JP3538470B2 - Downward rectification type immersion cleaning device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a descending rectifying type immersion cleaning apparatus capable of removing suspended particles on the liquid surface of a cleaning tank and controlling the liquid level with respect to fluctuations in the flow rate of a supply liquid.

[0002]

2. Description of the Related Art Conventionally, semiconductor wafers and glass substrates for liquid crystals have been mainly cleaned by immersion chemical cleaning in which an object to be cleaned is immersed in a cleaning liquid. Cleaning is a step of removing dirt attached to the object to be cleaned by processing in a cleaning chemical solution,
The method includes a step of rinsing the cleaning liquid remaining on the object to be cleaned after treatment with pure water and a step of drying the object to be cleaned after rinsing.

[0003] In the case of immersion cleaning using a cleaning chemical solution, contaminant particles released from an object to be cleaned are dispersed in the cleaning liquid, and as the number of objects to be cleaned increases, the concentration of the contaminant particles accumulated in the cleaning tank increases, so that cleaning is performed. There is a problem that re-contamination by the above-mentioned particles occurs on the cleaned object to be cleaned, and a part of the cleaning liquid in the cleaning tank is continuously withdrawn and passed through a filter to remove the dispersed contaminating particles, and then the original cleaning liquid is returned. It is indispensable to carry out so-called circulation filtration by returning to the tank. As described above, an overflow type cleaning tank has been conventionally used as a method of extracting the cleaning liquid from the cleaning tank and returning the cleaning liquid to the cleaning tank again.

On the other hand, in the case of pure water rinsing for rinsing, fresh pure water is continuously supplied from the lower part of the rinsing tank,
Pure water overflows beyond the peripheral edge at the top of the rinsing tank and overflows outside the tank. There is a method of continuing until the quality of the water matches.

[0005] In both the case of circulating filtration of the cleaning liquid and the case of rinsing with pure water, the higher the ability to completely and completely remove the chemical components and dirt brought into the cleaning tank or the rinsing tank in a short time, that is, the higher the discharge and replacement efficiency. In addition, high washing quality of immersion washing can be economically obtained in a short time. However, the conventional immersion cleaning tank supplies a cleaning liquid or pure water from the bottom side of the tank,
The overflow method that overflows from the upper end of the tank is mainly used.

FIG. 6A shows a visualization of a water flow in a cleaning tank in which overflow cleaning is performed in order to clean a large number of objects to be cleaned such as wafers and substrates arranged at relatively small intervals. The cleaning liquid supplied from the bottom of the cleaning tank 11 as shown in FIG. 3B and having passed through the scoop-shaped cleaning object support plate 12 shown in FIG. It flows mainly through a wide area between the tank and the inner wall of the tank and rises. Then, although the liquid overflows from the upper edge of the tank, a part of the upward flow moves toward the center of the tank along the liquid surface, and further slowly passes through a narrow gap formed by a wafer, a substrate, and the like from above the object 13 to be cleaned. It changes to descending flow. This gentle downward flow is attracted to and mixed with the upward flow of the supply liquid below the object to be cleaned. That is, a circulating flow is generated in the cleaning tank from the tank wall side toward the center of the tank, and this circulating flow is important in the following two points.

The first problem is that, when batch processing is performed on an object to be cleaned such as a wafer or a substrate, the flow of the cleaning liquid on the surface of the object to be cleaned becomes extremely slow as compared with the flow rate of the supply liquid. The function of removing contaminants from the surface of the cleaning object and the function of removing the contaminated substances from the vicinity of the object to be cleaned are not sufficiently exhibited, and most of the supplied cleaning liquid flows out without contributing to the cleaning operation. Second, the contaminants detached from the object to be cleaned stay in the circulation flow in the cleaning tank for a long time. Therefore, a clean object to be cleaned after cleaning is again contaminated, and it takes an extremely long time until it is completely cleaned.

As a countermeasure against the above problem, FIG.
As shown in (b), the idea is to shield the other support plate except for the portion directly below the object to be cleaned, so that the cleaning liquid injected from the bottom of the tank directly rises between the objects to be cleaned. There is. When the flow is visualized and examined in the above case, the upward flow that reaches the liquid level through the gap between the objects to be cleaned becomes a horizontal flow toward the tank wall and overflows from the upper edge of the cleaning tank. After a considerable portion of the tank collides with the tank wall, it forms a downward flow along the tank wall, hits the support plate in the cleaning tank, and is attracted to the upward flow toward the center to mix. That is, a circulating flow opposite to the circulating flow is generated toward the tank wall. Although the first problem described above is improved, the second problem is not solved, and a long cleaning process is required to obtain sufficient cleaning quality.

