WO2019215981A1 - Dispositif de capteur de type thermique - Google Patents

Dispositif de capteur de type thermique Download PDF

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Publication number
WO2019215981A1
WO2019215981A1 PCT/JP2019/005500 JP2019005500W WO2019215981A1 WO 2019215981 A1 WO2019215981 A1 WO 2019215981A1 JP 2019005500 W JP2019005500 W JP 2019005500W WO 2019215981 A1 WO2019215981 A1 WO 2019215981A1
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Prior art keywords
insulating film
film
sensor device
region
tensile
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PCT/JP2019/005500
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English (en)
Japanese (ja)
Inventor
中野　洋
佐久間　憲之
松本　昌大
保夫 小野瀬
太田　和宏
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日立オートモティブシステムズ株式会社
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Publication of WO2019215981A1 publication Critical patent/WO2019215981A1/fr

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
    • G01F1/68—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using thermal effects
    • G01F1/684—Structural arrangements; Mounting of elements, e.g. in relation to fluid flow
    • G01F1/688—Structural arrangements; Mounting of elements, e.g. in relation to fluid flow using a particular type of heating, cooling or sensing element
    • G01F1/69—Structural arrangements; Mounting of elements, e.g. in relation to fluid flow using a particular type of heating, cooling or sensing element of resistive type
    • G01F1/692—Thin-film arrangements

Definitions

  • the present invention relates to a thermal sensor device in which a heating element is formed in a thin film portion covering a cavity formed in a substrate.
  • Patent Document 1 describes an airflow sensor that can increase the mechanical strength by increasing the thickness of the lower thin film and the upper thin film that hold the heating element film of the thin film heating portion, and that reduces the overall warpage.
  • This airflow sensor has a thin film heat generating portion having a structure in which a lower thin film, a heater layer, and an upper thin film are laminated so as to bridge a cavity formed in a silicon substrate.
  • the lower thin film and the upper thin film are each configured by combining a compressive stress film and a tensile stress film, and are laminated so that the lower thin film and the upper thin film have a symmetrical structure with the heater layer interposed therebetween.
  • the compressive stress film is composed of a SiO 2 film having good adhesion
  • the tensile stress film is composed of four Si 3 N 4 films having good moisture resistance.
  • the compressive stress film and the tensile stress film cancel the internal stress, so that the internal stress can be relaxed, and the warp moment can be canceled to suppress the entire warp.
  • the airflow sensor disclosed in Patent Document 1 increases the film thickness of the lower thin film and the upper thin film to improve the mechanical strength (see abstract and paragraph 0009).
  • thermo humidity sensor that detects a change in the amount of heat released from a heating element due to humidity
  • a high temperature and high stress environment causes plastic deformation of the heating element.
  • the thermal stress applied to the heating element it is necessary to minimize the difference in thermal expansion between the heating element and the surrounding thin film.
  • the expansion coefficient of the thin film portion on which the heating element is laminated needs to be as close as possible to the metal material.
  • the thin film portion is warped and becomes an irregular thin film portion, and mechanical strength and productivity are impaired.
  • An object of the present invention is to provide a thermal sensor device capable of reducing stress applied to a heating element and suppressing warpage of a thin film portion under a high temperature environment.
  • the thermal sensor device of the present invention comprises: In a thermal sensor device comprising a thin film portion in which a cavity formed in a substrate is covered with an insulating film, and a heating element formed in the thin film portion, The insulating film in the thin film portion is provided with a compressive region having a partially enhanced compressibility, and the heating element is disposed in the compressive region.
  • Example 1 It is a top view which concerns on one Example (Example 1) of the sensor element used for the thermal sensor apparatus of this invention. It is a circuit diagram which shows one Example of the drive circuit (circuit structure) of the thermal type sensor apparatus of this invention. It is sectional drawing which shows notionally the deformation
  • FIG. 4 is a cross-sectional view showing a cross section of IVA-IVA in FIG.
  • FIG. 3 is a diagram in which a thin film portion 4, a detection heater 5, a tensile region A, and a compressive region B are projected on a virtual plane parallel to the substrate surface (insulating film forming surface) of the substrate 2. It is a figure which shows the temperature dependence of the stress in one Example of the sensor element which concerns on this invention.
  • FIG. 4 is a diagram in which a thin film portion 4, a detection heater 5, a tensile region A, a compressive region B, and a buffer region C are projected on a virtual plane parallel to the substrate surface (insulating film forming surface) of the substrate 2. It is sectional drawing which concerns on one Example (Example 4) of the sensor element used for the thermal sensor apparatus of this invention. It is sectional drawing which concerns on one Example (Example 5) of the sensor element used for the thermal sensor apparatus of this invention.
