JP2001198417A - Method for recovering matter to be removed in fluid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such a problem that all of ground and cut refuses generated by dicing or by machining such as CMP, or the like, are together mixed within a tank heretofore and a substance severe in environmental standards is also mixed to be treated along with these refuses and, therefore, the amount of waste becomes very much and it is impossible to recover the waste to reuse the same. SOLUTION: Wastewaters are classified by materials of matter to be removed or by impurities in the matter to be removed and highly concentrated in separate filter devices 53 to recover matters to be removed in wastewaters in separate recover devices 68.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for recovering an object to be removed from a fluid.

[0002]

2. Description of the Related Art At present, reduction of industrial waste, separation and reuse of industrial waste, or prevention of discharge of industrial waste to the natural world are important themes from an ecological point of view. This is a corporate challenge for the future. In this industrial waste, there are various fluids containing the substances to be removed.

[0003] These are expressed in various terms such as sewage, drainage, and waste liquid. Hereinafter, a substance containing a substance to be removed in a fluid such as water or a chemical will be referred to as drainage. I do. These wastewaters are subjected to an expensive filtration treatment device or the like to remove the object to be removed, and the wastewater is reused as a clean fluid, or the separated object to be removed or the one that cannot be filtered is treated as industrial waste. ing. In particular, water is returned to the natural world, such as a river or sea, in a clean state that meets environmental standards by filtration, or is reused.

[0004] However, it is very difficult to adopt these devices because of problems such as equipment costs such as filtration treatment and running costs, which is also an environmental problem.

[0005] As can be seen from this fact, wastewater treatment technology is an important problem from the viewpoint of environmental pollution and recycling, and a system with low initial cost and low running cost is urgently desired. ing.

As an example, wastewater treatment in the semiconductor field will be described below. In general, when grinding or polishing a metal, semiconductor, ceramic, or other plate-like body, it is necessary to prevent a rise in temperature of a polishing (grinding) jig due to friction, to improve lubricity, to adhere grinding chips or cutting chips to the plate-like body. Therefore, a fluid such as water is showered on a polishing (grinding) jig or a plate-like body.

Specifically, when dicing a semiconductor wafer which is a plate-like body of a semiconductor material, a method of flowing pure water to a dicing blade or a wafer has been adopted. In the dicing apparatus, as shown in FIG.
To prevent the temperature of the wafer W from rising,
In order to prevent the pure water from adhering to the semiconductor wafer W, a nozzle SW for discharging water is attached and showered so that the pure water hits the blade DB. Then, the drainage is transported outside via a pipe attached to the tray BL.

When the thickness of a wafer is reduced by back grinding, pure water is flown for the same reason. That is, the wafer 201 provided on the turntable 200 as shown in FIG.
4 to wash the pure water by showering. The discharged wastewater is transported to the outside by a pipe attached to the tray 203.

The wastewater mixed with grinding dust or polishing waste discharged from the above-mentioned dicing device or back-grinding device is filtered to be clean water and returned to the natural world, or is reused. Has been recovered. However, since dicing waste and back-grinding waste are processed together in a tank, it is virtually impossible to separate and collect the waste.

In the current semiconductor manufacturing, there are two methods of treating wastewater mixed with an object to be removed (dust) mainly composed of Si, a coagulation sedimentation method, and a method combining a filter filtration and a centrifugal separator. .

In the former coagulation precipitation method, PA is used as a coagulant.
C (polyaluminum chloride) or Al2 (SO4) 3
(Sulfuric acid band) or the like was mixed in the wastewater to generate a reaction product with Si, and the reaction product was removed to filter the wastewater.

[0012] In the latter method combining filter filtration and centrifugal separation, the wastewater is filtered, the concentrated wastewater is centrifuged to collect silicon waste as sludge, and the clean water formed by filtering the wastewater is removed. Was released to the natural world or reused.

For example, as shown in FIG. 15, waste water generated at the time of dicing or back grinding is collected in a raw water tank 301, and is filtered by a pump 302 by a filtration device 30.
Sent to 3. Since the filtering device 303 is equipped with a ceramic or organic filter F, the filtered water is sent to a recovered water tank 305 via a pipe 304 and reused. Or released to nature.

On the other hand, the filtering device 303 is periodically cleaned because the filter F is clogged. For example, the valve B1 on the raw water tank 301 side is closed and the valve B
3 and valve B2 for sending wash water from raw water tank
Is opened, and the filter F is backwashed with the water in the recovered water tank 305. The wastewater mixed with the high-concentration Si waste generated thereby is returned to the raw water tank 301. The concentrated water in the concentrated water tank 306 is transported to the centrifugal separator 309 via the pump 308, and is separated into sludge (sludge) and a separated liquid by the centrifugal separator 309. The sludge composed of Si waste is collected in a sludge collection tank 310, and the separated liquid is collected in a separated liquid tank 311. Further, the drainage of the separated liquid tank 311 in which the separated liquid is collected is transported to the raw water tank 301 via the pump 312.

These methods include, for example, Cu, Fe, A
l, solid or plate-like material mainly composed of a metal material, grinding of solid or plate-like material such as ceramics,
It has also been employed when collecting debris generated during polishing.

On the other hand, CMP (Chemical-Mechanical Poli
shing) has emerged as a new semiconductor process technology. The CMP is a technique for polishing the upper and lower surfaces of an interlayer insulating film for the purpose of planarizing the upper surface of the interlayer insulating film that covers the wiring in order to realize an ideal multilayer wiring structure of a semiconductor device.

First, a flat device surface shape can be realized by this CMP technique. As a result, a fine pattern can be formed with high accuracy by using a lithography technique, and the possibility of realizing a three-dimensional IC can be brought about by using an Si wafer bonding technique together.

Second, an embedded structure of a material different from that of the substrate can be realized. As a result, there is an advantage that the embedded structure of the wiring can be easily realized. Conventionally, tungsten (W) embedding technology for embedding W in an interlayer film in a multi-layer wiring of an IC by a CVD method and etching back the surface to flatten the surface has been adopted, but recently, it is more preferable to flatten the surface by CMP. The process can be simplified, and CMP is in the spotlight.

The techniques and applications of these CMPs are described in detail in "Science of CMP" published by the Science Forum.

Next, the mechanism of CMP will be briefly described.
As shown in FIG. 16, a polishing cloth 451 on a rotary platen 450 is provided.
A semiconductor wafer 452 is placed on the
By rubbing while pouring 3, polishing, and chemical etching, irregularities on the surface of the wafer 452 are eliminated. The surface is planarized by the chemical reaction of the solvent in the abrasive 453 and the mechanical polishing action of the polishing cloth and the abrasive grains in the abrasive. As the polishing cloth 451, for example, foamed polyurethane, non-woven fabric, or the like is used. The abrasive is a mixture of abrasive grains such as silica and alumina in water containing a pH adjuster, and is generally called a slurry. I have. While the slurry 453 is flowing, the wafer 452 is placed on the polishing pad 451.
Are rotated and a constant pressure is applied to rub them. Reference numeral 454 denotes a dressing unit for maintaining the polishing ability of the polishing pad 451 and for keeping the surface of the polishing pad 451 dressed. M1 to M3 are motors, and 455 to 457 are belts.

The above-described mechanism is constructed as a system. This system is roughly divided into a wafer cassette loading and unloading station,
It comprises a wafer transfer mechanism, a polishing mechanism, a wafer cleaning mechanism, and a system control for controlling these.

First, the cassette containing the wafer is placed in a wafer cassette loading / unloading station, and the wafer in the cassette is taken out. Subsequently, the wafer is held by a wafer transfer mechanism, for example, a manipulator, and a rotary platen 450 provided in the polishing mechanism is held.
And the wafer is planarized using CMP technology. When the flattening operation is completed, the wafer is moved to a wafer cleaning mechanism by the manipulator and cleaned in order to clean the slurry. Then, the washed wafer is stored in a wafer cassette.

