JP2004311631A - Steam annealing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem of conventional high pressure annealing procedure in which a processed work is often spoiled with spotlike stains. <P>SOLUTION: When the temperature (T) in a processing chamber 19 becomes higher by Δt than the saturation temperature (t) for the inner pressure of the processing chamber 19 after preheating (H1), heating means 25c and 25d are actuated to evaporate pure water by heating a pure water holding chamber 20 thus raising the saturation temperature (t) for the inner pressure of the processing chamber 19 and the saturation steam pressure (P) in the annealing chamber 19. After the saturation steam pressure (P), the saturation temperature (t) and the temperature (T) in the processing chamber 19 are settled at specified levels (H2), annealing work is started while sustaining the saturation temperature (t) and the saturation steam pressure (P) at constant levels. After ending the annealing work (H3), the T, t and P are returned gradually back to initial levels while sustaining the temperature (T) at a level higher by Δt than the saturation temperature (t). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention generally relates to a high-pressure annealing method for a liquid crystal glass substrate, a silicon wafer, and the like, and more particularly, to a high-pressure annealing steam treatment method for preventing generation of a stain on an oxide film formed on a liquid crystal glass substrate, a silicon wafer, and the like. About.
[0002]
[Prior art]
When annealing a glass substrate for liquid crystal or a silicon wafer, the surface of the glass substrate for liquid crystal or a silicon wafer is heated to a high temperature of 600 ° C. or more to oxidize the surface and form an oxide film thereon. Is widely known. However, this method cannot withstand such high heat with soda glass having a softening point of about 500 to 600 ° C., and the glass surface melts. Therefore, use of quartz glass having a softening point of about 1400 to 1700 ° C. instead of soda glass has been required. However, quartz glass is generally expensive and uneconomical.
[0003]
The method devised there is a laser annealing method that can instantaneously oxidize only the glass surface. According to this method, even when soda glass is used, the surface does not melt, and it is not necessary to use expensive quartz glass. However, with this laser annealing method, it is difficult to form a highly accurate oxide film, and it is not possible to expect formation of a highly accurate glass oxide film.
[0004]
Therefore, today, a high-pressure annealing steam treatment method of forming an oxide film by a high-pressure annealing apparatus as shown in FIG. 6 is widely used. This high-pressure annealing apparatus disposes the high-temperature steam heated by the heating means 2 and 3 in the lower internal container 1 to the liquid crystal glass substrate or the work 6 placed in the glass substrate cassette 5 via the flow path 4. The high-pressure annealing steam treatment is performed by supplying into the reaction vessel 7 in a high-pressure state. At this time, in order to prevent the reaction vessel 7 from being destroyed by the high-pressure high-temperature gas from inside the vessel, the entire reaction vessel 7 is accommodated in a large pressure vessel 8 and the pressure vessel 8 and the reaction vessel 7 are connected to each other. The internal and external pressures of the reaction vessel 7 are balanced by pressurizing the space defined therebetween. Further, a first additional heater 9a is provided between the pressure vessel 8 and the reaction vessel 7 around the reaction vessel 7 to further accelerate the processing reaction and to form a high-quality oxide film. A second additional heater 9b is provided in the upper part of the above to further heat the steam in the reaction vessel 7 to promote the reaction (for example, see Patent Document 1).
[0005]
[Patent Document 1]
Japanese Patent Application No. 2002-285383 (FIG. 4)
[0006]
[Problems to be solved by the invention]
At present, in the annealing process, a high-pressure annealing steam treatment method is widely used. In today's high-pressure annealing steam treatment, pure water is used as a liquid for generating steam. This is because, when an oxide film is formed on a work such as a crystal glass substrate or a silicon wafer, if metal ions adhere to the oxide film, the insulating property of the oxide film is impaired and the quality of the oxide film is deteriorated. . Therefore, in order to maintain the quality of the product, it is necessary to minimize the entry of metal ions, dust in the air, and the like into pure water to be used. Until now, the amount of pure water required for one annealing operation has been specified in advance, only that amount is injected into the pure water container, and the pure water container is set at a predetermined position in the pressure vessel. Annealing work. Then, in the next operation, pure water is replenished by the same procedure again. Due to such an operation procedure, an extremely high degree of cleanliness is required for the operation of supplying pure water. However, impurities are often mixed into pure water, and as a result, predetermined quality cannot be obtained.
[0007]
For this reason, as shown in FIG. 6, a method has been developed in which an amount of pure water required for one annealing operation is supplied from outside to a pure water container in the pressure vessel 8. As a result, the chance of impurities being mixed into pure water is reduced. However, in this method, since the amount of pure water necessary for one annealing operation is supplied every time the annealing operation is started, if the pure water container is damaged, leakage from the reaction container, etc. occurs. Insufficient pure water. Therefore, the operation must be stopped once and pure water must be sent again only for the shortage.
[0008]
However, in practice, the reaction vessel is made of a sturdy steel material, and furthermore, the inside of the pure water vessel cannot be seen because the heating means and various pipes are clogged. As a result, it cannot be determined whether or not pure water is insufficient. For this reason, there has been a problem that an empty firing state often occurs and an accident occurs in which the reaction vessel is damaged. Usually, the reaction vessel is made of expensive quartz glass, the damage of which costs tens of millions of yen at today's price. In addition, in today's annealing apparatus, there is no means for knowing the amount of pure water shortage due to water leakage or the like. Therefore, there is a problem that the amount of pure water to be supplied again cannot be known. Furthermore, since the annealing operation is performed at an extremely high pressure (usually several tens of atmospheres), there is no valve device that can supply pure water into a pressure vessel under such a high pressure today.
