Pressure sensor

Abstract

To provide a filter capable of easily realizing a filter function in a minute passage.SOLUTION: A filter 13 has two layer members 14 that are laminated. Each layer member 14 has a through hole 16 that opens at an interface between the two layer members 14 and a surface opposite to the interface. The two through holes 16 do not overlap at the interface. At least one layer member 14 has, at the interface, a concave passage 17 that communicates the two through holes 16.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a filter.

Background Art

[0002] Structures such as MEMS (Micro Electro Mechanical Systems) having fine passages are known, such as a pressure guiding path of a pressure sensor having a semiconductor pressure sensor chip (see, for example, Patent Document 1), a flow path of a gas chromatograph, an inkjet head, and the like.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Since foreign matter may move through the pressure guiding path or the flow path and reach the sensor chip or the like, it is desirable to easily realize a filter function for suppressing the movement of foreign matter in a fine passage.

[0005] Therefore, an object of the present disclosure is to provide a filter that can easily realize a filter function in a fine passage.

Means for Solving the Problems

[0006] In some embodiments, the filter has two laminated layer members, each of the layer members having a through hole that opens to the interface between the two layer members and the surface opposite to the interface, the two through holes not overlapping at the interface, and at least one of the layer members having a concave passage communicating the two through holes at the interface. According to such a configuration, since the filter function can be easily realized by providing the concave passage, a filter that can easily realize the filter function in a fine passage can be realized.

[0007] In one embodiment, the filter is a filter in which one of the layer members is formed of semiconductor silicon and the other layer member is formed of glass. According to such a configuration, for example, two layer members can be easily and accurately joined by anodic bonding.

[0008] In one embodiment, the filter is a filter in which the layer member having the concave passage is formed of semiconductor silicon. According to such a configuration, the concave passage can be easily provided by a semiconductor process.

[0009] In one embodiment, the filter is a filter in which one of the layer members has a plurality of sets of through holes and the concave passage corresponding to the through holes of the other layer member. According to such a configuration, clogging of the filter can be suppressed.

[0010] In one embodiment, the filter is a filter in which at least one of the layer members has the through holes and a plurality of the concave passages corresponding to the through holes. According to such a configuration, clogging of the filter can be suppressed.

[0011] In one embodiment, a method for manufacturing the filter includes a layer member forming step of forming the layer member having the concave passage by a semiconductor process. According to such a configuration, the concave passage can be easily provided.

[0012] In one embodiment, a method for manufacturing the filter is a method for manufacturing the filter in which the concave passage is formed by etching in the layer member forming step. According to such a configuration, the concave passage can be easily provided, particularly a plurality of concave passages can be easily provided.

[0013] In one embodiment, a method for manufacturing a filter is the method for manufacturing the filter in which the through holes of the layer member having the concave passages are formed by etching in the layer member forming step. According to such a configuration, through holes can be easily provided, particularly a plurality of through holes.

[0014] In one embodiment, a method for manufacturing a filter is the method for manufacturing the filter having a bonding step of anodic bonding the two layer members. According to such a configuration, for example, by forming one layer member of semiconductor silicon and the other layer member of glass, the two layer members can be easily bonded with high precision.

[0015] In one embodiment, a method for manufacturing a filter includes a layer member forming step of forming the through holes and the concave passages for a plurality of the one layer members in a semiconductor silicon wafer, a bonding step of bonding the semiconductor silicon wafer to a member for forming a plurality of the other layer members to form a bonded body, and a cutting step of cutting the bonded body to form a plurality of filters. According to such a configuration, a plurality of filters can be efficiently manufactured.

[0016] In one embodiment, a pressure sensor includes the filter and a semiconductor pressure sensor chip laminated on one of the layer members. According to such a configuration, a pressure sensor that can easily realize a filter function in a fine passage can be realized.

[0017] In one embodiment, a method for manufacturing a pressure sensor is the method for manufacturing the pressure sensor according to the method for manufacturing the filter. According to such a configuration, a pressure sensor can be advantageously manufactured.