For example, the amount of slurry used in one process is about 500 CC to 1 liter / wafer. Also,
Pure water flows through the polishing mechanism and the wafer cleaning mechanism.
These drains are finally combined at the drain, so that about 5 to 10 liters / wafer of drainage is discharged in one flattening operation. For example, in the case of a three-layer metal, about seven times of flattening work is performed by flattening the metal and flattening the interlayer insulating film, and by the time one wafer is completed,
Seven times the drainage of 5 to 10 liters is discharged.

Therefore, when a CMP apparatus is used, a considerable amount of slurry diluted with pure water is discharged, and a method for efficiently treating the wastewater has been regarded as a problem. At present, these wastewaters have been treated by a conventional method that combines the coagulation sedimentation method and the filter filtration and centrifugation shown in FIG.

[0025]

However, in the former coagulation-sedimentation method, a chemical is fed as a coagulant. However, it is very difficult to specify the amount of a completely reacting chemical, and a large amount of the chemical is inevitably introduced and unreacted chemical remains. Conversely, if the amount of the chemical is small, all the objects to be removed are not aggregated and settled, and the objects to be removed remain without being separated. In particular, when the amount of the drug is large, the drug remains in the supernatant. When this is reused, there is a problem that chemicals remain in the filtration fluid, so that those which dislike the chemical reaction cannot be reused.

For example, in the case of dicing, the waste water is composed of silicon chips and distilled water, and the filtered water causes an undesired reaction when it is flown on a wafer because a chemical remains therein. There was a problem that was not available.

Floc, which is a reaction product between the chemical and the substance to be removed, is generated as a floating substance such as algae. Conditions for forming this floc are strict PH conditions, and a stirrer, P
An H measuring device, a coagulant injection device, a control device for controlling these devices, and the like are required. In addition, a large sedimentation tank is required to stably settle flocs. For example, 3m3
/ 1 hour wastewater treatment capacity, a tank with a diameter of about 3 meters and a depth of about 4 meters (settling tank of about 15 tons)
Is required, and if the entire system is used, the site will be a large-scale system requiring a site of about 11 m × 11 m.

In addition, some flocs are suspended in the sedimentation tank without being settled, and there is a possibility that these flocks may flow out of the tank, and it is difficult to collect all of them. That is, there are problems such as the size of the equipment, the high initial cost of this system, the difficulty in reusing water, and the high running cost resulting from the use of chemicals.

On the other hand, as shown in FIG. 15, in a method in which a filter filtration of 5 m3 / 1 hour is combined with a centrifugal separator, a filter F (called a UF module, which is composed of a polysulfone fiber, Since a ceramic filter is used, water can be reused. However, four filters F are attached to the filtering device 203, and it is necessary to replace a high-priced filter of about 500,000 yen / filter at least once a year from the life of the filter F. Moreover, the pump 202 before the filtering device 203 has a large motor load because the filter F is a pressurized filtering method, and the pump 202 has a high capacity.
Also, about 2/3 of the drainage passing through the filter F is:
It had been returned to the raw water tank 201. Further, since the wastewater containing the substance to be removed is transported by the pump 202, the pump 202
The inner wall of the pump 2 was shaved, and the life of the pump 2 was very short.

Summarizing these points, there is a problem that the running cost is very large because the electricity cost for the motor is very high and the replacement cost of the pump P and the filter F is expensive.

Further, in the CMP, an incomparable amount of wastewater is discharged in comparison with the dicing process. Moreover, the particle size of the abrasive mixed in the slurry is 0.2 μm, 0.1 μm.
m, 0.1 μm or less. Therefore, when the fine abrasive particles are filtered with a filter, the abrasive particles enter the pores of the filter and immediately cause clogging, and clogging occurs frequently. Therefore, there is a problem that a large amount of wastewater cannot be treated.

In the method of coagulating sediment to be removed (dicing debris, polishing debris or abrasive grains) in the waste water, there is also a problem that it is difficult to reuse the substance to be removed because the substance to be removed is chemically reacted. Was. As can be seen from the above explanations, in order to remove as much as possible substances harmful to the global environment, or to reuse filtration fluids and separated materials to be removed, various filtration devices for wastewater are used. , The system becomes large-scale, and the initial cost and running cost are enormous after all. Therefore, conventional sewage treatment equipment
It was not a system that could be adopted at all.

Also, dicing waste, back grinding waste,
Backlapping waste is collectively drained into one tank, and some of the waste has very strict environmental standards. It was virtually impossible to sort out and remove the material containing impurities. The same applies to the drainage of CMP.

[0034]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems. First, a fluid mixed with an object to be removed having impurities introduced therein is substantially distinguished by the material of the impurities. This problem is solved by taking out the fluid filtered for each fluid classified by the impurity material and collecting the remaining object to be removed for each of the classified impurities.

Second, a first fluid mixed with a first impurity having a first impurity is introduced into a first tank, and a second fluid having a second impurity is introduced into a second tank. Second mixed with
, The filtered fluid is taken out from the first tank and the second tank, and the mixing ratio of the object to be removed is increased,
The first fluid and the second fluid having an increased mixing ratio of the object to be removed are transferred to a first recovery tank and a second recovery tank, respectively, and are transferred to the first tank and the second recovery tank. Removing the fluid by the provided fluid removing means,
The problem is solved by separately collecting the first object to be removed and the second object to be removed remaining in the first and second collection devices.

Since the substance to be removed containing a specific impurity can be sorted and recovered, the impurity can be easily reused or discarded in a later step. In particular, an object to be removed containing impurities having strict environmental standards is not collected and collected together with other objects to be removed, so that the collection efficiency is improved.

Third, the first tank is configured to filter a part of the first fluid with the first fluid by using a filter comprising at least a part of the first object to be removed contained in the first fluid. Out of the tank, and in the second tank, a part of the second fluid is filtered in the second tank by a filter comprising at least a part of the second object to be removed contained in the second fluid. This is solved by using the first fluid and the second fluid having an increased mixing ratio of the object to be removed.

Fourth, the first tank removes a part of the first fluid from the first tank with a filter made of the first object to be removed contained in the first fluid. In the second tank, a part of the second fluid is taken out of the second tank by a filter made of a second substance to be removed contained in a second fluid, and the mixing rate of the substance to be removed is reduced. The above problem is solved by using the first fluid and the second fluid, each of which has an increased pressure.

If the material to be removed is captured by a filter made of the material to be removed and the particle size distribution of the material to be removed is wide, the filter is set to 0.1.
Fine particles of 1 μm or less can be captured. Therefore, most of the objects to be removed can be sorted and collected.

Fifth, the first fluid in the first tank is transferred to the first tank.
Circulating through a support filter of the first support filter to form a first multilayer filter made of the object to be removed on the surface of the first support filter, and a part of the first fluid is applied to the first multilayer filter by the first multilayer filter. The problem is solved by taking out from the first tank and using the first fluid with an increased mixing ratio of the first object to be removed.

By putting the supporting filter into the drainage and sucking the fluid through the supporting filter, a laminated filter made of the object to be removed can be easily formed. Moreover, since a filter having a higher filtration accuracy than that of the support filter can be formed, most of the objects to be removed can be selected and collected.

Sixth, the first tank is a filter made of a solid substance different from the first substance to be removed contained in the first fluid, and a part of the first fluid is removed from the first tank. In the second tank, a part of the second fluid is taken out of the second tank with a filter made of a solid substance different from the second substance to be removed contained in the second fluid, and The first fluid and the second fluid having an increased mixing ratio of the removed matter are used as the first fluid and the second fluid, and the first fluid and the second fluid having an increased mixing ratio of the removal object are collected in a first recovery tank and a second fluid. 2 and the fluid was removed by the fluid removing means provided in the first and second recovery tanks, and remained in the first and second recovery devices. What is solved by separately collecting the first and second objects to be removed A.