[0009]
Further, according to the conventional high-pressure annealing treatment procedure, there is a problem that a spot-like stain often occurs on the workpiece after the treatment. As a result of various studies by the inventor on the cause, in the past, in the high-pressure annealing treatment, after all the setting operations were completed, the heating unit first performed the heating operation prior to the heating operation inside the pure water holding chamber by the heating unit. Although pre-heating work is performed inside the annealing chamber, no special attention was paid to the heating conditions of the annealing chamber and the heating conditions of the pure water holding chamber during the actual annealing process. I discovered that there was a cause. Therefore, the present invention solves this problem by always setting the heating means for the annealing chamber and the heating means for the pure water holding chamber in a specific control relationship.
[0010]
[Means for Solving the Problems]
In the annealing steam treatment method according to the first invention, the saturation steam pressure (P) in the annealing treatment vessel disposed in the pressure chamber, the saturation temperature (t) with respect to the internal pressure of the treatment vessel, and the temperature in the treatment vessel (T), in an annealing steam treatment method for forming an oxide film on a work using pure water under high temperature and high pressure, is disposed in a pressure chamber in order to raise the temperature in the processing vessel. The heating devices 25a and 25b are activated to pre-heat the workpiece, and after the temperature in the processing container reaches a temperature Δt higher than the saturation temperature (t) with respect to the internal pressure of the processing container. In (H1), the heating means 25c and 25d are activated to increase the saturation temperature (t) with respect to the internal pressure of the processing vessel and the saturated vapor pressure (P) in the annealing processing vessel, while increasing the temperature. A preparatory heating step of gradually preheating the heat, a saturated vapor pressure (P) in the annealing container, a saturation temperature (t) with respect to the internal pressure of the processing container, and a temperature (T) in the processing container. After a predetermined value (H2) is reached, the annealing temperature (t) with respect to the internal pressure of the processing vessel and the saturated vapor pressure (P) in the annealing processing vessel are maintained at constant values, respectively, while the annealing process is performed. When the annealing process and the annealing process are completed (H3), the saturated vapor pressure (P) in the annealing container and the saturation temperature (t) with respect to the internal pressure of the processing container are initialized. (H4) return step, which gradually returns to the value (0 position), through the preparatory heating step, the annealing processing step, and the return step, the temperature (T) in the processing vessel is set to the internal pressure of the processing vessel. To The temperature is always maintained at Δt higher than the saturation temperature (t). This can prevent spots on the workpiece after the annealing.
[0011]
In the annealing steam treatment method according to the second invention, Δt is at least 10 ° C. or more and 500 ° C. or less. This enables optimal spot prevention processing.
[0012]
In the annealing steam treatment method according to the third aspect of the present invention, the pressure inside the processing vessel (T) and the saturation temperature (t) with respect to the internal pressure of the processing vessel are measured by a pressure gauge. Specified by measuring with. This enables more accurate temperature control and achieves high-quality annealing.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 shows an automatic pure water supply system 10 for performing an annealing steam treatment method according to the present invention. The system 10 generally includes a high-pressure annealing apparatus 11 for performing an annealing action by using pure water, and a pure water outside the apparatus for supplying the high-pressure annealing apparatus 11 with pure water. And a valve unit 13 for supplying pure water from the tank 12 to the annealing device 11.
[0014]
The high pressure anneal apparatus 11 has a rigid pressure vessel or outer can 15, generally made of steel. The pressure vessel 15 is composed of an upper half 16 and a lower half 17, and the two halves 16, 17 are tightly sealed via sealing means. Further, a water cooling chamber (not shown) for accommodating water for cooling water for cooling the outer wall of the pressure vessel 15 is arranged so as to surround the pressure vessel 15. Inside the sealed pressure vessel 15, a reaction vessel or inner can 18 made of, for example, quartz glass, Pyrex (R), or another glass member is accommodated and fixed at a predetermined position. The reaction vessel 18 includes an upper annealing treatment chamber 19 and a lower pure water holding chamber, that is, an internal fluid source 20. Inside the annealing chamber 19, a thin plate or work 21 to be subjected to high-pressure annealing, such as a liquid crystal glass substrate or a silicon wafer, and a cassette 22 for holding these works 21 at predetermined intervals are accommodated. The lower part of the annealing chamber 19 is closed by an end cap 23, and a passage 24 communicates the annealing chamber 19 with the pure water holding chamber 20. Further, the end cap 23 seals and separates the inside of the pressure vessel 15 and the inside of the reaction vessel 18 via a known sealing means.
[0015]
Heating means 25a and 25b are arranged on the side and above the reaction vessel 18 in the pressure vessel 15. Further, similar heating means 25 c and 25 d are arranged in the pressure vessel 15 below the end cap 23, around the passage 24 and below the pure water holding chamber 20. Further, the pressure vessel 15 is provided with a means 26a for adjusting the internal pressure and a means (not shown) for measuring the temperature. Similarly, the reaction vessel 18 is provided with a means 26b for adjusting the pressure therein and a means (not shown) for measuring the temperature. Here, the internal pressure of the pressure vessel 15 and the internal pressure of the reaction vessel 18 are always adjusted to be substantially the same pressure, whereby only the internal pressure of the reaction vessel 18 increases during operation, Although it is possible to prevent an accident such that the pressure vessel 15 is damaged, preferably, the internal pressure of the reaction vessel 18 is slightly higher than the internal pressure of the pressure vessel 15. This is to prevent the gas in the pressure vessel 15 from flowing into the reaction vessel 18 and contaminating the work in the reaction vessel.
