JPH11188374A - Ozone water manufacturing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prepare ozone water with high purity being utilized for cleaning in a semiconductor manufacturing field, etc., such as integrated circuits and contributing to decrease in processing cost for waste liq. and to prevent environmental disruption from occurring. SOLUTION: An ozone water manufacturing apparatus is provided with an ejector 60, a storing tank 70, a pipeline 71 connecting this storing tank 70 with the ejector 60, a valve means 90 and a forwarding pipe 73 for forwarding ozone water to an aimed point. The ejector 60 injects pure water and sucks ozone gas. The storing tank 70 stores a gas-liq. mixed phase generated by suction of the pure water and the ozone gas of the ejector 60. The valve means 90 vents a gas phase separated among the above described gas-liq. mixed phase in the storing tank 70. Among these constitutional members, those members which are brought into contact with the above described mixed phase or the ozone water are prepd. of an ozone-resistant material. In addition, a liq. level meter 78 is made into one which can non-contactly measure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ozone water producing apparatus for producing high-purity ozone water by injecting ozone gas into pure water.

[0002]

2. Description of the Related Art Integrated circuits (IC, LSI, VLSI, etc.)
In a manufacturing process of a semiconductor or a liquid crystal device, a highly clean cleaning is required. For example, when cleaning a silicon wafer for semiconductor, a natural oxide film on a silicon substrate,
Alternatively, in order to wash and remove dust and metal powder and the like attached to the silicon substrate, they are sequentially washed with hydrofluoric acid and a hydrogen peroxide solution, ammonia and a hydrogen peroxide solution, and a strong acid.
A cleaning method called so-called RCA cleaning has been conventionally used.

However, in the RCA cleaning, various kinds of chemicals as described above are used, so that waste liquids must be properly treated. Such waste liquid directly leads to environmental pollution if there is any defect in the treatment, and thus the labor and cost required for this treatment are increased. Therefore, there has been a demand for a cleaning means which does not use the above-mentioned chemical solution, in other words, which can easily treat waste liquid without causing environmental pollution.

As a cleaning means satisfying the above-mentioned demands, cleaning using ozone water has been proposed. That is, the above-mentioned ozone water has attracted attention as a cleaning means instead of the above-mentioned RCA cleaning because it does not require waste liquid treatment due to its strong oxidizing power and the property of self-decomposition to return to oxygen. In the case of cleaning using the above-mentioned ozone water, it is known that a cleaning effect similar to that of the conventional RCA cleaning can be obtained only by this ozone water and hydrofluoric acid treatment step.

The following describes ozone and ozone water.
Let me explain briefly. First, ozone is a gas having an oxidizing power next to fluorine, and its production method is usually a method in which oxygen gas is activated by a discharge electrode and a method in which water is electrolyzed in a special electrode, and is produced together with oxygen. There is a way. Nowadays, in any method, the purity of oxygen gas or water as a raw material is increased, and the material of a discharge electrode or a special electrode is improved, so that ozone gas with very few impurities can be obtained. The ozone concentration in the ozone gas obtained as described above is 10 to
At 20% by weight, the balance is oxygen. Ozone rapidly decomposes in both the gas phase and the liquid phase, so that it is not possible to obtain an ozone gas having a higher concentration.

Next, ozone water is produced by dissolving the ozone gas obtained as described above in water. As described above, when ozone water is used for cleaning a semiconductor wafer or the like, the higher the ozone concentration of the ozone water, the more effective the cleaning. Therefore, it is necessary to dissolve ozone in water as efficiently as possible. Devices for this include:
An ejector type as shown in FIGS. 4 to 6 has been proposed. Below, about this ejector type device,
A brief description will be given.

In FIG. 4, reference numeral 1 denotes an ozone generator, which supplies oxygen to the ozone generator 1 and generates ozone by passing the ozone generator 1 through a discharge tube in the ozone generator 1. Ozone produced by the ozone generator 1 is sent to an ejector 3 to be described later via a pipe 13.

