Electrostatic Adsorption Tools and Surface Processing Methods

Abstract

This invention provides an electrostatic adsorption tool that can maintain the adsorption of thin objects for a long time in a humid environment. An electrostatic adsorption tool A1 includes an electrostatic adsorption force generating member 30. This member 30 has electrode components 302 and 303 embedded inside an electrically insulating layer 301. The thin object 10 is electrostatically adsorbed by applying a voltage to the electrode components 302 and 303. The electrostatic adsorption force generating member 30 has at least a first water-repellent insulating layer 305 of water-repellent material on the adsorption surface of the adsorbed thin object 10.

Description

Electrostatic Adsorption Tools and Surface Processing Methods This invention relates to an electrostatic adsorption tool for adsorbing and retaining an object, and a surface processing method for processing the surface of an object in an electrostatic adsorption state. Previously, electrostatic chucks utilizing Coulomb force were known to include a ceramic substrate, an insulating layer formed on one main surface of the ceramic substrate and having an adsorption surface for adsorbing an insulating substrate, and a pair of electrodes formed between the ceramic substrate and the insulating layer. The insulating layer is a sintered ceramic body identical to the ceramic substrate, and its thickness is 0.001 mm or more and 0.1 mm or less. The distance between the pair of electrodes is 0.3 mm or more and 2.5 mm or less (see, for example, Patent Document 1). [Prior Art Documents] [Patent Documents] [Patent Document 1] Japanese Patent Application Publication No. 2021-141141 [The problem the invention aims to solve] However, in the prior art described in Patent Document 1 above, the thin object adsorbed onto the adsorption surface of the electrostatic chuck is configured as an insulating layer (ceramic sintered body). Therefore, the following problem exists: in a humid (high humidity) environment, although adsorption can be maintained for a short time, the holding force will decrease over time, and it will be unable to maintain the adsorption of the thin object. This invention addresses the aforementioned problems, aiming to maintain the adsorption of thin-film objects for an extended period in a humid environment. [Technical Means for Solving the Problem] To achieve the above objectives, the electrostatic adsorption tool of the present invention is an electrostatic adsorption tool equipped with an electrostatic adsorption force generating member. This member embeds an electrode group within an electrically insulating layer, and electrostatically adsorbs a thin object by applying a voltage to the electrode group. The electrostatic adsorption force generating member has a water-repellent layer of water-repellent material on at least the adsorption surface of the thin object. [Effects of the Invention] Because of the above-mentioned problem-solving methods, the adsorption of thin objects can be maintained for a long time in a humid environment. Hereinafter, based on Embodiments 1 and 2 shown in the figures, the form of the electrostatic adsorption tool and the object surface processing method for implementing the present invention will be described. [Embodiment 1] In Example 1, the electrostatic adsorption tool uses a wafer, which is the material used to make an IC (Integrated Circuit) chip (semiconductor integrated circuit), as the thin object. The surface processing method for the object is applied to a semiconductor manufacturing apparatus. This apparatus uses various surface processing techniques to fabricate micro-wiring, components, and other circuit patterns on the surface of the object in the adsorption state, thereby manufacturing semiconductor wafer units (dies). The following describes the "structure of the electrostatic adsorption tool A1" and the "surface processing method for the object". [Composition of electrostatic adsorption tool A1 (Figs. 1 to 4)] As shown in Figs. 1 to 3, the electrostatic adsorption tool A1 includes a thin object 10, an electrostatic adsorption force generating member 30, and an adsorption force control unit 40. The term "thin object" refers to a circular thin plate-shaped object with a thickness of 0.5 mm or less, and is representative of an object comprising a circular thin plate formed by the crystallization of semiconductor material, known as a "wafer". Here, "wafer" includes not only the most general silicon wafer, but also silicon carbide wafers, sapphire wafers, and compound semiconductor wafers (gallium phosphide wafers, gallium arsenide wafers, indium phosphide wafers, gallium nitride wafers, etc.). Furthermore, "wafer" also includes glass wafers used as supporting substrates. The electrostatic adsorption force generating component 30 uses an electrostatic electric field to generate adsorption force, thereby performing the function of adsorbing and holding the thin object 10. As shown in Figure 3, the electrostatic