JP2018205263A - Pressure sensor - Google Patents

Abstract

To increase the connection property of connecting a sensor chip with a diaphragm and a supporting member supporting the sensor chip to each other.SOLUTION: A pressure sensor 1 includes a sensor chip 2, a supporting member 3, and a connection layer 4. The sensor chip 2 includes a diaphragm 25 and a thick part 26 around the diaphragm 25. The supporting member 3 has a chip containing recess 34 formed by a bottom surface 35, which faces the bottom surface 22 of the sensor chip, and a wall surface 36, which faces an end surface 23 of the sensor chip 2. Arranging the sensor chip 2 to be contained in the chip containing recess 34 enables the sensor chip 2 to be supported. A first connection layer 4 connects the sensor chip 2 and the supporting member 3 together by being filled in between the back surface 22 of the sensor chip 2 corresponding to the thick part 26 and the bottom surface 35 of the chip containing recess 34 and between the end surface 23 of the sensor chip 2 and the wall surface 36 of the chip containing recess 34.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a pressure sensor.

  The pressure sensor disclosed in Patent Document 1 is formed by bonding a sensor chip having a diaphragm to a wiring board. Specifically, the wiring board is bonded to a thick part around the diaphragm in the sensor chip via an adhesive. This pressure sensor outputs the distortion of the diaphragm due to the introduced pressure as a signal due to the piezoresistance effect.

JP 2017-62193 A

  In this type of pressure sensor, the bonding state at the bonding portion between the support member such as the wiring board and the sensor chip is important for maintaining good performance in the pressure sensor. That is, for example, it is necessary to prevent peeling at the joint due to application of pressure. Alternatively, it is necessary to prevent leakage of the fluid that is a pressure measurement target at the joint. In this regard, when the sensor chip is downsized, the area of the joint portion is reduced, and there is a concern that peeling or the like occurs.

  The present invention has been made in view of the circumstances exemplified above. That is, an object of the present invention is to improve the bondability between a sensor chip having a diaphragm and a support member that supports the sensor chip.

The pressure sensor (1) according to claim 1 is configured to generate an output corresponding to the pressure of the fluid to be measured.
This pressure sensor
A plate-like member having a front surface (21) and a back surface (22) parallel to each other, an end surface (23) intersecting the front surface and the back surface, and a first recess (24) provided on the back surface side. A diaphragm (25) formed in a thin plate shape at a position corresponding to the first recess, and a thick part (26) provided around the diaphragm and coupled to the outer edge of the diaphragm. Sensor chip (2),
A second recess (34) formed by a bottom surface (35) provided to face the back surface and a wall surface (36) provided to face the end surface; A support member (3) provided to support the sensor chip by accommodating the sensor chip;
By filling between the back surface of the sensor chip corresponding to the thick part and the bottom surface of the second recess, and between the end surface of the sensor chip and the wall surface of the second recess. A bonding layer (4) provided to bond the sensor chip and the support member;
It has.

  In this configuration, the sensor chip is bonded to the support member via the bonding layer in a state of being accommodated in the second recess provided in the support member. Specifically, the back surface of the thick portion of the sensor chip is bonded to the bottom surface of the second recess of the support member via the bonding layer. Further, the end surface of the sensor chip is bonded to the wall surface of the second recess of the support member via the bonding layer. That is, the sensor chip is joined to the support member at the back surface and the end surface. Therefore, according to this configuration, it is possible to improve the bondability between the sensor chip having the diaphragm and the support member that supports the sensor chip as compared with the related art.

  Note that the reference numerals in parentheses attached to each means in the above and claims column indicate an example of the correspondence between the means and specific means described in the embodiments described later. Therefore, the technical scope of the present invention is not limited at all by the description of the above reference numerals.

It is a sectional side view showing the schematic structure of the pressure sensor concerning one embodiment of the present invention. It is a sectional side view which shows the structure of the modification of the pressure sensor shown by FIG. FIG. 3 is a bottom view showing an example of forming a bonding recess shown in FIG. 2. It is a bottom view which shows another example of formation of the recessed part for joining shown by FIG. It is a bottom view which shows another example of formation of the recessed part for joining shown by FIG. It is a sectional side view which shows the structure of the other modification of the pressure sensor shown by FIG. It is a sectional side view which shows the structure of another modification of the pressure sensor shown by FIG.