The ejector 3 is configured as shown in FIG. That is, the inlet 30 and the outlet 3
An inner tube 32 is provided in a front portion 34 of an outer tube 39 having a suction port 35 and an expansion tube 37 in a rear portion 33. The tip of the inner cylinder 32 is located at the rear stage (lower stage in FIG. 5).
The nozzle portion 31 has a smaller diameter as going toward.
Pure water is fed from the feed port 30 of the ejector 3. The pure water is pressurized by a pressure feeding device (not shown), adjusted to an appropriate amount by a valve 12 (FIG. 4) and a flow meter 2 (FIG. 4), and enters the ejector 3. The fed pure water is blown out from the nozzle unit 31, and at this time, the pressure in the chamber 36 provided at the subsequent stage of the nozzle unit 31 is made negative. Thereby, the ozone gas is sucked from the suction port 35 connected to the ozone generator 1 and the pipe 13. Part of this ozone gas enters the pure water as fine bubbles in the chamber 36. Further, these bubbles and pure water are supplied to the expansion tube 3
7, and ozone in the bubbles is absorbed into the pure water.
Then, the paper is sent out from the delivery port 38. The remaining unabsorbed ozone and the oxygen generated by the change in ozone form a gas-liquid mixed phase, which is also the outlet 3
Emitted from 8.

The gas-liquid mixed phase sent out from the ejector 3 is sent to a storage tank 4 by a pipe 14, and the storage tank 4
Stay inside. In the storage tank 4, the bubbles in the gas-liquid mixed phase rise due to buoyancy or the like and accumulate on the liquid surface as gas. On the other hand, the ozone water is carried to a destination (not shown) from a pipe 16 having one end connected to the bottom of the storage tank 4. The above-mentioned target point (point of use) refers to a cleaning apparatus or the like that constitutes the above-described semiconductor manufacturing apparatus.

The gas collected on the liquid surface exits from the gas discharger 5 and is sent to the ozone decomposer 6. Then, by passing between the activated carbon particles filled in the ozone decomposer 6, the ozone gas undergoes a chemical reaction, is decomposed into oxygen and carbon dioxide, and is provided at an outlet provided at the upper part of the ozone decomposer 6. Emitted from 19.

The structure of the gas discharger 5 is as shown in FIG. That is, a spherical body 52 having a specific gravity smaller than at least ozone water is housed inside a bottomed cylindrical main body 51 made of stainless steel or the like while keeping a slight gap from the inner side surface of the main body 51. An inlet 56 is provided at a lower portion of the main body 51 (a lower portion in FIG. 6). Further, on the upper part of the main body 51 (the upper part in FIG. 6), there is provided a valve means 58 which is interlocked with the sphere 52 and the connecting rod 53. The valve means 58 includes a valve body 54
When the spherical body 52 is lifted by the buoyancy of the water flowing into the gas discharger 5, the valve body 54 comes into contact with the valve seat 55 and is sealed. In other words, it has a structure like a float valve as a whole. In FIG. 5, reference numeral 57 denotes an outlet.

With the above configuration, when all of the gas on the liquid level in the storage tank 4 is sent to the ozone decomposer 6 via the gas discharger 5, the ozone water in the storage tank 4 Then, the sphere 52 is pushed up into the main body 51 through the entrance 56 and pushed up. As a result, the valve element 54 contacts the valve seat 55 to close the valve means 58. As a result, the gas sent out from the storage tank 4 is no longer sent out through the gas discharger 5 and gathers at the upper portion of the main body 51.
Then, the water level in the gas ejector 5 is pushed down by the gas and descends, pushing down the sphere 52. As a result, the valve element 5
4 leaves the valve seat 55 and the valve means 58 is opened again.
Hereinafter, the above operation is repeated. Therefore, the storage tank 4
Can carry only ozone water to the point of use via a pipe 16 connected to the bottom. In FIG. 1, reference numeral 7 denotes an ozone water concentration meter, and reference numerals 17 and 18 denote an inlet pipe and an outlet pipe, respectively.