Advantages of the Invention

[0018] According to the present disclosure, a filter that can easily realize a filter function in a fine passage can be provided.

Brief Description of the Drawings

[0019]

Figure 1

Figure 2

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Figure 4B

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Figure 4F

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Figure 4H

Figure 4I

Figure 4J

Figure 4K

Figure 4L

Figure 5

Mode for Carrying Out the Invention

[0020] Hereinafter, embodiments of the present disclosure will be exemplified and described in detail with reference to the drawings.

[0021] The pressure measuring device 1 according to the comparative example shown in FIG. 1 has a pressure sensor 2 and a passage member 3. The pressure sensor 2 has a semiconductor pressure sensor chip 4 (hereinafter also referred to as the sensor chip 4) and a glass pedestal 5. The sensor chip 4, the glass pedestal 5, and the passage member 3 are stacked and integrated in this order.

[0022] The sensor chip 4 is formed of semiconductor silicon or the like. The sensor chip 4 has a recess 6 at the interface with the glass pedestal 5, and the recess 6 forms a diaphragm 7 and a concave space 8 of the sensor chip 4. The glass pedestal 5 has a through passage 9 that opens at the interface with the passage member 3 and the surface on the opposite side of the interface. The passage member 3 is formed of metal or the like. The passage member 3 also has a passage 10 that opens at the interface with the glass pedestal 5.

[0023] The passage 10, the through passage 9, and the concave space 8 function as a pressure transmission path that transmits the pressure of the measured portion measured by the pressure measuring device 1 to the diaphragm 7. The differential pressure between the pressure in the concave space 8 and the pressure in the outer space 11 of the diaphragm 7 is applied to the diaphragm 7, and the pressure of the measured portion can be measured by detecting an electrical signal or the like generated according to the strain of the diaphragm 7. In some cases, a pressure transmission medium such as silicone oil is appropriately enclosed in the pressure transmission path.

[0024] Foreign matter 12 such as chips generated when forming the passage 10 or the through passage 9 by cutting may exist in the pressure transmission path. If the foreign matter 12 moves into the concave space 8 and adheres to the diaphragm 7 when the pressure transmission medium is enclosed, there is a risk of causing defective sensor characteristics.

[0025] In order to suppress such defective sensor characteristics, in one embodiment shown in FIGS. 2 to 3, the pressure sensor 2 has a filter 13.

[0026] In this embodiment, the pressure measuring device 1 has a pressure sensor 2 and a passage member 3. The pressure sensor 2 has a sensor chip 4 and a filter 13. The filter 13 has two layer members 14, namely a first layer member 14a and a second layer member 14b. The sensor chip 4, the first layer member 14a, the second layer member 14b, and the passage member 3 are stacked and integrated in this order. The sensor chip 4 and the passage member 3 are configured in the same manner as in the comparative example. The first layer member 14a is formed of semiconductor silicon or the like, and the second layer member 14b is formed of glass or the like. The pressure sensor 2 of this embodiment constitutes a MEMS.

[0027] Each layer member 14 has through holes 16 that open to the interface between the two layer members 14 (hereinafter also referred to as the intermediate interface 15) and the surface on the opposite side of the intermediate interface 15. More specifically, the first layer member 14a has four first through holes 16a that open to the intermediate interface 15 and the surface on the opposite side of the interface, respectively, and the second layer member 14b has one second through hole 16b that opens to the intermediate interface 15 and the surface on the opposite side of the interface. The four first through holes 16a consist of two first through holes 16a arranged side by side in a first direction (the horizontal direction in FIG. 3) perpendicular to the stacking direction (the direction perpendicular to the paper surface in FIG. 3), and two first through holes 16a arranged side by side in a second direction (the vertical direction in FIG. 3) perpendicular to the stacking direction and the first direction.

