JP2005181016A - Heat type sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat type sensor which is reduced in working dispersions, in wiring part due to etching. <P>SOLUTION: The heat-type flow rate sensor 100 is provided with a substrate 10, a membrane 20 as a thin part formed on the substrate 10, and a wiring part 30 including a heater 31 formed on the membrane 20 and by patterning the same material. A dummy wiring part 40 which is not electrically connected with the wiring part 30 is provided, with at least a part of the wiring part non-forming region so that the widths of the wiring non-forming region excepting for the forming region of the wiring part 30 are all substantially equal. By providing the dummy wiring part 40, even in the case that all widths of the wiring part non-forming region cannot be set substantially the same by patterning the wiring part 30 in design, all the widths of the wiring part non-forming region can be set substantially equal. Therefore, wraparound condition of light to resist at the time of exposure becomes constant, and so fabrication scattering of each wiring part 30 by etching is reduced. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a thermal sensor including a substrate, a membrane as a thin portion formed on the substrate, and a wiring portion that includes a heater portion formed on the membrane and is formed by patterning the same material. is there.

  Conventionally, as a thermal sensor including a substrate, a membrane as a thin portion formed on the substrate, and a wiring portion including a heater portion formed on the membrane and patterning the same material, for example, a thermal sensor There is a flow sensor.

  This sensor is configured to detect the flow rate of the fluid using the fact that the heat generated by the heater portion is taken away by the fluid passing near the heater portion. As an example of such a thermal flow sensor, the present applicant has previously disclosed Patent Document 1.

  The thermal flow sensor shown in Patent Document 1 is formed by laminating a resistance film (a wiring part including a heater and a thermometer) on a substrate via an insulating film, and at least a part of the wiring part is etched. The wiring pattern is formed by patterning and connecting a plurality of resistors in parallel.

That is, the wiring portion, which has been a thick portion of the conventional line width, is formed into a wiring shape in which a plurality of resistors are connected in parallel, so that the line width of the thin wiring portion is aligned. Thus, by making the line widths of the respective wiring portions substantially the same, etching variations between the respective wiring portions are made the same, and variations in resistance ratios of the respective wiring portions between different chips are suppressed as much as possible. .
JP 2003-35580 A

  However, the variation in processing of the wiring part due to etching depends not only on the line width of the wiring part but also on the width of the wiring part non-formation region in contact with each wiring part. For example, even if the patterns are designed so that the line widths of the respective wiring portions are substantially the same (that is, a predetermined line width), the width of the wiring portion non-formation region in contact with each wiring portion (for example, the width between the wiring portions) is Unless the patterns are designed so as to be substantially the same, the degree of light sneaking into the resist during exposure differs depending on the width of the wiring portion non-forming region, and therefore the line width of the wiring portion formed by etching will vary. . That is, the line width of the wiring portion varies depending on the width of the adjacent wiring portion non-forming region. In this case, the sensor may not be able to exhibit a desired sensor function (for example, sensor sensitivity). Further, in the case of a configuration in which output correction is performed by a correction circuit, the correction circuit may be complicated.

  In the thermal flow sensor described in Patent Document 1, a heater is formed on a membrane (thin portion) of a substrate in order to detect a fluid with high accuracy, and a wide wiring portion non-formation region is formed around the heater. . In this way, the heater is configured so as not to be thermally affected by other wiring parts (for example, a thermometer). Therefore, if all the widths of the wiring part non-formation regions are made substantially equal by patterning the wiring parts and the processing variation of the wiring parts due to etching is to be reduced, it is necessary to match the wide part of the wiring part non-formation regions. It becomes difficult to reduce the size of the sensor.

  In view of the above problems, an object of the present invention is to provide a thermal sensor in which processing variations of a wiring portion due to etching are reduced.

