Patent Application
20230276931
The present invention relates to a cleaning sponge roller.
In a manufacturing step of aluminum hard disks, glass disks, wafers, photomasks, liquid crystal glass substrates, or the like, high-precision polishing, a so-called polishing process, using various abrasive grains such as silicon oxide, alumina, and ceria is performed in order to finish their surfaces with extremely high precision. Since abrasive grains and polishing dust adhere to the surface of a polished object after the polishing process, it is necessary to wash the surface thoroughly after the polishing process in order to remove those things.
As a cleaning method after the polishing process, there are methods using ultrasonic cleaning and jet water flow. In addition, scrub cleaning using a sponge body made of an elastic porous material (for example, a polyvinyl acetal-based porous material) is widely used in order to obtain a high cleaning effect and to reduce damage to the substrate. As a cleaning liquid, not only normal DI water but also various chemicals each suitable for a certain substrate such as acids, alkalis, and solvents are used. For example, known cleaning liquids for silicon wafers include a mixture liquid of ammonia water and hydrogen peroxide water, dilute hydrofluoric acid, a mixture liquid of hydrochloric acid and hydrogen peroxide water, and the like.
There are various shapes of sponge bodies of elastic porous materials. Among them, a cylindrical brush-roller-shaped sponge body having a large number of nodules on its outer circumferential surface is preferably used for scrub cleaning (cleaning step). While the sponge body is being rotated, the tops of the nodules are continuously brought into contact with the cleaning target surface of an object to be cleaned, thereby obtaining a good cleaning effect. Since the object to be cleaned is brought into contact with only the nodules of the sponge body, the above sponge body has advantages over a flat sponge body without having nodules in that damage to an object to be cleaned is small due to low friction or contaminants can easily pass together with the cleaning liquid between the nodules and be removed from the object to be cleaned.
In the cleaning step, a cleaning device dedicated to each substrate is usually used. A cleaning sponge roller is composed of a sponge body and a core. The core is inserted through an inner diameter portion of the sponge body, and fixedly supports the inner circumferential surface of the sponge body. The cleaning sponge roller is attached to the cleaning device with both ends of the core connected to rotation-driving sections of the cleaning device, and the sponge body is rotated together with the core while the sponge body and the object to be cleaned (in the case of a sponge body having nodules, the nodules and the object to be cleaned) are in contact with each other.
There is a device that supplies a cleaning liquid to an object to be cleaned or a sponge body from its upper side or lateral side with a nozzle or the like. Instead, in practice, the cleaning liquid is also supplied from the inside of the core to the inside of the sponge body in order to improve the cleaning performance.
As a technique for supplying a cleaning liquid from the inside of the core to the inside (inner circumferential surface) of the sponge body, known is a technique in which a hollow cylindrical hard core having an inner hole extending in an axial direction is provided with multiple small holes penetrating from the inner hole to an outer circumferential surface of the core. One end portion of the core is supported in a relative rotation-disabled manner by a rotation-driving side shaft support of the cleaning device, and the other end portion thereof is supported in a relative rotation-disabled manner by a rotation-driven side shaft support of the cleaning device. One end of the inner hole is closed, whereas the other end thereof is opened. In the other end portion of the core supported by the rotation-driven side shaft support, the inner hole and a cleaning liquid supply channel of the cleaning device communicate with each other. The cleaning liquid is introduced into the inner hole of the core from the cleaning liquid supply channel, supplied from the inner hole to the inner circumferential surface of the sponge body through the multiple small holes, and flows out to the outer surface of the sponge body through continuous pores of the sponge body.
Patent Literature 1: International Publication No. WO2009/147747
Patent Literature 2: Japanese Patent No. 4965253
Patent Literature 3: Japanese Patent No. 5032497
Patent Literature 4: Japanese Patent No. 6027101
When the cleaning sponge roller is attached to the cleaning device and used for the first time, break-in step for improving the cleanliness of the sponge body itself is performed as a preparatory step before the actual scrub cleaning is performed. Specifically, after the sponge body is attached to the cleaning device, scrub cleaning is performed using dummy wafers. In the break-in step, for example, a wafer for monitoring is used in the middle, the number of actual defects on the wafer is counted, and the break-in is completed when it is confirmed that the number of defects falls below a certain number. Instead, the number of wafers to be processed (specified number of wafers) required until the number of defects on the wafer is sufficiently decreased is checked in advance, and the break-in is completed when the cleaning of the specified number of wafers is completed.
