WO2015162853A1 - Physical quantity sensor and physical quantity sensor manufacturing method - Google Patents

Abstract

This physical quantity sensor has: a first substrate (2), which is provided with a supporting substrate (20) having a first end (2a), a second end (2b), a first surface (21), and a second surface (22), and which has a thin section (22a); a second substrate (3), which has a third surface (31) and a second recessed section (31a), said third surface (31) being bonded to the first substrate (2), while being in contact with the first surface (21) of the first substrate (2); and sensing sections (7, 9, 7A, 7B), which detect a physical quantity of a subject to be detected, and which output the physical quantity as electric signals. This physical quantity sensor manufacturing method has: a step for preparing a first wafer (200) having a plurality of the thin sections (22a); a step for preparing a second wafer (300) having a plurality of the second recessed sections (31a) formed in a sixth surface (301); and a step for bonding the first wafer (200) and the second wafer (300) to each other.

Description

Physical quantity sensor and method of manufacturing physical quantity sensor Cross-reference of related applications

This application is based on Japanese Patent Application No. 2014-90264 filed on April 24, 2014 and Japanese Patent Application No. 2014-245251 filed on December 3, 2014, and here The description is incorporated by reference.

The present disclosure relates to a physical quantity sensor and a method for manufacturing the physical quantity sensor.

Conventionally, a sensor chip having a sensing portion is bonded to a resin member, and a thin portion is formed on one surface of the sensor chip by forming a recess on the other surface opposite to the one surface. A physical quantity sensor that detects a physical quantity of a detection body is used.

As one of such sensors, a flow rate sensor that detects the flow rate of a fluid is conventionally known. As this type of flow sensor, one described in Patent Document 1 has been proposed. This flow sensor has a sensing unit for detecting a flow rate of a fluid that is a detection target, and a sensor chip including the sensing unit is bonded to a resin member. On one surface of the sensor chip, a thin portion is formed which is thinned by forming a recess on the other surface opposite to the one surface. In this flow sensor, the flow rate of the fluid flowing above the thin portion is detected by a sensing portion formed on the thin portion of one surface of the sensor chip. Specifically, in this flow sensor, when a fluid passes above the thin wall portion, a change occurs in the temperature distribution detected by the sensing unit, and a resistance value change due to the temperature difference of the detected temperature of the sensing unit caused thereby is detected as an electric signal. As a result, the flow rate of the fluid is detected.

Here, in this flow sensor, in order to prevent a decrease in detection accuracy due to fluid flowing into the recess of the sensor chip, the recess of the sensor chip is covered with the resin member. However, when the resin member is configured to come into contact with the entire other surface of the sensor chip (particularly the peripheral portion of the thin portion), the linear expansion coefficient of the adhesive that fixes the resin, the sensor chip, and the sensor chip to the resin is reduced. Due to the difference, distortion occurs when the temperature of the surrounding environment changes, and the stress generated in the sensor chip increases. In this case, eventually, the stress applied to the thin portion formed on the sensor chip increases. And if stress is applied to the thin part formed in the sensor chip and the thin part is deformed, the sensor characteristics of the flow sensor may change, and the detection accuracy of the flow sensor may be reduced.

Therefore, in this flow sensor, a portion around the thin portion of the sensor chip, that is, a portion around the concave portion and the resin member are configured to have a gap, and the sensor chip is a portion around the concave portion. It is set as the structure supported by the resin member in parts other than. That is, the sensor chip is configured to be supported by the resin member in a portion of the sensor chip that is farther from the peripheral portion of the recess as viewed from the thin portion. Thus, in this flow sensor, the sensor chip is configured to be fixed to the resin member at a portion far from the thin portion of the sensor chip, and thus occurs in relation to the resin member with respect to the thin portion of the sensor chip. There is a risk that it is difficult to apply stress.

The inventors of the present application found the following regarding the physical quantity sensor.

In the flow sensor described in Patent Document 1, a gap is formed between the resin chip and the peripheral portion of the recess in the sensor chip, and the sensor chip has a resin portion other than the peripheral portion of the recess. It is the structure supported by the member. For this reason, in this flow sensor, the contact area between the resin chip and the portion around the recess in the sensor chip is small, and it is difficult for stress to be applied to the thin portion. Here, when the fluid enters the gap, if the gap is wide, the fluid flowing through the gap tends to be turbulent, and a vortex is likely to occur when the fluid wraps into the recess. And if a vortex arises in a recessed part, the temperature distribution which the sensing part formed in the thin part will change, and there exists a possibility that the detection accuracy of a flow sensor may fall by extension. Therefore, in this flow sensor, it is preferable that the gap be narrow so that the intruded fluid is likely to become a laminar flow that is difficult to reduce the detection accuracy of the flow sensor. However, it is not easy to attach the sensor chip to the resin member with high accuracy while narrowing the gap. Also, the time until the adhesive that bonds the resin member and the sensor chip is cured, the resin member and the sensor chip. Must maintain the positional relationship. Thus, there is a possibility that the flow sensor is difficult to manufacture.

Also, physical defects other than the flow rate sensor, such as a pressure sensor that detects the pressure of the detection object and a temperature sensor that detects the temperature of the detection object, have the same drawbacks due to the same circumstances. That is, in a pressure sensor, a temperature sensor, etc., when the gap between the sensor chip and the resin member is formed as described above, if the gap is wide, Foreign matter (metal scrap, organic matter, etc.) may enter and eventually adhere to the sensing unit, causing problems such as a reduction in detection accuracy. For this reason, it is preferable that the gap be narrow in the pressure sensor, the temperature sensor, etc., but in order to narrow the gap, the positional relationship between the resin member and the sensor chip must be maintained, which is difficult to manufacture. There is a risk.

Further, as described above, the flow sensor described in Patent Document 1 is manufactured by cutting a wafer and attaching a resin member to a sensor chip that is made into a unit. That is, in the production of the flow sensor, it is necessary to process the sensor chip separately in a separate manufacturing process such as a process of manufacturing the sensor chip and a process of bonding the resin member to the sensor chip, which may complicate the manufacturing process. is there.

Japanese Published Patent Publication No. 2010-160092

In view of the above points, the present disclosure has a thin portion that is thinned by forming a recess, and a physical quantity sensor in which a sensing portion is formed on the surface of the thin portion, it is difficult to apply stress to the thin portion, An object is to provide an easy configuration.

According to the physical quantity sensor according to one aspect of the present disclosure, the physical quantity sensor has the first end and the second end opposite to the first end, and the first surface and the second surface opposite to the first surface. A first substrate having a thin portion with a first recess on the first surface on the first end side of the support substrate, a third surface, and a direction normal to the second surface As seen, the second substrate includes a second concave portion included in the third surface including the thin portion, and the third surface is bonded to the first substrate while being in contact with the first surface of the first substrate; And a sensing unit that is provided on the second surface of the thin-walled portion and detects a physical quantity of the detected object and outputs it as an electrical signal.

According to the physical quantity sensor manufacturing method according to an aspect of the present disclosure, the physical quantity sensor manufacturing method includes the fourth surface and the fourth surface as members constituting the first substrate of the plurality of physical quantity sensors. A first wafer having a plurality of thin portions is prepared by forming a plurality of first recesses corresponding to each of the plurality of physical quantity sensors on the fourth surface, and having a fifth surface opposite to the surface. And a plate having a sixth surface as a member constituting the second substrate of the plurality of physical quantity sensors, and a plurality of second recesses corresponding to each of the plurality of physical quantity sensors are formed on the sixth surface. After preparing two wafers and preparing the first wafer and the second wafer, each of the plurality of second recesses corresponds to the first corresponding to the plurality of first recesses when viewed from the direction of the normal to the sixth surface. So as to include a recess inward. Has a attaching the first wafer and the second wafer while contacting the surface to the fourth surface, the.

According to the physical quantity sensor and the manufacturing method of the physical quantity sensor according to the present disclosure, a gap is formed between the portion around the thin portion of the first substrate and the second substrate, and the periphery of the thin portion is arranged. The portion other than the portion is fixed by the second substrate. Therefore, compared with the case where the thin portion is fixed at the peripheral portion, it is difficult to apply stress generated in relation to the second substrate to the thin portion. Thereby, the fall of the detection accuracy of the physical quantity sensor by stress being applied to the thin part and the thin part being deformed can be suppressed.