As a solution to the drawbacks of the overflow method, the contaminated cleaning liquid that has passed through the object to be cleaned is forcibly discharged from the bottom of the cleaning tank through a perforated plate provided with pores, and the cleaning liquid corresponding to the discharge flow rate is removed. We have applied for a new washing tank using a method in which the ink is uniformly raised and supplied along the inner wall of the washing tank (Japanese Patent Application No. 5-260505).

FIG. 8 shows the condition when the object to be cleaned is cleaned in the cleaning tank and the flow of the cleaning solution is visualized and observed. Since the cleaning liquid is sucked downward by the pump through the perforated plate 14 under the object 13 to be cleaned, the suction flow rates of the plurality of fine pores appropriately dispersed and arranged on the perforated plate are substantially uniform. Therefore, at the cleaning object installation part of the cleaning tank,
A downward flow adjusted to a uniform flow velocity is formed. Therefore, it is difficult for the drift to selectively flow in the large gap between the periphery of the object to be cleaned and the tank wall, and the cleaning liquid flows well also in the narrow gap between the wafer and the substrate to be cleaned. , The flow velocity is made uniform.

There are various methods for supplying the cleaning liquid to the object to be cleaned. However, in order to rectify the downward flow satisfactorily, it is important to supply the cleaning liquid to the object to be cleaned. On the other hand, the best condition is that the flow rate of the cleaning liquid flowing from the surroundings is uniform. For this reason, a method is adopted in which the cleaning tank has a double tank structure including an outer tank and an inner tank, and a new cleaning liquid is supplied as an upward flow from below using a gap between the outer tank wall and the inner tank wall. In this case, it is desirable to provide four cleaning liquid injection ports so as to be symmetrical in the front-rear and left-right directions, and it is necessary to provide at least two injection ports at symmetric positions. The upward flow of the injection cleaning liquid cannot prevent the distribution of the flow velocity around the injection port from occurring. As a method for mitigating this flow velocity distribution as much as possible, for example, providing an obstacle to disperse the flow near the injection port, or as another method, a perforated plate for rectification in the wall gap between the outer tank and the inner tank It is to provide.

In such a cleaning tank, chemicals and contaminants brought into the tank by the object to be cleaned are separated from the surface of the object to be cleaned by rapid downflow rectification, quickly transferred, and discharged from the bottom of the tank. Since the object to be cleaned is placed in the downward rectification generated in the tank, there is no stagnation of released contaminants, and the cleaning liquid is replaced in the cleaning tank in a short time to be cleaned. That is, high-quality cleaning can be completed in a shorter time than the overflow-type cleaning tank, which is economically advantageous.

Using an overflow tank and a descending rectification tank having the same tank volume, rinsing with pure water at the same flow rate, that is, pure rinsing was performed. FIG. 9A shows the replacement and discharge characteristics of the ions carried into the tank at this time. The conductivity of the pure water flowing out of each tank is plotted on a logarithmic scale on the vertical axis, and the elapsed time of rinsing is based on the time when the wafer cassette immersed in the saline solution is pulled up and placed in the rinsing tank. The horizontal axis is on a minute scale. However, the conductivity value at each time is shown as a ratio with the highest value immediately after the cassette is placed in the tank. As is clear from FIG. 9 (a), the solid line indicating the case of the descending rectification tank has a faster decrease of the ion concentration in the tank, and the rinsing time until the ion concentration decreases to the same concentration is the case of the overflow tank indicated by the broken line. About 1/2 of Because the pure water flow rate is the same,
By using the descending rectification tank, the amount of expensive pure water used can be halved, and the running cost can be significantly reduced.

Also, as shown in FIG. 9 (b), the descending rectification tank has a value about twice as large as that of the overflow tank with respect to the reduction rate of the particle concentration in the washing tank performing the circulation filtration. . In other words, the contaminated fine particles brought into the tank by the object to be cleaned are filtered and removed in about half the time of the overflow tank in the descending rectification tank assuming that they are circulated and filtered under the same conditions, and the contaminant particles to the object to be cleaned are removed. It can be expected that the chance of re-contamination will be significantly reduced and a high-purity cleaning surface will be obtained. By using the descending rectifying tank as described above, a circulating flow in the tank is not generated, and a considerable flow rate is applied to a narrow gap between the objects to be cleaned, such as when cleaning a wafer or a glass substrate, and the pure water is uniformly distributed. Water can now flow,
High-quality washing can be performed quickly and economically as compared with the overflow tank.

