JP2023079400A - Cleaning tank and cleaning system - Google Patents

Abstract

To provide a cleaning tank capable of generating a vortex with high cleaning efficiency with a simple configuration as much as possible, and a cleaning system equipped with the cleaning tank.SOLUTION: A cleaning tank 12 includes a cylindrical body 22, a conical or spindle-shaped bottom 24 formed at the bottom of the body 22, a support 32 that supports at least one workpiece 34 disposed within the body 22, an inlet port 26 formed in a side surface of the body 22, positioned below the support 32, and configured to supply cleaning liquid into the body 22 for cleaning the workpiece 34, a jet nozzle 28 provided in the inlet port 26 and configured to generate a swirl flow of the cleaning liquid swirling around the central axis 42 of the body 22, and an outlet port 30 formed in the bottom 24 and configured to discharge the cleaning fluid.SELECTED DRAWING: Figure 2

Description

The present invention relates to a cleaning tank for cleaning workpieces such as semiconductor wafers and glass substrates, and a cleaning system including the cleaning tank.

In general, in the manufacturing process of semiconductor wafers and glass substrates, cleaning is performed to remove abrasives and fragments adhering to the wafers. In many cases, this cleaning is performed by immersing the object to be cleaned in a bath filled with cleaning fluid. Are known.

For example, Patent Literature 1 describes a technique for generating a spiral flow by supplying a cleaning liquid containing a microvalve from a nozzle arranged in a cleaning tank. Further, Patent Document 2 describes a technique for generating a swirl of the treatment liquid by using a storage tank having a helical wall surface. Furthermore, Patent Document 3 describes a technique in which a plurality of nozzles are provided in a processing tank so that the size of the vortex generated in the tank can be adjusted.

Japanese Patent Application Laid-Open No. 2019-201069 JP-A-2003-282512 JP 2009-239061 A

When a vortex is generated in a cleaning tank for efficient cleaning, it is important to determine the shape and size of the vortex to be generated at which position in the tank. On the other hand, it is preferable that the system including the washing tank be inexpensive, and for example, it is desired that the number of nozzles for generating vortices and associated means be as small as possible and have a simple structure. In addition, if the cleaning tank has a rectangular parallelepiped shape, dirt and the like separated from the object to be cleaned accumulates on the corners of the cleaning tank, making cleaning difficult.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a cleaning tank capable of generating a vortex with high cleaning efficiency with as simple a configuration as possible, and a cleaning system including the cleaning tank.

One aspect of the present disclosure is a cylindrical body, a conical or spindle-shaped bottom formed in the lower part of the body, and a support arranged in the body for supporting at least one object to be cleaned. an inlet port formed on a side surface of the body, positioned below the support and configured to supply cleaning liquid into the body for cleaning the object to be cleaned; a jet nozzle provided in the port and configured to generate a swirling flow of the cleaning liquid that swirls around the central axis of the body; and an outlet port formed in the bottom and configured to discharge the cleaning liquid. is a cleaning tank having

Another aspect of the present disclosure is a cleaning system comprising a cleaning vessel according to the above aspect and a cyclonic filter fluidly connected to the outlet port and the inlet port of the cleaning vessel.

According to the present disclosure, by arranging the inlet port of the cleaning tank below the support that supports the object to be cleaned in the cleaning tank, a swirl flow is generated throughout the tank, and the It is possible to obtain the effect that the separated foreign matter and the like can be efficiently discharged.

1 is a schematic configuration diagram of a cleaning system according to an embodiment; FIG. 2 is a schematic configuration diagram of a cleaning tank included in the cleaning system of FIG. 1; FIG. 3 is a cross-sectional view taken along the line AA' of FIG. 2; FIG. 3 is a cross-sectional view taken along the line BB' of FIG. 2; FIG. It is the figure which looked at the washing tank of FIG. 1 from upper direction.

FIG. 1 is a schematic configuration diagram of a cleaning system according to a preferred embodiment. The cleaning system 10 includes a generally cylindrical cleaning tank 12 , a cyclonic filter 14 , a pump 16 and a drain tank 18 . The pump 16 is configured to extract the cleaning liquid in the cleaning tank 12 , supply it to the filter 14 , and return the cleaning liquid filtered by the filter 14 back into the cleaning tank 12 . Also, the drain tank 18 is configured to collect the sludge 20 or the like separated from the cleaning liquid by the filter 14 and discharge it as drain.

FIG. 2 is a schematic configuration diagram of the cleaning tank 12. As shown in FIG. The cleaning tank 12 has a cylindrical body portion 22, a conical or spindle-shaped bottom portion 24 formed at the bottom of the body portion 22, and a side surface of the body portion 22, and is configured to supply a cleaning liquid. It has an inlet port 26, a jet nozzle 28 (see FIGS. 3 and 4 below) attached to the inlet port 26, and an outlet port 30 formed in the bottom 24 and configured to discharge cleaning liquid. Although not essential, the exit port 30 is preferably formed in the center of the bottom portion 24 from the standpoint of efficient discharge of cleaning fluid.

