JP3611495B2 - Reduced pressure moisture generator - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a moisture generation and supply apparatus mainly used in a semiconductor manufacturing apparatus. More specifically, the present invention supplies moisture gas to a downstream side in a reduced pressure state, and at the same time, increases the internal pressure in a moisture generation reactor to increase the amount of hydrogen. The present invention relates to a reduced pressure type moisture generating and supplying apparatus capable of preventing spontaneous ignition.
[0002]
[Prior art]
For example, formation of a silicon oxide film by a moisture oxidation method in semiconductor manufacturing requires ultra-high purity water exceeding at least 1000 cc / min. Therefore, the present applicant has previously developed a reactor for generating moisture having the structure shown in FIGS. 5 and 6, and Japanese Patent Application No. 8-242246 (FIG. 5) and Japanese Patent Application No. 10-345500 (FIG. 6). As this is published.
[0003]
That is, the reactor main body 21 shown in FIG. 5 is configured by combining an inlet-side furnace main body member 22 having a raw material gas supply joint 24 and a heat-resistant outlet-side furnace main body member 23 having a moisture gas extraction joint 25 in an opposing manner. Is formed. Inside the reactor main body 21, an inlet-side reflector 29a and an outlet-side reflector 29b are arranged so as to face the raw material gas supply passage 24a and the moisture gas outlet passage 25a of both the furnace main body members 22, 23, respectively. A filter 30 is provided in the inner center of the reaction furnace main body 21, and a platinum coating catalyst layer 32 is formed on the inner wall surface of the outlet-side furnace main body member 23.
[0004]
The platinum coating catalyst layer 32 is formed by fixing the platinum coating 32b on the barrier coating 32a made of nitride such as TiN formed on the inner wall surface of the furnace body member 23 by vapor deposition or ion plating. Is done.
[0005]
In the reactor main body 21 shown in FIG. 6, a relatively thick reflector 29 is provided inside the reactor main body 21, and the inner peripheral surface of the outlet-side furnace main body member 23 is provided. A platinum coating catalyst layer 32 composed of a barrier film 32a and a platinum film 32b is formed.
Note that only the barrier film 32a is provided on the outer surface of the inlet-side furnace body member 22 and the outer surface of the reflector 29, and the platinum film 32b is not formed. This is because the surface of the inlet-side furnace main body member 22 and the reflector 9 exhibits a catalytic action, thereby preventing a reaction between O ₂ and H ₂ from occurring and causing a local temperature increase.
[0006]
Referring to FIG. 5, hydrogen and oxygen, which are source gases supplied to the inside of the reactor main body 21 through the source gas supply passage 24a, are for diffusion composed of an inlet side reflector 29a, a filter 30 and an outlet side reflector 29b. The member diffuses in the internal space 26 and comes into contact with the platinum coating catalyst layer 32. The oxygen and hydrogen in contact with the platinum coating catalyst layer 32 are increased in reactivity by the catalytic action of platinum, and are in a so-called radicalized state. The radicalized hydrogen and oxygen react instantaneously at a temperature lower than the ignition temperature of the hydrogen mixed gas, and generate moisture without performing high-temperature combustion. This moisture gas is supplied downstream via the moisture gas outlet passage 25a.
[0007]
Similarly, in the reactor main body 21 of FIG. 6, hydrogen and oxygen, which are source gases supplied to the inside of the reactor main body 21 through the source gas supply passage 24 a, collide with the reflector 9 to cause an internal space. 26 is diffused. The diffused source gas hydrogen and oxygen are brought into a radicalized state by contacting with the platinum coating catalyst layer 32, and react instantly without generating high-temperature combustion as described above to generate moisture. To do.
[0008]
The reactor main body 21 having the structure shown in FIGS. 5 and 6 and the like can greatly reduce the size of the moisture generator, and has a high purity water in an amount exceeding 1000 cc / min under higher reactivity and responsiveness. As a result, it is possible to obtain a mixed gas of high-purity water and oxygen, which has attracted epoch-making attention in the field of semiconductor manufacturing technology.
