IL141988A - Process for supplying moisture at low flow rate - Google Patents

Abstract

A process of supplying moisture or a mixture of moisture with oxygen from a reactor to a semiconductor manufacturing line at a set, low flow rate, comprising feeding, at a temperature lower than the ignition point, oxygen and hydrogen into a reactor provided with a platinum coating on an interior wall where the oxygen reacts instantaneously with the hydrogen at a temperature lower than the ignition point to produce moisture without undergoing combustion at a high temperature; wherein the flow rate of hydrogen supplied to said reactor is controlled by means of a flow controller in such a way that while oxygen is kept flowing at a set flow rate, the supply of hydrogen to the reactor is started and gradually increased and reaches a specific set level in a specific time after the start of the feeding of hydrogen, and wherein the flow controller is so controlled that the flow rate of hydrogen is raised at an approximately fixed rate of increase and reaches a specific set level in a specific time, wherein said specific time for the set flow rate level to be reached is in the range of one to ten seconds. 2001 ז' באב התשס" ד - July 25, 2004

Description

PROCESS OF SUPPLYING MOISTURE AT SMALL FLOW RATE Field of the Invention The present invention relates to an improvement of a small flow rate moisture feeding system for use especially in the production of semiconductors by the low moisture oxidation technique. More particularly, the present invention relates to accurately controlled generation and supplying of moisture in very small quantities.

Background of the Invention In the manufacture of semiconductor elements, the conventional, so-called "dry" O2 oxidation technique for coating silicon oxide ilm by thermal oxidation is now largely replaced by the moisture oxidation technique, which is also called the "wet" 02 oxidation method. That is because the silicon oxidation film formed by the moisture oxidation technique is superior to that obtained by the dry O2 oxidation technique in properties such as insulation strength and masking effect.

Oxide film coating by the aforesaid moisture oxidation technique uses a mixed gas with a moisture content (H2O/O2) of, generally, some 20 to 30 percent. The amount of moisture to be mixed into 02 is some 200 to 2,000 seem or cubic centimeters, in terms of the standard state. That is, a relatively large quantity of moisture is fed from the reactor for generation of moisture to the semiconductor manufacturing facilities.

Fig. 6 shows an example of the apparatus for generation of moisture used in the moisture oxidation technique in practice. In Fig. 6, H2 represents hydrogen; O2, oxygen; N2, nitrogen gas for purging the system; MFC1 to MFC5, mass controllers; VI to V5, valves; Tl to T6, thermocouples for measuring the temperature; CVl to CV5, check valves; Fl to F3, filters; HO and HI, gas preheater coils; MXl, 02-H2 mixer; MX2, 02-moisture mixer; 1, the reactor for generation of moisture, and SM, processing equipment, such as semiconductor manufacturing facilities.

As shown in Fig. 7, the aforesaid reactor 1 for generation of moisture comprises reactor structural components 2 and 3 provided with a gas supply joint 4 and a moisture gas take-out joint 5; a reflector 9 on the inlet side provided inside the reactor 1 and opposite a gas feed passage 4a of the reactor structural component 2; a reflector 12 on the outlet side provided inside the reactor 1 and opposite a moisture gas outlet passage 5a of the reactor structural component 3; a filter 10 provided in the middle of the reactor 1 and a platinum-coated catalyst layer 13, provided on the inside wall of the reactor structural component 3.

The platinum-coated catalyst layer 13, which is formed on the inside wall surface of the reactor structural component 3, is of the double layer construction having a barrier coating 13a with a platinum coating 13b formed thereupon. The barrier coating 13a is formed of a nitride such as Ti , on which the platinum coating 13b is fixed by a vapor deposition technique or an ion coating technique.

Hydrogen and oxygen are fed into the reactor 1 through the gas feed passage 4a, diffused by gas diffusion means 8 comprising the inlet reflector unit 9, the filter 10 and the outlet reflector unit 12, and then come in contact with the platinum-coated catalyst layer 13. Upon coming in contact with the platinum-coated catalyst layer 13, hydrogen and oxygen are enhanced in reactivity by the catalytic action and come to be what is called "the radicalized state." Radicalized hydrogen and oxygen instantaneously react with each other at a temperature lower than the ignition point, to produce moisture without undergoing combustion at a high temperature.