[0016]
Further, a drain reservoir 27 is preferably formed in the lowermost half of the lower half 17 constituting the pressure vessel 15. Due to some reason (for example, damage to the annealing chamber 19 or the pure water holding chamber 20 or damage to the sealing means), the drain reservoir 27 is filled with the pressure vessel 15 from the upper part of the annealing holding chamber 19 or the pure water holding chamber 20. The water vapor leaked into the upper half 16 or the lower half 17 whose surroundings are cooled by cold water is condensed in the pressure vessel 15 or pure water leaked from the pure water holding chamber 20 is accumulated. The drain sump 27 has a sensor means 28 for detecting the amount of drain accumulated in the sump 27, the inflow speed of the drain, and the like, and a drain discharge valve 29 for discharging the drain accumulated there to the outside of the pressure vessel 15. Are provided.
[0017]
Pure water is supplied to the pure water holding chamber 20 in the reaction vessel 18 from the external pure water storage tank 12 via the pure water channel 30a, the valve device 13, and the pure water guide channel 30b. Further, the pure water holding chamber 20 is provided with a discharge means 31 for discharging the pure water held therein to the outside of the pressure vessel 15.
[0018]
The pure water storage tank 12 includes a sealed tank main body 33, a supply line 34 for supplying pure water into the tank main body 33, and an opening / closing valve 35 for adjusting the pressure in the tank main body 33. A high-pressure inert gas (for example, nitrogen gas) is forcibly supplied into the ventilation line 36 and the tank main body 33 to bring the inside of the tank main body 33 into a high-pressure state. And a supply line 37 for forcibly feeding into the inside 30a. The supply line 34 and the pure water flow path 30a are provided with on-off valves 43a and 43b, respectively. The tank body 33 is provided with an upper limit alarm sensor 38, an upper limit detection sensor 39, a leak detection sensor 40 due to backflow, a lower limit detection sensor 41, and a lower limit alarm sensor 42 for detecting the level of pure water.
[0019]
Next, an example of the structure of the valve device 13 will be described with reference to FIG. Although the valve device 13 can be effectively used for transporting a fluid other than pure water, the fluid to be transported is described here as pure water for ease of explanation. The valve device 13 can be mounted at an appropriate position on the upper half 16 or the lower half 17 constituting the pressure vessel 15. In the illustrated example, the valve device 13 is mounted so as to pass through a central through hole 45 provided in a flange-shaped metal fitting 44 integrated with the lower half body 17. However, the present invention is not limited to this. It is also possible to fix a flange-shaped fitting 44 to an opening formed in the lower half 17 by welding or the like, and attach the valve device 13 to the fitting 44.
[0020]
The valve device 13 includes a valve body 46 extending in the longitudinal direction, a receiving member that receives pure water from outside into the valve device 13, that is, an external fluid connection member 47, and a delivery member that sends out the received pure water from the valve device 13. That is, the internal fluid connecting member 48, the valve body 49 that can move the inside of the valve body 46 in the longitudinal direction, and the engagement that engages with a holding member that tightens and holds the valve body 46 to the flange 44, that is, a screw 59 described later. A member 50, a starting member 51 for starting the valve element 49 in the vertical direction, a connecting member 52 for connecting the starting member 51 and the valve element 49, and a lower end of the valve body 46, It is constituted by a lower end portion, a cover member 53 surrounding the activation member 51 and the connection member 52.
[0021]
The valve body 46 extending in the longitudinal direction extends along the longitudinal axis and communicates in the vertical direction, and has an elongated hole 55 through which the valve element 49 slides. The hole 55 includes an enlarged diameter hole 55a in the upper portion, a reduced diameter hole 55b in the lower portion communicating therewith and having a diameter slightly smaller than the enlarged diameter hole, and an upper portion and a lower portion. And a conical valve seat 55c formed to incline downward at a connection portion with the valve seat 55c. Further, an inner thread is formed at the upper end of the hole 55a. On the other hand, a lateral hole 57 is formed in the middle of the hole 55b so as to extend laterally therefrom, and the lateral hole 57 is also formed with an internal thread. An enlarged flange 58 is formed in an upper portion of the valve body 46. The diameter of the diameter-enlarged flange 58 is larger than the diameter of the central through hole 45 provided in the metal fitting 44, and the valve body 46 can escape above the metal fitting 44, but cannot escape below. It has become. Further, an outer screw 59 is formed on the outer surface of the valve body 46 at a substantially central position.
[0022]
The receiving member 47 that receives pure water from the outside into the valve device 13 is formed of a hollow member. One end of the receiving member 47 is tapered so that a conduit or the like constituting the pure water flow path 30a can be easily received. An external screw is formed at the other end of the receiving member 47, and the external screw is screwed into an internal screw of the lateral hole 57 of the valve body 46. As a result, pure water introduced into the hollow hole of the receiving member 47 is conducted through the lateral hole 57 into the hole 55b in the longitudinal direction of the valve body 46.
[0023]
The delivery member 48 that sends out the received pure water from the valve device 13 is also formed of a hollow member. One end of the delivery member 48 is tapered so that it can easily receive a pure water guide flow path 30b formed of a conduit for introducing pure water into the pure water holding chamber 20 in the pressure vessel 15. An external thread is formed at the other end of the delivery member 48, and the external thread is screwed into an internal thread formed at the upper end of a hole 55 a extending in the longitudinal direction of the valve body 46. . As a result, pure water introduced into the hollow hole of the receiving member 47 passes through the horizontal hole 57, then passes through the longitudinal holes 55b and 55a of the valve body 46, passes through the hollow hole of the sending member 48, and passes through the guide passage 30b. The water is sent out to the pure water holding chamber 20 through the storage unit.
