WO2024106537A1 - Water-repellent film, water-repellent electrostatic attraction sheet, electrostatic attraction support member, and method for manufacturing water-repellent electrostatic attraction sheet - Google Patents

Abstract

A water-repellent film (11, 21) can be statically charged and is for use in electrostatic attraction, and has an angle of contact of 100° or more with respect to water, a relative permittivity of 2.0 or more, and a thickness of 50-2000 nm. A water-repellent electrostatic attraction sheet (10, 30) has the water-repellent film (11, 21), and a first resin sheet (12) that supports the same.

Description

Water-repellent film, water-repellent electrostatic adhesion sheet, electrostatic adhesion support member, and method for manufacturing water-repellent electrostatic adhesion sheet

The present invention relates to a water-repellent film, a water-repellent electrostatic adhesion sheet using the same, an electrostatic adhesion support member, and a method for producing a water-repellent electrostatic adhesion sheet.
This application claims priority based on Japanese Patent Application No. 2022-184874 filed in Japan on November 18, 2022, and Japanese Patent Application No. 2023-090285 filed in Japan on May 31, 2023, the contents of which are incorporated herein by reference.

For example, electrostatic adsorption devices are widely used as a method for fixing wafers and the like onto the stage of a processing device. For example, Patent Document 1 discloses a reinforcing device for adsorbing and reinforcing a thin plate-shaped reinforcement object by electrostatic adsorption, the reinforcing device comprising a reinforcing material main body having an electrostatic holding part with an electrode part embedded therein, a first connection terminal capable of grounding the reinforcement object, and a second connection terminal capable of conducting the electrode part to ground or to a high voltage.

For example, Patent Document 2 discloses an electrostatic chuck that includes a water-repellent material that contains an electrode, and a potential difference applying means that applies a potential difference between the electrode and a semiconductor wafer placed on the water-repellent material. With such an electrostatic chuck, it is said that the electrostatic chuck to which the semiconductor wafer is electrostatically attracted can be carried without a continuous power supply.

Patent No. 5112808 Japanese Patent Application Laid-Open No. 9-36212

However, the electrostatic reinforcing device disclosed in Patent Document 1 is designed to be incorporated into semiconductor manufacturing equipment, and so there is a problem in that it is difficult to process the object to be attracted with a liquid, such as water, while it is still electrostatically attracted.

In addition, the electrostatic chuck disclosed in Patent Document 2 has an electrode on which the semiconductor wafer is placed covered with a water-repellent material. However, when the semiconductor wafer is immersed in liquid together with the electrostatic chuck, liquid may seep in between the electrostatic chuck and the semiconductor wafer, causing the electrostatic adhesion to be released. Therefore, there is a need for more reliable water repellency.

The present invention has been made in consideration of the above-mentioned circumstances, and aims to provide a chargeable water-repellent film for use in electrostatic adsorption, which enables an object to be held without the electrostatic adsorption being released even in liquid.
Another object of the present invention is to provide a water-repellent electrostatic attraction sheet that uses such a water-repellent film and is disposed between an electrostatic chuck and an object to be attracted, enabling the electrostatic attraction state to be maintained even in liquid.
Furthermore, an object of the present invention is to provide an electrostatic adsorption support member that uses such a water-repellent film to enable an object to be adsorbed to be moved while being electrostatically adsorbed, and that can maintain the electrostatic adsorption state even in liquid.

In order to solve the above problems, the water-repellent film of aspect 1 of the present invention is a chargeable water-repellent film used for electrostatic adsorption, characterized in that the water-repellent film has a contact angle with water of 100° or more, a relative dielectric constant of 2.0 or more, and a thickness of 50 nm or more and 2000 nm or less.
The contact angle of the water repellent film to water is not limited, but may be 100° or more and 120° or less. The relative dielectric constant of the water repellent film is not limited, but may be 2.0 or more and 15.0 or less. The thickness of the water repellent film is not limited, but may be 75 to 1500 nm. In addition, the contact angle to hexadecane (oil repellency) is not limited, but may be 40° or more and 80° or less.

　上記式（１）及び上記式（２）中、ｐ、ｑ及びｒは、それぞれ同一又は互いに異なる１～６の整数であって、直鎖状又は分岐状であってもよい。また上記式（１）及び上記式（２）中、Ｘは、炭素数２～１０の炭化水素基であって、エーテル結合、ＣＯ－ＮＨ結合、Ｏ－ＣＯ－ＮＨ結合及びスルホンアミド結合から選択される１種以上の結合を含んでいてもよい。更に上記式（１）及び上記式（２）中、Ｙはシランの加水分解体又はシリカゾルの主成分である。
　前記金属酸化物粒子（Ｂ）の平均粒子径は、限定はされないが、１５ｎｍ以上２００ｎｍ以下であってもよい。前記フッ素系官能基成分（Ａ）は、限定はされないが、前記撥水性膜の全体を１００質量％とした時に０．６質量％以上２０質量％以下の割合で含まれていてもよい。前記金属酸化物粒子（Ｂ）は、限定はされないが、前記撥水性膜の全体を１００質量％とした時に１５質量％以上７５質量％以下の割合で含まれていてもよい。 Aspect 2 of the present invention is characterized in that, in the water-repellent film of Aspect 1, the water-repellent film comprises metal oxide particles (B) having an average particle size of 10 nm or more and 210 nm or less and bonded to a fluorine-based functional group component (A) containing a perfluoroether structure represented by the following general formula (1) or formula (2), and silica sol (C), wherein the fluorine-based functional group component (A) is contained in an amount of 0.5 mass% or more and 25 mass% or less when the entire water-repellent film is taken as 100 mass%, and the metal oxide particles (B) are contained in an amount of 10 mass% or more and 80 mass% or less when the entire water-repellent film is taken as 100 mass%.

In the above formulas (1) and (2), p, q, and r are each the same or different integers of 1 to 6, and may be linear or branched. In addition, in the above formulas (1) and (2), X is a hydrocarbon group having 2 to 10 carbon atoms, and may contain one or more bonds selected from an ether bond, a CO-NH bond, an O-CO-NH bond, and a sulfonamide bond. Furthermore, in the above formulas (1) and (2), Y is a silane hydrolyzate or a main component of a silica sol.
The average particle size of the metal oxide particles (B) is not limited, but may be 15 nm or more and 200 nm or less. The fluorine-based functional group component (A) may be contained in a proportion of 0.6 mass % or more and 20 mass % or less when the entire water-repellent film is taken as 100 mass %. The metal oxide particles (B) are not limited, but may be contained in a proportion of 15 mass % or more and 75 mass % or less when the entire water-repellent film is taken as 100 mass %.

Aspect 3 of the present invention is characterized in that in the water-repellent film of aspect 1 or aspect 2, the metal oxide particles (B) are one or more oxide particles selected from the group consisting of Si, Al, Mg, Ca, Ti, Zn, Zr, and Ba.

The water-repellent electrostatic adsorption sheet of aspect 4 of the present invention is a water-repellent electrostatic adsorption sheet disposed between the electrostatic chuck of an electrostatic adsorption device and a substrate that is an object to be adsorbed, and is characterized by having the water-repellent film described in aspect 1 or 2 and a first resin sheet that supports the water-repellent film.

Aspect 5 of the present invention is characterized in that in the water-repellent electrostatically adhesive sheet of aspect 4, the first resin sheet contains a polyimide resin.

The water-repellent electrostatic adsorption sheet of aspect 6 of the present invention is a water-repellent electrostatic adsorption sheet disposed between the electrostatic chuck of an electrostatic adsorption device and a substrate that is an object to be adsorbed, and is characterized by having the water-repellent film described in aspect 1 or 2, and a metal oxide layer that supports the water-repellent film and has a thickness of 1 nm or more and 50 nm or less.

Aspect 7 of the present invention is characterized in that in the water-repellent electrostatic adsorption sheet of aspect 6, the metal oxide layer is made of one or more metal oxides selected from the group consisting of Si, Al, Mg, Ca, Ti, Zn, Zr, Sr, Hf, and Ba.

The electrostatic adhesion support member of aspect 8 of the present invention is an electrostatic adhesion support member that is detachably attached to an electrostatic adhesion device, and is characterized by having a dielectric plate, an electrode film formed on one side of the dielectric plate, a second resin sheet disposed on one side of the electrode film, and the water-repellent film described in aspect 1 or 2 disposed on top of one side of the second resin sheet.

Aspect 9 of the present invention is characterized in that in the water-repellent electrostatically adhesive sheet described in aspect 8, the second resin sheet contains a polyimide resin.

Aspect 10 of the present invention is characterized in that in the water-repellent electrostatic adsorption sheet according to aspect 8 or 9, a metal oxide layer having a thickness of 1 nm or more and 50 nm or less that supports the water-repellent film is disposed between the second resin sheet and the water-repellent film.

The method for producing a water-repellent electrostatic adhesion sheet according to aspect 11 of the present invention is the method for producing a water-repellent electrostatic adhesion sheet according to aspect 4 or 5, and is characterized by including the steps of mixing a dispersion of the metal oxide particles to which the fluorine-based functional group component (A) is bonded with a silica sol liquid to prepare a liquid composition for forming a water-repellent film, and forming a diluted liquid of the liquid composition for forming a water-repellent film on a first resin sheet by spin coating.

