JP7834003B2 - Capacitive pressure sensor and method for manufacturing a capacitive pressure sensor - Google Patents

Description

This invention relates to a capacitive pressure sensor in which a stacked baffle is compactly welded, and to a method for manufacturing this capacitive pressure sensor.

Pressure sensors, which output pressure values from the deflection (displacement) of a diaphragm under pressure, are widely used in industrial applications, including semiconductor equipment. In the manufacturing of semiconductor devices, various thin-film deposition systems using vapor phase growth and dry etching systems are employed. In such manufacturing equipment, precise control of the pressure within the processing chamber and the partial pressure of the process gas is crucial for forming thin films with thicknesses in the nanometer range, making accurate pressure measurement essential. Pressure sensors are used for this purpose.

This type of pressure sensor requires corrosion resistance to gases used in the equipment, such as process gases, as well as resistance to by-products generated during processes such as film deposition. Furthermore, in film deposition processes, deposits accumulate in areas through which the process gas passes, such as the walls of the deposition chamber, the inner walls of the piping, the inside of the vacuum pump, and the diaphragm, which is the pressure-receiving part of the pressure sensor, causing various problems.
For example, there is atomic layer deposition (ALD), which has been developed in recent years and is used for forming gate insulating films and the like, as it offers superior step coverage and film quality compared to the conventionally used chemical vapor deposition (CVD). However, due to its characteristics, ALD tends to cause material gas to adhere to various points through which the material gas passes, leading to the unwanted deposition mentioned above. As is well known, if such unwanted deposition occurs on the diaphragm of a pressure sensor, it can cause zero-point shifts and changes in pressure sensitivity, hindering accurate measurements and significantly affecting the processing results.

To prevent unwanted deposition on the diaphragm, as mentioned above, various parts are heated to approximately 200°C during processes such as film deposition. Furthermore, techniques have been proposed to prevent unwanted deposition on the diaphragm by complicating the process gas path to the diaphragm using baffles or other means, thereby capturing unwanted deposition along the way.

Conventional capacitive pressure sensors equipped with baffles to detect unnecessary deposits along the way include, for example, those described in Patent Document 1. Patent Document 1 shows a part of a capacitive pressure sensor, as shown in Figure 13. Figure 13 depicts a housing 2 having a fluid chamber 1 into which the fluid to be measured is introduced, a sensor chip 3 for detecting the pressure of the fluid to be measured in the fluid chamber 1, and a baffle 4 that divides the fluid chamber 1 into one end where the fluid to be measured is introduced and the other end where the sensor chip 3 is located.

The sensor chip 3 has a diaphragm 3a that receives the pressure of the fluid to be measured, and is supported by the housing 2 via a support diaphragm 5 and base plates 6 and 7 that sandwich the support diaphragm 5.
The baffle 4 is made up of multiple plate-shaped parts stacked together, and consists of an annular plate-shaped base plate 9 welded to the annular mounting seat 8 of the housing 2, multiple annular plate-shaped flow path plates 10 stacked on the base plate 9, and a disc-shaped top plate 11 that is placed on top of the flow path plates 10 and closes the hollow portion of the flow path plates 10.

The base plate 9 is formed to have a larger outer diameter than the numerous flow path plates 10 so that its outer circumference can be welded to the mounting seat 8.
The flow channel plate 10 has numerous flow channels 12 extending from the inner circumference to the outer circumference. These flow channels 12 are designed so that deposits are generated as the fluid to be measured passes through them.
To form this baffle 4, first, a number of flow path plates 10 and a top plate 11 are stacked and positioned on the same axis, and these components are joined to each other by diffusion bonding to form a flow path plate assembly. Next, a base plate 9 is stacked on the flow path plate assembly and these are positioned on the same axis and joined to each other by diffusion bonding. Conventional baffles 4 are manufactured through these two diffusion bonding processes.

In this conventional capacitive pressure sensor configuration, the fluid to be measured, introduced into the fluid chamber 1, passes through the flow path 12 of the flow path plate 10 and through the baffle 4 from the inner circumference to the outer circumference. This prevents deposits from forming on the flow path plate 10 and thus prevents deposit formation on the sensor chip 3.