A support 32 is arranged on the upper side within the body 22 , and at least one (usually a plurality) of cleaning objects (works) 34 are supported on the support 32 . The workpiece 34 is, for example, a disk-shaped semiconductor wafer with a diameter of 100 mm to 200 mm (4 inches to 8 inches), and is dirty like an as-cut wafer obtained by cutting a single crystal ingot with an inner circumference cutting machine or a wire saw. It is attached. In the illustrated example, the workpieces 34 are arranged vertically on the support 32, but the support 32 may be configured to support the workpieces 34 in different directions in consideration of cleaning efficiency and the like. good too.

Although not essential, an ultrasonic oscillator 36 may be placed on the lower side of the cleaning tank 12 to further improve cleaning efficiency. As the ultrasonic oscillator 36, for example, what is known as a so-called drop-in type ultrasonic device can be used, and in many cases, it has a flat upper surface 38 as an ultrasonic oscillation surface. The use of the ultrasonic oscillator 36 makes it possible to remove even foreign substances firmly adhering to the workpiece 34 .

Next, the cleaning action of the cleaning tank 12 will be described. Here, it is assumed that the cleaning liquid (alkaline liquid, water, etc.) is filled up to the level indicated by the liquid surface 40 (for example, 100 liters), and the entire workpiece 34 is immersed in the cleaning liquid.

By operating the pump 16 ( FIG. 1 ) described above, the cleaning liquid is supplied into the cleaning tank 12 from the jet nozzle 28 attached to the inlet port 26 . Here, as shown in FIG. 3, the jet nozzle 28 is arranged and configured to discharge the cleaning liquid at a predetermined flow rate in a direction parallel to the tangential direction of the body portion 22 of the cleaning tank 12 which is substantially circular when viewed from above. It is Therefore, the cleaning liquid discharged from the nozzle 28 is guided by the inner wall of the body portion 22 of the cleaning tank 12 to form a swirl flow 44 that swirls around the central axis 42 of the cleaning tank 12 (body portion 22). As a result, a swirling flow as indicated by reference numeral 46 (FIG. 2) is also generated above the nozzle 28, and the work 34 is preferably washed by this.

More specifically, as shown in FIG. 4, foreign matter 50 such as wafer fragments, abrasive grains, oil, and ingot bonding bond scum adhering to the workpiece 34 is spread throughout the body 22 by swirling flows 44 and 46. It is separated from the workpiece 34 by the generated vortex and moved to the inner peripheral wall side of the body 22 by centrifugal force. Since the foreign matter 50 circulates in the vicinity of the inner wall of the body portion 22 and gradually sinks due to its own weight, it does not adhere to the workpiece 34 again. The cleaning tank 12 is particularly suitable for cleaning a work to which a lot of dirt is attached, such as an as-cut wafer formed by forming a single crystal ingot with an inner peripheral cutting machine (single cutting) or a wire saw (multiple cutting).

As shown in FIGS. 2 and 3, a swirling flow 48 parallel to the upper surface 38 of the ultrasonic oscillator 36 is generated along with the flow of the cleaning liquid along the direction 44, and the swirling flow 48 removes foreign substances 50 and the like from the upper surface 38. As shown in FIGS. is prevented from accumulating. Therefore, the ultrasonic oscillator 36 is always kept in a good condition so that its performance can be preferably exhibited.

The foreign matter 50 or the like that has settled down to the same height as the upper surface 38 of the ultrasonic oscillator 36 settles below the ultrasonic oscillator 36 due to the downward flow 52 . As shown in FIG. 5 , the foreign matter 50 is sucked below the ultrasonic oscillator 36 by the swirling flow 44 and the swirling flow 54 generated by the discharge of the cleaning liquid from the outlet port 30 . As described above, the bottom 24 of the cleaning tank 12 has a conical or fusiform shape, and the outlet port 30 is provided in the center (that is, the lowest part) of the bottom 24, so that the foreign matter 50 or the like settles and accumulates on the bottom 24. Instead, the strong swirling flow 54 within the cone or spindle ensures that it is expelled from the outlet port 30 . In addition, almost no foreign matter precipitates or accumulates on the inner wall or the bottom of the cleaning tank 12, so that the frequency and effort required for cleaning the inside of the cleaning tank can be reduced.

