JP3386892B2 - Wash tank - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleaning tank for cleaning a wafer or the like when manufacturing a semiconductor device.

[0002]

2. Description of the Related Art An overflow tank is usually used as a cleaning tank used for cleaning wafers in the manufacture of semiconductor devices, and the cleaning solution injected from the cleaning solution injection port provided at the bottom of the cleaning tank is used for cleaning the contents on the holding shelf or Rise around the wash and flow,
The free surface of the cleaning liquid is overflowed into a groove provided on the outer periphery of the upper end of the cleaning tank and discharged from the discharge port to the outside of the tank. The above-mentioned washed product is generally a large number of wafers placed side by side in a cassette made of synthetic resin, and the cassette is locked and conveyed by a suspending tool of an automatic conveyance device, and immersed in the cleaning liquid just above the cleaning tank. Also, the contaminated cleaning liquid discharged from the discharge port is
After passing through the filter and being cleaned outside the cleaning tank,
It is circulated and supplied again to the cleaning tank. In the above conventional technology, the inflowing cleaning liquid spreads and rises in the cleaning tank,
The flow velocity is slower than that of the cleaning liquid that has a large resistance when passing through the cleaning product and rises outside the cleaning product, and it is difficult to obtain a sufficient cleaning effect, and some of the contaminated cleaning liquid that cannot overflow overflows along the inner wall of the cleaning tank. Since it descends and causes reflux in the cleaning tank, some of the fine particles released from the cleaning product will stay, and when cleaning is repeated, contaminant particles in the cleaning liquid gradually accumulate and the cleaning effect remarkably decreases. In order to solve these problems, the inventors of the present invention, as shown in FIG.
Cylindrical enclosure 1 with a gap and height that can carry in and out
6 is fixed to the bottom of the cleaning tank 15, and a support shelf 7 for the cleaning product 5 provided with a predetermined number of predetermined pores is installed at a position in the middle of the surrounding wall where the cleaning product 5 installed in the surrounding wall 16 is sufficiently immersed. , A cleaning tank having an outlet 8 for sucking and discharging the cleaning liquid 4 injected from the inlet 3 on the outer side of the lower wall of the cleaning tank is provided at the bottom of the cleaning tank below the support shelf 7 (Japanese Patent Application No. 5-260506).
issue).

[0003]

Although the problems of the overflow type cleaning tank are greatly improved by the above proposal, the improved cleaning tank flows the cleaning liquid into the relatively narrow wall to clean the object to be cleaned. On the other hand, a large amount of cleaning liquid is expected to flow smoothly in order to carry out effective cleaning in a short time, and the cleaning tank itself can be easily cleaned, and contaminated fine particles are always removed from the cleaning tank. There was a need for a cleaning tank that can be easily removed and is easy to maintain.

An object of the present invention is to provide a cleaning tank which can be efficiently cleaned in a short time and which can be easily maintained and managed.

[0005]

[Means for Solving the Problems] The above-mentioned object is to use a cleaning tank composed of a double tank including an inner tank and an outer tank, and to provide a bottom surface on the outer peripheral upper part of the inner tank so as to substantially close a gap between the inner tank and the outer tank. In addition to providing the perforated plates in parallel, the inner tank provided with the perforated plate on which the above-mentioned object to be cleaned is mounted as a support base is positioned at a position within the inner tank where the object to be cleaned can be sufficiently immersed in the cleaning liquid. Is sufficiently lower than the upper edge of the outer tub and can be removably installed inside the outer tub while maintaining a substantially equal gap around the outer tub. This is achieved by connecting the discharge port of the cleaning liquid, which rises the gap and pours from the upper edge of the inner tank to the object to be cleaned, to the discharge pipe outside the tank via the connecting means.

Further, the discharge port provided in the inner tank is connected to a discharge pipe provided in the outer tank through a pole joint, or the discharge port provided in the inner tank is O-ring sealed. It can be achieved by connecting to the discharge pipe through the joint of the.

