WO2017217150A1

WO2017217150A1 - Pressure sensor

Info

Publication number: WO2017217150A1
Application number: PCT/JP2017/017876
Authority: WO
Inventors: 由香利白旗
Original assignee: 株式会社デンソー
Priority date: 2016-06-14
Filing date: 2017-05-11
Publication date: 2017-12-21

Abstract

The shape of an upper surface of an inner wall surface of a supporting portion (15), in other words the shape of a diaphragm (14) formed by a recessed portion (13), is made to be a polygonal shape having four or more sides, for example an octagonal shape. Making the shape of the upper surface of the inner wall surface of the supporting portion (15) a polygonal shape having four or more sides in this way allows the diaphragm (14) to distort by a greater amount with respect to the application of pressure than if a circular shape is employed, thereby making it possible to improve the sensitivity of a pressure sensor (S1).

Description

Pressure sensor

Cross-reference to related applications

This application is based on Japanese Patent Application No. 2016-118258 filed on June 14, 2016 and Japanese Patent Application No. 2017-24339 filed on February 13, 2017. The description is incorporated by reference.

The present disclosure relates to a pressure sensor in which a piezoresistor is arranged on a diaphragm formed on a semiconductor substrate, and a detection signal corresponding to the pressure is output using a change in the resistance value of the piezoresistor according to the pressure. .

Conventionally, as this type of pressure sensor, for example, one described in Patent Document 1 has been proposed. In this pressure sensor, an annular support portion is formed by simultaneously removing the outer edge portion and the diaphragm portion on the back surface side of the sensor substrate, and a circular diaphragm is formed inside the support portion. In this way, when the sensor substrate is bonded to the support member by using the annular support portion, the zero shift caused by the change in temperature and static pressure based on the reduction in area and symmetry of the bonded portion, that is, Suppresses the effect of zero point offset on thermal stress and mounting stress.

JP-A-6-258164

However, when the support portion formed on the sensor substrate has an annular shape, it is effective for suppressing the offset of the zero point with respect to the thermal stress and the mounting stress, but the sensitivity to the pressure application is lowered. That is, the magnitude of sensor output obtained with respect to pressure application is reduced.

In view of the above points, it is an object of the present disclosure to provide a pressure sensor having a structure capable of further increasing sensitivity while suppressing the zero point offset with respect to thermal stress and mounting stress.

A pressure sensor according to one aspect of the present disclosure is a chip made of a semiconductor having a rectangular plate shape, and a first concave portion is formed on a back surface, and a thin portion on a front surface side corresponding to the first concave portion is used as a diaphragm. The sensor chip is configured and includes a sensor chip having a piezoresistance on the surface and a bonding member bonded to the support part on the back surface of the sensor chip. In such a configuration, the second recess is formed on the back surface of the sensor chip, the upper surface shape of the outer wall surface of the support portion is a polygonal shape of a quadrangle or more, and the inner wall surface of the support portion that forms the diaphragm shape. The upper surface shape is a polygonal shape that is equal to or greater than a quadrangle.

Thus, the shape of the upper surface of the inner wall surface of the support portion, that is, the shape of the diaphragm constituted by the recesses is made polygonal. As described above, when the upper surface shape of the inner wall surface of the support portion is a polygonal shape, it is possible to increase the amount of distortion of the diaphragm with respect to the pressure application as compared to the circular shape, thereby improving the sensitivity of the pressure sensor. It becomes possible.

In the pressure sensor according to another aspect of the present disclosure, the second recesses are formed at the four corners of the back surface of the sensor chip, the upper surface shape of the outer wall surface of the support portion is circular, and the support that forms the shape of the diaphragm The upper surface shape of the inner wall surface of the part is a polygonal shape of a quadrangle or more.

Thus, even when the upper surface shape of the outer wall surface of the support portion is circular, the pressure sensor according to one aspect of the present disclosure is obtained by making the upper surface shape of the inner wall surface of the support portion a polygonal shape that is equal to or greater than a quadrangle. The same effect can be obtained.

A pressure sensor according to still another aspect of the present disclosure includes an adhesive that is disposed between the sensor chip and the bonding member, and bonds the support portion and the bonding member. By providing a non-formation region where no adhesive is formed, the outer shape viewed from the surface side of the sensor chip is made to be a polygonal shape of a square or more or a circle.

Thus, the outer shape of the adhesive may be different from that of the sensor chip, and the substantial shape of the outer wall surface of the sensor chip may be defined by the shape of the adhesive. Even if it does in this way, the effect similar to the pressure sensor in one viewpoint of this indication can be acquired.