Japanese Patent Publication No. 2015-34786

The baffle 4 complicates the path of the fluid to be measured, such as process gas, to the diaphragm 3a of the sensor chip 3, preventing unnecessary deposits from accumulating on the diaphragm 3a by trapping them along the way. Therefore, the lifespan of the capacitive pressure sensor is affected by the performance of the baffle 4. The performance of the baffle 4 varies depending on the width, shape, and length of the flow path 12. However, with the miniaturization of capacitive sensors, there is a demand for a baffle that can miniaturize the capacitive pressure sensor without compromising performance.

Furthermore, in conventional baffles 4, the base plate 9 is formed larger than the other plates (flow channel plate 10, top plate 11) to secure welding allowance for welding to the housing 2 of the capacitive pressure sensor. When components with different outer diameters are stacked and joined at once by diffusion bonding, the pressure distribution tends to become uneven, easily degrading the quality of the baffle 4. To resolve this problem, a method is employed in which multiple flow channel plates 10 and top plate 11 with the same outer diameter are joined to each other by diffusion bonding to form an assembly, and then the base plate 9 is stacked on top of this assembly and joined to each other by diffusion bonding. However, this introduces a new problem: two diffusion bonding steps are required.

The objectives of this invention are to provide a baffle that enables further miniaturization of capacitive pressure sensors without compromising performance, and to enable the easy manufacture of the baffle through a single-step diffusion bonding process.

To achieve this objective, the capacitive pressure sensor according to the present invention comprises a housing having a fluid chamber into which a fluid to be measured is introduced, a sensor chip for detecting the pressure of the fluid to be measured in the fluid chamber, and a baffle that divides the fluid chamber into one end into which the fluid to be measured is introduced and the other end into which the sensor chip is located, and connects the one end and the other end by a flow path through which deposits are generated as the fluid to be measured passes. The baffle is formed in the shape of an annular plate, and has numerous groove-shaped flow paths that open to the inner and outer circumferences and extend radially, and has a thickness The baffle comprises a plurality of flow path plates stacked and joined together in a specific direction, a base plate formed in an annular shape and joined to one end of the plurality of flow path plates in the stacking direction, and a top plate joined to the other end of the plurality of flow path plates in the stacking direction to close the hollow portion of the flow path plates. Multiple grooves extending in the stacking direction are formed on the outer circumference of the baffle, with one end of each groove closed by the base plate and the other end open. The portion of the base plate exposed to the grooves is welded to the housing.

In the present invention, the capacitive pressure sensor may be formed such that the flow path plate, the base plate, and the top plate have the same outer diameter.

In the present invention, in the capacitive pressure sensor, the inner wall of the fluid chamber where the baffle is arranged is formed by a peripheral wall that has a predetermined gap between it and the outer surface of the baffle, and the gap may be less than or equal to the depth of the groove-shaped flow path.

The method for manufacturing a capacitive pressure sensor according to the present invention comprises the steps of forming a stacked baffle having a channel through which deposits are generated as the fluid to be measured passes, and welding the baffle to a housing having a fluid chamber into which the fluid to be measured is introduced at one end and a sensor chip for detecting the pressure of the fluid to be measured in the fluid chamber provided at the other end, such that the one end and the other end are separated and the one end and the other end are connected by the channel, wherein the step of forming the baffle comprises a base plate formed in the shape of an annular plate, and a plurality of groove-shaped channels formed in the shape of an annular plate, with openings on the inner and outer circumferences and extending radially, and a plurality of recesses on the outer circumference. The process may be carried out by the following steps: forming a plurality of flow path plates stacked in the thickness direction with the positions of the recesses aligned, and a top plate formed in the shape of a disc sized to close the hollow portion of the flow path plates and having a plurality of recesses formed on its outer circumference, so that their outer diameters match; stacking the base plate, the plurality of flow path plates, and the top plate in this order and positioning them on the same axis, and aligning the positions of the recesses of the flow path plates and the recesses of the top plate; and joining the members together by diffusion bonding while the base plate, the plurality of flow path plates, and the top plate are stacked.