[0028] In this embodiment, for the sake of convenience of explanation, the stacking direction is also referred to as the vertical direction, the direction from the second layer member 14b toward the first layer member 14a along the vertical direction is also referred to as upward, and the opposite direction is also referred to as downward.

[0029] As shown in FIG. 3, each of the first through holes 16a and the second through hole 16b do not overlap at the intermediate interface 15. In a top view, the second through hole 16b is located between the two first through holes 16a arranged in the first direction, and the second through hole 16b is located between the two first through holes 16a arranged in the second direction. The cross-sectional shape of each first through hole 16a is a rectangle composed of two sides extending in the first direction and two sides extending in the second direction, and the cross-sectional shape of the second through hole 16b is circular. It should be noted that these cross-sectional shapes can be appropriately changed.

[0030] As shown in FIGS. 2 to 3, the first layer member 14a has four groove-shaped concave passages 17 in the intermediate interface 15 that connect the four first through-holes 16a to the second through-hole 16b. Each concave passage 17 extends between the corresponding first through-hole 16a and the second through-hole 16b so as to connect the corresponding first through-hole 16a to the second through-hole 16b. Thus, in this embodiment, four sets of first through-holes 16a and concave passages 17 are provided corresponding to one second through-hole 16b. Also, in this embodiment, one concave passage 17 is provided corresponding to one first through-hole 16a.

[0031] The lower end of the second through-hole 16b communicates with the upper end of the passage 10. Also, the upper end of each first through-hole 16a communicates with the lower end of the concave space 8. The lower surface of the sensor chip 4 is joined to the upper surface of the first layer member 14a, the lower surface of the first layer member 14a is joined to the upper surface of the second layer member 14b, and the lower surface of the second layer member 14b is joined to the upper surface of the passage member 3.

[0032] The inner diameter (minimum width in the cross-section) of each concave passage 17 extending radially from the second through-hole 16b of the second layer member 14b is smaller than the inner diameter of the second through-hole 16b. Therefore, each concave passage 17 can block a foreign object 12 larger than the concave passage 17 that moves through the second through-hole 16b from below the concave passage 17. Therefore, by appropriately setting the shape and size of the concave passage 17 in the cross-section, etc., it is possible to suppress the foreign object 12 from entering the concave space 8, and as a result, suppress the occurrence of deterioration in the characteristics of the sensor. Also, in this embodiment, by having a plurality of sets of first through-holes 16a and concave passages 17, clogging by the foreign object 12 can be suppressed, and thus a good pressure transmission function as a pressure transmission path can be maintained. Note that the concave passage 17 is not limited to a shape that extends elongated radially from the second through-hole 16b in a top view as shown in FIG. 3, and may have a configuration in which the circumferential length is larger than the radial length.

[0033] Also, according to the present embodiment, it is also possible to use the concave-shaped passage 17 as a throttle that attenuates the impact pressure that can cause the diaphragm 7 to break while traveling through the pressure transmission path. That is, by appropriately setting the shape and size of the concave-shaped passage 17 in the cross-section, it is possible to suppress the peak value of the pulsed pressure wave having a pulse width significantly shorter than the time constant of the pressure change to be detected as the pressure sensor.

[0034] The pressure sensor 2 can be manufactured, for example, by a manufacturing method according to an embodiment shown in FIGS. 4A to 4L (hereinafter also referred to as this manufacturing method).

[0035] This manufacturing method includes a layer member forming step (FIGS. 4A to 4I), a bonding step (FIGS. 4J to 4K), and a cutting step (FIG. 4L). The layer member forming step is a step of forming the first layer structure 18. The bonding step is a step of bonding the sensor chip structure 20, the first layer structure 18, and the second layer structure 19 to form the sensor structure 21. The cutting step is a step of forming a plurality of pressure sensors 2 by cutting the sensor structure 21. According to this manufacturing method, since a plurality of pressure sensors 2 can be manufactured simultaneously using a semiconductor process, low cost can be realized.

