gas flow, a temperature sensing unit downstream, and the amount of heat transmitted to the downstream side (temperature change) Measure the flow velocity and flow rate as the amount) or the time required for transmission. In addition, a sensor that is a detection unit in a hygrometer or a gas chromatograph transmits or transmits the amount of heat (temperature change amount) that is propagated by the thermal conductivity that is given according to the components and concentration of the atmosphere from a heater that is a heat source in the atmosphere. Measure humidity, gas composition and concentration as required time. In this case, the thermal response is accelerated by reducing the heat capacity of the heating source and the temperature sensing part of the sensor, which is the detection part, and by bringing them in close proximity, thereby causing rapid fluctuations, minute flow rates / flow rates, trace components, and trace amounts. The concentration can be detected. This sensor is realized by means of microfabrication technology for producing an integrated circuit. Such a sensor is called a flow sensor or a flow velocity sensor, a heat-conducting humidity sensor, or a heat-conducting gas sensor, and some have been conventionally proposed.

  As one of them, the flow sensor of Patent Document 1 has a substrate having a through hole or a cavity, a film heater unit and a film detection unit bridged in a doubly-supported or cantilever type on the through-hole or the cavity. Furthermore, the heater part and the detection part are laminated in two or more layers along the flow direction of the fluid to be measured, and have a space between the layers. By forming this space with a film thickness, it can be formed at a very small interval and with high accuracy, and the spatial distance between the film heater unit and the film detection unit is reduced, resulting in high speed response, high accuracy, and minute flow rate. Aiming for high efficiency.

  Patent Document 2 discloses that the shape of the heater wire is circular and the isothermal curve of the temperature distribution due to the heat generated by the heater wire is concentric, and two temperature sensors are provided on both sides of the circular shape of the heater wire. The shape of the line is also circular, and regardless of the direction of fluid movement, the spread shape of the isothermal curve that occurs is always uniform with respect to the heater wire and the temperature sensor wire. There is described a flow sensor that can detect the flow velocity or flow rate without dependence on the movement direction of the fluid, and without dependence on the movement direction of the fluid. Specifically, the heater and the temperature sensing unit are arranged adjacent to each other on the plane, and the heat of the gas heated in accordance with the upstream heater heat generation and the flow rate, that is, the amount of heat transferred is measured by the temperature sensing unit on the downstream plane side. A flow sensor is described in which the temperature sensor line has a shape corresponding to the shape of the isothermal line of the temperature distribution of the heat from the heater line. According to Patent Document 2 having such a configuration, since the temperature sensor line has a shape corresponding to the shape of the isothermal line of the temperature distribution due to the heat generated by the heater line, A slight movement can be detected in almost the entire region of the temperature sensor line, and a more sensitive flow sensor can be provided.

  In order to capture the three-dimensionally diffused heat according to Patent Documents 1 and 2 described above, the temperature-sensitive part may be formed in three dimensions and the heater surrounded by the temperature-sensitive part, and is not easily affected by the substrate surface. Since it is necessary to detect the flow of the place, it can be seen that the temperature sensing part may be formed at a place away from the substrate. Furthermore, it turns out that a three-dimensional temperature-sensitive part structure is required.

For this purpose, Patent Document 3 has been proposed as a three-dimensional technique required. According to Patent Document 3, the sputter deposition film stress is compressive at a low plasma gas pressure, and the film stress in the deposition sublayer changes with respect to the tensile stress when the plasma gas pressure increases. In addition, the intrinsic stress of many sputtered thin films depends on the ambient pressure at which the material is deposited. By changing the pressure during sputtering, the obtained thin film is subjected to compressive stress (tensile force) near the substrate-film interface. A tensile stress (compressive force) is applied on the film surface. Furthermore, the lower gold layer forms the outer skin of the coil when released, and the lease layer is removed by wet undercut etching. Further, KOH (wet process) is applied to the etchant that can be applied to the Si release layer, and when the release window is removed, the elastic member is rolled up by itself due to the inherent stress profile of the elastic member. A new kind of high Q varicap can be manufactured using such a technique. These varicaps use the same microspring technology described above, have the required capacitance values, and are further integrated on the chip. An on-chip RF passive element, inductor, and varicap that are missing due to a microspring-based varicap structure can be fabricated by the same process technology. These microspring varicaps have the added advantage of requiring a lower bias voltage than parallel plate MEMS capacitors. By using a spring as the second electrode of the photolithographic patterning capacitor and changing the voltage between the fixed plate and the spring, the capacitance of the varicap structure is changed.
Patent No. 3,049,122 Japanese Patent Laid-Open No. 11-118553 Special table 2003-533897 gazette

  However, according to Patent Document 1, the heat of the upstream heater diffuses three-dimensionally toward the downstream side, but the flow is narrowed so that there is no three-dimensional diffusion of the flow. However, since the flow path is a solid with higher thermal conductivity than the fluid, the heat flow to the inner wall is increased by narrowing the flow path. Measurement was difficult. In addition, since the heat capacity is large, heat is stored in the substrate, and heat dissipation from the heat storage is added to the flow, which affects the downstream temperature sensing part. In addition, since it is formed in close proximity with high accuracy, there may be a relatively small effect. However, with regard to the positional relationship between the heater, the temperature sensing part, and the substrate, the distance between the heater and the temperature sensing part is the It is necessary that the heater and the temperature sensing unit be as far as possible from the substrate.

  Moreover, in patent document 2, the flow detected by the sensor is the substrate surface, not the flow that must be measured. More precisely, it is necessary to detect a flow in a place that is not easily affected by the substrate surface. The closer to the surface of the substrate, the more difficult it is to flow due to the viscosity of the gas. Therefore, the closer the distance from the substrate, the greater the interference and the minute flow rate cannot be measured. It is difficult to measure a highly viscous fluid, and it is difficult to measure in a temperature range where the viscosity becomes high. The heater and the temperature sensing part are arranged adjacent to each other on the plane, and the heat of the gas heated according to the upstream heater heat generation and flow rate, that is, the amount of heat carried is captured as the temperature rise of the temperature sensing part on the downstream plane side. The temperature sensor line is characterized by having a shape corresponding to the shape of the isothermal line of the temperature distribution of the heat from the heater line, but the heater and the temperature sensing part are arranged on the same plane, and the upstream Since the heat of the heater on the side diffuses three-dimensionally toward the downstream side, only one plane component of the thermal diffusion component can be captured in the temperature sensing part, and the transmission efficiency is low and the sensitivity is also low, resulting in low noise and high noise. A resolution signal processing circuit is required. In addition, since there is a great influence if there is a turbulent element, it is necessary to capture the three-dimensional isotherm at the temperature sensing part.