Moreover, the reaction furnace main body 21 for generating water such as this is used in a temperature range where hydrogen and oxygen do not spontaneously ignite in the furnace (for example, 400 ° C.), and by generating water only by catalytic reaction, It is characterized by producing and supplying high-purity moisture safely.
[0009]
Furthermore, the inventors of the present application have made many developments in the past in order to increase the catalytic reaction efficiency in water generation using the above catalytic reaction. For example, Japanese Patent Laid-Open Nos. 10-270437 and 10- In No. 297907, the reaction rate of hydrogen and oxygen is increased by improving the structure of the reactor in order to reduce the residual hydrogen in the moisture gas. In JP-A-11-171503, the hydrogen flow rate to be supplied is gradually increased to increase the reaction efficiency between hydrogen and oxygen, and the residual hydrogen amount is reduced. Furthermore, in Japanese Patent Laid-Open No. 11-11902, the hydrogen supply efficiency is increased by delaying the hydrogen supply start time from oxygen and at the same time bringing the hydrogen supply end time earlier than oxygen.
As a result, the reactor main body 21 having the configuration shown in FIGS. 5 and 6 has a feature that it can generate and supply high-purity water with a residual hydrogen amount of nearly zero under high catalytic reaction efficiency. .
[0010]
[Problems to be solved by the invention]
However, in the semiconductor production line, there are many processes for supplying and processing moisture under reduced pressure (for example, several Torr). In this case, if hydrogen and oxygen decompressed from the source gas supply passage 24a are supplied to the reaction furnace main body 21, the ignition temperature of hydrogen is lowered, and hydrogen may spontaneously ignite in the reaction furnace.
[0011]
FIG. 7 is an ignition limit curve of a 2: 1 volume ratio H ₂ —O ₂ gas mixture in a spherical container having a radius of 7.4 cm. This curve is obtained from Chemical Handbook Basic Revised Edition 3 (Chemical Society of Japan, Maruzen) II-406, where the vertical axis indicates the total pressure of the mixed gas and the horizontal axis indicates the ignition temperature.
[0012]
Consider that the total pressure of the mixed gas of hydrogen and oxygen was reduced to several Torr when the internal temperature of the reactor was set to 400 ° C. From FIG. 7, the ignition temperature corresponding to a pressure of several Torr is about 400 ° C. Therefore, under this condition, the ignition temperature approaches the set temperature, so hydrogen spontaneously ignites in the reactor. If the set temperature is set higher, ignition will surely occur.
[0013]
Thus, as the total pressure of the mixed gas of hydrogen and oxygen decreases, the ignition temperature of hydrogen rapidly decreases. Even if the temperature is designed so that hydrogen does not ignite when the total pressure is high, when the total pressure decreases, there will be a situation where a sudden ignition occurs. When ignited in the reaction furnace, the flame flows back to the upstream side via the source gas supply passage 24a, and there is a risk of explosion of the hydrogen cylinder.
[0014]
The present invention completely suppresses the risk of ignition when the total pressure of the mixed gas of hydrogen and oxygen as described above is reduced, realizes a reduced supply of moisture gas, and at the same time keeps the internal pressure of the reactor for moisture generation high. Accordingly, it is a main object of the present invention to provide a safe reduced pressure type moisture generating and supplying apparatus capable of completely preventing spontaneous ignition of hydrogen.
[0015]
[Means for Solving the Problems]
The invention of claim 1 comprises a water generation reactor for generating a water gas by catalytic reaction from hydrogen and oxygen, and a decompression means provided on the downstream side of the water generation reactor. A depressurized moisture generation and supply device characterized in that the internal pressure in a reaction furnace is kept high at the same time that the moisture gas is depressurized and supplied downstream.