It is a figure which shows the layout of the pressure sensor concerning 1st Embodiment. It is a side view of the pressure sensor shown in FIG. FIG. 3 is a cross-sectional view taken along the line IIIA-IIIA in FIG. FIG. 3 is a cross-sectional view taken along line IIIB-IIIB in FIG. It is a figure which shows the layout of the pressure sensor concerning 2nd Embodiment. It is a side view of the pressure sensor shown in FIG. FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 4. It is a figure which shows the layout of the pressure sensor concerning 3rd Embodiment. It is a side view of the pressure sensor shown in FIG. It is sectional drawing in the IX-IX line in FIG. It is a figure which shows the layout of the pressure sensor concerning 4th Embodiment. It is sectional drawing in the XI-XI line in FIG. It is a figure which shows the layout of the pressure sensor concerning 5th Embodiment. It is a side view of the pressure sensor shown in FIG. It is sectional drawing in the XIV-XIV line | wire in FIG. It is a figure which shows the layout of the pressure sensor concerning 6th Embodiment. It is a side view of the pressure sensor shown in FIG. It is sectional drawing in the XVII-XVII line in FIG. It is sectional drawing of the pressure sensor at the time of making a granular member contain in the adhesive agent demonstrated by other embodiment.

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

(First embodiment)
The pressure sensor according to the first embodiment will be described. This pressure sensor is applied to, for example, measurement of pressure of a pressure medium such as corrosive liquid or gas. Specifically, the pressure sensor measures the exhaust gas pressure in the exhaust pipe of a diesel engine vehicle, and measures the differential pressure before and after a DPF (abbreviation of diesel particulate filter) as an exhaust purification filter provided in the exhaust pipe. Applicable to etc.

Hereinafter, the pressure sensor of the present embodiment will be described with reference to FIGS. 1, 2, 3A, and 3B. 1 is a layout diagram corresponding to the cross-sectional view taken along the line II in FIG. Further, FIG. 2 is not a cross-sectional view, but is hatched for convenience of understanding.

As shown in FIGS. 1 to 3A and 3B, the pressure sensor S1 of the present embodiment includes a semiconductor diaphragm sensor chip 10 and a wiring board 20 as a bonding member bonded to the sensor chip 10. .

The sensor chip 10 is a chip made of a semiconductor such as Si (silicon) having a rectangular plate shape having a front surface 11 and a back surface 12, and is constituted by a silicon substrate whose surface orientation is the <110> plane, for example. ing. In the case of this embodiment, the sensor chip 10 has a square upper surface shape when viewed from the normal direction of the surface 11.

A recess 13 is formed on the center side of the back surface 12 of the sensor chip 10. For example, the recess 13 is formed by chemical etching or the like. Since such a concave portion 13 is formed, a portion of the sensor chip 10 where the concave portion 13 is formed is a thin portion, and a diaphragm 14 is configured by the thin portion.

Further, the periphery of the recess 13 in the sensor chip 10 is a support portion 15 that is thicker than the diaphragm 14. Furthermore, in the case of this embodiment, the recessed part 16 is also formed in the outer edge of the support part 15, and the external shape of the support part 15 becomes a predetermined shape.

In the case of the present embodiment, the recess 13 has a rotationally symmetric polygonal shape with the center of the recess 13 as the center of rotation, here an octagon. Specifically, the recess 13 is a symmetrical octagon with a perpendicular bisector of each side of the octagon formed by the recess 13 as a symmetry line, and is preferably a regular octagon.

Thus, since the recess 13 is formed in an octagon, the diaphragm 14 is also formed in an octagon. And the piezoresistor 17 which comprises the strain gauge which consists of diffused resistance etc. is provided in the position made into the diaphragm 14 in the surface 11 of the sensor chip 10. FIG. For example, a plurality of piezoresistors 17 are provided, and in the present embodiment, four piezoresistors 17a to 17d are provided. The

piezoresistors

17a and 17b are arranged to face each other on both sides in one direction on the surface of the sensor chip 10 with the center position of the diaphragm 14 as the center. In addition, one

piezoresistor

17c and 17d is disposed opposite to each other on both sides in the other direction, which is a direction perpendicular to one direction. A total of four piezoresistors 17a to 17d constitute a Wheatstone bridge circuit. Two

piezoresistors

17a and 17b arranged opposite to both sides in one direction are side gauges arranged on the outer peripheral side in the diaphragm 14. In addition, two

piezoresistors

17c and 17d disposed opposite to both sides in the other direction are center gauges disposed on the inner peripheral side of the diaphragm 14 with respect to the

piezoresistors

17a and 17b.

