JP2024029841A - pressure sensor - Google Patents

Abstract

To provide a pressure sensor with which it is possible to measure the pressure of a pressure medium at higher temperature with good accuracy.SOLUTION: Provided is a pressure sensor 1 that is used for semiconductor manufacturing devices, said sensor comprising a hollow and cylindrical housing 2, a first base 3 provided at one end of the housing 2, a second base 4 provided at the other end of the housing 2, a diaphragm 5a that is supported to the first base 3 and is elastically deformed upon receiving pressure P, a sensor unit 6 that is supported to the second base 4 and detects, and converts to an electric signal, the stress due to the elastic deformation of the diaphragm 5a, a rod pin 7 that is provided penetrating the first base 3 and second base 4 between the diaphragm 5a and the sensor unit 6, and a first slide member 10 that is provided between the outer surface of the second base 4 and the inner circumferential surface of the housing 2. The rod pin 7 is formed from a metal material whose coefficient of thermal linear expansion at 30°C to 100°C is 1.3×10-6/°C or smaller.SELECTED DRAWING: Figure 1

Description

The present invention relates to a pressure sensor, and more particularly to a pressure sensor that is used in semiconductor manufacturing equipment and measures the pressure of a high-temperature pressure medium.

2. Description of the Related Art Pressure sensors have been used to measure the pressure of liquids and gases in various fields such as semiconductor manufacturing equipment, automobiles, and medical equipment. When the medium to be measured reaches a very high temperature, it is important that the pressure sensor has a structure that can withstand high temperatures.

For example, pressure sensors are known for measuring the pressure of high-temperature pressure media such as various special gases used in semiconductor manufacturing processes. In particular, important steps in the semiconductor manufacturing process include forming an insulating film such as _SiO2 on the surface of a silicon wafer in a diffusion furnace, and vapor deposition to form a thin film on a silicon substrate using CVD (chemical vapor deposition). There is a process using the method. Further, these steps include a step in which a raw material gas containing a thin film component is supplied to a reaction vessel in a thermal oxidation device or a CVD device, and a film is deposited on the substrate surface by a chemical reaction.

In recent years, in order to shorten the elapsed time of these time-consuming film forming steps, a method has been used in which the temperature inside the container and the temperature of the supplied gas are increased to increase the chemical reaction rate of the gas. In semiconductor manufacturing equipment used in such semiconductor manufacturing processes, there is a demand for pressure sensors used for process control to be heat resistant, and in particular, to develop pressure sensors that have heat resistance of 250° C. or higher.

However, conventional pressure sensors may be difficult to use when the temperature of the pressure medium exceeds 180°C. For example, in a pressure sensor equipped with a metal strain gauge using CrNi material, the temperature of the pressure medium is limited to 150°C. In addition, general Si semiconductor strain gauges have large temperature drifts and become unstable at temperatures above 100° C., making them difficult to use. In addition, strain gauges using SiC have been developed, but the wiring used inside them becomes unusable because the coating carbonizes at 180°C to 250°C. Furthermore, the electronic circuit attached to the pressure sensor is damaged when exposed to high temperature parts, so it must be isolated from the pressure-receiving part to which pressure is applied in the pressure sensor.

Therefore, a sensor structure has been proposed in which the pressure detection element of the pressure sensor is isolated from the pressure receiving part which becomes high temperature, and the temperature of the pressure detection element is lowered to, for example, 100 degrees Celsius or less. For example, Non-Patent Document 1 discloses that a coiled thin tube filled with silicone oil is used between the pressure receiving part and the pressure sensing element to transmit displacement to the pressure sensing element isolated from the pressure receiving part in a high temperature environment. A pressure sensor is disclosed. In the pressure sensor described in Non-Patent Document 1, the heat from the pressure receiving part that is received by the silicone oil filled in the thin tube is cooled by air through the space provided between the pressure receiving part and the pressure detecting element, and the heat from the pressure receiving part is transferred to the pressure detecting element side. By reducing the influence of heat on the air, pressure can be measured in high-temperature environments.

However, the pressure sensor described in Non-Patent Document 1 has a structure that uses silicone oil as a pressure transmission medium, and the heat resistance of the pressure sensor is limited because the silicone oil has a heat resistance temperature of 250°C. In particular, at a heating temperature of 250° C. or higher, silicone oil boils and vapor pressure is generated, resulting in measurement errors.