adsorption force generating component 30 is configured to include an electrically insulating layer 301, electrode components 302 and 303, a substrate 304, and a first water-repellent insulating layer 305 (water-repellent layer). The electrical insulating layer 301 is an electrical insulating layer disposed on the substrate 304, and electrode elements 302 and 303, which are arranged alternately with positive and negative electrodes, are embedded inside it. The first water-repellent insulating layer 305 uses fluorine material as the water-repellent material and is disposed on the object adsorption side of the electrically insulating layer 301. The first water-repellent insulating layer 305 has an adsorption surface 305a for electrostatically adsorbing the thin object 10. Therefore, the adsorption surface 305a for adsorbing the thin object 10 becomes the surface of the water-repellent layer containing the water-repellent material. Here, "water-repellent" refers to the property of repelling water on the surface. As shown in Figure 3, the adsorption force control unit 40 can be connected to / disconnected from the electrode groups 302 and 303 of the electrostatic adsorption force generating member 30. The adsorption force control unit 40 is connected to the electrode groups 302 and 303 to control the generation / disappearance of electrostatic adsorption force. Furthermore, when electrostatic adsorption force is generated, even when disconnected from the electrode groups 302 and 303, the generation of electrostatic adsorption force is maintained by the charge stored in the electrostatic adsorption force generating member 30. That is, the adsorption force control unit 40 is not a wire that is always connected to the electrode groups 302 and 303 via a wire, but rather a wireless type that disconnects from the electrostatic adsorption force generating member 30 when a charge is stored in it. Here, in the case of no power cord, when adsorbing the thin object 10, the adsorption force control unit 40 is connected to the electrostatic adsorption force generating member 30, and the thin object 10 is electrostatically adsorbed by applying voltage to the electrode group 302, 303, which includes a positive electrode 302 and a negative electrode 303. Moreover, the usage method is configured such that after confirming the generation of electrostatic adsorption force, the adsorption force control unit 40 is disconnected from the electrostatic adsorption force generating member 30, and the generation of electrostatic adsorption force is maintained by the charge stored in the electrostatic adsorption force generating member 30. As shown in Figure 3, the adsorption force control unit 40 includes: a first switch SW1, which controls the conduction between the positive electrode 302 and ground; a second switch SW2, which controls the voltage applied to the positive electrode 302; a third switch SW3, which controls the voltage applied by the second switch SW2; a fourth switch SW4, which controls the conduction between the negative electrode 303 and ground; a fifth switch SW5, which controls the voltage applied to the negative electrode 303; and a sixth switch SW6, which controls the voltage applied by the fifth switch SW5. In the initial state, all switches SW1, SW2, SW3, SW4, SW5, and SW6 of the adsorption force control unit 40 are disconnected. When generating electrostatic adsorption force, the adsorption force control unit 40 is connected to the electrostatic adsorption force generating member 30. After generating electrostatic adsorption force by controlling the on / off state of each switch, the adsorption force control unit 40 is disconnected from the electrostatic adsorption force generating member 30. Moreover, the generation of electrostatic adsorption force is maintained for a long time after disconnection. Therefore, when releasing the electrostatic adsorption force, the adsorption force control unit 40 is connected to the electrostatic adsorption force generating member 30 again, and the electrostatic adsorption force is released by controlling the on / off state of each switch. Next, the principle of generating electrostatic adsorption force using the electrostatic adsorption force generating component 30 will be explained based on Figure 4. The electrostatic adsorption force generating component 30 used in Example 1 is an example of an "electrostatic chuck" that electrostatically adsorbs an object using Coulomb force. The principle of generating electrostatic adsorption force of this "electrostatic chuck" is shown in Figure 4. When a voltage is applied to the electrode, surface polarization is induced on the surface of the object. Here, negative surface polarization is induced on the surface of the object opposite to the electrode portion to which a positive voltage is applied. Also, positive surface polarization is induced on the surface of the object opposite to the electrode portion to which a negative voltage is applied. Moreover, an electrostatic field is formed between the electrode