[0015]

However, there are the following problems when the cleaning liquid or the rinsing is actually performed using the cleaning tank of the descending rectification type. That is, if the supply flow rate and the discharge flow rate do not match, the liquid level fluctuates. If there are contaminant particles floating on the liquid surface, they will stay on the liquid surface as it is, so when the object to be cleaned is taken out of the tank after cleaning, the above-mentioned floating particles adhere to the object to be cleaned and cause recontamination. become.

When the liquid level changes and the liquid level approaches the upper edge of the inner tank, the flow of the cleaning liquid into the inner tank is disturbed, the rectification of the cleaning liquid in the tank is lost, and the efficiency of replacement of the cleaning liquid is reduced. Decreases.

An object of the present invention is to solve these problems and to provide a descending rectifying type immersion cleaning apparatus for performing high quality cleaning in a short time with a small flow rate of a cleaning liquid or pure water.

[0018]

The object of the present invention is to provide a double tank having an inner tank and an outer tank formed in a rectangular shape, and to inject a cleaning liquid from a lower portion of a gap provided between the inner tank and the outer tank. In a descending rectifying type immersion cleaning apparatus, a cleaning liquid is poured into the object to be cleaned from the upper edge of the inner tank, and the contaminated cleaning liquid containing contaminant fine particles released from the object to be cleaned is discharged from the bottom of the inner tank through the perforated plate. An overflow portion of the cleaning liquid is provided on the upper edge of one side of the outer tank,
The cleaning liquid level control means is installed in the inner wall of the outer tank other than the above-mentioned overflow portion, and the flow rates are different from each other.
This is achieved by providing two flow paths at the cleaning liquid inlet and providing means for controlling the flow rate. Further, a perforated plate is provided above the gap between the inner tank and the outer tank, and the cleaning liquid permeated through the perforated plate is poured from the upper edge of the inner tank to the object to be cleaned. Further, the liquid level is controlled by a level sensor provided on the inner wall of the tank. That is, it has a function of eliminating suspended particulates by providing the liquid level control and the overflow portion, and reducing the cleaning liquid in a state where cleaning is not performed by the flow rate control means.

[0019]

A double tank is constituted by an inner tank formed in a square shape and an outer tank provided so as to surround the inner tank, and the upper edge of one of the four wall surfaces of the outer tank is made higher than the upper edge of the other three wall surfaces. An overflow portion of the cleaning liquid is formed to be low, and an overflow tank and a drain pipe for receiving the overflowing cleaning liquid are provided on the outer wall of the overflow portion. A cleaning liquid inlet is provided at the bottom of the gap formed between the inner wall of the outer tank and the outer wall of the inner tank, and a perforated plate for rectifying the injected cleaning liquid is provided around the outer periphery of the inner tank above the gap. ing. The inner tank whose upper edge is set at a position lower than the overflow portion is provided with a perforated plate at a position where the object to be cleaned is sufficiently immersed in the cleaning liquid to serve as a mounting table for the object to be cleaned, and an inner tank below the mounting table. A discharge port is provided on the bottom surface, and the contaminated cleaning liquid that has passed through the perforated plate is sucked and discharged by a pump provided outside the tank. The shape of the overflow portion and the edge of the upper edge of the inner tank where the cleaning liquid or pure water overflows is formed in a sawtooth shape so that the overflow can be uniformly performed.

The above configuration is the basic configuration of the descending rectification type immersion cleaning tank, and a perforated plate is provided in the gap between the inner tank and the outer tank in order to inject the cleaning liquid into the object to be cleaned at a flow rate as uniform as possible. Although the flushing of the injection cleaning liquid is performed, in order to further improve the degree of rectification, at least two or more symmetrical positions are provided on the bottom of the outer tank around the inner tank in order to further improve the degree of rectification.