The present invention relates to a method for manufacturing the capacitive pressure sensor, wherein the step of welding the baffle to the housing may be carried out by the steps of: placing the base plate on top of the housing; and sequentially passing laser light through a plurality of grooves formed on the outer circumference of the baffle, extending in the thickness direction and having one end closed by the base plate; and irradiating the portion of the base plate that closes one end of the grooves with laser light to weld this portion to the housing.

The present invention relates to a method for manufacturing the capacitive pressure sensor, and the order in which the grooves through which laser light passes during the step of welding the portion of the base plate that closes the grooves to the housing may be an order in which one groove and the other groove, located on either side of the axis of the baffle, are alternately selected, changing their circumferential position on the baffle.

According to the present invention, since there is no need for welding space around the baffle, it is possible to provide a baffle that enables further miniaturization of the capacitive pressure sensor without compromising performance.
Furthermore, since the numerous components constituting the baffle can be positioned on the same axis with respect to the outer surface, the baffle can be easily manufactured in a single diffusion bonding process.

Figure 1 is a cross-sectional view of the capacitive pressure sensor according to the present invention. Figure 2 shows the base plate of the baffle. Figure 3 shows the top plate of the baffle. Figure 4 shows the flow path plate of the baffle. Figure 5 is a cross-sectional view showing an enlarged view of the main part of a capacitive pressure sensor. Figure 6 is an exploded perspective view of the baffle. Figure 7 is a flowchart illustrating the manufacturing method of a capacitive pressure sensor. Figure 8 is a cross-sectional view showing a method for manufacturing the baffle. Figure 9 is a perspective view of the baffle. Figure 10 shows a baffle. Figure 11 is a perspective view showing the baffle placed on the housing. Figure 12 is a plan view illustrating the welding sequence of laser welding. Figure 13 is a cross-sectional view showing a part of a conventional capacitive pressure sensor.

Hereinafter, an embodiment of the capacitive pressure sensor and the method for manufacturing the capacitive pressure sensor according to the present invention will be described in detail with reference to Figures 1 to 11.
The capacitive pressure sensor 21 shown in Figure 1 is constructed by housing a sensor chip 23, baffles 24, and other components within a housing 22 formed by combining multiple components.

The housing 22 is formed by a lower housing 25 located at the bottom in Figure 1, a cylindrical upper housing 26 welded on top of the lower housing 25, and a cover 27 welded to the open end of the upper housing 26 to close it. Signal transmission electrode terminals 28 pass through the cover 27.
In this embodiment, the lower housing 25 has a structure in which a flange portion 25b is provided at one end of the cylindrical portion 25a. The fluid to be measured is introduced into the lower housing 25 from the other end of the cylindrical portion 25a (the lower side in Figure 1).

The flange portion 25b to which the upper housing 26 of the lower housing 25 is connected is provided with multiple functional parts arranged radially. These functional parts are a circular recess 31 connected to the inner circumference of the cylindrical portion 25a, a flat, annular baffle mounting seat 32 extending radially outward from the opening end of the circular recess 31, and a cylindrical portion 33 projecting cylindrically radially outward from the baffle mounting seat 32. A baffle 24, described later, is welded to the baffle mounting seat 32. The baffle 24 shown in Figure 1 is depicted with its external shape only, omitting its internal structure. The baffle 24 will be described later.

The upper housing 26 is composed of a cylindrical first cylinder 34 welded to the cylindrical portion 33 of the lower housing 25, and a second cylinder 36 welded to the first cylinder 34 with a support diaphragm 35 (described later) sandwiched between them. The first cylinder 34 and the cylindrical portion 33 of the lower housing constitute a peripheral wall 37 surrounding the baffle 24. This peripheral wall 37 becomes the inner wall of the fluid chamber 38 where the baffle 24 is located. A gap S of predetermined interval d is formed between this peripheral wall 37 and the outer surface of the baffle 24 (described later), as shown in Figures 1 and 5. The rupture position of the baffle 24 shown in Figure 1 is along the line I-I drawn on the baffle 24 in Figure 9.