The method for producing a water-repellent electrostatic adhesion sheet according to aspect 12 of the present invention is the method for producing a water-repellent electrostatic adhesion sheet according to aspect 6 or 7, and is characterized by including the steps of forming the metal oxide layer on a first resin sheet, mixing a dispersion of the metal oxide particles to which the fluorine-based functional group component (A) is bonded with a silica sol liquid to prepare a liquid composition for forming a water-repellent film, and forming a diluted liquid of the liquid composition for forming a water-repellent film on the metal oxide layer by spin coating.

The present invention makes it possible to provide a chargeable water-repellent film for use in electrostatic adhesion, which enables an object to be held without being released from electrostatic adhesion even in liquid. In addition, by using such a water-repellent film, it is possible to provide a water-repellent electrostatic adhesion sheet that is disposed between the electrostatic chuck and the object to be attracted, and enables the electrostatic adhesion state to be maintained even in liquid. Furthermore, by using such a water-repellent film, it is possible to provide an electrostatic adhesion support member that enables the object to be moved while being electrostatically attracted, and enables the electrostatic adhesion state to be maintained even in liquid.

1 is a schematic cross-sectional view showing a water-repellent electrostatic adsorption sheet having a water-repellent film according to a first embodiment of the present invention. 1 is a schematic cross-sectional view showing an electrostatic adsorption support member having a water-repellent film according to a first embodiment of the present invention. FIG. 1 is a flowchart illustrating a step-by-step method for manufacturing a water-repellent electrostatic adhesive sheet according to a first embodiment of the present invention. 13 is a photograph showing a verification example (water immersion test). 13 is a photograph showing the results of a verification example (water immersion test). FIG. 5 is a schematic cross-sectional view showing a water-repellent electrostatic adsorption sheet having a water-repellent film according to a second embodiment of the present invention. FIG. 11 is a schematic cross-sectional view showing an electrostatic adsorption support member having a water-repellent film according to a second embodiment of the present invention.

Below, a water-repellent film, a water-repellent electrostatic adhesion sheet, an electrostatic adhesion support member, and a method for manufacturing a water-repellent electrostatic adhesion sheet according to one embodiment of the present invention will be described with reference to the drawings. Note that each embodiment shown below is specifically described to provide a better understanding of the gist of the invention, and does not limit the present invention unless otherwise specified. Furthermore, the drawings used in the following description may show key parts enlarged for the sake of convenience in order to make the features of the present invention easier to understand, and the dimensional ratios of each component may not necessarily be the same as in reality.

[Water-repellent film, water-repellent electrostatic adsorption sheet: First embodiment]
FIG. 1 is a schematic cross-sectional view showing a water-repellent electrostatic adhesion sheet having a water-repellent film according to a first embodiment of the present invention.
The water-repellent electrostatic adsorption sheet 10 of the first embodiment is a member that is arranged, for example, between the electrostatic adsorption stage 2 of the electrostatic adsorption device 1 and a wafer 3, which is an example of an object to be adsorbed, and adsorbs the wafer 3 to the electrostatic adsorption stage 2 by electrostatic adsorption having water-repellent properties.

The electrostatic attraction device 1 may be either a monopolar or bipolar type. When the electrostatic attraction device 1 is a monopolar type, a voltage is applied between the electrostatic attraction stage 2 and the wafer (object to be attracted) 3, one side is positively charged and the other side is negatively charged, and the wafer 3 is electrostatically attracted to the electrostatic attraction stage 2 with a water-repellent film 11, which will be described in detail later, sandwiched therebetween.

When the electrostatic attraction device 1 is a bipolar type, one part of the electrostatic attraction stage 2 is charged positively and the other part is charged negatively, while the opposing wafer 3 is charged in the opposite direction, so that the wafer 3 is electrostatically attracted to the electrostatic attraction stage 2 with the water-repellent film 11 sandwiched between them.

The electrostatic adsorption stage 2 of the electrostatic adsorption device 1 may, for example, be configured so that an electrode is formed inside and that it is covered with a dielectric material.

The water-repellent electrostatic adsorption sheet 10 of this embodiment has a water-repellent film 11 of one embodiment of the present invention and a resin sheet (first resin sheet) 12 that supports the water-repellent film 11 .
The water-repellent film 11 is an organic material film having a contact angle with respect to water of 100° or more, a relative dielectric constant of 2.0 or more, and a thickness of 50 nm to 2000 nm. The water-repellent film 11 is positively or negatively charged by, for example, being placed on an electrostatic attraction stage 2 to which a voltage is applied, and electrostatically attracts the wafer (object to be attracted) 3. At this time, water repellency and oil repellency are exerted between the wafer 3 and the electrostatic attraction stage 2, preventing the electrostatic attraction from being released due to the intrusion of water or oil.

If the contact angle of the water-repellent film 11 with respect to water is less than 100°, for example, when electrostatic adsorption is performed in an environment where moisture is present, there is a concern that water may penetrate between the wafer 3 and the electrostatic adsorption stage 2, causing the electrostatic adsorption to be released.

In addition, if the relative dielectric constant of the water-repellent film 11 is less than 2.0, there is a concern that the surface will not be charged, resulting in a low electrostatic adsorption force.

Furthermore, if the thickness of the water-repellent film 11 is less than 50 nm, durability will be low, and there is a concern that repeated electrostatic adsorption may cause the film to peel off from the resin sheet 12 or cause partial damage. On the other hand, if the thickness exceeds 2000 nm, the gap between the electrostatic adsorption stage 2 and the wafer 3 may become too wide, causing a concern that the electrostatic adsorption force may decrease.

The resin sheet (first resin sheet) 12 constituting the water-repellent electrostatic adsorption sheet 10 is not particularly limited as long as it is a sheet of a general resin material. In this embodiment, a polyimide resin sheet is used as the resin sheet 12. The thickness of the resin sheet 12 made of polyimide resin may be, for example, in the range of 1 μm or more and 500 μm or less.

The water-repellent film 11 of this embodiment is composed of a water-repellent fluorine-based composition that includes metal oxide particles (B) having an average particle size of 10 nm to 210 nm and bonded to a fluorine-based functional group component (A) containing a perfluoroether structure represented by the above-mentioned general formula (1) or formula (2), and silica sol (C), in which the fluorine-based functional group component (A) is contained in a proportion of 0.5 mass% to 25 mass% when the entire water-repellent film 11 is taken as 100 mass%, and the metal oxide particles (B) are contained in a proportion of 10 mass% to 80 mass% when the entire water-repellent film 11 is taken as 100 mass%.

If the content of the fluorine-based functional group component (A) in the water-repellent film 11 is less than 0.5% by mass, the water-repellent effect is poor and the water-repellent performance is insufficient. In other words, when water reaches the gap between the electrostatic adsorption stage 2 and the wafer 3, the water is not repelled and tends to penetrate between the electrostatic adsorption stage 2 and the wafer 3. Furthermore, if the content of the fluorine-based functional group component (A) exceeds 25% by mass, there is a concern that the adhesion between the water-repellent film 11 and the resin sheet 12 that supports it may decrease. The content of the fluorine-based functional group component (A) in the water-repellent film 11 is preferably 0.5% by mass or more and 25% by mass or less.

The metal oxide particles (B) contained in the water-repellent film 11 may be one or more oxide particles selected from the group consisting of Si, Al, _Mg , Ca, Ti, Zn, Zr, and Ba. For example, spherical oxide particles of _SiO2 , _Al2O3 , CaO, etc. may be used.

The average particle size of the metal oxide particles (B) contained in the water-repellent film 11 is in the range of 10 nm to 210 nm, preferably 15 nm to 200 nm. If the average particle size is less than 10 nm, the metal oxide particles are more likely to aggregate, making it difficult for the metal oxide particles (B) to disperse in the medium when the water-repellent film 11 is formed. If the average particle size exceeds 210 nm, the metal oxide particles (B) are more likely to fall off from the water-repellent film 11.

If the content of metal oxide particles (B) in the water-repellent film 11 is less than 10% by mass, the water-repellent performance of the water-repellent film 11 will decrease. If the content exceeds 80% by mass, the content of silica sol (C) will become relatively low, and there is a concern that the adhesion of the water-repellent film 11 to the resin sheet 12 will decrease.

With the water-repellent electrostatic attraction sheet 10 having the water-repellent film 11 configured as described above, for example, if the water-repellent electrostatic attraction sheet 10 of this embodiment is placed between the electrostatic attraction stage 2 of the electrostatic attraction device 1 and a wafer 3, which is an example of an object to be attracted, the excellent water repellency of the water-repellent film 11 that constitutes the water-repellent electrostatic attraction sheet 10 repels water that penetrates between the electrostatic attraction stage 2 and the wafer 3.