  • a thermal sensor device in which a heating element is formed in a thin film portion having a thickness of several ⁇ m using a semiconductor process is known.
  • a thermal sensor device that measures the flow rate and concentration of gas utilizes the fact that the amount of heat released from a heating element formed in a thin film portion varies depending on the flow and concentration of gas.
  • a catalyst layer is provided in the thin film portion, and a heating element for activating the catalyst layer so as to react with the combustible gas is provided.
  • Such a sensor device is required to maintain a constant detection sensitivity for a change in a physical quantity of gas for a long period of time.
  • the heating element when the heating element is heated to a high temperature of several hundred degrees for a long time, the heating element and the thin film portion are deformed due to thermal stress. If it does so, the resistance value of a heat generating body will change and a deviation will arise in the heating temperature of a heat generating body. As a result, the detection sensitivity with respect to the change in the physical quantity of the gas changes, and an error occurs in the sensor device.
  • the thermal stress applied to the heating element it is necessary to reduce the difference in thermal expansion between the heating element and the surrounding thin film as much as possible.
  • the expansion coefficient of the thin film portion on which the heating element is laminated needs to be as close as possible to the metal material.
  • the thin film portion is warped and becomes an irregular thin film portion, and mechanical strength and productivity are impaired.
  • a heating element is formed in a thin film part covering a cavity formed in a substrate, and the combined stress of the thin film part in which the heating element is arranged is different from the thin film part in the other region.
  • the thin film portions are formed differently. Thereby, the stress applied to the heating element can be reduced and the warpage of the thin film portion can be suppressed.
  • the thermal sensor device according to the present embodiment provides a thermal sensor device that can maintain measurement accuracy for a long period of time or suppress a decrease in measurement accuracy and ensure mechanical reliability and productivity. can do.
  • Example 1 an embodiment as a thermal sensor device to which the present invention is applied will be described.
  • the present invention is applied to a thermal sensor device that measures intake air humidity of an automobile engine as an example of a thermal sensor device.
  • the physical quantity to be detected by the thermal sensor device of this embodiment is a change in gas concentration
  • the present invention can be applied to a thermal sensor device that measures, for example, hydrogen concentration in addition to humidity.
  • the present invention can also be applied to a flow sensor that detects the flow rate of gas, and the types of gases and physical quantities to be detected are not limited to the following examples.
  • the intake humidity that is measured by the thermal sensor device of this embodiment is measured by detecting a change in the thermal conductivity of the gas due to the gas concentration.
  • the change in thermal conductivity is detected from the change in the amount of heat released from the heating element formed in the sensor element. Since the change in the thermal conductivity of the gas due to the gas concentration is minute, it is necessary to heat the heating element to a high temperature of about 500 ° C. In such a sensor device, the effect of the configuration of the present invention is high.
  • FIG. 1 is a plan view according to one embodiment (Example 1) of a sensor element used in the thermal sensor device of the present invention.
  • the sensor element 1 is formed using a semiconductor microfabrication technique or an etching technique using photolithography.
  • a sensor element (thermal sensor element) 1 has a substrate 2 formed of single crystal silicon.
  • the substrate 2 includes a thin film portion 4 formed with a cavity portion 3 formed by covering the cavity portion 3 with an insulating film.
  • the thin film portion 4 is provided with a detection heater 5 and an auxiliary heater 6 as heating elements.
  • the detection heater 5 and the auxiliary heater 6 are formed as a resistance pattern extending along the plane (film surface) of the thin film portion 4 and having a plurality of folded portions.
  • Detecting heater 5 is used for humidity detection.
  • the detection heater 5 is controlled to a constant temperature of about 500 ° C., for example.
  • the amount of heat released from the detection heater 5 changes depending on the humidity of the atmosphere, and the power required to keep the detection heater 5 at 500 ° C. changes. Humidity can be detected by measuring this power change.
  • the material of the detection heater 5 is preferably a material that is stable at a high temperature and has a high resistance temperature coefficient.
  • metal materials such as platinum (Pt), tantalum (Ta), molybdenum (Mo), and tungsten (W) are suitable.
  • the auxiliary heater 6 is laid so as to surround the detection heater 5.
  • the auxiliary heater 6 can be made of the same material as the detection heater 5.
  • the role of the auxiliary heater 6 is to keep the ambient temperature of the detection heater 5 constant so that the heat radiation amount of the detection heater 5 does not depend on the environmental temperature.
  • the temperature of the auxiliary heater 6 is about 300 ° C., and is set lower than the temperature of the detection heater 5.