[0007]

The cleaning tank according to the present invention is a cleaning tank having a double tank structure composed of an inner tank and an outer tank, which are substantially equidistant from the inner wall of the outer tank, and the upper edge of the inner tank is above the outer tank. At the upper part of the outer periphery of the inner tank that can be detachably installed so that it is sufficiently lower than the edge, there is a perforated plate that is parallel to the bottom so as to close the gap with the outer tank. A support base of a perforated plate that supports the object to be cleaned is provided at a position in the inner tank where it can be dipped. The cleaning liquid injected from the center of the bottom of the outer tank is conveyed to the upper edge of the inner tank at a substantially uniform flow rate, and a large amount of the cleaning liquid is evenly poured onto the object to be cleaned in the inner tank, resulting in contamination released from the object to be cleaned. The contaminated cleaning liquid containing fine particles is discharged from the discharge port provided at the bottom of the inner tank, but the discharge port at the bottom of the inner tank is outside the outer tank so that the inner tank can be easily attached to and detached from the outer tank. Since it is necessary to connect to the discharge pipe provided in the above in a detachable and airtight manner, it is connected in the middle through a connecting means. Therefore, when the inner tank is installed in a fixed position on the outer tank,
The perforated plate provided on the outer periphery of the inner tank substantially closes the space with the inner wall of the outer tank, and the cleaning liquid that is injected from the center of the bottom of the outer tank and rises along the outer wall of the inner tank on average flows through the perforated plate to rectify the flow. Then, the object to be cleaned in the inner tank is uniformly poured from the upper edge of the inner tank. The contaminated cleaning liquid that has passed through the object to be cleaned and liberated contaminated fine particles is directly sucked into the discharge port at the bottom of the inner tank, but since the discharge port is airtightly connected to the discharge pipe provided at the bottom of the outer tank, The contaminated cleaning liquid is not mixed into the outer tank, and passes through the space between the inner tank and the outer tank and is discharged to the outside of the cleaning tank. The discharged contaminated cleaning liquid is sucked by a pump, cleaned through a filter, and then again injected into the cleaning tank from an injection port provided at the substantially central portion of the outer tank, and can be reused.

[0008]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a cross-sectional view showing an embodiment of a cleaning tank according to the present invention, FIG. 2 is a view showing a connection between an inner tank discharge port and a discharge pipe in the above embodiment, and FIG. 3 is a circulation filtration of a cleaning liquid in the above embodiment. It is a figure which shows the piping system at the time of performing and pure water rinse, respectively.

The cleaning tank of the present invention shown in FIG. 1 is composed of a double tank composed of an inner tank 1 and an outer tank 2, and the inner tank 1 is substantially equidistant from the inner wall of the outer tank 2 to the bottom surface thereof. And the upper edge of the inner tank 1 is sufficiently lower than the upper edge of the outer tank 2, and the cleaning liquid 4 injected into the cleaning tank from the injection port 3 provided at the center of the bottom of the outer tank 2 is Then, the gap between the inner tank 1 and the outer tank 2 is raised to cross the upper edge of the inner tank 1 and pour on the object to be cleaned 5 in the inner tank 1. A perforated plate 6 having a large number of small holes so as to substantially close the gap with the outer tank 2 is fixed to the upper part of the outer periphery of the inner tank 1 in parallel with the bottom surface. 4 is provided with a multi-plate hole at a position where it is sufficiently immersed in the substrate 4, and is used as a support base 7 for the article 5 to be cleaned. The gap between the inner tank 1 and the outer tank 2 is at least 20 mm or more in order to make the flow of the cleaning liquid 4 injected from the injection port 3 as uniform as possible. However, if the gap becomes large, the entire cleaning tank becomes large. Therefore, it is desirable to keep it to about 40 mm, and the perforated plate 6 fixed to the outer periphery of the inner tank 1 is provided with a large number of holes having a diameter of about several mm at even intervals, and In order to rectify the cleaning liquid 4 into the article to be cleaned 5 at a uniform flow rate, it must be provided at an appropriate position in the gap between the inner tank 1 and the outer tank 2, but it is easy to process because It is advisable to provide the outer wall of the tank 1 at a position lower than the upper edge by several tens of mm or more with a distance of 1 to 2 mm from the outer tank 2. Further, the support base 7 is provided with holes having a diameter of several mm at substantially uniform intervals over the entire surface thereof, and the contaminated cleaning liquid containing the contaminated fine particles is quickly flowed down at a uniform flow rate. At least 20 mm above the bottom of the tank.