  In order to achieve the above object, the thermal sensor according to claim 1 includes a substrate, a membrane as a thin portion formed on the substrate, and a heater portion formed on the membrane, and includes the same material. And a wiring portion formed by patterning. On the substrate including the membrane, a dummy that is not electrically connected to the wiring part at least in a part of the wiring part non-formation region so that all the widths of the wiring part non-formation region excluding the wiring part formation region are substantially equal. A wiring portion is provided.

  In this way, by providing a dummy wiring portion that is not electrically connected to the wiring portion in the wiring portion non-forming region, the width of all the wiring portion non-forming regions cannot be set substantially equal on the wiring portion pattern. In addition, it is possible to set all the widths of the wiring portion non-forming regions to be substantially equal. Accordingly, since the degree of light sneaking into the resist during exposure is constant, the processing variation of the wiring portion (line width processing error) due to etching is reduced. That is, the sensor can exhibit a desired sensor function. Even in the case of a configuration in which output correction is performed by the correction circuit, the correction circuit is simplified.

  In addition, the width of the other wiring portion forming region can be matched to the narrowest portion of the wiring portion non-forming region. Therefore, the size of the sensor can be reduced.

  As described in claim 2, the dummy wiring portion is preferably made of the same material as the wiring portion.

  Since the dummy wiring part is not electrically connected to the wiring part, the dummy wiring part may be made of a material different from that of the wiring part. However, by using the same material, the manufacturing cost can be reduced (the manufacturing process can be simplified).

  The dummy wiring portion may be provided between the wiring portions as described in claim 3, and particularly preferably formed on the membrane as described in claim 4.

  For example, in order to improve the sensor sensitivity, the heater part formed on the membrane is usually formed apart from the other wiring part except for the connection part with the other wiring part. That is, there is a wiring part non-formation region that is wider than the width between the other wiring parts between the wiring parts between the heater part and the other wiring parts. Forming other wiring parts excluding the heater part in this wiring part non-formation region is difficult in practical use because sensitivity is lowered. Further, when the width of the other wiring part non-forming region is matched with the width of the wiring part non-forming region (adjacent to the heater part), it is difficult to reduce the size of the sensor.

  However, if the dummy wiring portion is not electrically connected to the wiring portion, the widths of all the wiring portion non-forming regions can be made substantially equal without reducing the sensor sensitivity.

  The formation position of the dummy wiring portion is not limited to the wiring portion non-forming region adjacent to the heater portion, and may be between the wiring portions not adjacent to the heater portion. As a result, processing variations due to etching of all the wiring portions are reduced, so that the sensor can exhibit a desired sensor function.

  Further, when there is a wide wiring part non-formation region between the outer peripheral part of the wiring part and the outer peripheral end of the substrate on the wiring part pattern, the wiring part as described in claim 5 It suffices if the dummy wiring portion is provided closer to the outer peripheral end portion of the substrate than the outer peripheral portion.

  In this case, the width of the wiring part non-formation region on the outer peripheral end side of the substrate with respect to the outer peripheral part of the wiring part can be made substantially equal to the width of the other wiring part non-formation region (that is, between the wiring parts). Variation in processing at the outer peripheral portion of the wiring portion due to etching can also be reduced.

  Further, as the above-described thermal sensor, for example, as described in claim 6, the thermal sensor is disposed in a fluid passage as a measurement target, and detects the flow rate of the fluid based on the amount of heat transmitted from the heater portion to the fluid. There may be.

  The thermal sensor according to any one of claims 1 to 5 is suitable as a thermal flow sensor. However, other than that, it is applicable to a gas sensor or the like.

  In addition, as described in claim 7, in the thermal type flow sensor having a configuration in which the heater unit is a pair, one is arranged on the upstream side with respect to the fluid, and the other is arranged on the lower side with respect to the fluid. The present invention can be applied.

  In the thermal flow sensor with such a configuration, not only the flow rate of the fluid but also the flow direction of the fluid is detected from the difference between the amount of heat taken away from the upstream heater by the fluid and the amount of heat taken away from the downstream heater. For this reason, it is desirable that both heater portions are arranged close to each other, the wiring width is narrow, and resistance value pairing is good (for example, the same resistance value).