Seventh, a first laminated filter made of a solid material different from the first object to be removed formed on the surface of the first support filter is immersed in the first fluid in the first tank. ,
The problem is solved by taking out a part of the first fluid from the first tank with the first laminated filter and forming the first fluid with a higher mixing ratio of the first object to be removed. is there.

If a filter made of a solid material is formed in advance and the material to be removed is captured, fine particles (less than 0.1 μm) in the CMP wastewater, which had been very difficult to capture in the past, can also be captured. It can be recovered for each material and each impurity of the material to be removed.

Eighth, the first laminated filter is solved by including first objects to be removed having different sizes.

Ninth, the first object to be removed contains particles of different sizes, and the size of the pores of the first support filter is larger than the particle size of the smallest particles and the size of the largest particles. The problem is solved by being smaller than the particle size.

[0047]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, an outline of a method of removing an object to be removed from a fluid will be described with reference to FIGS.

FIG. 1 shows a filtration device 53 for filtering waste water, in which objects to be removed mixed in the waste water are separately collected according to the type of impurities mixed in the object to be removed. Things.

For example, a silicon wafer is sliced from a silicon ingot containing specific impurities, and the sliced wafer is cut by dicing, back grinding, back lapping, CMP, or the like, so that a total of two thirds or more of the ingot is formed. It becomes silicon waste.

Therefore, by collecting and reusing these wastes, an environment-friendly system can be realized. Furthermore, if the impurities introduced into the silicon are focused on and collected substantially separately, the silicon can be recovered. It remelts and becomes easy to reuse as a substrate of a semiconductor device. In addition, impurities having extremely strict environmental standards can be recovered by sorting out silicon waste containing the impurities.

In particular, waste generated when slicing a crystal ingot made of a semiconductor material into wafers has the same composition and the same impurity composition as the crystal ingot, and thus is very effective in recovery. For example, in a factory that manufactures semiconductor wafers, if the generated debris is collected according to the composition of the crystal ingot, the debris can be reused as the material of the crystal melt when manufacturing the ingot.

In CMP and the like, the polishing process is separated by a metal material such as Al, Cu, and tungsten, and the abrasive material is also separated. Therefore, it is possible to collect each metal material and to collect each abrasive grain.

Further, phosphorus, antimony, arsenic, boron and the like are used as impurities of the semiconductor. In particular, since arsenic is a harmful substance, arsenic can be collected in a concentrated manner by separately collecting wastewater containing this substance. That is, by selectively recovering a portion where the mixing ratio of the specific impurity is high, the object to be removed can be selectively recovered.

The drainage tanks 50 are separately prepared according to the composition of the substance to be removed contained in the wastewater or impurities in the substance to be removed. For example, the first drainage tank 50
A and a second drainage tank 50B are provided, and the first drainage 52 that has washed out dicing debris (removed material) containing arsenic is provided.
A is stored in the first drainage tank 50A, and the second drainage 52B that has washed away dicing debris into which arsenic does not enter is stored in the second drainage tank 50B. Then, the wastewater is made highly concentrated by the filtering devices 53A and 53B prepared respectively, and collected separately by the collecting devices 68A and 68B.

According to this method, not only arsenic but also other impurities, in the case of CMP, metal materials or types of abrasive grains, the drainage can be stored in different drainage tanks, and these can be collected separately.

FIG. 2 specifically illustrates one of the multiple collection systems shown in FIG.
Fluid is removed from the wastewater stored in the drain tank 5
When the concentration of the object to be removed is increased to a predetermined concentration, the wastewater is transferred to the collecting device 68, the fluid is removed again by the collecting device 68, and the object to be removed (recovered) captured by the filter FTb and formed in a sandy state Object) 75 is collected. Further, the wastewater is filtered by the filtration device 53, and the filtration fluid is reused. As a recovery method, air in the second storage tank 73 located below the filter membrane FTb is sucked through a pipe 74, and the fluid is transferred to the second storage tank 73 using a pressure difference.

Above the drain tank 50, a pipe 51 is provided as a drain supply means. This pipe 51
Is a place where the fluid mixed with the object to be removed passes. For example, in the field of semiconductors, the pipe 51 is a place through which drainage mixed with an object to be removed flowing from a dicing device, a back grinding device, a mirror polishing device, or a CMP device passes. In the case of a wafer maker, it is a place where wastewater mixed with an object to be removed generated when slicing a wafer passes.

In the drainage 52 stored in the drainage tank 50, a plurality of suction-type filtration devices 53 are provided. Below the filtering device 53, an air bubble generating device 54 is provided, for example, such as a small hole made in a pipe, or a bubbling device if used for a fish tank, so that it just passes through the surface of the filter membrane. Its position has been adjusted. 55 is an air blow.

The pipe 56 fixed to the filtration device 53 is
The fluid that has been suctioned and filtered passes, and the fluid that has passed through the pipe 56 passes through a first valve 58 to a drain tank 50.
Pipe 59 going to the side, reused (or drained)
It is selectively transported to a pipe 60 directed to the side. A second valve 61, a third valve 62, a fourth valve 63, and a fifth valve 64 for transferring waste water to the collection device 68 are attached to the side wall and the bottom surface of the drain tank 50, and pipes 65, 66 are provided. Extend to the collection device 68.

The sensor 67 constantly senses the concentration of the substance to be removed in the filtered fluid passing through the pipe 60. As the sensor, an optical sensor with a light receiving / light emitting element is preferable because it can always measure. The light emitting element may be a light emitting diode or a laser. Also, the sensor 67
May be attached in the middle of the pipe 56 or in the middle of the pipe 59. Reference numeral 70 denotes a pressure gauge for detecting the pressure of the filtered water passing through the pipe 56, and reference numeral 71 denotes a flow meter.

On the other hand, the drain tank is concentrated with time. When the concentration of the wastewater tank 50 containing the material to be removed reaches a predetermined concentration, the wastewater is transported to the collection device 68,
In the recovery device 68, the fluid and the object to be removed are separated. The collecting device 68 is divided into a first storage tank 72 and a second storage tank 73, and a filter F is provided between the two storage tanks 72 and 73.
Tb is arranged. Then, by suctioning the pipe 74 with a pump or the like, the pressure in the second storage tank 73 is reduced, and the wastewater is forcibly transferred to the second storage tank 73.

As a result of this suction, an aggregate (collected material) 75 of the material to be removed, such as a lump of sand, is placed on the filter FTb.
Is generated, and the collected material 75 is collected in a container 76. Since the collected matter is scattered when dried, the container is composed of a sealed case or bag in which the fluid does not evaporate. FIG.
Describes the collection mechanism of the collection device 68.

FIG. 3A is a drawing in which the drainage 82 is stored in the first storage tank 72 and the fluid is transferred to the second storage tank 73 by suction. The second storage tank 73 is a container for fluid having an opening on the upper side, and a suction pipe 74 and a pipe 80 for discharging fluid are provided on a side surface. Pipe 74
Is installed above the fluid level in the second storage tank 73 to suck the air in the second storage tank 73. The fluid is returned to the drain tank 50 of FIG. 2 via the pipe 80. A first storage tank 72 is placed on the second storage tank 73, and a hole through which a fluid can pass is provided on the bottom surface of the first storage tank 72 corresponding to the opening of the second storage tank 73. There are many. Further, filters FTb and FTc for capturing an object to be removed are provided in a drain passage from the first storage tank 72 to the second storage tank 73.

On the other hand, a collection tank 81 is provided in the first storage tank 72. The recovery tank 81 has a mechanism that can be removed from the first storage tank 72. This collection tank 81
A filter FT is also provided on the bottom
b is provided. Drainage 8 from pipe 66
2 falls into the second storage tank 73 by vacuum suction of the pipe 74. At this time, the object to be removed is captured by the filter FTb and stacked, and finally, most of the drainage is removed and only the object to be removed remains in the recovery tank 81.