  • the auxiliary heater 6 is provided around the detection heater 5 so as to surround the detection heater 5, but the auxiliary heater 6 is not essential in order to obtain the effect of the present invention.
  • the auxiliary heater 6 is for compensating the temperature dependence due to the environmental temperature, and the effect of the present invention can be obtained even in a configuration without the auxiliary heater 6.
  • the substrate 2 is provided with electrode pads 7a to 7d for connecting the detection heater 5 and the auxiliary heater 6 to an external drive circuit.
  • Aluminum (Al) or the like is selected for these electrode pads 7a to 7d.
  • FIG. 2 is a circuit diagram showing an embodiment of a drive circuit (circuit configuration) of the thermal sensor device of the present invention.
  • the thermal sensor device 100 is the entire drive circuit including the sensor element 1.
  • the thermal sensor device 100 described in the first embodiment is also applied to other embodiments.
  • the drive circuit includes a detection heater 5 and an auxiliary heater 6, a bridge circuit (first bridge circuit) BC1 that controls heating of the detection heater 5, and a bridge circuit (second bridge circuit) BC2 that controls heating of the auxiliary heater 6. Become.
  • the bridge circuit BC1 including the detection heater 5 has a configuration in which a series circuit in which the resistor 8a is connected to the detection heater 5 and a series circuit in which the resistor 8b and the resistor 8c are connected are connected in parallel.
  • the potential of the connection portion (intermediate portion) between the detection heater 5 and the resistor 8a (first intermediate potential) and the potential of the connection portion (intermediate portion) between the resistors 8b and 8c (second intermediate potential) are a differential amplifier. It is input to 9a.
  • the differential amplifier 9a outputs a voltage or current corresponding to the difference in input voltage (potential difference between the first intermediate potential and the second intermediate potential).
  • the output of the differential amplifier 9a is connected between the detection heater 5 of the bridge circuit BC1 and the resistor 8b, and is fed back as a heating current of the detection heater 5.
  • the bridge circuit BC2 including the auxiliary heater 6 has a configuration in which a series circuit in which the resistor 10a is connected to the auxiliary heater 6 and a series circuit in which the resistor 10b and the resistor 10c are connected are connected in parallel.
  • the potential (third intermediate potential) at the connection portion (intermediate portion) between the auxiliary heater 6 and the resistor 10a and the potential (fourth intermediate potential) at the connection portion (intermediate portion) between the resistors 10b and 10c are the differential amplifier. 9b.
  • the differential amplifier 9b outputs a voltage or current corresponding to the difference in input voltage (potential difference between the third intermediate potential and the fourth intermediate potential).
  • the output of the differential amplifier 9b is connected between the auxiliary heater 6 of the bridge circuit BC2 and the resistor 10b, and is fed back as a heating current of the auxiliary heater 6.
  • the detection heater 5 is made of a metal material, and the surrounding insulating film is made of silicon oxide or silicon nitride. Since the metal material has a large linear expansion coefficient, when heated to a high temperature, expansion is hindered by the surrounding insulating film, and compressive stress acts on the detection heater 5. If the compressive stress is small, the detection heater 5 is elastically deformed even when stress is applied to it. Therefore, the detection heater 5 returns to its original shape when cooled. However, when the thermal stress increases by heating to a high temperature, the detection heater 5 becomes plastically deformed beyond the elastic deformation region, and residual stress accumulates. As a result, the resistance value of the detection heater 5 gradually changes and affects the measurement accuracy.
  • the insulating film is formed by stacking a silicon oxide film having compressive stress and a silicon nitride film having tensile stress. Since the metal material used for the detection heater 5 is compressive, it is desirable that the insulating film be formed of silicon oxide having the same compressive stress as the detection heater.
  • FIG. 3 shows the warp shape when the thin film portion 4 is tensile and compressive.
  • FIG. 3A is a cross-sectional view conceptually showing deformation of a sensor element used in a thermal sensor device, where the film thickness is set so that the composite stress of the laminated film forming the thin film portion becomes tensile. It is a figure which shows the cross-sectional shape of a thin film part.
  • a thin film portion 4 is formed by laminating a silicon oxide film and a silicon nitride film. Each film thickness is set so that the combined stress of the silicon oxide film and the silicon nitride film becomes tensile. In this case, as shown to FIG. 3A, the thin film part 4 becomes a flat shape and can be manufactured favorably.
  • FIG. 3B is a cross-sectional view conceptually showing deformation of the sensor element used in the thermal sensor device, and when the film thickness is set so that the combined stress of the laminated film forming the thin film portion becomes compressive, It is a figure which shows the cross-sectional shape of a thin film part.
