JP2008151270A - Metal diaphragm valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a metal diaphragm valve by which a raw material gas can be stably fed with a gap held constant between the metal diaphragm valve and a valve seat in a high-temperature environment. <P>SOLUTION: The metal diaphragm 15 which performs opening and closing operations of a valve by contacting with a valve seat 14 by a pressing force of a valve bar 16 to return flexibly to an original form by releasing the pressing force of the valve bar 16 is made Hv 500 or higher in Vickers hardness by applying aging heat hardening treatment. As a result, even in a high-temperature environment, the metal diaphragm 15 can be reduced in the deterioration of a reactive force (elastic force) and in a thermal expansion amount and thereby a gap α between the metal diaphragm 15 and the valve seat 14 is held constant, so that the raw material gas is stably fed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a metal diaphragm valve, and more particularly, to a metal diaphragm valve attached to a supply pipe for a semiconductor manufacturing gas heated to a high temperature in a semiconductor manufacturing apparatus.

  2. Description of the Related Art Conventionally, as an on-off valve used in a piping system of a semiconductor manufacturing apparatus or the like, a valve that does not have a sliding portion that generates fine particles (particles) due to wear in a valve internal flow path and has no dead space is required. . A diaphragm valve is available to meet this demand.

  As shown in FIG. 7, the diaphragm valve is provided on the valve seat 4 so as to face the valve seat 4 provided at a position where the inflow passage 2 and the outflow passage 3 in the valve box 1 communicate with each other. A diaphragm 5 that is elastically deformable and has a central portion bulging upward, and a valve rod 6 that seats the diaphragm 5 on the valve seat 4 and elastically returns to its original shape and separates from the valve seat 4. It consists of

  The front end surface of the valve stem 6 has an appropriate curved shape, and the front end surface is lowered by a fluid pressure such as pneumatic pressure, a magnetic force, or manually, and thereby presses the diaphragm 5, and its central portion is downward. Is elastically deformed, and is seated on the valve seat 4 to be closed. On the other hand, when the valve stem 6 is lifted and the pressure is released, the central portion of the diaphragm 5 rises so as to elastically return to its original shape, and is separated from the valve seat 4 to open the valve.

  In recent years, with the increase in the degree of integration of semiconductor integrated circuit devices, a wide variety of source gases are used in the manufacturing process. The source gas is gasified by heating a material such as an organic metal at a high temperature, and the diaphragm valve is heated at a high temperature as well as the supply pipe so that the source gas is not re-liquefied and solidified during the supply. .

In order to cope with the high temperature of such a diaphragm valve, the diaphragm 5 and the valve seat 4 are made of metal, have excellent durability under a high temperature environment, have excellent corrosion resistance against a wide variety of source gases, and have a particle structure. A so-called all-metal metal diaphragm valve, which is rarely generated, has become the mainstream. Hereinafter, the diaphragm 5 is referred to as a metal diaphragm 5. Such a conventional technique is disclosed in Patent Document 1 shown below.
JP-A-5-296355

  In the metal diaphragm valve, after the pressure of the valve stem 6 is released, the metal diaphragm 5 is separated from the valve seat 4 by the elastic force of the metal diaphragm 5, that is, the reaction force, and the gap (gap) between the metal diaphragm 5 and the valve seat 4 is released. Source gas is supplied into the semiconductor manufacturing apparatus through α.

  In this case, since the metal diaphragm valve is heated at a high temperature, the gap α decreases as shown in FIG. 8 due to a decrease in the reaction force or thermal expansion of the metal diaphragm 5, and the raw material gas to the semiconductor manufacturing apparatus is reduced. There is a possibility that the supply amount decreases or, in the worst case, the gap α disappears and gas supply cannot be performed. Such a situation is particularly remarkable when the inside of the semiconductor manufacturing apparatus is in a vacuum as shown in FIG.

  The technical problem of the present invention has been made in view of the circumstances as described above, and its purpose is to maintain a constant gap between the metal diaphragm and the valve seat in a high temperature environment, thereby stabilizing the raw material gas. An object of the present invention is to provide a metal diaphragm valve that can be supplied.

  In order to achieve the above object, the invention according to claim 1 is directed to a valve seat provided between an inflow channel and an outflow channel in a valve box, and an elastic metal diaphragm provided on the valve seat. A metal diaphragm valve that presses the metal diaphragm against the valve seat and closes the valve, and elastically returns the metal diaphragm to its original shape when the pressing force is released, thereby opening the valve. Vickers hardness is increased to Hv500 or higher by curing heat treatment.

  The invention according to claim 2 is the invention according to claim 1, wherein the metal diaphragm is made of a cobalt alloy.