Here, the filter has a large hole so that the fluid can easily move to the second storage tank 73. This is because it is not necessary for the recovery device 68 to separate all the objects to be removed. That is, the first purpose is to reduce the concentration of the drainage tank 50, and the second purpose is to collect the object to be removed at a high speed because rough filtration may be used. Also, the holes of the filters FTb and FTc are large,
Even if the material to be removed is mixed in the storage tank 73 of
Since it is returned to the drain tank 50 at 0, there is no problem at all.

FIG. 3B shows a state in which the object to be removed 83 is captured in the form of sand in the recovery tank 81. The collection tank 81
This collection tank 81 can be removed from the first storage tank 72.
May be removed and collected as it is, or an object to be removed may be collected in a container 83 prepared separately.

Further, as shown in FIG. 3C, a push-up device 84 may be employed to collect the data without human assistance. That is, the collection tank 81
Then, the filter FTb is pushed up by the pushing-up means 85, and the collected material 75 is moved to the collection tank 81. Then, the collected material 75 is moved by a squeegee or the like, and placed in a container 83 as shown in FIG. 3D. Also, the filter FTb and the filter FTb may be grasped by a manipulator and stored in the container 83.

Then, as shown in FIG. 3E, the containers 83 are stacked and collected at one time. Here, the container is given a code so that the collected material (especially the material, composition, and impurities in the material to be removed) contained therein can be easily identified at the collection destination. . Next, the actual collection device 68 will be described with reference to FIG. FIG. 4a is a sectional view of the collecting device 68, and FIG.
Is a perspective view of a second storage tank 73. FIG. FIG. 4c shows the second
Shows a support plate and a filter provided on the storage tank 73 of FIG.
7. Two PVC plates 89 having openings 88 are shown. FIG. 4d shows the first storage tank 72, in which an opening 90 is provided on the bottom surface. FIG. 4e shows the thing laid on the bottom of the first storage tank 72, and shows a support plate 91, a filter 92 made of a resin sheet called a saran net from below, and a collected material 75 laminated thereon. .

As can be seen with reference to FIG. 4a, a rubber packing 93 is provided on the edge 92 of the second reservoir 73, on which the laminate of FIG. 4c is provided. The stainless steel plate 86 supports a nylon net 87 and a PVC plate 89 having a filter function, and has a large number of holes of about 10 mmφ in a portion corresponding to the opening of the second storage tank 73. The nylon net 87 has a hole diameter of about 10
A filter of μm prevents diatomaceous earth described later from flowing into the second storage tank 73. The openings 88 of the two PVC plates 89 are filled with commercially available diatomaceous earth, for example, to have a filtering function. The diatomaceous earth has a particle size larger than the pore diameter of the lower layer nylon net, and a smaller diameter particle is spread toward the upper layer. Further, here, two PVC plates 89 are employed in order to form the diatomaceous earth thickly, but at least one plate is sufficient in principle. Further, instead of diatomaceous earth, another solid matter may be employed. For example, zeolite can be adopted.

A first storage tank 72 is provided on the PVC plate 89. Further, the first storage tank 72 and the second storage tank 73 are integrated, and the edges 92 and 94 are clamped so that fluid does not flow from between them. Although the first storage tank 72 and the second storage tank 73 are divided in consideration of the refilling of the nylon net 87 and diatomaceous earth, they may be formed integrally. Diatomaceous earth is also laid on the opening 90 on the bottom surface of the first storage tank 72.

The first storage tank 72 is provided with a collection tank 81 which can be taken in and out. A plurality of fluid passages are also provided on the bottom surface of the recovery tank 81, and a laminate shown in FIG. 4E is provided on the bottom surface. The saran net 92 captures the objects to be removed and is gradually laminated to form a collection having a predetermined thickness. The support plate 91 is made of a plate having a certain strength, and as shown in FIG. 75 serves as a support plate for pushing up. The material of the support plate 91 may be metal or plastic.

The wastewater having a high concentration in the wastewater tank 50 shown in FIG. 2 is transferred from the pipes 65 and 66 to the first storage tank 72. Then, vacuum suction is performed by a pump attached to the pipe 74, and the drainage is filtered and the fluid is transferred to the second storage tank 73. In other words, the drainage water is drained by multiple filters of the Saran net 92, the diatomaceous earth 95 provided at the opening 90 of the first storage tank 72, the diatomaceous earth 95 provided at the opening 88 of the PVC plate 89, and the nylon net 87. The material to be removed is captured. Then, while the suction is continued, the objects to be removed are stacked on the saran net 92 to have a thickness that can be collected.

Then, the recovery tank 81 is taken out of the recovery device 68 and placed on the push-up device 84 shown in FIG. 3C. The push-up device 84 is provided with push-up means 85, and the push-up means 85 comes into contact with the support plate 91 through the opening 90, and the collected material including the support plate is pushed upward. In this state, the collected material 75 can be stored in the container 83. Now, the principle of the filtering device 53 will be described. In the description of the invention, the matter to be removed and the solid matter are used properly in the text, so they are defined. The former matter to be removed is a substance contained in wastewater to be filtered, and is an individual.

The latter solid substance refers to a constituent material of a filter membrane in which solid substances are collected to form a layer like sand in order to filter waste water containing the substance to be removed. For example, the solid matter is laminated on the first filter membrane, and the laminated membrane has a higher filtration accuracy than the filtration accuracy of the first filter membrane. And can be moved.

The object to be removed is, for example, 500 μm to 0.1 μm.
m, a large amount of particles with a wide distribution of
μm, 0.2 μm, 0.1 μm or less, a large amount of particles having a narrow distribution, and the former is an object to be removed generated by, for example, dicing, back grinding or back wrap, and the latter is a CMP. Semiconductor particles, metal chips, and / or
Or, the material is insulating film waste.

The solid substance is a substance distributed at about 500 μm, for example, a semiconductor material such as Si, an insulating substance such as alumina, a cutting waste such as a metal, an abrasive waste or a crushed waste. Solid materials with a distribution, such as diatomaceous earth and zeolites. Next, the point that the aggregate of the object to be removed and / or the aggregate of the solid matter can be used as a filtration membrane having high filtration performance will be described.

First, the inventor considered using the object to be removed as a filter membrane to filter the object to be removed contained in the stock solution in the tank.

For example, an object to be removed is generated when a crystal ingot is sliced into a wafer, when a semiconductor wafer is diced, or when a back grinding is performed, and is mainly made of a semiconductor material, an insulating material, and a metal material. Yes, S
i, organic materials such as silicon oxide, Al, SiGe, and sealing resin, and other insulating film materials and metal materials. In the case of a compound semiconductor, a compound material such as GaAs is applicable.

Recently, dicing has been adopted in the manufacture of CSP (chip scale package).
In this method, the surface of the wafer is coated with a resin, and finally the resin and the wafer that are sealed are diced together. Further, there is a semiconductor device in which semiconductor chips are arranged in a matrix on a ceramic substrate, a resin including the ceramic substrate is covered, and finally, the sealed resin and the ceramic substrate are diced. These also generate objects to be removed when dicing.

On the other hand, there are many places where objects to be removed are generated even in fields other than the semiconductor field. For example, in the industry that uses glass, liquid crystal panels, panels of EL display devices, and the like perform dicing of a glass substrate, polishing of a side surface of the substrate, and the like. In addition, electric power companies and steel companies use coal as fuel, and the powder generated from coal corresponds to this, and the powder mixed in the smoke emitted from the chimney also corresponds to the removed material. The same applies to powders generated from mineral processing, jewelry processing, and tombstone processing. Furthermore, metal scrap generated when processing with a lathe, etc.,
Ceramic dust and the like generated by dicing, polishing and the like of a ceramic substrate or the like correspond to the above.

These debris are generated by processing such as polishing, grinding, or pulverization. The debris is taken into a fluid such as water or a chemical to remove the debris, and is generated as wastewater.

Then, a filter is formed from the object to be removed,
The filtering for removing the object to be removed will be described with reference to FIGS. 5, 6, and 7. FIG.

As described above, there are various combinations of the fluid and the object to be removed. Here, water is used as the fluid, and the water contains the dicing dust of the semiconductor wafer as the cut object. Will be explained as if it were included.