  In this case, on the pattern of the wiring part, a wiring part non-formation region having a width wider than that between the other wiring parts exists at least between the heater part and the other wiring part. Therefore, by providing a dummy wiring part in this wiring part non-formation region, processing variations of the wiring part due to etching can be reduced, and the pair property (resistance value) of both heater parts is improved.

  Preferably, the substrate is a semiconductor substrate, and the wiring portion is preferably provided on the substrate via an insulating film.

  By using a semiconductor substrate, a substrate having a membrane can be easily formed by a general semiconductor manufacturing technique. That is, the thermal sensor can be manufactured at low cost.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the present embodiment, a thermal flow sensor is taken as an example of the thermal sensor and will be described below.
(First embodiment)
1A and 1B are diagrams showing a schematic configuration of a thermal flow sensor in the present embodiment, where FIG. 1A is a plan view and FIG. 1B is a cross-sectional view taken along a line AA in FIG. In FIG. 1A, for convenience, the wiring portion and the dummy wiring portion are shown in a transparent manner, and the dummy wiring portion is hatched. Further, in FIG. 1 (a), the white arrow indicates the flow direction of the fluid, and in FIGS. 1 (a) and 1 (b), the fluid flows in the thermal flow sensor on the arrow side from the two-dot chain line. It is set as the site | part arrange | positioned in an intake pipe (not shown).

  As shown in FIGS. 1A and 1B, the thermal flow sensor 100 shown in this embodiment includes a substrate 10, a membrane 20 as a thin portion formed on the substrate 10, and a substrate 10 including the membrane 20. The wiring part 30 formed by patterning the same material on the upper part and the dummy wiring part 40 formed on at least a part of the wiring part non-formation region where the wiring part 30 is not formed on the substrate 10 are provided.

  The substrate 10 is a semiconductor substrate made of single crystal silicon and has an opening 11 corresponding to the position where the membrane 20 is formed as a thin portion. In the present embodiment, the opening 11 is opened with a rectangular region as indicated by a one-dot chain line in FIG. 1A on the lower surface side of the substrate 10, and this opening area goes to the upper surface side of the substrate 10. The area is reduced, and the upper surface of the substrate 10 has a rectangular area as indicated by a broken line in FIG.

  Accordingly, the membrane 20 is formed so as to bridge the upper surface of the opening 11 and is formed thinner than other parts of the thermal flow sensor 100, so that the heat capacity can be kept low. Thermal insulation from this part is ensured. Note that a rectangular region indicated by a broken line in FIG. 1A is equivalent to a region where the membrane 20 is formed.

  A silicon nitride film 12 is formed on the lower surface of the substrate 10 as a mask when the opening 11 is formed. An insulating film 13 (for example, a silicon nitride film) is formed on the upper surface of the substrate 10, and a silicon oxide film 14 is formed on the insulating film 13.

  On the silicon oxide film 14, a wiring portion 30 and a dummy wiring portion 40 are formed by patterning the same polycrystalline silicon film.

  The wiring part 30 is composed of a pair of heater parts 31 provided at the formation site of the membrane 20, a pair of temperature sensing parts 32 for detecting temperature, and a lead part 33 for connecting these to a pad part described later. The

  Although various forms are possible as the wiring part 30, in the present embodiment, the heater part 31 is based on a change in resistance temperature coefficient of the heater part 31 in addition to a function as a heating element that generates heat by supplying current. It senses its own temperature. Then, the flow rate is detected based on the heat generated by the circulating fluid (for example, air) among the heat generated by the upstream heater unit 31a and the downstream heater unit 31b. In addition, the flow direction of the fluid is sensed based on the difference in the amount of heat taken away by the fluid among the heat generated in each of the upstream heater portion 31a and the downstream heater portion 31b.