surface and the object surface, resulting from an arc-shaped flow from the positive electrode through the object surface to the negative electrode. This electrostatic field generates an electrostatic adsorption force that adsorbs the object onto the surface of the insulating layer. Furthermore, when releasing the electrostatic attraction, as shown in Figure 4, when the applied voltage to the electrode is cut off, the object returns to its original state (the state where the electrostatic chuck is separated from the object), and no charge is supplied to the object. Moreover, the reason for cutting off the applied voltage to the electrode and not supplying charge to the object is that the electrostatic attraction is induced by the surface polarization of the object through the application of voltage; therefore, if the applied voltage to the electrode is cut off, the surface polarization of the object also disappears. [Surface Processing Method for Objects (Fig. 5)] As described above, the electrostatic adsorption force generating member 30 is configured in a cordless manner, with the adsorption force control unit 40 disconnected from the electrostatic adsorption force generating member 30. Therefore, the electrostatic adsorption tool A1 can adsorb the thin object 10 in a unit state that allows for independent transfer and is then placed into a surface processing apparatus that includes processes in a humid (high humidity) environment. The object surface processing method is performed by placing the object into this surface processing apparatus. Hereinafter, based on FIG. 5, an example of surface processing using the thin object holding unit U, namely, an etching example using the rotary etching apparatus 50, will be described. A method for processing the surface of an object, which uses a thin object holding unit U that electrostatically adsorbs a thin object 10 onto an electrostatic adsorption force generating member 30, includes a transfer step into a rotary etching apparatus 50, a rotary etching processing step, and a transfer step from the outside of the rotary etching apparatus 50. The internal transfer step involves transferring and placing the thin object holding unit U inside a rotary etching apparatus 50 (an example of a surface processing apparatus including processes in a humid environment) that generates circuits through etching. Here, the rotary etching apparatus 50 refers to an apparatus used in semiconductor manufacturing to etch and peel off excess thin film exposed during pre-processing, excluding the desired circuitry, using a dropped solvent. As shown in FIG. 5, the rotary etching apparatus 50 includes, for example, a unit support stage 51, a support stage shaft 52, a motor 53, a cleaning water support container 54, and a cleaning water spray nozzle 55, and the thin object holding unit U is placed on the unit support stage 51. The rotary etching process is a circuit generation process that uses etching to create the desired circuit on a thin-film object holding unit U. This circuit generation process includes a photomask fabrication process, a pre-etching cleaning process, a resist coating process, an exposure process, a resist removal process, an etching process, a hardened resist removal process, and a post-etching cleaning process. Furthermore, the pre-etching cleaning process and the post-etching cleaning process are processes performed in a humid environment using a cleaning solution. Moreover, in addition to these cleaning processes, processes performed using various liquids other than the cleaning solution, such as the resist coating process, the resist removal process, and the etching process, are also included in the humid environment processes. The external transfer step is performed when the rotary etching process is completed. The thin object holding unit U is removed from the internal processing position of the rotary etching apparatus 50 while maintaining the processed thin object 10, and then transferred to the outside of the rotary etching apparatus 50. Here, after being transferred to the outside of the rotary etching apparatus 50, when the thin object 10, after film deposition, is separated from the electrostatic adsorption force generating member 30 and removed from the thin object holding unit U, the adsorption force control unit 40 is connected to the external transfer destination to release the electrostatic adsorption force. On the other hand, when film deposition is part of a continuous surface processing process, the thin object 10 is transferred to the next surface processing device provided outside the rotary etching apparatus 50 while still in the state of the thin object holding unit U. Furthermore, when the next surface processing device is the opposite side of the film deposition surface, the electrostatic adsorption force is released, and the thin object 10 is reversed, and electrostatic adsorption force is generated again to electrostatically adsorb the thin object 10, performing film deposition on the back side of the thin object 