[0013]

If ozone water is produced by the above-described ozone water producing apparatus, cleaning with ozone water can be performed instead of the RAC cleaning. However, the above-described ozone water production apparatus has the following problems to be improved. That is, the ejector 3 and the gas discharger 5 are made of a metal material or a resin material due to structural restrictions. On the other hand, as described above, ozone is a substance having a strong oxidizing power. Therefore, when dissolved in water, even though a stainless steel or fluororesin-based material that is an oxidation-resistant material is used, a small amount of ozone is used. Oxidized by water and dissolved in pure water to become impurities. In the manufacture of semiconductors such as integrated circuits, the impurity concentration on the wafer surface after cleaning with a cleaning device is determined by the number of various metal atoms per unit surface area (1 cm ² ) (atm).
In the current generation of integrated circuits whose degree of integration is on the order of megabits, the number is required to be 10 ¹² (atm). If the degree of integration is in the order of gigabits due to the improvement of the degree of integration in the future, the above number will be 10 ¹⁰ (at
m) is required, and the next generation is 10 ⁹ (at
m) It is presumed that a table is required. To cope with such high integration, ozone water of higher and higher purity is required.

However, in the conventional technique, since the metal or the resin is used as described above, it is not possible to cope with further higher purification of ozone water. Therefore, in the field of semiconductor manufacturing and the like, ozone cleaning, which is the core of a cleaning method instead of RCA cleaning, has not yet been adopted in earnest because of the high content of impurities.

An ozone water producing apparatus according to the present invention has been devised in view of the above circumstances, and an object thereof is to provide an apparatus capable of producing high-purity ozone water. is there.

[0016]

In order to achieve the above object,
An ozone water producing apparatus according to the present invention, as described in claim 1, retains an ejector for injecting pure water and sucking ozone gas, and a gas-liquid mixed phase generated by suction of pure water and ozone gas from the ejector. A storage tank, a pipe connecting the storage tank and the ejector, a valve means for discharging a gas phase separated from the gas-liquid mixed phase in the storage tank, and a gas phase of the gas-liquid mixed phase. A delivery pipe for delivering ozone water obtained by discharging water to a destination,
It has. In particular, the ozone water producing apparatus according to the first aspect is characterized in that the gas-liquid mixed phase or the member that comes into contact with the ozone water is made of an ozone-resistant material. In addition, as the ozone-resistant material, specifically, at least one of quartz glass and hard glass can be used. Further, as the member that the gas-liquid mixed phase or ozone water contacts,
As described in claim 3, at least the ejector, the storage tank, the pipe, and the delivery pipe can be used.

Further, as described in claim 4, a liquid level detecting means for detecting the liquid level of the gas-liquid mixed phase or ozone water in the storage tank without contacting the gas-liquid mixed phase or ozone water. Control means for opening and closing the valve means in accordance with the detection value of the liquid level detection means, wherein the control means is configured to control the valve when the liquid level detected by the liquid level detection means is lower than a predetermined value. It is also possible to adopt a configuration in which the means is opened, the valve means is closed when the liquid level is higher than a predetermined value, and the liquid level is kept substantially constant. Specifically, as the liquid level detecting means, as described in claim 5,
An ultrasonic level gauge or an optical level gauge installed on the outer surface of the storage tank can be employed.