  Further, the amount of current supplied to the heater unit 31 is controlled based on the temperature difference between the upstream heater unit 31a and the upstream temperature sensor 32a and the temperature difference between the downstream heater unit 31b and the downstream temperature sensor 32b. The

  The dummy wiring part 40 is electrically insulated from the wiring part 30. In the present embodiment, like the wiring part 30, the dummy wiring part 40 is formed by patterning a polycrystalline silicon film. And as shown to Fig.1 (a), it forms in the wiring part non-formation area | region between the heater part 31 and the lead part 33. FIG. Details thereof will be described later.

  A protective film 15 made of, for example, a silicon nitride film is formed on the wiring part 30 and the dummy wiring part 40, and a contact hole 15a is formed in the protective film 15. The contact hole 15a is formed with a pad portion 16 in contact with the end portion of the lead portion 33, and the wiring portion 30 is connected to the pad portion 16 through a bonding wire 17 and is used for an output correction circuit board (FIG. (Not shown) or the like.

  In the thermal flow sensor 100, the region including the connecting portion between the pad portion 16 and the bonding wire 17 and not disposed in the intake pipe is provided with a protective material 18 such as a gel as shown in FIG. Is formed. The thermal flow sensor 100 is fixed to, for example, a mold case (not shown) and attached to the intake pipe. In addition, instead of the protective material 18, it may be configured to be directly protected by a mold case.

  Next, feature points of the present embodiment will be described with reference to FIGS. FIG. 2 is an enlarged plan view of the dummy wiring portion 40 and its peripheral portion in FIG. In FIG. 2, for convenience, the dummy wiring portion 40 is hatched.

  In order for the thermal flow sensor 100 to perform a desired sensor function, it is necessary to process each wiring part 30 so as to have a desired resistance. When each wiring part 30 is formed by etching the same material, the resistance of each wiring part 30 is strongly affected by the processing variation of the line width. This processing variation is the width of the wiring part non-formation region in contact with the wiring part 30. Affected by.

  Specifically, since the degree of light sneaking into the resist during exposure differs depending on the width of the wiring part non-formation region, the pattern design is made so that the width of the wiring part non-formation region in contact with each wiring part 30 is substantially the same. Otherwise, the processing variation of the wiring part 30 formed by etching increases. For example, even if a pair of heater portions 31 (31a, 31b) having the same line width is formed, if the widths of the wiring portion non-forming regions adjacent to the respective heater portions 31 are different, the heater portions formed by etching The line widths of 31 will be different from each other. In other words, the thermal flow sensor 100 may not perform a desired sensor function (for example, sensor sensitivity may be reduced). Further, in the case of a configuration in which output correction is performed by a correction circuit, the correction circuit may be complicated.

  In order to detect the fluid with high accuracy, the thermal flow sensor 100 normally has a wiring portion so that a heater portion 31 is formed on the membrane 20 of the substrate 10 and a wide wiring portion non-forming region exists around the heater portion 31. 30 is designed.

  Further, when detecting the flow direction of the fluid not only from the flow rate of the fluid but also from the difference between the amount of heat taken away from the upstream heater portion 31a by the fluid and the amount of heat taken away from the downstream heater portion 31b, FIG. ), It is desired that the upstream heater portion 31a and the downstream heater portion 31b are arranged close to each other, have a narrow wiring width, and have good resistance value pairing (for example, the same resistance value).

  Therefore, in designing the wiring part 30, it is difficult to make all the widths of the wiring part non-formation regions substantially equal to reduce the processing variation of the wiring part due to etching. Even if the wiring part 30 is designed in accordance with the wide part of the wiring part non-forming region, it is difficult to reduce the size of the thermal flow sensor 100. Therefore, normally, in the thermal flow sensor 100, since the width of the wiring part non-formation region in contact with each wiring part 30 is not uniform, the processing variation of each wiring part 30 due to etching is large.