The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description with reference to the accompanying drawings. In the attached drawings
FIG. 1 is a diagram illustrating a planar configuration of a flow sensor according to the first embodiment. FIG. 2 is a cross-sectional view taken along the line II-II of the flow sensor shown in FIG. FIG. 3A is a diagram showing a cross-sectional configuration of a workpiece during the manufacturing process of the flow sensor shown in FIG. FIG. 3B is a diagram showing a cross-sectional configuration of the workpiece during the manufacturing process of the flow sensor shown in FIG. FIG. 3C is a diagram showing a cross-sectional configuration of the workpiece during the manufacturing process of the flow sensor shown in FIG. FIG. 3D is a diagram showing a cross-sectional configuration of a workpiece during the manufacturing process of the flow sensor shown in FIG. FIG. 3E is a diagram showing a cross-sectional configuration of a workpiece during the manufacturing process of the flow sensor shown in FIG. FIG. 3F is a diagram showing a cross-sectional configuration of a workpiece during the manufacturing process of the flow sensor shown in FIG. FIG. 3G is a diagram showing a cross-sectional configuration of the workpiece during the manufacturing process of the flow sensor shown in FIG. FIG. 3H is a diagram showing a cross-sectional configuration of a workpiece during the manufacturing process of the flow sensor shown in FIG. FIG. 3I is a diagram showing a cross-sectional configuration of a workpiece during the manufacturing process of the flow sensor shown in FIG. FIG. 3J is a diagram showing a cross-sectional configuration of the workpiece during the manufacturing process of the flow sensor shown in FIG. FIG. 3K is a diagram showing a cross-sectional configuration of a workpiece during the manufacturing process of the flow sensor shown in FIG. FIG. 4 is a diagram illustrating a planar configuration of the flow sensor according to the second embodiment, FIG. 5 is a diagram showing a VV cross-sectional configuration of the flow sensor shown in FIG. FIG. 6A is a diagram showing a cross-sectional configuration of a workpiece during the manufacturing process of the flow sensor shown in FIG. FIG. 6B is a diagram showing a cross-sectional configuration of the workpiece during the manufacturing process of the flow sensor shown in FIG. FIG. 6C is a diagram showing a cross-sectional configuration of the workpiece during the manufacturing process of the flow sensor shown in FIG. FIG. 6D is a diagram showing a cross-sectional configuration of a workpiece during the manufacturing process of the flow sensor shown in FIG. FIG. 6E is a diagram showing a cross-sectional configuration of the workpiece during the manufacturing process of the flow sensor shown in FIG. FIG. 6F is a diagram showing a cross-sectional configuration of a workpiece during the manufacturing process of the flow sensor shown in FIG. FIG. 6G is a diagram showing a cross-sectional configuration of the workpiece during the manufacturing process of the flow sensor shown in FIG. FIG. 6H is a diagram showing a cross-sectional configuration of a workpiece during the manufacturing process of the flow sensor shown in FIG. FIG. 6I is a diagram showing a cross-sectional configuration of a workpiece during the manufacturing process of the flow sensor shown in FIG. FIG. 6J is a diagram showing a cross-sectional configuration of the workpiece during the manufacturing process of the flow sensor shown in FIG. FIG. 7 is a diagram illustrating a planar configuration of the flow sensor according to the third embodiment, FIG. 8 is a diagram showing a VIII-VIII cross-sectional configuration of the flow sensor shown in FIG. FIG. 9 is a diagram illustrating a planar configuration of the flow sensor according to the fourth embodiment. FIG. 10 is a diagram showing the XX cross-sectional configuration of the flow sensor shown in FIG. FIG. 11 is a diagram illustrating a planar configuration of the flow sensor according to the fifth embodiment. 12 is a diagram showing a cross-sectional configuration of the flow sensor shown in FIG. 11 taken along line XII-XII. FIG. 13 is a diagram illustrating a planar configuration of a pressure sensor according to another embodiment. FIG. 14 is a diagram showing a cross-sectional configuration of the pressure sensor shown in FIG. FIG. 15 is a diagram illustrating a planar configuration of a temperature sensor according to another embodiment. 16 is a diagram showing a cross-sectional configuration of the temperature sensor shown in FIG. 15 taken along the line XVI-XVI. FIG. 17 is a diagram illustrating a planar configuration of a flow sensor according to another embodiment, 18 is a diagram showing a cross-sectional configuration of the flow sensor shown in FIG. 17 taken along XVIII-XVIII. FIG. 19 is a view showing a cross-sectional configuration of the flow sensor shown in FIG. FIG. 20 is a diagram illustrating a planar configuration of a flow sensor according to another embodiment, FIG. 21 is a view showing a cross-sectional configuration of the flow sensor shown in FIG. 20 taken along XXI-XXI.

Hereinafter, embodiments of the present disclosure will be described with reference to FIGS. In the following embodiments, parts that are the same or equivalent to each other will be described with the same reference numerals.

(First embodiment)
A flow sensor 1 corresponding to the physical quantity sensor according to the first embodiment of the present disclosure will be described with reference to FIGS. 1 to 3K. The flow sensor 1 is a flow meter that detects a flow rate of a fluid, and is a thermal flow meter as an example here. The use of the flow sensor 1 is not limited. For example, the flow sensor 1 is used as an air flow meter (thermal flow meter) that is mounted on an automobile and measures an intake air amount or an exhaust amount of an automobile engine.

As shown in FIGS. 1 and 2, the flow sensor 1 is a sensor having sensing units 7 and 9 for detecting the flow rate of fluid, and includes a first substrate 2, a second substrate 3, and an electric circuit unit. 4, a lead frame 5, and a mold resin 6.

As shown in FIGS. 1 and 2, the first substrate 2 is configured to include a support substrate 20. The support substrate 20 is a plate-like chip made of a semiconductor such as a silicon semiconductor or glass. As shown in FIGS. 1 and 2, the support substrate 20 has one end 2 a and the other end 2 b opposite to the one end 2 a, and one surface 21 and another surface 22 opposite to the one surface 21. Hereinafter, the one surface 21 is referred to as a first surface 21, and the other surface 22 is referred to as a second surface 22. The one end 2a is also called a first end, and the other end 2b is also called a second end.

As shown in FIG. 2, a silicon oxide film 16a is formed on the second surface 22 of the first substrate 2 (hereinafter, the silicon oxide film 16a is referred to as a first silicon oxide film 16a). The first silicon oxide film 16a is formed by plasma CVD or the like.

As shown in FIG. 2, a recess 21a is formed in the first surface 21 on the one end 2a side of the first substrate 2 (hereinafter, the recess 21a is referred to as a first recess 21a). In the flow rate sensor 1 according to the present embodiment, the first recess 21 a is formed, so that a thin portion 22 a is formed on the second surface 22 side of the first substrate 2. Specifically, in the present embodiment, since the first recess 21a is formed, the support substrate 20 is configured to penetrate, and the thin portion 22a includes the first silicon oxide film 16a and a thin film resistor described later. It is comprised by the bodies 7, 8, and 9. The first recess 21a is formed by anisotropic etching or the like. The thickness of the thin portion is, for example, several μm or less.

As shown in FIGS. 1 and 2, the first substrate 2 includes a first surface 21 to a second surface 22 in an inner region of a second recess 31a described later and in a region around the thin portion 22a. A penetrating through hole 23 is formed. Since the through hole 23 is formed, in the flow sensor 1 according to this embodiment, the portion sandwiched between the thin portion 22a and the through hole 23 in the portion around the thin portion 22a in the first substrate 2 is When expanding, the stress due to strain generated on the surface where the first substrate 2 and the second substrate 3 sandwiching the through hole 23 with respect to the thin portion 22a can be expanded into the space in which the through hole 23 is formed. Becomes difficult to be transmitted to the thin portion 22a. Therefore, in the present embodiment, the generation of stress in the first substrate 2 is suppressed, and as a result, stress is hardly generated in the thin portion 22a of the first substrate 2.

As shown in FIG. 1, in the present embodiment, the through hole 23 has a first straight line 23 a and a second straight line as viewed from the direction of the normal to the second surface 22 (the direction of the normal to the paper surface of FIG. 1). 23b and the third straight line 23c form a U-shape. Here, the 2nd straight line 23b is a straight line arrange | positioned on the opposite side to the 1st straight line 23a on both sides of the thin part 22a. Here, as an example, the second straight line 23b is a straight line parallel to the first straight line 23a, but the second straight line 23b is not necessarily a straight line parallel to the first straight line 23a. The third straight line 23c is a straight line connecting the first straight line 23a and the second straight line 23b.

As shown in FIG. 1, in the present embodiment, the through hole 23 is a connection portion between the first straight line 23 a and the third straight line 23 c and the second straight line 23 b when viewed from the direction of the normal to the second surface 22. And the third straight line 23c are bent at right angles.