The flow rates of H2 and 02 which are fed into the reactor 1 are set properly to, for example, 1,000 sccm:600 seem or so, but generally, a 20 percent 02-rich material gas mixture of H2 and O2 is sent into the reactor. The gas supply pressure of O2 and ¾ is set to 1.0 to 3.0 kg/cm2 to produce some 1,000 scm of moisture. The reactor 1 for generation of moisture is 114 mm in outside diameter, some 31 mm in thickness and 86 cm3 in interior space, with 99 cm2 in a platinum-coated catalyst layer area. Though very small in size, as shown, this reactor can turn out over 1,000 seem of moisture.

On the outlet side of the reactor is provided the aforementioned O2-moisture mixer MX2, where the moisture as generated can be mixed with O2 in any desired radio and diluted.

Fig. 6 illustrates an operation in which a 20 percent oxygen-rich material gas mixture is fed into the reactor 1. Needless to say, the reactor 1 can be operated with a hydrogen-rich material gas mixture. In such an arrangement, an H2-moisture mixer MX1 is provided instead of the 02-moisture mixer MX2, as necessary.

The aforesaid gas preheater coils HO and HI are for heating the material gas mixture or O2 respectively, at not higher than some 200°C. The reactor 1 is also provided with a heater and, as necessary, a cooler, so that if the reaction heat pushes up the temperature in the reactor in operation to over 500°C (which rarely happens), the cooler will be activated to bring down the temperature below 500°C. In addition, the mixture in the mixer MX2 provided near the outlet of the reactor is constantly maintained at some 120°C, to prevent ¾O from condensing on the pipe wall. A heater is provided, as necessary.

Prior to starting up the reactor 1 for generation of moisture, such equipment as the mass flow controllers MFC1 to MFC5 and temperature controllers are first prepared for operation, and the valves V2 and V5 are opened, and the valves VI, V3 and V4 are closed to purge the system with nitrogen gas.

Then, the valves V2 and V5 are closed. At the same time, or after lapse of a certain time, V3 and V4 are opened to first feed O2 into the system, and at the same time that O2 starts to be fed, or when a certain time has lapsed after that, VI is opened to feed ¾ into the system.

In contact with the platinum-coated catalyst layer in the reactor 1, O2 and ¾ are radicalized to react with each other to produce some 1,000 seem of moisture gas, which is sent out to semiconductor manufacturing facilities SM.

It is noted that the mass flow controllers FC1 to MFC5 are generally so constituted that the flowing gas reaches a set flow rate as soon as possible. That is, the flow rate of the flowing O2 or J¾ gas rises to a set level within some one second after the start of the feeding of the gas.

The moisture generator illustrated in Fig. 6 can produce over some 1,000 scm of high purity water. The amount of moisture to be generated and supplied can be controlled by regulating the feeding of 02 and ¾ relatively easily with high precision. Thus, the generator is excellent in practical usefulness.

However, that moisture generator still has many problems yet to be solved. Of those, the foremost problem is control of the flow rate of moisture when it is to be generated in very small quantities.

In recent years, what is called the "low moisture oxidation technique" is being put to wide practical application in silicone oxide film coating by moisture oxidation. This low moisture oxidation is practiced using the mixture gas of 02 and ¾0 with the moisture content of 1,000 ppm - 2 percent.

The moisture generator illustrated in Fig. 6, too, is required to regulate the generation of moisture at a very small rate, that is, one to 50 seem, with high precision.

With the moisture generator outlined in Fig. 6, a variety of inconveniences arises, and it is virtually impossible to control the generation of moisture at such a small rate, which will be described later.

Shown in Fig. 8 is a testing apparatus the inventors have developed to test the response characteristics or responsiveness of the reactor 1 for generation of moisture. Experiments were conducted using this testing apparatus and the response characteristics of the reactor 1 for generation of moisture were determined with the production of moisture kept at very low levels.