  Furthermore, Patent Document 3 discloses a three-dimensional structure coil on a chip, but it is used for a variable capacitor, an electromagnetic coil, and a contact, and is not a heater and a temperature sensitive part for a heat transport mechanism. Since the functions are different as described above, the materials, shapes, and arrangements are different, but a new configuration needs to be added to the heater and the temperature sensing unit based on the heat transport mechanism. As a sensor that measures the flow rate of fluid and the flow rate in the pipe using a heat transport mechanism, the distance between the heater and the temperature sensing unit is closer than the distance between the heater and the substrate, and the heater and the temperature sensing unit are as far as possible from the substrate. Need to be. As much as possible, it is necessary to capture the three-dimensional isotherm in the temperature-sensitive part from the three-dimensionally diffused heat.

  The present invention is for solving these problems, and the three-dimensional temperature sensing part captures three-dimensionally diffused heat, the three-dimensional isotherm catches by the temperature sensing part, and the heater part and the temperature sensing part. It is an object of the present invention to provide a sensing element, a vacuum gauge, and a vacuum tube that can be closer to the distance between the heater part and the substrate and can participate in a phenomenon related to a three-dimensional space having heat as an element.

  In order to solve the above problems, the sensing element of the present invention is provided so as to be bridged on a substrate having a through hole or a cavity and a through hole or a cavity, and is formed into a curved and cantilever shape and in a space. A heater part having a heating electrode standing up and a temperature sensing part having a temperature sensing electrode standing in the space while being bent and cantilevered on a through hole or cavity. And the detection element of this invention measures the heat amount conveyed from a heater part by a temperature sensing part. Therefore, the amount of heat diffused three-dimensionally can be captured by the three-dimensional temperature sensing unit, so that a three-dimensional isotherm can be captured by the temperature sensing unit, and the distance between the heater unit and the temperature sensing unit is the heater unit and the substrate. Can be closer than the distance.

  In addition, the heater part and the temperature sensitive part are arranged adjacent to each other, and the amount of heat transported by the fluid from the heater part according to the flow rate / flow rate of the fluid or the thermal conductivity of the atmosphere is measured by the temperature sensitive part. Can be manufactured by plane processing by arranging them in parallel, and can be used as a flow sensor for measuring the flow velocity and flow rate of the fluid.

  Furthermore, the flow velocity is measured by the distance between the heater portion and the temperature sensing portion and the heat transfer time transported by the fluid from the heater portion in accordance with the flow velocity / flow rate of the fluid or the thermal conductivity of the atmosphere. Therefore, it is possible to provide a sensor capable of measuring the heat transfer time and calculating the flow velocity.

  Moreover, it is preferable that the heating electrode and the temperature-sensitive electrode have a shape along a pipe-shaped curved surface.

  Furthermore, since the heater part is arranged inside the temperature sensing part along the flow of the fluid, the distance between the heater part and the temperature sensing part can be made closer for fine detection.

  Moreover, the direction of the fluid flow can be detected by arranging the heater unit inside the temperature sensing unit along the direction crossing the fluid flow.

  Furthermore, the temperature sensing electrode of the temperature sensing part is arranged in an annular shape, and the heating electrode of the heater part is arranged at the center of the annular temperature sensing part, so that it fluctuates even if there is a deviation in the angle of the flow direction. And can be measured under turbulent flow conditions.

  In addition, the first substrate in which the heater part is disposed in the cavity region and the second substrate in which the temperature sensing unit is disposed in the cavity region are integrally joined with the cavity regions facing each other, thereby providing a structure or A sensing element having a high degree of freedom in shape can be provided.

  Furthermore, the sensing element of the present invention includes a substrate having a through-hole or a cavity, and a resistor having an electrode that is provided so as to bridge over the through-hole or the cavity, has a curved and cantilever shape, and stands in space. It has. Then, a heating current is supplied to the resistor at the heating timing to cause the resistor to generate heat, and a detection current is supplied to the resistor at the detection timing to change the resistance value of the resistor at the time of detection from the resistance value of the resistor at the time of heating. The amount of heat transported is calculated based on the subtraction value obtained by subtracting. Therefore, there is little loss due to heat transfer, and the heater part and the temperature sensing part are in a shape that spreads in the flow, so even if the flow shifts in the range of angle θ on the xy plane and the zy plane. There is little influence and the tolerance is wide.

  In addition, the sensing element of the present invention includes a substrate having a through hole or a cavity, and a resistor that is provided so as to bridge over the through hole or the cavity and has an electrode having an inclined shape. Then, a heating current is supplied to the resistor at the heating timing to cause the resistor to generate heat, and a detection current is supplied to the resistor at the detection timing to change the resistance value of the resistor at the time of detection from the resistance value of the resistor at the time of heating. The amount of heat transported is calculated based on the subtraction value obtained by subtracting. Therefore, there is little loss due to heat exchange.

  Furthermore, the sensing element of the present invention includes a substrate having a through hole or a cavity, a first resistor having an inclined electrode provided so as to be bridged on the through hole or the cavity, and the through hole or the cavity. And a second resistor having an electrode having an inclined shape. Then, the amount of heat transported from the first resistor is measured by the second resistor, or the amount of heat transported from the second resistor is measured by the first resistor. Therefore, there is little loss due to heat transfer, and measurement can be performed according to the direction of flow.

  Further, a vacuum gauge as another invention encloses the above-described sensing element in a vacuum container, and draws a wire from each electrode pad of the heater part and the temperature sensing part to the outside of the vacuum container, so that the gas inside the vacuum container is drawn. The pressure dependency of the thermal conductivity is converted to a degree of vacuum as the temperature fluctuation obtained from the temperature sensitive part. Therefore, the thermal conductivity detection type pressure and vacuum degree can be measured.