In addition, in the pressure sensor described in Non-Patent Document 1, the metal container and metal capillary of the pressure sensor expand in proportion to the increase in heating temperature, and press against the diaphragm of the pressure detection element on the end face of the capillary. Become. In other words, the expansion stress of the capillary due to the pressure transmission stress and temperature rise, and the pressure displacement stress of the heat-resistant silicone oil become a combined stress that pushes up the diaphragm of the pressure detection element, so the measurement error at high temperatures becomes larger. .

Furthermore, in the pressure sensor described in Non-Patent Document 1, it is necessary to take a relatively long distance between the pressure receiving part and the pressure detection element for air cooling, and by using a coiled thin tube, The distance between the part and the pressure sensing element becomes even longer. Therefore, the speed of pressure transmission from the pressure receiving section to the pressure detection element becomes slow.

As another example of a conventional sensor structure that isolates the pressure sensing element of a pressure sensor from a pressure receiving part that becomes high temperature and lowers the temperature of the pressure sensing element, Patent Document 1 discloses a method in which a rod pin is installed between the pressure receiving part and the pressure sensing element. The present invention discloses a pressure sensor having a structure in which a rod pin transmits the pressure of a pressure receiving part to a pressure detection element.

However, in the pressure sensor described in Patent Document 1, the metal container of the pressure sensor can withstand a heating temperature of, for example, 300° C., but the metal such as stainless steel used for the metal container has a relatively large thermal expansion. Furthermore, since metal such as stainless steel is used for the rod pin, the coefficient of thermal expansion is relatively large. Both the metal container and the rod pin of the pressure sensor expand thermally as the heating temperature rises, and press the center of the pressure sensing element as stress. Therefore, the combined stress of pressure stress and thermal expansion stress is transmitted to the detection surface of the pressure detection element, causing an error in the measured pressure.

Japanese Patent Application Publication No. 4-290937

Keller Publishing, “Series 35XHTC Data Sheet”, [online], September 15, 2020, [searched on June 27, 2020], Internet <https://download. keller-druck. com/api/download/hH7qKyYHH2gDhU7CPqeCgX/en/2020-09. pdf>

According to conventional techniques, it has been difficult to accurately measure the pressure of a pressure medium at a higher temperature.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a pressure sensor that can accurately measure the pressure of a pressure medium at a higher temperature.

In order to solve the above problems, a pressure sensor according to the present invention is a pressure sensor used in semiconductor manufacturing equipment, and includes a hollow cylindrical housing and a first base provided on one end side of the housing. a second base provided at the other end of the housing; a diaphragm supported by the first base and elastically deformed when subjected to pressure; a pressure detection element that detects stress caused by deformation and converts it into an electrical signal; and a pressure transmission member that penetrates the first base and the second base and is provided between the diaphragm and the pressure detection element. , a first sliding member provided between the outer surface of the second base and the inner circumferential surface of the housing, and the pressure transmission member has a linear thermal expansion coefficient of 1.3 from 30° C. to 100° C. It is characterized by being formed of a metal material with a temperature of ×10 ⁻⁶ /°C or less.

Further, in the pressure sensor according to the present invention, each of the first base and the second base is formed with a through hole along the central axis in the longitudinal direction of the housing, and the pressure transmitting member is connected to the It may be inserted into a through hole and provided along the central axis.

The pressure sensor according to the present invention further includes a plurality of columns provided between the first base and the second base, the plurality of columns extending around the pressure transmission member. It may be provided in parallel to the central axis at a position spaced apart from the central axis so as to surround the central axis.

Moreover, in the pressure sensor according to the present invention, one end of the pressure transmission member may be welded to the diaphragm, and the other end of the pressure transmission member may be welded to the detection surface of the pressure detection element.

Moreover, in the pressure sensor according to the present invention, the pressure transmitting member may be formed of a super invar material.

Furthermore, in the pressure sensor according to the present invention, the first sliding member may be formed of a material containing a fluororesin, which has a relatively low thermal conductivity among resin materials.

Further, in the pressure sensor according to the present invention, the pressure transmission member may be configured to be splittable in the longitudinal direction, and the divided portion may be configured so that the length in the longitudinal direction of the pressure transmission member is adjustable. good.

Moreover, in the pressure sensor according to the present invention, the plurality of support columns may be formed of a super invar material.

Furthermore, in the pressure sensor according to the present invention, a support plate is provided between the first base and the second base and supports the plurality of support columns and the pressure transmission member; a second sliding member disposed between the housing and the inner circumferential surface of the housing, the second sliding member being made of a material containing a fluororesin and having a relatively low thermal conductivity among resin materials. may have been done.