As shown in FIG. 1, in the present embodiment, the through hole 23 has the other end of the first substrate 2 with the third straight line 23 c sandwiching the thin portion 22 a when viewed from the direction normal to the second surface 22. It is set as the structure arrange | positioned on the opposite side of 2b.

As shown in FIGS. 1 and 2, the second surface 22 of the first substrate 2 has three thin film resistors made of a metal such as aluminum or platinum or silicon partially doped by ion implantation. The bodies 7, 8, and 9 are formed. Specifically, as shown in FIG. 1, on the second surface 22 of the thin portion 22a of the first substrate 2, a thin film resistor 7 is formed on the upstream side of the fluid flow, and a thin film resistor 9 is formed on the downstream side. A thin film resistor 8 is formed at an intermediate position between the thin film resistor 7 and the thin film resistor 9. As shown in FIG. 2, the three thin film resistors 7, 8, and 9 are formed on the upper surface of the first silicon oxide film 16a.

As shown in FIG. 1 and FIG. 2, the three thin film resistors 7 to 9 have different electrode pairs 10 (10a, 10b), 11 (11a, 11b), 12 (12a) disposed on the second surface 22, respectively. , 12b) and is electrically connected to the electric circuit portion 4 by the first bonding wire 14. Each of the three thin film resistors 7 and 9 constitutes a part of a bridge circuit (not shown), and is configured as a sensing unit. The thin film resistor 8 is configured as a heater (heating element) for increasing the difference in temperature detected by the two thin film resistors 7 and 9 which are temperature sensors. The electrode pairs 10 to 12 are made of gold or the like.

In the flow sensor 1 according to the present embodiment, when the fluid passes above the thin portion 22a of the second surface 22 of the first substrate 2 (see the reference numeral Y1 in FIGS. 1 and 2), the sensing portions 7 and 9 are used. Changes the temperature distribution detected by. As a result, the thin film resistor 7 disposed upstream of the thin film resistor 8 serving as a heater is cooled, and the thin film resistor 9 disposed downstream is heated by the heat of the heater (thin film resistor 8). Is done. At this time, the flow rate of the fluid is detected by outputting a resistance value change caused by the temperature difference between the temperatures detected by the two temperature sensors (thin film resistors 7 and 9) as an electrical signal.

Note that, as described above, in the flow sensor 1 according to the present embodiment, the three thin film resistors 7 to 9 are extended over the thin portion 22a, which is a portion of the first substrate 2 having a small heat capacity, so as to be thin. The flow rate of the fluid is detected above the portion 22a. For this reason, in the flow sensor 1 according to the present embodiment, heat such as the heat generated by the heater (thin film resistor 8) is not easily applied to the thin-walled portion 22a, and the thermal response due to a change in the flow rate of the fluid is good. The detection sensitivity of 1 becomes high.

Note that, as shown in FIG. 2, the first substrate 2 is bonded and fixed to the lead frame 5 via a conductive or electrically insulating adhesive 13 on the other end 2b side.

In the flow sensor 1 according to the present embodiment, when the fluid flows above the thin portion 22a of the second surface 22 of the first substrate 2 (see Y1 in FIGS. 1 and 2), two temperatures are used. A temperature difference corresponding to the flow rate of the fluid occurs between the sensors (thin film resistors 7, 9). As a result, the balance of the bridge circuit changes and an electrical change occurs. The flow sensor 1 detects the flow rate of the fluid flowing above the thin portion 22a in the second surface 22 of the first substrate 2 by obtaining this electrical change as an electrical signal corresponding to the fluid flow rate.

The second substrate 3 is a plate-shaped chip made of a semiconductor such as a silicon semiconductor or glass. As shown in FIG. 2, the second substrate 3 has one surface 31 (hereinafter, the one surface 31 is referred to as the third surface 31). The second substrate 3 is bonded to the first substrate 2 while the third surface 31 is in contact with the first surface 21 of the first substrate 2.

1 and 2, the third surface 31 has a recess 31a (hereinafter, the recess 31a is referred to as a second recess 31a). The second recess 31a is formed on the third surface 31 so as to include the thin portion 22a when viewed from the direction of the normal to the second surface 22 (direction of the normal to the paper surface of FIG. 1).

In the flow sensor 1, since the second recess 31 a is formed, a portion of the first surface 21 of the first substrate 2 that is opposed to the second recess 31 a in the outer peripheral portion of the first recess 21 a is second. There is a gap between the second recess 31 a without contacting the third surface 31 of the substrate 3. Thus, in the flow sensor 1 according to the present embodiment, the first substrate 2 is configured to have a gap between the portion around the thin portion 22a and the second substrate 3, and the periphery of the thin portion 22a. The portion other than the portion is fixed by the second substrate 3. Thus, in the flow sensor 1, since the 1st board | substrate 2 is being fixed to the 2nd board | substrate 3 in the part far from the thin part 22a among the 1st board | substrates 2, when fixed in the peripheral part of the thin part 22a As compared with the above, it is difficult to apply stress generated in relation to the second substrate 3 to the thin portion 22a. As a result, in the flow sensor 1 according to the present embodiment, it is difficult for stress to be applied to the thin portion 22a and the thin portion 22a to be deformed to reduce the detection accuracy of the flow sensor.

In the flow sensor 1 according to the present embodiment, when the thickness of the first substrate 2 and the thickness of the second substrate 3 are compared as the length in the direction of the normal to the second surface 22 of the first substrate 2. In addition, the second substrate 3 is thinner than the first substrate 2. For this reason, in the flow sensor 1 according to the present embodiment, when the first substrate 2 and the second substrate 3 expand and contract due to a temperature change, the second substrate 3 is more easily deformed than the first substrate 2, That is, the first substrate 2 is difficult to deform. Therefore, the thin-walled portion 22a is not easily deformed.

Further, the distance between the first surface 21 of the first substrate 2 and the bottom surface of the second recess 31a of the second substrate 3 is set to 100 μm or less. For this reason, in the flow sensor 1 according to the present embodiment, the space formed between the first surface 21 of the first substrate 2 and the bottom surface of the second recess 31a of the second substrate 3 is narrow. Therefore, the Reynolds number of the fluid flowing through the space is reduced, and in the flow sensor 1 according to the present embodiment, the fluid enters the through hole 23 from the outside and eventually enters the second recess 31a of the second substrate 3. However, the infiltrated fluid tends to be laminar rather than turbulent. Therefore, even when the infiltrated fluid reaches the first recess 21a, the fluid is unlikely to cause a vortex in the first recess 21a. It tends to decrease.

The electrical circuit unit 4 is a circuit chip having an electrical circuit that performs arithmetic processing on the electrical signals detected and output by the sensing units 7 and 9. The electric circuit unit 4 is electrically connected to the outside through a second bonding wire 15 connected to an external output connection terminal 5a, which will be described later. As a result of calculation processing by the electric circuit unit 4, The obtained electrical signal is output to the outside. For example, the electric circuit unit 4 performs arithmetic processing for comparing a flow rate signal indicated by an electrical signal detected by two temperature sensors (thin film resistors 7 and 9) and a set flow rate signal in which a predetermined flow rate is set in advance. The resulting electrical signal is output to the outside. As shown in FIGS. 1 and 2, the electric circuit portion 4 is mounted on and supported by a lead frame 5.

The lead frame 5 is made of a metal having excellent conductivity such as Cu or 42 alloy, and is formed by etching or pressing. As shown in FIGS. 1 and 2, the lead frame 5 has an external output connection terminal 5 a for electrical connection between the electric circuit portion 4 and the outside. As shown in FIGS. 1 and 2, the lead frame 5 mounts and supports the second substrate 3 on which the first substrate 2 is loaded and the electric circuit unit 4.

The mold resin 6 is made of a thermosetting resin such as an epoxy resin, and is formed by a transfer molding method using a mold or a compression molding method.

The configuration of the flow sensor 1 according to this embodiment has been described above. Next, a method for manufacturing the flow sensor 1 according to the present embodiment will be described with reference to FIGS. 3A to 3K.

The flow sensor 1 is basically manufactured through a process similar to a general IC manufacturing process. That is, the flow sensor 1 performs dicing and mounting on a wafer completed through the previous process (process for forming wirings such as the sensing units 7 and 9 on the wafer (the first wafer 200 and the second wafer 300)) and the previous process. It is manufactured through a post-process that performs such processing. Therefore, only the characteristic part of the manufacturing method of the flow sensor 1 according to the present embodiment will be described in detail here.

The manufacturing method of the flow sensor 1 according to the present embodiment includes the following first to third steps. The first and second steps are steps included in the preceding step, and the third step is a step included in the subsequent step.