[0024]
The valve element 49 movable in the longitudinal direction through an elongated hole 55 formed to extend in the longitudinal direction inside the valve body 46, is located in the upper enlarged hole 55a of the elongated hole 55, and has a generally comb shape. An upper end portion 60, an intermediate shaft portion 61 having a diameter smaller than the diameter of the lower diameter reducing hole 55b of the elongated hole 55, and a lower shaft having a diameter substantially similar to the diameter of the lower diameter reducing hole 55b of the elongated hole 55. And a portion 62, which are preferably integrally formed. The upper end portion 60 of the valve body 49 having a top shape contacts the valve seat 55c to prevent pure water from flowing from the sending member 48 side to the receiving member 47 side, but from the receiving member 47 side to the sending member 48 side. Allowed to flow to. Therefore, a sealing means 63 such as an O-ring is attached to the lower inclined surface of the upper end portion 60 having the top shape, and the O-ring 63 comes into close contact with the valve seat 55c. However, if necessary, a sealing means such as an O-ring may be provided on the valve seat 55c. Since the intermediate shaft portion 61 has a diameter smaller than the diameter of the reduced diameter hole 55b below the elongated hole 55, pure water pressed into the hole 55 is defined between the hole 55b and the intermediate shaft portion 61. Can be easily moved upward through the space. This is because the lower shaft portion 62 has substantially the same diameter as the diameter of the reduced diameter hole 55b of the elongated hole 55, and prevents the pure water from flowing out below the hole 55. In addition, the lower shaft portion 62 is provided with an O-ring 64 (two in the illustrated example, but the present invention is not limited to this, and one or three or more may be provided). It is completely prevented.
[0025]
The holding member 50 that tightens and holds the valve body 46 to the flange fitting 44 is a tightening member that is screwed into an external screw 59 formed at an intermediate portion of the valve body 46. By tightening the tightening member 50, the O-ring 65 mounted on the enlarged diameter flange 58 of the valve body 46 is strongly pressed against the upper surface of the fitting 44. As a result, the pressure in the pressure vessel 15 is maintained, and the mounting of the valve body 46 is achieved accurately and quickly.
[0026]
The activation member 51 that activates the valve element 49 in the up and down direction in the hole 55 includes, for example, an air cylinder, a solenoid valve, a hydraulic device, and the like. The activation member 51 operates in conjunction with an opening valve in the high-pressure inert gas supply line 37 that sends out pure water from the tank body 33 to the pure water holding chamber 20. The starting member 51 is connected to the lower end of the valve body 49 via the connecting member 52. Therefore, when the high-pressure inert gas is supplied to the tank body 33, the activation member 51 is activated to move the valve body 49 upward to open the valve seat 55a, thereby opening the inside of the lateral hole 57 of the valve device 13. The pure water introduced into the pure water holding chamber 20 via the feeding member 48 via the elongated hole 55 and the pure water guide channel 30b. During operation, the reaction vessel 18 and the pure water holding chamber 20 are normally in a high pressure state. Therefore, when pure water is supplied during operation, the activation member 51 moves the valve body 49 upward against the high pressure. Although it is necessary to push up, when the introduction of the pure water is stopped, when the operation of the starting member 51 is stopped, the introduction is performed because the valve body 49 comes into close contact with the valve seat 56 by the high pressure in the pure water holding chamber 20. Will be blocked. Of course, the actuating member 51 may be actuated to pull the valve element 49 downward to forcibly bring the valve element 49 and the valve seat 56 into close contact with each other.
[0027]
The connecting member 52 that connects the actuating member 51 and the valve element 49 includes, for example, a screw hole into which a lower end of the valve element 49 is screwed and a screw hole into which an actuating element of the actuating member 51 is screwed. It is a screw member known per se that has an end portion and can adjust the positional relationship between the two. However, a connecting piece other than the screw member may be used as long as it connects the two, and in some cases, the connecting piece may be omitted. In the illustrated example, both are fixed with set screws to prevent loosening.
[0028]
A cover member 53 attached to the lower end portion of the valve body 46 and surrounding the lower end portion of the valve element 49, the activation member 51, and the connection member 52 is a cover for protecting the activation member 51 and the connection member 52. It is. Note that a terminal of the activation member 51 for appropriately receiving information from the pure water storage tank side is provided outside the cover member 53 so that the activation member 51 is appropriately activated.
[0029]
When the fluid to be supplied is pure water, at least these members 46, 47, 48, and 49 are called, for example, polyacetal and Teflon (R) in order to prevent metal ions from being mixed into the pure water. It is desirable to mold it from such polytetrafluoroethylene, polycarbonate, and other engineering plastic materials. However, when the fluid to be supplied is one that allows mixing of metal ions or the like, it can be formed of a metal member. Further, the pure water storage tank 12, the valve device 13, the flow paths 30a and 30b, and the pure water holding chamber 20 form a closed passage so that foreign matter does not enter.