[0016]
A second aspect of the present invention is the reduced pressure type moisture generating and supplying apparatus according to the first aspect, wherein the pressure reducing means is an orifice or a valve, a capillary, or a filter.
[0017]
According to a third aspect of the present invention, there is provided a reactor main body in which the moisture generating reaction furnace is formed by combining an inlet side main body member having a source gas supply port and an outlet side furnace main body member having a moisture gas outlet in an opposing manner. An inlet-side reflector disposed in the internal space of the reaction furnace so as to face the gas supply port; an outlet-side reflector disposed in the internal space so as to face the moisture gas outlet; and the outlet It is a pressure reduction type | mold moisture generation supply apparatus of Claim 1 or Claim 2 formed from the platinum coating catalyst layer formed in the inner wall surface of a side furnace main body member.
[0018]
According to a fourth aspect of the present invention, there is provided a reactor main body formed by combining the moisture generating reaction furnace with an inlet side main body member having a source gas supply port and an outlet side furnace main body member having a moisture gas outlet facing each other. 3. A moisture generating reaction furnace comprising a reflector disposed in an internal space of the reactor main body and a platinum coating catalyst layer formed on an inner wall surface of the furnace main body member. This is a reduced pressure type moisture generating and supplying apparatus.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
As described above, there are two problems to be achieved by the present invention. First, high-purity moisture gas can be supplied to the downstream side at a low pressure, and second, the internal pressure of the reactor for moisture generation is kept high to maintain hydrogen. Is to keep the ignition temperature high. In this way, ignition is prevented by increasing the difference between the actually set temperature and the ignition temperature of the reactor that generates moisture.
[0020]
As a result of intensive studies to solve the above problems, the present inventors have come up with a method for simultaneously solving two kinds of problems. That is, if a pressure reducing means such as an orifice or a valve is arranged downstream of the moisture generating reactor, the moisture generating reactor generates moisture gas at a high pressure, and the moisture gas is throttled by the pressure reducing means, and the pressure is reduced to the downstream side. It becomes possible to supply with.
[0021]
For example, the set temperature of the moisture generation reactor is set to 350 ° C. When the total pressure of the mixed gas of hydrogen and oxygen is adjusted to 100 to 1000 Torr and supplied to the water generation reactor, it can be seen from FIG. 7 that the ignition temperature is 540 to 580 ° C. In this way, the difference between the ignition temperature and the set temperature reaches 190 to 230 ° C., and hydrogen cannot spontaneously ignite. Keeping this temperature difference large prevents hydrogen ignition and realizes safe supply of moisture gas.
[0022]
Hereinafter, embodiments of a reduced pressure type moisture generating and supplying apparatus according to the present invention will be described in detail with reference to the drawings.
FIG. 1 is a configuration diagram of an embodiment of a reduced pressure type moisture generating and supplying apparatus. Three types of gases, H ₂ , O ₂ , and N ₂ , flow in while being selected by valves V1, V4, and V7, and moisture is controlled through valves V3, V6, and V9 while the flow rate is controlled by mass flow controllers MFC1, MFC2, and MFC3. It is supplied to the reactor for generation WVG. Valves V2, V5, and V8 are exhaust valves.
[0023]
The moisture generation reactor WVG is shown in FIG. The pressure of the moisture gas generated in the reaction furnace WVG is measured by the pressure gauge P1 and recorded by the recorder R. The moisture gas is reduced by the pressure reducing means RM (orifice in FIG. 1), and sent to the process chamber C through the filter F while the residual hydrogen is measured by the hydrogen sensors S1 and S2. The residual hydrogen amount is also recorded in the recorder R. The area BA shown in the record is heated at 140 ° C. to prevent gas adsorption on the inner surface of the tube.
[0024]
The moisture gas sent from the filter F is subjected to component analysis by the mass analyzer M through the sampling valve SV. The process chamber C is, for example, a semiconductor manufacturing apparatus, and is pulled by a vacuum pump RP through a valve V10, and its internal pressure is measured by a pressure gauge P2. Unnecessary gas is exhausted by the valve 11.