In Fig. 8, MFCl to MFC3 indicate mass flow controllers; VI to V6, valves; SV, a suction-regulating valve; E, a quadrupole mass spectrometer (Q-mass spectrometer); P, a vacuum pump (rotary pump); D, a turbo molecular pump; and R, a moisture-collecting reservoir. Moisture is condensed at room temperature, and the condensed moisture is collected. The mass flow controllers MFCl to MFC3 are the so-called "quick-start" type mass flow controllers and are so designed that the level of H2 and O2 will reach a specific set flow rate as soon as possible.

For determination of the start-up response characteristics of the reactor 1 for generation of moisture, the flow rates of H2, 02 and N2 were first set to the levels in four cases as shown below, by means of the mass flow controllers MFCl to MFC3. In each case, the concentration of H2, 02 and N2 in the generated moisture and the generated amount of H2O were determined using the Q-mass spectrometer E. The valves VI to V3 were actuated this way: At the start-up of the moisture generator 1, the valve V3 was closed and V2 was opened. Two seconds later, VI was opened to produce moisture for one minute. When the moisture generation was to be ended, the valve VI was closed, and two seconds after that, the valve V2 was closed and the valve V3 was opened to feed N2 to the reactor 1. On the other hand, part of the gas flowing out of the reactor 1 was led into the Q-mass spectrometer E and deteraiination was made of the concentration of ¾, O2 and N2 in the generated moisture and the generated amount of H20, at a measurement interval of about one second.

Case 1: ¾ = 5 seem; O2 = 1,075 seem; N2 = 5,000 scm Case 2: H2 = 10 seem; O2 = 1 ,075 seem; N2 = 5,000 scm Case 3: H2 = 20 seem; O2 = 1 ,075 seem; N2 = 5,000 scm Case 4: H2 = 50 seem; O2 = 1,075 seem; N2 = 5,000 scm The Q-mass spectrometer used was the model MSQ-150A Quadrupole Mass Analyzer manufactured by ULVAC Corporation, Japan. The supply pressure was set to 2 kgf/cm2 for ¾, 2kgf/cm2 for O2 and 7 kgf/cm2 for N2, all gauge pressures.

Fig. 9 shows the results of the tests carried out by the testing apparatus shown in Fig. 8 to test the moisture generation response characteristics of the prior art moisture generator. As illustrated in Fig. 9, the amount of generated moisture peaked at P is the same in every case.

In the arrangement of the prior art moisture generator as shown in Fig. 6, the amount of moisture generated is almost the same in the initial stage when the moisture generation is small. In other words, it was shown that it was impossible to control the concentration of H20 to be mixed, that is, the flow rate of H20.

The reason why all the four cases 1 to 4 peak at almost the same H20 level in the moisture generation response characteristics curve may be this: some H2 remains trapped in the pipe line, the mass flow controller MFC1, the valve VI and other parts in the hydrogen gas supply system when a cycle is over. And when the valve VI is opened in the next cycle, this remnant H2 flows into the reactor 1 and reacts and turns into H20, sending up the moisture generation to the peak P.

In Fig. 9, the concentration curve of H2 peaks at That is probably because part of H20 led into the Q-mass spectrometer E will decompose into H2+ ions in a gas ionizer within the spectrometer E and those ions will be measured together.

Summary of the Invention The present invention addresses those problems encountered with the prior moisture generator. That is, the prior art cannot control the amount of moisture generation or the flow rate of moisture when the moisture generation per unit time is very small, and it is impossible to regulate H20 in the H20 mixture gas to be supplied to the respective processes in the semiconductor manufacturing facilities.

It is an object of the present invention to provide a process for feeding moisture at a very small flow rate which permits control with high precision of the flow and feeding of moisture to the semiconductor manufacturing line at very small flow rates.

Therefore, the invention provides a process for supplying moisture at a small flow rate to be used in an apparatus for generation of moisture, in which hydrogen and oxygen are fed into a reactor provided with a platinum coating on the wall in the interior space, enhanced in reactivity by the platinum catalytic action and caused to instantaneously react with each other at a temperature lower than the ignition point to produce moisture without undergoing combustion at a high temperature, wherein the flow rate of hydrogen supplied to said reactor is controlled by means of a flow controller in such a way that, while oxygen is kept flowing at a set flow rate, the supply of hydrogen to the reactor is started and gradually increased, and reaches a specific set level in a specific time after the start of the feeding of hydrogen, thereby producing and supplying moisture or a mixture of moisture with oxygen from the reactor to a semiconductor manufacturing line at a set flow rate.