  Furthermore, a vacuum tube as another invention encloses the above-described sensing element in a vacuum vessel, draws wiring from each electrode pad and substrate of the heater portion and the temperature sensing portion to the outside of the vacuum vessel, makes the heater portion a filament, Using the grid as the hot part and the substrate as the collector, the current flowing between the filament and the collector is measured and converted into a degree of vacuum. Therefore, it is possible to provide a triode vacuum tube that can efficiently capture thermoelectrons even when the heat generation temperature is lowered.

  According to the detection element of the present invention, the heater section has a heating electrode that is bent and cantilevered and has a heating electrode that stands in the space, and is provided so as to bridge over a through-hole or a cavity provided in the substrate. . In addition, the temperature-sensing part has a temperature-sensing electrode which is bent and cantilevered on the through-hole or cavity, and has a temperature-sensitive electrode standing in the space, and is provided so as to be bridged on the through-hole or cavity provided in the substrate ing. And the detection element of this invention measures the heat amount conveyed from a heater part by a temperature sensing part.

  FIG. 1 is a perspective view showing a configuration of a sensing element according to the first embodiment of the present invention. The sensing element 100 according to the present embodiment shown in the figure includes a substrate 10 and a heater unit 13 and two elements disposed on a bridge 12 provided to bridge the cavity 11 provided in the substrate 10. The temperature sensing units 14 and 15 are included. The two temperature sensing parts 14 and 15 are arranged in parallel on both sides of the heater part 13, and the temperature sensing electrodes 14-1 and 15-1 constituting the temperature sensing parts 14 and 15 are pipe-shaped. Are formed along the curved surface and are opposed to each other. The heating electrode 13-1 of the heater unit 13 is connected to a power supply lead wire 13-2, and each power supply lead wire 13-2 is provided with an electrode pad 13-3. The heater unit 13 is an electrode pad. Joule heat is generated by power supply from 13-3. Further, the detection lead wires 14-2 and 15-2 are connected to the terminals of the temperature sensing electrodes 14-1 and 15-1 constituting the temperature sensing portions 14 and 15, respectively. -2 are provided with electrode pads 14-3 and 15-3, respectively. Further, the temperature sensitive parts 14 and 15 have temperature-dependent characteristics due to heat conduction from a nearby space. In the flow along the x-axis, the heat of the heater unit 13 installed upstream is diffused into the space according to the flow velocity, and is captured by the temperature sensing units 14 and 15 along the pipe-shaped curved surface. The flow velocity and flow rate of the fluid flowing through each of the pipe-shaped temperature sensitive portions 14 and 15 formed by the temperature sensitive electrodes 14-1 and 15-1 are measured. The direction of thermal diffusion not only follows the flow in the x-axis direction but diverges in a three-dimensional direction. In the flow along the x-axis, the temperature sensitive parts 14 and 15 are three-dimensionally arranged with respect to the heater part 13, so that the temperature sensitive parts 14 and 15 perform heat diffusion from the heater part 13 in a three-dimensional space. Since it is captured, heat transfer efficiency is large. Although the fluid has a lower flow velocity near the substrate surface due to friction than a location far from the surface, the heater unit 13 and the temperature sensitive units 14 and 15 stand on the substrate 10 and are separated from the substrate surface. Compared with the case where it is arranged, it is possible to measure even at a very low flow rate, while there is less influence of turbulent flow due to separation of the flow from the surface even at a high flow rate. The point that it is advantageous to move away from the substrate surface when measuring this minute flow velocity will be explained. FIG. 2 shows the air flow velocity measurement characteristics at a distance along the substrate surface from the substrate end surface and at a distance away from the substrate surface. Thus, in order to measure the flow velocity of air, it is necessary to move away from the substrate surface, and at the flow velocity measurement location that is smaller than the boundary layer thickness, the dependency of the physical property value of the fluid and the substrate structure affect each other in a complex manner. In order to obtain the flow velocity, it is necessary to correct the measurement value, and uncertainty for that is added. Therefore, in order to measure the minute flow velocity, it is more advantageous to move away from the substrate surface. In accordance with Stokes' law, the laminar velocity is obtained by the boundary layer thickness δ ≠ 5 * (vx / U) ^ (1/2) that receives the frictional resistance of the wall. However, v = η / ρ, η: kinematic viscosity coefficient, ρ: density, x: distance from the end face, U: flow velocity.

  In addition, the temperature sensing unit 14 upstream of the heater unit 13 captures the first temperature information of the fluid when using the temperature characteristics of the temperature sensing material, or measurement for the case where the flow is reversed. Although it is a means, the temperature sensing part 14 can catch the thermal diffusion from the heater part 13 in three-dimensional space. In the case of being arranged on the substrate surface, if the angle changes with respect to the flow, the sensitivity is sensitively affected, and the maximum sensitivity can be obtained only in one direction. 14 and 15 are three-dimensionally arranged with respect to the heater unit 13, there is a margin in the angle adjustment value for the flow, and even if the flow along the x axis is angled, it can be captured in three dimensions, so the alignment of the flow axis and sensor arrangement Becomes easy. Furthermore, the heat flow differs greatly between the upward and downward postures. Since the warmed gas rises, if the substrate is directed to the lower surface, heat accumulation is generated in the cavity, and if the substrate is directed to the upper surface, heat accumulation is not generated in the cavity. Since the warm parts 14 and 15 stand on the substrate 10 and are separated from the surface of the substrate, the influence of the substrate 10 is small, and the number of mounting locations increases.