[0025]
The gas pressure of the raw material gas entering the mass flow controllers MFC1 to MFC3 is 2 (kg / cm ² G). As a result of adjusting the flow rate, these flow rates are ₁ SLM for N ₂ , 0.2 to 1 SLM for H ₂ , O ₂ is 0.5-1 SLM. The internal pressure of the process chamber C is adjusted to 1 Torr with the vacuum pump RP. The diameter of the orifice used as the decompression means RM is 0.6 mm, and the internal temperature of the water generation reactor WVG is set to 350 ° C.
[0026]
FIG. 2 shows the N ₂ gas flow rate dependence of the reactor pressure for moisture generation. The vacuum pump RP is stopped, the valve 11 is opened, and the process chamber C is set to atmospheric pressure. In this state, the apparatus of FIG. 1 is purged with only N ₂ gas. It can be seen that when the N ₂ gas flow rate is increased in the range of 1000-5000 sccm, the reactor pressure increases linearly in the range of about 900-1900 Torr.
[0027]
Since the orifice as a pressure reducing means RM is disposed, increasing the flow rate of N ₂ gas, the flow control to the downstream side by the orifice, N ₂ gas is the reactor pressure increases to Todokotamari into the reactor. Since an increase in pressure occurs with N ₂ gas, naturally an increase in pressure can be expected with other mixed gases.
[0028]
FIG. 3 shows the H ₂ —O ₂ mixed gas flow rate dependence of the moisture generation reactor pressure. In FIG. 1, the vacuum pump RP is activated to set the pressure in the process chamber C to 1 Torr. The H ₂ gas flow rate is fixed at 1000 sccm, and the O ₂ gas flow rate is increased to 600-1500 sccm.
[0029]
The stoichiometric flow rate of O ₂ gas that reacts with 1000 sccm of H ₂ gas is 500 sccm, and the theoretical value of the generated water gas flow rate is 1000 sccm. However, the actual reaction does not work as theoretically, and as a result of a small amount of H ₂ gas remaining, the moisture gas becomes less than 1000 sccm. Further, in increasing the flow rate, the O ₂ gas flow rate without adverse effects is increased, and the total pressure of the H ₂ —O ₂ mixed gas is increased.
[0030]
As can be seen from FIG. 3, when the O ₂ gas flow rate is increased in the range of 600-1500 sccm, the reactor pressure increases linearly in the range of about 400-740 Torr. In this pressure range, it can be seen from FIG. 6 that the ignition temperature of hydrogen in the reaction furnace is about 560 ° C., and the ignition temperature is about 210 ° C. higher than the set temperature in the furnace of 350 ° C. Therefore, hydrogen cannot ignite in the reactor.
[0031]
FIG. 4 shows the unreacted H ₂ gas concentration when the O ₂ gas flow rate is changed in FIG. As shown in FIG. 3, even if the reaction is performed under oxygen-rich conditions, the amount of unreacted H ₂ gas is a very small amount of about 0.08%, and the inside of the reaction furnace can be maintained at a high pressure by the decompression means of the present invention. As a result, hydrogen ignition is strongly prevented by raising the ignition temperature, and moisture can be generated safely.
[0032]
In FIG. 1, an orifice is used as the pressure reducing means RM, but a valve may be used. Since the opening of the valve can be varied, the flow rate can be adjusted, and the pressure in the moisture generating reactor can be adjusted. The decompression means RM may be anything that has a throttling mechanism and can adjust the pressure, or that causes a pressure loss, and may be a known one such as a nozzle, a venturi tube, a capillary, or a filter.
[0033]
The present invention is not limited to the above-described embodiments, and includes various modifications, design changes, and the like within the technical scope without departing from the technical idea of the present invention.
