JP7343343B2 - sensor chip - Google Patents

Description

The technology disclosed herein relates to a sensor chip.

Patent Document 1 discloses a sensor chip made of a semiconductor. The sensor chip of Patent Document 1 includes a diaphragm section, a support section that supports the outer peripheral end of the diaphragm section, a plurality of piezoresistive sections disposed on the diaphragm section, and a section below the plurality of piezoresistive sections. and an insulating film extending in a direction along the lower surface of the diaphragm portion. Further, the sensor chip of Patent Document 1 includes a plurality of grooves extending around each of the plurality of piezoresistive sections from the upper surface of the diaphragm section to a position reaching the insulating film. Each groove portion surrounds each piezoresistive portion when viewed in a direction perpendicular to the top surface of the diaphragm portion. The sensor chip disclosed in Patent Document 1 uses a plurality of piezoresistive sections to detect stress in a diaphragm section when pressure is applied to the diaphragm section.

Japanese Patent Application Publication No. 2006-30159

In the sensor chip disclosed in Patent Document 1, each piezoresistive part is insulated from the surroundings by each groove formed around each piezoresistive part. However, in the sensor chip disclosed in Patent Document 1, since each groove surrounds each piezoresistive part, there is a problem in that the stress in the diaphragm part is divided by the groove between the piezoresistive parts. . Therefore, the stress in the diaphragm portion may not be detected with high accuracy.

The present specification provides a technique that can insulate a plurality of piezoresistive parts from the surroundings and detect stress in a diaphragm part with high accuracy.

The sensor chip disclosed in this specification may be a sensor chip made of a semiconductor. The sensor chip includes a diaphragm section that includes a pressure receiving surface that receives fluid pressure, a support section that supports an outer peripheral end of the diaphragm section, and a plurality of piezoresistive sections arranged on the diaphragm section. , an insulating film extending in a direction along the pressure receiving surface on a side closer to the pressure receiving surface than the plurality of piezoresistive parts, and an insulating film extending from a surface opposite to the pressure receiving surface around the plurality of piezoresistive parts. It is a groove part which extends to the position which reaches, Comprising: When it sees in the direction orthogonal to the said pressure receiving surface, the said groove part may be provided with the said groove part which goes around so that the said several said piezoresistive part may be surrounded.

According to this configuration, on the side closer to the pressure receiving surface than the plurality of piezoresistive parts, the plurality of piezoresistive parts can be insulated from the surroundings by the insulating film extending in the direction along the pressure receiving surface. Furthermore, the plurality of piezoresistive parts can be insulated from the surroundings by the groove extending around the plurality of piezoresistive parts from the surface opposite to the pressure receiving surface to the position reaching the insulating film. Further, according to the above configuration, the groove portion goes around the plurality of piezoresistive portions when viewed in a direction perpendicular to the pressure receiving surface. Therefore, while the plurality of piezoresistive sections can be insulated from the surroundings by the grooves, stress in the diaphragm section is not divided between the piezoresistive sections by the grooves. Therefore, stress in the diaphragm portion can be detected with high accuracy.

The groove portion may extend through the insulating film. According to this configuration, insulation can be improved.

The sensor chip may further include an insulating filler filled in the groove. According to this configuration, insulation can be improved.

The sensor chip may be fixed to a container or tube. The sensor chip may be fixed to the inner surface of the container or the tube such that the pressure receiving surface of the diaphragm portion faces inside the container or the tube.

According to this configuration, when the pressure of the fluid inside the container or tube acts on the sensor chip, the sensor chip is pressed against the inner surface of the container or tube, so the sensor chip can be firmly fixed to the container or tube. can.

FIG. 2 is a cross-sectional view of a sensor chip according to an example. FIG. 2 is a top view of a sensor chip according to an example. FIG. 7 is a cross-sectional view of a sensor chip according to another example. FIG. 7 is a cross-sectional view of a sensor chip according to another example. FIG. 7 is a cross-sectional view of a sensor chip according to another example. FIG. 7 is a cross-sectional view of a sensor chip according to another example.

A sensor chip 1 according to an embodiment will be described with reference to the drawings. As shown in FIGS. 1 and 2, the sensor chip 1 according to the embodiment includes a diaphragm section 10, a plurality of (four in this embodiment) piezoresistive sections 20, and a support section 30. Further, the sensor chip 1 includes an insulating film 40 and a groove portion 50. The sensor chip 1 is made of, for example, a semiconductor SOI (Silicon on Insulator) substrate.