A level sensor is provided at a position above the upper edge of the inner tank so that the average liquid level is maintained within a certain range. In the cleaning apparatus of the present invention, the liquid level is previously set above the upper edge of the inner tank, but if the flow rate of the cleaning liquid to be injected matches the discharge flow rate of the pump, the initially set liquid level is maintained as it is. However, in practice, it is unavoidable that the flow rate slightly fluctuates. Therefore, if the flow rate difference between the injection flow rate and the discharge flow rate is plus, the liquid level rises, and if it is minus, it falls. Even if the liquid level rises above the level above the set liquid level and reaches the edge of the overflow portion, it naturally overflows and is drained, so there is not much problem. , The flow of the cleaning liquid flowing from the upper edge to the object to be cleaned is remarkably disturbed. As a result, the rectification in the inner tank is lost and the efficiency of replacing the cleaning liquid is reduced. Therefore, in order to maintain the performance of the cleaning device stably, it is important to control the liquid level within a relatively narrow range. For this purpose, level sensors are installed at the upper and lower levels to reduce the liquid level. Try to maintain.

At the inlet of the cleaning liquid, a flow path A for a flow rate slightly smaller than the suction flow rate of the discharge port and a flow path B for a flow rate slightly larger than the suction flow rate are provided.
A flow control needle valve, a flow meter and a filter will be installed so that the flow rate can be selected independently. When the operation is performed in the flow path A, the liquid level is lowered to reach a low value level sensor, the valve of the flow path B is opened by the sensor, the liquid level is raised, and the liquid level sensor in the high position is reached, The valve closes and the liquid level drops again.

Furthermore, if floating dust drops on the surface of the cleaning liquid and stays on the liquid surface for some reason, it is inevitable that the floating dust adheres when the object to be cleaned is lifted from the bath. In such a case, when all valves other than the cleaning liquid inlet valve are closed, the liquid level rises, and since the discharge port is also closed, the liquid level exceeds the upper liquid level sensor and flows out of the overflow portion. The floating dust is discharged together with the overflowing cleaning liquid. When the dust is discharged, open the closed valve to return to normal operation. Furthermore, when only the flow path A having a small flow rate is opened during the pure water rinsing and the suction pump connected to the discharge port is stopped, the pure water is discharged by gravity and the flow rate of the pure water can be reduced. When performing circulation filtration, the destination of the suction pump is connected to the above-mentioned flow path instead of the drain.
By these actions, high quality cleaning can be performed with a small flow rate of the cleaning liquid. Although the above description has been made mainly for the cleaning tank and the cleaning liquid, the same applies to pure water in the rinsing tank.

[0024]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing an embodiment of a descending rectification type immersion cleaning apparatus according to the present invention. FIG. 1 is a view showing a cross section of a cleaning tank of a descending rectification type immersion cleaning apparatus according to the present invention, FIG. 2 is a perspective view showing an appearance of the cleaning tank, FIG. 3 is a top view of the cleaning tank, and FIG. FIG. 5 is a diagram showing a piping example of the immersion cleaning device.

As shown in FIG. 1, the cleaning tank for the downward rectification type immersion cleaning apparatus of the present invention is a double tank in which an inner tank 1 and an outer tank 2 surrounding the inner tank 1 are formed in a rectangular shape. The upper edge of one of the short sides is lower than the height of the other wall of the outer tub, and the overflow portion 3
An overflow tank 4 and a drain pipe 5 for receiving the cleaning liquid overflowing to the outside are provided. A cleaning liquid injection port 6 is provided at the bottom of the gap formed between the inner tank 1 and the outer tank 2, and a perforated plate 7 having a plurality of holes is provided at the top of the gap.
Is provided along the outer wall of the inner tank 1 for rectifying the injected cleaning liquid. The upper edge of the inner tank 1 is filled with the overflow 3
A lower position is set, and an installation table 8 for the object to be cleaned is provided at a position where the object to be cleaned is sufficiently immersed in the cleaning liquid in the inner tank. It is constituted by a plate, and passes the contaminated cleaning liquid after cleaning the object to be cleaned, rectifies the flow of the cleaning liquid in the inner tank 1, and discharges the same through a discharge port 9 provided at the bottom of the inner tank 1 directly below the installation table 8. The contaminated cleaning liquid is sucked and discharged by the function of a pump provided outside the tank. In the above configuration, the cleaning liquid injected from the injection port 6 is supplied to the inner tank 1.
By raising the gap formed between the inner tank 1 and the outer tank 2 and passing the same through the perforated plate 7 provided above the gap, the rectified cleaning solution is washed from the upper edge of the inner tank 1 at a uniform flow rate in the inner tank. In order to make the flow rate of the cleaning liquid uniform and to further stabilize the flow, it is necessary to arrange the cleaning liquid inlet 6 at the bottom of the gap as symmetrically as possible. A symmetric arrangement as shown in FIG. 3 is performed.