In the first step, the first wafer 200 shown in FIG. 3G is prepared through the steps shown in FIGS. 3A to 3G. That is, a plate-like first wafer 200 having one surface 201 and the other surface 202 opposite to the one surface 201 is prepared as a member constituting the first substrate 2 of the plurality of flow sensors 1. Hereinafter, the one surface 201 is referred to as a fourth surface 201, and the other surface 202 is referred to as a fifth surface 202. As the first wafer 200, a wafer made of a semiconductor or glass is prepared. Here, as an example, the first wafer 200 made of a silicon semiconductor is employed. Here, the fourth surface 201 corresponds to the first surface 21 of the first substrate 2, and the fifth surface 202 corresponds to the second surface 22. Further, as the first wafer 200, a plurality of first recesses 21 a corresponding to the plurality of flow sensors 1 are formed on the fourth surface 201, so that a plurality of thin portions 22 a corresponding to the plurality of flow sensors 1 are formed. A wafer having the structure is prepared. Further, as the first wafer 200, a wafer having a plurality of through holes 23 penetrating from the fourth surface 201 to the fifth surface 202 corresponding to the plurality of through holes 23 corresponding to the plurality of flow sensors 1 respectively. Prepare.

Note that the first wafer 200 having this configuration can be manufactured, for example, by the following procedure. First, as shown in FIG. 3A, a first silicon oxide film 16a is formed on the fifth surface 202 of the first wafer 200 by plasma CVD or the like, and a plurality of flow sensors 1 are formed on the upper surface of the first silicon oxide film 16a. A plurality of thin film resistors 7 to 9 corresponding to each are arranged. Specifically, a plurality of two thin film resistors 7 and 9 made of a metal such as aluminum or platinum or silicon partially doped by ion implantation are formed corresponding to each of the plurality of flow sensors 1. The thin film resistor 8 is patterned at the same time. A plurality of electrode pairs 10 to 12 are arranged on the fifth surface 202 of the first wafer 200. Each of the electrode pairs 10 to 12 is a pad made of gold or the like. Further, a silicon oxide film 16b is formed on the fourth surface 201 of the first wafer 200 by plasma CVD or the like (hereinafter, the silicon oxide film 16b is referred to as a second silicon oxide film 16b), and the second silicon oxide film 16b. The part corresponding to the some 1st recessed part 21a is removed.

Next, as shown in FIG. 3B, a photoresist 17 is applied on the fifth surface 202 of the first wafer 200 so as to cover the thin film resistors 7, 8, 9 and the first silicon oxide film 16a. Next, as shown in FIG. 3C, patterning is performed by development to remove portions of the photoresist 17 corresponding to the plurality of through holes 23. Next, as shown in FIG. 3D, using the photoresist 17 as a mask, portions of the first silicon oxide film 16a corresponding to the plurality of through holes 23 are removed by dry etching or the like. Next, as shown in FIG. 3E, the photoresist 17 is removed with an organic solvent such as acetone. Next, as shown in FIG. 3F, the portion of the first wafer 200 that becomes the through hole 23 is removed by dry etching or the like using the first silicon oxide film 16a as a mask. At this time, since the second silicon oxide film 16b is formed on the fourth surface 201, even if the etching gas introduced from the fifth surface 202 side flows through the through hole 23 to the fourth surface 201 side. The etching gas flow is blocked by the second silicon oxide film 16b. Therefore, the etching gas is suppressed from flowing around to the fourth surface 201 side. Next, as shown in FIG. 3G, by etching the first wafer 200, a portion that becomes the first recess 21 a is removed from the fourth surface 201 of the first wafer 200, and then second etching is performed by dry etching or the like. The silicon oxide film 16b is removed. The first wafer 200 can be manufactured by the above procedure.

In the first step, the second wafer 300 shown in FIG. 3J is prepared through the steps of FIGS. 3H to 3J. That is, a plate-like second wafer 300 having one surface 301 is prepared as a member constituting the second substrate 3 of the plurality of flow sensors 1 (hereinafter, the one surface 301 is referred to as the sixth surface 301). As the second wafer 300, a wafer made of a semiconductor or glass is prepared. Here, as an example, the second wafer 300 made of a silicon semiconductor is employed.

Note that the second wafer 300 having this configuration can be manufactured, for example, by the following procedure. First, as shown in FIG. 3H, a silicon oxide film 18 is formed on the sixth surface 301 of the second wafer 300 by plasma CVD or the like (hereinafter, the silicon oxide film 18 is referred to as a third silicon oxide film 18). Then, portions of the third silicon oxide film 18 corresponding to the plurality of second recesses 31a are removed. Next, as shown in FIG. 3I, the portion of the second wafer 300 that becomes the second recess 31a is removed by dry etching or the like using the third silicon oxide film 18 as a mask. Next, as shown in FIG. 3J, the third silicon oxide film 18 is removed by dry etching or the like. The second wafer 300 can be manufactured by the above procedure.

Thus, in the second step after the first step, the first wafer 200 and the second wafer 300 are brought into contact with the fourth surface 201 as shown in FIG. Paste together. At this time, when viewed from the direction of the normal to the sixth surface 301, each of the plurality of second recesses 31a corresponds to the corresponding thin portion 22a of the plurality of thin portions 22a and the corresponding through hole 23 of the plurality of through holes 23. The first wafer 200 and the second wafer 300 are bonded together so as to be included inward.

Thus, the second step is performed, and the following third step is performed after the second step. In the third step, first, a plurality of workpieces shown in FIG. 3K are obtained by dicing a workpiece having a configuration in which the first wafer 200 and the second wafer 300 are bonded together into individual pieces. Next, each of the plurality of workpieces is bonded to the lead frame 5 via the adhesive 13. In addition, the electric circuit unit 4 is mounted on the lead frame 5. Further, the first bonding wire 14 allows the three thin film resistors 7 to 9 to be electrically connected to the electric circuit unit 4 via different electrode pairs 10 to 12 disposed on the fifth surface 202 of the first wafer 200, respectively. Connect. Then, sealing with the mold resin 6 is performed.

Through the above steps, a plurality of flow sensors 1 are completed. In the manufacturing method described above, in the semiconductor process, the second recess 31a and the through hole 23 which are characteristic parts are formed in the wafer (first and second wafers 200 and 300), and the flow sensor 1 is formed on a single wafer. build up. As described above, in the manufacturing method of the flow rate sensor 1, in the semiconductor process, the second recess 31a that is a characteristic portion is formed in the second wafer 300, and the flow rate sensor 1 is manufactured by a manufacturing technique for forming the flow rate sensor 1 on a single wafer. can do. For this reason, in the manufacturing method of this flow sensor 1, it becomes possible to process simultaneously about several flow sensors 1 by a semiconductor process.

The manufacturing method of the flow sensor 1 according to the present embodiment has been described above. Next, the effect of the structure and manufacturing method of the flow sensor 1 according to the present embodiment described above will be described.

As described above, the flow sensor 1 according to the present embodiment is a flow sensor having the sensing units 7 and 9 that detect the flow rate of the fluid and output it as an electrical signal, and has the following characteristics. The first substrate 2 and the second substrate 3 are provided. That is, the first substrate 2 includes a support substrate 20 having one end 2a and the other end 2b and having a first surface 21 and a second surface 22, and the first surface 21 on the first end 2a side of the support substrate 20 is first on the first surface 21. It has the thin part 22a made thin by forming the recessed part 21a. In addition, the second substrate 3 has a third surface 31, and has a second recess 31 a formed in the third surface 31 so as to include the thin portion 22 a when viewed from the direction of the normal to the second surface 22. The third surface 31 is bonded to the first substrate 2 while being in contact with the first surface 21 of the first substrate 2.

For this reason, in the flow sensor 1 according to the present embodiment, a gap is formed between the portion around the thin portion 22a of the first substrate 2 and the second substrate 3, and the periphery of the thin portion 22a. It is set as the structure fixed by the 2nd board | substrate 3 in parts other than this part. Therefore, compared with the case where the thin portion 22a is fixed at the peripheral portion, the thin portion 22a is less likely to be stressed due to the relationship with the second substrate 3. Thereby, in the flow sensor 1 which concerns on this embodiment, the fall of the detection accuracy of the flow sensor 1 by a stress being added to the thin part 22a and deform | transforming the thin part 22a can be suppressed.

Further, in the flow rate sensor 1 according to the present embodiment, in the first substrate 2, when viewed from the direction of the normal to the second surface 22, an area inside the second recess 31 a and an area around the thin portion 22 a. , A through hole 23 penetrating from the first surface 21 to the second surface 22 is formed.