As a result, for example, even if the wafer 3 is electrostatically attracted to the electrostatic attraction stage 2 and then processed using a liquid containing water, water will not enter between the electrostatic attraction stage 2 and the wafer 3, causing the electrostatic attraction to be released. Therefore, by simply placing the water-repellent electrostatic attraction sheet 10 of this embodiment between the electrostatic attraction stage of the electrostatic attraction device and the object to be attracted, it becomes possible to process the object to be attracted using a liquid containing water while maintaining the electrostatic attraction of the object to be attracted.

In addition, the water-repellent electrostatically adsorbent sheet 10 of this embodiment is also oil-repellent, so it is possible to process the object using a liquid containing oils and fats, such as lubricating oil, while still maintaining the electrostatic adsorption of the object.

It is also preferable to perform plasma treatment on the water-repellent film 11 in order to improve the resistance of the water-repellent electrostatic adsorption sheet 10 described above to repeated wiping stress. For example, this can be done by using a plasma treatment device to apply radicals that have been converted into plasma under atmospheric pressure or reduced pressure to the surface of the water-repellent film 11. This modifies the surface of the water-repellent film 11, improving its resistance to repeated wiping stress. For example, even if dirt is repeatedly wiped off the water-repellent electrostatic adsorption sheet 10 after use with a cleaning sheet or the like, the water-repellent film 11 can be prevented from peeling off.

[Water-repellent electrostatic adhesion sheet: second embodiment]
Next, a water-repellent electrostatically adhesive sheet according to a second embodiment of the present invention will be described. Note that the same components as those in the first embodiment are given the same reference numbers, and duplicated descriptions will be omitted.
FIG. 6 is a schematic cross-sectional view showing a water-repellent electrostatically adhesive sheet according to the second embodiment.
The water-repellent electrostatic adsorption sheet 30 of this embodiment has the water-repellent film 11 of one embodiment of the present invention and a metal oxide layer 32 supporting the water-repellent film 11. The metal oxide layer 32 may be disposed on the resin sheet (first resin sheet) 12.

The metal oxide layer 32 is formed to a thickness in the range of 1 nm or more and 50 nm or less. If the thickness of the metal oxide layer 32 is less than 1 nm, there is a concern that it will not contribute to improving the strength of the water-repellent film 11. In addition, if the thickness of the metal oxide layer 32 exceeds 50 nm, there is a concern that it will take a long time to form the film, resulting in high manufacturing costs.

The metal oxide layer 32 is preferably made of one or more metal oxides selected from the group consisting of Si, Al, Mg, Ca, Ti, Zn, Zr, Sr, Hf, and Ba. In this embodiment, a quartz film (SiO ₂ ) is used as the metal oxide layer 32.

In the water-repellent electrostatic adsorption sheet 30 of the second embodiment, a resin sheet 12 with a metal oxide layer 32 is used as a support for the water-repellent film 11, thereby increasing the strength of the water-repellent film 11, for example, its resistance to rubbing stress, and realizing a water-repellent electrostatic adsorption sheet 30 that is resistant to repeated wiping stress.

[Electrostatic Adsorption Support Member: First Embodiment]
FIG. 2 is a schematic cross-sectional view showing an electrostatic adsorption support member of a first embodiment having a water-repellent film according to an embodiment of the present invention.
The electrostatic adsorption support member 20 is, for example, a detachable part of the electrostatic adsorption stage 6 that constitutes the electrostatic adsorption device 5, and is detachably arranged on the stage main body 7 that includes a power supply device, and a wafer 3, an example of an object to be adsorbed, is placed on the upper surface and electrostatically adsorbed.

The electrostatic adsorption support member 20 of this embodiment has a dielectric plate 22, an electrode film 23 formed on one side of the dielectric plate 22, a resin sheet (second resin sheet) 24 arranged on one side of the electrode film 23, and a water-repellent film 21 arranged on one side of the second resin sheet 24.

The dielectric plate 22 may be made of a dielectric material such as an alumina plate or a resin plate. The electrode film 23 is electrically and detachably connected to the power supply device of the stage body 7, and the surface of the water-repellent film 21 is positively or negatively charged by application of a voltage. The power supply device of the stage body 7 also charges the wafer (object to be attracted) 3 with an opposite charge to that of the surface of the water-repellent film 21. With this configuration, the wafer (object to be attracted) 3 is electrostatically attracted to the electrostatic attraction support member 20.

The resin sheet (second resin sheet) 24 that supports the water-repellent film 21 is not particularly limited as long as it is a sheet of a general resin material. In this embodiment, a sheet of polyimide resin is used as the resin sheet 24.

The water-repellent film 21 of this embodiment is an organic material film with a contact angle with water of 100° or more, a relative dielectric constant of 2.0 or more, and a thickness of 50 nm or more and 2000 nm or less, similar to the water-repellent film constituting the water-repellent electrostatic adsorption sheet of the first embodiment. The water-repellent film 21 is positively or negatively charged by the electrode film 23, thereby electrostatically adsorbing the wafer (object to be adsorbed) 3. At this time, the water-repellent film 21 exerts water-repellency and oil-repellency between the wafer 3 and the electrostatic adsorption support member 20, preventing the electrostatic adsorption from being released due to the intrusion of water or oil.

The water-repellent film 21 of this embodiment, like the water-repellent film constituting the water-repellent electrostatic adsorption sheet of the first embodiment, may be composed of a water-repellent fluorine-based composition that contains metal oxide particles (B) with an average particle size of 10 nm to 210 nm and bound to a fluorine-based functional group component (A) containing a perfluoroether structure represented by the above-mentioned general formula (1) or formula (2) and silica sol (C), in which the fluorine-based functional group component (A) is contained in a proportion of 0.5 mass% to 25 mass% when the entire water-repellent film 21 is taken as 100 mass%, and the metal oxide particles (B) are contained in a proportion of 10 mass% to 80 mass% when the entire water-repellent film 21 is taken as 100 mass%.

According to the electrostatic adhesion support member 20 having the water-repellent film 21 configured as described above, for example, the water-repellent film 21 is disposed between the dielectric plate 22 of the electrostatic adhesion support member 20 and the wafer 3, which is an example of an object to be adhered, and the excellent water repellency of the water-repellent film 21 repels water that penetrates between the electrostatic adhesion support member 20 and the wafer 3.

As a result, even if the wafer 3 is electrostatically adsorbed to the electrostatic adsorption support member 20 and then processed using a liquid containing water, water will not enter between the electrostatic adsorption support member 20 and the wafer 3, causing the electrostatic adsorption to be released. Therefore, while the wafer 3 is electrostatically adsorbed to the electrostatic adsorption support member 20 of this embodiment, it is possible to immerse the wafer 3 in, for example, a water tank and perform processing such as water washing.

In addition, since the electrostatic adsorption support member 20 of this embodiment is detachable from the stage body 7 constituting the electrostatic adsorption device 5, the electrostatic adsorption support member 20 that electrostatically adsorbs the wafer 3 can be separated from the electrostatic adsorption device 5 and carried around, and can be installed in another processing device or the like for processing.

In addition, since the water-repellent film 21 of the electrostatic adsorption support member 20 of this embodiment is also oil-repellent, it is possible to process the object to be adsorbed using a liquid containing oils and fats such as lubricating oil while maintaining the electrostatic adsorption of the object to be adsorbed.

[Electrostatic Adsorption Support Member: Second Embodiment]
Next, an electrostatic adsorption supporting member according to a second embodiment of the present invention will be described. Note that the same components as those in the first embodiment are given the same reference numerals, and duplicated descriptions will be omitted.
FIG. 7 is a schematic cross-sectional view showing an electrostatic adsorption support member of a second embodiment having a water-repellent film according to an embodiment of the present invention.

The electrostatic adhesion support member 40 has a dielectric plate 22, an electrode film 23 formed on one side of the dielectric plate 22, a resin sheet (second resin sheet) 24 arranged on one side of the electrode film 23, a metal oxide layer 32 arranged on one side of the second resin sheet 24, and a water-repellent film 21 arranged on one side of the metal oxide layer 32. That is, the electrostatic adhesion support member 40 of the second embodiment is the electrostatic adhesion support member 20 of the first embodiment, further comprising a metal oxide layer 32 between the second resin sheet 24 and the water-repellent film 21.

In this embodiment, the metal oxide layer 32 supporting the water-repellent film 21 may have the same configuration as the metal oxide layer of the water-repellent electrostatic adsorption sheet of the second embodiment. That is, the metal oxide layer 32 is preferably formed to a thickness in the range of 1 nm or more and 50 nm or less, and is made of one or more metal oxides selected from the group consisting of Si, Al, Mg, Ca, Ti, Zn, Zr, Sr, Hf, and Ba.

In accordance with the electrostatic adhesion support member 40 of the second embodiment, the metal oxide layer 32 is used as a support for the water-repellent film 11, thereby increasing the strength of the water-repellent film 11, for example, its resistance to rubbing stress, and realizing an electrostatic adhesion support member 40 that is resistant to repeated wiping stress.

