JP2020174144A - Substrate cleaning sponge and manufacturing method therefor - Google Patents

Abstract

To provide a substrate cleaning sponge which is enhanced in cleaning characteristic and cleaning efficiency, and a method for manufacturing the same.SOLUTION: A substrate cleaning sponge has, as a whole shape, a stepped cylindrical shape composed of a small diameter portion 20 and a large diameter portion 30 continuous with the small diameter portion 20. An end surface 21 of any one of the small diameter portion 20 and the large diameter portion 30 is set as a cleaning surface 40 which slides while an end surface of the other portion is in contact with a cleaning target, and the substrate cleaning sponge has continuous exposed pores at least on the cleaning surface 40, and is formed of resin sponge having a hydrophilic property. On the cleaning surface 40 is formed a cross-shaped groove including two linear grooves 50 that pass through an outer edge 41 and a center 42 of the cleaning surface 40, are substantially orthogonal to each other at the position of the center 42, have both side walls perpendicular to the cleaning surface 40, and have a predetermined depth.SELECTED DRAWING: Figure 1

Description

The present invention relates to a substrate cleaning sponge used in a process for cleaning an object to be polished, such as a silicon wafer or a glass substrate, which requires a high degree of surface flatness, and a method for manufacturing the same.

In recent years, with the advancement of technology, it has been required to efficiently produce more advanced semiconductors and the like, and a technology for highly flattening the surface of a silicon wafer or the like as a raw material thereof is required.

Chemical mechanical polishing (hereinafter referred to as CMP) is generally used as a method for polishing an object to be polished, such as a silicon wafer or a glass substrate, which requires a high degree of surface flatness. This CMP uses an object to be polished fixed to a rotatable surface plate and a polishing pad provided to be rotatable and movable, and supplies a slurry (polishing liquid) between the object to be polished and the polishing pad. This is a method of polishing by relatively sliding the arm in the front-back and left-right directions while keeping the polishing pad in contact with the surface of the object to be polished, and the operation of rotating the axis and the surface plate. As a result, in addition to the chemical action due to the acidic or alkaline properties of the slurry, the polishing process is performed by utilizing the mechanical action of the abrasive grains contained in the slurry.

Then, when the polishing step by CMP is completed, a cleaning step for cleaning foreign substances such as slurry and polishing debris remaining on the surface of the object to be polished is carried out (hereinafter, the object to be polished is referred to as an object to be polished).

At this time, for example, as described in JP-A-9-134896 (Patent Document 1) or JP-A-10-92780 (Patent Document 2), a rotatable cylindrical sponge is used to be cleaned. The cleaning surface of the sponge is brought into contact with the surface of the sponge, and the cleaning liquid is supplied between the object to be cleaned and the sponge while the object to be cleaned and the sponge are rotated to relatively move the object to be cleaned. A method for removing foreign matter remaining on the surface is generally known.

Specifically, as shown in FIG. 9, this cleaning method uses a substrate cleaning sponge S attached to a holder 3 provided at the tip of the arm 1 via a rotating shaft 2, and a rotatable platen 4 The cleaning liquid R is supplied between the substrate cleaning sponge S and the surface 5 of the object B to be cleaned, and the substrate cleaning sponge S is brought into contact with the surface 5 of the object B to be cleaned. Sponge, polishing debris, etc. remaining on the surface 5 of the object to be cleaned B are removed by relatively sliding the arm 2 in the front-back and left-right directions and the rotation shaft 2 and the platen 4 in the axial rotation. This is a method of washing away foreign substances.

At this time, in order to improve the cleaning characteristics and the cleaning efficiency, it is important that the substrate cleaning sponge itself comes into uniform contact with the object to be cleaned. In addition, it is necessary to uniformly supply new cleaning liquid and efficiently discharge used cleaning liquid.

Therefore, there has been a demand for a substrate cleaning sponge capable of improving cleaning characteristics and cleaning efficiency.

Japanese Unexamined Patent Publication No. 9-134896 Japanese Unexamined Patent Publication No. 10-92780

An object of the present invention is to provide a substrate cleaning sponge having improved cleaning characteristics and cleaning efficiency, and a method for producing the same.