For this reason, in the flow rate sensor 1 according to the present embodiment, the portion sandwiched between the thin portion 22a and the through hole 23 among the portions around the thin portion 22a in the first substrate 2 is expanded when the through hole is formed. 23 can be expanded into the space in which the first substrate 2 and the second substrate 3 are bonded to the thin portion 22a, and stress due to strain generated on the surface where the first substrate 2 and the second substrate 3 are joined to the thin portion 22a is hardly transmitted to the thin portion 22a. Become. Therefore, in the present embodiment, the generation of stress in the first substrate 2 is suppressed, and as a result, stress is hardly generated in the thin portion 22a of the first substrate 2.

In the flow sensor 1 according to the present embodiment, when the thickness of the first substrate 2 and the thickness of the second substrate 3 are compared as the length in the direction of the normal to the second surface 22 of the first substrate 2. In addition, the second substrate 3 is thinner than the first substrate 2.

For this reason, in the flow sensor 1 according to the present embodiment, when the first substrate 2 and the second substrate 3 expand and contract due to a temperature change, the second substrate is more easily deformed than the first substrate 2, that is, The first substrate 2 becomes difficult to deform, and as a result, the thin portion 22a becomes difficult to deform.

In the flow sensor 1 according to this embodiment, the distance between the first surface 21 of the first substrate 2 and the bottom surface of the second recess 31a of the second substrate 3 is set to 100 μm or less.

For this reason, in the flow sensor 1 according to the present embodiment, the space formed between the first surface 21 of the first substrate 2 and the bottom surface of the second recess 31a of the second substrate 3 is narrow, and the space The Reynolds number for the fluid flowing through Thereby, in the flow sensor 1 according to the present embodiment, the fluid that has entered the second recess 31a from the outside tends to become a laminar flow, and even when the intruded fluid wraps around the first recess 21a, the flow rate The influence on the detection accuracy of the sensor 1 tends to be reduced.

As described above, the method for manufacturing the flow sensor 1 according to the present embodiment includes the following first and second steps. That is, in the first step, first, a plate-shaped first having a fourth surface 201 and a fifth surface 202 opposite to the fourth surface 201 as a member constituting the first substrate 2 of the plurality of flow sensors 1. A wafer 200 is prepared. The fourth surface 201 corresponds to the first surface 21 of the first substrate 2, and the fifth surface 202 corresponds to the second surface 22. Further, as the first wafer 200, a plurality of first recesses 21 a corresponding to the plurality of flow sensors 1 are formed on the fourth surface 201, so that a plurality of thin portions 22 a corresponding to the plurality of flow sensors 1 are formed. A wafer having the structure is prepared. Further, as the first wafer 200, a wafer having a plurality of through holes 23 penetrating from the fourth surface 201 to the fifth surface 202 corresponding to the plurality of thin portions 22 a corresponding to the plurality of flow sensors 1. Prepare. In the first step, a plate-like second wafer 300 having a sixth surface 301 is prepared as a member constituting the second substrate 3 of the plurality of flow sensors 1. In the second step after the first step, the first wafer 200 and the second wafer 300 are bonded together while the sixth surface 301 is in contact with the fourth surface 201. At this time, when viewed from the direction of the normal to the sixth surface 301, each of the plurality of second recesses 31 a corresponds to the corresponding first recess 21 a among the plurality of first recesses 21 a and the corresponding through hole of the plurality of through holes 23. The first wafer 200 and the second wafer 300 are bonded together so as to include the hole 23 inside.

For this reason, in the manufacture of the flow sensor 1 according to the present embodiment, a plurality of flow sensors 1 are manufactured at the same time without separately processing a plurality of members in separate manufacturing steps as in the conventional technique described above. Can do. Thereby, in the flow sensor 1 which concerns on this embodiment, a manufacturing process can be simplified rather than before.

(Second Embodiment)
A second embodiment of the present disclosure will be described with reference to FIGS. 4 to 6. In the present embodiment, the configuration of the through hole 23 is changed with respect to the first embodiment. Since the rest is basically the same as that of the first embodiment, only the parts different from the first embodiment will be described.

In the first embodiment, the through hole 23 has a configuration in which the connecting portion between the first straight line 23a and the third straight line 23c and the connecting portion between the second straight line 23b and the third straight line 23c are bent at right angles. It was. However, as shown in FIGS. 4 and 5, in the present embodiment, the through hole 23 is connected to the connecting portion between the first straight line 23a and the third straight line 23c, and the connecting portion between the second straight line 23b and the third straight line 23c. Each portion has a plurality of portions bent at an obtuse angle.

For this reason, in the flow sensor 1 according to the present embodiment, compared to the case of the first embodiment, the connection portion between the first straight line 23a and the third straight line 23c, or the connection between the second straight line 23b and the third straight line 23c. Stress is difficult to concentrate on the part. As a result, in the flow sensor 1 according to the present embodiment, compared to the case of the first embodiment, during the semiconductor process (for example, during the dicing process), stress is concentrated on these connection portions and the connection portions are cracked. It is difficult to cause problems such as

In the present embodiment, as shown in FIGS. 4 and 5, the electric circuit unit 4 is formed in the second substrate 3. In FIGS. 4 and 5, the thin film resistors 7 and 9 that are sensing units, the thin film resistor 8 that is a heater, the first silicon oxide film 16a, and the like related to electrical connection are not shown. . Here, the through electrode 19 penetrating from the first surface 21 to the second surface 22 for electrically connecting the electric circuit portion 4 and the second bonding wire 15 connected to the external output connection terminal 5a is provided in the first. By providing it on the substrate 2, electrical connection between the electric circuit portion 4 and the outside is made possible. By setting it as such a structure, in the flow sensor 1 which concerns on this embodiment, the size reduction of the flow sensor 1 is attained compared with the case of 1st Embodiment. As shown in FIG. 5, an electrode 19a is provided at the end of the through electrode 19 opposite to the end directed to the electric / BR> C circuit section 4, and the electrode 19a is an electrode pair. 10 and the first bonding wire 14, and the external output connection terminal 5 </ b> A and the second bonding wire 15 are electrically connected.

The configuration of the flow sensor 1 according to this embodiment has been described above. A method for manufacturing the flow sensor 1 according to the present embodiment will be described with reference to FIGS. 6A to 6J.

As in the case of the first embodiment, the flow sensor 1 according to the present embodiment is basically manufactured through the same process as a general IC manufacturing process. That is, the flow sensor 1 is manufactured through the above-described pre-process and post-process. Therefore, as in the first embodiment, only the characteristic part of the method for manufacturing the flow sensor 1 according to this embodiment will be described in detail here.

The manufacturing method of the flow sensor 1 according to the present embodiment includes the following first to third steps. The first and second steps are steps included in the preceding step, and the third step is a step included in the subsequent step.

In the first step, the first wafer 200 shown in FIG. 6G is prepared through the steps shown in FIGS. 6A to 6G. That is, a plate-like first wafer 200 having a fourth surface 201 and a fifth surface 202 is prepared as a member constituting the first substrate 2 of the plurality of flow sensors 1. Here, the first wafer 200 has a plurality of through electrodes 19 penetrating from the fourth surface 201 to the fifth surface 202 corresponding to the plurality of through electrodes 19 corresponding to the plurality of flow sensors 1 respectively. Prepare a wafer.

Note that the first wafer 200 having this configuration can be manufactured, for example, by the following procedure. First, as shown in FIG. 6A, a first silicon oxide film 16a is formed on the fifth surface 202 of the first wafer 200 by plasma CVD or the like, and a plurality of flow sensors 1 are formed on the upper surface of the first silicon oxide film 16a. A plurality of thin film resistors 7 to 9 corresponding to each are arranged. Further, a second silicon oxide film 16b is formed on the fourth surface 201 of the first wafer 200 by plasma CVD or the like, and portions corresponding to the plurality of first recesses 21a in the second silicon oxide film 16b are removed. To do. Next, as shown in FIG. 6B, portions of the first silicon oxide film 16a corresponding to the plurality of through electrodes 19 are removed by dry etching or the like. Next, as shown in FIG. 6C, a portion of the first wafer 200 where the through electrode 19 is formed is removed by dry etching using the first silicon oxide film 16a as a mask. Next, as shown in FIG. 6D, the through electrode 19 is formed by metal plating such as copper on a portion of the first wafer 200 that is removed as a portion where the through electrode 19 is formed. Next, as shown in FIG. 6E, the electrode pair 10 and the electrode 19a are arranged. Next, as shown in FIG. 6F, after removing portions of the first silicon oxide film 16a corresponding to the plurality of through holes 23 by dry etching or the like, dry etching or the like using the first silicon oxide film 16a as a mask is performed. The portion of the first wafer 200 that becomes the through hole 23 is removed. At this time, as in the case of the first embodiment, since the second silicon oxide film 16b is formed on the fourth surface 201, the etching gas is suppressed from flowing around to the fourth surface 201 side. . Next, as shown in FIG. 6G, the first wafer 200 is etched to remove the portion to be the first recess 21a on the fourth surface 201 of the first wafer 200, and then the second wafer 200 is dry-etched or the like. The silicon oxide film 16b is removed. The first wafer 200 can be manufactured by the above procedure.