Due to such an arrangement, in the sensor chip 10 having the structure of the present embodiment, when the diaphragm 14 is deformed as pressure is applied, compressive stress is applied to the

piezoresistors

17a and 17b due to the distortion based on the deformation. Tensile stress is applied to the

piezoresistors

17c and 17d. Then, when the midpoint voltage of the Wheatstone bridge circuit formed by the piezoresistors 17a to 17d is changed, the applied pressure can be converted into an electric signal and output.

Further, the recess 16 has a configuration in which the four corners of the sensor chip 10 having a quadrangular shape are removed in a triangular shape so that the upper surface shape of the outer wall surface of the support portion 15 is similar to the recess 13. . For this reason, the octagon formed by the inner wall surface of the support portion 15, that is, the octagon that becomes the diaphragm 14 and the octagon formed by the outer wall surface of the support portion 15 are arranged concentrically, and each of the octagons It arrange | positions so that the wall surfaces which comprise a side may mutually oppose.

The recess 16 is constituted by removing the etching chip halfway through the thickness of the sensor chip 10. The recess 16 is formed so that the outer shape of the support portion 15 in the sensor chip 10 is an octagon. Therefore, instead of the recess 16, the entire thickness of the sensor chip 10 is removed. It is also possible. However, for such a configuration, it is necessary to make the outer shape of the sensor chip 10 octagonal not by etching but by dicing or the like, and special dicing equipment such as plasma dicing is required. On the other hand, when the concave portion 16 is used, a simple dicing facility is not required because the etching is sufficient, and the concave portion 13 is formed using the etching equipment used when forming the concave portion 13 for forming the diaphragm 14. 16 can be formed. In addition, dicing equipment generally used conventionally can be used for dicing.

Furthermore, by forming the recess 16, the sensor chip 10 can be kept in a square shape on the surface 11 side of the recess 16. For this reason, it is possible to maintain chip rigidity during wire bonding or the like. Further, by keeping the sensor chip 10 in a square shape on the surface 11 side, the sensor chip 10 can be held without reducing the holding portion when die mounting is performed when the sensor chip 10 is bonded to the wiring board 20 as described later. Is possible.

The depths of the recess 13 and the recess 16 may be equal, but here, the depth of the recess 16 is made shallower than that of the recess 13 so that the outer edge of the sensor chip 10 is thicker than the diaphragm 14. It is trying to become. As a result, it is possible to ensure durability against chipping of the outer edge portion of the sensor chip 10 while making the diaphragm 14 have an appropriate thickness.

Further, the surface 11 of the sensor chip 10 is covered and protected by a protective film 18. The protective film 18 is made of an insulating film having an electrical insulating property such as polyimide resin or silicon nitride film (SiN).

The sensor chip 10 thus configured functions as a sensor portion of the semiconductor diaphragm type pressure sensor S1. That is, when pressure is applied, the sensor chip 10 outputs an electrical signal corresponding to the applied pressure due to the piezoresistive effect of the piezoresistor 17. More specifically, when the diaphragm 14 receives pressure from the diaphragm 14 and the diaphragm 14 is distorted by the pressure, the resistance value of the piezoresistor 17 formed on the diaphragm 14 changes, and the piezoresistors 17a to 17d constitute the Wheatstone bridge circuit. The point voltage changes. As a result, the sensor chip 10 can output an electrical signal corresponding to the applied pressure, that is, the applied pressure can be converted into an electrical signal and output.

Further, in the present embodiment, the sensor chip 10 has the support portion 15 bonded to the wiring substrate 20 on the back surface 12 side. Here, the support portion 15 on the back surface 12 of the sensor chip 10 is bonded to the wiring substrate 20 via an adhesive 30. Conventionally, the sensor chip 10 is attached to a glass pedestal, and the sensor chip 10 is bonded to the wiring board 20 via the glass pedestal. Here, the sensor chip 10 is directly attached to the wiring board 20. It has a joined structure. Examples of the adhesive 30 include those made of, for example, silicone rubber, epoxy resin, or the like. Thus, by constituting the adhesive 30 with a low elasticity, it is possible to reduce the stress applied to the sensor chip 10.

More specifically, as shown in FIG. 1, the adhesive 30 has an opening 30 a that is slightly larger than the diaphragm 14 and has an octagonal shape corresponding to the shape of the diaphragm 14, and the outer shape is also octagonal. Yes. In the present embodiment, each side of the opening 30 a and each side of the octagon formed by the outer shape of the adhesive 30 are parallel to each side of the diaphragm 14. The sensor chip 10 is connected to the wiring board 20 in an octagonal region where the adhesive 30 is disposed.