The present invention made to solve the above problems has a stepped columnar shape having a small diameter portion and a large diameter portion continuous with the small diameter portion, and has an end surface of either the small diameter portion or the large diameter portion. Is a substrate cleaning sponge formed of a resin sponge having continuous pores exposed at least on the cleaning surface and having hydrophilicity, which is a cleaning surface that slides while being in contact with the object to be cleaned. A cross groove consisting of two linear grooves that pass through the outer edge and center of the cleaning surface and are substantially orthogonal to each other at the center position, and both side walls are perpendicular to the cleaning surface and have a predetermined depth. Is formed.

When the resin sponge is a polyvinyl alcohol sponge (PVA sponge), the PVA sponge is a resin sponge having a three-dimensional network structure having continuous pores and having hydrophilicity, and is rich in water absorption and water retention and chemical resistance. It can be a substrate cleaning sponge having excellent properties and abrasion resistance.

Further, it is desirable that the resin sponge has an average pore diameter of 80 μm to 180 μm.

Further, the method for producing a substrate cleaning sponge is characterized by having the following steps.
1. 1. A small diameter portion and a large diameter portion are formed by cutting the outer periphery of the block body of the resin sponge swollen with water or the cleaning liquid to be used.
2. A cleaning surface is formed by cutting the end surface of either the small diameter portion or the large diameter portion to form a cross groove.

According to the substrate cleaning sponge of the present invention, since the whole is composed of a single resin continuous pore body, the entire cleaning surface can be uniformly brought into contact with the surface to be cleaned by absorbing a certain pressure by the pores. Not only is it excellent in that it can be made and that foreign matter can be efficiently collected by the pores exposed on the cleaning surface, but also a conventional groove is formed by forming a cross groove whose edge is perpendicular to the cleaning surface. Compared to a substrate cleaning sponge that does not have a right angle and a substrate cleaning sponge that has grooves other than right angles, it not only improves cleaning characteristics and cleaning efficiency at each stage, but also facilitates processing and has manufacturing advantages. Is.

(A) perspective view, (b) plan view, and (c) AA line sectional view showing a preferred embodiment of the present invention. FIG. 1 (c) is a further enlarged view. The explanatory view which shows the manufacturing process of the substrate cleaning sponge shown in FIG. (A) perspective view, (b) plan view, and (c) AA line sectional view showing different embodiments of the present invention. An enlarged cross-sectional view of a main part showing a usage state in the embodiment shown in FIG. A perspective showing a substrate cleaning sponge (invention of the present application) shown in FIG. 1, a substrate cleaning sponge having no grooves (Comparative Example 1), and a substrate cleaning sponge having grooves formed in a grid pattern (Comparative Example 2). List of figures and plan views. A table showing the number of residual particles before and after cleaning when the substrate cleaning sponge shown in FIG. 1 and the substrate cleaning sponges of Comparative Examples 1 and 2 are used in the cleaning step. It is sectional drawing which shows a different comparative example, (a) is a substrate cleaning sponge whose groove is an obtuse angle with respect to a cleaning surface, (b) is a substrate cleaning sponge whose groove is an acute angle with respect to a cleaning surface. The figure which shows the conventional cleaning apparatus.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a diagram showing a substrate cleaning sponge 10A of the present invention. As shown in this figure, the substrate cleaning sponge 10A is a stepped cylinder composed of a small diameter portion 20 and a large diameter portion 30 continuous with the small diameter portion 20. It is a shape.

The end surface 21 of the small diameter portion 20 is provided with a cleaning surface 40 that slides on the object to be cleaned B, and the cleaning surface 40 is a linear shape that passes through the outer edge 41 and the center 42 and is substantially orthogonal to each other at the position of the center 42. A cross groove is formed by the two grooves 50 and 50.

The groove 50 is formed by cutting a predetermined depth from the cleaning surface 40, and the side walls 51 and 51 of the groove 50 are perpendicular to the cleaning surface 40.

The depth H1 of the groove 50 is preferably about half of the height H2 of the small diameter portion 20, but is not particularly limited to this, and can be arbitrarily set with the height H2 of the small diameter portion 20 as the upper limit ( See FIG. 2).

The width W1 of the groove 50 is preferably in the range of 10% to 20% with respect to the width W2 of the small diameter portion 20 (see FIG. 2).

The substrate cleaning sponge 10A is entirely formed of a resin sponge having continuous pores exposed on the cleaning surface 40, and a polyvinyl alcohol sponge (hereinafter referred to as PVA sponge) is used as the resin sponge in the present embodiment. ing.