Since the apparatus for producing ozone water according to the present invention is configured as described above, it is possible to form a material such as an ejector, a storage tank, a pipe, a delivery pipe, etc., in contact with a gas or liquid containing ozone. However, it is almost completely prevented that impurities are mixed into ozone water generated by being oxidized by ozone. Furthermore, if the liquid level detecting means is provided in non-contact with ozone water or the like, the ozone water is prevented from being contaminated by the members constituting the liquid level detecting means, and can contribute to the production of ozone water of further purity.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the present invention will be described with reference to the drawings. 1 to 3
1 shows an embodiment of the present invention. The ozone water producing apparatus according to the present invention has a feature in that the purity of the produced ozone water is increased by devising a material of a member that comes into contact with a liquid or a gas containing ozone. Other configurations and operations are substantially the same as those of the above-described conventional ozone water producing apparatus. Therefore, the same parts as those of the conventional structure are denoted by the same reference numerals, and redundant description is omitted or simplified. The following description focuses on the characteristic portions of the above.

As shown in FIG. 2, an ejector 60 constituting the ozone water producing apparatus according to this embodiment has a cylindrical outer cylinder 6.
Outward flanges 69 are integrally formed at both ends (the left and right ends in FIG. 2) of each of the reference numerals 1. The material of the outward flange 69 may be resin or metal, but may be made of a material having a certain rigidity so as not to hinder the mounting of the ejector 60. Outer cylinder 61
Except for the outer flange 69 and the outer flange 69, all are made of quartz glass. In FIG. 2, reference numeral 62 denotes a nozzle, from which pure water can be press-fitted. Reference numeral 63 denotes a spacer, and an inner portion of the spacer 63 corresponds to the chamber 36 of the ejector 3 having the conventional structure described above. The spacer 63 has a cylindrical shape, and has a suction port 100 in a part of a side wall. Ozone gas is sucked from the suction port 100. The diffusers 64 and 65 are provided after the spacer 63 (right side in FIG. 2).
Is provided. In the case of the present embodiment, the diffuser 64,
Although 65 is divided into two parts for convenience in production, it may be provided integrally. At this portion, the ozone gas enters the pure water as fine bubbles to form a gas-liquid mixed phase, and the ozone is dissolved in the pure water. In FIG. 2, reference numeral 66 denotes an element for promoting gas-liquid separation and remixing, and for sufficiently dissolving ozone gas in pure water. This element 66
Has a plurality of circular holes 67 formed in a disk-shaped quartz piece.
Reference numeral 68 denotes an outlet spacer.

The apparatus for producing ozone water according to the present embodiment is provided with an ultrasonic level gauge 78 as shown in FIG.
The ultrasonic liquid level meter 78 is a liquid level detecting means described in the claims. The ultrasonic level gauge 78 includes a sensor head 79 and a microcomputer 80 as control means for controlling a detection signal from the sensor head 79.
(FIG. 1). The sensor head 79 oscillates ultrasonic waves and receives the reflected waves. Then, the microcomputer 80 calculates the difference between the energy levels. When the liquid is present in the storage tank 70 at a position higher than the sensor head 79 installation position, the level of the reflected wave with respect to the oscillating wave is high. Does not exist, the level of the reflected wave is lower than that of the oscillation wave. The ultrasonic level gauge 78 utilizes this property to detect the presence or absence of liquid in front of the sensor head 79. Therefore, the predetermined value described in the claims corresponds to the liquid level at the mounting position of the sensor head 79.

The ultrasonic level gauge 78 constructed as described above.
The ejector 60 configured as described above is arranged as shown in FIG. 1 together with the components of the ozone producing apparatus 1 and the like, similarly to the conventional apparatus described above. In particular, in the case of the structure of the present embodiment, at least the ejector 60, the storage tank 70, and the pipe 7, which are members that come into contact with the gas-liquid mixed phase or ozone water.
1 and the delivery pipe 73 are made of quartz glass, which is one of the materials having ozone resistance. As a liquid level detecting means for detecting the liquid level in the storage tank 70, an ultrasonic liquid level meter 7 which can be detected in a non-contact manner with a gas-liquid mixed phase or ozone water is used.
When the liquid level detected by the ultrasonic liquid level meter 78 is lower than the predetermined value, the microcomputer 80 opens the valve means 90 described below, and the liquid level is higher than the predetermined value. In some cases, the microcomputer 80 is connected to the valve means 9.
0 is closed to keep the liquid level almost constant.