The wiring board 20 is made of, for example, a ceramic board made of ceramic such as alumina, or a resin board such as a printed board. The sensor chip 10 and the wiring board 20 are electrically connected by a bonding wire or the like (not shown), and the output of the Wheatstone bridge circuit is transmitted to the wiring board 20. Although not shown here, the wiring board 20 is also provided with other circuit elements such as a chip capacitor constituting the signal processing circuit, and the output of the Wheatstone bridge circuit is appropriately subjected to signal processing and then externally provided. Can be output to.

In addition, a resin case 40 is provided on the surface of the wiring board 20 opposite to the sensor chip 10, that is, below the wiring board 20 in FIG. 2, and the resin case 40 and the wiring board 20 are connected via an adhesive 31. Are fixed by being joined together. As the adhesive 31, the same silicone rubber as that of the adhesive 30 can be used.

The resin case 40 is attached to, for example, a hose of an exhaust pipe and has a pressure introduction passage 41 for introducing a pressure to be measured. Similarly, the wiring board 20 is provided with a pressure introduction hole 21 for introducing pressure from the back surface 12 side of the sensor chip 10 to the diaphragm 14. The pressure introduction hole 21 communicates with the pressure introduction passage 41 of the resin case 40, and the diaphragm 14 passes through the pressure introduction passage 41 and the pressure introduction hole 21 from the back surface 12 side of the sensor chip 10 as shown in FIG. In addition, a pressure medium to be measured for pressure is introduced.

Further, as shown in FIGS. 3A and 3B, the sensor chip 10 is sealed with a sealing gel 50 from the back surface 12 side to the wiring substrate 20. By performing sealing with the sealing gel 50 in this way, it is not necessary to directly touch the pressure medium measured by the adhesive 30 or the sensor chip 10. As the sealing gel 50, for example, a gel material such as silicone gel, fluorine gel, or fluorosilicone gel can be used.

In addition, conventionally, since the sensor chip 10 is bonded to the wiring substrate 20 via the pedestal, the height of the sealing gel 50 is increased by the thickness of the pedestal, and stress increase due to the sealing gel 50 occurs. An increase in the amount of gel was incurred. On the other hand, since the sensor chip 10 is directly joined to the wiring board 20 without the pedestal as in the present embodiment, the height of the sealing gel 50 can be reduced, and the stress caused by the sealing gel 50 can be reduced. Can be reduced, and the amount of gel can also be reduced.

Here, for example, the front surface 11 side of the sensor chip 10 is, for example, atmospheric pressure, and the pressure medium to be measured for pressure is, for example, exhaust gas, and the pressure applied to the back surface 12 side of the diaphragm 14 is exhaust gas. Pressure.

Then, when the pressure of the pressure medium is introduced into the diaphragm 14, the diaphragm 14 is distorted due to the differential pressure between the front surface 11 and the back surface 12 of the diaphragm 14. Then, an electrical signal corresponding to the pressure of the applied pressure medium is output from the sensor chip 10 by the piezoresistive effect based on the distortion of the diaphragm 14.

In the case of such a configuration, the pressure sensor S1 is a relative pressure type sensor. That is, the pressure sensor S1 has a relative relationship in which the diaphragm 14 is distorted by a differential pressure between the pressure applied to the diaphragm 14 from the front surface 11 side of the sensor chip 10 and the pressure applied to the diaphragm 14 from the back surface 12 side of the sensor chip 10. It becomes a pressure type sensor.

As described above, the pressure sensor S1 according to the present embodiment is configured. In the pressure sensor S1 configured as described above, when the pressure of the pressure medium is applied to the diaphragm 14 through the pressure introduction passage 41 and the pressure introduction hole 21, the diaphragm 14 is applied to the pressure applied to the front surface 11 side and the back surface 12 side. Distortion is based on the pressure difference from the pressure of the applied pressure medium. Due to this distortion, the resistance values of the piezo resistors 17a to 17d change. Therefore, when a DC constant voltage is applied to the input terminal of the Wheatstone bridge circuit formed by the piezoresistors 17a to 17d, the midpoint voltage of the Wheatstone bridge circuit changes due to the change in the resistance value of the piezoresistors 17a to 17d. Based on this, an electric signal corresponding to the pressure of the pressure medium can be obtained as an output.

In such a pressure sensor S1, as described above, the shape of the outer wall surface of the support portion 15 is an octagonal shape.

Thus, by making the shape of the outer wall surface of the support portion 15 an octagonal shape, compared with the case where the outer shape of the sensor chip 10 is left without forming the concave portion 16, thermal stress and Mounting stress can be dispersed. For this reason, it becomes possible to suppress the influence of the zero point offset on the thermal stress and the mounting stress.