(Embodiment)
Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that various modifications applicable to the embodiment may interfere with understanding of the embodiment if inserted in the middle of a series of descriptions regarding the embodiment. This will be described later.

(Constitution)
Referring to FIG. 1, a pressure sensor 1 according to an embodiment of the present invention is configured to generate an output (for example, a voltage) corresponding to the pressure of a fluid that is a pressure measurement target introduced into a fluid introduction space S. ing. The fluid that is the object of pressure measurement is, for example, air, EGR gas, exhaust gas, or the like. EGR is an abbreviation for Exhaust Gas Recirculation.

  Hereinafter, the structure of each part which is a component of the pressure sensor 1 is demonstrated. For convenience of explanation, a right-handed XYZ orthogonal coordinate system is set as shown in each figure. In this case, a direction parallel to the Z axis in the figure is referred to as an “axial direction”, and an arbitrary direction orthogonal to the Z axis is referred to as a “creeping direction”. That is, the creeping direction is a direction parallel to the XY plane. Further, viewing the object in the negative Z-axis direction in the figure is referred to as “plan view”, and viewing the object in the positive Z-axis direction in the figure is referred to as “bottom view”.

  The pressure sensor 1 includes a sensor chip 2, a support member 3, a first bonding layer 4, a case member 5, a second bonding layer 6, and a back surface gel 7.

  The sensor chip 2 is a plate-like member having a thickness direction parallel to the axial direction, and is formed in a substantially rectangular shape in plan view. That is, the sensor chip 2 has a front surface 21 and a back surface 22 that extend in the creeping direction and are parallel to each other. In addition, the sensor chip 2 has an end surface 23 that intersects the front surface 21 and the back surface 22. Specifically, in the present embodiment, the end surface 23 is formed to be orthogonal to the front surface 21 and the back surface 22.

  A diaphragm forming recess 24 is provided on the back surface 22 side of the sensor chip 2. The diaphragm forming recess 24 is a recess provided in the central portion in the creeping direction of the sensor chip 2 and is formed so as to open along the axial direction. That is, a cylindrical or prismatic space is formed inside the diaphragm forming recess 24.

  The sensor chip 2 has a diaphragm 25 and a thick portion 26. The diaphragm 25 is a thin part provided at a position corresponding to the diaphragm forming recess 24 and is formed in a thin plate shape. In the present embodiment, the diaphragm 25 is formed flush with the surface 21. The thick part 26 is provided around the diaphragm 25. That is, the thick portion 26 is coupled to the outer edge portion of the diaphragm 25 so as to support the diaphragm 25.

  The sensor chip 2 is a so-called silicon-based semiconductor substrate, and has various circuit patterns on the surface 21 side. In particular, the diaphragm 25 has a gauge resistance (not shown).

  The support member 3 is a member that supports the sensor chip 2 and is bonded to the sensor chip 2 via the first bonding layer 4. Specifically, the support member 3 is a ceramic substrate made of alumina or the like, and has an upper surface 31 exposed in the positive direction of the Z axis in the drawing and a lower surface 32 on the back side thereof.

  Various circuit patterns and the like are formed on the upper surface 31. That is, the circuit pattern or the like provided on the sensor chip 2 and the circuit pattern or the like provided on the support member 3 are electrically connected by wire bonding or the like.

  The lower surface 32 is bonded to the case member 5 via the second bonding layer 6. Further, a communication hole 33 is formed from the lower surface 32 side toward the diaphragm forming recess 24. The communication hole 33 is a through hole penetrating the support member 3 in the axial direction, and is formed so that the opening diameter increases as the distance from the sensor chip 2 increases.

  The support member 3 is formed with a chip receiving recess 34. The chip accommodating recess 34 is a recess that opens in the positive direction of the Z-axis in the drawing, and is provided on the upper surface 31 side. The chip housing recess 34 is formed to house the sensor chip 2. That is, the chip receiving recess 34 has a shape corresponding to the outer shape of the sensor chip 2 in plan view.