[Method for manufacturing water-repellent electrostatic adhesion sheet: First embodiment]
The method for producing the water-repellent electrostatically adhesive sheet according to the first embodiment of the present invention will be described below. Fig. 3 is a flow chart for explaining the steps of the method for producing the water-repellent electrostatically adhesive sheet according to the first embodiment of the present invention.
3, metal oxide particles 51 and an organic solvent 52 are mixed to prepare a metal oxide particle dispersion 53. A fluorine-based compound 54 containing a fluorine-based functional group component (A) is mixed with this dispersion 53, and water 55 and a catalyst 56 are further mixed to prepare a fluorine-containing metal oxide particle dispersion 57. Meanwhile, a silicon alkoxide 61, an alcohol 62, water 63, and optionally an alkylene group component 64 are mixed, and a catalyst 65 is added to this mixture to prepare a silica sol liquid 66.

A liquid composition 70 for forming a water-repellent film is prepared by mixing this silica sol liquid 66 with alcohol 67 and mixing this mixture with the above-mentioned dispersion liquid 57 of fluorine-containing metal oxide particles. This liquid composition 70 is diluted with alcohol 71 to prepare a diluted liquid 72. This diluted liquid is then formed into a film of a predetermined thickness on one side of a resin sheet (first resin sheet) 12, for example, by a spin coating method. Thereafter, the alcohol 71 is evaporated using a drying device or the like, thereby producing a water-repellent electrostatic adsorption sheet 10 in which a water-repellent film 11 is formed into a predetermined thickness on one side of the resin sheet (first resin sheet) 12.

The procedure for producing the water-repellent film-forming liquid composition for forming the water-repellent film will be described in detail below.
(Preparation of Metal Oxide Particle Dispersion)
First, the metal oxide particles are dispersed in an organic solvent to prepare a dispersion liquid of the metal oxide particles. Examples of the organic solvent include methanol, ethanol, isopropanol (hereinafter sometimes referred to as IPA), tetrahydrofuran, hexane, chloroform, toluene, ethyl acetate, dimethyl sulfoxide (DMSO), dimethylformamide (DMF), acetone, and fluorine-based solvents. Among these, alcohols such as methanol, ethanol, and isopropanol, which have a boiling point of less than 120°C and a carbon number of 1 to 4, are particularly preferred. Examples of the metal oxide particles include particles of SiO ₂ , Al ₂ O ₃ , MgO, CaO, TiO ₂ , ZnO, and ZrO ₂ , mixed particles thereof, and composite oxide particles.

(Preparation of Fluorine-Containing Metal Oxide Particle Dispersion)
Next, a fluorine-based compound containing a fluorine-based functional group component represented by the above formula (1) or (2) is added to the prepared dispersion of metal oxide particles to synthesize a nanocomposite material of the metal oxide particles and the fluorine-based functional group component. To further promote the reaction, water and a catalyst are added. This allows the preparation of a dispersion of fluorine-containing metal oxide particles.

The above-mentioned catalysts include organic acids, inorganic acids, and titanium compounds. Examples of organic acids include formic acid and oxalic acid. Examples of inorganic acids include hydrochloric acid, nitric acid, and phosphoric acid. Examples of titanium compounds include titanium tetrapropoxide, titanium tetrabutoxide, titanium tetraisopropoxide, and titanium lactate. The catalysts are not limited to the above. As the water, it is preferable to use ion-exchanged water or pure water to prevent the inclusion of impurities.

The fluorine-based compound containing a fluorine-based functional group component is represented by the following general formula (3) or formula (4). More specifically, the perfluoroether group in formula (3) or formula (4) can include the perfluoroether structures represented by the following formulas (5) to (13).

In addition, examples of X in the above formulas (3) and (4) include structures shown in the following formulas (14) to (18). Note that the following formula (14) shows an example containing an ether bond, the following formula (15) an ester bond, the following formula (16) an amide bond, the following formula (17) a urethane bond, and the following formula (18) a sulfonamide bond.

In the above formulas (14) to (18), ^R2 and ^R3 are hydrocarbon groups having 0 to 10 carbon atoms, and ^R4 is a hydrogen atom or a hydrocarbon group having 1 to 6 carbon atoms. Examples of the hydrocarbon group for ^R3 include alkylene groups such as a methylene group and an ethylene group, and examples of the hydrocarbon group for ^R4 include alkyl groups such as a methyl group and an ethyl group, as well as a phenyl group.

In the above formulas (3) and (4), R ¹ may be, for example, a methoxy group or an ethoxy group.

In addition, in the above formulas (3) and (4), Z is not particularly limited as long as it is a hydrolyzable group that can be hydrolyzed to form a Si-O-Si bond. Specific examples of such hydrolyzable groups include alkoxy groups such as methoxy, ethoxy, propoxy, and butoxy groups, aryloxy groups such as phenoxy and naphthoxy groups, aralkyloxy groups such as benzyloxy and phenethyloxy groups, and acyloxy groups such as acetoxy, propionyloxy, butyryloxy, valeryloxy, pivaloyloxy, and benzoyloxy groups. Among these, it is preferable to apply a methoxy or ethoxy group.

Specific examples of fluorine-based compounds containing a fluorine-based functional group component having a perfluoroether structure represented by formula (3) or (4) above include structures represented by formulas (19) to (27) below. In formulas (19) to (27) below, R is a methyl group or an ethyl group.

As described above, the fluorine-based compound contained in the water-repellent film-forming liquid composition of this embodiment has a perfluoroether group in which multiple short-chain perfluoroalkyl groups and perfluoroalkylene groups with a carbon number of 6 or less are bonded to an oxygen atom in the molecule, and since the fluorine content in the molecule is high, it can impart excellent water repellency to the formed film. At the same time, it can also impart oil repellency.

(Preparation of Silica Sol Liquid)
First, a mixed solution is prepared by mixing tetramethoxysilane or tetraethoxysilane as a silicon alkoxide, an alcohol having a boiling point of less than 120°C and a carbon number in the range of 1 to 4, and water. At this time, an epoxy group-containing silane, which is an alkylene group component, may be mixed together. Specific examples of this silicon alkoxide include tetramethoxysilane and its oligomers, and tetraethoxysilane and its oligomers. For example, in order to obtain a highly durable water- and oil-repellent film, it is preferable to use tetramethoxysilane, while in order to avoid methanol generated during hydrolysis, it is preferable to use tetraethoxysilane.

Specific examples of the epoxy group-containing silane that is the alkylene group component include 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, and polyfunctional epoxysilane. The alkylene group component is contained in an amount of 1% to 40% by mass, preferably 2.5% to 20% by mass, based on the total mass of the silicon alkoxide and the alkylene group component. If the alkylene group component is less than the lower limit of 1% by mass, when a film is formed on a substrate that does not contain hydroxyl groups, the adhesion to the substrate becomes insufficient. If the amount exceeds the upper limit of 40% by mass, the durability of the formed film decreases.

If the epoxy group-containing silane is included so that the alkylene group component is in the above-mentioned range of 1% by mass to 40% by mass, the epoxy group also opens during the hydrolysis polymerization process and contributes to the polymerization, thereby improving the leveling property during the drying process and making the film thickness uniform. If the substrate contains a hydrophilic group, the content of the alkylene group component may be very small or may be zero. On the other hand, if the substrate does not contain a hydrophilic group, it is preferable that the alkylene group component is included in the silica sol (C) at 0.5% by mass to 20% by mass.

The alcohols having 1 to 4 carbon atoms and a boiling point of less than 120°C include the alcohols mentioned above. Methanol or ethanol are particularly preferred because these alcohols are easily mixed with silicon alkoxides. As the water, it is preferable to use ion-exchanged water or pure water to prevent the inclusion of impurities. A mixture is prepared by adding an alcohol having 1 to 4 carbon atoms and water to the silicon alkoxide, or to the silicon alkoxide and epoxy group-containing silane, and stirring for 5 to 20 minutes at a temperature of 10°C to 30°C.

A catalyst is added to the mixture prepared above and mixed. Examples of this catalyst include organic acids, inorganic acids, and titanium compounds. At this time, the liquid temperature is preferably kept at 30°C to 80°C, and the mixture is stirred for preferably 1 hour to 24 hours. This prepares a silica sol liquid. For the next step, alcohol is added to the silica sol liquid and mixed.

The silica sol liquid to which the alcohol has been added contains 2% to 50% by mass of silicon alkoxide, 20% to 98% by mass of alcohol having 1 to 4 carbon atoms, 0.1% to 40% by mass of water, and 0.01% to 5% by mass of the catalyst. When an epoxy group-containing silane, which is an alkylene group component, is mixed, the content of the epoxy group-containing silane is up to 30% by mass.

The proportion of alcohols with carbon numbers between 1 and 4 is limited to the above range because if the proportion of alcohol is below the lower limit, the silicon alkoxide will not dissolve in the solution and will separate, and the reaction solution will be prone to gelling during the hydrolysis reaction of the silicon alkoxide; on the other hand, if the proportion is above the upper limit, the amount of water and catalyst required for hydrolysis will be relatively small, causing the reactivity of the hydrolysis to decrease, polymerization to not proceed, and the adhesion of the film to decrease.

The water ratio is limited to the above range because below the lower limit, the hydrolysis rate slows down, polymerization does not proceed, and the adhesion of the water- and oil-repellent film becomes insufficient, while above the upper limit, the reaction liquid gels during the hydrolysis reaction, and there is too much water, so the silicon alkoxide compound does not dissolve in the alcohol aqueous solution, resulting in separation.