Furthermore, in this embodiment, the shape of the upper surface of the inner wall surface of the support portion 15, that is, the shape of the diaphragm 14 constituted by the concave portion 13 is an octagonal shape. Thus, when the upper surface shape of the inner wall surface of the support portion 15 is an octagonal shape, it is possible to increase the amount of distortion of the diaphragm 14 with respect to the pressure application as compared with the circular shape, and the sensitivity of the pressure sensor S1. Can be improved. The reason for this will be described below.

The shape of the inner wall surface of the support 15 is one of the parameters that determine the amount of distortion of the diaphragm 14. The amount of distortion of the diaphragm 14 is determined by the difficulty of deformation based on the shape of the inner wall surface of the support portion 15. This difficulty of deformation is expressed as an amount indicating the difficulty of deformation of the beam member with respect to the cross-sectional secondary moment, that is, the bending moment. Alternatively, it can be expressed as a section modulus that is a value obtained by dividing the sectional moment of inertia by the distance from the inner wall surface of the support portion 15 to the central axis of the diaphragm 14. When the amount of strain of the diaphragm 14 is calculated based on the sectional moment of inertia or the section modulus, when the shape of the inner wall surface of the support portion 15 is a circular shape, the amount of strain of the diaphragm 14 is compared with a polygonal shape. Was reduced and the sensitivity was confirmed to decrease. For example, compared with the case where the shape of the inner wall surface of the support portion 15 is a quadrilateral shape, the sensitivity is 0.73 times higher when the shape is circular.

If the chip size of the sensor chip 10 is increased, even if the inner wall surface of the support portion 15 is circular, it is possible to obtain the same sensitivity as when it is polygonal. However, it is necessary to design the sensitivity in consideration of the trade-off between the suppression of the influence on the offset of the zero point with respect to the thermal stress and the mounting stress and the sensitivity improvement based on the limitation of the chip size. For this reason, the inner wall surface of the support portion 15 is formed in a polygonal shape, in this case, an octagonal shape, so that an improvement in sensitivity can be realized even if there is a restriction on the chip size. Furthermore, if the piezoresistors 17a to 17d having a finite size are not protruded from the diaphragm 14, for example, the side gauge is arranged on the outer edge side of the diaphragm 14 as much as possible, the sensitivity can be further improved. It becomes possible.

Such a pressure sensor S1 is formed by, for example, laminating and bonding the wiring board 20 and the sensor chip 10 on the resin case 40 in order via the

adhesives

30 and 31, and connecting the sensor chip 10 and the wiring board 20 to the wire. Manufactured by electrical connection by bonding or the like. Of course, the order of lamination and joining of each member is arbitrary, and may be changed as appropriate.

(Second Embodiment)
A second embodiment will be described. In the present embodiment, the shape of the concave portion 16 is changed with respect to the first embodiment, and the others are the same as those in the first embodiment. Therefore, only the portions different from the first embodiment will be described. The pressure sensor S1 according to the present embodiment will be described with reference to FIGS. FIG. 4 is a layout diagram corresponding to the IV-IV sectional view of FIG. Although FIG. 5 is not a cross-sectional view, hatching is shown for convenience in order to make the drawing easy to see.

As shown in FIGS. 4 to 6, in this embodiment, each recess 16 is formed in a line shape. Specifically, the outer wall surface of the support portion 15 has an octagonal shape as in the first embodiment, but each recess 16 has a line shape along one side of the outer wall surface of the support portion 15. The thicker portion of the sensor chip 10 is left on the side farther from the center of the sensor chip 10 than the recess 16.

Also, the adhesive 30 is in a state of being disposed not only at the opening 30a surrounding the diaphragm 14 and the outer shape of the octagonal portion but also at the portions corresponding to the four corners of the sensor chip 10.

Thus, even if the concave portion 16 is formed in a line shape, the support portion 15 formed inside thereof can be formed in a polygonal shape. For this reason, also in the pressure sensor S1 of the structure of this embodiment, the same effect as 1st Embodiment can be acquired.

Note that the pressure sensor S1 having such a structure is basically the same as that of the first embodiment, and it is only necessary to change the mask when the recess 16 is formed by etching. Moreover, although each recessed part 16 is comprised in the shape of one line here, it can also be comprised in the shape of a plurality of parallel lines.

(Third embodiment)
A third embodiment will be described. In the present embodiment, the upper surface shape of the outer wall surface of the support portion 15 is changed with respect to the first embodiment, and the other parts are the same as those in the first embodiment. Therefore, only the parts different from the first embodiment are described. explain. The pressure sensor S1 according to the present embodiment will be described with reference to FIGS. 7 is a layout diagram corresponding to the VII-VII cross-sectional view of FIG. Although FIG. 8 is not a cross-sectional view, hatching is shown for convenience in order to make the drawing easy to see.