Next, even if the heater part 13 and the temperature sensitive parts 14 and 15 are three-dimensional structures, they can be manufactured by plane processing, and the manufacturing method will be described with reference to FIGS. 3 to 5 which are manufacturing process diagrams. 3 (a) and 5 (a) are plan views, FIG. 4 (b) is a side view, and FIG. 5 (b) is a cross-sectional view taken along line AA ′ of FIG. 5 (a). FIG. 5C is a cross-sectional view taken along the line BB ′ of FIG. The same reference numerals as those in FIG. 1 denote the same components.
First, as shown in FIG. 3, on the substrate 10, the heating electrode 13-1 and the power supply lead 13-2 of the heater unit 13, the temperature sensing electrodes 14-1 and 15-1 of the temperature sensing units 14 and 15, and the detection lead The conductive material films of the lines 14-2 and 15-2 and the electrode pads 14-3 and 15-3 are patterned. Here, the heater part 13 and the temperature sensitive parts 14 and 15 use a metal material such as Pt or W as a material having a large resistance temperature coefficient. Further, since the power supply lead wire 13-2 and the detection lead wires 14-2 and 15-2 are also formed of the same material, they can be formed simultaneously and are simple. And since the electric resistance value of the power supply lead wire 13-2 and the detection lead wires 14-2 and 15-2 must be lowered so as not to generate heat, the width is wide in the direction in which the current flows and the heat capacity is reduced. It arrange | positions on the board | substrate 10 in order to increase. In addition, you may form the temperature sensitive parts 14 and 15 with the thermoelectric material which has a Seebeck effect. In the case of this thermoelectric material, the cold junction is arranged in a region without a cavity on the substrate 10.

  And as shown to (a) of FIG. 4, the insulating layer of the area | region of the heat generating electrode 13-1 of the heater part 13 on the board | substrate 10 and the temperature sensitive electrodes 14-1 and 15-1 of the temperature sensitive parts 14 and 15 is formed. When the etching is removed, as shown in FIG. 4B, the heater portion 13 and the temperature sensitive portions 14 and 15 are cantilevered because the lower layer is not in close contact with each other. To stand up. In this etching of the insulating layer, the insulating layer below each pattern wraps around from the edge of the insulating layer to a distance that is ½ of the pattern width of the heater 13 and the temperature sensitive parts 14 and 15. By performing the cut etching, the heater part 13 and the temperature sensitive parts 14 and 15 can be bent and cantilevered.

  Further, as shown in FIG. 5A, only the exposed region of the substrate surface where the insulating layer has been removed by etching is etched to form the cavity 11. As can be seen from (b) of FIG. 4, the structure stands up on the substrate 10 and may have the structure. However, the structure shown in (b) and (c) of FIG. 5 is compared with (b) of FIG. Since the heater unit 13 and the temperature sensing units 14 and 15 are further away from the substrate 10 having a large heat capacity, the influence of heat from the substrate 10 becomes smaller and more effective in the heat transfer of the fluid. By etching the substrate 10 using a known technique, the etching proceeds to the inside of the edge of the insulating layer indicated by a broken line in the figure, so that a bridge 12 is formed on the cavity 11 and the temperature sensing parts 14 and 15 of the cantilever are It will be supported by the doubly supported beams of the bridge 12.

Here, a method of forming a three-dimensional temperature sensing portion will be described with reference to FIG. For example, the lower layer 21 is first formed on the heat-resistant substrate 20 such as Si, Al, Cu, Ni, Cr, stainless steel, Kovar, Mo, W, Al ₂ O ₃ , SiO ₂ , glass, ceramic, epoxy resin, polyimide resin or the like. As an insulating material such as SiO ₂ , MgO, Al ₂ O ₃ , Ta ₂ O ₅ , and TiO ₂ , the film is formed by using a film forming method such as vapor deposition, sputtering, CVD, or the like at about 0.3 to 3 μm. In this film formation, the degree of vacuum is preferably 10 ⁻⁶ to 10 ⁻³ Torr or less, and the film is formed in a high vacuum atmosphere so that the density does not increase and shrink in the baking process described later, and the film is as empty as possible. It is necessary to reduce the porosity so as to increase the density. Next, a conductive resistance heating material such as NiCr, Ir, Pt, Ir—Pt alloy, SiC, TaN, and Kanthal alloy constituting the heating element layer and the extraction electrode as the upper layer 22 is deposited by about 0.1 to 3 μm. The film is formed by sputtering or the like. The upper layer 22 is photoetched into a predetermined shape to form a pattern. Furthermore, when the protective coating layer 23 is laminated, an electrical insulating material equivalent to that of the lower layer 21 may be used and the film may be formed under the same conditions. Here, since the upper layer 22 and the protective coating layer 23 are continuously formed from the lower layer 21, the roughness of the surface state and the level difference increase, and the particle size increases as the film thickness increases, and it contains many holes and defects. Therefore, it is possible to further shrink from the lower layer after the baking treatment, and the beam portion can be bent. Further, when the upper layer 22 and the protective coating layer 23 are formed, if the degree of vacuum is lowered to about 10 ⁻⁴ to 10 ⁻² Torr than when the lower layer is formed, the number of holes is increased. A film quality can be obtained, which can also be shrunk after baking. Next, when the cavity portion 24 is formed in the substrate 20 by etching, a beam portion composed of the lower layer 21 and the upper layer 22 or a beam portion composed of the lower layer 21, the upper layer 22, and the protective coating layer 23 is formed. Furthermore, if this is baked at 350-800 degreeC, a predetermined curvature curve shape will be obtained. Even if baking is performed before the cavity 24 is formed, the force constrained from the substrate 20 by the force to shrink the upper layer 22 and the protective coating layer 23 after the cavity is formed disappears. A shape is obtained. Therefore, the order of the baking process and the formation of the cavity portion 24 is possible without specifying.

  Next, as a method for measuring the flow rate of the fluid, there is a thermal tracer method, which will be outlined. For example, as described in Japanese Patent Application Laid-Open No. 60-186714, a heater that generates a predetermined heat pulse and applies the fluid to a fluid is provided in a pipe through which the fluid flows, and is downstream at a predetermined distance from the heater. There is a flow rate measuring device provided with a temperature detector at a position. This gives a heat pulse to the flowing fluid, and detects the maximum temperature of the heat distribution that has moved along the flow at a predetermined position. Then, the flow rate of the fluid is obtained using the time from when the heat pulse is applied to when the maximum temperature is detected.