[0030]
FIG. 3 is a valve device similar to FIG. 2 showing another specific example. The embodiment shown in FIG. 3 differs from the embodiment shown in FIG. 2 in the means for mounting the valve body to the pressure vessel 15 shown in FIG. 1, and the other points are substantially the same. In FIG. 2, the length dimension of the flange-shaped mounting bracket 44 is specified in advance, and the valve device is configured according to the dimension, so that the entire length of the valve device is somewhat longer. However, in the embodiment of FIG. 3, it is possible to previously form a mounting hole in the pressure vessel 15 where the valve device is to be mounted, and to mount the valve device there. For this reason, the dimensions of the mounting bracket can be freely set, and according to this specific example, there is an advantage that the dimensions of the entire valve device can be reduced to about half the length of the entire valve device shown in FIG. That is, the valve device shown in FIG. 3 can be freely installed at the lower half 17 constituting the pressure vessel 15 or at another appropriate position. Hereinafter, only the differences between the valve device 70 shown in FIG. 3 and the valve device 13 shown in FIG. 2 will be described.
[0031]
In FIG. 3, it is assumed that the valve device 70 is mounted on the lower half 17 constituting the pressure vessel 15. First, a mounting hole 69 having a predetermined size is formed at a specific position of the lower half 17 constituting the pressure vessel 15 for mounting the valve device 70. The valve device 70 includes a valve body 71 extending in the longitudinal direction, a receiving member for receiving pure water from outside into the valve device 70, that is, an external fluid connection member 72, and a delivery for sending the received pure water from the valve device 70. The valve device 70 is fastened to the member, that is, the internal fluid connecting member 73, the valve body 74 that can move in the longitudinal direction inside the valve body 71, and the lower half 17 (see FIG. 1) constituting the pressure vessel 15. A fastening member that engages with a screw 81 to be described later, an activation member 76 that activates the valve element 74 in the vertical direction, a connection member 77 that connects the activation member 76 and the valve element 74, A lower end of the valve body 74 is attached to a lower end of the main body 71, and includes a cover member 78 surrounding the activation member 76 and the connecting member 77.
[0032]
The valve body 71 extending in the longitudinal direction has an elongated hole 79 extending inside along the longitudinal axis and communicating with the up and down direction, and the valve body 74 slides on the inner surface. Further, an enlarged diameter flange 80 is formed in an upper portion of the valve main body 71. Further, an external thread 81 is formed on the outer surface of the valve main body 71 from a substantially central position of the valve main body to a portion below the enlarged diameter flange 80.
[0033]
The fastening member 75 for receiving the valve body 71 has a central through-hole 82 penetrating in the longitudinal direction, and the through-hole 82 has an internal screw 83. The outer diameter of the enlarged flange 80 of the valve body 71 is larger than the diameter of the central through hole 82 provided in the fastening member 75, and the valve body 71 can escape above the fastening member 75, Is unable to escape. Further, an outer screw 81 of the valve body 71 is screwed to an inner screw 83 of the fastening member 75. Accordingly, by tightening the fastening member 75, the O-ring 84 mounted on the enlarged diameter flange 80 of the valve body 71 is strongly pressed against the upper surface of the fastening member 75. Thereby, sealing between the valve body 71 and the fastening member 75 is achieved. In this manner, a valve device unit 85 in which the fastening member 75 is incorporated in the valve device 70 in a sealed state is formed.
[0034]
After that, the valve device unit 85 is disposed in the mounting hole 69 formed at a predetermined position of the pressure vessel 15 where the valve device 70 is to be mounted, and the unit 85 is sealed to the mounting hole 69 by welding 86. Attach and fix in the state. In order to easily and reliably perform the welding operation, the mounting hole 69 formed in the pressure vessel 15 has a shape similar to the outer shape of the fastening member 75, and the size of the mounting hole 69 is smaller than the outer diameter of the fastening member 75. It is desirable to form them with dimensions that are approximately equal or somewhat larger. Further, as shown in FIG. 3, the fastening member 75 has a reduced size portion 87 that penetrates the mounting hole 69 to the outside of the pressure vessel 15, and an enlarged size portion 88 that is somewhat larger and does not penetrate the mounting hole 69. And a stepped shape. Thereby, the positioning of the valve device unit 85, particularly the fastening member 75, with respect to the mounting hole 69 of the pressure vessel 15 becomes easy, and the subsequent welding operation can be performed easily, reliably and quickly. Further, a set screw (not shown) that reaches the inner screw 83 of the central through hole 82 from the outer portion thereof and then presses the outer screw 81 of the valve body 71 is engaged with the fastening member 75, and the fastening member 75 is loosened. Can be prevented.
[0035]
The structure, operation, and function of each member 72, 73, 74, 76, 77, 78 other than the valve body 71 constituting the valve device 70 are the same as those of the embodiment shown in FIG. The method of supplying pure water from the pure water storage tank, the method of stopping the same, and the like are the same as those in the previous embodiment, and thus will not be described in detail. Further, when the fluid to be supplied is pure water, these members 71, 72, 73, 74, 75, etc. are made of, for example, polyacetal, Teflon (R) to prevent metal ions from being mixed into the pure water. It is desirable to mold it from polytetrafluoroethylene, polycarbonate, or other engineering plastic materials such as those referred to as. However, when the fluid to be supplied is one that allows mixing of metal ions or the like, it can be formed of a metal member.
[0036]
Here, the metal fitting 44 or the fastening member 75 is arranged so as to surround the enlarged diameter portion of each of the valve bodies 46 and 71, and in addition to the function of mounting the valve devices 13 and 70 to the pressure vessel 15, The main bodies 46 and 71 also have a function of preventing the enlarged diameter portion from expanding even if a large pressure is applied to the enlarged diameter portion of the valve body by the high pressure in the reaction vessel 18 and preventing the main body 46, 71 from being broken. Have. Therefore, the metal fitting 44 and the fastening member 75 are desirably made of metal.