Reference numeral 10 in FIG.
Is a filter hole. The film formed in a layer on the opening of the filter hole 11 and the surface of the supporting filter film 10 is an aggregate of the object 12 to be removed. The object to be removed 12 is divided into a large object to be removed 12A that cannot pass through the filter hole 11 and a small object to be removed 12B that can pass through the filter hole 11. In the figure, a small object 12B that can be passed is indicated by a black circle.

The support filter membrane that can be employed here is:
In principle, both organic polymer type and ceramic type can be adopted. However, here, the average pore diameter is 0.25.
A polyolefin polymer film having a thickness of 0.1 μm and a thickness of 0.1 mm was employed.

[0086] Above the supporting filter membrane 10 in Fig. 5, there is drainage mixed with the substance to be removed, and below the supporting filter membrane 10, filtered water filtered by the supporting filter membrane 10 is generated. In order to drain the wastewater in the direction of the arrow and to filter the wastewater using the supporting filter membrane 10, the water is naturally dropped or pressurized and moves downward in the figure. Also, drainage is sucked from the side where the filtered water is. The support filter membrane 10 is arranged horizontally, but is actually arranged vertically as shown in FIG.

As described above, as a result of pressurizing or sucking the wastewater through the filter membrane, the wastewater passes through the supporting filter membrane 10. At this time, the large removal object 12A that cannot pass through the filter hole 11 is captured on the surface of the support filter film 10.

The objects to be removed are located at random in the wastewater in which the supporting filter film 10 is soaked, and large to small objects move to the filter hole 11 at random. Then, the large object to be removed 12A captured at random becomes the first layer of the multilayer filter film 13, and this layer forms a filter hole smaller than the filter hole 11, and the large object to be removed 12 through the small filter hole.
Small object to be removed 12B is captured from A. At this time, the object to be removed generated by machining such as grinding, polishing, or pulverization is distributed in a certain range in size (particle diameter), and since the shape of each object to be removed is different, There are gaps of various shapes between the objects to be removed, water moves through the gaps as passages, and finally the wastewater is filtered. This is very similar to a well-drained beach.

The laminated filter film 13 grows gradually while randomly capturing the small object to be removed 12B from the large object to be removed 12A, and traps the small object to be removed 12B while securing a water (fluid) passage. Looks like FIG. 6 shows this state. Moreover, the laminated filter film 13
The object to be removed can easily move like sand just by remaining in a layer, so that bubbles can be passed near the layer,
By giving water flow, giving sound waves or ultrasonic waves, giving mechanical vibrations, and even rubbing with a squeegee, etc.
The surface layer of the multilayer filter membrane 13 can be easily moved to the drain side. Even if the filtering ability of the multilayer filter membrane 13 is reduced, the structure that is separated individually like sand is a factor that can easily restore the ability by applying an external force to the multilayer filter membrane 13. In other words, the cause of the decrease in the filter capacity is mainly clogging, and the object to be removed on the surface layer of the laminated filter film 13 causing the clogging may be moved into the fluid again. As a result, clogging is repeatedly eliminated to maintain the filtration ability.

However, when the support filter film 10 is newly attached, the layer of the object to be removed 12 (laminated filter film 13) is not formed on the surface of the support filter film 10. Since only a thin layer of the filter film 13 is formed, a small object to be removed 12 </ b> B passes through the filter hole 11. At this time, the filtered water is circulated again to the side where the wastewater is stored, and waits until it is confirmed that the small removal object 12B is captured by the second filter membrane 13. After the confirmation, small objects to be removed such as the small object 12B that has passed have been captured one after another, and the wastewater is filtered with a predetermined cleanliness.

It is easy to confirm if an object detecting means such as the optical sensor 67 shown in FIG. 2 is attached so that the mixing ratio of the object can be inspected.

If small removal objects 12B remain in the filtered water, instead of returning the filtered water, it is transferred to another tank, and the small removal objects 12B and the removal objects 1B are removed.
Wait until it is confirmed that an object having the same size as 2B has been captured.
Small removal objects such as B are successively captured, and the wastewater is filtered with a predetermined degree of cleanliness, so that the filtered water can be reused. The wastewater stored in the upper layer of the multilayer filter membrane 13 is gradually concentrated.

The graph shown in FIG. 7 shows the particle size distribution of the object to be removed. As an example, the graph shows the particle size distribution of cutting chips generated during dicing of a Si wafer. It is distributed in the range of approximately 0.1 μm to 200 μm. still,
Since the particle size distribution measuring device could not detect particles smaller than 0.1 μm, the distribution of cutting chips smaller than 0.1 μm is not shown. However, in reality, something smaller is included. According to experiments, it has been found that when the wastewater mixed with the cuttings is filtered, the cuttings are formed on the first filter film 10 and capture up to 0.1 μm or less. In addition, the actual dicing debris includes, in addition to Si, an insulating film made of a Si oxide film, a Si nitride film, or the like, and a metal material made of Al, Cu, W, or the like.

For example, if it is intended to remove cutting chips up to 0.1 μm, it is a general idea to employ a support filter having holes smaller than this size. However, it can be seen from the above description that, while the large and small particle sizes are distributed, cutting chips of 0.1 μm or less can be captured even if a filter hole having a size between them is adopted.

Conversely, the peak of the particle size of the object to be removed is 0.1 μm.
If the distribution is within a very narrow range of several μm, the supporting filter and the laminated filter will be clogged immediately. As can be seen from FIG. 7, the dicing debris of Si, which is an object to be removed, has two peaks having a large particle size and a small particle size, and is 〜200 μm.
, The filtering ability is improved. Observation with an electron microscope or the like shows that the shape of the object to be removed is various. That is, since there are at least two peaks in the particle diameter and the shapes of the objects to be removed are various, various gaps are formed between the objects to be removed, and the passages serve as filtrate water passages. Is considered to have been realized. As described above, the surface of the support filter membrane 10 has a thickness of 0.1 μm or less to 200 μm.
m having a particle size distribution of up to m
It can be seen that when formed as 3, even an object to be removed of 0.1 μm or less can be removed. Further, the maximum particle size is not limited to 200 μm, but may be larger. For example, ~ 500μ
m, filtration can be performed even on objects to be removed having a size of 500 μm or more. In addition, since it is possible to remove an object having a size of 0.1 μm or less, it is understood that fine particles such as abrasive grains of CMP can be filtered. That is, the solid filter having the particle size distribution as shown in FIG.
Forming No. 3 and immersing the filtration device in the CMP wastewater enables filtration. Next, the filtering device 35 immersed in the drainage tank 50 will be described with reference to FIGS.

Reference numeral 30 shown in FIG. 8A is a frame shaped like a picture frame, and a support filter film 31,
32 are adhered and fixed. Then, a pipe 34 is sucked into an inner space 33 surrounded by the frame 30 and the support filter membranes 31 and 32, so that the support filter membrane,
Filtration water generated by the laminated filter is generated. And the pipe 34 sealed and attached to the frame 30
The filtered water is taken off via Of course, the supporting filter membranes 31, 32 and the frame 30 are completely sealed so that the drainage does not enter the space 33 from other than the filter membrane.

Since the support filter films 31 and 32 in FIG. 8A are thin resin films, they may warp inward when sucked and may be broken. Therefore, it is necessary to form a lot of this space in order to make this space as small as possible and to increase the filtering capacity. This is shown in FIG. 8b. In the figure, only nine spaces 33 are shown,
In fact, many are formed. The support filter membranes 31 and 32 actually employed are polyolefin-based polymer membranes having a thickness of about 0.1 mm. As shown in the figure, a thin filter membrane is formed in a bag shape, and is indicated by FT in the drawing. Was. The frame 3 in which the pipe 34 is integrated in the bag-shaped filter FT
0 is inserted, and the frame 30 and the filter FT are attached to each other. Reference numeral RG is a pressing means for pressing the frame to which the filter film FT is attached from both sides. The filter film FT is exposed from the opening OP of the holding means.