  FIG. 7 is a plan view showing the configuration of the sensing element according to the second embodiment of the present invention. In the figure, the same reference numerals as those in FIG. 1 denote the same components. In the detection element 200 of the second embodiment shown in the figure, a plurality of temperature sensing parts 15 are arranged in parallel and the heater part 13 is heated intermittently, so that the heat waves are sensed at a predetermined distance. The time to reach the warm section 15 is captured and the flow velocity is measured.

  Next, FIG. 8 is a perspective view showing a configuration of a sensing element according to the third embodiment of the present invention. The detection element 300 of the third embodiment shown in the figure is configured by disposing a heater unit 13 at the x-axis position inside each of the two temperature sensing units 14 and 15 standing on the substrate 10. ing. The flow component in the figure is guided along the x-axis, and heat is applied from the heater unit 13. Since the direction of thermal diffusion not only follows the flow but also diverges in a three-dimensional direction, the temperature sensing units 14 and 15 can capture the thermal diffusion of the heater unit 13 in a three-dimensional space. In this case, since the heat generating part of the heater unit 13 is located inside the flow more than the temperature sensing units 14 and 15, even if the flow along the x axis is angled, it can be captured in three dimensions, so the flow axis and the sensor arrangement are aligned. Is easy. Since the heater unit 13 and the temperature sensing units 14 and 15 as in the first and second embodiments can be made closer to each other than the parallel flow sensor structure, the minute flow rate is reduced. Highly effective in detecting

  Here, the manufacturing process of the sensing element of the third embodiment will be described with reference to FIGS. 9 and 10 showing the manufacturing process. 9 and 10A are plan views, and FIG. 10B is a cross-sectional view taken along the line C-C ′ of FIG.

  As shown in FIG. 9, since the heater unit 13 is superposed on the temperature sensitive units 14 and 15, the heater unit 13 needs to be formed in the next process using a sacrificial layer. Therefore, first, the conductive material films of the temperature sensitive electrodes 14-1, 15-1, the detection lead wires 14-2, 15-2, and the electrode pads 14-3, 15-3 of the temperature sensitive parts 14, 15 are formed on the substrate 10. Form a pattern. The heater part 13 and the temperature sensitive parts 14 and 15 use a metal material such as Pt or W as a material having a large resistance temperature coefficient. Next, a sacrificial layer, such as Ni, that can be selectively etched away later is formed in a pattern in a region to be the heater portion 13. Next, the conductive material films of the heating electrode 13-1, the power supply lead wire 13-2, and the electrode pad 13-3 of the heater section 13 are formed in a pattern. Then, the sacrificial layer in the region of the heater unit 13 on the substrate 10 and the insulating layer in the region of the heater unit 13 and the temperature sensitive units 14 and 15 are removed by etching, and only the exposed region of the substrate surface is etched to form the cavity 11. To do. As shown in FIG. 10, the heater unit 13 and the temperature sensitive units 14, 15 are not cantilevered in the lower layer and become cantilever beams, so that a curved surface is formed by the warping and bending effect and stands on the substrate 10. The heat of the heater unit 13 at the axial position of the temperature sensitive units 14 and 15 is captured. As shown in FIG. 10 (b), the heater unit 13 is a double-supported beam structure that connects the cantilever beam structures, so the portion of the double-supported beam structure has little warping and bending effect and is close to a straight line.

  FIG. 11 is a perspective view showing a configuration of a sensing element according to the fourth embodiment of the present invention. The sensing element 400 according to the fourth embodiment has a flow sensor structure in which a heater portion 41 is arranged inside the temperature sensing portion 40, similarly to the sensing element 3 according to the third embodiment shown in FIG. However, the operation is different, and the flow is guided to the yz plane, and is caused to flow substantially perpendicularly to the pipe-shaped temperature sensing unit 40 and the heater unit 41. Since the heater portion 41 is located at the pipe shaft position, there is little influence even if the flow shifts in the range of the angle θ on the zy plane. The allowable range of the angle shift in the xy plane is wide since the temperature sensing unit 40 is laterally expanded. Further, since the temperature sensing portion 40 has a skewer shape, there is a rectifying action, a stable output can be obtained even under turbulent conditions, and a rectifying element is unnecessary.

  Here, the manufacturing process of the sensing element of the fourth embodiment will be described with reference to FIG. 12 showing the manufacturing process. 1A is a plan view, FIG. 1B is a cross-sectional view taken along the line DD ′ of FIG. 1A, and FIG. 2B is an E-line of FIG. It is E 'line sectional drawing. In the manufacturing process of the sensing element of the third embodiment shown in FIG. 8, the heater part 13 is superposed on the temperature sensitive parts 14 and 15, so the heater part 13 is formed in the next process using a sacrificial layer. There was a need to do. However, since it is sufficient that the heater portion 13 is provided inside the temperature sensitive portions 14 and 15 at the time of standing on the substrate 10, it can be formed by plane processing using the warping and bending effect. Therefore, as shown in FIG. 12, a pattern of the heating electrode 41-1 of the heater section 41 is arranged between the temperature sensing electrodes 40-1 so as not to overlap the temperature sensing section 40 on the substrate 10, and cantilevered. The pattern of the temperature sensing part 40 and the heater part 41 is warped and the heater part 41 can be formed inside the temperature sensing part 40. In this way, by providing two pairs of patterns of the temperature sensing part 40 and providing the pattern of the heater part 41 in the gap between them, a sacrificial layer can be dispensed with, and the Pt material layer can be formed once. It becomes simple.

  Next, FIG. 13 is a perspective view showing a configuration of a detection element according to a fifth embodiment of the present invention. The sensing element 500 of the present embodiment shown in the same figure is a flow sensor structure diagram in which a heater portion is arranged inside the temperature sensing section, similarly to the sensing element 400 of the fourth embodiment shown in FIG. It is. In the detection element 5 of the present embodiment, the temperature sensing electrodes 50-1 of the temperature sensing unit 50 are arranged in an annular shape. Similarly to the temperature sensing electrode 50-1 of the temperature sensing unit 50 arranged in an annular shape, the detection lead wire 50-2, the power supply lead wire 51-2 of the heat unit 51, and the electrode pads 50-3 and 51-3 are: Although only half are shown in FIG. 13, they are arranged radially. Further, the temperature sensing electrode 50-1 of the temperature sensing unit 50 and the heating electrode 51-1 of the heater unit 51 are arranged in opposite directions so as to face each other when they are bent. According to the detection element 5 of the present embodiment, the flow is guided to the xy plane, and the heater unit 51 is located at the center of the curved surface surrounded by the temperature sensing unit 50. Therefore, the flow is slightly shifted to the z axis. Is less affected. Therefore, all directions of the flow along the xy plane can be detected. Further, since the temperature sensing part 50 has a skewer shape, there is a rectifying action, and a stable output can be obtained even under turbulent conditions, and a rectifying element is unnecessary.