According to the present invention, the pressure transmission member penetrates through the first base and the second base and is provided between the diaphragm and the pressure detection element, and the pressure transmission member is connected between the outer surface of the second base and the inner circumferential surface of the housing. The pressure transmitting member is made of a metal material having a linear thermal expansion coefficient of 1.3×10 ⁻⁶ /°C or less in the range from 30° C. to 100° C. Therefore, it is possible to accurately measure the pressure of a pressure medium at a higher temperature.

FIG. 1 is a diagram showing the main parts of a pressure sensor according to an embodiment of the present invention, in which (a) is a schematic cross-sectional view, and (b) is a schematic plan view taken in the direction of arrow A in (a). FIG. 2 is an exploded perspective view of the main body of the pressure sensor according to this embodiment. FIG. 3 is a diagram showing an example of the structure of the housing of the pressure sensor according to the present embodiment, in which (a) is a front view and (b) is a schematic plan view as viewed from arrow A. FIG. 4 is a diagram for explaining the material of the rod pin of the pressure sensor according to the present embodiment. FIG. 5A is a diagram for explaining the material of the rod pin of the pressure sensor according to the present embodiment. FIG. 5B is a diagram for explaining the material of the rod pin of the pressure sensor according to this embodiment. FIG. 5C is a diagram for explaining the material of the rod pin of the pressure sensor according to this embodiment. FIG. 6 is a diagram for explaining the influence of thermal expansion on the pressure sensor according to this embodiment.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to FIGS. 1 to 6.
[Embodiment]
First, an overview of a pressure sensor 1 according to an embodiment of the present invention will be explained. FIG. 1(a) is a schematic sectional view of a main part of a pressure sensor 1 according to an embodiment of the present invention, and FIG. 1(b) is a schematic plan view of the pressure sensor 1 in the direction of arrow A. FIG. 2 is an exploded perspective view of the main body of the pressure sensor 1 according to the embodiment of the invention. The pressure sensor 1 is provided in a semiconductor manufacturing apparatus, and measures the pressure P of a pressure medium, such as a gas, at a temperature of, for example, 250° C. or higher.

As shown in FIG. 1(a), the pressure sensor 1 mainly includes a housing 2, a pressure receiving part 5, and a sensor part (pressure detection element) 6, and inside the hollow cylindrical housing 2, A first base 3, a second base 4, a rod pin (pressure transmission member) 7, columns 8a, 8b, 8c, and a support plate 9 are accommodated. Pressure P applied to the pressure receiving section 5 is transmitted to the sensor section 6 by the rod pin 7.

In addition, in the following, the structure of the pressure sensor 1 excluding the housing 2, that is, the first base 3, the second base 4, the pressure receiving part 5, the sensor part 6, the rod pin 7, the columns 8a, 8b, 8c, and the support plate. 9, the structure including the first sliding member 10 and the second sliding member 11 is referred to as the main body of the pressure sensor 1. Further, in the pressure sensor 1 according to the present embodiment, each structure of the main body portion and the housing 2 are sequentially connected and integrated by welding, adhesion, or the like.

The housing 2 is formed into a cylindrical shape having a hollow portion with a circular cross section that penetrates in the direction of the axis O. Openings are formed at both ends of the housing 2, and a pressure receiving part 5 that receives pressure P applied from the outside is provided at one end. The other end of the housing 2 is provided with a sensor section 6 that detects stress caused by elastic deformation of the diaphragm 5a in the pressure receiving section 5 and converts it into an electrical signal. The length of the housing 2 in the longitudinal direction is set according to the temperature of the pressure P to be measured. Note that, hereinafter, the longitudinal axis O of the housing 2 may be referred to as the axis O of the pressure sensor 1.

The housing 2 is made of a metal material with high thermal conductivity, such as aluminum. For example, the outer peripheral surface of the housing 2 may have a structure in which a plurality of fins are formed to expand the heat transfer area in order to radiate heat from the pressure receiving part 5. FIG. 3(a) shows a front view of the housing 2 having an outer circumferential surface with a fin structure formed thereon, and FIG. 3(b) shows a front view of the housing 2 having an outer circumferential surface with a fin structure formed thereon as viewed from arrow A. A plan view is shown. By configuring the housing 2 in this manner, it is possible to efficiently radiate heat from the pressure receiving part 5 exposed to high temperatures, and to suppress fluctuations in the temperature inside the housing 2 in which the main body part is housed. .