In this embodiment, an electromagnetic on-off valve is employed as the valve means. This solenoid on-off valve can be opened and closed by a command signal sent via a cable 82 connected to the microcomputer 80. The upper end opening of the storage tank 70 is sealed by a sealing device having a lid device and an O-ring.

The operation at the time of producing ozone water using the ozone water production apparatus of this embodiment configured as described above is as follows. That is, the pure water is pumped into the ejector 60, the ozone gas 13 is sucked, and these are mixed. The pure water is press-fitted from the nozzle 62 and generates a negative pressure inside the spacer 63. On the other hand, the ozone gas is sucked from a suction port 100 provided in a part of the side wall of the spacer 63. The sucked ozone gas is converted into a gas-liquid mixed phase present as fine bubbles in pure water at the diffusers 64 and 65, and the ozone gas is dissolved in the pure water. Further, by passing the gas-liquid mixed phase through the element 66, the separation and re-mixing of the gas-liquid are repeated, and the ozone gas is sufficiently dissolved in the pure water. Then, it is discharged from the spacer 68.

The spacer 68 constituting the ejector 60
The gas-liquid mixed phase extruded from the quartz glass pipe 7
After passing through 1, the storage tank 70 is also made of quartz glass. The bubbles rise in the storage tank 70 due to buoyancy and the like, and separate on the liquid surface. A valve means 90 is provided at the end of the gas discharge pipe 77. When the liquid level of the storage tank 70 is above the sensor head 79, the valve means 90 is automatically closed by a command signal from the microcomputer 80. I do. On the other hand, when the liquid level falls below the sensor head 79, the liquid is automatically opened by a command signal from the microcomputer 80. Therefore, when the gas is collected at the upper part of the storage tank 70 and stays there, the liquid level in the storage tank 70 is pushed by this gas and falls. As a result, the liquid level in the storage tank 70 drops below the sensor head 79 and the valve means 90 is opened, so that the gas is released by being pressed by the liquid pressure and discharged via the ozone decomposer 6. As a result, the liquid level in the storage tank 70 rises again. In this way, the liquid level in the storage tank 70 is kept substantially constant.

Since the ultrasonic level gauge 78 is provided on the outer wall of the storage tank 70, the liquid level can be measured without directly touching the gas-liquid mixed phase in the storage tank 70. Further, as in the conventional gas discharger 5 (FIG. 6), the ozone water is supplied to the main body 51 or the sphere 52 made of stainless steel.
And the valve means 78 does not touch the ozone water. According to the present embodiment, in the steps after the mixing point of ozone and pure water, there is absolutely no contact portion other than quartz glass, and due to the excellent ozone resistance of quartz glass, extremely high-purity ozone water is produced. be able to.

The following test was conducted in order to examine the effects of the present embodiment configured as described above. In other words, the impurities (Na, A) contained in the ozone water produced by the conventional apparatus described above and the ozone water production apparatus according to the embodiment described above.
1, Cr, Fe, Ni, Cu, Zn) were examined and compared. 5mg each of ozone water used as a sample
/ L or 5 ppm, and 10 mg / l or 10
With respect to ppm, a treatment time of 3 minutes and a treatment time of 30 minutes were prepared. The test results are shown in Table 1 below.

[0028]

[Table 1]

As is clear from the description in this table, the impurity concentration on the wafer surface after cleaning satisfies the level required for next-generation integrated circuits. Therefore,
By producing ozone water using the ozone water production apparatus according to the present embodiment, in the cleaning apparatus attached to the semiconductor production apparatus, cleaning with ozone water can be realized instead of the RCA cleaning.

