JP7707966B2 - Pressure Sensors - Google Patents

Description

This disclosure relates to filters.

Known structures include pressure guide paths in pressure sensors with semiconductor pressure sensor chips (see, for example, Patent Document 1), and flow paths in gas chromatographs, inkjet heads, and other MEMS (Micro Electro Mechanical Systems) with fine passages.

JP 2013-130453 A

Since foreign matter may travel through the pressure guideway or flow path and reach the sensor chip, it would be desirable to easily realize a filter function that can suppress the movement of foreign matter in a fine passageway.

Therefore, the objective of this disclosure is to provide a filter that can easily achieve filtering function in fine passages.

In some embodiments, the filter has two layer members that are stacked together, each of the layer members has a through hole that opens to the interface between the two layer members and to the surface opposite the interface, the two through holes do not overlap at the interface, and at least one of the layer members has a recessed passage at the interface that connects the two through holes. With this configuration, a filter function can be easily achieved by providing a recessed passage, making it possible to realize a filter that easily achieves a filter function with fine passages.

In one embodiment, the filter is a filter in which one of the layer members is made of semiconductor silicon and the other layer member is made of glass. With this configuration, the two layer members can be easily joined with high precision, for example by anodic bonding.

In one embodiment, the filter is a filter in which the layer member having the recessed passages is formed from semiconductor silicon. With this configuration, the recessed passages can be easily formed by a semiconductor process.

In one embodiment, the filter is a filter in which one of the layer members has a plurality of sets of the through holes and the recessed passages corresponding to the through holes of the other layer member. With this configuration, clogging of the filter can be suppressed.

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 recessed passages corresponding to the through holes. With this configuration, clogging of the filter can be suppressed.

In one embodiment, the method for manufacturing a filter includes a layer member forming step in which the layer member having the recessed passage is formed by a semiconductor process. With this configuration, the recessed passage can be easily provided.

In one embodiment, the method for manufacturing the filter is a method for manufacturing the filter in which the recessed passages are formed by etching in the layer member forming process. With this configuration, the recessed passages, and in particular multiple recessed passages, can be easily formed.

In one embodiment, the method for manufacturing a filter is a method for manufacturing a filter in which the through holes of the layer member having the recessed passages are formed by etching in the layer member forming step. With this configuration, through holes, particularly multiple through holes, can be easily formed.

In one embodiment, the method for manufacturing the filter includes a bonding step of anodically bonding the two layer members. With this configuration, for example, one layer member is made of semiconductor silicon and the other layer member is made of glass, so that the two layer members can be bonded easily with high precision.

In one embodiment, the method for manufacturing a filter includes a layer member forming step of forming the through holes and the recessed passages for one of the plurality of layer members in a semiconductor silicon wafer, a joining step of joining the semiconductor silicon wafer to a member for forming the other of the plurality of layer members to form a joint, and a cutting step of cutting the joint to form a plurality of filters. With this configuration, a plurality of filters can be manufactured efficiently.

In one embodiment, the pressure sensor includes the filter and a semiconductor pressure sensor chip that is laminated on one of the layer members. This configuration makes it possible to realize a pressure sensor that can easily achieve a filter function in a fine passage.

In one embodiment, the method for manufacturing the pressure sensor is the same as the method for manufacturing the filter. With this configuration, the pressure sensor can be manufactured advantageously.

This disclosure makes it possible to provide a filter that can easily achieve filtering function in fine passages.

FIG. 11 is an end view showing a pressure measuring device according to a comparative example. FIG. 1 is an end view of a pressure measuring instrument having a pressure sensor with a filter according to one embodiment. FIG. 3 is a top view of the pressure sensor shown in FIG. 2 . FIG. 1 is an end view of a semiconductor silicon wafer. This shows the state when the semiconductor silicon wafer shown in FIG. 4A is thermally oxidized. This shows a state when the thermal oxide film shown in FIG. 4B is etched. This shows the state when the semiconductor silicon wafer shown in FIG. 4C is etched. This shows the state when the thermal oxide film shown in FIG. 4D is etched. This shows the state when the semiconductor silicon wafer shown in FIG. 4E is thermally oxidized. This shows the state when the thermal oxide film shown in FIG. 4F is etched. This shows the state when the semiconductor silicon wafer shown in FIG. 4G is etched. This shows the state when the thermal oxide film shown in FIG. 4H is etched. This shows a state where the semiconductor silicon wafer shown in FIG. 4I is bonded to a semiconductor silicon wafer on which a diaphragm is formed. FIG. 4J shows a state in which the semiconductor silicon wafer having the recessed passages and through-holes formed therein is bonded to a glass member having through-holes formed therein. 4K is cut to form a plurality of pressure sensors. FIG. 3 is a top view showing a modified example of the pressure sensor shown in FIG. 2 .

Embodiments of the present disclosure are described in detail below with reference to the drawings.