  • each film thickness is set so that the combined stress of the silicon oxide film and the silicon nitride film is tensile.
  • the ratio of the silicon oxide film of the thin film portion 4 is increased to make it compressible, the thin film portion 4 is bent and mechanical strength is lowered as shown in FIG. 3B.
  • FIG. 4A is a cross-sectional view showing the IVA-IVA cross section of FIG.
  • a compressible insulating film 11a is formed on the surface of a substrate 2 made of single crystal silicon.
  • the compressible insulating film 11a is mainly made of silicon oxide (SiO 2), and can be formed by a thermal oxide film or CVD (Chemical Vapor Deposition).
  • a tensile insulating film 12a is formed on the compressible insulating film 11a.
  • the tensile insulating film 12a for example, a silicon nitride film (Si3N4) formed by a CVD method can be used.
  • a portion (detection heater forming region corresponding portion) 12a-1 corresponding to the region B where the detection heater 5 is formed is partially removed by etching. That is, the tensile insulating film 12a is formed when the tensile insulating film 12a and the detection heater 5 are projected on the plane (insulating film forming surface) 2a of the substrate 2 or a virtual plane parallel to the plane 2a. The portion 12a-1 that overlaps the region to be removed is removed.
  • a compressible insulating film 11b made of silicon oxide is formed by the same method.
  • the surface of the compressible insulating film 11b is planarized as necessary by CMP (Chemical-mechanical polishing) or the like.
  • the detection heater 5 and the auxiliary heater 6 are formed by forming and patterning a metal film by sputtering or the like.
  • Mo molybdenum
  • platinum, tantalum, tungsten and the like can also be used.
  • a compressive insulating film 11c made of silicon oxide is formed using a plasma CVD method or the like.
  • the portion of the substrate 2 where the detection heater 5 and the auxiliary heater 6 are located is anisotropically etched using potassium hydroxide (KOH) or the like to form the cavity 3.
  • KOH potassium hydroxide
  • the combined stress of the insulating film in the region B where the detection heater 5 is formed needs to be compressible. Therefore, in this embodiment, by partially removing the tensile insulating film 12a, the ratio of the compressive insulating films 11a, 11b, and 11c in the region B where the detection heater 5 is formed is changed to the region of the other thin film portion 4. Increased compared to A. That is, a compressive region B in which the combined stress of the thin film portion 4 formed of the insulating films 11a, 12a, 11b, and 11c is partially compressive is provided, and the detection heater 5 is disposed in the compressive region B. Yes.
  • the region B where the detection heater 5 is formed becomes stronger in compressibility ( ⁇ ), and the other region A of the thin film portion 4 becomes tensile (+ ⁇ ). .
  • the distortion caused by the expansion of the region B where the detection heater 5 is formed can be offset in the surface direction by the region A where the surrounding tensile property is strengthened, and the thin film portion 4 is manufactured in a flat shape. be able to.
  • the tensile insulating film 12a in the region where the detection heater 5 is formed is removed, but the region where the auxiliary heater 6 is formed has a structure in which the tensile insulating film 12a remains.
  • the detection heater 5 has a high temperature and a large thermal stress, but the auxiliary heater 6 has a lower temperature than the detection heater 5 and is less affected by the thermal stress.
  • the removal range can be adjusted as appropriate, for example, by removing the tensile insulating film 11b even in the region where the auxiliary heater 6 is formed.
  • the tensile insulating film 12a in the region B where the detection heater 5 is disposed is completely removed.
  • the tensile insulating film is partially formed below the detection heater 5. It is good also as a structure which left 12a.
  • partially leaving the tensile insulating film 12a means that when two or more tensile insulating films 12a are provided, the detection heater forming region corresponding portion 12a-1 is removed from all the tensile insulating films 12a. It is not necessary, and if the region B is compressible, it means that there may be a layer of the tensile insulating film 12a from which the detection heater forming region corresponding portion 12a-1 is not removed.
  • partially leaving the tensile insulating film 12a means that at least one tensile insulating film 12a composed of one layer or a plurality of layers is configured to be thin.
  • the degree to which the tensile insulating film 12a below the detection heater 5 is removed can be designed according to the required specifications of the system to which the thermal sensor device 100 is applied.
  • the tensile insulating film 12a is formed on the entire surface outside the region B of the detection heater 5, but there is a portion where the tensile insulating film 12a is partially removed outside the region B. Also good. That is, the effect of the present invention can be obtained as long as the tensile strength is high enough to absorb the stress accompanying the compression of the upper and lower insulating films of the detection heater 5.