The support diaphragm 35 is formed in an annular plate shape, and its outer circumference is sandwiched between the first cylindrical body 34 and the second cylindrical body 36 and welded to these members. A base plate 41 and a sensor chip 23 are joined to the center of the support diaphragm 35, sandwiching the diaphragm 35. The support diaphragm 35, the base plate 41, and the sensor chip 23 divide the inside of the upper housing 26 into two chambers. Therefore, within the housing 22, a fluid chamber 38 is formed, extending from the hollow portion of the lower housing 25 to the support diaphragm 35, and a vacuum chamber 42 is formed between the support diaphragm 35 and the cover 27. The vacuum chamber 42 is configured to be reduced to a predetermined vacuum level and to maintain that vacuum state.

The fluid to be measured in the fluid chamber 38 is guided to the sensor chip 23 through a through-hole 43 formed in the base plate 41. The sensor chip 23 has a sensor diaphragm 23a that receives the pressure of the fluid to be measured, and is configured to detect the pressure of the fluid based on capacitance. The capacitance data detected by the sensor chip 23 is sent from the sensor chip 23 to a measurement circuit (not shown) via a conductor 44 and the electrode terminals 28 of the cover 27.

The baffle 24 is designed to generate deposits by allowing film formation within the baffle 24 so that the film-forming components in the gas are consumed when a film-forming gas is used as the fluid to be measured. By consuming the film-forming components in the gas within the baffle 24, it is possible to prevent film formation from occurring on the sensor chip 23 and thus prevent a decrease in the performance of the sensor chip 23.
In this embodiment, the baffle 24 divides the fluid chamber 38 into a first fluid chamber 38A at one end into which the fluid to be measured is introduced, and a second fluid chamber 38B at the other end into which the sensor chip 23 is located. The first fluid chamber 38A and the second fluid chamber 38B are connected by a flow path 45 (see Figure 5), which will be described later, within the baffle 24. The flow path 45 is configured such that deposits are generated as the fluid to be measured passes through it. The flow path 45 will be described later.

The baffle 24 is formed by stacking three types of plate-like members. The three types of plate materials are the base plate 51 shown in Figures 2(A) and (B), the top plate 52 shown in Figures 3(A) and (B), and the flow path plate 53 shown in Figures 4(A) to (D). Figure 2(A) is a bottom view of the base plate 51 as seen from the first fluid chamber 38A side, and Figure 2(B) is a cross-sectional view taken along line II-II in Figure 2(A). Figure 3(A) is a plan view of the top plate 52 as seen from the second fluid chamber 38B side, and Figure 3(B) is a cross-sectional view taken along line III-III in Figure 3(A).
Figure 4(A) is a bottom view of the flow path plate 53 as seen from the first fluid chamber 38A side, Figure 4(B) is a bottom view showing an enlarged portion of the flow path plate 53, Figure 4(C) is a plan view of the flow path plate 53 as seen from the second fluid chamber 38B side, and Figure 4(D) is a cross-sectional view taken along line IV-IV in Figure 4(C).

The base plate 51 is a plate that forms one end of the baffle 24, and as shown in Figure 2(A), it is formed in a circular shape when viewed from the thickness direction. Numerous through holes 54 are provided in a circular area with a predetermined diameter in the central part of the base plate 51. For this reason, the base plate 51 is formed in a substantially annular plate shape.
This base plate 51 is placed on the baffle mounting seat 32 of the housing after the baffle 24 is assembled, and its outer circumference is welded to the baffle mounting seat 32 for fixation. This welding is performed by laser welding.

The top plate 52 is a plate that constitutes the other end of the baffle 24, and as shown in Figure 3(A), it is formed in a circular shape when viewed from the thickness direction. The outer diameter of the top plate 52 is equal to the outer diameter of the base plate 51 and the flow path plate 53, which will be described later. On the outer circumference of the top plate 52, semicircular recesses 55 are formed, which are arranged at predetermined intervals in the circumferential direction of the top plate 52 and are connected to the outer edge of the top plate 52. These recesses 55 are provided at positions that divide the top plate 52 into eight equal parts in the circumferential direction.