10. Thus, the object surface processing method refers to performing surface processing on the thin object 10, which maintains an electrostatic adsorption state even in a humid environment, by using a thin object holding unit U composed of a thin object 10 and an electrostatic adsorption force generating member 30. Therefore, the surface processing apparatus that includes processes in a humid environment is not limited to the rotary etching apparatus 50 that generates circuits through etching, but also includes wet etching apparatus, rotary cleaning apparatus, printing and coating apparatus, etc., that include wet (high humidity) processes in the manufacturing process of semiconductor devices. Wet etching equipment uses the corrosive action of chemicals without rotation to peel off excess film outside the desired circuitry, and includes cleaning steps before and after etching. Rotary cleaning equipment uses a cleaning solution while rotating to remove particles (small contaminants invisible to the naked eye), oil, and other pollutants. Printing and coating equipment uses screen printing to produce insulating films, metal films, protective films, etc., and includes cleaning steps before and after printing. Furthermore, its application to either equipment can improve processing performance. Next, the "Background Technology and Problem Solutions" will be explained. [Background Technology and Problem Solutions (Figures 6 and 7)] In recent years, objects requiring precision manufacturing have become increasingly thinner, making these thinner objects, which suffer from reduced strength, difficult to handle. To process these thinner objects without damage during precision manufacturing processes, reinforcement tools such as adsorption holding tools are essential. Furthermore, for thinner objects with significant warping due to thinning, adsorption holding tools are needed to correct the warping. Precision manufacturing processes also involve special environments such as humidity, high temperature, and vacuum, which significantly limits the types of adsorption holding tools that can be used. To advance processing in precision manufacturing processes, it is necessary to maintain adsorption for extended periods (e.g., two weeks) while the thinner object is reinforced using adsorption holding tools. In electrostatic adsorption tools, thin objects can be adsorbed and maintained for a long time in atmospheric or vacuum environments. However, although adsorption can be maintained for a short time in humid (high humidity) environments, the holding force decreases and adsorption cannot be maintained over a longer period of time. For example, in the prior art described in Patent Document 1 above, as shown in FIG6, the thin object is adsorbed onto the adsorption surface of the electrostatic chuck as an insulating layer (ceramic sintered body). Therefore, in a humid (high humidity) environment, although adsorption can be maintained for a short time, the holding force decreases as the time increases, and as shown in FIG6, the thin object peels off from the adsorption surface. In response, the inventors verified the reason for the decrease in holding power in humid (high humidity) environments. As a result, experiments revealed that the electrostatic adsorption tool cannot maintain a normal electric field due to moisture absorption, thus gradually reducing the adsorption force. Furthermore, it was confirmed that by using a water-repellent material in the electrostatic adsorption tool to suppress moisture absorption, thin objects can be adsorbed and held for a longer period. Additionally, for those using fluorine materials as water-repellent materials, it was also confirmed that contamination is reduced through anti-fouling properties. Therefore, based on the above knowledge and understanding, as shown in Figure 7, the electrostatic adsorption force generating component 30 is constructed by setting a first water-repellent insulating layer 305 on the object adsorption side of the electrically insulating layer 301. Therefore, even in a humid (high humidity) environment, moisture absorption is suppressed by the first water-repellent insulating layer 305, as shown in Figure 7. Even for a long time, the holding force F can be maintained, and the thin object 10 can be continuously adsorbed for a long time. As a result, in processes such as spin etching, spin cleaning, and coating, which are processes in a wet (high humidity) environment, it can continuously adsorb and maintain the thin object for a long time, thereby improving the processing capability of each wet (high humidity) process. As described above, the electrostatic adsorption tool A1 and the object surface processing method of Example 1 exhibit the effects listed below. (1) An electrostatic adsorption tool A1 includes an electrostatic adsorption force generating member 30, which embeds electrode elements 302 and 303 within an electrically insulating layer 301. The member applies a voltage to the electrode elements 302 and 303 to electrostatically adsorb a