FIG. 8C shows a filter device 35 having a cylindrical shape. The frame attached to the pipe 34 is cylindrical, and has openings OP1 and OP2 on the side surface. Since the side surfaces corresponding to the openings OP1 and OP2 have been removed, the support filter film 31 is provided between the openings.
Will be provided. Then, the supporting filter films 31 and 32 are bonded to the side surfaces.

The filtering device 35 shown in FIG. 8B will be described in detail with reference to FIG. First, a portion 30a corresponding to the frame 30 in FIG. 8B will be described with reference to FIG. 9B.

Reference numeral 30a has a shape like a corrugated cardboard as seen. 0.2mm thin resin sheet SH
T1 and SHT2 overlap each other, and a plurality of sections SC are provided in the vertical direction between them.
2, a space 33 is provided surrounded by the section SC.
The cross section of the space 33 is a rectangle having a length of 3 mm and a width of 4 mm. In other words, the straw 33 has such a shape that a number of straws having the rectangular cross section are arranged and integrated. Reference numeral 30a is hereinafter referred to as a spacer because the filter films FT on both sides are maintained at a constant interval.

A hole H having a diameter of 1 mm is formed on the surface of the thin resin sheets SHT1 and SHT2 constituting the spacer 30a.
L is opened a lot, and the filter film FT is bonded to the surface. Therefore, the filtered water filtered by the filter membrane FT passes through the hole HL and the space 33, and finally exits from the pipe 34.

Further, both surfaces SHT1, SH of the spacer 30a are
T2 has a portion where the hole HL is not formed, and when the supporting filter film FT1 is directly attached thereto, the hole H
Support filter membrane F corresponding to the portion where L is not formed
In T1, since there is no filtration function and the drainage does not pass, a portion where the object to be removed is not captured occurs. In order to prevent this phenomenon, at least two filter films FT are attached. The filter film FT1 on the top surface is a supporting filter film that captures an object to be removed. A filter film having holes larger than the holes of the filter film FT1 is provided from the filter film FT1 toward the surface SHT1 of the spacer 30a. Here, one filter film FT2 is attached. Therefore, even in a portion where the hole HL of the spacer 30a is not formed, since the filter film FT2 is provided therebetween, the entire surface of the filter film FT1 has a filtering function, and an object to be removed is present on the entire surface of the filter film FT1. Captured,
The laminated filter film is formed on the front and back surfaces SH1 and SH2. Also, for the convenience of the drawing, the filter film FT
Although FT2 is represented as a rectangular sheet, it is actually formed in a bag shape as shown in FIG. 8B.

Next, bag-shaped filter membranes FT1, FT2,
How the spacer 30a and the holding means RG are attached will be described with reference to FIGS. 9A, 9C, and 9D.

FIG. 9A is a completed view, and FIG. 9C is FIG. 9A.
As indicated by line A-A of FIG.
FIG. 9D is a view cut in the extending direction (vertical direction) of FIG.
Is a cross-sectional view when the filtration device 35 is cut in the horizontal direction as indicated by the line BB.

As can be seen from FIGS. 9a, 9c and 9d, the spacer 30a inserted in the bag-like filter film FT is used.
The four sides including the filter film FT are sandwiched by the holding means RG. Then, the three sides and the remaining one side bound in a bag shape are fixed by the adhesive AD1 applied to the holding means RG. A space SP is formed between the remaining one side (opening of the bag) and the holding means RG, and the filtered water generated in the space 33 is sucked into the pipe 34 via the space SP. Further, the adhesive AD2 is provided over the entire periphery of the opening OP of the holding member RG, is completely sealed, and has a structure in which fluid cannot enter from anything other than the filter.

Thus, the space 33 and the pipe 34 are in communication with each other. When the pipe 34 is sucked, the fluid passes through the hole of the filter membrane FT and the hole HL of the spacer 30a toward the space 33, and from the space 33 to the pipe 34. The structure is such that filtered water can be transported to the outside via the. This filtering device 35
FIG. 10 conceptually shows the operation of FIG. Here, if the pipe 34 side is sucked by a pump or the like, water flows and is filtered as indicated by an arrow without hatching.

First, the object to be removed in the waste water is transferred to the support filter membrane 3.
After capturing at 1 and 32 and forming the laminated filter film 36,
A description will be given of a method of filtering.

9 is immersed in a tank in which the fluid containing the object 12 is stored, and the fluid is sucked through the pipe. Then, the fluid passes as indicated by the white arrow. The small object to be removed 12B passes, but the large object to be removed 12A is captured by the supporting filter films 31 and 32, and the small object to be removed 12B is gradually captured. Then, when the amount of the substance to be removed in the filtered water is lower than a predetermined mixing ratio, the laminated filter membrane 3
6 will be completed. And after this, the filtration device 35
If filtration is performed using, filtration becomes possible. Further, the filtering device 35 may be immersed in another wastewater and filtered.

The filter device 35 is immersed in a drainage tank containing wastewater of dicing debris (removed material), and is filtered with a predetermined accuracy as it is filtered, and the wastewater in the drainage tank becomes highly concentrated with time. You will see that it goes.

At this time, since the object to be removed 12 is gathered in the laminated filter film 36, an external force is applied to the laminated filter film 36 to remove the laminated filter film 36 or remove the surface layer of the laminated filter 36. Or you can. Also, by applying an external force, the laminated filter film 3 can be easily formed.
The object to be removed can be separated from 6 and can be moved to the drain 37.

This removal or separation can be easily realized by a bubble rising force, water flow, sound wave, ultrasonic vibration, mechanical vibration, rubbing the surface using a squeegee, or a stirrer. Further, the filtering device 35 itself to be immersed may be configured to be movable in the drainage, and a water flow may be generated on the surface layer of the laminated filter film 36 to remove the laminated filter 36 and the objects 14 and 15 to be removed. For example, in FIG.
May be moved to the left and right as indicated by arrow Y with the bottom surface as a fulcrum. In this case, since the filtration device itself is movable, a water flow is generated, and the surface layer of the laminated filter 36 can be removed. When the bubble generating device 54 shown in FIG. 2 is also used, if the movable structure is adopted, the bubbles can reach the entire surface of the filtration surface, and the removed matter can be efficiently moved to the drainage side.

If the cylindrical filtering device shown in FIG. 8C is employed, the filtering device itself can be rotated around the center line CL, and the drainage resistance can be reduced. Due to this rotation, a water flow is generated on the filter membrane surface, and the object to be removed on the surface layer of the second filter membrane can be moved to the drainage side,
The filtration ability can be maintained.

FIG. 10 shows an example in which the rising of bubbles is used as a method of removing the laminated filter film. The bubbles rise in the direction of the hatched arrow, and the rising force of the bubbles and the burst of the bubbles directly apply external force to the object or solid to be removed, and the water flow generated by the rising force of the bubbles and the burst of the bubbles is removed. Apply external force to objects and solids. Then, the filtering force of the laminated filter membrane 36 is constantly refreshed by this external force, and maintains a substantially constant value.

Even if clogging occurs in the multilayer filter membrane 36 and its filtration ability is reduced, an external force for moving the object 12 constituting the multilayer filter membrane 36 is applied as in the case of the air bubbles, thereby providing a multilayer filter membrane. Removal object 1 constituting film 36
2 can be moved to the drain side, and the filtration capacity can be maintained for a long time.

This seems to be that the thickness of the multilayer filter is made substantially constant by applying an external force. Also, as if each object to be removed has a stopper at the entrance of the filtered water,
The plug is detached by an external force, filtered water infiltrates from the detached portion, and when the plug is formed, the removal by the external force is repeated. This has the merit that the filtration ability can be always maintained by adjusting the size of the bubble, the amount thereof, and the time during which the bubble is applied.

As long as the filtration ability can be maintained, an external force may be constantly applied or may be applied intermittently.

