Electrostatic chuck and method for manufacturing same

Abstract

Provided are: an electrostatic chuck which has excellent durability and excellent suction force while having a dielectric layer that is formed of a resin; and a method for manufacturing the electrostatic chuck.　Specifically provided is an electrostatic chuck which has an electrode layer 2 between a dielectric layer 1 and an insulating layer 3, wherein: at least the dielectric layer is formed of a dielectric layer resin material that contains a thermoplastic resin; the electrode layer is formed of an electrode layer resin material that contains a thermoplastic resin and a conductive filler; the dielectric layer and the electrode layer are directly joined to each other without using an adhesive; and the dielectric layer 1 has a thickness of 300 µm or more and a volume resistivity at room temperature of not less than 1 × 109 Ω∙cm but less than 1 × 1013 Ω∙cm. The electrostatic chuck is achieved by sequentially depositing and solidifying, by a fused deposition method of a 3D printer, an insulating layer resin material that contains a thermoplastic resin and forms an insulating layer, an electrode layer resin material that contains a thermoplastic resin and a conductive filler and forms an electrode layer, and a dielectric layer resin material that contains a thermoplastic resin and forms a dielectric layer.

Description

Electrostatic chuck and manufacturing method thereof

[0001] The present invention relates to an electrostatic chuck having an electrode layer between a dielectric layer and an insulating layer, and a manufacturing method thereof. More particularly, the present invention relates to an electrostatic chuck that can exhibit excellent chucking force while providing durability by making a resin dielectric layer relatively thick, and a manufacturing method thereof.

[0002] Electrostatic chucks are used in semiconductor manufacturing processes as wafer transport and chucking devices. In recent years, electrostatic chucks have also been attracting attention as a transport and chucking method that can replace conventional clamps and vacuums in the manufacturing and transport processes of glass, film, and textile products such as clothing.

[0003] For example, in the manufacturing process of liquid crystal devices, thin glass sheets must be held (fixed) for processing and processing. However, mechanical clamps cannot process the gripped parts, resulting in waste. Furthermore, as various functional films are used to meet the demand for thinner and lighter electronic devices, using clamps or vacuums to cut the films to a certain size or transport them can result in wrinkles and tears. Furthermore, in the case of fabric, air leaks through the gaps between the fibers, making it unsuitable for vacuum transport. The use of electrostatic chucks is considered as a solution to these problems.

[0004] Electrostatic chucks are becoming more widely used in fields other than semiconductor manufacturing. However, in cases where heat resistance and plasma resistance are not particularly required, such as in semiconductor manufacturing, electrostatic chucks with a dielectric layer made of a resin material rather than a ceramic dielectric layer are used for the purpose of reducing costs.

[0005] As one example, an electrostatic chuck has been disclosed in which a synthetic resin material such as polyurethane is used to form an upper sheet (1) and a lower sheet (2) including a dielectric layer, or a carbon material or the like is blended into these synthetic resin materials to provide appropriate electrical resistivity and dielectric constant (see Patent Document 1). In the electrostatic chuck disclosed in Patent Document 1, a conductive metal such as copper or a conductive plastic is attached to the upper sheet (1) by laminating or pressing them together, or a conductive paste is printed on the upper sheet (1), thereby integrating comb-shaped electrodes (3a) and (3b) with the upper sheet (1) to form an electrode sheet (A).

[0006] Also known is an electrostatic chuck in which a conductive material is used as the conductor and an insulating material is used as the insulator, and each is shaped by a 3D printer to provide an insulator between two conductors forming a positive electrode and a negative electrode, forming an integrated module of three layers, and these modules are arranged to form an attraction surface (see Patent Document 2). Patent Document 2 claims that by stacking multiple modules like the above to create an attraction surface with a large area of ​​fine hair structure, flexibility of the electrostatic attraction surface is ensured, making it possible to freely attract and release soft materials that are difficult to handle, such as plastic film, paper, and cloth.

[0007] Furthermore, an electrostatic chuck is known in which an insulating layer is formed from an acrylonitrile-butadiene-styrene copolymer (ABS), an electrode layer is formed from a conductive paste containing a conductive filler and a resin, and a dielectric layer (functional dielectric layer) having a thickness of 0.001 to 0.025 mm is formed from a resin-based coating such as polycarbonate (PC), and the dielectric layer serves as an attraction surface (see Patent Document 3).