The flow path plate 53 is a plate for forming the flow path 45. As shown in Figures 4(A) and (C), it is formed in an annular shape with a hollow portion 53a when viewed from the thickness direction, and has numerous radially extending grooves 56. The outer diameter of the flow path plate 53 is the same as the outer diameter of the base plate 51 and top plate 52 described above. The inner diameter of the flow path plate 53 is approximately the same as the diameter of the circular area in the center of the base plate 51 where numerous through holes are provided.
The groove 56 is formed on one side of the flow path plate 53 in the thickness direction, with a depth of approximately 0.1 mm, and the cross-sectional shape when viewed in the radial direction of the flow path plate 53 is rectangular. As shown in Figure 4(B), it extends in a zigzag pattern between the inner and outer circumferences of the flow path plate 53. In Figure 4(B), hatching is applied to the side walls of the groove 56. In this embodiment, the gap S between the peripheral wall 37 of the housing 22 and the baffle 24, the spacing d, is set to be shorter than the depth of the groove 56.

The groove 56 is formed by etching one surface of the flow channel plate 53. One end of the groove 56 opens to the inner circumferential surface of the flow channel plate 53, and the other end opens to the outer circumferential surface of the flow channel plate 53. In this embodiment, the baffle 24 is formed by stacking a number of flow channel plates 53 in the thickness direction such that the axial length is a predetermined dimension. By stacking multiple flow channel plates 53 having grooves 56, the open portions of the grooves 56 are blocked by other flow channel plates 53, forming a flow channel 45.

As shown in Figures 4(A) and (C), multiple recesses 57 are formed on the outer periphery of the flow path plate 53. These recesses 57 are formed in a semicircular shape, connected to the outer edge of the flow path plate 53 when viewed from the thickness direction. In this embodiment, the recesses 57 are provided at positions that divide the flow path plate 53 into eight equal parts in the circumferential direction. Since the outer periphery of the flow path plate 53 has little impact on the flow path design, forming recesses 57 on this outer periphery does not degrade the performance of the baffle 24.

This flow channel plate 53 is used in a state where it is stacked on top of other flow channel plates 53 in the thickness direction to form a multilayer laminate 61 (see Figure 6). The numerous flow channel plates 53 are stacked in the thickness direction and joined together with the base plate 51 and the top plate 52. Figure 6 shows the individual flow channel plates 53 stacked on top of each other to make it easier to understand that the flow channel plates 53 are stacked. Each flow channel plate 53 that makes up the laminate 61 is positioned so that all flow channel plates 53 are on the same axis and the recesses 57 on the outer circumference overlap when viewed from the thickness direction. As a result, eight grooves 62 are formed on the outer circumference of the laminate 61 made up of numerous flow channel plates 53, as the recesses 57 of each flow channel plate 53 are aligned in the thickness direction of the flow channel plate 53.
To form such a laminate 61, a so-called diffusion bonding method is used. The method for forming the laminate 61 of the flow channel plate 53 will be described later.

Next, the method for manufacturing the capacitive pressure sensor 21 according to this embodiment will be described with reference to the flowchart shown in Figure 7. In order to manufacture the capacitive pressure sensor 21, first, in step S1 of the flowchart in Figure 7, the baffle 24 is formed.
To form the baffle 24, first, the base plate 51, the top plate 52, and the numerous flow path plates 53 are formed so that their outer diameters match (step S1A). Then, as shown in Figure 8(A), the base plate 51, the numerous flow path plates 53, and the top plate 52 are stacked in this order on the positioning jig 63 (step S1B). In Figures 8(A) and (B), the thickness of each plate is depicted as thicker than it actually is to make the manufacturing method easier to understand.

As shown in Figure 8(B), the positioning jig 63 positions the base plate 51, the numerous flow path plates 53, and the top plate 52 on the same axis with respect to their outer circumferential surfaces. At this time, the positions of the recesses 57 in the flow path plates 53 and the recesses 55 in the top plate 52 are aligned, so that the recesses 55 and 57 are positioned at the same circumferential position on all plates.

Next, the positioning jig 63 is loaded into a joining device (not shown) and diffusion bonding is performed (step S1C). Diffusion bonding is carried out while the base plate 51, the numerous flow path plates 53, and the top plate 52 are heated to a predetermined temperature, and these components are pressed together in the axial direction to bring them into close contact. Through this diffusion bonding, the base plate 51, the numerous flow path plates 53, and the top plate 52 are joined to each other by diffusion bonding in a stacked state, and the baffle 24 is completed as shown in Figure 9.
When the baffle 24 is completed, as shown in Figure 10(A), the top plate 52 is placed on top of the flow path plate 53, thereby closing the hollow portion 53a of the flow path plate 53 with the top plate 52.