For example, when measuring the pressure P at a high temperature of 300° C., the length of the housing 2 in the longitudinal direction can be 145 [mm] and the length in the radial direction can be 50 [mm]. The length of the housing 2 in the longitudinal direction, that is, the distance between the pressure receiving part 5 and the sensor part 6 in the main body of the pressure sensor 1 is set according to the temperature of the pressure P to be measured. For example, when the temperature of the pressure P to be measured is lower than 300° C., the length of the housing 2 in the longitudinal direction can be made shorter.

The first base 3 is provided on one end side of the housing 2, that is, on the pressure receiving part 5 side. The first base 3 is formed into a substantially cylindrical column with a circular cross section and a diameter that substantially matches the inner diameter of the housing 2 . The first base 3 supports the pressure receiving part 5 on one bottom surface 3a side. Further, the other bottom surface 3b of the first base 3 faces the hollow side of the housing 2.

A through hole 3c is formed in the first base 3 along the axis O from the bottom surface 3a to the other bottom surface 3b. The diameter of the through hole 3c is slightly larger than the diameter of a rod pin 7, which will be described later. Note that a protruding structure is formed along the axis O direction on the outer edge portion of the bottom surface 3a. Due to the protruding structure of the bottom surface 3a, a recess toward the inside of the first base 3 is formed in the area around the axis O. This concave structure forms a space that allows the diaphragm 5a of the pressure receiving part 5 to bend due to the pressure P.

Further, a protrusion lower than the protrusion structure on the outer edge portion is formed so as to surround an even narrower area around the axis O on the bottom surface 3a, and functions as a stopper that defines the maximum deflection that the diaphragm 5a of the pressure receiving part 5 can receive. . Further, on the bottom surface 3b side of the first base 3, one end portion of pillars 8a, 8b, and 8c, which will be described later, is fixedly supported. The first base 3 is made of a metal material such as stainless steel (SUS304). The first base 3, the housing 2, and the pressure receiving part 5 are each fixedly joined by welding or the like.

The second base 4 is provided on the other end side of the housing 2, that is, on the sensor section 6 side. The second base 4 is formed into a substantially cylindrical shape having a circular cross section with a diameter slightly smaller than the inner diameter of the housing 2 . The second base 4 supports the sensor section 6 on one bottom surface 4a side. Further, the other bottom surface 4b of the second base 4 faces the hollow side of the housing 2.

A through hole 4c is formed in the second base 4 along the axis O from the bottom surface 4a to the other bottom surface 4b. The diameter of the through hole 4c can be slightly larger than the diameter of a rod pin 7, which will be described later, and can be made equal to the diameter of the through hole 3c formed in the first base 3.

Further, on the bottom surface 4b side of the second base 4, three non-through holes 4d are formed in which the other end portions of pillars 8a, 8b, and 8c, which will be described later, are supported. The diameter of this non-through hole 4d can be made slightly larger than the diameter of the pillars 8a, 8b, and 8c. In addition, the depth of the non-through hole 4d in the axis O direction is determined by the space between the other end of the pillars 8a, 8b, and 8c and the non-through hole 4d, as shown in FIG. 1(a). be deep enough so that a Note that details of the play space of the non-through hole 4d will be described later.

The second base 4 is made of a metal material such as stainless steel. The second base 4 and the sensor part 6 are fixedly joined by welding or the like, but the second base 4 and the housing 2 are connected to each other via a first sliding member 10, which will be described later. 4 is provided so as to be slidable in the direction of the axis O with respect to the housing 2.

The pressure receiving part 5 includes a pressure receiving diaphragm 5a that elastically deforms when pressure P is applied. The diaphragm 5a has one side exposed to the outside as a pressure receiving surface. This pressure receiving surface bends and deforms in response to external pressure P as the pressure to be measured, and is attached to an end surface 7a of a rod pin 7, which will be described later, which is fixedly joined to the center area of the other surface of the diaphragm 5a in the direction of the axis O. Apply a force of

The pressure receiving part 5 is made of stainless steel such as SUS316, for example. Further, as shown in FIG. 1B, the diaphragm 5a is formed of a disc-shaped stainless steel thin film, and its center point coincides with the axis O of the pressure sensor 1.

The sensor section 6 has a structure in which a diaphragm 6a and a signal processing section 6b are housed in a case member 6c. The sensor section 6 can have a sensor structure based on, for example, a strain resistance type, a capacitance type, a piezoelectric element type, or the like. For example, in the strain resistance type, the diaphragm 6a can form a strain resistance bridge circuit in a metal thin film such as stainless steel, a ceramic thin film, or a silicon (Si) thin film.