The sensor chip 1 is placed inside a container 200 containing a liquid w. The sensor chip 1 is fixed to the inner surface 210 of the upper part 205 of the container 200. An opening 220 is formed in the upper part 205 of the container 200. The sensor chip 1 is arranged such that the diaphragm part 10 faces the opening 220 of the container 200. A container 200 to which the sensor chip 1 is fixed is fixed to a pipe 250 through which liquid w flows. The liquid w flowing inside the tube 250 flows into the inside of the container 200. The pressure of the liquid w inside the container 200 acts on the sensor chip 1. The sensor chip 1 is used to detect the pressure of the liquid w. The liquid w whose pressure is to be detected is, for example, water. Water has conductivity.

The diaphragm portion 10 has a thin film-like configuration made of a semiconductor (for example, Si). The diaphragm portion 10 is formed at the center of the sensor chip 1 in a direction along the top surface of the sensor chip 1 . The diaphragm portion 10 is formed, for example, by etching the SOI substrate down to the insulating film 40. The diaphragm portion 10 includes a pressure receiving surface 14 that receives the pressure of the liquid w inside the container 200. The pressure receiving surface 14 is formed on the lower surface of the diaphragm portion 10. The pressure receiving surface 14 faces the inside of the container 200. The pressure receiving surface 14 faces the opposite side (lower side) from the inner surface 210 of the upper part 205 of the container 200. The pressure receiving surface 14 faces the liquid w inside the container 200. The pressure of the liquid w inside the container 200 acts on the pressure receiving surface 14. The diaphragm portion 10 deforms to bend upward when the pressure receiving surface 14 receives the pressure of the liquid w. The diaphragm portion 10 is formed into a circular shape when viewed from a direction perpendicular to the pressure receiving surface 14 (see FIG. 2). The outer circumferential end 12 of the diaphragm portion 10 is circular. In other embodiments, the diaphragm portion 10 may have a rectangular shape. The shape of the diaphragm portion 10 is not limited.

The plurality of piezoresistive sections 20 are arranged above the diaphragm section 10. The plurality of piezoresistive sections 20 are arranged at intervals from each other. Each piezoresistive section 20 is formed by implanting ions into a semiconductor (for example, Si) constituting the diaphragm section 10. When the diaphragm section 10 is deformed by the pressure of the liquid w inside the container 200, each piezoresistive section 20 is distorted accordingly. When distortion occurs in each piezoresistive section 20, the resistance value of each piezoresistive section 20 changes.

The plurality of piezoresistive sections 20 constitute part of a bridge circuit (not shown) for detecting stress in the diaphragm section 10. Each piezoresistive section 20 corresponds to each resistance element in the bridge circuit. Each piezoresistive section 20 is connected to wiring of a bridge circuit. By detecting the stress in the diaphragm portion 10 based on the bridge circuit, the pressure of the liquid w (liquid w inside the container 200) acting on the pressure receiving surface 14 of the diaphragm portion 10 can be detected. Since the method of detecting stress based on a bridge circuit is well known, a detailed explanation will be omitted.

The support part 30 of the sensor chip 1 is located around the diaphragm part 10. The diaphragm part 10 is arranged inside the support part 30. The support portion 30 is fixed to the outer peripheral end portion 12 of the diaphragm portion 10. The support portion 30 supports the outer peripheral end portion 12 of the diaphragm portion 10. The support portion 30 is integrally formed with the diaphragm portion 10. The support portion 30 is made of a semiconductor (eg, Si). The thickness of the support part 30 in the vertical direction is thicker than the thickness of the diaphragm part 10. The support portion 30 has a thick block-like configuration. The support portion 30 surrounds the entire circumference of the outer peripheral end portion 12 of the diaphragm portion 10 (see FIG. 2). The support portion 30 goes around the outer peripheral end portion 12 of the diaphragm portion 10 . The lower surface and outer peripheral surface of the support portion 30 are in contact with the liquid w inside the container 200.

The support portion 30 includes a fixing surface 32 that is fixed to the inner surface 210 of the upper portion 205 of the container 200 . The fixing surface 32 is formed on the upper surface of the sensor chip 1. The fixed surface 32 faces the opposite side (upper side) of the pressure receiving surface 14 of the diaphragm portion 10. The fixed surface 32 is located above the pressure receiving surface 14. The fixing surface 32 is fixed to the container 200 such that the pressure receiving surface 14 of the diaphragm portion 10 faces the inside of the container 200 and the top surface of the diaphragm portion 10 faces the outside of the container 200. The fixing surface 32 is bonded to the inner surface 210 of the container 200 with an adhesive 60. The adhesive 60 is, for example, silicone. The fixing surface 32 is located on the outer side of the groove portion 50, which will be described later.