[0037]
When performing an annealing process in the automatic pure water supply system 10, a workpiece or a work 21 is set in a cassette 22 in the reaction chamber 18 and then pure water is supplied from the pure water storage tank 12 into the pure water holding chamber 20. I do. When supplying pure water from the pure water storage tank 12 into the pure water holding chamber 20, first, pure water is charged into the tank body 33 of the pure water storage tank 12, and then pure water is stored from the tank body 33. Pure water is supplied to the chamber 20.
[0038]
First, a method for putting pure water into the tank body 33 of the pure water storage tank 12 will be described. When pure water is charged into the tank body 33, the valve device 13 and the opening / closing valve 43b provided in the pure water flow path 30a are first closed. Here, the valve device 13 is a valve for introducing pure water into the pure water holding chamber 20, and the opening / closing valve 43 b is a valve for extracting pure water from the tank body 33. Next, the on-off valve 35 of the ventilation line 36 is opened to communicate the inside of the tank body 33 to the atmosphere. In this state, the open / close valve 43a of the pure water supply line 34 is opened, and pure water is supplied from a pure water supply source (not shown) into the tank body 33. In the tank body 33, an upper limit alarm sensor 38, an upper limit detection sensor 39, a leak detection sensor 40 due to backflow, a lower limit detection sensor 41, and a lower limit alarm sensor 42 are provided for detecting the level of pure water. These sensors are preferably plastic float switches in order to prevent foreign substances, particularly metal ions, from entering the pure water. Thus, the pure water supplied from the pure water supply line 34 accumulates in the tank body 33. When the pure water accumulates to an appropriate position, the upper limit detection sensor 39 operates. At this time, the on-off valve 43a is closed to stop the supply of pure water. However, if pure water is further carelessly supplied into the tank main body 33, the upper limit alarm sensor 38 is activated, and it is dangerous if the amount of pure water stored in the tank main body 33 becomes higher than this. Let me know. In this case, the on-off valve 43a is closed, and the on-off valve 43b is opened to extract excess pure water from the tank body 33. When the amount of pure water in the tank body reaches an appropriate amount, the on-off valve 35 of the ventilation line 36 is closed. Thereby, an appropriate amount of pure water is held in the tank body 33.
[0039]
Next, a procedure for supplying pure water from the tank body 33 to the pure water holding chamber 20 will be described. At this time, first, the pressure adjusting means 26b and the pure water discharging means 31 are opened to communicate the reaction vessel 18 with the atmosphere, and the pure water remaining in the pure water holding chamber 20 is discarded. Next, the valve means 13 is opened while only the pure water discharge means 31 is closed, and a high-pressure inert gas such as nitrogen gas is supplied from the high-pressure inert gas supply source into the tank body 33 via the supply line 37. I do. As a result, the pure water in the tank main body 33 is pressure-conveyed by the inert gas via the pure water flow path 30a, the valve main body 13, and the pure water guide flow path 30b. This prevents metal ions and other foreign matter from entering the pure water provided into the pure water holding chamber 20. The supply of the pure water by the high-pressure gas continues until the level of the pure water in the tank body 33 reaches the position where the lower limit detection sensor 41 operates. This is because the lower limit detection sensor 41 notifies the lower limit of the appropriate amount of pure water contained in the tank body 33. If the pure water is inadvertently supplied to the pure holding chamber 20 by the high-pressure gas and the level in the tank body 33 drops to the position of the lower limit alarm sensor 42, the lower limit alarm sensor 42 is activated and the tank is put into the tank body 33. If the amount of pure water contained falls below this level, it is dangerous.
[0040]
It can be understood that the amount of pure water between the lower limit detection sensor 41 and the upper limit detection sensor 39 in the tank body 33 is the optimal amount of pure water accommodated in the pure water holding chamber 20, that is, one annealing. It would be the amount of pure water used in the operation. After supplying an appropriate amount of pure water to the pure water holding chamber 20, the supply of high-pressure inert gas is stopped and the valve device 13 is closed, and the annealing operation at high temperature and high pressure is started in such a state. If pure water flows back from the pure water holding chamber 20 into the tank body 33 via the valve device 13 for some reason (for example, damage to the valve device 13) during the annealing operation, The level of pure water in the main body 33 rises from the position of the switch 41. When the level reaches the position of the leak detection sensor 40, the sensor 40 is activated. In this way, the backflow leak detection sensor 40 notifies that the pure water has flown back from the pure water holding chamber 20. At this time, it is necessary to stop the operation of the system 10 and check it immediately in order to correct the reason. Until now, such backflowed pure water could not be recognized from the outside because of a closed passage, and furthermore, such backflow detection means did not exist, so that often empty heating occurred and the reaction chamber 18 This fear can be completely eliminated in this device, which may cause breakage or other damage.
[0041]
In addition, the system 10 has a drain reservoir 27 near the lower bottom of the lower half 17 that constitutes the pressure vessel or outer can 15. As described above, in the drain reservoir 27, drain that leaks and condenses from the reaction container 18 into the pressure container 15 is stored. Therefore, when starting up the system 10, it is desirable to first open the drain discharge valve 29 and completely discard the drain in the drain reservoir 27. Pure water is a non-conductive substance, but the liquid that has condensed on the wall surface of the pressure vessel 15 and has flowed into the drain reservoir 27 or the liquid that has flowed into the drain reservoir 27 from the pure water holding chamber via the lower half 17 is By collecting the dust, it becomes a conductive liquid. The sensor means 28 measures the total amount of the liquid flowing into the drain reservoir 27 or the fluctuation of the flow rate of the drain flowing into the drain reservoir 27. The drain reservoir 27 is large enough to accommodate the amount of pure water required for one annealing operation in consideration of leakage of all pure water in the pure water holding chamber 20. Is preferred.