However, in the case of a core provided with multiple small holes penetrating from the inner hole to the outer circumferential surface of the core, the places and the number of the outlets (small holes) of water flowing from the core to the sponge body are fixed. For this reason, even after the break-in step is completed, some areas having not permeated by water remain in the sponge body. In this case, there is a possibility that, in subsequent use, water flowing through the not-permeated areas may cause wafer contamination. In short, since the places through which the water is discharged from the core are limited to the particular positions (the positions of the small holes), there is a possibility that the state inside the sponge body may have variation.
In addition, the above conventional core in which the places and the number of the outlets (small holes) of water flowing to the sponge body are fixed has a possibility that even during scrub cleaning after the break-in is completed, a volume of permeation through the sponge body may vary (the volume of permeation may be uneven) from place to place. When the volume of permeation is uneven, the concentration of a chemical solution directly supplied from the sponge body onto a wafer is also uneven, which may cause a failure to uniformly clean the entire region of the wafer.
Therefore, the present invention has an object to provide a cleaning sponge roller capable of reducing variation in the volume of permeation.
To achieve the above object, a cleaning sponge roller of the present invention includes a cylindrical sponge body and a shaft-shaped core. The sponge body is formed of a porous material having continuous pores and having elasticity in a wet state. The core is inserted through an inner diameter portion of the sponge body, and fixedly supports an inner circumferential surface of the sponge body. The core is formed of a porous sintered compact having continuous pores.
In the above structure, since the core is formed of the porous sintered compact having the continuous pores, the continuous pores of the sintered compact serve as channels (permeation channels) for water (for example, cleaning water) flowing from the inside to the outer circumferential surface of the core (sintered compact). For this reason, the permeation channels can be arranged more evenly and densely than in a case where holes for water passing (water passing holes) are formed in a core not having continuous pores, so that variation in the volume of permeation through the sponge body can be reduced.
The above core is preferably formed of an organic sintered compact (resin sintered compact or sintered compact plastic). In the case of organic sintered compacts, there is no concern about the influence of metal elution on cleaning unlike metal sintered compacts (sintered metals), and workability and rigidity are superior to those of inorganic sintered compacts (ceramics).
The shape of the sintered compact may be any of a pillar shape and a tubular shape, but is preferably a tubular shape in order to reduce a pressure loss during water passing. It should be noted that the cross-sectional shape in either of the pillar shape and the tubular shape is not limited to a circular shape, and may be any other shape (for example, a polygonal shape or the like).
In the sintered compact, an average pore diameter is preferably 5 μm to 800 μm and a porosity is preferably 30% to 50%. This is because too small an average pore diameter and too low a porosity may result in an increase in the pressure loss during water passing, whereas too large an average pore diameter and too high a porosity may result in a failure to secure a sufficient strength.
The sponge body may be fixed to the core by entering the continuous pores of the sintered compact and being integrated with the sintered compact. Since the inner diameter side of the sponge body enters the fine continuous pores of the sintered compact and is integrated with the core while continuing in a densely intricate state, the sponge body can be fixed to the core more strongly than in the case where water passing holes are formed in a core not having continuous pores and a sponge body enters the water passing holes.
Moreover, in the case where a tubular core is used, it is preferable that a space (water passing space) continuously extending in an axial direction be secured in the inner diameter portion of the core instead of filling the entire region of the inner diameter portion of the core with the sponge body in order to suppress an increase in pressure loss during water passing.
According to the present invention, it is possible to reduce variation in the volume of permeation.
A cleaning sponge roller (hereinafter referred to as the sponge roller) 1 according to an embodiment of the present invention will be described in reference to
As illustrated in
The sponge body 3 has multiple nodules 5 protruding from an outer circumferential surface 4 at an approximately uniform density. Each nodule 5 has a circular columnar shape and integrally protrudes to a top portion (tip end portion) from a base end portion on the outer circumferential surface 4 of the sponge body 3. The shape of the nodule 5 is not limited to the circular columnar shape and may be any other shape. Moreover, the outer circumferential surface 4 of the sponge body 3 may be a smooth curved surface provided with no nodules 5.
The sponge body 3 is formed of, for example, a polyvinyl acetal-based porous material (PVAt-based porous material) having fine continuous pores and having elasticity in a water-containing state. The PVAt-based porous material is hardened in a dry state and is softened in a wet state. In addition, the PVAt-based porous material is excellent in water absorption and water retention, exhibits favorable flexibility and moderate impact resilience in a wet state, and is also excellent in abrasion resistance.