  However, in the thermal type flow sensor 100 according to the present embodiment, as shown in FIGS. 1A and 2, the upstream heater portion 31 a in which the width of the wiring portion non-forming region is widened due to the design of the wiring portion 30. A dummy wiring portion 40 is formed between the lead portion 33 and between the downstream heater portion 31 b and the lead portion 33. Since the dummy wiring portion 40 is formed, the widths of all the wiring portion non-forming regions are substantially the same. In addition, the arrow in FIG. 2 is all wiring part non-formation area | regions (between the heater parts 31, between the heater part 31 and the lead part 33, between the temperature sensing bodies 32, between the temperature sensing body 32 and the lead part 33, It is shown that the widths between the lead portions 33 and between the outer peripheral portion of the lead portion 33 and the outer peripheral end portion of the substrate 10 are substantially equal.

  Thus, by providing the dummy wiring part 40, the width of all the wiring part non-formation regions can be made substantially equal, and processing variations of the wiring part 30 due to etching can be reduced. Therefore, the thermal flow sensor 100 can exhibit a desired sensor function. Further, even when the sensitivity correction is performed by the correction circuit, the correction circuit is simplified.

  In particular, in the present embodiment, since the processing variation of the heater unit 31 (upstream heater unit 31a and downstream heater unit 31b) that is important for the sensor sensitivity is reduced, the resistance values of the heater units 31a and 31b are reduced. Pairing is also improved, and the flow direction of the fluid can be detected with high accuracy.

  Further, by providing the dummy wiring portion 40, the width of the other wiring portion forming region can be adjusted to the narrowest portion in the wiring portion non-forming region, so that the size of the thermal flow sensor 100 can be reduced. can do.

  Next, an example of the manufacturing method of the thermal flow sensor 100 described above is shown in the plan view shown in FIG. 1 (a) and the steps shown in FIGS. 3 (a) to 3 (c) and FIGS. 4 (a) and 4 (b). It demonstrates using another sectional drawing. 3 (a) to 3 (c) and FIGS. 4 (a) and 4 (b) show the AA cross section of FIG. 1 (a).

  First, as shown in FIG. 3A, an insulating film 13 made of a silicon nitride film is formed on the upper surface side of the substrate 10 made of single crystal silicon by a CVD method. The insulating film 13 serves as an etching stopper when the substrate 10 described later is etched. Note that since the insulating film 13 is an element constituting the membrane 20, it is important to form the insulating film 13 by controlling the film stress. For this reason, it may be formed as a composite film composed of, for example, a silicon nitride film and a silicon oxide film, if necessary.

  Then, a silicon oxide film 14 is formed by a CVD method so as to cover the insulating film 13. This silicon oxide film 14 improves the adhesion of the wiring part 30 made of a polycrystalline silicon film formed immediately above, and serves as an etching stopper when the wiring part 30 is formed by etching.

  Next, a polycrystalline silicon film is formed on the silicon oxide film 14 by a CVD method, and an impurity such as phosphorus is introduced and adjusted so as to obtain a predetermined resistance value. Subsequently, the polycrystalline silicon film is patterned by a photolithography process, and as shown in FIG. 1A and FIG. 3B, a wiring portion 30 including a heater portion 31, a temperature sensitive portion 32, and a lead portion 33; Then, the dummy wiring part 40 is formed.

  Here, the wiring portion 30 is patterned so that all the widths of the wiring portion non-forming regions which are the non-forming regions of the wiring portion 30 are substantially equal. However, when there is a portion where the widths cannot be substantially equal by design (for example, due to sensor sensitivity), the polycrystalline wiring is formed so that a dummy wiring portion 40 that is not electrically connected to the wiring portion 30 is formed in the portion. The silicon film is patterned.

  In the present embodiment, the wiring portion 30 is designed so that all the widths of the wiring portion non-forming regions except for the wiring portion non-forming region between the heater portion 31 and the lead portion 33 are substantially equal in design of the wiring portion 30. Is formed. And since the wiring part non-formation area | region between the heater part 31 and the lead part 33 is wider than another wiring part non-formation area | region, the dummy wiring part 40 is formed. Thereby, the wiring part non-formation region between the heater part 31 and the lead part 33 is reduced, and both between the heater part 31 and the dummy wiring part 40 and between the lead part 33 and the dummy wiring part 40. The width of the wiring part non-forming region is substantially equal to the width of each other wiring part non-forming region. Therefore, the degree of light sneaking into the resist during exposure becomes equal, and the processing variation of each wiring portion 30 during dry etching is reduced.