[0036] In the layer member forming process, a first layer structure 18 is formed from a first semiconductor silicon wafer 22 for forming a plurality of first layer members 14a. The first layer structure 18 is formed by the processes shown in FIGS. 4A to 4I. First, by thermally oxidizing the first semiconductor silicon wafer 22 shown in FIG. 4A, a first thermal oxide film 23 is formed as shown in FIG. 4B. Next, as shown in FIG. 4C, the portion corresponding to the concave passage 17 in the first thermal oxide film 23 is removed by etching. Next, as shown in FIG. 4D, the surface of the first semiconductor silicon wafer 22 is removed by etching through the opening of the first thermal oxide film 23 to form a concave passage 17. Next, as shown in FIG. 4E, the entire first thermal oxide film 23 is removed by etching. Next, as shown in FIG. 4F, by thermally oxidizing the first semiconductor silicon wafer 22 again, a second thermal oxide film 24 is formed. Next, as shown in FIG. 4G, the portion corresponding to the through hole 16 in the second thermal oxide film 24 is removed by etching. Next, as shown in FIG. 4H, the first semiconductor silicon wafer 22 is anisotropically etched using an aqueous KOH solution or the like to form a first through hole 16a. Then, as shown in FIG. 4I, by removing the entire second thermal oxide film 24 by etching, the first layer structure 18 is formed.

[0037] In the bonding process, a sensor structure 21 is formed by the processes shown in FIGS. 4J to 4K. First, as shown in FIG. 4J, the first layer structure 18 and a sensor chip structure 20 composed of a second semiconductor silicon wafer on which a diaphragm 7 is formed are bonded by direct bonding. Next, as shown in FIG. 4K, the sensor structure 21 is formed by bonding the first layer structure 18 and a second layer structure 19 formed by forming a second through hole 16b in a glass member for forming a plurality of second layer members 14b by anodic bonding.

[0038] In the cutting process, as shown in FIG. 4L, the sensor structure 21 is cut by dicing to form a plurality of pressure sensors 2.

[0039] In the above-described embodiment, one concave passage 17 is provided corresponding to one first through-hole 16a. However, as in the modification shown in FIG. 5, a plurality of concave passages 17, for example, extending parallel to each other, may be provided corresponding to one first through-hole 16a. According to the present embodiment, it is possible to easily realize a filter function for small foreign matter 12. Further, according to the present embodiment, it is also possible to easily realize a clogging suppression effect and an impact pressure attenuation effect.

[0040] The present disclosure is not limited to the above-described embodiments, and various modifications can be made without departing from the gist thereof.

[0041] Therefore, as long as the filter 13 according to the above-described embodiment has two laminated layer members 14, each layer member 14 has through-holes 16 opening to the interface between the two layer members 14 and the surface on the opposite side of the interface, the two through-holes 16 do not overlap at the interface, and at least one layer member 14 has a concave passage 17 communicating the two through-holes 16 at the interface, various modifications are possible.

[0042] Further, as long as the pressure sensor 2 according to the above-described embodiment has a filter 13 and a semiconductor pressure sensor chip 4 laminated on one layer member 14, various modifications are possible.

[0043] For example, the materials of the two layer members 14 can be set as appropriate. The number of the first through holes 16a is not limited to four, and the number, shape, arrangement, etc. of the first through holes 16a can be set as appropriate. For example, the filter 13 may be configured to have one first through hole 16a, one concave passage 17, and one second through hole 16b. The concave passage 17 is not limited to being provided only in the first layer member 14a. For example, it may be provided only in the second layer member 14b, or may be provided in both the first layer member 14a and the second layer member 14b. The concave passage 17 provided in the first layer member 14a and the concave passage 17 provided in the second layer member 14b may be combined to form a passage having an inner diameter smaller than the inner diameter of the second through hole 16b. The manufacturing method of the filter 13 and the pressure sensor 2 is not particularly limited. The filter 13 is not limited to the pressure sensor 2, and can be used to realize the filter function in various passages, such as the flow paths of gas chromatographs, inkjet heads, etc.