The center point of the diaphragm 6a coincides with the axis O of the pressure sensor 1. One surface of the diaphragm 6a serves as a detection surface for detecting stress due to the pressure P transmitted by the rod pin 7, and the other end surface 7b of the rod pin 7, which will be described later, is fixedly joined. For example, the other end surface 7b of the rod pin 7 can be fixed to the central point area of the diaphragm 6a with an adhesive such as an epoxy resin adhesive. A gauge resistor (not shown) is arranged on the other surface of the diaphragm 6a, which is opposite to the surface to which the rod pin 7 is joined, and the resistance value of the gauge resistor, which changes with the stress of the pressure P transmitted by the rod pin 7, is detected. be done.

A holding ring 6e is provided between the diaphragm 6a and the signal processing section 6b. By providing the holding ring 6e, the position of the diaphragm 6a along the axis O is fixed, so when the end face 7b of the rod pin 7 presses the center of the diaphragm 6a, the pressure displacement of the diaphragm 5a of the pressure receiving part 5 is ensured. can be transmitted to.

The signal processing section 6b converts the resistance value of the gauge resistance detected in the diaphragm 6a into a voltage signal proportional to the pressure P. More specifically, the signal processing unit 6b performs known signal processing including amplification, AD conversion, noise removal, etc. of the electrical signal indicating the pressure P, and outputs the signal to the outside. Note that the signal processing section 6b is provided with a terminal (not shown) for connecting the pressure sensor 1 to an external electronic device, and a signal line 6d (see FIG. 2) to which the sensor output is supplied is connected to this terminal. Ru.

The rod pin 7 is a rod-shaped member that penetrates the first base 3 and the second base 4 and is provided between the pressure receiving part 5 and the sensor part 6. More specifically, one longitudinal end surface 7a of the rod pin 7 is joined to the diaphragm 5a of the pressure receiving section 5, and the other end surface 7b is also joined to the diaphragm 6a of the sensor section 6. It is inserted into the through hole 3c of the first base 3 and the through hole 4c of the second base 4.

The diameter of the rod pin 7 is smaller than the diameter of the through holes 3c and 4c so that a certain space is formed that does not touch the through holes 3c of the first base 3 and the through holes 4c of the second base 4. It can be done. Further, the axis of the rod pin 7 coincides with the axis O of the pressure sensor 1. In this way, the rod pin 7 is inserted into the through holes 3c and 4c of the first base 3 and the second base 4, and is provided between the pressure receiving part 5 and the sensor part 6 along the axis O. , the pressure P applied to the pressure receiving section 5 can be transmitted to the sensor section 6.

Further, as shown in FIG. 2, the rod pin 7 is configured to be splittable in the longitudinal direction, and the split portion has an adjuster portion 7c that allows the length of the rod pin 7 in the longitudinal direction to be adjusted. For example, the adjuster portion 7c is configured by a female screw structure formed at one end of the rod pin 7 divided into two, and a male screw structure that fits into this female screw structure formed at the other end.

By adopting a structure in which the rod pin 7 can be divided, when manufacturing the pressure sensor 1, after joining the end surfaces 7a and 7b of the rod pin 7 to the diaphragms 5a and 6a, respectively, the rod pin 7 divided into two parts is attached to the adjuster. They can be joined at the portion 7c. Note that the length of the rod pin 7 in the longitudinal direction is determined according to the separation distance between the pressure receiving part 5 and the sensor part 6, which is necessary for air cooling of the main body part heated by the pressure medium measured by the pressure sensor 1. Ru.

The rod pin 7 is made of a metal material such as Super Invar, which has a low coefficient of thermal expansion near room temperature, particularly a coefficient of linear thermal expansion of 1.3×10 ⁻⁶ /° C. or less between 30° C. and 100° C. Super Invar is an alloy of iron, nickel, and cobalt. FIG. 4 is a bar graph showing representative values of linear thermal expansion coefficients of various metal materials. In FIG. 4, the vertical axis is hatched according to the temperature conditions (normal temperature 30° C. to 100° C., −20° C. to 60° C.). 5A to 5C are diagrams each showing representative values of linear thermal expansion coefficients of various metal materials in a table format.