In this embodiment, by arranging the inlet port 26 (the jet nozzle 28) below (the support 32 that supports the work 34), a vortex swirling around the central axis 42 is generated throughout the tank, and foreign matter is removed. 50 etc. can be efficiently discharged and recovered as sludge 20 by a cyclonic filter 14 (see FIG. 1). For example, if the nozzle is placed at the top, the vortex flow gradually weakens toward the bottom of the washing tank, making it difficult to move sedimenting foreign matter to the outer circumference of the tank by centrifugal force. If the nozzle 28 is positioned downward as in the present embodiment, it is possible to guide the liquid around the jet and generate a vortex flow more efficiently (aspirator effect). It can be moved to the outside. Also, when the ultrasonic oscillator 36 is installed, it is possible to efficiently suppress adhesion or deposition on it. Further, if the nozzle is placed upward, the cleaning liquid may splash above the cleaning liquid, but if the nozzle is placed downward, the cleaning liquid will not splash.

In general, when a swirl flow is generated in a tank having a conical or spindle-shaped bottom, a swirl core is generated at the center of the flow. When the ultrasonic oscillator 36 is installed, depending on the arrangement conditions, etc., this pivot core may attenuate the ultrasonic waves and adversely affect the cleaning effect of the workpiece. 32, the ultrasonic oscillator 36 is arranged, so there is no turning core that could adversely affect the cleaning effect of the workpiece.

Also, as shown in FIG. 2, the inlet port 26 (jet nozzle 28) is positioned between the support 32 (lower end) and the ultrasonic oscillator 36 (upper surface 38) with respect to the height of the cleaning tank 12. Therefore, both the swirling flow 46 for cleaning the workpiece 34 and the swirling flow 48 for cleaning the upper surface 38 of the ultrasonic oscillator 36 can be efficiently generated by providing only one inlet port 26 . The height of the nozzle 28 can be appropriately set according to the dimensions and shapes of the support 32 and the ultrasonic oscillator 36. It is preferably set at or near the virtual liquid level 56 corresponding to /2. In this way, for example, when replacing the cleaning liquid, about half (about 50 liters in this case) of the old cleaning liquid is discharged from the cleaning tank 12, and about half of the remaining cleaning liquid is circulated by the jet nozzle 28, A stronger eddy current can be generated and the upper surface 38 of the ultrasonic oscillator 36 can be cleaned more efficiently.

A plurality of inlet ports 26 (jet nozzles 28) may be provided, but one jet nozzle is sufficient to generate the swirling flow 44 as described above. Therefore, according to this embodiment, the cleaning tank 12 capable of efficient cleaning with a simpler structure is provided. In this embodiment, an example in which the ultrasonic oscillator 36 is installed has been described.

Referring to FIG. 1 again, the cleaning system 10 can perform the extraction of cleaning liquid from the cleaning tank 12 and the supply of the extracted cleaning liquid to the cyclone filter 14 with one pump 16. By using the system, the cost of the entire system can be reduced. In general, a cyclone filter is not used in a semiconductor cleaning process, but in this embodiment, the cyclone filter 14 is used to remove the foreign substances 50 and the like as sludge 20 from the clean cleaning liquid from the filter 14. can be returned into the cleaning tank 12 by using the discharge flow of , it is possible to construct an efficient cleaning system with a small number of parts. However, between the outlet of the cyclone filter 14 and the inlet port 26 of the washing tank 12, a filter (not shown) of a type that replaces the filter medium may be provided. In general, in a filter medium exchange type filter, it is necessary to replace the filter medium when clogging occurs. However, in this embodiment, the cyclone filter 14 can remove relatively large foreign matter, so the frequency of filter medium replacement is greatly reduced. can do.

REFERENCE SIGNS LIST 10 cleaning system 12 cleaning tank 14 cyclone filter 16 pump 18 drain tank 20 sludge 22 body 24 bottom 26 inlet port 28 jet nozzle 30 outlet port 32 support 34 workpiece 36 ultrasonic oscillator 50 foreign matter

Claims (5)

a cylindrical body;
a conical or spindle-shaped bottom formed at the bottom of the body;
a support positioned within the barrel for supporting at least one object to be cleaned;
an inlet port formed on a side surface of the body, disposed below the support, and configured to supply cleaning liquid into the body for cleaning the object to be cleaned;
a jet nozzle provided at the inlet port and configured to generate a swirling flow of cleaning liquid that swirls around the central axis of the body;
an outlet port formed in the bottom and configured to discharge the cleaning liquid;
washing tank. 2. The cleaning vessel of claim 1, further comprising an ultrasonic oscillator positioned between said support and said outlet port. 3. The cleaning bath according to claim 2, wherein the jet nozzle is arranged between the lower end of the support and the upper surface of the ultrasonic oscillator with respect to the height of the cleaning bath. a cleaning tank according to any one of claims 1 to 3;
a cyclonic filter fluidly connected to the outlet port and the inlet port of the cleaning vessel;
cleaning system. 5. The cleaning system of claim 4, comprising a single pump configured to withdraw the cleaning liquid from the cleaning tank and pass the extracted cleaning liquid through the cyclonic filter and back to the cleaning tank.

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