The invention further provides a process of supplying moisture at a small flow rate to be used in an apparatus for generation of moisture, in which hydrogen and oxygen are fed into a reactor provided with a platinum coating on the wall in the interior space, enhanced in reactivity by the platinum catalytic action and caused to instantaneously react with each other at a temperature lower than the ignition point to produce moisture without undergoing combustion at a high temperature, wherein the flow rate of oxygen supplied to the reactor is controlled by means of a flow controller in such a way that while hydrogen is kept flowing at a set flow rate, the supply of oxygen to the reactor is started and gradually increased, and reaches a specific set level in a specific time after the start of the feeding of oxygen, thereby producing and supplying moisture or a mixture of moisture with hydrogen from the reactor to a semiconductor manufacturing line at a set flow rate.

In addition, the invention provides a process for supplying moisture at a small flow rate to be used in an apparatus for generation of moisture in which hydrogen and oxygen are fed into a reactor provided with a platinum coating on the wall in the interior space, enhanced in reactivity by the platinum catalytic action and caused to instantaneously react with each other at a temperature lower than the ignition point to produce moisture without undergoing combustion at a high temperature, wherein an escape pipe provided with an escape valve is branched out from the outlet side of the reactor or moisture generator and first, with the escape valve left open, hydrogen and oxygen are fed into the reactor at specific rates to produce in advance a specific amount of moisture in the reactor and then, with the escape valve closed, moisture or its mixture with oxygen or hydrogen is supplied from the reactor to the semiconductor manufacturing line at a set flow rate.

The invention still further provides a process for supplying moisture at a small flow rate to be used in an apparatus for generation of moisture in which hydrogen and oxygen are fed into a reactor provided with a platinum coating on the wall in the interior space, enhanced in reactivity by the platinum catalytic action and caused to instantaneously react with each other at a temperature lower than the ignition point to produce moisture without undergoing combustion at a high temperature, wherein an escape pipe provided with an escape valve is branched out from the outlet side of a flow rate controller for control of the flow rate of hydrogen supplied to the reactor and while oxygen is being supplied at a set flow rate, the escape valve is first opened and hydrogen is fed, thereby lowering the pressure on the secondary side of the flow rate controller, and then the escape valve is closed to feed hydrogen into the reactor, whereby moisture or a mixture of moisture with oxygen is supplied from the reactor to the semiconductor manufacturing line at a set flow rate.

In addition, the invention further provides a process of supplying moisture at a small flow rate to be used in an apparatus for generation of moisture in which hydrogen and oxygen are fed into a reactor provided with a platinum coating on the wall in the interior space, enhanced in reactivity by the platinum catalytic action and caused to instantaneously react with each other at a temperature lower than the ignition point to produce moisture without undergoing combustion at a high temperature, wherein an escape pipe provided with an escape valve is branched off from the outlet side of a flow rate controller for control of the flow rate of oxygen supplied to the reactor, and wherein while hydrogen is being supplied at a set flow rate, the escape valve is first opened and oxygen is fed, thereby lowering the pressure on the secondary side of the flow rate controller, and then the escape valve is closed to feed oxygen into the reactor, whereby moisture or a mixture of moisture with hydrogen is supplied from the reactor to the semiconductor manufacturing line at a set flow rate.

Brief Description of the Drawings The invention will now be described in connection with certain preferred embodiments with reference to the following illustrative figures so that it may be more fully understood.

With specific reference now to the figures in detail, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of the preferred embodiments of the present invention only, and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the invention. In this regard, no attempt is made to show structural details of the invention in more detail than is necessary for a fundamental understanding of the invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the invention may be embodied in practice.