PVA sponge is a resin sponge having a three-dimensional network structure with continuous pores and having hydrophilicity. It is rich in water absorption and water retention, and has excellent chemical resistance and abrasion resistance, so it is used as a sponge for cleaning substrates. Although it is a very suitable material, for example, a polyvinyl-based resin continuous pore body other than the PVA sponge or other resin sponge may be used.

As the PVA sponge, for example, Belle Eater D (D) or Belle Eater Y (D) manufactured by Aion Co., Ltd. can be used, and the basic physical properties thereof are as shown in Table 1 below.

The process for manufacturing the substrate cleaning sponge 10A is as follows.

First, the resin sponge is molded into a long columnar shape and then sliced to a predetermined width to form the block body 11 (see FIG. 3A).

Next, the small diameter portion 20A and the large diameter portion 30A are formed by cutting the outer periphery of the block body 11 (see FIG. 3B).

Then, the cleaning surface 40 is formed by cutting the end surface 21 of the small diameter portion 20A to form the cross groove (see FIG. 3C).

The above step is particularly desirable because it is possible to mold the resin sponge according to the dimensions when it is actually used in the cleaning step by processing it in a wet state in which a liquid is impregnated. As the liquid to be impregnated, water or the cleaning liquid to be used can be used.

In this way, by cutting the entire surface of the long columnar resin sponge to form the substrate cleaning sponge 10A, the texture of the mold surface is transferred and open cells are buried when the long columnar resin sponge is molded. Therefore, it is possible to easily expose the continuous pores to the surface.

FIG. 4 is a diagram showing a substrate cleaning sponge 10B according to a different embodiment of the present invention. Similar to the substrate cleaning sponge 10A shown in FIG. 1, the substrate cleaning sponge 10B has a small diameter portion 20 and a small diameter portion 20. It is a stepped columnar shape composed of continuous large-diameter portions 30.

The substrate cleaning sponge 10B is different from the substrate cleaning sponge 10A shown in FIG. 1 in that the end surface 31 of the large-diameter portion 30 is provided with a cleaning surface 40 that slides on the object to be cleaned B. Is a cross formed by two linear grooves 50, 50 that pass through the outer edge 41 and the center 42 and are substantially orthogonal to each other at the center position, and the side walls 51, 51 are perpendicular to the cleaning surface 40. A groove is formed.

The substrate cleaning sponge 10A shown in FIG. 1 and the substrate cleaning sponge 10B shown in FIG. 4 are used properly according to the shape suitable for the device to be mounted, and their functions are almost the same. In this specification, the substrate cleaning sponge 10A shown in FIG. 1 will be described.

FIG. 5 is an enlarged cross-sectional view of a main part showing a usage state in which the substrate cleaning sponge 10A shown in FIG. 1 is used as the substrate cleaning sponge in the conventional cleaning apparatus shown in FIG. 7, and is the same as FIG. The same reference numerals are given to the parts of the configuration.

As shown in FIG. 5B, the supplied cleaning liquid R is guided inside the groove 50 of the rotating and moving substrate cleaning sponge 10A, and after cleaning the surface 5 of the object to be cleaned B, the object to be cleaned B The substrate cleaning sponge 10A has a groove 50 formed at a right angle to the cleaning surface 40, so that the edge portion 52 can guide the cleaning liquid R, foreign matter, etc. like a scraper. Since it is a linear groove, it can be easily machined with a cutting tool.

FIG. 6 shows a substrate cleaning sponge 10A (invention of the present application), a substrate cleaning sponge 10C having no grooves formed on the cleaning surface (Comparative Example 1), and a substrate cleaning sponge 10D having grooves formed in a grid pattern on the cleaning surface (comparison). It is a table which shows Example 2).

FIG. 7 shows before and after cleaning of a silicon wafer using a substrate cleaning sponge 10A (invention of the present application), a substrate cleaning sponge 10C (Comparative Example 1), and a substrate cleaning sponge 10D (Comparative Example 2). It is a table which shows the number of residual particles and the removal rate after cleaning. The item name "0.1up" is a column indicating the number of particles of 0.1 micron or more, and "0.15up" is a column indicating the number of particles of 0.15 micron or more.

As shown in FIG. 7, the substrate cleaning sponge 10C of Comparative Example 1 which does not form a groove has been generally used in the past, but its cleaning performance is not sufficient, and the particle removal rate of 0.15 micron or more. Is about 77% (first time) and about 80% (second time), and about 20% of the particles of 0.15 micron or more remain.