When a large number of wafers placed in parallel in a cassette are placed on the support base 7 as the objects to be cleaned 5, the cleaning liquid passing between the cassettes and the wafers releases contaminated fine particles. The contaminated cleaning liquid containing these contaminated fine particles passes through the pores of the support base 7 and is discharged to the outside of the cleaning tank from the discharge port 8 provided on the bottom surface of the inner tank 1. However, since the inner tank 1 is detachably attached to the outer tank 2, the contaminated cleaning liquid discharged from the outlet 8 is prevented from affecting the clean cleaning liquid in the outer tank 2, It is necessary to lead to the discharge pipe provided outside, and for that purpose, the connecting means between the discharge port 8 of the inner tank 1 and the discharge pipe attached to the outer tank 2 is important.

An example of means for connecting the discharge port 8 of the inner tank 1 to the discharge pipe is a method using a ball joint as shown in FIG. 2 (a). The protruding tip of the discharge port 8 provided near the center of the bottom surface of the inner tank 1 is formed into a spherical shape, while the tip of the discharge pipe 10 provided inside the outer tank 2 so as to be fixed and penetrated near the center of the bottom surface of the outer tank 2. Is formed in a concave shape corresponding to the spherical surface of the protruding tip of the discharge pipe 8. When the inner tub 1 is installed at a fixed position in the outer tub 2, the spherical discharge port 8 is airtightly fitted to the tip of the concave discharge pipe 10, and like the spherical discharge port 8, the inner tub 1 is closed. The inner tub 1 can be stably held in the outer tub 2 with a constant gap, together with at least two projecting struts (not shown) provided so as to project outward from the bottom surface of the.

The connecting means shown in FIG. 2 (b) is a method using an O-ring seal joint, and as shown in the figure, the discharge port 8 provided at the center bottom surface of the inner tank 1 is It is formed so as to project in a tubular shape toward the outside. At the center of the bottom portion of the outer tub 2, a large outwardly projecting inlet port 3 is provided so that the tubularly projecting outlet port 8 can be easily inserted by providing a sufficient gap in the periphery and projecting in the tubular form. An O-ring seal joint 12 is fitted into a joint between the discharge port 8 and the protruding injection port 3 via an O-ring seal 11. The O-ring seal joint 12 has a discharge pipe connection port 10 and an injection pipe connection port 13. The bottom surface of the inner tank 1 is provided with a plurality of columns for keeping the distance between the inner tank 1 and the outer tank 2 constant (not shown). When the discharge port 8 of the inner tank 1 and the discharge pipe outside the outer tank 2 are connected by the O-ring seal joint, both the cleaning liquid inlet 3 and the contaminated cleaning liquid discharge port 8 are connected to the outer tank 2 and the inner tank 1, respectively. Since it is located in the center of the bottom of the tank, the flow of cleaning liquid flowing in the tank is rectified,
Therefore, efficient and uniform cleaning can be performed.

In order to circulate and filter the cleaning liquid in the cleaning tank of the present invention, the structure shown in FIG. 3 (a) is used. That is, the contaminated cleaning liquid discharged from the discharge port 8 of the inner tank 1 reaches the filter through the pump and the flow meter, the contaminated fine particles in the cleaning liquid are removed by the filter, and the cleaning liquid is cleaned again and then passed through the injection port 3. Although it is introduced into the outer tub 2, when such circulation filtration is carried out especially for a high temperature chemical liquid, a ball joint is used to connect the discharge port 8 and a discharge pipe provided outside the outer tub 2. It is suitable to use the method according to.

Next, FIG. 3B shows a piping system configuration in the case of rinsing with pure water after cleaning. Pure water pipe of required purity is connected to the inlet 3 through a filter to inject pure water into the outer tank 2. On the other hand, contaminated pure water which has passed through the support 7 in the inner tank 1 is pumped. , Is connected to the drainage drain through the flowmeter, and in this case, a method using an O-ring seal joint is suitable for connecting the discharge pipe.

As described above, the cleaning tank of the present invention has a two-tank structure in which it is detachably attached to the outer tank and a sufficient gap is secured between the inner tank and the outer tank. Since the cleaning solution is injected from the center of the bottom of the outer tank, it is poured at a uniform flow rate from the upper edge of the inner tank to the object to be cleaned, and contaminants released from the object to be cleaned diffuse widely into the cleaning tank. Without flowing down, it can be washed in a short time, and because it is connected to the discharge port outside the tank via the connecting means to the discharge port of the inner tank,
Not only is the production easy, but the above two tanks can be removed and each can be cleaned when necessary, and maintenance management is easy, so that the cleaning liquid can be prevented from being contaminated by sedimented particles at the bottom of the tank and efficient cleaning can be performed. .