Multiple grooves 62 are formed on the outer circumference of the baffle 24, consisting of recesses 57 in the numerous flow path plates 53 and recesses 55 in the top plate 52. These grooves 62 extend in the stacking direction of each plate. One longitudinal end of the groove 62 is closed by a cover portion 51a, which is the portion of the base plate 51 exposed to the groove 62, as shown in Figure 10(B). The other longitudinal end of the groove is open.

After the baffle 24 is completed, the baffle 24 is welded to the lower housing 25 (step S2).
To perform this welding, first, the baffle 24 is placed on the baffle mounting seat 32 of the lower housing 25 as shown in Figure 5 (step S2A). Then, the laser irradiation unit of a laser welding machine (not shown) is placed above the lower housing 25, and the laser beam L is irradiated onto the groove 62 formed on the outer circumference of the baffle 24 as shown in Figure 11. At this time, the beam incidence angle is set to be close to 90 degrees with respect to the base plate 51 so that the laser beam L is irradiated only onto the lid portion 51a of the base plate 51 which closes one end of the groove 62. When the lid portion 51a is irradiated with the laser beam L, the lid portion 51a is welded to the baffle mounting seat 32 of the lower housing 25.

The laser beam L is sequentially irradiated into eight grooves 62. The order in which the laser beam L is irradiated into the grooves 62 is such that one groove 62 and the other groove 62, located on either side of the axis of the baffle 24, are alternately selected as they change their position in the circumferential direction of the baffle 24. That is, as shown in Figure 12, first, the laser beam L is passed through the first groove 62A and the second groove 62B, located on the first diagonal A of the baffle 24, in this order. Next, the laser beam L is passed through the third groove 62C and the fourth groove 62D, located on the second diagonal B which is perpendicular to the first diagonal L1, in this order. After that, the laser beam L is passed through the fifth groove 62E and the sixth groove 62F, located on the third diagonal C which is tilted at 45 degrees from the second diagonal B, in this order. Then, the laser beam L is passed through the seventh groove 62G and the eighth groove 62H, which are located on the fourth diagonal D, perpendicular to the third diagonal L3, in this order.

By passing the laser beam L through the eight grooves 62 in the order described above and welding the cover portion 51a of each groove 62 to the baffle mounting seat 32, the baffle 24 is welded to the baffle mounting seat 32 so that the entire circumferential area of the baffle 24 is in close contact with the baffle mounting seat 32 (step S2B).
After welding the baffle 24 to the lower housing 25 in this manner, the upper housing 26 is welded to the lower housing 25 to assemble the housing (step S3). In this step, a support diaphragm 35 is welded between the first cylindrical body 34 and the second cylindrical body 36 of the upper housing 26, and the first cylindrical body 34 is welded to the cylindrical portion 33 of the lower housing 25. The base plate 41 and the sensor chip 23 are attached to the support diaphragm 35 in advance.
After welding the upper housing 26 to the lower housing 25, the cover 27 having electrode terminals 28 is welded to the upper housing 26. At this time, the sensor chip 23 and the electrode terminals 28 are electrically connected by a conductor 44.

In the capacitive pressure sensor 21 configured as described above, when the fluid to be measured, such as a film-forming gas, is introduced into the first fluid chamber 38A of the housing 22, this fluid flows into the numerous through-holes 54 formed in the base plate 51 of the baffle 24, as indicated by the arrows in Figure 15. This fluid then enters the flow channels 45 of the numerous flow channel plates 53 from the hollow portion of the baffle 24 and exits the baffle 24 from the outer circumference of the flow channel plates 53. As the fluid passes through the flow channels 45, film-forming components contained in the fluid cause products to adhere to and accumulate on the walls of the flow channels 45.

Therefore, the fluid being measured, after passing through the baffle 24, has a reduced film-forming component. This fluid enters the space between the baffle 24 and the peripheral wall 37 of the housing 22 through the gap S between the baffle 24 and the support diaphragm 35 and base plate 41, and is then guided to the sensor chip 23 through the through hole 43 of the base plate 41. Because the fluid being measured that comes into contact with the sensor chip 23 has a low film-forming component, it is possible to prevent the accumulation of products on the sensor chip 23.