  • the tensile insulating film 12a to be partially removed is formed so as to be sandwiched between the compressive insulating films 11a, 11b, and 11c.
  • the reason for this is that, by adopting a configuration in which a partially removed film is interposed in a layer close to the intermediate layer in the thin film portion 4, the change in the warping moment due to the planar position of the thin film portion 4 is reduced, and the flatness without unevenness is reduced. This is because the thin film portion 4 can be formed.
  • the tensile insulating film 12a is formed on the lower layer side of the heating elements such as the detection heater 5 and the auxiliary heater 6, but the tensile insulating film 12a is formed on the upper layer side of these heating elements.
  • a structure in which the tensile insulating film 12a in the region where the heating element is formed is partially removed may be employed. In this case, a silicon nitride film using a plasma CVD method or the like can be used.
  • a silicon nitride film is used as the material of the tensile insulating film 12a forming the thin film portion 4.
  • the material is not limited to the silicon nitride film, and the same configuration is possible as long as the material has tensile stress. Can be.
  • aluminum nitride or the like can be used as a material for the tensile insulating film 12a.
  • the internal stress of the thin film portion 4 formed by the laminated film of the silicon nitride film and the silicon oxide film varies depending on the temperature.
  • FIG. 4B is a diagram in which the thin film portion 4, the detection heater 5, the tensile region A, and the compressive region B are projected on a virtual plane parallel to the substrate surface (insulating film forming surface) of the substrate 2.
  • the tensile insulating film 12a in the region B where the detection heater 5 is located is removed in a square shape.
  • the shape to be removed is a polygon or a circle, thereby reducing the stress concentration at the corner and suppressing the strength reduction of the thin film portion 4. it can.
  • FIG. 5 is a diagram showing the temperature dependence of stress in one embodiment of the sensor element according to the present invention.
  • FIG. 5 shows the relationship between the temperature of the thin film portion 4 formed on the single crystal silicon substrate 2 and the internal stress.
  • the thin film portion 4 formed on the substrate 2 made of single crystal silicon has a characteristic that the tensile stress (+ ⁇ ) increases as the temperature increases, and the compressive stress ( ⁇ ) increases as the temperature decreases. .
  • the thin film portion 4 is flat if it is in a high temperature range where tensile stress is applied. However, when the temperature is lowered, the compressibility becomes strong and the thin film portion 4 is warped.
  • the broken line A shown in FIG. 5 is the temperature characteristic of the internal stress of the thin film structure with enhanced tensile properties on the low temperature side (room temperature), and corresponds to the thin film structure in the region A in this embodiment shown in FIG. In the case of the thin film structure in the region A, the tensile property is maintained on the low temperature side and the high temperature side.
  • the solid line B is the temperature characteristic of the internal stress of the thin film structure with enhanced compressibility, and corresponds to the thin film structure of the region B in this embodiment shown in FIG. In the case of the thin film structure in the region B, it becomes tensile on the high temperature side and compressible on the low temperature side (room temperature).
  • the thin film portion 4 of this embodiment has a configuration in which the insulating films having the characteristics of the broken line A and the solid line B are combined.
  • FIG. 6 is a cross-sectional view according to one embodiment (Example 2) of a sensor element used in the thermal sensor device of the present invention.
  • the same components as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.
  • the sensor element 20 of the present embodiment will be described below.
  • Compressive insulating film 21a is formed on the surface of substrate 2 made of single crystal silicon.
  • the compressible insulating film 21a is mainly made of silicon oxide (SiO2), and can be formed by a thermal oxide film or CVD (Chemical Vapor Deposition).
  • a tensile insulating film 22a is formed on the compressible insulating film 21a.
  • the tensile insulating film 22a for example, a silicon nitride film (Si3N4) formed by a CVD method can be used.
  • the tensile insulating film 22a is formed with a uniform film thickness so as to completely cover the cavity 3.
  • a compressible insulating film 21b made of silicon oxide is formed on the tensile insulating film 22a in the same manner.
  • a tensile insulating film 22b made of silicon nitride is formed on the compressible insulating film 21b.
  • the portion corresponding to the region B where the detection heater 5 is formed (detection heater formation region corresponding portion) 12a-1 is partially removed by etching.
  • a compressible insulating film 21c made of silicon oxide is formed by the same method.
  • the surface of the compressible insulating film 21c is planarized as necessary by CMP (Chemical mechanical polishing) or the like.
  • the detection heater 5 and the auxiliary heater 6 are formed by forming and patterning a metal film by sputtering or the like.
  • Mo molybdenum
  • a compressive insulating film 21d made of silicon oxide is formed using a plasma CVD method or the like.