The _SiO2 concentration ( _SiO2 content) in the silica sol is preferably 1% by mass to 40% by mass. If the _SiO2 concentration is less than the lower limit, polymerization is insufficient, and the adhesion of the film is reduced and cracks are likely to occur, while if the SiO2 concentration exceeds the upper limit, the proportion of water becomes relatively high, silicon alkoxide does not dissolve, and the reaction liquid gels.

The organic acid, inorganic acid or titanium compound functions as a catalyst to promote the hydrolysis reaction. Examples of organic acids include formic acid and oxalic acid, examples of inorganic acids include hydrochloric acid, nitric acid and phosphoric acid, and examples of titanium compounds include titanium tetrapropoxide, titanium tetrabutoxide, titanium tetraisopropoxide and titanium lactate. The catalyst is not limited to the above. The proportion of the above catalyst is limited to the above range because below the lower limit, the reactivity is poor and polymerization is insufficient, so that a film is not formed, whereas above the upper limit, there is no effect on reactivity, but problems such as corrosion of the substrate due to residual acid occur.

(Liquid composition for forming water-repellent film)
The water-repellent film-forming liquid composition of the present embodiment is produced according to the above-mentioned procedure, and contains metal oxide particles having a fluorine-based functional group component bonded thereto, silica sol, and a solvent. The fluorine-based functional group component has a perfluoroether structure represented by the above-mentioned general formula (1) or formula (2), and is contained in the water-repellent film-forming liquid composition in an amount of 0.5% by mass to 25% by mass.

The above solvent may be a mixed solvent of water and an alcohol having 1 to 4 carbon atoms, or a mixed solvent of water, an alcohol having 1 to 4 carbon atoms, and an organic solvent other than the above alcohol. Specific examples of perfluoroether structures include the structures shown by the above formulas (19) to (27).

Since the liquid composition for forming a water-repellent film of this embodiment contains silica sol liquid as a main component, the water-repellent film 11 has excellent adhesion to the resin sheet (first resin sheet) 12, and is strong enough to not peel off. In addition, since the liquid composition for forming a water-repellent film contains a fluorine-based functional group component with a perfluoroether structure represented by the above general formula (1) or formula (2), the obtained water-repellent film 11 has a high water-repellent effect.

[Method for manufacturing water-repellent electrostatic adsorption sheet: Second embodiment]
Next, a method for producing a water-repellent electrostatically adhesive sheet according to a second embodiment of the present invention will be described. Note that a description of the same configuration as in the first embodiment will be omitted.

In the method for manufacturing the water-repellent electrostatic adsorption sheet of the second embodiment, a metal oxide layer 32 having the same configuration as the water-repellent electrostatic adsorption sheet of the second embodiment is formed on one side of a resin sheet (first resin sheet) 12. The process for forming the metal oxide layer 32 may be, for example, a process in which the metal oxide constituting the metal oxide layer 32 is used as a target, and the target metal oxide is deposited on one side of the resin sheet 12 by a sputtering method to form the metal oxide layer 32.

Alternatively, the metal oxide layer 32 may be formed by a deposition method in which the metal oxide constituting the metal oxide layer 32 is melted, evaporated, or sublimated, and then adhered to one side of the resin sheet 12.

The method for forming the metal oxide layer 32 is not limited to the sputtering method or vapor deposition method described above, and any method that can form a metal oxide layer, such as forming a metal oxide layer by thermal oxidation of a metal film, may be used, and is not limited thereto.

In this embodiment, a quartz (SiO ₂ ) target is used to form the metal oxide layer 32 made of a quartz film on one surface of the resin sheet 12 by sputtering.
The metal oxide layer 32 may be formed to have a thickness in the range of 1 nm or more and 50 nm or less.

After this, an alcohol diluted solution 72 of the water-repellent film-forming liquid composition 70 similar to that of the first embodiment is applied to the surface of the metal oxide layer 32, for example by spin coating, and the alcohol 71 is evaporated, thereby producing the water-repellent electrostatic adsorption sheet 30 of the second embodiment, in which the water-repellent film 11 is formed to a predetermined thickness on one side of the resin sheet (first resin sheet) 12 via the metal oxide layer 32.

Although the embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the gist of the invention. These embodiments and their modifications are within the scope of the invention and its equivalents as set forth in the claims, as well as the scope and gist of the invention.

The effects of the water-repellent electrostatically adhesive sheet of the present invention were examined below.
First, a base solution was prepared as follows.
<Synthesis Example 1>
A flask was charged with 50.00 g of an IPA dispersion of SiO ₂ having an average particle size of 12 nm (IPA-ST, manufactured by Nissan Chemical Industries, adjusted to a SiO ₂ concentration of 15%), 0.83 g of a fluorine-based compound represented by formula (19), 13.24 g of methyl silicate (manufactured by Mitsubishi Chemical Corporation), which is a polymer of tetraethoxysilane, and 31.87 g of ethanol (manufactured by Japan Alcohol Industry Co., Ltd.), and 4.05 g of pure water was added and mixed, and then 0.01 g of 35% hydrochloric acid (manufactured by Fujifilm Wako Pure Chemical Industries Co., Ltd.) was added and mixed for 4 hours in an environment of 60 ° C. to obtain a base solution of Synthesis Example 1.
The average particle size was determined by measuring particle size by dynamic light scattering (DLS) using a particle size distribution meter (manufactured by Otsuka Electronics Co., Ltd., product name "nanoSAQLA").

<Synthesis Example 2>
A flask containing 50.00 g of an IPA dispersion of SiO ₂ having an average particle size of 45 nm (IPA-ST-L, manufactured by Nissan Chemical Industries, adjusted to a SiO ₂ concentration of 15%), 1.17 g of a fluorine-based compound represented by the formula (20), 23.04 g of tetraethyl silicate (manufactured by FUJIFILM Wako Pure Chemical Industries), and 17.83 g of ethanol (manufactured by Japan Alcohol Industry Co., Ltd.) was charged with 7.96 g of pure water, and then mixed. Then, 0.01 g of 60% nitric acid (manufactured by FUJIFILM Wako Pure Chemical Industries Co., Ltd.) was added and mixed in an environment of 40 ° C. for 2 hours to obtain a base solution of Synthesis Example 2.

<Synthesis Example 3>
A flask was charged with 80.00 g of an IPA dispersion of SiO ₂ having an average particle size of 80 nm (IPA-ST-ZL, manufactured by Nissan Chemical Industries Co., Ltd., adjusted to a SiO ₂ concentration of 15%), 0.33 g of a fluorine-based compound represented by formula (21), 5.29 g of methyl silicate (manufactured by Mitsubishi Chemical Corporation), which is a polymer of tetraethoxysilane, and 12.72 g of ethanol (manufactured by Japan Alcohol Industry Co., Ltd.), and 1.62 g of pure water was added and mixed, and then 0.03 g of acetic acid (manufactured by Fujifilm Wako Pure Chemical Industries Co., Ltd.) was added and mixed for 4 hours in an environment of 60 ° C. to obtain a base liquid of Synthesis Example 3.

<Synthesis Example 4>
After preparing TiO ₂ (model number P25, manufactured by Nippon Aerosil Co., Ltd.) having an average particle size of 28 nm in IPA dispersion (TiO ₂ concentration adjusted to 15%), 30.00 g of TiO ₂ dispersion, 4.17 g of the fluorine-based compound represented by formula (22), 11.76 g of methyl silicate (manufactured by Mitsubishi Chemical Corporation), which is a polymer of tetraethoxysilane, 0.48 g of silane coupling material (KBM-5103, manufactured by Shin-Etsu Chemical Co., Ltd.), and 49.94 g of ethanol (manufactured by Japan Alcohol Industry Co., Ltd.) were added to a flask, 3.60 g of pure water was added and mixed, and then 0.05 g of tetraisopropoxytitanium (manufactured by Fujifilm Wako Pure Chemical Industries Co., Ltd.) was added and mixed in an environment of 60 ° C. for 4 hours to obtain a base liquid of Synthesis Example 4.

<Synthesis Example 5>
_ZrO2 (manufactured by Daiichi Kigenso Kagaku Kogyo Co., Ltd.) with an average particle size of 35 nm was made into an IPA dispersion ( _ZrO2 concentration adjusted to 15%), and then 50.00 g of _ZrO2 dispersion, 0.83 g of a fluorine-based compound represented by formula (27), 11.76 g of methyl silicate (manufactured by Mitsubishi Chemical Corporation), which is a polymer of tetraethoxysilane, 0.61 g of a silane coupling agent (KBE9007N, manufactured by Shin-Etsu Chemical Co., Ltd.), and 33.18 g of ethanol (manufactured by Japan Alcohol Industry Co., Ltd.) were added to a flask, and 3.60 g of pure water was added and mixed, and then 0.01 g of 60% nitric acid (manufactured by Fujifilm Wako Pure Chemical Industries Co., Ltd.) was added, and the mixture was mixed in an environment of 60 ° C. for 4 hours to obtain a base solution of synthesis example 5.