Fig. 1 is a system diagram of a moisture generator to practice the first embodiment of the present invention; Fig. 2 is a schematic diagram showing the experiment arrangement to test the response characteristics of the apparatus for generation of moisture used to practice the first embodiment of the present invention; Fig. 3 depicts moisture generation response characteristics curves showing the results of the response characteristics test by the testing arrangement shown in Fig. 2; Fig. 4 is a system diagram of a moisture generator to practice the second embodiment of the present invention; Fig. 5 is a system diagram of a moisture generator to practice the third embodiment of the present invention; Fig. 6 is a system diagram of an example of the apparatus for generation of moisture developed earlier; Fig. 7 is a vertical section of an example of the apparatus for generation of moisture developed earlier, Fig. 8 is a schematic diagram showing an experiment arrangement to test the response characteristics of the apparatus for generation of moisture outlined in Fig. 6, and Fig. 9 depicts moisture generation response characteristics curves showing the test results of the response characteristics of the apparatus for generation of moisture outlined in Fig. 6.

Description of Preferred Embodiments Now, there will be described the embodiments of the present invention with reference to the drawings.

Embodiment 1 Fig. 1 is a system diagram of a moisture generator to practice the first embodiment of the present invention.

In Fig. 1, the reference letter H2 indicates hydrogen; 02, oxygen; N2, nitrogen; MFCl to MFC5, flow controllers such as mass flow controller; VI to VIO, valves; Tl to T6, thermocouples for measurement of temperature; CVl to CV5, check valves; Fl to F3, filters; HI and H2, gas heater coils; MX1, 02-H2 mixer; MX2, 02-H20 mixer; 1, a reactor for generation of moisture; SM, semiconductor manufacturing facilities, such as an oxidation chamber to which the generated moisture is supplied. This moisture generator is identical with the one shown in Fig. 6 except that this generator is provided with valves 6 to 10 and uses a gradually-opening or slow-start mass flow controller MFCl as mass flow controller.

That is, the mass flow controller MFCl on the hydrogen gas supply line in the present embodiment is so constituted that after hydrogen gas ¾ has started to be supplied to the primary or upstream side at a pressure of 1.0 to 3.0 kgf/cm2, the flow rate of H2 on the secondary or downstream side is gradually increased and reaches a specific level in some one to ten seconds, in what is called the slow-start type. Also, a valve V8 is provided on the inlet side of the mass flow controller MFCl on the hydrogen supply line. By connecting this valve V8 directly with the mass flow controller MFCl, the dead space between the two is mmimized.

To start up the reactor 1 for generation of moisture, such components as the mass flow controllers MFCl to MFC5 and temperature controllers are first prepared for operation, and then the valves V2, V7, V5 and V6 are opened, and the valves VI, V8, V3, V9, V4 and V10 are closed to purge the system with N2.

After that, the valves V2 and V5 are closed, and at the same time, or after lapse of a certain time, the valves V3, V9, V4 and V10 are opened to feed 02 into the system.

At the same time as O2 starts to be fed, or a specific time (some one to three seconds) after that, the valves VI and V8 are opened to feed ¾ in the system.

As the valves VI and V8 are opened, ¾ begins to flow into the reactor 1 for generation of moisture. As mentioned earlier, however, the mass flow controller MFCl is of the slow-start type, and H2 which flows through the valve VI to mix with O2 is not increased as suddenly as in the prior art system, but gradually increases according to the flow increase rate set by the mass flow controller MFCl.

In the present embodiment, the H2 flow increase rate set by the aforesaid mass flow controller MFCl is so detennined that the set flow rate - about 1 seem to about 50 seem - will be reached in some one to ten seconds. Therefore, remaining H2 trapped in inside spaces of the mass flow controller MFCl, pipe line P and the valve VI will not be pushed into 02 all at once.

Fig. 3 shows the moisture generation response characteristics curves obtained with the reactor 1 for generation of moisture in the experiment arrangement shown in Fig. 2, in which the slow-start type mass controller was used as mass flow controller MFCl. In this experiment, the valves were actuated this way: At the startup, the valves V2 and V7 were closed, while the valves V3 and V9 were opened. Two seconds later, the valves VI and V8 were opened. In ending the operation, the valves VI and V8 were closed, and two seconds later the valves V3 and V9 were closed and the valves V2 and V7 were opened.

The other conditions, mcluding the amount of H2 supplied, were the same as those in the testing of the response characteristics shown in Fig. 9, and in addition, flow increase rate detenriined by the mass flow controller MFC1 was so set that the flow rate of H2 would increase and reach the set levels of 5, 10, 20 and 50 seem from 0 seem in some 5 seconds.