In the above-described embodiment, the material of the contact portion with the ozone water such as the ejector 60 is quartz glass, but hard glass may be used. Since the hard glass has almost the same ozone resistance as quartz glass,
Hard glass can be adopted as the material of the contact portion. Also, a configuration in which quartz glass and hard glass are mixed may be used. Further, the ultrasonic liquid level meter 78 is used as the liquid level detecting means of the storage tank 70, but an optical liquid level meter may be used instead. Also, the valve means 90 is not limited to this embodiment, and various conventionally known valve devices can be employed. The point is that the material in contact with the ozone water and the gas-liquid mixed phase may be made of the above-mentioned quartz glass, hard glass or the like having ozone resistance.

[0031]

The apparatus for producing ozone water according to the present invention is constructed and operates as described above, so that extremely high-purity ozone water can be produced. As a result, cleaning used in the field of semiconductor manufacturing of integrated circuits and the like can be performed using ozone water, which contributes to a reduction in labor and cost of waste liquid treatment and prevention of environmental destruction.

[Brief description of the drawings]

FIG. 1 is a schematic circuit diagram showing a first embodiment of the present invention.

FIG. 2 is a vertical sectional side view showing the ejector.

FIG. 3 is a main part side view showing the installation state and the liquid level detection state of the liquid level meter.

FIG. 4 is a view similar to FIG. 1, showing a conventional configuration.

FIG. 5 is a vertical sectional side view showing a conventional ejector.

FIG. 6 is a vertical sectional side view showing a conventional gas discharger.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ozone generator 3 Ejector 4 Storage tank 5 Gas discharger 6 Ozone decomposer 7 Ozone water concentration meter 13, 14, 15, 16 Pipe 17 Inlet pipe 18 Outlet pipe 19 Discharge pipe 30 Feed pipe 31 Nozzle part 32 Inner cylinder 33 Subsequent stage Part 34 front part 35 suction port 36 chamber 37 expansion pipe 38 delivery pipe 39 outer cylinder 51 main body 52 sphere 53 connecting rod 54 valve body 55 valve seat 56 inlet 57 outlet 58 valve means 60 ejector 61 outer cylinder 62 nozzle 63 spacer 64, 65 Diffuser 66 Element 67 Circular hole 68 Spacer 69 Outward flange 70 Storage tank 71 Piping 73 Outgoing pipe 77 Gas exhaust pipe 78 Ultrasonic level gauge 79 Sensor head 80 Microcomputer 81, 82 Cable 90 Valve means 100 Suction port

Claims (5)

[Claims] 1. An ejector for injecting pure water and sucking ozone gas, a storage tank for retaining a gas-liquid mixed phase generated by suction of pure water and ozone gas from the ejector, and connecting the storage tank to the ejector. Piping, a valve means for discharging a gas phase separated from the gas-liquid mixed phase in the storage tank, and an ozone water obtained by discharging the gas phase of the gas-liquid mixed phase to a destination point. An ozone water producing apparatus, comprising: an ozone water producing apparatus, wherein the member in contact with the gas-liquid mixed phase or the ozone water is produced from an ozone-resistant material. 2. The ozone-resistant material is at least one of quartz glass and hard glass,
The ozone water production device according to claim 1. 3. The member in contact with the gas-liquid mixed phase or ozone water is at least the ejector, the storage tank, the pipe, and the delivery pipe.
An ozone water production apparatus according to claim 2. 4. A liquid level detecting means for detecting a liquid level of the gas-liquid mixed phase or ozone water in the storage tank without contacting the gas-liquid mixed phase or ozone water, and a detection value of the liquid level detecting means. Control means for opening and closing the valve means in response to the control, wherein the control means opens the valve means when the liquid level detected by the liquid level detection means is lower than a predetermined value, and the liquid level is 4. The ozone water producing apparatus according to claim 1, wherein the valve means is closed when the pressure is higher than a predetermined value, and the liquid level is kept substantially constant. 5. The ozone water producing apparatus according to claim 4, wherein said liquid level detecting means is an ultrasonic liquid level meter or an optical liquid level meter installed on an outer surface of said storage tank.