  Specifically, the chip receiving recess 34 has a bottom surface 35 extending in the creeping direction and a wall surface 36 extending in the axial direction. The bottom surface 35 is provided so as to face the back surface 22 of the sensor chip 2 at a position corresponding to the thick portion 26. The wall surface 36 provided on the inner surface of the square tube is formed to face the end surface 23 of the sensor chip 2 with a minute gap, for example, a gap of about 75 μm.

  The first bonding layer 4 is provided so as to bond the sensor chip 2 and the support member 3. Specifically, in the present embodiment, the first bonding layer 4 is filled between the back surface 22 of the sensor chip 2 corresponding to the thick portion 26 and the bottom surface 35 of the chip housing recess 34. The first bonding layer 4 is filled between the end surface 23 of the sensor chip 2 and the wall surface 36 of the chip housing recess 34. The first bonding layer 4 is a film made of silicone resin or the like and having a thickness of about 75 μm, and is formed by curing an adhesive.

  The case member 5 is a synthetic resin member and is provided so as to support the support member 3. Specifically, the case member 5 and the support member 3 are bonded via the second bonding layer 6. The second bonding layer 6 is a film made of silicone resin or the like and having a thickness of about 100 μm, and is formed by curing an adhesive.

  The case member 5 is formed with a substrate housing recess 51 and a fluid introduction hole 52. The substrate housing recess 51 is a recess that opens in the positive direction of the Z-axis in the figure, and is formed so as to accommodate the support member 3. The fluid introduction hole 52 is a through hole that penetrates the case member 5 in the axial direction, and is provided so as to communicate with the communication hole 33. That is, the fluid introduction space S is formed by the communication hole 33 and the fluid introduction hole 52.

  The back surface gel 7 is a gel material such as silicone, fluorine, or fluorosilicone, and is filled in the entire diaphragm forming recess 24 and a portion adjacent to the chip receiving recess 34 in the communication hole 33. The back surface gel 7 is provided so as to protect the sensor chip 2 from icing and cracking due to moisture entering the fluid introduction space S, and to prevent deterioration of the adhesive due to corrosive substances contained in the fluid and clogging due to wrinkles.

(effect)
Hereinafter, effects produced by the configuration of the present embodiment will be described with reference to the drawings.

  In this type of pressure sensor 1, the bonding state at the bonding portion between the sensor chip 2 and the support member 3 is important for maintaining good performance in the pressure sensor 1. That is, for example, it is necessary to prevent peeling at the joint due to application of pressure. Alternatively, it is necessary to prevent leakage of the fluid that is a pressure measurement target at the joint. In this regard, when the sensor chip 2 is downsized, the area of the joint portion is reduced, and there is a concern that peeling or the like occurs.

  In the present embodiment, the sensor chip 2 is bonded to the support member 3 via the first bonding layer 4 while being housed in the chip housing recess 34 provided in the support member 3. Specifically, the back surface 22 of the thick portion 26 of the sensor chip 2 is bonded to the bottom surface 35 of the chip housing recess 34 of the support member 3 via the first bonding layer 4. Further, the end surface 23 of the sensor chip 2 is bonded to the wall surface 36 of the chip housing recess 34 of the support member 3 via the first bonding layer 4.

  As described above, in the present embodiment, the sensor chip 2 is joined to the support member 3 at the back surface 22 and the end surface 23. Therefore, according to such a configuration, it is possible to improve the bondability between the sensor chip 2 having the diaphragm 25 and the support member 3 that supports the diaphragm 25 as compared with the related art. Specifically, good joint strength and good leak resistance can be realized at the joint between the sensor chip 2 and the support member 3. Even if the sensor chip 2 is downsized and the area of the joint between the sensor chip 2 and the support member 3 is reduced, it is possible to maintain good joint strength and good leak resistance.