[0042]
The switch means 28 disposed in the drain reservoir 27 is composed of a plurality of float switches 28a, 28b, 28c, 28d set at different depth positions of the drain reservoir 27, for example, as shown in FIG. Here, the float switches 28a, 28b and 28c are respectively set when the liquid of 液体, １ ／ and ／ of the volume of the drain reservoir 27 has accumulated in the drain reservoir 27 and at the highest position. The switch 28d is activated when the same amount of liquid as the amount of pure water required for one annealing process is accumulated in the drain reservoir 27. Further, these switches 28a, 28b, 28c and 28d are sequence-controlled with each other, and the time difference between the activation of the switches is determined, whereby the amount of drain per time flowing into the drain reservoir 27 can be known. By operating the switch 28a, it can be seen that a leak has occurred in the pressure vessel 15. However, when the time from the start of the annealing operation to the time when the switch 28a is activated, and further the time from the time when the switch 28a is activated to the time when the switch 28b is activated, are slightly longer than the time required for the annealing process time, Can continue the annealing operation without replenishing the pure water or stopping the system 10, but if the time is short, it is necessary to consider replenishing the pure water or stopping the annealing operation. This makes it possible to prevent an accident due to the empty firing of the reaction vessel 18 in advance. Of course, more float switches can be arranged to perform more detailed leakage management.
[0043]
Since such a drain reservoir did not exist in the pressure vessel used in the conventional system, the leakage of pure water causing such a drain was not noticed, and the reactor 18 was often emptied by heating. In some cases, serious damage such as breakage of the container, re-annealing work, or generation of a large number of defective products may occur, but such a problem is completely solved by this system.
[0044]
Further, in this system, a novel high-pressure annealing operation procedure is disclosed. According to the conventional high-pressure annealing treatment procedure, an accident often occurs in which spot-like stains are generated on the workpiece after the treatment. As a result of various studies by the inventor on the cause, in the high-pressure annealing process, after completing all the setting operations, first, prior to the heating operation inside the pure water holding chamber 20 by the heating means 25c and 25d. The preheating operation of the inside of the annealing chamber 19 by the heating means 25a and 25b is performed, but during the subsequent actual annealing operation, the heating conditions of the annealing chamber 19 and the heating conditions of the pure water holding chamber 20 are considered. I found that the cause was due to not paying special attention.
[0045]
Therefore, the inventor always tries to set the heating means 25a and 25b of the annealing chamber 19 and the heating means 25c and 25d of the pure water holding chamber 20 in a specific control relationship. This will be described below with reference to FIG. In this novel high-pressure annealing method, when the saturated vapor pressure in the annealing chamber 19 is P, the saturation temperature with respect to the internal pressure of the processing chamber 19 is t, and the temperature in the processing chamber 19 is T, First, the heating devices 25a and 25b are activated to increase the temperature in the processing chamber 19. This is so-called preheating. Thereafter, after the temperature (T) in the processing chamber 19 reaches a temperature that is Δt higher than the saturation temperature (t) with respect to the internal pressure of the processing chamber 19 (H1), the heating units 25c and 25d are activated. The pure water holding chamber 20 is heated to vaporize the pure water, and the saturation temperature (t) with respect to the internal pressure of the processing chamber 19 and the saturated vapor pressure (P) in the annealing processing chamber 19 are increased. During this operation, the temperature (T) in the processing chamber 19 is always maintained at a temperature higher by Δt than the saturation temperature (t) with respect to the internal pressure of the processing chamber 19. Here, the temperature inside the processing chamber 19 is substantially the same as the temperature of the work 21.
[0046]
Next, the saturated vapor pressure (P) in the annealing chamber 19, the saturation temperature (t) with respect to the internal pressure of the processing chamber 19, and the temperature (T) in the processing chamber 19 have become predetermined values. Thereafter (H2), the annealing operation is started while maintaining the saturation temperature (t) with respect to the internal pressure of the processing chamber 19 and the saturated vapor pressure (P) in the annealing processing chamber 19 at constant values. Also at this time, the temperature (T) in the processing chamber 19 is always maintained at a temperature higher by Δt than the saturation temperature (t) with respect to the internal pressure of the processing chamber 19. When the annealing process is completed (H3), T, t, and P are maintained while maintaining the temperature (T) in the processing chamber 19 at a temperature Δt higher than the saturation temperature (t) with respect to the internal pressure of the processing chamber 19. Gradually return to the initial value. Thus, even when the saturated vapor pressure (P) in the annealing chamber 19 and the saturation temperature (t) with respect to the internal pressure in the processing chamber 19 return to the zero position (H4), respectively, The temperature (T) always maintains a temperature state that is higher by Δt than the saturation temperature (t) with respect to the internal pressure of the processing chamber 19. Therefore, the temperature (T) in the processing chamber 19 returns to the position 0 at a time (H5) later than H4. As will be apparent to those skilled in the art, the pressure fluctuation in the annealing chamber 19 causes almost the same pressure fluctuation in the pressure vessel 15, and the annealing chamber is treated so as not to be damaged. Therefore, the inert gas can be introduced into each of the insides by the pressure adjusting means 26a and 26b or the pressure adjusting means provided separately therefrom.