  The material constituting the wiring portion 30 and the dummy wiring portion 40 is not limited to the polycrystalline silicon film. In addition, a single crystal silicon film or a low resistance metal material (Pt, Al, etc.) may be used. Further, since the dummy wiring portion 40 is not electrically connected to the wiring portion 30, the dummy wiring portion 40 may be made of a material different from the material constituting the wiring portion 30. Although not shown, a silicon oxide film may be formed on the surfaces of the wiring part 30 and the dummy wiring part 40 by thermal oxidation.

  After the formation of the wiring part 30 and the dummy wiring part 40, a protective film 15 is formed as shown in FIG. The protective film 15 may be formed by selecting a material suitable for the usage environment of the thermal flow sensor 100. Since the thermal flow sensor 100 in the present embodiment is disposed, for example, in an intake pipe of an in-vehicle internal combustion engine, in order to ensure environmental resistance (particularly dust resistance), a silicon nitride film is used as the protective film 15 by, for example, a CVD method. Form. The protective film 15 may have other configurations, a silicon oxide film, or a composite film of a silicon oxide film and a silicon nitride film.

  After the protective film 15 is formed, the protective film 15 is subjected to a photolithography process to form a contact hole 15 a at a position corresponding to the end of the lead portion 33. Then, for example, an Al film is formed in a predetermined region including the contact hole 15a and patterned to form a pad portion 16 as an external connection terminal.

  After the formation of the pad portion 16, a silicon nitride film 12 for an etching mask is formed on the entire lower surface of the substrate 10 by, for example, plasma CVD. Then, an opening is formed in a region where the membrane 20 is to be formed by photolithography, and the substrate 10 is etched using, for example, a KOH solution. In this etching, the substrate 10 is etched until the insulating film 13 provided on the upper surface of the substrate is exposed, and a membrane 20 as a thin portion is formed on the substrate 10 as shown in FIG.

  Thereafter, the chip is divided into individual chips by dicing, and as shown in FIG. 4B, bonding processing is performed on the pad section 16 with the bonding wire 17 so that the wiring section 30 is connected to the outside (for example, a circuit board for output correction). Electrically connected. And in order to protect the connection part of the pad part 16 and the bonding wire 17 from corrosion etc., the protective material 18 which consists of a gel etc. so that the predetermined area | region (part arrange | positioned out of an intake pipe) containing the said connection part may be covered. Form. Through the above steps, the thermal flow sensor 100 according to the present embodiment is formed.

  In the manufacturing process, when a hygroscopic film such as a silicon oxide film is formed, heat treatment may be performed as necessary after the film is formed in order to prevent fluctuations in film stress due to moisture absorption.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made.

  In this embodiment, the example which applies a thermal sensor to the thermal flow sensor 100 was shown. However, other than that, it can be applied to various sensors such as a gas sensor and a pressure sensor.

  In the present embodiment, the substrate 10 is a semiconductor substrate made of silicon, and the wiring portion 30 and the dummy wiring portion 40 are formed on the substrate 10 via the insulating film 13 (and the silicon oxide film 14). Indicated. When a semiconductor substrate is used in this way, a membrane can be easily formed on the substrate 10 by a general semiconductor manufacturing technique. That is, the thermal flow sensor 100 can be manufactured at low cost. However, the substrate 10 may be formed of a glass substrate or the like.

  Further, in the present embodiment, an example in which the dummy wiring portion 40 is formed in the wiring portion non-forming region between the heater portion 31 and the lead portion 33 is shown. However, the dummy wiring portion 40 can be formed on the substrate 10 including the membrane 20 as long as it is a wiring portion non-forming region excluding the formation region of the wiring portion 30. In particular, the patterning of the wiring part 30 is formed in a region where the width of the wiring part non-formation region cannot be made substantially equal by design. Therefore, the formation position, shape, and number are not limited.