In the first step, the second wafer 300 shown in FIG. 6I is prepared through the steps shown in FIGS. 6H and 6I. That is, a plate-like second wafer 300 having a sixth surface 301 is prepared as a member constituting the second substrate 3 of the plurality of flow sensors 1. Since the second wafer 300 can be manufactured by the same method as in the first embodiment, the description of the manufacturing method of the second wafer 300 is omitted here.

Thus, the first step is performed, and in the second step after the first step, as in the case of the first embodiment, the sixth surface 301 is brought into contact with the fourth surface 201 as shown in FIG. 6J. The first wafer 200 and the second wafer 300 are bonded together.

Then, the following third step is performed after the second step. Since the third step is the same as in the case of the first embodiment, the description of the third step is omitted here.

Through the above steps, a plurality of flow sensors 1 are completed. In the manufacturing method described above, similarly to the first embodiment, in the semiconductor process, the second recess 31a and the through hole 23 are formed in the wafer (first and second wafers 200 and 300), and the flow sensor 1 is formed as a single unit. Create on the wafer. For this reason, in the manufacturing method of this flow sensor 1, it becomes possible to process simultaneously about several flow sensors 1 by a semiconductor process. In particular, in the manufacturing method according to the present embodiment, the through electrode 19 can be formed in the same process as the process of forming the through hole 23. Therefore, in this manufacturing method, the flow sensor 1 having a configuration in which the through electrode 19 for enabling the electrical connection between the electric circuit unit 4 and the outside is provided on the first substrate 2 can be manufactured efficiently. it can.

(Third embodiment)
A third embodiment of the present disclosure will be described with reference to FIGS. In the present embodiment, the configuration of the through hole 23 is changed with respect to the second embodiment. Since the other parts are basically the same as those of the second embodiment, only portions different from those of the second embodiment will be described.

In the second embodiment, the through hole 23 has a plurality of bent portions, each of the connecting portion between the first straight line 23a and the third straight line 23c and the connecting portion between the second straight line 23b and the third straight line 23c. Was configured. However, as shown in FIGS. 7 and 8, in the present embodiment, the through hole 23 is connected to the connecting portion between the first straight line 23a and the third straight line 23c, and the connecting portion between the second straight line 23b and the third straight line 23c. Each of the portions has a curved portion. In FIGS. 7 and 8, the thin film resistors 7 and 9 that are sensing units, the thin film resistor 8 that is a heater, the first silicon oxide film 16a, and the electrode pairs 10 to 12 are related to electrical connection. The illustration is omitted.

For this reason, in the flow sensor 1 according to the present embodiment, the connection portion between the first straight line 23a and the third straight line 23c and the connection between the second straight line 23b and the third straight line 23c are further increased than in the second embodiment. Stress is difficult to concentrate on the part. As a result, in the flow sensor 1 according to the present embodiment, compared to the second embodiment, stress is concentrated on these connection portions during the semiconductor process (for example, during the dicing process), and the connection portions are Problems such as cracking are less likely to occur.

(Fourth embodiment)
A fourth embodiment of the present disclosure will be described with reference to FIGS. 9 and 10. In the present embodiment, the configuration of the through hole 23 is changed with respect to the first embodiment. Since the rest is basically the same as that of the first embodiment, only the parts different from the first embodiment will be described.

In the first embodiment, the through hole 23 is configured such that the third straight line 23c is disposed on the opposite side of the other end 2b of the first substrate 2 with the thin portion 22a interposed therebetween. However, in this embodiment, as shown in FIGS. 9 and 10, the through hole 23 is configured such that the third straight line 23 c is disposed on the opposite side of the one end 2 a of the first substrate 2 with the thin portion 22 a interposed therebetween. ing.

For this reason, in the present embodiment, the stress generated in the relationship between the second substrate 3 and the portion of the first substrate 2 on the other end 2 b side (hereinafter referred to as the other end-induced stress) passes around the through hole 23. Thus, the light is transmitted to the thin portion 22a through a path that goes around the region between the first straight line 23a and the second straight line 23b. That is, the stress at the other end is transmitted through a path as indicated by an arrow Y2 in FIG. Therefore, in this embodiment, the transmission path until the other end-induced stress reaches the thin portion 22a is longer than that in the first embodiment. Therefore, in the flow sensor 1 according to the present embodiment, the stress due to the other end is easily absorbed by the time it reaches the thin portion 22a, and the stress concentration on the thin portion 22a is easily relaxed.

(Fifth embodiment)
A fifth embodiment of the present disclosure will be described with reference to FIGS. 11 and 12. In the present embodiment, the through hole 23 is omitted and the shape of the second recess 31a is changed with respect to the second embodiment. Since the other parts are basically the same as those of the second embodiment, only portions different from those of the second embodiment will be described.

As shown in FIGS. 11 and 12, in the flow sensor 1 according to this embodiment, the second recess 31 a is located on the side of the one end 2 a of the second substrate 3 when viewed from the direction of the normal to the second surface 22. It is formed so as to include the entire portion. Therefore, in the present embodiment, the second substrate 3 is not brought into contact with the first surface 21 in the portion on the one end 2a side of the third surface 31 due to the formation of the second recess 31a. Of the three surfaces 31, at least a part of the portion on the other end 2 b side is brought into contact with the first surface 21. In the example of FIGS. 11 and 12, the second recess 31a is formed so as to be connected from the lower end to the upper end in the vertical direction of FIG. 11 and to the right end in the horizontal direction of FIG. Is formed.

As described above, in the present embodiment, the second substrate 3 is not brought into contact with the first surface 21 in the portion on the one end 2a side of the third surface 31 by forming the second recess 31a. The third surface is in contact with the first surface 21 in at least a part of the portion on the other end 2b side.

For this reason, in the flow sensor 1 according to the present embodiment, no stress is generated due to the relationship between the second substrate 3 and the portion of the first substrate 2 on the one end 2a side, and the stress caused by the other end is Is not transmitted to the portion on the one end 2a side. Therefore, in the flow sensor 1 according to the present embodiment, stress concentration on the thin portion 22a is suppressed even if the through hole 23 is not formed. Note that the through hole 23 may be formed in the flow sensor 1 according to the present embodiment.

(Other embodiments)
The present disclosure is not limited to the above-described embodiment, and can be appropriately changed within the scope described in the claims.

For example, in the first to fourth embodiments, the flow sensor 1 has a configuration in which the through hole 23 is formed. However, the flow sensor 1 according to the first to fourth embodiments may have a configuration in which the through hole 23 is not formed.

In the second, third, and fifth embodiments, the electric circuit unit 4 is manufactured in the second substrate 3. In the first and fourth embodiments, the electric circuit unit 4 is manufactured on the second substrate 3. It may be configured.

In the first to fifth embodiments, the thin portion 22a is configured by the first silicon oxide film 16a and the thin film resistors 7, 8, and 9. However, the configuration of the thin portion 22a is not limited to this configuration. . For example, in the first to fourth embodiments, the thin portion 22a may be constituted by the constituent material of the support substrate 20.

In the first to fifth embodiments, as shown in FIGS. 3K and 6J, in the manufacturing process, the second and third silicon oxide films 16b and 18 are removed, and the first substrate 2 and the second substrate 3 are connected. I was pasting them together. However, in the first to fifth embodiments, the second and third silicon oxide films 16b and 18 may be left without being removed. In this case, the second silicon oxide film 16b and the third silicon oxide film 18 are brought into contact (adhesion), and the first substrate 2 and the second substrate 3 are bonded together by the adhesive force between the oxide films 16b and 18. It can be set as the flow sensor 1 of a structure. In this case, the number of manufacturing steps is reduced as compared with the first to fifth embodiments, and the flow sensor 1 can be easily manufactured.

In the first to fifth embodiments, an example in which the present disclosure is applied to the flow sensor 1 has been described. However, the present disclosure may be applied to a physical quantity sensor other than the flow sensor.