[0008] In the above Patent Document 1, the electrical resistivity of the upper sheet (1) and the lower sheet (2) including the dielectric layer is 1×10 １３ ~1 x 10 １６ This can be said to be a Coulomb force type electrostatic chuck that polarizes the workpiece to be attracted by applying a relatively high voltage (approximately ±1.0 to ±3.0 kV) to the electrode layer that constitutes the internal electrode.

[0009] As can be seen from the following formula (1), the smaller the distance d from the electrode to the attracting surface, the stronger the attracting force F. Therefore, the thickness of the dielectric layer is generally about 25 to 50 μm, and if it is thicker than this, problems will occur in terms of attracting force. In the formula, ε represents the dielectric constant of the dielectric layer, S represents the adsorption area, V represents the applied voltage, and d represents the distance from the electrode to the adsorption surface (surface of the dielectric layer).

[0010] On the other hand, in addition to the Coulomb force mentioned above, the electrostatic chuck also uses the Johnsen-Rahbek force as its attraction principle. This is because the volume resistivity of ceramics is 1×10 in the high-temperature environment used in processing semiconductor wafers. ９ ~1 x 10 １２ This is based on the fact that the electrical resistance is about Ω cm, and by using a ceramic material for the dielectric layer to allow a small amount of current to flow, and applying a voltage to the electrode layer to gradually move charge near the outermost surface of the dielectric layer, the dielectric layer becomes a virtual electrode and attracts the workpiece.

[0011] In such a Johnson-Rahbek force electrostatic chuck, a small current flows at the contact point between the dielectric layer and the workpiece, causing a large local voltage drop between the contact points, which generates a large electric field and thereby exerts an adsorption force on the workpiece. Therefore, rather than bonding the dielectric layer to the electrode layer via an adhesive or the like having a different volume resistivity, it is common to form the dielectric layer by directly applying a ceramic sprayed film exhibiting a predetermined volume resistivity to the electrode layer (see, for example, Patent Document 4). This allows a small current to flow effectively on the outermost surface of the dielectric layer.

[0012] Japanese Utility Model Publication No. 64-42194 International Publication No. 2017 / 150574 Chinese Patent Application Publication No. 108551713 Patent No. 7234459

[0013] As described above, in addition to the semiconductor manufacturing field, when electrostatic chucks are used in manufacturing and transport processes using workpieces such as glass, film, cloth, metal foil, metal plate, metal mesh, etc., methods of forming a dielectric layer using a resin material to reduce costs have been considered. However, if these workpieces are in a rough processed state, for example, there is a risk that the attracting surface of the electrostatic chuck may be damaged by sharp edges being pierced, scratched, worn, etc. This can cause problems such as arcing during workpiece attraction, poor attraction, and damage to the workpiece.

[0014] One possible solution to this problem is to immediately increase the thickness of the dielectric layer to improve durability, but as described above, in a Coulomb force-type electrostatic chuck, an increase in the thickness of the dielectric layer (an increase in the distance from the electrode to the attracting surface) results in a decrease in attracting force. On the other hand, in the case of a Johnson-Rahbek force-type electrostatic chuck, even if a resin film having a predetermined volume resistivity and thickness is used, if it is bonded to the electrode layer using an adhesive or an adhesive-coated pressure-sensitive adhesive sheet or bonding sheet, the presence of the adhesive layer forming the interface between these layers prevents a small current from flowing through the outermost surface of the dielectric layer, and thus sufficient attracting force cannot be obtained.

[0015] Therefore, the present inventors conducted extensive research into an electrostatic chuck that is provided with a resin dielectric layer using a resin material and that can exhibit excellent adsorptive force while improving its durability. As a result, they found that all of the above problems can be solved by using a dielectric layer resin material containing a thermoplastic resin and an electrode layer resin material containing a thermoplastic resin and a conductive filler, and directly bonding these together using a 3D printer to obtain an electrostatic chuck that exhibits a Johnson-Rahbek force type adsorptive force, and thus completed the present invention.

[0016] Therefore, an object of the present invention is to provide an electrostatic chuck that has excellent durability and chucking force while including a resin dielectric layer. Another object of the present invention is to provide a method for manufacturing an electrostatic chuck that can obtain the above-mentioned electrostatic chuck.