thin object 10. The member 30 has a water-repellent layer (first water-repellent insulating layer 305) of water-repellent material at least on the adsorption surface of the adsorbed thin object 10. Therefore, the adsorption of the thin object 10 can be maintained continuously for a long time in a humid environment. (2) The electrostatic adsorption force generating component 30 has a base plate 304 and an electrically insulating layer 301 in which electrode components 302 and 303 are embedded. The water-repellent layer is a first water-repellent insulating layer 305 set on the object adsorption side of the electrically insulating layer 301. Therefore, by adding a structure based on an existing electrostatic adsorption tool, an electrostatic adsorption tool A1 with water-repellent function in a wet environment by means of the first water-repellent insulating layer 305 can be easily manufactured. (3) The water-repellent layer (first water-repellent insulating layer 305) uses fluorine material as the water-repellent material. Therefore, the anti-fouling effect of the fluorine material can reduce the contamination of the adsorbed thin film object 10. In addition, the anti-fouling effect can improve the cleanliness of the electrostatic adsorption tool A1. Furthermore, the anti-fouling effect can easily remove the film formed on the electrostatic adsorption tool A1 during the film formation process. (4) The thin object object 10 is a thin plate-shaped object with a thickness of 0.5 mm or less. Therefore, as objects requiring precision processes become thinner and thinner, wafers such as silicon wafers that are neatly and tightly held together by electrostatic adsorption using Coulomb force can be included in the thin object object 10. (5) An adsorption force control unit 40 is provided that can be connected to / disconnected from the electrode group 302, 303 of the electrostatic adsorption force generating member 30. The adsorption force control unit 40 is configured to be power-wire-free, that is, it is connected to the electrostatic adsorption force generating member 30 when adsorbing the thin object 10, and disconnected from the electrostatic adsorption force generating member 30 after adsorbing the thin object 10. Therefore, a thin object holding unit U consisting of the thin object 10 and the electrostatic adsorption force generating member 30 in the state of electrostatic adsorption of the thin object 10 can be easily transferred and installed to the surface processing device. (6) The thin object holding unit U, which is composed of an electrostatic adsorption force generating member 30, is transferred to a surface processing apparatus (such as a rotary etching apparatus 50) for processes involving a humid environment. Surface processing is performed by placing the thin object holding unit U inside the surface processing apparatus (such as a rotary etching apparatus 50) at a processing position. When the surface processing is completed, the thin object holding unit U is transferred from the surface processing apparatus (such as a rotary etching apparatus 50) to the outside of the apparatus while holding the surface-processed thin object 10. Therefore, a separate thin object holding unit U, composed of the thin object 10 and the electrostatic adsorption force generating member 30, can be used to perform surface processing in a surface processing apparatus (such as a rotary etching apparatus 50) for processes involving a humid environment while continuously maintaining the adsorption of the thin object 10. In addition, by applying it to a surface processing apparatus (such as a rotary etching apparatus 50) for processes involving a humid environment, the processing performance can be improved. [Example 2] Example 2 is an example of an electrostatic adsorption tool A2 having an electrostatic adsorption force generating component with the entire electrically insulating layer as a water-repellent layer. As shown in Figure 8, the electrostatic adsorption force generating component of Embodiment 2 is configured as follows: it includes electrode components 302 and 303 (positive electrode 302 and negative electrode 303), a base plate 304, and a second water-repellent insulating layer 306 (water-repellent layer). The second water-repellent insulating layer 306 is a layer that serves as both an electrical insulating layer and a water-repellent layer, in which electrode elements 302 and 303, which are disposed on the substrate 304 and alternately arranged with positive electrodes 302 and negative electrodes 303, are embedded. That is, the second water-repellent insulating layer 306 is a layer that is set by replacing the entire electrical insulating layer. Moreover, the second water-repellent insulating layer 306 is the same as the first water-repellent insulating layer 305 in Embodiment 1, using fluorine material as the water-repellent material, and has an adsorption surface 306a for electrostatically adsorbing the thin object 10. Therefore, the adsorption surface 306a for adsorbing the thin