  Here, the manufacturing process of the sensing element of the fifth embodiment will be described with reference to FIGS. 14 and 15 showing the manufacturing process. 14A and 14A are plan views, and FIG. 15B is a cross-sectional view taken along the line F-F ′ in FIG. As shown in FIG. 14, the temperature sensing electrode 50-1 and the detection lead wire 50-2 of the temperature sensing unit 50, the heating electrode 51-1 and the feeding lead wire 51-2 of the heater unit 51, and the electrode pad 50 are formed on the substrate 10. The conductive material film of −3, 51-3 is patterned. Then, as shown in FIGS. 15A and 15B, the insulating layers in the regions of the temperature sensing electrode 50-1 of the temperature sensing unit 50 and the heating electrode 51-1 of the heater unit 51 on the substrate 10 are removed by etching. Then, the temperature-sensitive part 50 and the heater part 51 are not cantilevered in the lower layer and become a cantilever, so that a curved surface is formed by the warping and bending effect and stands on the substrate 10. Further, only the exposed area of the substrate surface is further etched to form the cavity 52.

  Next, FIG. 16 is a diagram showing the configuration of the heater portion in the detection element according to the sixth embodiment of the present invention. FIG. 17 is a diagram showing the configuration of the temperature sensing unit in the sensing element of the present embodiment. Further, FIG. 18 is a diagram showing the overall configuration of the detection element of the present embodiment. 16 (a) and 17 (a) are plan views, FIG. 16 (b) is a cross-sectional view taken along the line GG ′ of FIG. 16 (a), and FIG. 17 (b) is FIG. FIG. 18A is a cross-sectional view taken along the line HH ′ of FIG. 18A, FIG. 18B is a cross-sectional view, and FIG. 18B is a cross-sectional view taken along the line II ′ of FIG. The sensing element 600 of the present embodiment shown in FIG. 18 combines the substrate on which the heater unit 60 in FIG. 16 is formed with the substrate on which the temperature sensing unit 61 in FIG. It has a structure for flowing fluid. In the prior art, there is an influence due to heat exchange with the substrate wall surface before heat transport from the heater part to the temperature sensing part, but the influence can be reduced because the temperature sensing part exists in a place before reaching the substrate wall surface. The process of combination and the accuracy of combination increase compared to a single substrate, but the fine structure is sandwiched between the substrates, so the structure that stands on the substrate is not exposed, so it is hard to break and easy to handle. It is.

  FIG. 19 is a diagram showing the configuration of the heater section in the detection element according to the seventh embodiment of the present invention. FIG. 20 is a diagram illustrating a configuration of a temperature sensing unit in the detection element of the present embodiment. Further, FIG. 21 is a cross-sectional view showing the entire configuration of the sensing element of the present embodiment. 19 (a) and 20 (a) are plan views, FIG. 19 (b) is a cross-sectional view taken along line JJ ′ of FIG. 19 (a), and FIG. 20 (b) is FIG. It is KK 'sectional view taken on the line of (a). As described above, the detection element 700 according to the present embodiment is only required to have the heater unit 70 inside the temperature sensing unit 71. Therefore, as shown in FIG. 20, the temperature sensing portion 71 is bent and the heater portion 70 can be formed inside the temperature sensing portion 71 as shown in FIG. 21.

  Next, FIG. 22 is a perspective view showing the configuration of the sensing element according to the eighth embodiment of the present invention, and FIG. 23A is a plan view showing the sensing element of the present embodiment. FIG. 23B is a cross-sectional view taken along the line LL ′ of FIG. The sensing element 800 of the present embodiment shown in FIGS. 22 and 23 is disposed on the substrate 10, and a single skewer-shaped resistor 80 is formed in the shape of a curved cantilever, and this resistance The body 80 serves both as a heater part and a temperature sensing part. Further, a small current that does not heat the resistor is applied to the resistor 80 or a small voltage is applied, and a large current is applied or a large voltage is applied to cause the resistor 80 to generate heat. Then, the first resistance value of the resistor 80 when a small current is supplied or a small voltage is applied is detected by a resistance value detection unit (not shown), and the resistor 80 when a large current is supplied or a large voltage is applied. The second resistance value is detected. The first resistance value is subtracted from the detected second resistance value, and the flow rate can be calculated based on this subtraction value.

  FIG. 24 is a perspective view showing the configuration of the sensing element according to the ninth embodiment of the present invention. FIG. 25A is a plan view showing the sensing element of the present embodiment, and FIG. FIG. 25B is a sectional view taken along line MM ′ in FIG. The sensing element 900 of the present embodiment shown in FIGS. 24 and 25 tilts a single resistor 90 serving as both a heater part and a temperature sensing part, similar to the sensing element 8 of the eighth embodiment. The resistor 90 is formed so as to bridge the cavity 91. Since the operation is the same as that of the sensing element 800 of the eighth embodiment, a description thereof will be omitted.

Next, FIG. 26 is a diagram showing the configuration of the sensing element according to the tenth embodiment of the present invention. FIG. 26A is a plan view showing the sensing element of the present embodiment. (B) of FIG. 5 is a cross-sectional view taken along line NN ′ of FIG. In the detection element 1000 of the present embodiment shown in the figure, the heater unit 100 and the temperature sensing unit 101 are each formed in an inclined shape and provided independently, and the heater unit 100 and the temperature sensing unit 101 bridge the cavity 102. Is provided. In this way, the heater unit 100 and the temperature sensing unit 101 are separated from the surface of the substrate 10, and the electrode pads 103 on the surface of the substrate 10, the heater unit 100, and the temperature sensing unit 101 have different height steps. In providing the pattern of the continuous electric wiring 104 and providing the cavity 102 in the region where the heater unit 100 and the temperature sensing unit 101 are formed, the steps are not abrupt but a gentle inclination angle. In the Si anisotropic etching means, if the substrate surface is a (1 0 0) plane, the tilt angle is 54.74 degrees with a Si anisotropic etching solution of an alkaline aqueous solution such as KOH using a partial mask of SiO _2. High-precision inclined shapes such as the (1 1 1) plane are obtained and can be used.