[0017] That is, the present invention provides an electrostatic chuck having an electrode layer between a dielectric layer and an insulating layer, wherein the dielectric layer is formed of a dielectric layer resin material containing a thermoplastic resin, and the electrode layer is formed of an electrode layer resin material containing a thermoplastic resin and a conductive filler, and the dielectric layer and the electrode layer are directly bonded together without using an adhesive, and the dielectric layer has a thickness of 300 μm or more and a volume resistivity of 1×10 at room temperature. ９ Ω・cm or more 1×10 １３ The electrostatic chuck is characterized by having a resistivity of less than Ω·cm.

[0018] The present invention also provides a method for manufacturing an electrostatic chuck having an electrode layer between a dielectric layer and an insulating layer, in which an insulating layer resin material containing a thermoplastic resin to form an insulating layer, an electrode layer resin material containing a thermoplastic resin and a conductive filler to form an electrode layer, and a dielectric layer resin material containing a thermoplastic resin to form a dielectric layer are sequentially deposited and solidified by a fused deposition modeling method using a 3D printer to form an insulating layer, an electrode layer, and a dielectric layer, and the insulating layer, the electrode layer, and the dielectric layer have a thickness of 300 μm or more and a volume resistivity of 1×10 at room temperature. ９ Ω・cm or more 1×10 １３ A method for manufacturing an electrostatic chuck characterized by obtaining an electrostatic chuck with a dielectric layer of less than Ω·cm.

[0019] The electrostatic chuck of the present invention includes an electrode layer between a dielectric layer and an insulating layer. At least the dielectric layer is formed of a dielectric layer resin material containing a thermoplastic resin, and the electrode layer is formed of an electrode layer resin material containing a thermoplastic resin and a conductive filler, and these dielectric layer and electrode layer are directly bonded together without using an adhesive. Here, "directly bonded together without using an adhesive" means that no adhesive layer made of anything other than the dielectric layer resin material or the electrode layer resin material is present at the interface between the dielectric layer and the electrode layer, for example, by using an adhesive, a pressure-sensitive adhesive sheet, a bonding sheet (adhesive film), or the like.

[0020] In the present invention, the dielectric layer has a thickness of 300 μm or more, preferably 400 μm or more. If the dielectric layer has a thickness of 300 μm or more, even if the sharp edge of the workpiece pierces or scratches the dielectric layer, there is no risk of causing fatal problems in the electrostatic chuck, such as arcing or poor chucking. The thicker the dielectric layer is, the more durable it is. However, as will be seen from the results of the examples described later, as the distance from the electrode to the workpiece increases, the following equation (resistance Ω) is obtained: "resistance Ω = volume resistivity Ω cm × thickness cm ÷ effective electrode area cm" ２ " increases the resistance value calculated by the formula "V = I x R," and the current I decreases according to Ohm's law "V = I x R," weakening the Johnsen-Rahbek force, which may affect the adsorptive force. For this reason, the dielectric layer should be 2000 μm or less, and preferably 1500 μm or less.

[0021] The dielectric layer has a volume resistivity of 1×10 at room temperature. ９ Ω・cm or more 1×10 １３ Less than Ω cm, preferably 1×10 １１ Ω・cm or more 1×10 １２ The volume resistivity of the dielectric layer is Ω cm or less. As described above, when the volume resistivity of the dielectric layer is in this range, the electrostatic chuck of the present invention can exhibit a Johnson-Rahbek force type attracting force. Note that the electrostatic chuck of the present invention is not limited to use at room temperature, and can also be used in a heated or cooled environment within a range in which the resin does not deform, as long as the Johnsen-Rahbek force can be exhibited.

[0022] In the present invention, from the viewpoint of strengthening the bond at the interface between the dielectric layer and the electrode layer, it is preferable that the melting temperature T ｍ１ and the melting temperature T of the electrode layer resin material ｍ２ Absolute value of the difference between |T ｍ１ -T ｍ２ It is preferable that the temperature | is within 20° C. It is more preferable that the thermoplastic resin contained in the dielectric layer resin material and the thermoplastic resin contained in the electrode layer resin material are the same.

[0023] Furthermore, in the present invention, the insulating layer may be formed of an insulating layer resin material containing a thermoplastic resin. That is, similar to the case of the interface between the dielectric layer and the electrode layer, the electrode layer and the insulating layer may be directly bonded without using an adhesive. In this case, from the viewpoint of strengthening the bond at the interface between the electrode layer and the insulating layer, it is preferable to use a material having a melting temperature T ｍ３ and the melting temperature T of the electrode layer resin material ｍ２ Absolute value of the difference between |T ｍ３ -T ｍ２ is preferably within 20° C. More preferably, the thermoplastic resin contained in the insulating layer resin material and the thermoplastic resin contained in the electrode layer resin material are the same, and most preferably, the thermoplastic resins contained in the dielectric layer resin material, the electrode layer resin material, and the insulating layer resin material are all made of the same resin.