  • a tensile insulating film 22c is formed on the compressible insulating film 21d.
  • silicon nitride formed by a plasma CVD method can be used as the tensile insulating film 22c.
  • the compressible insulating film 21e is formed by the same method.
  • the cavity 3 is formed in the substrate 2 on which the detection heater 5 and the auxiliary heater 6 are located by anisotropic etching using potassium hydroxide (KOH) or the like.
  • the compressible insulating film 21b, the tensile insulating film 22b, the compressible insulating film 21c, and the compressible insulating film 21d of the present embodiment are the same as the compressive insulating film 11a, the tensile insulating film 12a, and the compressible insulating film 11b of the first embodiment. And the compressive insulating film 11c. Further, in this embodiment, since the tensile insulating film 22a and the tensile insulating film 22c are added, the lowermost compressive insulating film 21a and the uppermost compressive insulating film 21e are added.
  • the tensile insulating film 12b is partially removed, so that the region B where the detection heater 5 is formed has a configuration in which the compressibility is enhanced as compared with the other regions A. That is, also in this embodiment, the ratio of the compressible insulating film (silicon oxide film) in the region B where the detection heater 5 is formed is increased as compared with the other part A.
  • the region B where the detection heater 5 is formed has a higher compressibility ( ⁇ ), and the other region A of the thin film portion 4 has a higher tensile property (+ ⁇ ). It has been.
  • a compressible region (compressible thin film portion) B and a tensile region (tensile thin film portion) A are formed in the thin film portion 4 provided in the cavity portion 3, and the compressive region (compressible thin film portion).
  • a detection heater 5 is arranged at B.
  • the tensile insulating film 22a and the tensile insulating film 22c that completely cover the region on the cavity 3 are provided. Further, the detection heater 5 is configured to be interposed between the upper tensile insulating film 22c and the lower tensile insulating film 22a. Since the tensile insulating films 22a and 22c are formed of silicon nitride, the tensile insulating films 22a and 22c have an effect of blocking moisture and oxygen entering from the outside, thereby enhancing the effect of protecting the detection heater 5 from oxidation and corrosion.
  • the structures relating to the tensile insulating films 22a and 22c and the compressible insulating film 21a and the compressible insulating film 21e added to provide the tensile insulating films 22a and 22c are different from the first embodiment.
  • Other configurations can be configured in the same manner as in the first embodiment.
  • the silicon nitride film is formed by partially removing the tensile insulating film 22b located in the intermediate layer. In this case, since the film close to the center in the stacking direction of the thin film portion 4 is partially removed, the change in the warping moment at the planar position of the thin film portion 4 is reduced, and a flat thin film without unevenness is formed. be able to.
  • FIG. 7A is a cross-sectional view according to one embodiment (third embodiment) of a sensor element used in the thermal sensor device of the present invention.
  • a configuration is further added to the second embodiment, and the configuration and effects different from the second embodiment will be described.
  • Components similar to those in the first and second embodiments are denoted by the same reference numerals as those in the first and second embodiments, and the description thereof is omitted.
  • the auxiliary heater 6 is not an essential configuration, the description is omitted in FIG. 7, but the auxiliary heater 6 may be provided as in the first and second embodiments.
  • the sensor element 30 of the present embodiment will be described below.
  • the tensile insulating film 22b is partially removed in the region of the detection heater 5.
  • a buffer region C is provided between the region B where the tensile insulating film 22b of the thin film portion 4 is removed and the region A where the tensile insulating film 22b is formed.
  • the buffer region C relaxes a rapid film quality change at the boundary between the region A and the region B, and has a structure in which the tensile insulating film 22b is gradually removed as the detection heater 5 is approached.
  • the buffer region C can be formed by providing slits or holes in the tensile insulating film 12b. For example, a rapid change in film quality is alleviated by changing the width of the slit, the diameter or width of the hole, or changing the interval between the slit and the hole.
  • an external force may act on the thin film portion 4 of the sensor element 30 due to pressure fluctuation or particle impact.
  • stress is generated in the insulating film.
  • the location where the film quality changes on the thin film portion 4 is likely to break due to stress concentration due to bending.
  • the stress concentration can be relaxed and the strength reduction of the thin film portion 4 can be suppressed.
  • FIG. 7B is a diagram in which the thin film portion 4, the detection heater 5, the tensile region A, the compressive region B, and the buffer region C are projected on a virtual plane parallel to the substrate surface (insulating film forming surface) of the substrate 2.
  • the shape of the slit or hole constituting the buffer region C a shape as shown in FIG. 7B can be considered.
  • the shape of the slit or hole may be other than the shape shown in FIG. 7B.