The core 2 is inserted through an inner diameter portion of the sponge body 3 and fixedly supports an inner circumferential surface of the sponge body 3. Although the core 2 of the present embodiment has a cylindrical shape as illustrated in
The core 2 is formed of a sintered compact having continuous pores.
The sponge body 3 of the present embodiment is fixed to the core 2 by entering the continuous pores of the sintered compact and being integrated with the sintered compact. The sponge body 3 formed of the PVAt-based porous material may be obtained by, for example, forming an aqueous solution by mixing one or more types of polyvinyl alcohols (raw materials) having an average degree of polymerization of 500 to 3000 and a degree of saponification of 80% or more; adding aldehydes as a cross-linking agent, mineral acids as a catalyst, starch as a pore-forming agent, and the like to the above aqueous solution; injecting the resultant mixture liquid of them into a given mold 11 as illustrated in
The mold 11 includes an outer mold 12, an inner mold 13, a bottom plate 14, and a cap 15. The outer mold 12 and the inner mold 13 are both formed in cylindrical shapes. The inner mold 13 has an outer diameter equal to or slightly smaller than an inner diameter of the outer mold 12, and is inserted into the outer mold 12. The core 2 is inserted into approximately the center of the inner mold 13. The bottom plate 14 closes the lower ends of the outer mold 12 and the inner mold 13 and supports the lower end of the core 2. The cap 15 is fitted to the inner circumferential surface of the upper end of the outer mold 12. The core 2 is positioned by the bottom plate 14 and the cap 15.
A space 16 in an approximately cylindrical shape for forming the sponge body 3 is defined between the inner circumferential surface of the inner mold 13 and the outer circumferential surface of the core 2. In the inner mold 13, multiple through holes 17 for forming the nodules 5 are formed and each through hole 17 communicates with the space 16. The mixture liquid is injected into the space 16 from a casting nozzle 18 inserted between the outer mold 12 and the cap 15 and flows into each through hole 17 from the space 16. At the same time, the air inside the through holes 17 is moved to the space 16 and is discharged into the ambient atmosphere from the upper end of the space 16. In this way, the mixture liquid is certainly filled into the tip ends of the through holes 17.
The sponge body 3 together with the core 2 is taken out of the mold 11 and washed with water. Since the core 2 is formed of the sintered compact having the continuous pores, the mixture liquid injected from the casting nozzle 18 flows through the continuous pores of the core 2 and is filled up to the inner diameter portion of the core 2, and thereby the sponge body 3 is formed to continue from the outer circumferential surface to the inner diameter portion of the core 2.
Since the inner diameter side of the sponge body 3 enters the fine continuous pores of the sintered compact and is integrated with the core 2 while continuing in the densely intricate state as described above, the sponge body 3 can be fixed to the core 2 more strongly than in a case where water passing holes are formed in a core not having continuous pores and a sponge body enters the water passing holes.
The sponge roller 1 can be used suitably for scrub cleaning. The scrub cleaning is processing with the aim of, after chemical mechanical polishing (CMP) of a surface to be cleaned using a slurry abrasive together with a urethane pad or the like, removing particles, mainly the slurry abrasive, from the surface to be cleaned. As the cleaning liquid, pure water, an alkaline solution (for example, ammonia), or an acidic solution (for example, dilute hydrofluoric acid) is used.
In the case where scrub cleaning is performed by using the sponge roller 1 illustrated in
In the case where the core 2 includes non-sponge supporting regions not covered with the sponge body 3 (both end portions in the example in
In the sintered compact, an average pore diameter is preferably 5 μm to 800 μm and a porosity is preferably 30% to 50%. This is because too small an average pore diameter and too low a porosity may result in an increase in the pressure loss during water passing, whereas too large an average pore diameter and too high a porosity may result in a failure to secure a sufficient strength.
The above porosity is a value obtained by measuring a cuboid sintered compact in a dry state, which has been thoroughly dried with a dryer, with a dry automatic densitometer and calculated in accordance with the following formula (1) using the apparent volume and the true volume of the cuboid.
Porosity (%)=(Apparent Volume−True Volume)/Apparent Volume×100 . . . (1)
The above average pore diameter is an average value of the diameters of multiple pores present in the internal structure of the sintered compact. The value of the average pore diameter specified in the present embodiment is a value measured by using a mercury porosimeter.