<Synthesis Example 6>
_BaTiO3 (manufactured by Kyoritsu Material Co., Ltd.) with an average particle size of 200 nm was made into an IPA dispersion ( _BaTiO3 concentration adjusted to 15%), and then 8.05 g of pure water was added to a flask containing 10.00 g of _BaTiO3 dispersion, 0.08 g of a fluorine-based compound represented by formula (27), 26.32 g of methyl silicate (manufactured by Mitsubishi Chemical Co., Ltd.), which is a polymer of tetraethoxysilane, and 55.53 g of ethanol (manufactured by Japan Alcohol Industry Co., Ltd.), and mixed. Then, 0.01 g of 60% nitric acid (manufactured by Fujifilm Wako Pure Chemical Industries Co., Ltd.) was added and mixed for 4 hours in an environment of 60 ° C. to obtain a base solution of Synthesis Example 6.

<Synthesis Example 7>
A flask containing 50.00 g of an IPA dispersion of SiO ₂ having an average particle size of 15 nm (IPA-ST, manufactured by Nissan Chemical Industries Co., Ltd., adjusted to a SiO ₂ concentration of 15%), 14.71 g of methyl silicate (manufactured by Mitsubishi Chemical Corporation), which is a polymer of tetraethoxysilane, and 30.79 g of ethanol (manufactured by Japan Alcohol Industry Co., Ltd.) was added with 4.50 g of pure water and mixed, after which 0.01 g of 60% nitric acid (manufactured by Fujifilm Wako Pure Chemical Industries Co., Ltd.) was added and mixed in an environment of 60 ° C. for 4 hours to obtain a base solution of Synthesis Example 7. In addition, no fluorine-based compounds were included.

<Synthesis Example 8>
A flask was charged with 50.00 g of an IPA dispersion of SiO ₂ having an average particle size of 15 nm (IPA-ST, manufactured by Nissan Chemical Industries, adjusted to a SiO ₂ concentration of 15%), 5.00 g of a fluorine-based compound represented by formula (19), 5.88 g of methyl silicate (manufactured by Mitsubishi Chemical Corporation), which is a polymer of tetraethoxysilane, and 37.31 g of ethanol (manufactured by Japan Alcohol Industry Co., Ltd.), and 1.80 g of pure water was added and mixed, and then 0.01 g of 60% nitric acid (manufactured by Fujifilm Wako Pure Chemical Industries Co., Ltd.) was added and mixed for 4 hours in an environment of 60 ° C. to obtain a base solution of Synthesis Example 8.

<Synthesis Example 9>
SiO ₂ (manufactured by Nippon Aerosil Co., Ltd.) with an average particle size of 6 nm was made into an IPA dispersion (SiO ₂ concentration adjusted to 15%), and then 50.00 g of SiO ₂ dispersion, 0.83 g of a fluorine-based compound represented by formula (27), 13.24 g of methyl silicate (manufactured by Mitsubishi Chemical Co., Ltd.), which is a polymer of tetraethoxysilane, and 31.87 g of ethanol (manufactured by Japan Alcohol Industry Co., Ltd.) were added to a flask, 4.05 g of pure water was added and mixed, and then 0.01 g of 60% nitric acid (manufactured by Fujifilm Wako Pure Chemical Industries Co., Ltd.) was added and mixed in an environment of 60 ° C. for 4 hours to obtain a base solution of Synthesis Example 9.

(Verification Example 1)
Example 1
12.2 g of industrial alcohol (AP-7, manufactured by Japan Alcohol Industry Co., Ltd.), 0.3 g of diacetone alcohol, and 1.8 g of isopropyl glycol were added to and mixed with 0.6 g of the obtained base liquid of Synthesis Example 1 to obtain a coating liquid of Example 1. This coating liquid was formed into a film on a polyimide substrate (thickness 50 μm) by spin coating (rotation speed 500 rpm), and dried in the air at 150° C. for 4 hours, to obtain a water-repellent electrostatically adhesive sheet of Example 1 on which a water-repellent film was formed.

Example 2
12.2 g of industrial alcohol (AP-7, manufactured by Japan Alcohol Industry Co., Ltd.), 0.3 g of diacetone alcohol, and 1.8 g of isopropyl glycol were added to and mixed with 0.6 g of the obtained base liquid of Synthesis Example 2 to obtain a coating liquid of Example 2. This coating liquid was formed into a film on a polyimide substrate (thickness 50 μm) by spin coating (rotation speed 500 rpm), and dried in the air at 150° C. for 4 hours to obtain a water-repellent electrostatically adhesive sheet of Example 2 on which a water-repellent film was formed.

Example 3
12.2 g of industrial alcohol (AP-7, manufactured by Japan Alcohol Industry Co., Ltd.), 0.3 g of diacetone alcohol, and 1.8 g of isopropyl glycol were added to and mixed with 0.6 g of the obtained base liquid of Synthesis Example 3 to obtain a coating liquid of Example 3. This coating liquid was formed into a film on a polyimide substrate (thickness 50 μm) by spin coating (rotation speed 500 rpm), and dried at 150° C. for 4 hours in the air, to obtain a water-repellent electrostatic adsorption sheet of Example 3 on which a water-repellent film was formed.

Example 4
12.2 g of industrial alcohol (AP-7, manufactured by Japan Alcohol Industry Co., Ltd.), 0.3 g of diacetone alcohol, and 1.8 g of isopropyl glycol were added to and mixed with 0.6 g of the obtained base liquid of Synthesis Example 4 to obtain a coating liquid of Example 4. This coating liquid was formed into a film on a polyimide substrate (thickness 50 μm) by spin coating (rotation speed 500 rpm), and dried in the air at 150° C. for 4 hours to obtain a water-repellent electrostatic adsorption sheet of Example 4 on which a water-repellent film was formed.

Example 5
12.2 g of industrial alcohol (AP-7, manufactured by Japan Alcohol Industry Co., Ltd.), 0.3 g of diacetone alcohol, and 1.8 g of isopropyl glycol were added to and mixed with 0.6 g of the obtained base liquid of Synthesis Example 5 to obtain a coating liquid of Example 5. This coating liquid was formed into a film on a polyimide substrate (thickness 50 μm) by spin coating (rotation speed 500 rpm), and dried at 150° C. for 4 hours in the air, to obtain a water-repellent electrostatic adsorption sheet of Example 5 on which a water-repellent film was formed.

Example 6
12.2 g of industrial alcohol (AP-7, manufactured by Japan Alcohol Industry Co., Ltd.), 0.3 g of diacetone alcohol, and 1.8 g of isopropyl glycol were added to and mixed with 0.6 g of the obtained base liquid of Synthesis Example 6 to obtain a coating liquid of Example 6. This coating liquid was formed into a film on a polyimide substrate (thickness 50 μm) by spin coating (rotation speed 500 rpm), and dried in the air at 150° C. for 4 hours to obtain a water-repellent electrostatic adsorption sheet of Example 6 on which a water-repellent film was formed.

Example 7
11.5 g of industrial alcohol (AP-7, manufactured by Japan Alcohol Industry Co., Ltd.), 0.3 g of diacetone alcohol, and 1.8 g of isopropyl glycol were added to and mixed with 1.5 g of the obtained base liquid of Synthesis Example 2 to obtain a coating liquid of Example 7. This coating liquid was formed into a film on a polyimide substrate (thickness 50 μm) by spin coating (rotation speed 500 rpm), and dried at 150° C. for 4 hours in the air, to obtain a water-repellent electrostatic adsorption sheet of Example 7 on which a water-repellent film was formed.

Example 8
12.6 g of industrial alcohol (AP-7, manufactured by Japan Alcohol Industry Co., Ltd.), 0.3 g of diacetone alcohol, and 1.9 g of isopropyl glycol were added to and mixed with 0.2 g of the obtained base liquid of Synthesis Example 2 to obtain a coating liquid of Example 8. This coating liquid was formed into a film on a polyimide substrate (thickness 50 μm) by spin coating (rotation speed 500 rpm), and dried in the air at 150° C. for 4 hours to obtain a water-repellent electrostatic adsorption sheet of Example 8 having a water-repellent film formed thereon.

<Comparative Example 1>
12.2 g of industrial alcohol (AP-7, manufactured by Japan Alcohol Industry Co., Ltd.), 0.3 g of diacetone alcohol, and 1.8 g of isopropyl glycol were added to and mixed with 0.6 g of the obtained base liquid of Synthesis Example 7 to obtain a coating liquid of Comparative Example 1. This coating liquid was formed into a film on a polyimide substrate (thickness 50 μm) by spin coating (rotation speed 500 rpm), and dried in the air at 150° C. for 4 hours to obtain a water-repellent electrostatic adsorption sheet of Comparative Example 1 on which a water-repellent film was formed.

<Comparative Example 2>
12.2 g of industrial alcohol (AP-7, manufactured by Japan Alcohol Industry Co., Ltd.), 0.3 g of diacetone alcohol, and 1.8 g of isopropyl glycol were added to and mixed with 0.6 g of the base liquid obtained in Synthesis Example 8 to obtain a coating liquid of Comparative Example 2. This coating liquid was formed into a film on a polyimide substrate (thickness 50 μm) by spin coating (rotation speed 500 rpm), and dried in the air at 150° C. for 4 hours to obtain a water-repellent electrostatic adsorption sheet of Comparative Example 2 on which a water-repellent film was formed.