  • the stress concentration at the boundary between the region A and the region B can be reduced by providing the buffer region C from which the tensile insulating film is removed by a slit or a hole at the boundary between the region A and the region B.
  • the shape of the buffer region C shown in FIG. 7B can be applied to the embodiments described later within a consistent range.
  • the effect of relaxing the stress concentration is improved.
  • FIG. 8 is a cross-sectional view according to an embodiment (embodiment 4) of a sensor element used in the thermal sensor device of the present invention.
  • the present embodiment is a modification of the second embodiment, and the configuration and effect different from the second embodiment will be described.
  • the same configurations as those in the first to third embodiments are denoted by the same reference numerals as those in the first to third embodiments, and the description thereof is omitted.
  • the auxiliary heater 6 is not an essential configuration, the description thereof is omitted in FIG. 8, but the auxiliary heater 6 may be provided as in the first and second embodiments.
  • the sensor element 40 of the present embodiment will be described below.
  • This embodiment is effective when the detection heater 5 has a relatively large pattern.
  • a part of the tensile insulating film 22b is left in the region B where the detection heater 5 of the thin film portion 4 is formed. That is, in this embodiment, the structure of the tensile insulating film 22b is partially different from that of the second embodiment. If the formation area of the detection heater 5 is widened, the area to be compressible is also widened. As a result, the area A around the detection heater 5 becomes narrow, and the compressive strain in the area B of the detection heater 5 cannot be sufficiently absorbed.
  • the tensile insulating film 12b is provided in the region B of the detection heater 5 except for the portion immediately below where the detection heater 5 is patterned.
  • the tensile insulating film 12b just under the patterning of the detection heater 5 is removed. That is, the detection heater 5 and the tensile insulating film 12b do not overlap when the thin film portion 4 is viewed from above. That is, when the detection heater 5 and the tensile insulating film 12b are projected on a plan view similar to FIG. 1, the tensile insulating film 12b made of silicon nitride is provided between the metal patterns constituting the detection heater 5. It has been.
  • FIG. 9 is a cross-sectional view according to one embodiment (Example 5) of the sensor element used in the thermal sensor device of the present invention.
  • the compressibility of the region B in which the detection heater 5 is formed is enhanced as compared with other regions A by forming the oxide film serving as a compressible insulating film into a pressure film.
  • the same configurations as those of the first to fourth embodiments are denoted by the same reference numerals as those of the first to fourth embodiments, and the description thereof is omitted.
  • the auxiliary heater 6 is not an essential configuration, the description is omitted in FIG. 9, but the auxiliary heater 6 may be provided in the same manner as in the first and second embodiments.
  • the sensor element 50 of the present embodiment will be described below.
  • a compressible insulating film 51a is formed on the surface of the substrate 2 made of single crystal silicon.
  • the compressible insulating film 51a is mainly made of silicon oxide and can be formed by a thermal oxide film or CVD (Chemical Vapor Deposition).
  • a tensile insulating film 52a is formed on the compressible insulating film 51a.
  • the tensile insulating film 52a for example, a silicon nitride film formed by a CVD method can be used.
  • the tensile insulating film 52a is formed with a uniform film thickness so as to completely cover the cavity 3.
  • a compressive insulating film 51b made of silicon oxide is formed on the tensile insulating film 52a in the same manner.
  • a detection heater 5 and an auxiliary heater 6 are formed by forming a metal film by sputtering or the like and patterning it.
  • a compressive insulating film 51c made of silicon oxide is formed using a plasma CVD method or the like. The compressible insulating film 51c is removed leaving the region where the detection heater 5 is formed.
  • a tensile insulating film 52b is formed.
  • silicon nitride formed by a plasma CVD method can be used.
  • a compressive insulating film 51d made of silicon oxide is formed by the same method.
  • the compressive insulating film (silicon oxide) in the region B where the detection heater 5 is formed is thicker than other regions. That is, a compressive region B in which the combined stress of the thin film portion 4 formed of an insulating film is partially compressible compared to other regions A is provided, and the detection heater 5 is disposed in the compressive region B. Yes. As a result, the region B where the detection heater 5 is formed can be made more compressible than the other regions A, and the other regions A can be made more tensile.
  • the thickness of the entire insulating film forming the thin film portion 4 is different between the region A where the compressive insulating film is formed thick and the region B where the compressive insulating film is formed thin. Therefore, a protrusion (thick film portion) 53 is formed on the surface of the thin film portion 4.