The insulating film 40 is, for example, a SiO ₂ film. The insulating film 40 is arranged under the diaphragm part 10. The insulating film 40 is arranged closer to the pressure receiving surface 14 (lower side) than the plurality of piezoresistive parts 20 arranged in the diaphragm part 10 . The insulating film 40 is located between the plurality of piezoresistive parts 20 and the liquid w inside the container 200. The insulating film 40 covers the entire pressure receiving surface 14 of the diaphragm portion 10 . The insulating film 40 extends in a direction along the pressure receiving surface 14. The insulating film 40 extends to the outside of the outer peripheral end portion 12 of the diaphragm portion 10 in the direction along the pressure receiving surface 14 . Further, the insulating film 40 extends from the diaphragm section 10 to the support section 30. The insulating film 40 is arranged inside the support section 30.

The groove portion 50 is formed in the support portion 30. The groove portion 50 extends continuously from the upper surface of the support portion 30 to below the insulating film 40 . The groove portion 50 extends through the insulating film 40. A bottom surface 52 of the groove portion 50 is located below the insulating film 40. The groove portion 50 is formed, for example, by etching the SOI substrate to a level below the insulating film 40. The groove portion 50 is formed around the plurality of piezoresistive portions 20. The groove portion 50 surrounds all of the plurality of piezoresistive portions 20. The groove portion 50 is formed outside the outer peripheral end portion 12 of the diaphragm portion 10. The groove portion 50 is formed inside the fixing surface 32 of the support portion 30. The groove portion 50 surrounds the entire circumference of the outer peripheral end portion 12 of the diaphragm portion 10 (see FIG. 2). The groove portion 50 goes around the outer peripheral end portion 12 of the diaphragm portion 10 . The groove portion 50 extends continuously along the outer peripheral end portion 12. The groove portion 50 is formed in a circular shape.

In the sensor chip 1 described above, when the pressure of the liquid w inside the container 200 acts on the pressure receiving surface 14 of the diaphragm part 10, the diaphragm part 10 deforms so as to bend upward. When the diaphragm section 10 is deformed, distortion occurs in the plurality of piezoresistive sections 20 arranged in the diaphragm section 10. When distortion occurs in each piezoresistive section 20, the resistance value of each piezoresistive section 20 changes. Using the resistance values of the plurality of piezoresistive sections 20, stress in the diaphragm section 10 is detected based on a bridge circuit.

The sensor chip 1 according to the embodiment has been described above. As is clear from the above description, the sensor chip 1 includes the insulating film 40 extending in the direction along the pressure receiving surface 14 on the side closer to the pressure receiving surface 14 than the plurality of piezoresistive sections 20 . The sensor chip 1 also includes a groove portion extending from the surface opposite to the pressure receiving surface 14 (the upper surface of the support portion 30 ) to the bottom side of the insulation film 40 and penetrating the insulation film 40 around the plurality of piezoresistive portions 20 . It is equipped with 50. The groove portion 50 goes around the plurality of piezoresistive portions 20 when viewed in a direction perpendicular to the pressure receiving surface 14 .

According to this configuration, the plurality of piezoresistive parts 20 can be insulated from the surroundings by the insulating film 40 on the side closer to the pressure receiving surface 14 than the plurality of piezoresistive parts 20. Further, in the direction along the pressure receiving surface 14, the plurality of piezoresistive sections 20 can be insulated from the surroundings by the groove section 50 extending to the lower side of the insulating film 40. Therefore, even if the liquid w inside the container 200 has conductivity, current leakage from each piezoresistive part 20 to the liquid w can be suppressed. Furthermore, in the above configuration, since the groove portion 50 goes around the plurality of piezoresistive portions 20, stress in the diaphragm portion 10 is divided between the piezoresistive portions 20 and the piezoresistive portions 20 by the groove portion 50. Never. Therefore, it is possible to insulate the plurality of piezoresistive sections 20 from the surroundings and to detect stress in the diaphragm section 10 with high accuracy.

Furthermore, in the above configuration, the groove portion 50 extends through the insulating film 40. Therefore, the insulation of the plurality of piezoresistive sections 20 from the surroundings can be improved.

Further, in the above configuration, the sensor chip 1 is fixed to the inner surface 210 of the container 200 such that the pressure receiving surface 14 of the diaphragm portion 10 faces the inside of the container 200. According to this configuration, when the pressure of the fluid acts on the sensor chip 1, the sensor chip 1 is pressed against the inner surface 210 of the container 200, so that the sensor chip 1 can be firmly fixed to the container 200.

Although one embodiment has been described above, the specific aspect is not limited to the above embodiment. In the following description, the same components as those in the above description are designated by the same reference numerals, and the description thereof will be omitted.