[0024] The manufacturing method for the above-described electrostatic chuck is not particularly limited, but the following method can be preferably used.

[0025] That is, an insulating layer resin material containing a thermoplastic resin to form an insulating layer, an electrode layer resin material containing a thermoplastic resin and a conductive filler to form an electrode layer, and a dielectric layer resin material containing a thermoplastic resin to form a dielectric layer are sequentially deposited and solidified by a fused deposition modeling method using a 3D printer, thereby stacking and integrating the insulating layer, electrode layer, and dielectric layer.

[0026] At this time, the thickness of the dielectric layer after solidification is set to 300 μm or more. The dielectric layer has a volume resistivity of 1×10 at room temperature. ９ Ω・cm or more 1×10 １３ It is sufficient that the volume resistivity is less than Ω cm, and the thermoplastic resin contained in the electrode layer resin material may be appropriately selected so that the volume resistivity of the dielectric layer is within the above range, or the volume resistivity may be adjusted by adding a conductive or insulating filler.

[0027] The 3D printer can be any known device that uses fused deposition modeling (FDM) to eject and layer molten resin from a nozzle. To control the surface roughness of the workpiece chucking surface, a build plate with a build surface having a surface roughness Ra of 3.5 μm or less is preferably used. A dielectric layer resin material is then deposited and solidified on the build surface to obtain an electrostatic chuck equipped with a dielectric layer, an electrode layer, and an insulating layer. The surface roughness Ra refers to the roughness Ra specified in ISO 21920, including the following cases:

[0028] The electrostatic chuck of the present invention is not particularly limited in terms of the workpiece to be attracted, but is suitable for manufacturing and transport processes using workpieces such as glass, film, cloth, paper, metal foil, metal plate, metal mesh, etc. For example, it can be used to attract and hold thin glass sheets used in the manufacturing process of liquid crystal devices that constitute the display parts of liquid crystal televisions and electronic devices, various functional films (resin films) and metal foils used in the manufacturing of electronic devices, as well as cloth when manufacturing cloth products such as clothing and carrier bags.

[0029] In conventional electrostatic chucks using a resin dielectric layer that exhibits the Johnsen-Rahbek force, the thickness of the dielectric layer is approximately 50 to 250 μm, and any thickness greater than this results in a significant decrease in the clamping force. However, according to the present invention, even if the dielectric layer is made thicker, the decrease in clamping force is suppressed, and an electrostatic chuck that has sufficient clamping function even with a thickness of 300 μm or more can be obtained. As a result, an electrostatic chuck that can exhibit excellent clamping force while providing durability by making the resin dielectric layer relatively thick, which was not previously possible, can be obtained.

[0030] Furthermore, conventionally, only electrostatic chucks with a thick dielectric layer have been provided with a ceramic dielectric layer, and compared to the material, manufacturing, and processing costs of ceramics, the electrostatic chuck of the present invention, which is made of resin and has a thick dielectric layer, can reduce costs.

[0031] FIG. 1 is an external perspective view illustrating an electrostatic chuck according to the present invention. FIG. 2 is a cross-sectional view illustrating an electrostatic chuck according to the present invention. FIG. 2(a) is a Y1-Y1 cross-sectional view of FIG. 1, FIG. 2(b) is a Y2-Y2 cross-sectional view of FIG. 1, FIG. 2(c-1) is an example of a Y3-Y3 cross-sectional view of FIG. 1, FIG. 2(c-2) is another example of a Y3-Y3 cross-sectional view of FIG. 1, FIG. 2(c-3) is another example of a Y3-Y3 cross-sectional view of FIG. 1, and FIG. 2(d) is a Y4-Y4 cross-sectional view of FIG. 3. FIG. 3 is a set of process diagrams (a) to (d) illustrating a procedure for manufacturing an electrostatic chuck according to the present invention using a 3D printer. FIG. 4 is a diagram illustrating an electrostatic chuck X used in the examples. FIG. 4(a) corresponds to the Y1-Y1 cross-sectional view of FIG. 1, and FIG. 4(b) corresponds to the Y3-Y3 cross-sectional view of FIG. 1. FIG. 5 is a schematic diagram illustrating a test electrostatic chuck device used to evaluate the chucking force. 6 is a graph showing the results of evaluating the chucking force of the electrostatic chucks according to the present invention and the comparative example. Fig. 7 is a schematic diagram for explaining a laminated test piece for examining the influence of differences in the melting temperature of resin materials used in fused deposition modeling using a 3D printer.