It is confirmed that in the operation by the process of supplying moisture in the first embodiment of the present invention, the initial generation of H20 is regulated at the respective set levels - 5 seem, 10 seem, 20 seem or 50 seem, as is clear from Fig. 3. Thus, the moisture generation, that is, the flow rate of the moisture supply to semiconductor manufacturing line can be controlled with high precision.

The first embodiment of the present invention as shown in Fig. 1 and Fig. 2 relates to what is called the "oxygen-rich generation of moisture," in which a relatively large amount of O2 and a relatively small amount of H2 are fed into the reactor 1 and a rnixture of O2 and moisture flows out of the moisture outlet it is confirmed that the hydrogen-rich generation of moisture in which a relatively large amount of H2 and a relatively small amount of 02 are fed into the reactor 1 and a rnixture of H2 and moisture is taken out of the moisture outlet, too, can be controlled with high precision as in the oxygen-rich operation, even when the moisture generation is small at 5 seem to 50 seem or so. This is accomplished by so regulating the supply of 02 using the slow-start or gradually opening flow controller that the flow rate reaches a specific flow level from 0 in a certain time - one to ten seconds.

In the embodiment in Fig. 1 and Fig. 2, a known mass flow controller is used. The flow controller may be of any type, including a pressure-type flow controller.

The first embodiment furthermore relates to the oxygen-rich generation of moisture. Needless to say, the present invention is not limited to that, but is also applicable to the operation in which ¾ and O2 are fed into the reactor 1 at a ratio of 2:1 and almost moisture alone is allowed to flow out of the moisture outlet.

Embodiment 2 Fig. 4 shows the configuration of the apparatus for generation of moisture used in the second embodiment of the present invention. In this second embodiment, a branch pipe S is provided on the moisture outlet side of the apparatus for generation of moisture, and an escape valve 13 is mounted on the branch pipe S. Switch-over valves VI 1 and V12 and a purging pipe Pn are provided immediately at the upstream side of the semiconductor manufacturing line SM. The arrangements in Fig. 4 are identical with those in Fig. 1, except that the apparatus for generation of moisture of the second embodiment is provided with the aforesaid branch pipe S, escape valve V13, switch-over valves VI 1 and VI 2, and purging pipe Pn. Description of the duplicated parts is omitted.

Referring to Fig. 4, N2 is fed to the semiconductor manufacturing line SM through the purging pipe Pn for the N2 purging. Before moisture is supplied to the semiconductor manufacturing line SM, specific amounts of 02 and ¾ are fed into the reactor for generation of moisture. The amount of moisture generated in the start-up of moisture generation, which is equivalent to the volume produced at the peak point of moisture as generated, is discharged through the escape valve V13 which is left open.

When the concentration of generated moisture has been stabilized, the aforesaid escape valve V13 is closed and the switch-over valve VI 1 is closed and the switch-over valve V12 is opened to lead generated moisture to the semiconductor manufacturing line SM at a specific rate.

In the present embodiment, the consumption of 02 and H2 rises because excessive moisture produced is discharged before the supply of moisture to the semiconductor manufacturing line SM is started. But the flow of moisture to the semiconductor manufacturing line SM can be controlled with very high precision.

Embodiment 3 Fig. 5 shows the arrangement of the apparatus for generation of moisture used in the third embodiment of the present invention.

In the third embodiment of the present invention, a branch pipe S is connected to the line on the outlet side of the mass flow controller MFCl for feeding hydrogen, and an escape valve V14 is provided on the branch pipe.

Before moisture begins to be generated, H2 trapped in the inside spaces of a valve V8, mass flow controller MFCl and valve VI is discharged through the escape valve VI . When the flow of H2 has been regulated to a specific level of H2 to be fed to the reactor 1, the escape valve V14 is closed to lead H2 into the reactor 1 for generation of moisture.

In the present embodiment, the escape valve 13 is left open beforehand. This way, excessive pressure of H2 trapped in the mass flow controller MFCl and the pipe line is discharged almost completely. So, when H2 is fed into the reactor 1 for generation of moisture, there will be no sudden rush of H2 into the reactor 1 as in the apparatus for generation of moisture as in Fig. 6.