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

The sensor chip 4 is made of semiconductor silicon or the like. The sensor chip 4 also has a recess 6 at the interface with the glass base 5, which forms a diaphragm 7 and a recessed space 8 of the sensor chip 4. The glass base 5 has a through passage 9 that opens at the interface with the passage member 3 and on the surface opposite the interface. The passage member 3 is made of metal or the like. The passage member 3 also has a passage 10 that opens at the interface with the glass base 5.

The passage 10, through passage 9 and recessed space 8 function as a pressure transmission path that transmits the pressure of the part to be measured, which is measured by the pressure measuring device 1, to the diaphragm 7. The pressure difference between the pressure in the recessed 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 part to be measured can be measured by detecting an electrical signal or the like that is generated in response to the distortion of the diaphragm 7. A pressure transmission medium such as silicone oil may be appropriately enclosed in the pressure transmission path.

Foreign matter 12, such as cutting chips generated when cutting the passage 10 or the through passage 9, may be present in the pressure transmission path. If the foreign matter 12 moves into the recessed space 8 and adheres to the diaphragm 7 when the pressure transmission medium is sealed, this may cause the sensor to exhibit poor characteristics.

To prevent such sensor characteristic defects, in one embodiment shown in Figures 2 and 3, the pressure sensor 2 has a filter 13.

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, and the filter 13 has two layer members 14, 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 in this order and integrated. 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 from semiconductor silicon or the like, and the second layer member 14b is formed from glass or the like. The pressure sensor 2 of this embodiment constitutes a MEMS.

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

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

As shown in FIG. 3, the first through holes 16a and the second through holes 16b do not overlap at the intermediate interface 15. In a top view, the second through hole 16b is located between two first through holes 16a aligned in the first direction, and the second through hole 16b is located between two first through holes 16a aligned in the second direction. The cross-sectional shape of each first through hole 16a is a rectangle with 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 a circle. These cross-sectional shapes can be changed as appropriate.

As shown in Figures 2 and 3, the first layer member 14a has four groove-shaped concave passages 17 at the intermediate interface 15 that connect the four first through holes 16a to the second through holes 16b. Each concave passage 17 extends between the corresponding first through hole 16a and 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.

The lower end of the second through hole 16b communicates with the upper end of the passage 10. The upper ends of the first through holes 16a communicate with the lower ends of the recessed spaces 8. The lower surface of the sensor chip 4 is bonded to the upper surface of the first layer member 14a, the lower surface of the first layer member 14a is bonded to the upper surface of the second layer member 14b, and the lower surface of the second layer member 14b is bonded to the upper surface of the passage member 3.

The inner diameter (minimum width in 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 foreign matter 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 cross section of the concave passage 17, it is possible to suppress the intrusion of the foreign matter 12 into the concave space 8, and as a result, the occurrence of sensor characteristic defects can be suppressed. In addition, in this embodiment, by having multiple sets of first through holes 16a and concave passages 17, clogging by the foreign matter 12 can be suppressed, and thus a good pressure transmission function as a pressure transmission path can be maintained. The recessed passage 17 is not limited to a shape that extends radially from the second through hole 16b when viewed from above as shown in FIG. 3, but may have a shape in which the circumferential length is greater than the radial length.

In addition, according to this embodiment, it is also possible to use the concave passage 17 as a throttle that attenuates the impact pressure that may be transmitted through the pressure transmission path and cause the diaphragm 7 to break. In other words, by appropriately setting the cross-sectional shape and size of the concave passage 17, it is possible to suppress the peak value of a pulsed pressure wave that has a pulse width significantly shorter than the time constant of the pressure change to be detected by the pressure sensor.

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

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

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 process shown in FIG. 4A to FIG. 4I. First, the first semiconductor silicon wafer 22 shown in FIG. 4A is thermally oxidized to form a first thermal oxide film 23 as shown in FIG. 4B. Next, as shown in FIG. 4C, the portion of the first thermal oxide film 23 corresponding to the recessed passage 17 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 the recessed passage 17. Next, as shown in FIG. 4E, the first thermal oxide film 23 is entirely removed by etching. Next, as shown in FIG. 4F, the first semiconductor silicon wafer 22 is thermally oxidized again to form a second thermal oxide film 24. Next, as shown in FIG. 4G, the portion of the second thermal oxide film 24 corresponding to the through hole 16 is removed by etching. Next, as shown in FIG. 4H, the first semiconductor silicon wafer 22 is anisotropically etched using a KOH solution or the like to form the first through-hole 16a. Then, as shown in FIG. 4I, the second thermal oxide film 24 is entirely removed by etching to form the first layer structure 18.

In the bonding process, the sensor structure 21 is formed by the process shown in Figures 4J to 4K. First, as shown in Figure 4J, the first layer structure 18 and the sensor chip structure 20 made of the second semiconductor silicon wafer on which the diaphragm 7 is formed are directly bonded together. Next, as shown in Figure 4K, the first layer structure 18 and the second layer structure 19 formed by forming second through holes 16b in the glass member to form multiple second layer members 14b are bonded together by anodic bonding to form the sensor structure 21.