As shown in Figure 5, Super Invar is a metal material that has a coefficient of linear thermal expansion that is 1/35 of that of stainless steel (SUS304), and its coefficient of linear thermal expansion is lower than that of other metal materials. and extremely low. Therefore, by forming the rod pin 7 from Super Invar, a pressure transmission member that is not affected by stress due to thermal linear expansion of the rod pin 7 itself can be realized.

End surfaces 7a and 7b of the rod pin 7 can be fixedly joined to the diaphragm 5a of the pressure receiving section 5 and the diaphragm 6a of the sensor section 6, respectively, by welding, adhesive, or the like.

The pillars 8a, 8b, and 8c are elongated cylindrical members provided between the first base 3 and the second base 4. More specifically, the columns 8a, 8b, and 8c are provided between the first base 3 and the second base 4, passing through the support plate 9. The diameters of the struts 8a, 8b, and 8c can be made equal to the diameter of the rod pin 7. Further, when the housing 2 is viewed from the direction of arrow A, the struts 8a, 8b, and 8c are arranged parallel to the axis O at positions spaced a certain distance from the rod pin 7 on the axis O so as to surround the rod pin 7. It is set up so that

The struts 8a, 8b, and 8c are made of a metal material such as Super Invar, which has a low coefficient of thermal expansion near room temperature, in particular, a coefficient of linear thermal expansion of 1.3×10 ^-6 /°C or less between 30°C and 100°C. can be formed. By forming the struts 8a, 8b, and 8c from Super Invar, which has an extremely low coefficient of thermal expansion, similarly to the rod pin 7, thermal expansion of not only the rod pin 7 but the entire main body can be suppressed.

One longitudinal end of each of the columns 8a, 8b, and 8c is fixedly joined to the first base 3, respectively. The other ends of the columns 8a, 8b, and 8c are respectively inserted into the non-through holes 4d of the second base 4, and are provided movably in the direction of the axis O with respect to the second base 4. More specifically, there is a play space between the other end of the pillars 8a, 8b, 8c and the bottom surface of the non-penetrating hole 4d, which allows the pillars 8a, 8b, 8c to move along the axis O direction. It is formed.

The support plate 9 is arranged between the first base 3 and the second base 4 in the hollow part of the housing 2 . The support plate 9 can be arranged, for example, at a position that is half the length from the first base 3 to the second base 4 along the axis O. The support plate 9 is formed into a substantially cylindrical shape having a circular cross section with a diameter that substantially matches the inner diameter of the housing 2 . The center point of the circular cross section of the support plate 9 coincides with the axis O. A through hole 9a is formed in the direction of the axis O of the support plate 9, and the rod pin 7 is inserted into this through hole 9a. The through hole 9a has the same diameter as the through holes 3c and 4c of the first base 3 and the second base 4, and is slightly larger than the diameter of the rod pin 7.

The support plate 9 is further formed with through holes through which each of the pillars 8a, 8b, and 8c is inserted. The through holes through which the pillars 8a, 8b, and 8c are inserted can have a diameter large enough to contact the pillars 8a, 8b, and 8c without any gaps.

The support plate 9 and the pillars 8a, 8b, and 8c are each fixedly joined. On the other hand, the support plate 9 and the housing 2 are slidably arranged via a second sliding member 11, which will be described later. Specifically, the support plate 9 is arranged so as to be slidable in the direction of the axis O with respect to the housing 2. The support plate 9 is made of a metal material such as stainless steel. By providing the support plate 9, the main body including the rod pin 7 is more stably supported within the housing 2, but it may be omitted.

The first sliding member 10 is a film-like member provided between the side surface (outer surface) of the second base 4 and the inner peripheral surface of the housing 2 . The first sliding member 10 is provided so as to cover the entire side surface of the second base 4. The first sliding member 10 is made of, for example, fluororesin (Teflon (registered trademark)), which has a small coefficient of friction and good sliding properties, and has a relatively high thermal conductivity compared to, for example, other resin materials. Made of low quality material.

The second sliding member 11 is a film-like member provided between the side surface of the support plate 9 and the inner peripheral surface of the housing 2 . The second sliding member 11 is provided so as to cover the entire side surface of the support plate 9. Similarly to the first sliding member 10, the second sliding member 11 is also made of fluororesin or the like.

Here, with reference to the schematic sectional views of the pressure sensor 1 before and after the high temperature pressure P is applied, shown in FIGS. 6(a) and 6(b), thermal expansion in the housing 2 and the main body will be Explain the impact. FIG. 6A shows a schematic cross-sectional view of the pressure sensor 1 before the pressure P is applied to the pressure receiving part 5. FIG. 6(b) shows a schematic cross-sectional view of the pressure sensor 1 when the pressure P is applied to the pressure receiving part 5.