That is, when the flow of H2 has been stabilized at a specific flow level preset by the mass flow controller MFCl, ¾ is fed into the reactor 1 through a valve VI. Therefore, the flow of moisture from the reactor 1 can be controlled with very high precision even if the flow is very small.

In the embodiment shown in Fig. 5, the so-called oxygen-rich moisture generation is described. It goes without saying that just as the first embodiment shown in Figs. 1 and 2, the process of the embodiment shown in Fig. 5 is applicable to the so-called hydrogen-rich moisture generation and also the operation in which ¾ and 02 are fed at the ratio of 2: 1 to produce and discharge almost only moisture out of the moisture outlet.

In case of moisture generation under the hydrogen rich condition, a branch pipe S is provided on the downstream side of a flow controller MFC3 for (¼. Excessive pressure of O2 trapped between the flow controller MFC3 and the valve V3 is discharged in advance through the branch pipe S and the escape valve. Sudden flow of O2 into the reactor 1 is prevented that way when the feeding of O2 is started. When the flow of 02 has been stabilized to a specific level, 02 is introduced into the reactor 1.

It is confirmed that this way, the flow of moisture can be controlled with very high precision even when the supply of moisture is very small in a hydrogen-rich generation.

The present invention, as described and claimed herein, is so configured that the feeding of hydrogen into the reactor for generation of moisture is gradually increased to a specific level by means of a flow controller. That precludes possible sudden rush into the reactor of hydrogen trapped in inside spaces of the flow controller and hydrogen pipe line which occurs when fresh hydrogen is supplied to the inlet side of the flow controller. That is, there will be no concern that the generation of moisture will rise out of control if the generated amount is very small. Thus, the production of moisture, though very small, can be controlled with very high precision.

The present invention, as described and claimed herein, is so configured that the feeding of oxygen into the reactor for generation of moisture is gradually increased to a specific level by means of a flow controller in the same manner as described above. Therefore, the production of moisture can be controlled with very high precision, even if a very small amount of moisture is generated under the hydrogen-rich condition.

The present invention, as described and claimed herein, is so configured that moisture is first generated in the reactor for generation of moisture and an amount of moisture produced at the peak point of moisture generation in the initial stage of the operation is discharged to the outside through the escape valve. The supply of moisture to the line SM begins when the moisture generation has been stabilized. Thus, the production of moisture, though very small, can be controlled with very high precision.

The present invention, as described and claimed herein, is so configured that a branch pipe to permit hydrogen to escape is provided on the outlet side of the flow controller which controls the flow of hydrogen. An escape valve is left open before hydrogen is fed into the inlet side of the reactor for generation of moisture, so that excessive pressure of hydrogen trapped inside is released through the escape valve. That can easily prevent the hydrogen remnants from suddenly flowing into the reactor, as opposed to the prior art Under this arrangement, there will arise no peak of moisture concentration in the initial stage any more, and even if moisture of a small amount is generated under the oxygen-rich condition, the supply to the semiconductor manufacturing line can be controlled with high precision.

The present invention, as described and claimed herein, is so configured that a branch pipe to allow oxygen to escape is provided on the outlet side of the flow controller which controls the feeding of oxygen. As described, the oxygen remnants are prevented from rushing into the reactor. As a result, it is possible to control an amount of moisture as generated with an extremely high precision, even if moisture of a small amount is generated under the hydrogen-rich condition.

As illustrated, the present invention is highly practical.

Claims (8)

20 141 ,988/2 WHAT IS CLAIMED IS:

1. A process of supplying moisture or a mixture of moisture with oxygen from a reactor to a semiconductor manufacturing line at a set, low flow rate, comprising feeding, at a temperature lower than the ignition point, oxygen and hydrogen into a reactor provided with a platinum coating on an interior wall whereby the oxygen reacts instantaneously with the hydrogen at a temperature lower than the ignition point to produce moisture without undergoing combustion at a high temperature; wherein the flow rate of hydrogen supplied to said reactor is controlled by means of a flow controller in such a way that while oxygen is kept flowing at a set flow rate, the supply of hydrogen to the reactor is started and gradually increased and reaches a specific set level in a specific time after the start of the feeding of hydrogen, and wherein the flow controller is so controlled that the flow rate of hydrogen is raised at an approximately fixed rate of increase and reaches a specific set level in a specific time, wherein said specific time for the set flow rate level to be reached is in the range of one to ten seconds.