(Modification)
The present invention is not limited to the above embodiment. Therefore, it can change suitably with respect to the said embodiment. Hereinafter, typical modifications will be described. In the following description of the modification, differences from the above embodiment will be mainly described. Moreover, in the said embodiment and modification, the same code | symbol is attached | subjected to the part which is mutually the same or equivalent. Therefore, in the following description of the modified example, regarding the components having the same reference numerals as those in the above embodiment, the description in the above embodiment can be appropriately incorporated unless there is a technical contradiction or special additional explanation.

  The fluid whose pressure is to be measured is not limited to gas. That is, the fluid whose pressure is to be measured may be a liquid or a supercritical fluid. Further, the pressure sensor 1 may be an absolute pressure sensor or a relative pressure sensor. The pressure sensor 1 may be a sensor used in a flooded environment, for example, a side collision detection sensor housed in a vehicle door.

  The present invention is not limited to piezoresistive pressure sensors. That is, the present invention can be suitably applied to a pressure sensor of a type (for example, a capacitance type or a piezoelectric type) different from the piezoresistive type.

  The configuration of the sensor chip 2 is not limited to the specific example shown in the embodiment. FIG. 2 shows a configuration of a modification. As shown in FIG. 2, the thick portion 26 in the sensor chip 2 may have a bonding recess 261. The bonding recess 261 is a groove or hole formed in the back surface 22 and is provided so as to open toward the bottom surface 35 of the chip housing recess 34. The bonding recess 261 can be formed by a dry etching method such as Deep RIE. RIE stands for Reactive Ion Etching. The bonding recess 261 is filled with the first bonding layer 4.

  According to such a configuration, the bonding recess 261 is provided in the thick portion 26 of the sensor chip 2, and the sensor chip 2 and the support member 3 are bonded so that the bonding recess 261 is filled with the first bonding layer 4. As a result, the bondability between the sensor chip 2 and the support member 3 can be further improved.

  The shape of the bonding recess 261 in the bottom view is not particularly limited. That is, for example, as shown in FIG. 3, when the diaphragm 25 has a substantially regular octagonal shape in bottom view, the bonding recess 261 is provided so as to surround the periphery of the diaphragm 25 in bottom view. It may be a substantially regular octagonal groove. Or as FIG. 4 shows, the recessed part 261 for joining may be a substantially rectangular-shaped groove part by bottom view.

  In the case where the bonding concave portion 261 is formed as a groove portion, the groove portion is not exposed to the end surface 23 of the sensor chip 2 and does not communicate with the diaphragm forming concave portion 24 and surrounds the periphery of the diaphragm 25 and is a curved line closed in a bottom view. Or it is suitable to provide in a polygonal line shape. Thereby, good leak resistance can be realized.

  As shown in FIG. 5, the bonding recess 261 may be a prismatic or elliptical column-shaped hole provided so as not to communicate with the diaphragm forming recess 24 around the diaphragm 25. In this case, the number and arrangement of the bonding recesses 261 are not particularly limited.

  As shown in FIG. 6, the sensor chip 2 may have a flange portion 262. The flange portion 262 is provided so as to protrude in the creeping direction along the back surface 22 from the lower end portion including the back surface 22 in the thick portion 26. That is, the flange portion 262 is formed flush with the back surface 22.

  In this configuration, in addition to the same effects as the above embodiment, the following effects can be achieved. That is, a space for accommodating the adhesive constituting the first bonding layer 4 is formed on the upper side of the flange portion 262 (that is, on the Z axis positive direction side in the drawing). Therefore, according to such a configuration, it is possible to satisfactorily suppress the adhesive from creeping up on the surface 21 of the sensor chip 2 and the upper surface 31 of the support member 3, which are surfaces having a wire bonding portion and the like.

  As shown in FIG. 7, the sensor chip 2 may have a protrusion 263. The protruding portion 263 is provided so as to protrude from the protruding end in the creeping direction of the flange portion 262 toward the positive Z-axis direction in the drawing. That is, the projecting portion 263 is formed in a rib shape projecting along the axial direction at the distal end portion of the flange portion 262.