<Comparative Example 3>
12.2 g of industrial alcohol (AP-7, manufactured by Japan Alcohol Industry Co., Ltd.), 0.3 g of diacetone alcohol, and 1.8 g of isopropyl glycol were added to and mixed with 0.6 g of the base liquid of Synthesis Example 9 obtained, to obtain a coating liquid of Comparative Example 3. This coating liquid was formed into a film on a polyimide substrate (thickness 50 μm) by spin coating (rotation speed 500 rpm), and dried in the air at 150° C. for 4 hours, to obtain a water-repellent electrostatic adsorption sheet of Comparative Example 3 on which a water-repellent film was formed.

<Comparative Example 4>
11.1 g of industrial alcohol (AP-7, manufactured by Japan Alcohol Industry Co., Ltd.), 0.3 g of diacetone alcohol, and 1.7 g of isopropyl glycol were added to and mixed with 2.0 g of the obtained base liquid of Synthesis Example 2 to obtain a coating liquid of Comparative Example 4. This coating liquid was formed into a film on a polyimide substrate (thickness 50 μm) by spin coating (rotation speed 500 rpm), and dried in the air at 150° C. for 4 hours to obtain a water-repellent electrostatic adsorption sheet of Comparative Example 4 on which a water-repellent film was formed.

<Comparative Example 5>
12.7 g of industrial alcohol (AP-7, manufactured by Japan Alcohol Industry Co., Ltd.), 0.3 g of diacetone alcohol, and 1.9 g of isopropyl glycol were added to and mixed with 0.1 g of the obtained base liquid of Synthesis Example 2 to obtain a coating liquid of Comparative Example 5. This coating liquid was formed into a film on a polyimide substrate (thickness 50 μm) by spin coating (rotation speed 500 rpm), and dried in the air at 150° C. for 4 hours to obtain a water-repellent electrostatic adsorption sheet of Comparative Example 5 on which a water-repellent film was formed.

The water-repellent electrostatic adsorption sheets (samples) of Examples 1 to 8 and Comparative Examples 1 to 5 were measured for the contact angle with water (water repellency), contact angle with oil (hexadecane) (oil repellency), relative dielectric constant, surface resistivity, electrostatic chuck action, film strength, and adsorption resistance when immersed in water.

<Contact angle with respect to water>
In an environment at an air temperature of 25° C., 2 μL of pure water was dropped onto the surface of each sample, and the contact angle was measured after 1 second.

<Contact angle to oil>
In an environment at an air temperature of 25° C., 2 μL of hexadecane was dropped onto the surface of each sample, and the contact angle was measured after 1 second.

<Dielectric constant>
The dielectric constant was measured by forming a film (sample) on a substrate made of SUS304 using each of the sample solutions of Examples 1 to 8 and Comparative Examples 1 to 5, and measuring the dielectric constant of the surface of each sample by a parallel plate method using a dielectric constant measuring device (Material Analyzer 4291B: manufactured by Keysight Corporation).

<Surface resistivity>
The surface resistivity of each sample was measured using a Hiresta (manufactured by Nitto Seiko Analytech Co., Ltd.) When the surface resistivity exceeded 10 ⁻¹⁵ Ω/sq, it was marked as “OVER”.

<Electrostatic action test>
Using an electrostatic chuck device (manufactured by Tsukuba Seiko Co., Ltd.), each sample was placed on a wafer supporter, the surface was charged, and then the silicon wafer was placed on it. The adhesion state of the silicon wafer was then checked with a tentacle. If the silicon wafer was adhered, it was judged as "good" and if it was not adhered, it was judged as "bad".
Electrostatic chuck device output: 1 kW
Wafer supporter size: 150 mm square Polyimide film size: length 150 x width 150 x thickness 0.05 (mm)
Silicon wafer size: 4-inch wafer

<Water immersion>
The samples that showed a "good" adhesion state in the electrostatic action test were immersed in a water tank filled with pure water for 5 minutes to check whether water had penetrated between the water-repellent film and the silicon wafer.

<Film strength>
Using a static and dynamic friction tester (TL201Tt, manufactured by Trinity Lab Co., Ltd.), the contact was reciprocated 10 times while applying a specified vertical load, and the water contact angle was measured by visually checking whether the water-repellent film had peeled off. If the change was within 10% of the initial value, it was rated as "good," and if it changed by more than 10%, it was rated as "bad."
Measurement condition:
Travel distance: 30 mm
Vertical load: 500g
・Travel speed: 50 mm/sec ・Contact: 5 mm x 15 mm (neoprene rubber)

The measurement results of the above verification example 1 are summarized in Table 1. Figures 4 and 5 show the appearance (schematic example) of the water immersion test of the example of the present invention (with water-repellent coating) and the comparative example (without water-repellent coating, polyimide film relative dielectric constant of 3.5, water contact angle of 77°), as well as the results.

According to the results in Table 1, the water-repellent electrostatic adsorption sheets (samples) of Examples 1 to 8 all exhibited favorable results in terms of the contact angle with water (water repellency), the contact angle with oil (hexadecane) (oil repellency), the relative dielectric constant, the surface resistivity, the electrostatic chuck action, the film strength, and the adsorption resistance when immersed in water.
On the other hand, the water-repellent electrostatic adsorption sheets (samples) of Comparative Examples 1 to 5 did not satisfy the criteria in at least one of the above-mentioned items.

(Verification Example 2)
Example 11
Using a sputtering device (model number SPH-2307: manufactured by Showa Vacuum Co., Ltd.), sputtering was performed on a polyimide substrate (thickness 50 μm) using a Si target, and a SiO ₂ film (metal oxide layer) was formed in an oxygen gas atmosphere. The film formation conditions were pulse DC current, output 500 W, argon flow rate 30 sccm, and oxygen gas flow rate 20 sccm. As a result, a polyimide substrate on which a SiO ₂ film with a film thickness of 1 nm was formed was obtained. Then, on this SiO ₂ film, the coating liquid used in Example 1 of Verification Example 1 was formed by spin coating (rotation speed 500 rpm), and dried in the air at 150 ° C. for 4 hours, and a water-repellent electrostatic adsorption sheet of Example 11 in which a water-repellent film was formed by overlapping it on the metal oxide layer was obtained. The thickness of the metal oxide layer was measured by reflectance spectroscopy using a high-precision non-contact film thickness meter (model name "FR-ES" manufactured by Theta Metrisis Co., Ltd.).

Example 12
A water-repellent electrostatic adsorption sheet of Example 12 was obtained under the same conditions as in Example 11, except that a _SiO2 film with a thickness of 10 nm was formed on the polyimide substrate and that the coating liquid used in Example 2 of Verification Example 1 was used to overlay the metal oxide layer to form a water-repellent film.

Example 13
A water-repellent electrostatic adsorption sheet of Example 13 was obtained under the same conditions as in Example 11, except that a _SiO2 film with a thickness of 50 nm was formed on the polyimide substrate and that the coating liquid used in Example 3 of Verification Example 1 was used to overlay the metal oxide layer to form a water-repellent film.

<Example 14>
A water-repellent electrostatic adsorption sheet of Example 14 was obtained under the same conditions as in Example 11, except that a _ZrO2 film with a thickness of 10 nm was formed on a polyimide substrate using a Zr target, and that the coating liquid used in Example 4 of Verification Example 1 was used to overlay the metal oxide layer to form a water-repellent film.

Example 15
A water-repellent electrostatic adsorption sheet of Example 15 was obtained under the same conditions as in Example 11, except that a _TiO2 film with a thickness of 10 nm was formed on the polyimide substrate using a Ti target, and that the coating liquid used in Example 5 of Verification Example 1 was used to overlay the metal oxide layer to form a water-repellent film.

<Example 16>
A water-repellent electrostatic adsorption sheet of Example 16 was obtained under the same conditions as in Example 11, except that a BaTiO film with a thickness of 10 nm was formed on a polyimide substrate using a Ti—Ba target, and that the coating liquid used in Example 6 of Verification Example 1 was used to overlay a water-repellent film on the metal oxide layer.

<Example 17>
A water-repellent _{electrostatic} adsorption sheet of Example 17 was obtained under the same conditions as in Example 11, except that an _Al2O3 film with a thickness of 10 nm was formed on the polyimide substrate using an Al target, and a water-repellent film was formed by overlapping the metal oxide layer using the coating liquid used in Example 2 of Verification Example 1.

<Example 18>
The water-repellent electrostatic adsorption sheet of Example 18 was obtained under the same conditions as in Example 11, except that a 10 nm-thick MgO film was formed on the polyimide substrate using an Mg target, and a water-repellent film was formed by overlaying the metal oxide layer using the coating liquid used in Example 2 of Verification Example 1.