In order to suppress an increase in pressure loss during water passing for supplying cleaning water (cleaning liquid) from the cleaning device to the inner diameter portion of the core 2, it is preferable that a space (water passing space) continuously extending in the axial direction be secured in the inner diameter portion of the core 2 instead of filling the inner diameter portion of the core 2 with the sponge body 3. For this purpose, in the present embodiment, an excess of the sponge body that enters the inner diameter portion of the core 2 during the production of the sponge body 3 is cut off and removed after the sponge body 3 is produced. Here, in order to prevent an excess of the sponge body from being generated in the inner diameter portion of the core 2, a circular columnar or cylindrical shielding shaft 19 (see
Next, Example of the present invention will be described as compared with Comparative Example.
A mixture liquid was prepared by forming an aqueous solution of polyvinyl alcohol and adding aldehydes as a cross-linking agent, acid as a catalyst, starch as a pore diameter forming material, and the like to the above aqueous solution. The mixture liquid was poured into the mold 11 to which the core 2 was attached as illustrated in
As the core 2, a polypropylene sintered compact (a pore diameter (hole diameter) of 60 μm to 150 μm and a porosity (hole rate) of 30% to 35%) in a cylindrical shape (an outer diameter of 30 mm, an inner diameter of 18 mm, and a length of 300 mm) was used.
As illustrated in
Each of the sponge roller 1 of Example and the sponge roller 21 of Comparative Example was evaluated by supplying water from one end surface of the core 2 or 22 to the inner diameter portion of the core 2 or 22, and observing how the supplied water permeated the sponge body 3 from the inner diameter portion of the core 2 or 22 and flowed out from the outer circumferential surface of the sponge body 3.
To evaluate the water permeability, a tub for receiving water flowing and dropping out from the outer circumferential surface of the sponge body 3 was placed under the sponge body 3. The inside of the tub was partitioned at equal intervals in the longitudinal direction into five areas (areas A to E illustrated in
In the test, the water volume difference was obtained in each of the cases where the volume of water (set water volume) to be supplied to each of the cores 2 and 22 was 250 mL/min, 500 mL/min, 1000 mL/min, 1500 mL/min, and 2000 mL/min, and the water permeability was judged as good (○) when the water volume difference was 50 mL or less, fair (Δ) when the water volume difference was more than 50 mL and not more than 100 mL, and poor (x) when the water volume difference was more than 100 mL.
As shown in
In contrast, in Example, the water volume difference was 50 mL or less with any set water volume, and it was found that variation in the volume of permeation due to a positional difference in the axial direction was small and water flowed out from the outer circumferential surface of the sponge body 3 evenly in the axial direction (longitudinal direction).
In addition, how water flowed out from the outer circumferential surface of the sponge body 3 at an early stage of water passing was observed by supplying a fluorescent liquid (water mixed with a fluorescent substance) and Example and Comparative Example were compared.
In Comparative Example, it is seen that a high volume of water flowed out from around the center portion of the sponge body in the axial direction as shown in
An external force was applied to the sponge body 3, and whether torsion occurred in the sponge body 3 (the sponge body 3 moved relative to the core 2 or 22 in a rotational direction) was checked for Example and Comparative Example.
The sponge roller 1 or 21 (the core 2 or 22) was attached to a scrub cleaning simulator (not illustrated) and rotated at 800 rpm. In order to make it easier to check whether torsion occurred, a substrate (glass plate) 30 was arranged obliquely to the sponge roller 1 or 21 (a distance L1 from the axial center of one end of the core 2 or 22 to the outer circumferential surface of the sponge body 3 was set shorter by 2 mm than a distance L2 from the axial center of the other end of the core 2 or 22 to the outer circumferential surface of the sponge body 3) as illustrated in
In
An external force was applied to the sponge body 3, and whether the sponge body 3 moved relative to the core 2 or 22 in the axial direction was checked for Example and Comparative Example.
As illustrated in
In
From the above results of the tests, it was confirmed that the sponge roller 1 in Example was superior in water permeability and durability to the sponge roller 21 in Comparative Example.
It should be noted that the present invention is not limited to the above embodiment, Example, and a modification thereof merely described as examples, but may be modified in various ways depending on design and the like without departing from the technical idea according to the present invention.
For example, the material for the sponge body 3 is not limited to the PVAt-based porous material, and may be any porous material having continuous pores and having elasticity in a wet state.
The present invention is widely usable as cleaning sponge rollers.
1, 21 cleaning sponge roller
2, 22 core
3 sponge body
4 outer circumferential surface of sponge body
5 nodule of sponge body
| Number | Date | Country | Kind |
|---|---|---|---|
| 2020-134743 | Aug 2020 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2021/029016 | 8/4/2021 | WO |