[0044] Note that the filter 13 according to the above-described embodiment is preferably a filter 13 in which one layer member 14 is formed of semiconductor silicon and the other layer member 14 is formed of glass.

[0045] The filter 13 according to the above-described embodiment is preferably a filter 13 in which the layer member 14 having the concave passage 17 is formed of semiconductor silicon.

[0046] The filter 13 according to the above-described embodiment is preferably a filter 13 in which one layer member 14 has a plurality of sets of through holes 16 and concave passages 17 corresponding to the through holes 16 of the other layer member 14.

[0047] The filter 13 according to the above-described embodiment is preferably a filter 13 in which at least one layer member 14 has through holes 16 and a plurality of concave passages 17 corresponding to the through holes 16.

[0048] The filter 13 according to the above-described embodiment is preferably manufactured by a method having a layer member forming step of forming the layer member 14 having the concave passage 17 by a semiconductor process.

[0049] The filter 13 according to the above-described embodiment is preferably manufactured by a method in which the concave passage 17 is formed by etching in the layer member forming step.

[0050] The filter 13 according to the above-described embodiment is preferably manufactured by a method in which the through hole 16 of the layer member 14 having the concave passage 17 is formed by etching in the layer member forming step.

[0051] The filter 13 according to the above-described embodiment is preferably manufactured by a method having a bonding step of anodically bonding two layer members 14.

[0052] The filter 13 according to the above-described embodiment preferably includes a layer member forming step of forming a through hole 16 and a concave passage 17 for a plurality of one layer members 14 in a semiconductor silicon wafer, a bonding step of bonding the semiconductor silicon wafer to a member for forming a plurality of other layer members 14 to form a bonded body, and a cutting step of cutting the bonded body to form a plurality of filters 13.

[0053] The pressure sensor 2 according to the above-described embodiment is preferably manufactured by the manufacturing method of the filter 13 described above.

Explanation of Reference Numerals

[0054] 1 Pressure measuring instrument 2 Pressure sensor 3 Passage member 4 Sensor chip 5 Glass pedestal 6 Concave portion 7 Diaphragm 8 Concave space 9 Through passage 10 Passage 11 Outer space 12 Foreign matter 13 Filter 14 Layer member 14a First layer member 14b Second layer member 15 Intermediate interface 16 Through-hole 16a First through-hole 16b Second through-hole 17 Concave-shaped passage 18 First layer structure 19 Second layer structure 20 Sensor chip structure 21 Sensor structure 22 First semiconductor silicon wafer 23 First thermal oxide film 24 Second thermal oxide film

Claims

**Claim 1**: A pressure sensor comprising a filter and a semiconductor pressure sensor chip, wherein the filter has two laminated layer members, each of the layer members has a through hole that opens to an interface between the two layer members and a surface opposite to the interface, the two through holes do not overlap at the interface, at least one of the layer members has a concave passage communicating the two through holes at the interface, one of the layer members has a plurality of sets of the through holes and the concave passage corresponding to the through holes of the other layer member, the semiconductor pressure sensor chip is laminated on the layer member having the plurality of sets of through holes and the concave passage, the semiconductor pressure sensor chip has a recess forming a diaphragm and a concave space at an interface with the layer member having the plurality of sets of through holes and the concave passage, a pressure sensor, wherein when the direction from the layer member having the plurality of sets of through holes and the concave passage toward the semiconductor pressure sensor chip along the lamination direction is defined as upward, an upper end of each of the through holes of the layer member communicates with a lower end of the concave space. **Claim 2** The pressure sensor according to claim 1, wherein one of the layer members is formed of semiconductor silicon and the other layer member is formed of glass. **Claim 3** The pressure sensor according to claim 1 or 2, wherein the layer member having the concave passage is formed of semiconductor silicon. **Claim 4** A method for manufacturing the pressure sensor according to any one of claims 1 to 3, the method for manufacturing a pressure sensor having a layer member forming step of forming the layer member having the concave passage by a semiconductor process.

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