  For example, when the wiring part 30 is designed, a wide wiring part non-formation region exists between the outer peripheral part of the wiring part 30 (lead part 33) and the end part of the substrate 10, as shown in FIG. Thus, by providing the dummy wiring portion 40 in the region, the widths of all the wiring portion non-forming regions can be made substantially equal. FIG. 5 is an enlarged plan view showing a modification of the present embodiment, and the dummy wiring part 40 is hatched for convenience. In FIG. 5, the dummy wiring part 40 is also formed in the wiring part non-formation region between the heater part 31 and the lead part 33.

  In addition to this, for example, by providing the dummy wiring portion 40 between the temperature sensing bodies 32, the pair of resistance values of the upstream temperature sensing element 32a and the downstream temperature sensing element 32b can be improved.

  Moreover, as shown in FIG. 6, the dummy wiring part 40 formed in the wiring part non-formation area | region between the heater part 31 (31a, 31b) and the lead part 33 may each be comprised from two or more. Moreover, the dummy wiring part 40 may be formed in the wiring part non-formation area | region between the upstream heater part 31a and the downstream heater part 31b. For example, in order to improve the sensor sensitivity, even when it is desired to take a predetermined distance between the upstream heater portion 31a and the downstream heater portion 31b, the wiring portion non-forming region between the heater portions 31a and 31b. By forming the dummy wiring part 40 on the upper side, it is possible to reduce variations in processing of the heater parts 31a and 31b, and to ensure resistance value pairing. FIG. 6 is an enlarged plan view showing a modification of this embodiment, and the dummy wiring portion 40 is hatched for convenience.

It is a figure which shows schematic structure of the thermal type flow sensor in the 1st Embodiment of this invention, (a) is a top view, (b) is sectional drawing in the AA cross section of (a). It is an enlarged plan view including a dummy wiring part for explaining a feature point. (A)-(c) is sectional drawing according to process which shows the outline of the manufacturing method of a thermal type flow sensor. (A), (b) is sectional drawing according to process which shows the outline of the manufacturing method of a thermal type flow sensor following FIG.3 (c). It is an enlarged plan view which shows a modification. It is an enlarged plan view which shows a modification.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Board | substrate 11 ... Opening part 20 ... Membrane 30 ... Wiring part 31 ... Heater part 31a ... Upstream heater part 31b ... Downstream heater part 32 ... Temperature sensing Body 33 ... Lead 40 ... Dummy wiring 100 ... Thermal flow sensor

Claims (8)

A substrate,
A membrane as a thin part formed on the substrate;
A thermal sensor including a heater part formed on the membrane and having a wiring part formed by patterning the same material,
On the substrate including the membrane, at least a part of the wiring part non-forming region is electrically connected to the wiring part so that all the widths of the wiring part non-forming region excluding the wiring part forming region are substantially equal. A thermal sensor characterized in that a dummy wiring portion that is not connected is provided.   The thermal sensor according to claim 1, wherein the dummy wiring part is made of the same material as the wiring part.   The thermal sensor according to claim 1, wherein the dummy wiring portion is provided between the wiring portions.   The thermal sensor according to claim 3, wherein the dummy wiring portion is formed on the membrane.   5. The thermal sensor according to claim 1, wherein the dummy wiring portion is provided closer to an outer peripheral end portion of the substrate than an outer peripheral portion of the wiring portion.   6. The thermal type according to claim 1, wherein the flow rate of the fluid is detected based on an amount of heat that is disposed in a fluid passage as a measurement target and is transmitted from the heater unit to the fluid. Sensor.   The thermal sensor according to claim 6, wherein the heater unit includes a pair, one of which is disposed on the upstream side with respect to the fluid and the other is disposed on the lower side with respect to the fluid.   The thermal sensor according to claim 1, wherein the substrate is a semiconductor substrate, and the wiring portion is provided on the substrate via an insulating film.

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