2. A process of supplying moisture or a mixture of moisture with hydrogen from a reactor to a semiconductor manufacturing line at a set, low flow rate, comprising feeding, at a temperature lower than the ignition point, oxygen and hydrogen into a reactor provided with a platinum coating on an interior wall whereby the oxygen reacts instantaneously with the hydrogen at a temperature lower than the ignition point to produce moisture without undergoing combustion at a high temperature; wherein the flow rate of oxygen supplied to said reactor is controlled by means of a flow controller in such a way that while hydrogen is kept flowing at a set flow rate, the supply of oxygen to the reactor is started and gradually 21 141 ,988/2 increased and reaches a specific set level in a specific time after the start of the feeding of oxygen, and wherein the flow controller is so controlled that the flow rate of oxygen is raised at an approximately fixed rate of increase and reaches a specific set level in a specific time, wherein said specific time for the set flow rate level to be reached is in the range of one to ten seconds.

3. A process of supplying moisture from a reactor to a semiconductor manufacturing line at a low flow rate, comprising feeding, at a temperature lower than the ignition point, oxygen and hydrogen into a reactor provided with a platinum coating on an interior wall whereby the oxygen reacts instantaneously with the hydrogen at a temperature lower than the ignition point to produce moisture without undergoing combustion at a high temperature wherein an escape pipe provided with an escape valve is branched out from an outlet side of the reactor and, first, with the escape valve open, oxygen and hydrogen are fed into the reactor at specific rates to produce in advance a specific amount of moisture in the reactor and, subsequently, with the escape valve closed, moisture or a mixture of moisture with oxygen or hydrogen is supplied from the reactor to the semiconductor manufacturing line at a set flow rate.

4. A process of supplying moisture from a reactor to a semiconductor manufacturing line at a low flow rate, comprising feeding, at a temperature lower than the ignition point, oxygen and hydrogen into a reactor provided with a platinum coating on an interior wall whereby the oxygen reacts instantaneously with the hydrogen at a temperature lower than the ignition point to produce moisture without undergoing combustion at a high temperature wherein an escape pipe provided with an escape valve is branched off from an outlet side of a flow rate controller for control of the flow rate of hydrogen supplied to the reactor and, while oxygen is being supplied at a set flow •β 22 141 ,988/2 rate, the escape valve is first opened and hydrogen is fed, thereby lowering the pressure on the secondary side of the flow rate controller and, subsequently, the escape valve is closed to feed hydrogen into the reactor, whereby moisture or a mixture of moisture with oxygen is supplied from the reactor to the semiconductor manufacturing line at a set flow rate.

5. A process of supplying moisture from a reactor to a semiconductor manufacturing line at a low flow rate, comprising feeding, at a temperature lower than the ignition point, oxygen and hydrogen into a reactor provided with a platinum coating on an interior wall whereby the oxygen reacts instantaneously with the hydrogen at a temperature lower than the ignition point to produce moisture without undergoing combustion at a high temperature wherein an escape pipe provided with an escape valve is branched off from an outlet side of a flow rate controller for control of the flow rate of oxygen supplied to the reactor and, while hydrogen is being supplied at a set flow rate, the escape valve is first opened and oxygen is fed, thereby lowering the pressure on the secondary side of the flow rate controller and, subsequently, the escape valve is closed to feed oxygen into the reactor, whereby moisture or a mixture of moisture with hydrogen is supplied from the reactor to the semiconductor manufacturing line at a set flow rate.

6. A process of supplying moisture or a mixture of moisture with oxygen from a reactor to a semiconductor manufacturing line according to claim 1, substantially as hereinbefore described and with reference to the accompanying drawings. 23 141,988/1

7. A process of supplying moisture or a mixture of moisture with hydrogen from a reactor to a semiconductor manufacturing line according to claim 2, substantially as hereinbefore described and with reference to the accompanying drawings.

8. A process of supplying moisture from a reactor to a semiconductor manufacturing line according to claim 3, substantially as hereinbefore described and with reference to the accompanying drawings. for the Applicant: WOLFF, BREGMAN AND GOLLER by: J ? „ / ^