As shown in FIGS. 7 to 9, in this embodiment, the upper surface shape of the inner wall surface of the support portion 15 remains polygonal, while the upper surface shape of the outer wall surface of the support portion 15 is circular. Moreover, the part which comprises the outer wall surface of the support part 15 among each recessed part 16 is made into circular arc shape so that the upper surface shape of the outer wall surface of the support part 15 may become circular shape.

As for the adhesive 30, the opening 30a surrounding the diaphragm 14 is an octagon, and the outer shape is a circle.

Thus, even if the upper surface shape of the outer wall surface of the support portion 15 is circular, it is possible to suppress the influence of the zero point offset on the thermal stress and the mounting stress. Even in this case, the sensitivity of the pressure sensor S1 can be improved by making the shape of the upper surface of the inner wall surface of the support portion 15, that is, the shape of the diaphragm 14, a polygonal shape.

Note that the pressure sensor S1 having such a structure is basically the same as that of the first embodiment, and it is only necessary to change the mask when the recess 16 is formed by etching.

(Fourth embodiment)
A fourth embodiment will be described. In this embodiment, the upper surface shape of the outer wall surface of the support portion 15 is changed with respect to the first embodiment, and the other parts are the same as those in the first embodiment. Therefore, only the parts different from the first embodiment are described. explain. The pressure sensor S1 according to the present embodiment will be described with reference to FIGS. 10 is a layout diagram corresponding to the II cross-sectional view of FIG. Although FIG. 11 is not a cross-sectional view, hatching is shown for convenience in order to make the drawing easy to see.

As shown in FIGS. 10 and 11, also in the present embodiment, the upper surface shapes of the inner wall surface and the outer wall surface of the support portion 15 are both polygonal shapes, specifically, octagonal shapes. However, the polygon which the upper surface shape of an outer wall surface comprises is shifted and formed in the circumferential direction with respect to the polygon which the upper surface shape of the inner wall surface of the support part 15 comprises.

Specifically, with respect to the inner wall surface of the support portion 15, the four sides of the octagonal shape formed by the upper surface shape of the inner wall surface of the support portion 15 with respect to the four sides of the sensor chip 10 that are formed into a square shape. Each is parallel. Further, the remaining four sides of the octagonal shape formed by the upper surface shape of the inner wall surface of the support portion 15 are parallel to the diagonal lines of the sensor chip 10 that are square.

On the other hand, with respect to the outer wall surface of the support portion 15, the octagon shape formed by the outer wall surface is a predetermined angle with respect to the octagon shape formed by the inner wall surface of the support portion 15 as the rotation axis, for example, 45 °. The state is shifted.

As for the adhesive 30, each side of the opening 30 a surrounding the diaphragm 14 is parallel to each side of the diaphragm 14. The octagon that forms the outer shape of the adhesive 30 is shifted from the sides of the diaphragm 14 by a predetermined angle with the center of the sensor chip 10 as the rotation axis.

In this way, the polygonal shape formed by the inner wall surface and the outer wall surface of the support portion 15 can be a layout in which the angle is shifted with the center of the sensor chip 10 as the rotation axis. Even with such a configuration, it is possible to suppress the influence of the offset of the zero point on the thermal stress and mounting stress, and it is possible to improve the sensitivity of the pressure sensor S1.

(Fifth embodiment)
A fifth embodiment will be described. In the present embodiment, the configuration of the outer wall surface of the support portion 15 is changed with respect to the first, third, and fourth embodiments, and the rest is the same as the first, third, and fourth embodiments. Therefore, only different portions from the first, third, and fourth embodiments will be described. The pressure sensor S1 according to the present embodiment will be described with reference to FIGS. 12 is a layout diagram corresponding to the XII-XII cross-sectional view of FIG. Although FIG. 13 is not a cross-sectional view, hatching is shown for convenience in order to make the drawing easy to see. Moreover, in the following description, the case where the outer wall surface of the support portion 15 is circular as in the third embodiment will be described as an example. However, in the case where the outer wall surface is a polygon as in the first and fourth embodiments. But a similar structure can be applied.

As shown in FIGS. 12 to 14, in this embodiment, the upper surface shape of the inner wall surface of the support portion 15 remains polygonal, while the upper surface shape of the outer wall surface of the support portion 15 is circular. As shown in FIGS. 12 and 13, the outer wall surface of the support portion 15 becomes a tapered inclined surface by forming the recess 16 by isotropic etching or the like.

As described above, even if the outer wall surface of the support portion 15 is an inclined surface, it is possible to suppress the influence of the zero point offset on the thermal stress and the mounting stress by making the upper surface shape circular or polygonal. And the sensitivity of pressure sensor S1 can be improved by making the upper surface shape of the inner wall surface of the support part 15, ie, the shape of the diaphragm 14, into a polygonal shape.