That is, for example, as shown in FIGS. 13 and 14, the present disclosure may be applied to the pressure sensor 1A. This pressure sensor 1A is obtained by changing the basic configuration to a pressure sensor in the flow sensor 1 according to the first embodiment. Specifically, the sensing units 7 and 9 for detecting the flow rate of the fluid are changed to a sensing unit 7A configured by a piezoresistor or the like for detecting the pressure by the detection target, and the pressure reference chamber is configured. A third substrate 20A having a concave portion (see reference numeral 21A in FIG. 14) is provided on the other surface 22 side of the first substrate 2. In the pressure sensor 1A, the through hole 23 is not formed. And also in this pressure sensor 1A, the 2nd recessed part 31a formed in the 3rd surface 31 of the 2nd board | substrate 3 is formed so that the thin part 22a may be included like the flow sensor 1 in 1st Embodiment. . A vent hole 22 </ b> A is formed on the bottom surface of the second recess 31 a of the second substrate 3 so as to penetrate from the bottom surface of the second recess 31 a to the surface 32 of the second substrate 3 opposite to the third surface 31. . The vent hole 22A is an inlet through which a fluid to be measured flows. In the pressure sensor 1A, a fluid that is a detection object sequentially enters the second recess 31a of the second substrate 3 and the first recess 21a of the first substrate 2 from the air hole 22A, and the thin portion 22a is caused by the pressure of the fluid. When the piezoresistor formed in (1) changes, the pressure is detected by outputting an electric signal corresponding to the pressure. Since the air hole 22A has a very small size (for example, the diameter of the hole is several μm to several tens μm), the air hole 22A is provided in the air hole 22A as in the case of the prior art (the flow sensor described in Patent Document 1). It is difficult for foreign matter (metal scraps, organic matter, etc.) to enter the surface. This air hole 22A can be formed by dry etching or the like. Also in this pressure sensor 1A, as in the case of the flow rate sensor 1 in the first embodiment, compared to the case where the pressure sensor 1A is fixed at the peripheral portion of the thin portion 22a, the second substrate 3 and the thin portion 22a are fixed. It becomes difficult to apply the stress caused by the relationship.

The members (see reference numeral 30A in FIGS. 13 and 14) arranged around the first substrate 2 are formed integrally with the mold resin 6 when the mold resin 6 is molded. is there. The member 30A is molded so as to be in close contact with the second substrate 3 at the time of molding the mold. Here, after molding, the first of the mold resin constituting the member 30A around the first substrate 2 is formed. The portion that has been in contact with the substrate 2 is removed by the laser irradiation. Thereby, in this flow sensor 1, as shown in FIG. 13, a gap 31A is formed between the member 30A and the first substrate 2, and since this gap 31A is formed, at least a part of the member 30A is the first. 1 is separated from the substrate 2.

As described above, in the pressure sensor 1A, when the gap 30A is formed and at least a part of the member 30A is separated from the first substrate 2, the member 30A is in close contact with the first substrate 2. As compared with the above, it is difficult to apply stress generated in relation to the member 30A to the thin portion 22a. The member 30A functions as a portion that protects the first substrate 2.

Similarly, as shown in FIGS. 15 and 16, the present disclosure may be applied to the temperature sensor 1B. This temperature sensor 1B is obtained by changing the basic configuration of the flow rate sensor 1 according to the first embodiment to a temperature sensor. Specifically, the sensing units 7 and 9 for detecting the flow rate of the fluid are changed to a sensing unit 7B composed of a thermistor for detecting the temperature of the detection target, and a recess (reference numeral in FIG. 16). 21B) is provided on the other surface 22 side of the first substrate 2. As in the case of the pressure sensor 1A, the bottom surface of the second recess 31a of the second substrate 3 extends from the bottom surface of the second recess 31a to the surface 32 of the second substrate 3 opposite to the third surface 31. A penetrating air hole 22B is formed. In this temperature sensor 1B, the fluid that is the detection object enters the second recess 31a of the second substrate 3 and the first recess 21a of the first substrate 2 in order from the air hole 22B, and the temperature of the thermistor depends on the temperature of the fluid. When the resistance changes, the pressure is detected by outputting an electric signal corresponding to the temperature. The vent hole 22B is an inlet through which a fluid as a measurement object flows. Since the vent hole 22B has a very small size (for example, the diameter of the hole is several μm to several tens μm), the vent hole 22B is provided in the vent hole 22B as in the case of the prior art (the flow sensor described in Patent Document 1). It is difficult for foreign matter (metal scraps, organic matter, etc.) to enter the surface. The vent hole 22B can be formed by dry etching or the like. Also in this pressure sensor 1A, as in the case of the flow rate sensor 1 in the first embodiment, compared to the case where the pressure sensor 1A is fixed at the peripheral portion of the thin portion 22a, the second substrate 3 and the thin portion 22a are fixed. It becomes difficult to apply the stress caused by the relationship.

The members (see reference numeral 30B in FIGS. 15 and 16) arranged around the first substrate 2 are formed integrally with the mold resin 6 when the mold resin 6 is molded. is there. As shown in FIGS. 15 and 16, also in this temperature sensor 1B, as in the case of the pressure sensor 1A, the gap 31B is formed so that at least a part of the member 30B is separated from the first substrate 2. Therefore, compared to the case where the member 30B is in close contact with the first substrate 2, it is difficult to apply the stress generated in relation to the member 30B to the thin portion 22a. The member 30B also functions as a part that protects the first substrate 2.

Further, in the flow rate sensor 1 according to the first to fifth embodiments, as shown in FIGS. 17 and 18, a rectifying plate 30 for adjusting the flow of the fluid to be measured may be provided. The rectifying plate 30 is made of a mold resin, and out of the periphery of the first substrate 2, the fluid upstream of the sensing units 7 and 9 in the direction of the second surface 22 of the first substrate 2 and the sensing unit 7. , 9 are arranged in close contact with the first substrate 2 on the downstream side. Specifically, the current plate 30 is made of a thermosetting resin such as an epoxy resin, and can be formed by a transfer molding method using a mold or a compression molding method. In the first embodiment, in the same step as the step of forming the mold resin 6 for sealing the portion on the other end 2b side of the first substrate 2, the mold resin constituting the rectifying plate 30 is formed, that is, the first step. By integrally molding the mold resin 6 that seals the portion on the other end 2b side of the substrate 2 and the mold resin that constitutes the rectifying plate 30, the number of manufacturing steps can be reduced.

Here, as shown in FIGS. 17 to 19, in this flow sensor 1, the rectifying plate 30 is disposed in close contact with the second substrate 3, but the first substrate 2 has a through hole 23 formed therein. Therefore, the stress caused by the expansion and contraction of the rectifying plate 30 is not easily transmitted to the thin portion 22 a of the first substrate 2. As shown in FIG. 19, since the fluid cannot be rectified when the first substrate 2 protrudes upward in the drawing from the rectifying plate 30, in this flow sensor 1, the end of the rectifying plate 30 is It protrudes upward in the figure from one substrate 2.

It should be noted that rectification is performed only on one of the fluid upstream side of the sensing units 7 and 9 and the downstream side of the sensing units 7 and 9 in the direction of the second surface 22 of the first substrate 2 in the periphery of the first substrate 2. A plate 30 may be provided.

Further, in the flow sensor 1 provided with the rectifying plate 30, as shown in FIGS. 20 and 21, a portion of the mold resin constituting the rectifying plate 30 that is in contact with the first substrate 2 around the first substrate 2. May be removed by laser irradiation. In other words, in the flow sensor 1, the mold resin constituting the rectifying plate 30 is irradiated with a laser along the boundary between the rectifying plate 30 and the first substrate 2 on the first substrate 2 to be positioned around the first substrate 2. The mold resin to be removed may be removed. In this case, in this flow sensor 1, as shown in FIGS. 20 and 21, a gap 40 is formed between the rectifying plate 30 and the first substrate 2. At least a portion is separated from the first substrate 2. Here, the current plate 30 is fixed by being integrated with the mold resin 6.

As described above, in this flow sensor 1, since the gap 40 is formed, at least a part of the rectifying plate 30 is separated from the first substrate 2, so that the rectifying plate 30 is in close contact with the first substrate 2. Compared with the case where it exists, the stress which arises by the relationship with the baffle plate 30 with respect to the thin part 22a becomes difficult to apply. In addition, although there is a concern that the flow of the fluid is hindered by the fluid flowing into the gap 40, the gap 40 is formed by the irradiation of the laser. The width of the gap 40 can be narrowed only by adjusting the laser or the like. That is, by narrowing the width of the gap 40, a problem that the flow of the fluid is inhibited due to the fluid flowing into the gap 40 is less likely to occur.