object 10 becomes a water-repellent layer containing water-repellent material. Furthermore, since the other components and object surface processing methods in Example 2 are the same as those in Example 1, illustrations and descriptions are omitted. As described above, in the electrostatic adsorption tool A2 and the object surface processing method of Example 2, in addition to the effects of (1), (3), (4), (5), and (6) of Example 1, the following effects are also achieved. (7) The electrostatic adsorption force generating component 30 has a base plate 304 and an electrically insulating layer in which electrode components 302 and 303 are embedded. The water-repellent layer is a second water-repellent insulating layer 306 that replaces the entire electrically insulating layer. Therefore, an electrostatic adsorption tool A2 that has a water-repellent function in a humid environment can be manufactured by omitting the electrically insulating layer and using the second water-repellent insulating layer 306. In addition, by expanding the second water-repellent insulating layer 306 to the area where the electrode components 302 and 303 are embedded, a higher moisture absorption suppression effect than the first water-repellent insulating layer 305 can be obtained. The electrostatic adsorption tool and object surface processing method of the present invention have been described above based on Embodiments 1 and 2. However, the specific configuration is not limited to these embodiments, and changes in design and additions to the configuration are permitted as long as they do not depart from the inventive spirit of each claim in the patent application. In Examples 1 and 2, examples were shown where a wafer, a material used to make an IC chip (integrated semiconductor circuit), was used as the thin object 10. However, the thin object is not limited to a wafer. For example, in a processing apparatus utilizing a humid environment, a film that addresses the problem of reduced holding force of electrostatic adsorption tools may also be used. In Example 1, a first water-repellent insulating layer 305 is shown as a water-repellent layer disposed on the object adsorption side of the electrically insulating layer 301. In Example 2, a second water-repellent insulating layer 306 is shown as a water-repellent layer disposed in place of the entire electrically insulating layer. However, the water-repellent layer is not limited to the structure shown in Examples 1 and 2. In short, as long as the water-repellent layer has a water-repellent material on the adsorption surface of the object adsorbing the thin material, it can be, for example, a structure in which a water-repellent resin film or the like covers the entirety or a portion of the electrostatic adsorption force generating member. Examples 1 and 2 illustrate preferred examples of using fluorinated materials as the water-repellent material for the water-repellent layers (first water-repellent insulating layer 305 and second water-repellent insulating layer 306). However, the water-repellent material for the water-repellent layer is not limited to fluorinated materials; any material other than fluorinated materials may be used as long as it possesses at least water-repellent properties. [Cross-reference to related applications] This application claims priority based on Japanese Patent Application No. 2022-1771 filed with the Japan Patent Office on January 7, 2022, all disclosures of which are incorporated herein by reference. 10: Thin object; 30: Electrostatic adsorption force generating component; 40: Adsorption force control unit; 50: Rotary etching device; 51: Unit support platform; 52: Support platform shaft; 53: Motor; 54: Cleaning water support container; 55: Cleaning water spray nozzle; 301: Electrical insulation layer; 302, 303: Electrode component group; 304: Base plate; 305: First water-repellent insulation layer; 305a: Adsorption surface; 306: Second water-repellent insulation layer; 306a: Adsorption surface; A1: Electrostatic adsorption tool; A2: Electrostatic adsorption tool; F: Holding force; U: Thin object holding unit. Figure 1 is a top view of the electrostatic adsorption tool A1 of Example 1. Figure 2 is a longitudinal sectional view of the electrostatic adsorption tool A1 of Example 1. Figure 3 is a detailed view of the enlarged structure and adsorption force control unit of the electrostatic adsorption tool A1 of Example 1. Figure 4 is an explanatory diagram of the principle of electrostatic adsorption force generated by the electrostatic chuck. Figure 5 is an explanatory diagram of the surface processing method of the object surface using an example of the surface processing of the thin object holding unit U of Example 1, namely, a rotary etching process. Figure 6 is an explanatory diagram of the adsorption effect of the thin object when there is a moisture absorption effect in the previous example. Figure 7 is an explanatory diagram of the adsorption effect of the thin object when the moisture absorption effect is eliminated in Example 1. Figure 8 is a detailed view of the enlarged structure and adsorption force control unit of the electrostatic adsorption tool A2 of Example 2. 30: Components that generate electrostatic adsorption force 40: Adsorption Force Control Unit 301: Electrical insulation layer 302, 303: Electrode Components Group 304: Base Plate 305: First Water-Repellent Insulation Layer 305a: Adsorption surface A1: Electrostatic Adsorption Tools