The pressure sensor S1 having such a structure is also basically the same as that of the first embodiment, and the recess 16 is formed by isotropic etching, so that the outer wall surface of the support portion 15 is merely an inclined surface. Good.

(Sixth embodiment)
A sixth embodiment will be described. In the present embodiment, the configuration of the sensor chip 10 is changed with respect to the first to fourth embodiments, and the other parts are the same as those of the first to fourth embodiments. Therefore, the first to fourth embodiments are the same. Only different parts will be described. The pressure sensor S1 according to the present embodiment will be described with reference to FIGS. 15 is a layout diagram corresponding to the XV-XV sectional view of FIG. Although FIG. 16 is not a cross-sectional view, hatching is shown for convenience in order to make the drawing easy to see. In the following description, the case where the outer shapes of the opening 30a and the adhesive 30 are octagonal so as to surround the diaphragm 14 as in the first embodiment will be described as an example. Even in the case of the shape of the fourth embodiment, the same structure can be applied and the same effect can be obtained.

As shown in FIGS. 15 to 17, the sensor chip 10 has a recess 13 for forming the diaphragm 14, but the recess 16 that is a part of the surrounding support portion 15 is formed. Absent. However, the adhesive 30 has an octagonal opening 30a surrounding the diaphragm 14 and an outer shape of the octagon, as in the first embodiment.

That is, the recess 16 is not formed for the sensor chip 10, but the adhesive 30 has the same shape as that of the first embodiment, and non-formation areas where the adhesive 30 is not formed at the four corners of the sensor chip 10 are configured. is doing. Thereby, the part adhere | attached with the adhesive agent 30 among the back surfaces 12 of the sensor chip 10 is made to become the shape similar to 1st Embodiment.

Thus, in the present embodiment, the sensor chip 10 is not formed with the recesses 16 and the outer shape of the adhesive 30 is an octagon, so that the shape of the outer wall surface of the support portion 15 is substantially an octagon. It is the same as the case. For this reason, it is possible to disperse the thermal stress and the mounting stress as compared with the case where the outer shape of the sensor chip 10 remains a square shape and the outer shape of the adhesive 30 remains a square shape. Therefore, it is possible to suppress the influence of the zero point offset on the thermal stress and the mounting stress.

As described above, the outer shape of the adhesive 30 may be different from that of the sensor chip 10, and the substantial shape of the outer wall surface of the sensor chip 10 may be defined by the shape of the adhesive 30. In this case, as described herein, the outer shape of the adhesive 30 may be the same shape as the inner wall surface of the support portion 15, that is, a polygon more than a quadrangle, or the second to fourth embodiments. As described above, the shape of the inner wall surface of the support portion 15 may be different. For example, the shape of the inner wall surface of the support portion 15 may be a polygon that is equal to or greater than a quadrangle, and the outer shape of the adhesive 30 may be a circle or may be a polygon that is different from the shape of the inner wall surface of the support portion 15. .

(Other embodiments)
Although the present disclosure has been described based on the above-described embodiment, the present disclosure is not limited to the embodiment, and includes various modifications and modifications within an equivalent range. In addition, various combinations and forms, as well as other combinations and forms including only one element, more or less, are within the scope and spirit of the present disclosure.

For example, in the above-described embodiment, an octagon has been described as an example of a polygon formed by the inner wall surface of the support portion 15, that is, a polygon formed by the diaphragm 14 or a polygon formed by the outer wall surface of the support portion 15. However, this is merely an example, and other polygons such as a hexagon, a decagon, and a dodecagon may be used as long as the polygon is a quadrangle or more. However, when a Wheatstone bridge circuit including piezoresistors 17a to 17d is formed on the diaphragm 14, it is preferable that the side gauges and the center gauges of the piezoresistors 17a to 17d are arranged symmetrically in the diaphragm 14. Therefore, it is preferable to use a polygonal shape with even angles.

In the first embodiment, the pressure introduction hole 21 is provided in the wiring substrate 20 to realize the back pressure receiving pressure sensor S1. However, the diaphragm 14 receives the measurement pressure from the front surface 11 of the sensor chip 10. It may be a surface pressure-receiving type. In that case, the wiring board 20 may not have the pressure introducing hole 21.

Further, the joining member to which the back surface 12 side of the sensor chip 10 is joined is not limited to the wiring substrate 20 described above, and various members such as a lead frame and a resin member are applicable.