Furthermore, since the particle removal rate of 0.1 micron or more is about 45% (first time) and about 52% (second time), almost half of the particles of 0.1 micron or more remain. ..

On the other hand, the substrate cleaning sponge 10A of the present invention has a particle removal rate of 0.15 micron or more of 99.64% (first time) and 99.21% (second time), which far surpasses Comparative Example 1. Demonstrate cleaning performance. Furthermore, it has been shown that the particle removal rate of 0.1 micron or more is 98% or more, and it is clear that the cleaning performance is very effective even for extremely fine foreign substances.

Comparative Example 2 in which the grid-like grooves are formed exhibits better cleaning performance than Comparative Example 1, but the particle removal rate of 0.1 micron or more is 98% or more in the present invention. Since Comparative Example 2 is about 85%, there is a large difference, and it cannot be said that the cleaning performance is sufficient. It is presumed that the reason for this is that the number of grooves is too large, the flow of the cleaning liquid flowing between the inside and the outside of the base cleaning sponge is disturbed, and the cleaning liquid after use is not discharged well.

FIG. 8 is a cross-sectional view showing a different comparative example, and when the groove 50E is formed at an obtuse angle with respect to the cleaning surface 40 as in the substrate cleaning sponge 10E shown in FIG. 8A, the substrate shown in FIG. 1 Compared with the cleaning sponge 10A, the edge portion acts like a scraper less, and the volume of the groove 50E is reduced, so that the amount of the cleaning liquid R that can be retained is reduced. Further, when the groove 50F is formed at a sharp angle with respect to the cleaning surface 40 as in the substrate cleaning sponge 10F shown in FIG. 8B, the edge effect is higher than that of the substrate cleaning sponge 10A shown in FIG. Although the number increases, the cleaning liquid R flows toward the back of the groove 10F, so that the cleaning liquid R is not updated smoothly, and the groove shape is further formed, which makes processing difficult.

As described above, according to the substrate cleaning sponge of the present invention, the PVA sponge constituting the substrate cleaning sponge is a resin continuous pore body having a three-dimensional network structure having continuous pores, and is formed by cutting the whole. As a result, not only is it possible to absorb a certain amount of pressure through the pores and bring the entire cleaning surface into uniform contact with the surface to be cleaned, but also to retain and renew the cleaning liquid and foreign matter in the continuous pores exposed on the cleaning surface. Therefore, more efficient cleaning can be performed.

1 arm, 2 rotating shaft, 3 holder, 4 surface plate, 5 surface, 10A, 10B, 10C, 10D Substrate cleaning sponge, 11 block body, 20 small diameter part, 21 end face, 30 large diameter part, 31 end face, 40 cleaning Surface, 41 outer edge, 42 center, 50, 50C, 50D groove, 51 side wall, 52 edge part, B object to be cleaned, S sponge for cleaning substrate, R cleaning liquid, H1 groove depth, H2 small diameter part height, W1 Groove width, W2 small diameter part width

Claims (4)

Cleaning that has a stepped columnar shape as a whole consisting of a small diameter portion and a large diameter portion continuous with the small diameter portion, and slides while the end surface of either the small diameter portion or the large diameter portion is in contact with the object to be cleaned. A substrate cleaning sponge formed of a resin sponge having continuous pores exposed at least on the cleaning surface and having hydrophilicity.
From two grooves that pass through the outer edge and center of the cleaning surface and are substantially orthogonal to each other at the center position, and both side walls are at right angles to the cleaning surface and have a predetermined depth. A sponge for cleaning a substrate, characterized in that a cross groove is formed. The substrate cleaning sponge according to claim 1, wherein the resin sponge is a polyvinyl alcohol sponge (PVA sponge). The substrate cleaning sponge according to claim 1 or 2, wherein the resin sponge has an average pore diameter of 80 μm to 180 μm. The method for producing a substrate cleaning sponge according to any one of claims 1, 2 or 3, wherein the method for producing a substrate cleaning sponge includes the following steps.
1. 1. A small diameter portion and a large diameter portion are formed by cutting the outer periphery of the block body of the resin sponge swollen with water or the cleaning liquid to be used.
2. A cleaning surface is formed by cutting the end surface of either the small diameter portion or the large diameter portion to form a cross groove.

Images