Claims

1. An electrostatic adsorption tool, characterized in that: it comprises an electrostatic adsorption force generating member, wherein the electrostatic adsorption force generating member has an electrode group embedded inside an electrically insulating layer, and electrostatically adsorbs a thin object by applying a voltage to the electrode group; the electrostatic adsorption force generating member has at least a water-repellent layer of a water-repellent material on the adsorption surface of the thin object; an adsorption force control part is provided that can be connected / disconnected from the electrode group of the electrostatic adsorption force generating member; the adsorption force control part is configured in a cordless manner, that is, it is connected to the electrostatic adsorption force generating member when adsorbing the thin object, and disconnected from the electrostatic adsorption force generating member after adsorbing the thin object, and the generation of electrostatic adsorption force is maintained by the charge stored in the electrostatic adsorption force generating member; the electrostatic adsorption tool is, when inserted into a surface processing apparatus including a process in a humid environment, wherein the adsorption force control part is disconnected from the electrostatic adsorption force generating member, and it becomes a unit state capable of independently transferring the thin object adsorbed. The electrostatic adsorption force generating component has a base plate and an electrical insulating layer in which the electrode components are embedded. The water-repellent layer is a first water-repellent insulating layer disposed on the object adsorption side of the electrical insulating layer.

2. The electrostatic adsorption tool as claimed in claim 1, wherein the aforementioned water-repellent layer uses fluorine material as the water-repellent material.

3. The electrostatic adsorption tool as claimed in claim 1 or 2, wherein the aforementioned thin object is a thin plate-shaped object with a thickness of 0.5 mm or less.

4. An electrostatic adsorption tool, characterized in that: it comprises an electrostatic adsorption force generating member, wherein the electrostatic adsorption force generating member has an electrode group embedded inside an electrically insulating layer, and electrostatically adsorbs a thin object by applying a voltage to the electrode group; the electrostatic adsorption force generating member has at least a water-repellent layer of water-repellent material on the adsorption surface of the thin object; an adsorption force control part is provided that can be connected / disconnected from the electrode group of the electrostatic adsorption force generating member; the adsorption force control part is configured in a cordless manner, that is, it is connected to the electrostatic adsorption force generating member when adsorbing the thin object, and disconnected from the electrostatic adsorption force generating member after adsorbing the thin object, and the generation of electrostatic adsorption force is maintained by the charge stored in the electrostatic adsorption force generating member; the electrostatic adsorption tool is, when inserted into a surface processing apparatus including a process in a humid environment, wherein the adsorption force control part is disconnected from the electrostatic adsorption force generating member, and it becomes a unit state capable of independently transferring the thin object adsorbed. The electrostatic adsorption force generating component has a base plate and an electrical insulating layer in which the electrode components are embedded. The water-repellent layer is a second water-repellent insulating layer that replaces the entire electrical insulating layer.

5. A method for surface processing of an object, characterized in that: it uses an electrostatic adsorption tool as described in any one of claims 1 to 4, and a thin object holding unit, which is composed of an electrostatic adsorption force generating member for electrostatic adsorption of the thin object, is transferred to a surface processing apparatus that includes a process in a humid environment; the thin object holding unit is disposed at a processing position inside the surface processing apparatus to perform surface processing; when the surface processing is completed, the thin object holding unit is transferred from the surface processing apparatus to the outside of the apparatus while maintaining the surface-processed thin object.

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