In the cutting process, as shown in FIG. 4L, the sensor structure 21 is cut by dicing to form multiple pressure sensors 2.

In the embodiment described above, one recessed passage 17 is provided corresponding to one first through hole 16a, but as in the modified example shown in FIG. 5, multiple recessed passages 17 extending, for example, parallel to each other, may be provided corresponding to one first through hole 16a. According to this embodiment, it is easy to realize a filter function for small foreign matter 12. In addition, according to this embodiment, it is easy to realize a clogging suppression effect and an impact pressure attenuation effect.

This disclosure is not limited to the above-described embodiments, and various modifications are possible without departing from the spirit of the present disclosure.

Therefore, the filter 13 according to the embodiment described above can be modified in various ways as long as it is a filter 13 that has two layer members 14 that are stacked, each layer member 14 having a through hole 16 that opens to the interface between the two layer members 14 and the surface opposite the interface, the two through holes 16 do not overlap at the interface, and at least one layer member 14 has a recessed passage 17 at the interface that connects the two through holes 16.

The pressure sensor 2 according to the embodiment described above can be modified in various ways as long as it is a pressure sensor 2 having a filter 13 and a semiconductor pressure sensor chip 4 stacked on one of the layer members 14.

For example, the material of the two layer members 14 can be set appropriately. 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 appropriately. For example, the filter 13 may have one each of the first through hole 16a, the concave passage 17, and the second through hole 16b. The concave passage 17 is not limited to being provided only in the first layer member 14a, but 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 with 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 can be used to realize a filter function in various passages, such as the passages of a gas chromatograph, an inkjet head, etc., not limited to the pressure sensor 2.

In addition, the filter 13 according to the embodiment described above is preferably a filter 13 in which one layer member 14 is formed from semiconductor silicon and the other layer member 14 is formed from glass.

The filter 13 according to the embodiment described above is preferably a filter 13 in which the layer member 14 having the recessed passage 17 is formed from semiconductor silicon.

The filter 13 according to the embodiment described above is preferably a filter 13 in which one layer member 14 has multiple sets of through holes 16 and recessed passages 17 corresponding to the through holes 16 of the other layer member 14.

The filter 13 according to the embodiment described above is preferably a filter 13 in which at least one layer member 14 has a through hole 16 and a plurality of recessed passages 17 corresponding to the through hole 16.

The filter 13 according to the embodiment described above is preferably manufactured by a method including a layer member forming step in which a layer member 14 having recessed passages 17 is formed by a semiconductor process.

The filter 13 according to the embodiment described above is preferably manufactured by a method in which the recessed passages 17 are formed by etching during the layer member formation process.

The filter 13 according to the embodiment described above is preferably manufactured by a method in which the through holes 16 in the layer member 14 having the recessed passages 17 are formed by etching during the layer member formation process.

The filter 13 according to the above-described embodiment is preferably manufactured by a method that includes a bonding process in which the two layer members 14 are anodically bonded.

The filter 13 according to the embodiment described above is preferably manufactured by a method including a layer member forming step of forming through holes 16 and recessed passages 17 for a plurality of one layer members 14 in a semiconductor silicon wafer, a joining step of joining the semiconductor silicon wafer to members for forming the plurality of other layer members 14 to form a joint, and a cutting step of cutting the joint to form a plurality of filters 13.

The pressure sensor 2 according to the embodiment described above is preferably manufactured using the manufacturing method for the filter 13 described above.

REFERENCE SIGNS LIST 1 Pressure measuring device 2 Pressure sensor 3 Passage member 4 Sensor chip 5 Glass base 6 Recess 7 Diaphragm 8 Recessed space 9 Through passage 10 Passage 11 Outside 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 Recessed 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 (4)

A filter and a semiconductor pressure sensor chip are included.
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 recessed passage at the interface that communicates the two through holes,
one of the layer members has a plurality of sets of the through holes and the recessed passages corresponding to the through holes of the other of the layer members;
The semiconductor pressure sensor chip is laminated on the layer member having the plurality of sets of through holes and recessed passages;
the semiconductor pressure sensor chip has a recess forming a diaphragm and a recess space at an interface with the layer member having the plurality of sets of through holes and recessed passages;
A pressure sensor in which, when the direction from the layer member having the multiple sets of through holes and recessed passages along the stacking direction toward the semiconductor pressure sensor chip is defined as upward, the upper ends of the through holes of each of the layer members are connected to the lower ends of the recessed spaces . 2. The pressure sensor according to claim 1, wherein one of said layer members is made of semiconductor silicon and the other of said layer members is made of glass. 3. The pressure sensor according to claim 1, wherein the layer member having the recessed passage is made of semiconductor silicon. A method for manufacturing the pressure sensor according to any one of claims 1 to 3, comprising the steps of:
A method for manufacturing a pressure sensor , comprising the step of forming the layer member having the recessed passages by a semiconductor process.