When pressure P such as high-temperature gas is applied to the pressure receiving part 5, the housing 2 made of a metal material such as aluminum thermally expands and extends in the direction of the axis O, as shown in FIG. 6(b). do. Specifically, the housing 2 made of aluminum has excellent thermal conductivity but has a high coefficient of linear thermal expansion. It extends by a length d from the previous length h in the direction of the axis O due to thermal expansion. On the other hand, since the pressure receiving part 5 made of stainless steel is joined to the housing 2 which functions as a heat dissipation material, when exposed to high temperatures, the heat of the pressure receiving part 5 is radiated through the housing 2, and the pressure receiving part 5 is Thermal expansion of portion 5 is suppressed.

Next, since the first base 3 supporting the pressure receiving part 5 is in direct contact with the housing 2 which functions as a heat dissipating material, thermal expansion can be suppressed to some extent. However, as shown in FIGS. 6A and 6B, after the pressure P is applied, the first base 3 extends by a length b in the direction of the axis O due to thermal expansion.

As described above, one end of each of the columns 8a, 8b, and 8c is fixedly joined to the first base 3. Therefore, when the first base 3 expands in the direction of the axis O due to thermal expansion, the columns 8a, 8b, and 8c are also pushed up in the direction of the axis O together with the first base 3. However, as shown in FIG. 6(b), the other ends of the supports 8a, 8b, and 8c only move in the direction of the axis O within the non-through hole 4d. That is, the other ends of the supports 8a, 8b, and 8c do not touch the bottom surface of the non-through hole 4d and push up the second base 4.

In this way, the play space of the non-through hole 4d absorbs the length of the first base 3 due to thermal expansion, so the second base 4 can absorb the influence of the linear thermal expansion of the first base 3. I don't receive it. Incidentally, since the struts 8a, 8b, and 8c are formed of super invar as described above, the thermal linear expansion of the struts 8a, 8b, and 8c themselves does not affect them.

Next, focusing on the rod pin 7, when a high temperature pressure P is applied to the pressure receiving part 5, the diaphragm 5a is deflected by the pressure P, and stress is transmitted to the rod pin 7. Further, the rod pin 7 transmits the pressure P to the diaphragm 6a of the sensor section 6. As mentioned above, the rod pin 7 is made of Super Invar, which is a material with a low coefficient of linear thermal expansion, so even when transmitting high-temperature pressure P, there is almost no elongation in the direction of the axis O due to heat ( The length r) in FIGS. 6(a) and 6(b).

Note that the diaphragm 5a of the pressure receiving part 5 is formed of an extremely thin metal thin film, and the coefficient of linear thermal expansion of the diaphragm 5a itself is extremely small, so that expansion in the direction of the axis O due to heat is extremely small. Therefore, the influence of thermal linear expansion of the diaphragm 5a on the rod pin 7 is extremely small.

In other words, when a high temperature pressure P is applied, the housing 2 expands in the direction of the axis O due to thermal expansion, whereas the main body including the rod pin 7 and supports 8a, 8b, 8c with low thermal expansion expands in the direction of the axis O due to heat. There is almost no elongation in the O direction. Further, the expansion in the direction of the axis O due to thermal expansion of the first base 3 included in the main body portion is absorbed by the non-through hole 4d of the second base 4. That is, the main body has a structure that can suppress the influence of linear thermal expansion of the first base 3.

Further, in the main body of the pressure sensor 1, the first base 3, the second base 4, and the support plate 9 are the surfaces that contact the housing 2, and the second base 4 and the support plate 9 are It is in contact with the inner circumferential surface of the housing 2 via a first sliding member 10 and a second sliding member 11 arranged so as to cover the side surface. The inner peripheral surface of the housing 2 in contact with the first sliding member 10 and the second sliding member 11 becomes a sliding surface, and the housing 2 extends in the direction of the axis O relative to the main body.