Here, the manufacturing process of the sensing element of the tenth embodiment will be described below with reference to FIG. 27 which is a manufacturing process sectional view. First, as shown in FIG. 3A, an SiO ₂ layer of the lower insulating layer 1002 is formed on the Si substrate 1001. A metal material such as Ni, Cu or Al, or a resin material such as polyimide or epoxy may be used. However, since there is a conductive if a metal material, it is necessary to laminate an insulating film such as SiO ₂ before the step of forming a conductive resistor layer which will be described later. Then, as shown in FIG. 5B, the SiO ₂ layer of the lower insulating layer 1002 is partially etched using the photoresist pattern as a mask. An inclined shape is also formed by utilizing the effect of reducing the etching rate around the mask. Here, the formed convex part including the inclined shape part is removed in a process described later, and is sacrificed to form the structure of the heater part 100 and the temperature sensitive part 101 in FIG. 26C, the electrode pad 103, the electric wiring 104, the heater part 100, and the Pt film of the conductive resistance film 1003 that becomes the temperature sensitive part 101 are laminated. Next, as shown in FIG. 5D, a Pt film pattern of the conductive resistance film 1003 is formed. Then, as shown in FIG. 5E, the SiO ₂ film of the upper protective film 1004 is laminated, but this film may or may not be present. Next, as shown in FIG. 6F, the regions of the heater unit 100 and the temperature sensing unit 101 in FIG. 26 and the SiO ₂ film of the upper protective film 1004 on the electrode surface are removed by etching. Also, as shown in (g) of the figure, the Si substrate in the regions of the heater unit 100 and the temperature sensing unit 101 of FIG. 26 is removed by etching to form the cavity 102 of FIG.

Further, another manufacturing process will be described below with reference to FIG. 28 which is a manufacturing process sectional view. First, as shown in (a) of the figure, a SiO ₂ film of the lower insulating layer 1002 is laminated on the Si substrate 1001, and as shown in (b) of the same figure, the SiO ₂ film of the lower insulating layer 1002 is formed. Partially etch. Then, as shown in FIG. 6C, the Si substrate 1001 is etched leaving the SiO ₂ film region of the lower insulating layer 1002 to form an inclined shape. In this case, the above Si anisotropic etching is used. Then, as shown in FIG. 4D, the SiO ₂ film of the lower insulating layer 1002 is formed on the entire surface. Next, as shown in FIG. 5E, a Pt film of the conductive resistance film 1003 is laminated. Next, as shown in FIG. 5F, a Pt film pattern of the conductive resistance film 1003 is formed. And as shown in (g) of the figure, the SiO ₂ film of the upper protective film 1004 is laminated. Next, as shown in (h) of FIG. 26, the SiO ₂ film of the upper protective film 1004 in the region of the heater unit 100, the temperature sensitive unit 101 and the region of the electrode pad 103 in FIG. Then, as shown in (i) of the figure, the Si substrate 1001 in the regions of the heater unit 100 and the temperature sensing unit 101 in FIG. 26 is removed by etching to form the cavity 102 in FIG.

  Next, FIG. 29 is a perspective view showing a configuration of a vacuum gauge according to an embodiment of another invention. A vacuum gauge 2000 of another invention shown in the figure is a heat conduction type vacuum gauge. For example, the sensing element 400 of the fourth embodiment is enclosed in a vacuum vessel 2001, and wiring from each electrode pad to the outside of the vessel is performed. The heating power is supplied to the heater unit 41 and the amount of heat conducted from the heater unit 41 to the space is captured by the temperature sensing unit 40. The detection output of the temperature sensing unit 40 corresponds to the degree of vacuum in the space. When heat is transferred from the heater unit 41 to the space, it diffuses in three dimensions, so that it is possible to efficiently obtain a high output by being surrounded by the curved temperature sensing unit 40, and there is little influence from the outside of the temperature sensing unit 40. Become.

  FIG. 30 is a perspective view showing a configuration of a vacuum tube according to an embodiment of another invention. The vacuum tube 3000 of another invention shown in the figure is a triode type ionization vacuum tube, and for example, an element having the same configuration as the detection element 400 of the fourth embodiment is enclosed in a vacuum vessel 3001. In the sensing element 400 of the fourth embodiment, the temperature sensing unit 40 is a grid 3002, the heater unit 41 is a filament 3003, and the substrate 10 on the bottom surface of the cavity is a collector 3004. Therefore, when (thermal) electrons are emitted from the filament 3003 to the space, it is three-dimensionally diffused, and therefore, by being surrounded by the curved grid 3002, a high output can be obtained efficiently and the influence from the outside is reduced. The cavity of the substrate to be the collector 3004 has a concave shape corresponding to the filament 3003 and the grid 3002, which is convenient. The (thermal) electrons of the filament 3003 drawn out with the assistance of the grid 3002 are currents flowing between the collector 3004 and the substrate, and correspond to the degree of vacuum.

  The present invention is not limited to the above-described embodiments, and it goes without saying that various modifications and substitutions are possible as long as they are described within the scope of the claims.