The embodiments, configurations, and aspects of the present disclosure have been illustrated above, but the embodiments, configurations, and aspects according to the present disclosure are not limited to the above-described embodiments, configurations, and aspects. For example, embodiments, configurations, and aspects obtained by appropriately combining technical units disclosed in different embodiments, configurations, and aspects are also included in the scope of the embodiments, configurations, and aspects according to the present disclosure.

Claims (15)

1. A second surface having a first end (2a) and a second end (2b) opposite to the first end (2a) and opposite to the first surface (21) and the first surface (21) A thin substrate (22a) comprising a first recess (21a) of the first surface (21) on the first end (2a) side of the support substrate (20). A first substrate (2) having
   A second recess having a third surface (31) and including the thin-walled portion (22a) as viewed from the direction of the normal to the second surface (22). (3a) and the second substrate (3) bonded to the first substrate (2) while the third surface (31) is in contact with the first surface (21) of the first substrate (2). )When,
   A physical quantity sensor provided on the second surface (22) of the thin-walled part (22a) and having a sensing part (7, 9, 7A, 7B) that detects a physical quantity of the detection target and outputs it as an electrical signal.
2. The physical quantity sensor according to claim 1, comprising the sensing unit (7, 9) that detects a flow rate of a fluid as a physical quantity of the detected object.
3. The first substrate (2) is in close contact with the first substrate (2) on at least one of the upstream side and the downstream side of the fluid in the direction of the second surface (22) of the first substrate (2) in the periphery of the first substrate (2). The physical quantity sensor according to claim 2, further comprising a baffle plate (30) arranged to adjust the flow of the fluid.
4. The mold resin having a mold resin (6) for sealing a portion of the first substrate (2) on the second end (2b) side, and constituting the mold resin (6) and the current plate (30) The physical quantity sensor according to claim 3, wherein (6) is integrally formed.
5. When comparing the thickness of the first substrate (2) and the thickness of the second substrate (3) as the length in the direction of the normal to the second surface (22), the second substrate (3) The physical quantity sensor according to claim 1, wherein the physical quantity sensor is thinner than the first substrate.
6. The second substrate (3) includes the second recess (31a), and is not in contact with the first surface (21) in a portion of the third surface (31) on the first end (2a) side. The at least part of the third surface (31) on the second end (2b) side is in contact with the first surface (21). The physical quantity sensor described in 1.
7. An electric circuit unit (4) provided in the second substrate (3) and having an electric circuit for performing arithmetic processing on an electric signal detected and output by the sensing unit (7, 9, 7A, 7B);
   The first substrate (2) provided on the first substrate (2) for enabling electrical connection between the electric circuit portion (4) and the outside from the first surface (21) to the second. The physical quantity sensor according to any one of claims 1 to 6, further comprising a through electrode (19) penetrating to the surface (22).
8. The first substrate (2) is an inner region of the second recess (31a) and around the thin portion (22a) when viewed from the direction of the normal to the second surface (22). In the region, provided with a through hole (23) penetrating from the first surface (21) to the second surface (22),
   The physical quantity sensor according to any one of claims 2 to 4, wherein the through hole (23) partially surrounds the periphery of the thin portion (22a).
9. The through hole (23) has a first straight line (23a) and the first straight line (23a) sandwiching the thin portion (22a) when viewed from the direction of the normal to the second surface (22). The second straight line (23b) disposed on the opposite side and the third straight line (23c) connecting the first straight line (23a) and the second straight line (23b) are provided in a U-shape. ,
   When viewed from the direction of the normal to the second surface (22), the connecting portion of the first straight line (23a) and the third straight line (23c), and the second straight line (23b) and the third straight line The physical quantity sensor according to claim 8, wherein each of the connecting portions to (23 c) has a plurality of portions bent at an obtuse angle.
10. The through hole (23) has a first straight line (23a) and the first straight line (23a) sandwiching the thin portion (22a) when viewed from the direction of the normal to the second surface (22). The second straight line (23b) disposed on the opposite side and the third straight line (23c) connecting the first straight line (23a) and the second straight line (23b) are provided in a U-shape. ,
    When viewed from the direction of the normal to the second surface (22), the connecting portion of the first straight line (23a) and the third straight line (23c), and the second straight line (23b) and the third straight line The physical quantity sensor according to claim 8, wherein each of the connecting portions with (23 c) has a curved portion.
11. The through hole (23) has a first straight line (23a) and the first straight line (23a) sandwiching the thin portion (22a) when viewed from the direction of the normal to the second surface (22). The second straight line (23b) disposed on the opposite side and the third straight line (23c) connecting the first straight line (23a) and the second straight line (23b) are provided in a U-shape. ,
    When viewed from the direction of the normal to the second surface (22) of the first substrate (2), the third straight line (23c) is formed on the first substrate (2) with the thin portion (22a) in between. 11. The physical quantity sensor according to claim 8, wherein the physical quantity sensor is disposed on the opposite side of the first end (2a).
12. The distance between the first surface (21) of the first substrate (2) and the bottom surface of the second recess (31a) of the second substrate (3) is 100 µm or less. The physical quantity sensor according to claim 1.
13. A method of manufacturing a physical quantity sensor according to any one of claims 1 to 12,
    The member constituting the first substrate (2) of the plurality of physical quantity sensors has a plate shape having a fourth surface (201) and a fifth surface (202) opposite to the fourth surface (201). A plurality of the first recesses (21a) corresponding to the plurality of physical quantity sensors are formed on the fourth surface (201), whereby the first wafer (200) having the plurality of thin portions (22a) is formed. To prepare,
    As a member constituting the second substrate (3) of the plurality of physical quantity sensors, a plate shape having a sixth surface (301) is formed, and the plurality of second recesses (31a) corresponding to the plurality of physical quantity sensors, respectively. Preparing a second wafer (300) formed on the sixth surface (301);
    After preparing the first wafer (200) and the second wafer (300), each of the plurality of second recesses (31a) is a plurality of the plurality of second recesses (31a) when viewed from the direction of the normal to the sixth surface (301). The first wafer (301) is brought into contact with the fourth surface (201) so that the corresponding first recess (21a) among the first recesses (21a) is included inward. 200) and the second wafer (300) are bonded together.
14. A method of manufacturing a physical quantity sensor according to any one of claims 8 to 11,
    The member constituting the first substrate (2) of the plurality of physical quantity sensors has a plate shape having a fourth surface (201) and a fifth surface (202) opposite to the fourth surface (201). The plurality of first recesses (21a) corresponding to the plurality of physical quantity sensors are formed on the fourth surface (201), whereby the plurality of thin portions (22a) corresponding to the plurality of physical quantity sensors, respectively. A plurality of through-holes penetrating from the fourth surface (201) to the fifth surface (202) in correspondence with the plurality of thin portions (22a) corresponding to the plurality of physical quantity sensors, respectively. 23) providing a first wafer (200) having
    As a member constituting the second substrate (3) of the plurality of physical quantity sensors, a plate shape having a sixth surface (301) is formed, and the plurality of second recesses (31a) corresponding to the plurality of physical quantity sensors, respectively. Preparing a second wafer (300) formed on the sixth surface (301);
    After preparing the first wafer (200) and the second wafer (300), each of the plurality of second recesses (31a) is a plurality of the plurality of second recesses (31a) when viewed from the direction of the normal to the sixth surface (301). The sixth surface so as to include the corresponding through hole (23) of the first recess (21a) and the corresponding through hole (23) among the plurality of through holes (23). Bonding the first wafer (200) and the second wafer (300) while bringing (301) into contact with the fourth surface (201).
15. It is a manufacturing method of the physical quantity sensor according to claim 5,
    The member constituting the first substrate (2) of the plurality of physical quantity sensors has a plate shape having a fourth surface (201) and a fifth surface (202) opposite to the fourth surface (201). A first wafer (200) is prepared, and a plurality of through electrodes (19) corresponding to the plurality of physical quantity sensors are formed on the first wafer (200), and a plurality of corresponding to the plurality of physical quantity sensors are formed. The first recess (21a) is formed in the first wafer (200) to prepare the first wafer (200) having a plurality of the through electrodes (19) and a plurality of the thin portions (22a). To do
    As a member constituting the second substrate (3) of the plurality of physical quantity sensors, a plate shape having a sixth surface (301) is formed, and the plurality of second recesses (31a) corresponding to the plurality of physical quantity sensors, respectively. Preparing a second wafer (300) formed on the sixth surface (301);
    After preparing the first wafer (200) and the second wafer (300), each of the plurality of second recesses (31a) is a plurality of the plurality of second recesses (31a) when viewed from the direction of the normal to the sixth surface (301). The first wafer (301) is brought into contact with the fourth surface (201) so that the corresponding first recess (21a) among the first recesses (21a) is included inward. 200) and the second wafer (300) are bonded together.

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