[0034]
【The invention's effect】
According to the first aspect of the present invention, the depressurization means provided on the downstream side of the moisture generating reaction furnace can reduce the moisture gas and supply it to the downstream side, and the internal pressure of the reaction furnace can be kept high. Can be reliably prevented, and a safe and stable water supply can be realized.
[0035]
According to the invention of claim 2, pressure reduction and ignition prevention can be realized by a simple pressure reduction means called an orifice, and when a valve is used as the pressure reduction means, the degree of pressure reduction and ignition prevention can be variably adjusted only by opening and closing operations. .
[0036]
According to the invention of claim 3 and claim 4, since the water generation reaction of hydrogen and oxygen can be realized with high efficiency by the platinum coating catalyst layer, the amount of unreacted hydrogen contained in the moisture gas can be minimized, and the pressure reducing means At the same time, safety can be further enhanced.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of an embodiment of a reduced-pressure type moisture generating and supplying apparatus according to the present invention.
FIG. 2 is a graph showing the N ₂ gas flow rate dependency of moisture generation reactor pressure.
FIG. 3 is a graph showing the H ₂ —O ₂ mixed gas flow rate dependence of moisture generation reactor pressure.
4 is a graph showing the unreacted H ₂ gas concentration when the O ₂ gas flow rate is changed in FIG. 3;
FIG. 5 is a cross-sectional view showing an example of a water generation reactor.
FIG. 6 is a cross-sectional view showing another example of a moisture generating reactor.
FIG. 7 is an ignition limit curve of a H ₂ —O ₂ mixed gas having a volume ratio of 2: 1.
[Explanation of symbols]
21 is a reactor main body, 22 is an inlet side furnace main body member, 23 is an outlet side furnace main body member, 24 is a raw material gas supply joint, 24a is a raw material gas supply passage, 25 is a moisture gas extraction joint 25a is a moisture gas outlet passage , 26 is an internal space, 29a is an inlet side reflector, 29b is an outlet side reflector, 32 is a platinum coating catalyst layer, 32a is a barrier coating, 32b is a platinum coating, BA is a heating region, C is a process chamber, and F is a filter. , M is a mass analyzer, MFC1 to MFC3 are mass flow controllers, P1 and P2 are pressure detectors, R is a recorder, RM is a decompression means, RP is a vacuum pump, S1 and S2 are hydrogen sensors, SV is a sampling valve, V1 V11 is a valve, WVG is a reactor for moisture generation.

Claims (4)

The reactor is composed of a moisture generation reactor that generates moisture gas from hydrogen and oxygen by a catalytic reaction, and a decompression device provided downstream of the moisture generation reactor. A reduced pressure type moisture generating and supplying apparatus characterized in that the internal pressure in the reaction furnace is kept high at the same time as the supply to the side. The reduced pressure type moisture generating and supplying apparatus according to claim 1, wherein the pressure reducing means is one or more of an orifice, a valve, a capillary, and a filter. A reactor main body formed by combining the reactor for generating moisture with an inlet-side main body member having a raw material gas supply port and an outlet-side furnace main body member having a moisture gas outlet, and the inside of the reactor main body. An inlet-side reflector disposed in the space so as to face the gas supply port, an outlet-side reflector disposed in the inner space so as to face the moisture gas outlet, and an inner wall surface of the outlet-side furnace body member The reduced pressure type moisture generation and supply device according to claim 1 or 2, wherein the reactor is a moisture generation reaction furnace comprising a platinum coating catalyst layer formed on the substrate. A reactor main body formed by combining the reactor for generating moisture with an inlet side main body member having a raw material gas supply port and an outlet side furnace main body member having a moisture gas outlet, and the inside of the reactor main body. The reduced pressure type moisture generating and supplying apparatus according to claim 1 or 2, wherein the reactor is a moisture generating reaction furnace comprising a reflector disposed in a space and a platinum coating catalyst layer formed on an inner wall surface of the furnace body member. .

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