  In the configuration of this modification, the flange end surface 264 that forms the outer peripheral surface of the flange portion 262 is provided so as to face the wall surface 36 of the chip housing recess 34 of the support member 3. That is, the flange end surface 264 is an outer surface facing the wall surface 36 in the protruding portion 263, and is provided so as to constitute a part of the end surface 23 in the sensor chip 2.

  Further, in this modification, a flange recess 265 is formed by a space surrounded by the thick portion 26, the flange portion 262, and the protruding portion 263. The flange recess 265 is a recess that opens in the positive direction of the Z-axis in the drawing, and is provided so as to surround the outer periphery of the thick portion 26 in plan view.

  In such a configuration, the area of the end face 23 in the sensor chip 2 is increased as compared with the configuration of the modified example shown in FIG. Therefore, the bonding strength is improved as compared with the configuration of the modification shown in FIG. Further, the flange recess 265 forms a space that accommodates the adhesive constituting the first bonding layer 4. Therefore, according to such a configuration, it is possible to satisfactorily suppress the adhesive from creeping up on the surface 21 of the sensor chip 2 and the upper surface 31 of the support member 3, which are surfaces having a wire bonding portion and the like.

  As shown in FIG. 1 and the like, the support member 3 can be formed by stacking a plurality of ceramic substrates. Alternatively, the support member 3 can be formed by performing a process such as polishing on a single ceramic substrate.

  The support member 3 is not limited to a ceramic substrate or a semiconductor substrate. That is, for example, the support member 3 may be a so-called printed board made of synthetic resin.

  The case member 5 is not limited to being made of synthetic resin. That is, for example, the case member 5 may be made of metal or ceramics. The second bonding layer 6 can also be filled into a gap between the outer end surface of the support member 3 and the inner wall surface of the substrate housing recess 51.

  The back gel 7 can be omitted.

  In the above description, the plurality of constituent elements that are integrally formed with each other seamlessly may be formed by bonding separate members to each other. Similarly, a plurality of constituent elements formed by sticking separate members to each other may be formed integrally with each other without a seam.

  In the above description, the plurality of constituent elements formed of the same material may be formed of different materials. Similarly, a plurality of constituent elements formed of different materials may be formed of the same material.

  The modification is not limited to the above example. A plurality of modifications may be combined with each other. Furthermore, all or a part of the above embodiment and all or a part of any modification can be combined with each other.

DESCRIPTION OF SYMBOLS 1 Pressure sensor 2 Sensor chip 24 Diaphragm formation recessed part 25 Diaphragm 26 Thick part 3 Support member 34 Chip accommodation recessed part 35 Bottom face 36 Wall surface 4 1st joining layer

Claims (4)

A pressure sensor (1) configured to generate an output corresponding to the pressure of a fluid whose pressure is to be measured,
A plate-like member having a front surface (21) and a back surface (22) parallel to each other, an end surface (23) intersecting the front surface and the back surface, and a first recess (24) provided on the back surface side. A diaphragm (25) formed in a thin plate shape at a position corresponding to the first recess, and a thick part (26) provided around the diaphragm and coupled to the outer edge of the diaphragm. Sensor chip (2),
A second recess (34) formed by a bottom surface (35) provided to face the back surface and a wall surface (36) provided to face the end surface; A support member (3) provided to support the sensor chip by accommodating the sensor chip;
By filling between the back surface of the sensor chip corresponding to the thick part and the bottom surface of the second recess, and between the end surface of the sensor chip and the wall surface of the second recess. A bonding layer (4) provided to bond the sensor chip and the support member;
With pressure sensor. The thick part in the sensor chip has a third recess (261) that opens toward the bottom surface of the second recess.
The pressure sensor according to claim 1. The sensor chip has a flange portion (262) provided so as to protrude in a creeping direction along the back surface from a lower end portion including the back surface in the thick portion.
The pressure sensor according to claim 1 or 2. The sensor chip further includes a projecting portion (263) provided so as to project from the projecting end of the flange portion along the thickness direction from the back surface toward the front surface.
The end surface includes a surface (264) facing the wall surface of the protrusion,
A concave portion (264) that opens in the thickness direction is formed by the thick portion, the flange portion, and the protruding portion.
The pressure sensor according to claim 3.

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