[0047]
By maintaining the temperature (T) in the processing chamber 19 at a predetermined temperature (for example, Δt) at all times from the beginning to the end of the annealing process, the work 21 is kept above the temperature of the pure water holding chamber. Is always kept at a high temperature. For this reason, dew condensation does not occur on the work, thereby preventing the work from being stained. Here, Δt is preferably, for example, about 10 ° C. or more and 500 ° C. or less, depending on the internal temperature of the processing chamber 19. The temperature (T) in the processing chamber 19 and the saturation temperature (t) with respect to the internal pressure of the processing chamber 19 can be measured by a thermometer. In general, measurement by a thermometer is also possible. By measuring with a pressure gauge the steam pressure that rises exponentially when the heating means is heated, without measuring with a thermometer, a higher-precision measurement effect can be obtained.
[0048]
【The invention's effect】
According to the present invention, the temperature (T) in the processing chamber 19 is always maintained at a higher temperature by a predetermined temperature (for example, Δt) from the beginning to the end of the annealing process. As a result, the work 21 is always maintained at a temperature higher than the temperature of the pure water holding chamber, so that no dew condensation occurs on the work and it is possible to prevent the work from being stained. Here, Δt is desirably, for example, 10 ° C. or more and 500 ° C. or less (10 ° C. or more and 100 ° C. or less in consideration of economy). The temperature (T) in the processing chamber 19 and the saturation temperature (t) with respect to the internal pressure of the processing chamber 19 can be measured by a thermometer. However, generally, the measurement by the thermometer may lack accuracy. Therefore, the same measurement effect can be obtained by measuring the steam pressure which rises exponentially when the heating means is heated without using a thermometer to measure these temperatures.
[Brief description of the drawings]
FIG. 1 is a schematic view of a high-pressure annealing apparatus capable of performing the method of the present invention.
FIG. 2 is a partially enlarged view of FIG. 1, and is a cross-sectional view showing a first embodiment of the automatic valve device.
FIG. 3 is a partially enlarged view of FIG. 1 and is a cross-sectional view showing a second embodiment of the automatic valve device.
FIG. 4 is an enlarged view showing a drain reservoir of FIG. 1;
FIG. 5 is an explanatory view showing a new high-pressure annealing work procedure.
FIG. 6 is a view showing a known high-pressure annealing apparatus.
[Explanation of symbols]
10: Pure water automatic supply system 11: High pressure annealing device 12: Pure water storage tank 13: Valve device 15: Pressure vessel 18: Reaction vessel 19: Annealing treatment chamber 20: Pure water holding chamber 23: End cap 24: Passage 29: Drain discharge valve 30a: pure water flow path 30b: pure water guide flow path 31: discharge means 37: high-pressure inert gas supply line 44: flange-shaped fitting 45: central through hole 46: valve body 47: receiving member 48: sending member 49 : Valve body 50: holding member 51: starting member 52: connecting member 53: cover member 55: hole 55 a: enlarged diameter hole 55 b: reduced diameter hole 55 c: valve seat 57: lateral hole 58: enlarged flange 59: outside Screw 60: Upper end part 61: Intermediate shaft part 62: Lower shaft part 69: Mounting hole 70: Valve device 71: Valve main body 72: Receiving member 73: Sending member 74: Valve body 75: Fastening member 76: Starting part 77: connecting member 78: cover member 79: hole 80: the expanded diameter member 81: external thread 82: a central through-hole 85: the valve device unit 86: Welding 87: reduced dimension of 88: enlarged dimension portion

Claims (3)

By specifying the saturated vapor pressure (P) in the annealing treatment container disposed in the pressure chamber, the saturation temperature (t) with respect to the internal pressure of the treatment container, and the temperature (T) in the treatment container, In an annealing steam treatment method for forming an oxide film on a work using pure water under high temperature and high pressure,
A pre-heating step of activating the heating devices 25a and 25b arranged in the pressure chamber to raise the temperature in the processing chamber to pre-heat the work;
After the temperature in the processing vessel reaches a temperature Δt higher than the saturation temperature (t) with respect to the internal pressure of the processing vessel (H1), the heating means 25c and 25d are activated to activate the heating means 25c and 25d. A preparation heating step of gradually preparing and heating the work while increasing the saturation temperature (t) and the saturation vapor pressure (P) in the annealing container;
After the saturated vapor pressure (P) in the annealing treatment container, the saturation temperature (t) with respect to the internal pressure of the treatment container, and the temperature (T) in the treatment container have reached predetermined values (H2). An annealing operation step of performing an annealing operation while maintaining a saturation temperature (t) with respect to the internal pressure of the processing container and a saturated vapor pressure (P) in the annealing container at constant values, respectively;
When the annealing process is completed (H3), the saturated vapor pressure (P) in the annealing container and the saturation temperature (t) with respect to the internal pressure of the processing container are gradually increased to initial values (0 position), respectively. Return (H4) return step;
Of the various stages,
Annealing steam characterized in that the temperature (T) in the processing vessel is always maintained at a temperature Δt higher than the saturation temperature (t) with respect to the internal pressure of the processing vessel throughout the preparation heating step, the annealing processing step and the return step. Processing method. 2. The annealing steam treatment method according to claim 1, wherein Δt is at least 10 ° C. or more and 500 ° C. or less. The temperature (T) in the processing vessel and the saturation temperature (t) with respect to the internal pressure of the processing vessel are specified by measuring a steam pressure which rises exponentially when the heating means is heated by a pressure gauge. Annealing steam treatment method.

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