[0016]

As described above, the cleaning tank according to the present invention uses a cleaning tank composed of a double tank including an inner tank and an outer tank, and substantially closes a gap between the outer tank and the outer peripheral portion of the inner tank. In addition to providing a perforated plate parallel to the bottom surface of the inner tank, an inner tank provided with a perforated plate on which the object to be cleaned is mounted as a support base at a position in the inner tank where the object to be cleaned can be sufficiently immersed in the cleaning liquid. The outer edge of the outer tank is sufficiently lower than the upper edge of the outer tank, and the outer tank has a structure in which it can be detachably installed inside the outer tank with a gap substantially equal to that of the outer tank. By connecting the discharge port of the cleaning liquid, which rises the gap of the inner tank and pours from the upper edge of the inner tank to the object to be cleaned, to the discharge pipe outside the tank through the connecting means, the cleaning liquid injected from the center of the outer tank is Distributed in a uniform manner to raise a sufficient gap with the inner tank, rectified by a perforated plate and poured onto the object to be cleaned from the upper edge of the inner tank. Since the contaminated cleaning liquid from which contaminated fine particles are released is discharged through the perforated plate of the support table to the outside of the tank through the discharge port provided near the center of the inner tank bottom, good cleaning can be performed in a short time, and Since the discharge port of the tank is connected to the discharge pipe outside the tank through the connecting means, the inner tank can be easily removed from the outer tank without the contaminated cleaning liquid leaking into the outer tank. Easy cleaning and maintenance management and efficient cleaning can always be performed.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a cleaning tank according to the present invention.

2A and 2B are views showing the connection between the inner tank discharge port and the discharge pipe in the above embodiment, FIG. 2A is a view showing a method using a ball joint, and FIG. 2B is a view showing a method using an O-ring seal joint. .

3A and 3B are diagrams showing a piping system for circulating and filtering cleaning liquid and rinsing with pure water in the above-mentioned embodiment, FIG. 3A is a diagram showing a case of circulating filtration of a cleaning liquid, and FIG. 3B is a diagram showing a case of rinsing with pure water. Is.

FIG. 4 is a diagram showing an example of a conventional cleaning tank.

[Explanation of symbols]

1 inner tank 2 outer tank 3 Injection port 4 Cleaning solution 5 Items to be cleaned 6 Perforated plate 7 Support 8 Ejection port 9 Ball joint 10 Discharge pipe 12 O-ring 14 Connection means

─────────────────────────────────────────────────── --- Continuation of the front page (56) References JP-A-8-31787 (JP, A) JP-A-6-61209 (JP, A) JP-A-1-242116 (JP, A) JP-A-4- 323824 (JP, A) JP 5-74753 (JP, A) JP 4-247621 (JP, A) JP 63-156533 (JP, A) JP 5-234978 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01L 21/304

Claims (3)

(57) [Claims] 1. A cleaning tank comprising a double tank consisting of an inner tank and an outer tank is used, and a perforated plate is provided in parallel with a bottom surface so as to substantially close a gap between the inner tank and the outer tank. An inner tank provided with a perforated plate on which the above-mentioned to-be-cleaned object is mounted as a support base is provided at a position within the inner tank where the to-be-cleaned object can be sufficiently immersed in the cleaning liquid. It is configured to be detachably installed inside the outer tank with a sufficiently low and almost equal gap around it, and it is injected from the injection port at the center of the bottom of the outer tank, and the gap between the outer tank and the inner tank is raised to A cleaning tank in which the outlet of the cleaning liquid that pours from the edge to the object to be cleaned is connected to a discharge pipe outside the tank via a connecting means. 2. The cleaning tank according to claim 1, wherein the connection means of the discharge port is connected to a discharge pipe installed in the outer tank via a ball joint. 3. The cleaning tank according to claim 1, wherein the connection means of the discharge port is connected to a discharge pipe provided outside the outer tank via an O-ring seal joint.