In this embodiment, the baffle 24 is welded to the housing 22 radially inward from its outer edge, eliminating the need for welding space that was previously required. Therefore, the housing 22 can be made smaller compared to conventional designs, enabling further miniaturization of the capacitive pressure sensor without compromising performance.

In this embodiment, the base plate 51, the top plate 52, and the flow path plate 53 are formed to have the same outer diameter. Therefore, an annular passage can be formed between the outer circumferential surface of the baffle 24 and the peripheral wall 37 of the housing 22. The width of this passage, i.e., the gap S between the outer circumferential surface of the baffle 24 and the peripheral wall 37, is constant from one end to the other in the axial direction of the baffle 24. Therefore, the fluid to be measured, flowing out from the outer circumferential surface of the baffle 24, flows smoothly towards the sensor chip 23.

In this embodiment, the gap S between the outer surface of the baffle 24 and the peripheral wall 37 is less than or equal to the depth of the flow path 45 of the flow path plate 53. Therefore, the film-forming components contained in the fluid to be measured that exits from the baffle 24 are more likely to come into contact with the peripheral wall 37 and the outer surface of the baffle 24. As a result, the products adhere to the peripheral wall 37 and the outer surface of the baffle 24, further reducing the film-forming components contained in the fluid to be measured that flows toward the sensor chip 23.
Furthermore, the gap S between the baffle 24 and the peripheral wall 37 is narrower than in the conventional design, and the fluid to be measured flows along the outer surface of the baffle 24, thus shortening the length of the pressure transmission path between the outlet of the flow path 45 of the baffle 24 and the sensor chip 23. As a result, the responsiveness of the sensor chip 23 is improved.

The manufacturing method for the capacitive pressure sensor 21 according to this embodiment includes the steps of forming a stacked baffle 24 (step S1) and welding the baffle 24 to the housing 22 so that the fluid chamber 38 of the housing 22 is partitioned (step S2). The step of forming the baffle 24 (step S1) is carried out by forming a base plate 51, a top plate 52, and a flow path plate 53 so that their outer diameters match (step S1A), stacking the base plate 51, a number of flow path plates 53, and the top plate 52 so that they are located on the same axis and aligning the recesses 55 and 57 (step S1B), and joining the members together by diffusion bonding while the base plate 51, the number of flow path plates 53, and the top plate 52 are stacked.
Therefore, when manufacturing the baffle 24, which consists of a base plate 51, numerous flow path plates 53, and a top plate 52, diffusion bonding only needs to be performed once. Consequently, a high-quality laminated baffle can be easily manufactured.

In this embodiment, the step of welding the baffle 24 to the housing is performed by step S2A, which involves stacking the base plate 51 on the housing 22, and step S2B, which involves sequentially passing laser light L through a plurality of grooves 62 formed on the outer circumference of the baffle 24, and irradiating the cover portion 51a that closes one end of the grooves 62 in the base plate 51 with the laser light L to weld this cover portion 51a to the housing 22. Therefore, the cover portion 51a, which is a narrow and limited part of the base plate 51, can be accurately welded to the baffle mounting seat 32 by laser welding. By setting the incidence angle of the laser beam to be close to 90 degrees with respect to the base plate 51, as in this embodiment, the recesses 55 and 57 formed in the top plate 52 and the flow path plate 53 can be reduced, making it possible to maximize the effective flow path range of the baffle 24.

In step S2B, where the cover portion 51a that closes the groove 62 of the base plate 51 is welded to the housing 22, the order in which the laser beam L passes through the grooves 62 is such that one groove 62 and the other groove 62, positioned on either side of the axis of the baffle 24, are alternately selected, changing the circumferential position of the baffle 24. Therefore, even if the baffle 24 is simply placed on the baffle mounting seat 32 by its own weight, the entire circumferential area of the base plate 51 will be in close contact with the baffle mounting seat 32 after welding. Consequently, welding of the baffle 24 to the housing 22 can be performed easily and accurately.