Specifically, as shown in FIGS. 6(a) and 6(b), the position of the second base 4 and the support plate 9 in the axis O direction after the application of the high temperature pressure P is such that the housing 2 is aligned with the axis O. While the rod pin 7 is expanding in the direction (from the length h to the length h'), the position corresponding to the length r of the rod pin 7 is maintained. In this way, the main body on which the rod pin 7 is supported comes into contact with the housing 2 via the first sliding member 10 and the second sliding member 11, so that the thermal expansion of the housing 2 and the thermally stationary rod pin 7 It is possible to absorb the difference in thermal linear expansion displacement (length d) between

In this way, the rod pin 7, which is a pressure transmitting member, has a floating structure that is housed in the housing 2 but is thermally isolated from the housing 2. Since the rod pin 7 has such a floating structure, stress due to thermal expansion of the housing 2 is not transmitted by the rod pin 7.

Further, by forming not only the rod pin 7 but also the struts 8a, 8b, and 8c surrounding the rod pin 7 from super invar, it is possible to suppress linear thermal expansion of the entire main body in the axis O direction.

As explained above, according to the pressure sensor 1 according to the present embodiment, the rod pin 7 is made of a material with an extremely low coefficient of thermal expansion and has a floating structure, thereby reducing stress due to thermal expansion of the housing 2. Since the pressure is not transmitted by the rod pin 7, it is possible to accurately measure the pressure of a pressure medium at a higher temperature, in particular, the pressure of a pressure medium that reaches a high temperature of 250° C. required in semiconductor manufacturing equipment.

Although the embodiments of the pressure sensor of the present invention have been described above, the present invention is not limited to the described embodiments, and various modifications that can be imagined by those skilled in the art within the scope of the invention described in the claims. It is possible to do this.

DESCRIPTION OF SYMBOLS 1... Pressure sensor, 2... Housing, 3... First base, 4... Second base, 3a, 3b, 4a, 4b... Bottom surface, 4d... Non-through hole, 5... Pressure receiving part, 6... Sensor part, 5a , 6a...Diaphragm, 6b...Signal processing unit, 6c...Case member, 6d...Signal line, 6e...Pressure ring, 7...Rod pin, 7a, 7b...End face, 7c...Adjuster part, 8a, 8b, 8c... Support column, 9 ... Support plate, 3c, 4c, 9a... Through hole, 10... First sliding member, 11... Second sliding member, O... Axis, P... Pressure.

Claims (9)

A pressure sensor used in semiconductor manufacturing equipment,
A hollow cylindrical housing,
a first base provided on one end side of the housing;
a second base provided on the other end side of the housing;
a diaphragm supported by the first base and elastically deformed when subjected to pressure;
a pressure detection element supported by the second base and configured to detect stress caused by elastic deformation of the diaphragm and convert it into an electrical signal;
a pressure transmission member that penetrates the first base and the second base and is provided between the diaphragm and the pressure detection element;
a first sliding member provided between the outer surface of the second base and the inner peripheral surface of the housing;
The pressure sensor is characterized in that the pressure transmitting member is formed of a metal material having a linear thermal expansion coefficient of 1.3×10-6/°C or less in the range from 30°C to 100°C. The pressure sensor according to claim 1,
A through hole is formed in each of the first base and the second base along the central axis in the longitudinal direction of the housing,
The pressure sensor is characterized in that the pressure transmission member is inserted into the through hole and provided along the central axis. The pressure sensor according to claim 2,
Furthermore, a plurality of supports are provided between the first base and the second base,
The plurality of support columns are provided in parallel to the central axis at positions spaced apart from the central axis so as to surround the pressure transmitting member. The pressure sensor. The pressure sensor according to any one of claims 1 to 3,
one end of the pressure transmission member is welded to the diaphragm;
The other end of the pressure transmitting member is welded to the detection surface of the pressure detection element. A pressure sensor. The pressure sensor according to any one of claims 1 to 3,
The pressure sensor is characterized in that the pressure transmission member is made of a super invar material. The pressure sensor according to any one of claims 1 to 3,
The pressure sensor is characterized in that the first sliding member is formed of a material containing a fluororesin, which has a relatively low thermal conductivity among resin materials. The pressure sensor according to any one of claims 1 to 3,
The pressure sensor is characterized in that the pressure transmitting member is configured to be splittable in the longitudinal direction, and the divided portion is configured so that the length of the pressure transmitting member in the longitudinal direction can be adjusted. The pressure sensor according to claim 3,
A pressure sensor characterized in that the plurality of support columns are formed of a super invar material. The pressure sensor according to claim 3,
Further, a support plate provided between the first base and the second base and supporting the plurality of pillars and the pressure transmission member;
a second sliding member disposed between the support plate and the inner peripheral surface of the housing;
The pressure sensor is characterized in that the second sliding member is formed of a material containing fluororesin, which has a relatively low thermal conductivity among resin materials.