  • the step 53a of the protrusion (thick film portion) 53 is likely to cause stress concentration due to external force as described above. Therefore, it is desirable to reduce the stress concentration by forming the stepped portion 53a so as to have a step whose height changes gently. Specifically, the stepped portion can be relaxed and the film thickness can be changed gently by known methods such as SOG (Spinson Glass), etch back, and CMP.
  • the configuration in which the compressive insulating film 51c in the other region A is removed while leaving the compressible insulating film 51c in the upper layer (region B) of the detection heater 5 has been described.
  • a similar structure can be formed using the insulating film 51b. That is, if the compressive insulating film 51b is formed thicker than the other regions A in the region B where the detection heater 5 is formed, the effect of the present invention can be obtained.
  • the compressive insulating film 51c or the compressive insulating film 51b is not completely removed in the region A, but the film thickness of the compressible insulating film 51c or the compressive insulating film 51b in the region B.
  • the compressive insulating film 51c or the compressive insulating film 51b in the region A is thinned, the effect of the present invention may be obtained.
  • the following thermal sensor device is obtained.
  • the hollow portion 3 formed in the substrate 2 is formed in the thin film portion 4 covered with the insulating films 11a to 11d, 12a to 12c, 21a to 21e, 22a to 22c, 51a to 51d, 52a and 52b, and the thin film portion 4.
  • the thermal sensor device including the heating element 5 the insulating film in the thin film portion 4 is provided with a compressible region B having a partially enhanced compressibility, and the heating element 5 is disposed in the compressive region B.
  • a tensile region A is formed in the insulating film around the compressive region B.
  • the portions of the insulating film covering the cavity 3 are compressed stress films 11a to 11d, 21a to 21e, and 51a to 51d that are compressible with respect to the substrate 2 at room temperature, and the substrate. 2, tensile stress films 12a to 12c, 22a to 22c, 52a, and 52b that are tensile with respect to 2 are partially removed in the compressive region B.
  • the insulating film includes the lower layer side tensile stress film 22a formed on the lower layer side of the heating element 5 and the upper layer side tensile stress film 22c formed on the upper layer side of the heating element 5.
  • the intermediate tensile stress film 22b is formed thicker than the upper tensile stress film 22c and the lower tensile stress film 22a.
  • the portion of the insulating film includes a region C in which the tensile stress film 22b is removed in a slit shape.
  • the tensile stress film 12a is removed in the compressive region B into a polygon or a circle.
  • the compressive stress films 11a to 11d, 21a to 21e, 51a to 51d are insulating films mainly composed of silicon oxide, and the tensile stress films are silicon nitrides 12a to 12c, 22a to 22c, 52a, 52b. It is an insulating film mainly composed of (9)
  • the heating element 5 is a metal material.
  • this invention is not limited to each above-mentioned Example, Various modifications are included.
  • the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations.
  • a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment.

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  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • General Physics & Mathematics (AREA)
  • Measuring Volume Flow (AREA)

Abstract

La présente invention a pour objet de fournir un dispositif de capteur de type thermique grâce auquel une contrainte appliquée à un élément chauffant peut être réduite et le gauchissement d'une partie de film mince peut être supprimé dans un environnement à haute température. Un dispositif de capteur de type thermique comprend une partie de film mince (4) dans laquelle une partie de cavité (3) formée dans un substrat (2) est recouverte d'un film isolant, et un élément chauffant (5) formé sur la partie de film mince (4), une région compressible (B) dans laquelle la compressibilité est partiellement augmentée dans les films isolants (11a, 12a, 11b, 11c) dans la partie de film mince (4) étant prévue, et l'élément chauffant (5) étant disposé dans la région compressible (B).
PCT/JP2019/005500 2018-05-08 2019-02-15 Dispositif de capteur de type thermique WO2019215981A1 (fr)

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JP2018-089880 2018-05-08
JP2018089880A JP2019196936A (ja) 2018-05-08 2018-05-08 熱式センサ装置

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2000002571A (ja) * 1998-06-16 2000-01-07 Tokyo Gas Co Ltd 熱線式マイクロヒータ
US20070231942A1 (en) * 2001-01-10 2007-10-04 Vanha Ralph S Micromechanical flow sensor with tensile coating
EP2348292A1 (fr) * 2010-01-13 2011-07-27 Sensirion AG Dispositif capteur

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2000002571A (ja) * 1998-06-16 2000-01-07 Tokyo Gas Co Ltd 熱線式マイクロヒータ
US20070231942A1 (en) * 2001-01-10 2007-10-04 Vanha Ralph S Micromechanical flow sensor with tensile coating
EP2348292A1 (fr) * 2010-01-13 2011-07-27 Sensirion AG Dispositif capteur

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