It is a perspective view which shows the structure of the detection element which concerns on the 1st Example of this invention. It is a flow velocity measurement characteristic view of air at a distance along the substrate surface from the substrate end surface and a distance away from the substrate surface. It is a manufacturing-process figure of the detection element of the example of 1st Embodiment. It is a manufacturing-process figure of the detection element of the example of 1st Embodiment. It is a manufacturing-process figure of the detection element of the example of 1st Embodiment. It is sectional drawing explaining the method of forming a three-dimensional temperature sensing part. It is a top view which shows the structure of the detection element which concerns on the 2nd Example of this invention. It is a perspective view which shows the structure of the detection element which concerns on the 3rd Embodiment of this invention. It is a top view which shows the manufacturing process of the sensing element of the example of 3rd Embodiment. It is a figure which shows the manufacturing process of the detection element of the example of 3rd Embodiment. It is a perspective view which shows the structure of the detection element which concerns on the 4th Example of this invention. It is a figure which shows the manufacturing process of the detection element of the example of 4th Embodiment. It is a perspective view which shows the structure of the detection element which concerns on the 5th example of embodiment of this invention. It is a top view which shows the structure of the detection element which concerns on the example of 5th Embodiment. It is a figure which shows the manufacturing process of the detection element of the example of 5th Embodiment. It is a figure which shows the structure of the heater part in the detection element which concerns on the 6th Example of this invention. It is a figure which shows the structure of the temperature sensing part in the detection element of the example of 6th Embodiment. It is a figure which shows the whole structure of the detection element of the example of 6th Embodiment. It is a figure which shows the structure of the heater part in the detection element which concerns on the 7th Example of this invention. It is a figure which shows the structure of the temperature sensing part in the detection element of the example of 7th Embodiment. It is sectional drawing which shows the whole structure of the detection element of the example of 7th Embodiment. It is a perspective view which shows the structure of the detection element which concerns on the 8th Embodiment of this invention. It is a figure which shows the structure of the detection element of the example of 8th Embodiment. It is a perspective view which shows the structure of the detection element which concerns on the 9th Embodiment of this invention. It is a figure which shows the structure of the detection element of the example of 9th Embodiment. It is a figure which shows the structure of the detection element which concerns on the 10th Embodiment of this invention. It is manufacturing process sectional drawing which shows another manufacturing process of the detection element of 10th Embodiment. It is manufacturing process sectional drawing which shows another manufacturing process of the detection element of 10th Embodiment. It is a perspective view which shows the structure of the vacuum gauge which concerns on one embodiment of another invention. It is a perspective view which shows the structure of the vacuum tube which concerns on one embodiment of another invention.

Explanation of symbols

10; Substrate, 11; Cavity, 12; Bridge, 13; Heater part,
14, 15; temperature sensing part,
100, 200, 300, 400, 500, 600, 700, 800, 900, 1000; sensing element,
2000; vacuum gauge, 3000; vacuum tube.

Claims (13)

  A substrate having a through hole or a cavity, a heater portion provided so as to be bridged on the through hole or the cavity, having a shape of a warped and cantilever and having a heating electrode standing in the space, and the through hole or the cavity And a temperature sensing part having a temperature sensing electrode which is bent and bent in the shape of a cantilever and rises in the space, and the amount of heat transported from the heater part is measured by the temperature sensing part. Sensing element.   The heater unit and the temperature sensing unit are arranged adjacent to each other, and the amount of heat transported by the fluid from the heater unit according to the flow rate / flow rate of the fluid or the thermal conductivity of the atmosphere is measured by the temperature sensing unit. Sensing element.   The flow velocity is measured by a distance between the heater portion and the temperature sensing portion and a heat transfer time transported by the fluid from the heater portion according to a flow velocity / flow rate of the fluid or a thermal conductivity of the atmosphere. The sensing element according to 1 or 2.   The sensing element according to claim 1, wherein the heating electrode and the temperature-sensitive electrode have a shape along a pipe-shaped curved surface.   The sensing element according to claim 1, wherein the heater section is arranged inside the temperature sensing section along a fluid flow.   The sensing element according to claim 1, wherein the heater section is arranged inside the temperature sensing section along a direction crossing a fluid flow.   The sensing element according to claim 1, wherein the temperature sensing electrodes of the temperature sensing portion are arranged in an annular shape, and the heating electrode of the heater portion is arranged at the center of the annular temperature sensing portion.   The first substrate in which the heater portion is disposed in the cavity region and the second substrate in which the temperature sensing portion is disposed in the cavity region are integrally joined with the cavity regions facing each other. The sensing element according to any one of the above.   A substrate having a through hole or a cavity, and a resistor provided to bridge over the through hole or the cavity, having a warped and bent cantilever shape and having an electrode standing in the space, are provided at the timing of heat generation. A heating current is supplied to the resistor to cause the resistor to generate heat, and a detection current is supplied to the resistor at a detection timing to change the resistance value of the resistor at the time of detection from the resistance value of the resistor at the time of heating. A sensing element that calculates the amount of heat transported based on a subtracted value obtained by subtraction.   A substrate having a through-hole or a cavity and a resistor having an inclined electrode provided so as to be bridged on the through-hole or the cavity are provided, and a heating current is passed through the resistor at a heat generation timing. The resistor is heated, and a detection current is passed through the resistor at detection timing, and transported based on a subtraction value obtained by subtracting the resistance value of the resistor at the time of detection from the resistance value of the resistor at the time of heat generation. A sensing element that calculates the amount of heat.   A substrate having a through-hole or cavity, a first resistor having an inclined electrode provided to bridge over the through-hole or cavity, and provided to bridge over the through-hole or cavity. And a second resistor having an electrode having an inclined shape, and the amount of heat transported from the first resistor is measured by the second resistor, or transported from the second resistor. A sensing element, wherein the amount of heat to be measured is measured by the first resistor.   The detection element according to any one of claims 1 to 12 is enclosed in a vacuum vessel, and wiring is drawn out from each electrode pad of the heater unit and the temperature sensing unit to the outside of the vacuum vessel, so that the heat of gas inside the vacuum vessel A vacuum gauge characterized by converting the pressure dependency of conductivity into a degree of vacuum as a temperature fluctuation obtained from the temperature sensing part. The detection element according to any one of claims 1 to 12 is enclosed in a vacuum vessel, wiring is drawn out from each electrode pad and the substrate of the heater unit and the temperature sensing unit to the outside of the vacuum vessel, and the heater unit is a filament. A vacuum tube characterized in that the temperature sensing part is a grid and the substrate is a collector, and a current flowing between the filament and the collector is measured and converted into a degree of vacuum.

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