  The invention according to claim 3 is the invention according to claim 2, wherein the material composition ratio of the metal diaphragm is Co: 25 to 45%, Cr: 8 to 25%, Ni: 20 to 40%, Ti: 0 -3%, Mo: 4-15%, Nb: 0-3%, W: 0-5%.

  The invention according to claim 4 is the invention according to any one of claims 1 to 3, wherein the age hardening heat treatment is performed at 350 to 450 ° C. for 1 to 2 hours.

According to the first aspect of the invention, since the metal diaphragm is cured to a Vickers hardness of Hv500 or higher, the reaction force of the metal diaphragm can be reduced and the amount of thermal expansion can be suppressed even in a high temperature environment. Therefore, the gap between the metal diaphragm and the valve seat is kept constant, and the source gas can be stably supplied into the semiconductor manufacturing apparatus.
According to the invention which concerns on Claim 2, the metal diaphragm which consists of a cobalt alloy is excellent in abrasion resistance, heat resistance, and corrosion resistance, and does not lose the characteristic under high temperature, and hardness is maintained.

According to the invention of claim 3, the material composition ratio of the metal diaphragm is Co: 25 to 45%, Cr: 8 to 25%, Ni: 20 to 40%, Ti: 0 to 3%, Mo: 4 to Cobalt alloy with 15%, Nb: 0-3%, W: 0-5% can maximize its properties, has better heat resistance, and can lose its properties even at high temperatures. And the hardness is maintained.
According to the invention of claim 4, it is most effective to perform the age hardening heat treatment at a temperature of 350 to 450 ° C. for 1 to 2 hours.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a longitudinal sectional view showing an embodiment of a metal diaphragm valve according to the present invention, and FIG. 2 is an enlarged view of a portion A in FIG.

  1 and 2, a metal diaphragm valve 10 has a valve box 11 formed of a metal material such as stainless steel. An inflow channel 12 and an outflow channel 13 are formed in the valve box 11, and a valve seat 14 integrally formed with the valve box 11 is formed at the outlet periphery of the inflow channel 12 communicating with the inlet of the outflow channel 13. In addition to being provided, a metal diaphragm 15 is mounted on the valve seat 14 so as to face each other.

  The metal diaphragm 15 is made of a cobalt alloy that can be elastically deformed, and has a shape in which a central portion bulges upward. The material composition ratio of the cobalt alloy is Co: 25 to 45%, Cr: 8 to 25%, Ni: 20 to 40%, Ti: 0 to 3%, Mo: 4 to 15%, Nb: 0 to 3 %, W: 0 to 5%.

  The metal diaphragm 15 was subjected to age hardening heat treatment for 1 to 2 hours at a temperature of 350 to 450 ° C. after punching, and the hardness was set to Vickers hardness Hv500 or more and the tensile strength was 1777 to 2420 N / mm 2. Is.

On the metal diaphragm 15, there is provided a valve rod 16 that can be moved up and down so that the metal diaphragm 15 is seated on the valve seat 14 and is elastically restored to the original shape to be separated from the valve seat 14. The valve box 11 is provided with a coil spring 17 that urges the valve rod 16 toward the lower valve seat 14.
In a normal state in which the metal diaphragm 15 is not pressurized by the valve rod 16, the metal diaphragm valve 10 bulges upward upward, away from the valve seat 14, and the metal diaphragm valve 10 is opened.

Here, when the metal diaphragm 15 is pressed by the valve rod 16, it is pushed downward in such a manner as to follow this, and is pressed against the valve seat 14 to come into close contact. As a result, the metal diaphragm valve 10 is closed.
Further, when the pressing force of the valve stem 16 is released, the metal diaphragm 15 expands in a spherical shape upward due to its own elastic force and is restored from the valve seat 14, and the metal diaphragm valve 10 is opened. The source gas is supplied into the semiconductor manufacturing apparatus through the gap α between the metal diaphragm 15 and the valve seat 14.

  Next, an experiment was conducted to confirm the open state of the metal diaphragm valve 10 in a high temperature environment. FIG. 3 shows the valve opening state of the metal diaphragm 15 at normal temperature, and FIG. 4 shows the valve opening state of the metal diaphragm 15 at high temperature. In addition, the hardness of the metal diaphragm 15 was measured at three points with a micro Vickers tester, and the average value was obtained.

  As a result of the experiment, as shown in FIG. 4, it was found that the gap α between the metal diaphragm 15 and the valve seat 14 hardly changed compared to the normal temperature shown in FIG. 3. This is because the hardness (strength) of the metal diaphragm 15 subjected to age hardening heat treatment is increased, and the reaction force is prevented from lowering. As is apparent from FIGS. 5 and 6, the metal diaphragm 15, compared with the conventional metal diaphragm (see FIGS. 8 and 9), has a reaction force at each temperature regardless of whether the semiconductor manufacturing apparatus has an atmospheric pressure or a vacuum. It was found that the decrease was suppressed.