When the flow rate of the cleaning liquid injected from the injection port 6 of the cleaning liquid is equal to the flow rate of the contaminated cleaning liquid discharged from the discharge port 9, the level of the cleaning liquid in the cleaning tank is kept constant. When the balance between the two flow rates is lost, the amount of the cleaning liquid increases or decreases. That is, if the flow rate difference between the injection flow rate and the discharge flow rate becomes positive, the liquid level rises, and if it becomes negative, the liquid level drops. Actually, it is unavoidable that the flow rate slightly fluctuates. If the flow rate continues to rise, it reaches the upper edge of the overflow portion 3 and overflows and is discharged. Descends and approaches the upper edge of the inner tank 1, the rectification of the cleaning liquid injected into the object to be cleaned over the upper edge is disturbed, and the efficiency of replacement of the cleaning liquid decreases.
Therefore, the fluctuation of the liquid level of the cleaning liquid in the tank must be controlled within a relatively narrow range, but the allowable fluctuation range is about ± 10 mm with respect to a predetermined average liquid level as shown in FIG. Desirably. Therefore, the liquid level sensors 10 (LH and L
L) is installed to keep the fluctuation of the cleaning liquid level within a certain range. An example of the relationship between the height of the inner tank 1 and the outer tank 2, the height of the overflow portion 3, and the average liquid level is as shown in FIG.

The four cleaning liquid inlets 6 provided at the bottom of the gap between the inner tank 1 and the outer tank 2 of the main cleaning tank are opened and closed via valves V ₁ , V ₂ , V ₃ and V _{4 respectively} . The cleaning liquid flow path is connected to the discharge port 9 as shown in FIG.
From the flow rate A set to a flow rate slightly smaller than the suction flow rate Q1 / min, for example, the flow rate (Q-2) reduced to about 2 l / min, l / min, and the flow path B set to a flow rate of about 3 l / min. Each flow path is composed of opening and closing valves V ₆ and V ₇ , flow rate adjusting needle valves V ₈ and V ₉ , flow meters M ₁ and M _2, and filters F ₁ and F ₂ , respectively. By switching, each flow rate can be selected independently. When the operation is performed by the flow path A, the supply flow rate is smaller than the suction flow rate, so that the level of the cleaning liquid decreases,
Eventually, it reaches the liquid level sensor LL. Valve V ₇ of the flow path B by the operation of the sensor LL opens, the flow rate (Q-2 + 3) l
/ Min, that is, about 1 l / min, which is larger than the suction flow rate, and the liquid level rises. Rise to continue the cleaning liquid surface will soon reach a liquid level sensor LH, but can be lowered cleaning liquid surface by closing a valve V ₇ of the flow path B by the level sensor LH. With such a control method,
The cleaning liquid level in the cleaning tank is
The cleaning process can be performed by raising and lowering in a range of 10 mm. The flow rate setting values of the flow paths A and B are not fixed to the above-described values, but need to be appropriately set based on the flow rate fluctuation value on the cleaning liquid injection side.

To perform precision cleaning, a cleaning device is installed in a clean booth or the like in order to avoid contamination such as floating dust. However, in the unlikely event that airborne dust settles on the cleaning liquid level, it will remain in the cleaning liquid level, causing the floating dust to adhere when the object to be cleaned is lifted from the cleaning tank, It will be polluted again. When floating dust is present on the cleaning liquid surface, the valve V in FIG.
Inlet valves V ₂ , V ₃ , V ₄ other than ₁ and outlet valve V ₅
When closing, the valve of the cleaning liquid surface rises the liquid level sensor LH acts passage B is closed, subsequently the washing liquid surface rises because the outlet valve V ₅ is closed, reaches the overflow portion 3 Out of the drain pipe 5. At this time, a horizontal flow on the surface is formed from one side of the cleaning tank toward the overflow section 3,
Dust floating on the surface is discharged in a relatively short time together with the flow. When the floating dust is removed, the closed valves V ₂ , V ₃ , V ₄ and V ₅ are opened, and the discharge port 9 by the pump is opened.
When the suction from the nozzle is restarted, the cleaning liquid level decreases because the cleaning liquid injection flow rate is smaller than the suction flow rate. In order to return to the fast predetermined level cleaning liquid surface is temporarily inlet valve V ₁ ~V ₄ may be closed.