21…Capacitive pressure sensor, 22…Housing, 23…Sensor chip, 24…Baffle, 37…Peripheral wall, 38…Fluid chamber, 38A…First fluid chamber (one end), 38B…Second fluid chamber (other end), 45…Flow path, 51…Base plate, 51a…Lid, 52…Top plate, 53…Flow path plate, 53a…Hollow section, 62…Groove, S…Gap, S1…Step of forming the baffle, S1B…Step of stacking the base plate, multiple flow path plates, and top plate to align the recesses, S1C…Step of joining the base plate, multiple flow path plates, and top plate to each other by diffusion bonding, S2…Step of welding the baffle, S2A…Step of stacking the base plate on the housing, S2B…Step of welding the lid of the base plate to the housing.

Claims (6)

A housing having a fluid chamber into which the fluid to be measured is introduced,
A sensor chip for detecting the pressure of the fluid to be measured in the fluid chamber,
The fluid chamber is divided into one end where the fluid to be measured is introduced and the other end where the sensor chip is located, and a baffle connects the one end and the other end by a flow path through which deposits are generated as the fluid to be measured passes.
The aforementioned baffle is
A number of channel plates are formed in an annular plate shape, with numerous groove-shaped channels extending radially and opening at the inner and outer circumferences, and are stacked in the thickness direction and joined to one another.
A base plate formed in the shape of an annular plate and joined to one end in the stacking direction of the numerous flow channel plates,
The system comprises a top plate joined to the other end of the aforementioned number of flow path plates in the stacking direction, which closes the hollow portion of the flow path plate.
Multiple grooves extending in the stacking direction are formed on the outer periphery of the baffle.
One end of the groove in the longitudinal direction is closed by the base plate, while the other end is open.
A capacitive pressure sensor characterized in that the portion of the base plate exposed to the groove is welded to the housing. In the capacitive pressure sensor according to claim 1,
A capacitive pressure sensor characterized in that the flow path plate, the base plate, and the top plate are formed so that their outer diameters match. In the capacitive pressure sensor according to claim 1,
The inner wall of the fluid chamber in which the baffle is arranged is formed by a peripheral wall that has a predetermined gap between it and the outer surface of the baffle.
A capacitive pressure sensor characterized in that the gap is less than or equal to the depth of the groove-shaped flow path. The steps include forming a stacked baffle having a channel through which deposits are generated as the fluid to be measured passes,
The method includes the step of welding a baffle to a housing having a fluid chamber into which the fluid to be measured is introduced at one end, and a sensor chip for detecting the pressure of the fluid to be measured in the fluid chamber is provided at the other end, such that the one end and the other end are separated and the one end and the other end are in communication through the flow path,
The step of forming the baffle is,
A base plate formed in the shape of an annular plate,
A plurality of flow path plates are formed in an annular plate shape, with numerous groove-shaped flow paths extending radially and opening in the inner and outer circumferences, and multiple recesses in the outer circumference, and are stacked in the thickness direction with the positions of the recesses aligned.
The steps include forming a top plate that is shaped like a disc and has multiple recesses formed on its outer circumference, so that their outer diameters match, and the top plate is shaped to close the hollow portion of the flow channel plate,
The steps include stacking the base plate, the numerous flow path plates, and the top plate in this order and positioning them on the same axis, and aligning the positions of the recesses in the flow path plates and the recesses in the top plate,
A method for manufacturing a capacitive pressure sensor, characterized by the step of joining the components together by diffusion bonding while the base plate, a number of flow path plates, and the top plate are stacked. In the method for manufacturing a capacitive pressure sensor according to claim 4,
The step of welding the baffle to the housing is,
The steps include: placing the base plate on the housing,
A method for manufacturing a capacitive pressure sensor, characterized by passing laser light sequentially through a plurality of grooves formed on the outer circumference of the baffle, extending in the thickness direction and having one end closed by the base plate, and irradiating the portion of the base plate that closes one end of the grooves with laser light and welding this portion to the housing. In the method for manufacturing a capacitive pressure sensor according to claim 5,
In the step of welding the portion of the base plate that closes the groove to the housing, the order of the grooves through which the laser light passes is:
A method for manufacturing a capacitive pressure sensor, characterized in that one groove and the other groove, which are positioned on either side of the axis of the baffle, are selected in an alternating order that changes the circumferential position of the baffle.