Further, in each of the above embodiments, the adhesive 30 does not have to be composed of a material such as silicone rubber or epoxy resin. For example, as shown in FIG. 18, the adhesive 30 may contain a granular member 30 b such as a bead for maintaining the thickness, that is, the height of the adhesive 30. When such a granular member 30b is contained in the adhesive 30 and the height of the adhesive 30 is increased, it is possible to suppress the force due to expansion and contraction of a resin having a large linear expansion coefficient from being transmitted to the sensor chip 10. For this reason, it becomes possible to improve the pressure measurement accuracy by the sensor chip 10. As such a granular member 30b, it is preferable to use a low elastic material such as a polymer such as a silicone rubber or an epoxy resin that constitutes the adhesive 30.

Further, the pressure sensor is not limited to the one that detects the exhaust pressure described above, but is used for pressure detection of various applications such as atmospheric pressure, engine intake pressure, and various equipment and container pressure. be able to.

Claims

A pressure sensor that outputs an electrical signal corresponding to an applied pressure,
A chip made of a semiconductor having a rectangular plate shape, and a first recess (13) is formed on the back surface (12), and a thin portion on the front surface (11) side corresponding to the first recess is a diaphragm (14). And a sensor chip (10) having a piezoresistance (17) on the surface, the periphery of the first recess being a support portion (15),
A bonding member (20) bonded to the support portion on the back surface of the sensor chip,
A second recess (16) is formed on the back surface of the sensor chip, and an upper surface shape of the outer wall surface of the support portion is a polygonal shape equal to or greater than a quadrangle, and the inside of the support portion constituting the shape of the diaphragm A pressure sensor in which the shape of the upper surface of the wall surface is a polygonal shape greater than or equal to a square.
A pressure sensor that outputs an electrical signal corresponding to an applied pressure,
A chip made of a semiconductor having a rectangular plate shape, and a first recess (13) is formed on the back surface (12), and a thin portion on the front surface (11) side corresponding to the first recess is a diaphragm (14). And a sensor chip (10) having a piezoresistance (17) on the surface, the periphery of the first recess being a support portion (15),
A bonding member (20) bonded to the support portion on the back surface of the sensor chip,
Second recesses (16) are formed at the four corners of the back surface of the sensor chip, and the top surface shape of the outer wall surface of the support portion is circular, and the inner wall surface of the support portion constituting the shape of the diaphragm A pressure sensor in which the top surface shape is a polygonal shape greater than or equal to a quadrangle.
The pressure sensor according to claim 1 or 2, wherein an upper surface shape of an inner wall surface of the support portion is an octagonal shape.
The upper surface shape of the outer wall surface of the support portion is an octagonal shape, the upper surface shape of the inner wall surface of the support portion is an octagonal shape, and each octagon shape formed by the outer wall surface and the inner wall surface of the support portion is concentric. The pressure sensor according to claim 1, wherein the wall surfaces constituting each side of each octagonal shape formed by the outer wall surface and the inner wall surface of the support portion are arranged to face each other.
The upper surface shape of the outer wall surface of the support portion is an octagonal shape, the upper surface shape of the inner wall surface of the support portion is an octagonal shape, and each octagon shape formed by the outer wall surface and the inner wall surface of the support portion is concentric. And the octagon shape formed by the outer wall surface of the support portion is shifted by a predetermined angle with the center of the diaphragm as the rotation axis, with respect to the octagon shape formed by the inner wall surface of the support portion. The pressure sensor according to claim 1.
The pressure sensor according to any one of claims 1 to 5, wherein an outer wall surface of the support portion is a tapered inclined surface.
The bonding member is a wiring board (20) provided with a hole (21) for introducing pressure to the diaphragm from the back side of the sensor chip,
The support portion on the back surface of the sensor chip is bonded to the wiring board via an adhesive (30),
The pressure sensor according to any one of claims 1 to 6, wherein the first recess is filled with a sealing gel (50).
A pressure sensor that outputs an electrical signal corresponding to an applied pressure,
A chip made of a semiconductor having a rectangular plate shape, and a first recess (13) is formed on the back surface (12), and a thin portion on the front surface (11) side corresponding to the first recess is a diaphragm (14). And a sensor chip (10) having a piezoresistance (17) on the surface, the periphery of the first recess being a support portion (15),
A bonding member (20) bonded to the support portion on the back surface of the sensor chip;
An adhesive (30) that is disposed between the sensor chip and the joining member and joins the support portion and the joining member;
The upper surface shape of the inner wall surface of the support part that constitutes the shape of the diaphragm is a polygonal shape of a quadrangle or more,
The adhesive is provided with non-formation regions where the adhesive is not formed at the four corners of the sensor chip, so that the outer shape viewed from the surface side of the sensor chip is a polygonal or circular shape of a quadrangle or more. Pressure sensor.
The pressure sensor according to claim 7 or 8, wherein the adhesive contains a granular member (30b) that maintains the thickness of the adhesive.