Further, when the cleaning is temporarily interrupted, the flow rate of the pure water rinse tank is not reduced, and the flow rate of the pure water is reduced.
Open only valve V _1, stops a pump connected to the discharge port 9, flows out by gravity flow by opening the valve V _10. For flow rate of the natural flow is adjusted to balance the flow rate of the flow path B, and after the valve V ₁₀ is provided a needle valve V _11.

Although the above description has been made mainly of the cleaning liquid, the same applies to the case where pure water is used as the rinsing tank. Further, the valve switching operation such as water level adjustment, elimination of floating dust, and water saving by switching to a small flow rate can be easily automated by sequence control using an automatic valve.

[0031]

As described above, the descending rectification type immersion washing apparatus according to the present invention comprises a double tank having an inner tank and an outer tank formed in a rectangular shape, and a gap provided between the inner tank and the outer tank. The cleaning liquid is poured from the lower part of the inner tank, the cleaning liquid is poured into the object to be cleaned from the upper edge of the inner tank, and the contaminated cleaning liquid containing the contaminant fine particles released from the object to be cleaned is discharged from the bottom of the inner tank through the porous plate. In the rectifying type immersion cleaning apparatus, an overflow portion of the cleaning liquid is provided on the upper edge of one side surface of the outer tank, and a liquid level control means of the cleaning liquid is installed in the inner wall of the outer tank except for the provision of the overflow section. By providing two different flow paths at the cleaning liquid inlet and providing a means for controlling the flow rate, precise cleaning with high cleaning degree can be performed in a short time with a small flow rate of the cleaning liquid or pure water. A downward rectification type immersion cleaning device is obtained.

[Brief description of the drawings]

FIG. 1 is a view showing a cross section of a cleaning tank of a descending rectification type immersion cleaning apparatus according to the present invention.

FIG. 2 is a perspective view showing an appearance of the cleaning tank.

FIG. 3 is a top view of the cleaning tank.

FIG. 4 is an explanatory diagram for liquid level control.

FIG. 5 is a view showing an example of piping of the descending rectification type immersion cleaning apparatus.

FIG. 6 is a diagram showing a flow of a cleaning liquid in a conventional overflow type cleaning tank.

FIG. 7 is a view showing a flow of a cleaning liquid in another example of the conventional cleaning tank.

FIG. 8 is a view showing a flow of a cleaning liquid in a descending rectifying type cleaning tank.

9A and 9B are diagrams showing a comparison of cleaning efficiency between an overflow type cleaning tank and a descending rectification type cleaning tank, wherein FIG. 9A shows a case of pure water rinsing, and FIG. 9B shows a case of circulation cleaning.

[Explanation of symbols]

1 inner tank 2 Outer tank 3 Overflow section 6 Inlet 7, 8 perforated plate 9 outlet 10 Level sensor

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-60-113433 (JP, A) JP-A-60-78680 (JP, A) JP-A-6-349804 (JP, A) JP-A-5-349 166791 (JP, A) JP-A-5-166787 (JP, A) JP-A-7-37850 (JP, A) JP-A-1-154463 (JP, U) JP-A-63-130183 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) B08B 3/10 H01L 21/304

Claims (3)

(57) [Claims] A cleaning liquid is injected from a lower part of a gap provided between the inner tank and the outer tank, and a washing liquid is injected from an upper edge of the inner tank. In a descending rectification type immersion cleaning apparatus in which a cleaning liquid is poured into an object to be cleaned and a contaminated cleaning liquid containing contaminant fine particles released from the object to be cleaned is discharged from the bottom of the inner tank through a perforated plate, Providing an overflow portion of the cleaning liquid at the edge, and installing a liquid level control means of the cleaning liquid in the inner wall of the outer tank other than providing the overflow portion,
A downflow rectification type immersion cleaning apparatus, characterized in that two flow paths having different flow rates are provided at a cleaning liquid inlet, and a means for controlling the flow rate is provided. 2. A gap provided between the inner tank and the outer tank is provided with a perforated plate at an upper portion thereof, and a cleaning liquid permeating the perforated plate is poured into an object to be cleaned from an upper edge of the inner tank. Claim 1
The descending rectification type immersion cleaning device as described. 3. The descending rectification type immersion cleaning apparatus according to claim 1, wherein the liquid level in the cleaning tank is controlled by a level sensor installed in the cleaning tank.