As can be said in all the embodiments, the laminated filter membrane needs to be completely immersed in the waste water. This is because the laminated filter film is dried, peeled or collapsed when exposed to air for a long time. Also, if a small number of the laminated filters are in contact with the air, the laminated filter membrane sucks the air, so that the filtering ability is reduced.

As described above, in view of the principle of the present invention, as long as the laminated filter film 36 is formed on the support filter films 31 and 32, the support filter films 31 and 32 may be formed of a ceramic polymer sheet. However, it may be a suction type or a pressure type. However, when actually adopted, the support filter membranes 31 and 32 are preferably polymer membranes, and more preferably a suction type. The reason is described below.

First, when a sheet-like ceramic filter is produced, the cost is considerably increased. When a crack is generated, a leak is generated, and filtration cannot be performed. In the case of a pressurized type, it is necessary to pressurize the wastewater. For example, taking the tank 50 of FIG. 2 as an example, to apply pressure, the upper part of the tank must be closed rather than open. However, if it is a closed type, it is difficult to generate air bubbles. On the other hand, as the polymer film, sheets and bag-shaped filters of various sizes are available at low cost. In addition, cracks do not occur because of flexibility, and it is easy to form irregularities on the sheet. By forming the unevenness, the laminated filter film bites into the sheet, and separation in drainage can be suppressed. Moreover, in the case of the suction type, the tank may be left open.

When the pressure type is used, it is difficult to form a laminated filter film. In FIG. 10, assuming that the pressure in the space 33 is 1, it is necessary to apply one or more pressures to the drainage. Therefore, it is considered that a load is applied to the filter membrane, and the trapped object is fixed at a high pressure, so that the object is difficult to move.

Therefore, when the filtration device 35 having the laminated filter film 36 formed of the material to be removed is immersed in the drainage tank 50 and filtered, the filtration ability can be constantly maintained.
The wastewater 52 of 0 can increase the concentration of the wastewater to a predetermined concentration in a fixed filtration period.

Although the object to be removed has been described with reference to silicon waste generated from a Si wafer, the object to be removed is at least one of elements of groups 2a to 7a and 2b to 7b in the periodic table. Most of these inorganic solids can be removed by employing the present invention. In addition, the present invention can capture an object to be removed of 0.1 μm or less.
It was determined that the removal objects distributed in a narrow range of about μm could also be captured.

That is, a film in which an object to be removed composed of dicing dust is formed in a layered form is utilized as the laminated filter film 36,
The filter on which the laminated filter film 36 is formed is subjected to CMP.
Was immersed in the wastewater and filtration was attempted.

FIG. 11 shows this. Reference numeral 14 shown by a white circle is fine abrasive grains, and reference numeral 15 shown by a double circle is a polished (ground) object generated by CMP, and these are objects to be removed. In addition, according to the definitions of the object to be removed and the solid matter, the names of the object to be removed 12 shown in FIG. 10 are changed to a large solid matter 16A and a small solid matter 16B.

For example, the material of abrasive grains for CMP of an interlayer insulating film made of Si oxide is made of Si oxide, and is generally called silica. Fig. 12
As in a and b, the minimum particle diameter was about 0.076 μm, and the maximum particle diameter was 0.34 μm. The largest particle is an aggregated particle formed by collecting a plurality of particles therein. The average particle size is about 0.1448 μm, and the average
The distribution has a peak at 0.15 μm. In addition, KOH or NH3 is generally used as a slurry modifier. Also, PH is between about 10 and 11. The operation concept of the filtering device 35 will be described with reference to FIG.

The filtering device 35 is immersed in a tank in which a fluid containing the solid 16 is stored.
It is sucked through the pipe 34. And a small solid 1
6B passes, but large solids 16A are captured by the supporting filter membranes 31, 32 and gradually become smaller solids 16B.
Will also be captured. When the solid content becomes lower than the predetermined mixing ratio, the laminated filter film 36 is completed.

Subsequently, as shown in FIG. 11, the filtration device 35 on which the laminated filter film 36 is formed is moved to the object 1 to be removed.
Put into drainage 37 containing 4 and 15. And pipe 3
By sucking 4, the objects to be removed 14 and 15 are captured by the laminated filter film 36. At this time, the laminated filter film 36
Indicates that since the solids 16 are aggregated,
By applying an external force to 6, the multilayer filter film 36 can be removed, or the surface layer of the multilayer filter 36 can be removed. Further, since the abrasive grains 14 and the object to be polished (ground object) 15 which are the objects to be removed are also aggregates of individuals, they can be easily separated from the laminated filter film 36 by applying an external force and moved to the drainage 37. Can be done.

As described above, this removal or separation can be easily realized by rubbing the surface with a bubble rising force, water flow, sound wave, ultrasonic vibration, mechanical vibration, a squeegee, or a stirrer.

FIG. 11 shows an example in which the rise of air bubbles is utilized as a method of removing the laminated filter film. The bubbles rise in the direction of the hatched arrow, and the rising force of the bubbles and the burst of the bubbles directly apply external force to the object or solid to be removed, and the water flow generated by the rising force of the bubbles and the burst of the bubbles is removed. Apply external force to objects and solids. Then, the filtering force of the laminated filter membrane 36 is constantly refreshed by this external force, and maintains a substantially constant value.

That is, even if the filter capacity is reduced due to clogging of the laminated filter membrane 36, as in the case of the bubbles,
The solid matter 16 and the object 1 to be removed constituting the laminated filter film 36
By applying an external force to move the layers 4 and 15, the solids 16 and the objects to be removed 14 and 15 constituting the laminated filter membrane 36 can be moved to the drainage side, and the filtering ability can be maintained for a long time.

This is presumably because the thickness of the multilayer filter is made substantially constant by applying an external force. Also, as if each object to be removed has a stopper at the entrance of the filtered water,
The plug is detached by an external force, filtered water infiltrates from the detached portion, and when the plug is formed, the removal by the external force is repeated. This has the merit that the filtration ability can be always maintained by adjusting the size of the bubble, the amount thereof, and the time during which the bubble is applied.

As long as the filtration ability can be maintained, an external force may be constantly applied or may be applied intermittently.

As can be said in all the embodiments, the filter membrane needs to be completely immersed in the waste water. This is because the laminated filter film is dried, peeled or collapsed when exposed to air for a long time. Also, if any filter is in contact with the air, the filter membrane sucks the air, so that the filtering ability is reduced.

For example, CMP uses a slurry containing a chemical and abrasive particles of 0.1 μm or less. Then, water is flushed at the time of polishing, and wastewater having a concentration lower than that of the slurry is discharged. However, as the concentration of the discharged stock solution increases as it is filtered, viscosity also comes out at the same time. And when the interval between the filtration devices is narrow and viscosity comes out,
Air bubbles are less likely to enter the space between the filtration devices, and the air bubbles do not apply any external force to solids or objects to be removed. In addition, when the material to be removed is very fine, the filtration ability is rapidly reduced. For this reason, when the concentration reaches a predetermined value, it is transferred to another filtering device 68 as shown in FIG.

Here, the solution is filtered through the filter FTb, and the high-concentration undiluted solution is sucked up to some extent. On the other hand, the transfer of the undiluted solution to the filtration device FD lowers the drainage level of the drainage tank 50, but the pipe 51 supplies low-concentration drainage. And when the concentration of the wastewater becomes thin and the wastewater completely soaks the filter,
If the filter is set to start again, the air bubbles enter between the filtration devices and give an external force to the solid matter.

For example, when the concentration of the drain tank 50 containing the substance to be removed reaches a predetermined concentration, the coagulation and sedimentation is not performed and the collection device 6
8 (FD). Removed object 1
Since Nos. 4 and 15 are not reacted with the chemicals used for coagulation and sedimentation, they are relatively high in purity and can be reused in various fields.