  Therefore, even when the temperature is high, the elastic return when the metal diaphragm 15 is opened is surely performed, so that the reduction of the gap α is avoided and the size of the gap α is made constant regardless of the temperature. Is possible.

  Such a phenomenon is considered to be caused by a decrease in the amount of thermal expansion due to an improvement in the hardness of the metal diaphragm 15. That is, the factor that fluctuates the gap α is eliminated by reducing the thermal expansion amount of the metal diaphragm 15. Further, when the hardness of the metal diaphragm 15 was lower than Hv500, the hardness was not sufficient, and a decrease in the reaction force of the metal diaphragm 15 was recognized outside the allowable range. Accordingly, it was found that the gap α was reduced and was not practical.

Thus, in the present embodiment, the metal diaphragm 15 is cured to a Vickers hardness of Hv500 or higher, so that the reaction force of the metal diaphragm 15 is reduced and the amount of thermal expansion is suppressed, and the gap α is kept constant. Therefore, even in a high temperature environment, the source gas is smoothly and stably supplied into the semiconductor device, and a situation where the supply amount is reduced or cannot be reliably supplied is avoided.
Further, since the metal diaphragm 15 is made of a cobalt alloy, it is excellent in wear resistance, heat resistance, and corrosion resistance and maintains hardness even at high temperatures.

In this case, the material composition ratio of the metal diaphragm 15 is Co: 25 to 45%, Cr: 8 to 25%, Ni: 20 to 40%, Ti: 0 to 3%, Mo: 4 to 15%, Nb: 0 Since it is set to ˜3% and W: 0 to 5%, it is more excellent in heat resistance and maintains its hardness without losing its characteristics even at high temperatures.
In addition, the age-hardening heat treatment can be effectively cured at a temperature of 350 to 450 ° C. for 1 to 2 hours, thereby effectively curing the metal diaphragm 15.

  The embodiment of the present invention has been described in detail above, but the present invention is not limited to the above-described embodiment, and the scope does not depart from the spirit of the invention described in the claims of the present invention. Thus, various changes can be made.

For example, the valve seat 14 is formed integrally with the valve box 11, but the present invention is not limited to this, and the valve seat 14 may be formed separately from the valve box 11, and a valve seat made of synthetic resin or the like is used. It doesn't matter.
Moreover, if the age hardening heat treatment of a metal diaphragm is applied to an existing metal diaphragm valve, the metal diaphragm valve of the present invention can be obtained at low cost.

It is a longitudinal cross-sectional view of the metal diaphragm valve which concerns on one embodiment of this invention. It is the A section enlarged view of FIG. It is sectional drawing explaining the valve open state at the time of normal temperature of the metal diaphragm valve shown in FIG. It is sectional drawing explaining the valve open state at the time of the high temperature of the metal diaphragm valve shown in FIG. It is a characteristic diagram of the amount of pushing and reaction force in the internal atmospheric pressure of the age-hardening heat-treated metal diaphragm. FIG. 6 is a characteristic diagram of the pressing amount and reaction force in an internal vacuum of an age hardening heat treated metal diaphragm. It is sectional drawing explaining the valve open state at the time of the high temperature of the conventional metal diaphragm valve. It is a characteristic diagram of the pushing amount and reaction force in the internal atmospheric pressure of the conventional metal diaphragm. It is a characteristic diagram of the pressing amount and reaction force in the internal vacuum of the conventional metal diaphragm.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Metal diaphragm valve 11 Valve box 12 Inflow flow path 13 Outflow flow path 14 Valve seat 15 Metal diaphragm 16 Valve rod 17 Coil spring α Gap

Claims (4)

A valve seat provided between an inflow passage and an outflow passage in the valve box; and an elastic metal diaphragm provided on the valve seat, wherein the metal diaphragm is pressed against the valve seat. In the metal diaphragm valve that closes the valve and opens the valve by elastically returning the metal diaphragm to the original shape by releasing the pressing force,
The metal diaphragm is characterized in that the Vickers hardness is Hv500 or more by age hardening heat treatment.   The metal diaphragm valve according to claim 1, wherein the metal diaphragm is made of a cobalt alloy.   The material composition ratio of the metal diaphragm is Co: 25 to 45%, Cr: 8 to 25%, Ni: 20 to 40%, Ti: 0 to 3%, Mo: 4 to 15%, Nb: 0 to 3% W: 0 to 5%, The metal diaphragm valve according to claim 2.   The metal diaphragm valve according to any one of claims 1 to 3, wherein the age hardening heat treatment is performed at 350 to 450 ° C for 1 to 2 hours.

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