(1) In another embodiment, as shown in FIG. 3, the opening 220 of the container 200 and the groove 50 of the sensor chip 1 may be filled with a filler 70. The filler 70 is made of an insulating material. The filler 70 is made of silicone resin or epoxy resin, for example. The filler 70 covers the upper surface of the diaphragm portion 10. Further, in other embodiments, a glass member 130 may be disposed below the support portion 30. The glass member 130 is fixed to the lower surface of the support section 30. The glass member 130 supports the support section 30. The glass member 130 includes an opening 132. The glass member 130 is arranged such that its opening 132 faces the pressure receiving surface 14 of the diaphragm portion 10.

(2) In yet another embodiment, as shown in FIG. 4, a plurality of grooves 50 may be formed in the support portion 30. The number of grooves 50 is not particularly limited.

(3) In the above embodiment, the groove portion 50 penetrates the insulating film 40 and extends to the lower side of the insulating film 40, but the structure is not limited to this. In other embodiments, as shown in FIG. 5, the groove 50 does not need to penetrate the insulating film 40. The groove portion 50 only needs to extend to a position where it reaches the insulating film 40. It is sufficient that the bottom surface 52 of the groove portion 50 reaches the insulating film 40 . This configuration also allows the plurality of piezoresistive sections 20 to be insulated from the surroundings.

(4) In the above embodiment, the insulating film 40 covers the pressure receiving surface 14 of the diaphragm portion 10, but the present invention is not limited to this structure. In other embodiments, as shown in FIG. 6, an insulating film 40 may be formed inside the diaphragm portion 10. The insulating film 40 may be disposed above the pressure receiving surface 14 of the diaphragm portion 10. In this configuration, the pressure receiving surface 14 is located below the insulating film 40. The pressure receiving surface 14 is in contact with the liquid w inside the container 200. Further, in the above embodiment, the groove portion 50 is formed in the support portion 30, but the structure is not limited to this. In other embodiments, a groove 50 may be formed in the diaphragm portion 10, as shown in FIG. With the configuration shown in FIG. 6 as well, it is possible to insulate the plurality of piezoresistive sections 20 from the surroundings and to detect stress in the diaphragm section 10 with high accuracy.

(5) In the above embodiment, the four piezoresistive sections 20 are arranged in the diaphragm section 10, but the present invention is not limited to this structure. In other embodiments, for example, two piezoresistive sections 20 may be arranged in the diaphragm section 10.

(6) In the above embodiment, the sensor chip 1 was fixed to the inner surface 210 of the container 200, but the structure is not limited to this. In other embodiments, the sensor chip 1 may be fixed to the outer surface of the container 200. In still another embodiment, the sensor chip 1 may be fixed to the inner surface of the tube 250. The member to which the sensor chip 1 is fixed is not particularly limited. It is sufficient that the pressure receiving surface 14 of the diaphragm portion 10 is disposed so as to face the liquid w side.

(7) In the embodiments described above, the liquid w was used as an example of the fluid, but the configuration is not limited to this, and in other embodiments, the fluid may be a gas.

(8) In the above embodiment, the sensor chip 1 was fixed to the container 200 with the adhesive 60, but the structure is not limited to this. In other embodiments, solder or low melting point glass may be used instead of the adhesive 60.

Although specific examples of the present invention have been described in detail above, these are merely illustrative and do not limit the scope of the claims. The techniques described in the claims include various modifications and changes to the specific examples illustrated above. The technical elements described in this specification or the drawings exhibit technical utility alone or in various combinations, and are not limited to the combinations described in the claims as filed. Furthermore, the techniques illustrated in this specification or the drawings can achieve multiple objectives simultaneously, and achieving one of the objectives has technical utility in itself.

1: Sensor chip, 10: Diaphragm section, 12: Outer peripheral end section, 14: Pressure receiving surface, 20: Piezoresistive section, 30: Support section, 32: Fixed surface, 40: Insulating film, 50: Groove section, 52: Bottom surface, 60: adhesive, 70: filler, 200: container, 210: inner surface

Claims (3)

A sensor chip made of a semiconductor,
a diaphragm portion including a pressure receiving surface that receives fluid pressure;
a support portion supporting an outer peripheral end portion of the diaphragm portion;
a plurality of piezoresistive parts arranged in the diaphragm part;
an insulating film extending in a direction along the pressure receiving surface on a side closer to the pressure receiving surface than the plurality of piezoresistive parts;
A groove extending around the plurality of piezoresistors from a surface opposite to the pressure receiving surface to a position reaching the insulating film, the plurality of piezoresistors when viewed in a direction perpendicular to the pressure receiving surface. and the groove part that goes around the part so as to surround the part ,
In the sensor chip, the groove portion extends through the insulating film . The sensor chip according to claim 1 , further comprising an insulating filler filled in the groove. The sensor chip according to claim 1 or 2, which is fixed to a container or a pipe,
The sensor chip is fixed to an inner surface of the container or the tube such that the pressure receiving surface of the diaphragm portion faces the inside of the container or the tube.

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