<Comparative Example 11>
Using a sputtering device (model number SPH-2307: manufactured by Showa Vacuum Co., Ltd.), sputtering was performed on a polyimide substrate (thickness 50 μm) using a Si target, and a SiO ₂ film (metal oxide layer) was formed in an oxygen gas atmosphere. The film formation conditions were pulse DC current, output 500 W, argon flow rate 30 sccm, and oxygen gas flow rate 20 sccm. As a result, a polyimide substrate on which a SiO ₂ film with a film thickness of 1 nm was formed was obtained. Then, on this SiO ₂ film, the coating liquid used in Comparative Example 1 of Verification Example 1 was spin-coated (rotation speed 500 rpm) to form a film, and dried in the air at 150 ° C. for 4 hours, and a water-repellent electrostatic adsorption sheet of Comparative Example 11 in which a water-repellent film was formed by overlapping it on the metal oxide layer was obtained.

<Comparative Example 12>
A water-repellent electrostatic adsorption sheet of Comparative Example 12 was obtained under the same conditions as Comparative Example 11, except that the coating liquid used in Comparative Example 2 of Verification Example 1 was used to overlay a metal oxide layer to form a water-repellent film.

<Comparative Example 13>
A water-repellent electrostatic adsorption sheet of Comparative Example 13 was obtained under the same conditions as Comparative Example 11, except that the coating liquid used in Comparative Example 3 of Verification Example 1 was used to overlay a water-repellent film on the metal oxide layer.

<Comparative Example 14>
A water-repellent electrostatic adsorption sheet of Comparative Example 14 was obtained under the same conditions as Comparative Example 11, except that a metal oxide layer was not formed on the polyimide substrate and that the base liquid of Synthesis Example 2 of Verification Example 1 was used.

<Comparative Example 15>
A water-repellent electrostatic adsorption sheet of Comparative Example 15 was obtained under the same conditions as Comparative Example 11, except that a water-repellent film was formed on the metal oxide layer (SiO ₂ ) using the coating liquid of Comparative Example 15, which was prepared by adding 12.2 g of industrial alcohol (AP-7, manufactured by Japan Alcohol Industry Co., Ltd.) to 0.1 g of the base liquid of Synthesis Example 2, 0.9 g of diacetone alcohol, and 1.8 g of isopropyl glycol and mixing them.

<Example 16>
A water-repellent electrostatic adsorption sheet of Comparative Example 16 was obtained under the same conditions as in Comparative Example 15, except that a _SiO2 film with a thickness of 75 nm was formed on the polyimide substrate.

<Wipe resistance>
Using a static and dynamic friction tester (TL201Tt, manufactured by Trinity Lab Co., Ltd.), the contact was reciprocated 500 times while applying a specified vertical load, and the water contact angle was measured by visually checking whether the water-repellent film had peeled off. If the change was within 10% of the initial value, it was rated as "good," and if it changed by more than 10%, it was rated as "bad."
Measurement condition:
Travel distance: 30 mm
Vertical load: 500g
- Travel speed: 60 mm/sec - Contact: Nonwoven fabric (Bencotto: manufactured by Asahi Kasei Corporation) soaked in ethanol, fixed to SUS with a diameter of 25 mm The surface of the water-repellent film of each sample of Examples 11 to 18 and Comparative Examples 11 to 16 was rubbed repeatedly 500 times with the above contact at a load of 100 g/ ^cm2 , and the surface condition of the water-repellent film was observed. Then, the water-repellent film was visually checked for peeling, and if there was no peeling, it was rated as "good", and if at least a part of it was peeled, it was rated as "poor".

The water contact angle, oil contact angle, dielectric constant, surface resistivity, electrostatic action test, and water immersion were performed in the same manner as in Verification Example 1.
The measurement results of the above-mentioned Verification Example 2 are summarized in Table 2.

According to the results in Table 2, the water-repellent electrostatic adsorption sheets (samples) of Examples 11 to 18 all showed good results in terms of contact angle with water (water repellency), contact angle with oil (hexadecane) (oil repellency), relative dielectric constant, surface resistivity, electrostatic chucking action, wiping resistance, and adsorption resistance when immersed in water.
On the other hand, the water-repellent electrostatic adsorption sheets (samples) of Comparative Examples 11 to 16 did not satisfy the criteria in at least one of the above-mentioned items.

By using the water-repellent film of the present invention for electrostatic adsorption, the object to be attracted can be held even in liquid without the electrostatic adsorption being released. In addition, by disposing the water-repellent electrostatic adsorption sheet of the present invention between the electrostatic chuck and the object to be attracted, the electrostatic adsorption state can be maintained even in liquid. Furthermore, with the electrostatic adsorption support member of the present invention, the object to be attracted can be moved while being electrostatically adsorbed, and the electrostatic adsorption state can be maintained even in liquid. Therefore, the present invention has industrial applicability.

REFERENCE SIGNS LIST 1 Electrostatic adsorption device 2 Electrostatic adsorption stage 3 Wafer 5 Electrostatic adsorption device 6 Electrostatic adsorption stage 7 Stage body 10 Water-repellent electrostatic adsorption sheet 11 Water-repellent film 12 Resin sheet (first resin sheet)
20: electrostatic attraction support member 21: water-repellent film 22: dielectric plate 23: electrode film 24: resin sheet (second resin sheet)
30 Water-repellent electrostatic adhesion sheet 32 Metal oxide layer 40 Electrostatic adhesion support member

Claims (12)

A chargeable water-repellent film for use in electrostatic adsorption, comprising:
The water-repellent film has a contact angle with water of 100° or more, a relative dielectric constant of 2.0 or more, and a thickness of 50 nm or more and 2000 nm or less. The water-repellent film comprises metal oxide particles (B) having an average particle size of 10 nm or more and 210 nm or less to which a fluorine-based functional group component (A) containing a perfluoroether structure represented by the following general formula (1) or formula (2) is bonded, and a silica sol (C):
the fluorine-based functional group component (A) is contained in an amount of 0.5% by mass or more and 25% by mass or less when the entire water-repellent film is taken as 100% by mass,
2. The water-repellent film according to claim 1, characterized in that the metal oxide particles (B) are contained in an amount of 10% by mass or more and 80% by mass or less when the entire water-repellent film is taken as 100% by mass.

In the above formula (1) and formula (2), p, q, and r are each the same or different integers of 1 to 6, and may be linear or branched. In addition, in the above formula (1) and formula (2), X is a hydrocarbon group having 2 to 10 carbon atoms, and may contain one or more bonds selected from an ether bond, a CO-NH bond, an O-CO-NH bond, and a sulfonamide bond. Furthermore, in the above formula (1) and formula (2), Y is a silane hydrolyzate or a main component of a silica sol. The water-repellent film according to claim 2, characterized in that the metal oxide particles (B) are one or more oxide particles selected from the group consisting of Si, Al, Mg, Ca, Ti, Zn, Zr, and Ba. A water-repellent electrostatic adsorption sheet disposed between an electrostatic chuck of an electrostatic adsorption device and a substrate that is an object to be adsorbed,
A water-repellent electrostatic adsorption sheet comprising: the water-repellent film according to claim 2; and a first resin sheet supporting the water-repellent film. The water-repellent electrostatic adsorption sheet according to claim 4, characterized in that the first resin sheet contains a polyimide resin. A water-repellent electrostatic adsorption sheet disposed between an electrostatic chuck of an electrostatic adsorption device and a substrate that is an object to be adsorbed,
3. A water-repellent electrostatic adhesion sheet comprising: the water-repellent film according to claim 2; and a metal oxide layer supporting the water-repellent film and having a thickness of 1 nm or more and 50 nm or less. The water-repellent electrostatic adsorption sheet according to claim 6, characterized in that the metal oxide layer is made of one or more metal oxides selected from the group consisting of Si, Al, Mg, Ca, Ti, Zn, Zr, Sr, Hf, and Ba. An electrostatic adsorption support member that is detachably provided on an electrostatic adsorption device,
3. An electrostatic adsorption support member comprising: a dielectric plate; an electrode film formed on one side of the dielectric plate; a second resin sheet arranged on one side of the electrode film; and the water-repellent film described in claim 2 arranged on top of the one side of the second resin sheet. The electrostatic adsorption support member according to claim 8, characterized in that the second resin sheet contains polyimide resin. The electrostatic adsorption support member according to claim 8, characterized in that a metal oxide layer having a thickness of 1 nm or more and 50 nm or less is disposed between the second resin sheet and the water-repellent film to support the water-repellent film. A method for producing the water-repellent electrostatically adhesive sheet according to claim 4, comprising the steps of:
a step of mixing a dispersion of the metal oxide particles having the fluorine-based functional group component (A) bonded thereto with a silica sol to prepare a water-repellent film-forming liquid composition;
forming a diluted solution of the water-repellent film-forming liquid composition on a first resin sheet by spin coating. A method for producing the water-repellent electrostatically adhesive sheet according to claim 6, comprising the steps of:
forming the metal oxide layer on a first resin sheet;
a step of mixing a dispersion of the metal oxide particles having the fluorine-based functional group component (A) bonded thereto with a silica sol to prepare a water-repellent film-forming liquid composition;
forming a dilute solution of the water-repellent film-forming liquid composition on the metal oxide layer by spin coating.

Images