FIG. 12 is data showing that the CMP wastewater is filtered and the abrasive grains are captured. In the experiment, the undiluted solution of the above-mentioned slurry was purified 50 times, 500 times, 50 times with pure water.
It was diluted to 00 times and prepared as a test solution. As described in the conventional example, in these three types of test liquids, since the wafer is washed with pure water in the CMP process, the drainage is 50 times or more.
It was prepared assuming that it would be about 5000 times. Examining the light transmittance of these three types of test liquids, a 50-fold test liquid is 22.5%, a 500-fold test liquid is 86.5%,
The 5000 times test solution is 98.3%. When these three types of test liquids are filtered by a filtration device provided with the second filter membrane 36, the transmittance after filtration is 99.
8 percent. The transmittance data of 50-fold dilution does not appear in the drawing because its value is small.

From the above results, it was found that the filter having the multilayer filter film formed of the solids 16A and 16B was
The material to be removed from the filter is filtered to obtain a transmittance of 99.
It turned out that it can filter to about 8%.

A solid having a particle size distribution as shown in FIG. 7 is formed by polishing, grinding, pulverizing, etc., or a solid in the natural world is collected.
It was found that by forming this as a layered film, a laminated filter capable of capturing a fluid of 0.1 μm or less could be formed. As shown in the figure, it is preferable that the ratio of the large solid is larger than the ratio of the small solid. As described above, the fine particles can be captured by the laminated filter, and the wastewater is generated by differentiating the material composition of the object to be removed, by the specific impurities in the object to be removed, and in the CMP, by the abrasive grains or the metal material to be polished. Then, the object to be removed can be collected by sorting with a collection device, and the subsequent processing can be easily performed in the case of reuse or disposal.

[0140] In particular, an object to be removed containing impurities whose environmental standards are very strict is separated from other objects to be removed and is discharged to a wastewater, and the wastewater is concentrated in a wastewater tank. Wastewater is separated by a recovery device. Therefore, a specific object to be removed can be selectively recovered, and efficient recovery can be achieved.

[0141]

As is evident from the above description, it is possible to selectively collect materials to be removed by material composition and specific impurities in the material to be removed, and to reuse the material to be removed after being collected. Processing or disposal is facilitated. Particularly, materials or impurities having extremely strict environmental standards are sorted out, and most of them can be recovered.

The laminated filter made of the object to be removed or the solid matter can be formed with a very simple structure.
Since fine particles having a size of μm or less can be captured, most of the objects to be removed can be recovered, and the objects and fluids can be reused because no chemical is used. Therefore, industrial waste can be reduced as much as possible,
Environmentally friendly filtration can be realized.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining separation and collection according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a method of recovering an object to be removed from a fluid according to an embodiment of the present invention.

FIG. 3 is a diagram illustrating a fluid removal object recovery apparatus and a recovery method according to the present invention.

FIG. 4 is a diagram illustrating a specific configuration of the collection device of FIG. 2;

FIG. 5 is a diagram illustrating a method for forming a filter made of an object to be removed according to the embodiment of the present invention.

FIG. 6 is a diagram illustrating a method for forming a filter made of an object to be removed according to the embodiment of the present invention.

FIG. 7 is a diagram illustrating a particle size distribution of silicon dust in wastewater generated during dicing.

FIG. 8 is a diagram illustrating a filtration device employed in the present invention.

FIG. 9 is a diagram illustrating a filtration device employed in the present invention.

FIG. 10 is a diagram illustrating a filtering operation.

FIG. 11 is a diagram illustrating a filtering operation.

FIG. 12 is a diagram illustrating the distribution of fine particles mixed into wastewater generated from CMP, the light transmittance of the wastewater, and the light transmittance when the wastewater is filtered.

FIG. 13 is a schematic diagram of a dicing apparatus.

FIG. 14 is a schematic diagram of a back grinding device.

FIG. 15 is a diagram illustrating a conventional filtration system.

FIG. 16 is a diagram illustrating a CMP apparatus.

[Explanation of symbols]

 32 Support Filter 35 Filtration Device 36 Stacked Filter 50 Drain Tank 52 Drain 53 Filter Device 54 Bubble Generator 67 Sensor 68 Collection Device 72 First Storage Tank 73 Second Storage Tank 75 Collected Material 76 Container

Claims (9)

[Claims] 1. A fluid mixed with an object to be removed into which an impurity has been introduced is substantially distinguished by the material of the impurity, and a fluid filtered for each fluid distinguished by the material of the impurity is taken out and left. A method for collecting a fluid to be removed, the method comprising recovering the material to be removed for each of the impurities. 2. A first fluid containing a first object having a first impurity mixed therein is introduced into a first tank, and a second fluid is introduced into a second tank.
A second fluid mixed with a second object to be removed having impurities is put therein, and the filtered fluid is taken out from the first tank and the second tank to increase the mixing ratio of the object to be removed, respectively. The first fluid and the second fluid having an increased mixing ratio of the substance are transferred to a first recovery tank and a second recovery tank, respectively, and provided in the first tank and the second recovery tank. The fluid is removed by the fluid removing means, and the first object and the second object remaining in the first recovery device and the second recovery device are separately collected. A method for recovering an object to be removed from a fluid. 3. The first tank, wherein a part of the first fluid is filtered by the filter comprising at least a part of the first object to be removed contained in the first fluid. In the second tank, a part of the second fluid is removed from the second tank by a filter including at least a part of the second object to be removed contained in the second fluid. The method according to claim 2, wherein the first fluid and the second fluid have an increased mixing ratio of the object to be removed. 4. In the first tank, a part of the first fluid is taken out of the first tank with a filter made of the first object to be removed contained in the first fluid, In the second tank, a part of the second fluid is taken out of the second tank with a filter made of the second substance to be removed contained in the second fluid, and the mixing rate of the substance to be removed is increased. The method according to claim 2, wherein the first fluid and the second fluid are used as the first fluid and the second fluid. 5. The first fluid in the first tank is circulated through a first support filter, and a first multilayer filter made of the first object to be removed is provided on the surface of the first support filter. Forming, removing a part of the first fluid from the first tank by the first laminated filter to obtain a first fluid having a higher mixing ratio of the first substance to be removed; Circulating the second fluid in the tank through the second support filter to form a second multilayer filter made of the second object to be removed on the surface of the second support filter; The fluid according to claim 3, wherein a part of the second fluid is taken out of the second tank by a filter, and is used as a second fluid having an increased mixing ratio of the second substance to be removed. Removal method. 6. In the first tank, a part of the first fluid is taken out of the first tank with a filter made of a solid substance different from the first substance to be removed contained in the first fluid, In the second tank, a part of the second fluid is taken out of the second tank with a filter made of a solid substance different from the second object to be removed contained in the second fluid, and the object to be removed is removed. The first fluid and the second fluid having an increased mixing ratio of the first fluid and the second fluid having a higher mixing ratio of the object to be removed. The first and second recovery tanks are removed from the first recovery device and the second recovery device, respectively, by removing the fluid by the fluid removal means provided in the first and second recovery tanks. A fluid to be collected separately from the first material to be removed and the second material to be removed; Removed substance recovery method. 7. A first laminated filter made of a solid material different from the first object to be removed formed on the surface of a first support filter and immersed in a first fluid of the first tank, A part of the first fluid is taken out of the first tank by the first laminated filter and is taken as a first fluid having an increased mixing ratio of the first substance to be removed, A second laminated filter made of a solid material different from the second object to be removed formed on the surface of the second support filter is immersed in the second fluid, and the second fluid is filtered by the second laminated filter. 7. The method according to claim 6, wherein a part of the fluid is taken out of the second tank and used as a second fluid having an increased mixing ratio of the second material. 8. The apparatus according to claim 5, wherein the first multilayer filter includes first objects to be removed having different sizes or first solid materials having different sizes. 3. The method for recovering an object to be removed of a fluid according to 1. 9. The first object to be removed includes particles of different sizes, wherein the size of the pores of the first support filter is larger than the size of the smallest particles and the size of the largest particles. The method for recovering an object to be removed of a fluid according to claim 5, wherein the method is smaller than the above.