[0032] An electrostatic chuck X according to an embodiment of the present invention and a method for manufacturing the same will be described in detail below with reference to the drawings. However, the present invention is not limited to the contents thereof.

[0033] Fig. 1 shows an external perspective view for explaining an electrostatic chuck X of the present invention. Fig. 2(a) is a Y1-Y1 cross-sectional view in Fig. 1, and similarly Fig. 2(b) is a Y2-Y2 cross-sectional view, Fig. 2(c-1) is a first example of a Y3-Y3 cross-sectional view, Fig. 2(c-2) is a second example of a Y3-Y3 cross-sectional view, Fig. 2(c-3) is a third example of a Y3-Y3 cross-sectional view, and Fig. 2(d) is a Y4-Y4 cross-sectional view.

[0034] The electrostatic chuck X includes an electrode layer 2 between a dielectric layer 1 and an insulating layer 3. At least the dielectric layer 1 and the electrode layer 2 are each formed of a resin material, and the dielectric layer 1 and the electrode layer 2 are directly bonded to each other without using an adhesive. Preferably, the dielectric layer 1, the electrode layer 2, and the insulating layer 3 are each formed of a resin material, and the dielectric layer 1 and the electrode layer 2 are directly bonded to each other without using an adhesive, and the insulating layer 3 and the electrode layer 2 are also directly bonded to each other without using an adhesive.

[0035] The dielectric layer 1 has a thickness of 300 μm or more, preferably 300 μm or more and 2000 μm or less, and more preferably 300 μm or more and 1500 μm or less. The volume resistivity at room temperature is 1×10 ９ Ω・cm or more 1×10 １３ Ω cm, preferably less than 1×10 １１ Ω・cm or more 1×10 １２ It is Ω·cm or less.

[0036] The shape of the electrode layer 2 is not particularly limited and can be appropriately determined depending on the type and size of the workpiece to be attracted. For example, in addition to a monopolar electrostatic chuck consisting of a single flat electrode as shown in FIG. 2(c-1), a rectangular electrode as shown in FIG. 2(c-2), two semicircular electrodes arranged side by side, or a bipolar electrostatic chuck with alternating comb-shaped electrodes as shown in FIG. 2(c-3) may be configured. Note that when configuring a bipolar electrostatic chuck with two electrodes arranged side by side as the electrode layer, if the inter-electrode distance is too close, the minute current required for the Johnsen-Rahbek force to be exerted is consumed between the electrodes rather than flowing to the dielectric layer. Therefore, it is preferable that the inter-electrode distance be approximately the same as or greater than the thickness of the dielectric layer. In other words, the inter-electrode distance should be at least 1.0 times the thickness of the dielectric layer.

[0037] Furthermore, although there are no particular limitations on the thickness of the electrode layer 2, making it relatively thin and suppressing variations in thickness makes it easier to ensure the flatness of the dielectric layer that forms the attraction surface. Therefore, in manufacturing using a 3D printer, it is preferable to form the electrode layer by laminating about one to three layers, and in the case of the examples described below, a thickness of 100 μm to 300 μm is desirable.

[0038] Furthermore, the thickness of the insulating layer 3 is preferably equal to or greater than the thickness of the dielectric layer. As with the inter-electrode distance between the electrode layers constituting the bipolar electrostatic chuck, this is to prevent a minute current for generating the Johnsen-Rahbek force from flowing to the insulating layer instead of the dielectric layer. Therefore, if the thickness of the dielectric layer is 300 μm, the thickness of the insulating layer should also be 300 μm or greater.

[0039] To obtain such an electrostatic chuck X, it is preferable to use a fused deposition modeling method using a 3D printer, and the electrostatic chuck X can be manufactured as follows.

[0040] 3A, first, dielectric layer resin material 11, which contains a thermoplastic resin and forms a dielectric layer, is ejected onto the build surface 20a of the build plate 20. At this time, the filament-shaped dielectric layer resin material 11 is extruded from the nozzle 30 while being melted by heat, and the nozzle 30 is displaced from the home position to the end position along the main scanning direction indicated by the arrow P1, so that the melted dielectric layer resin material 11 is ejected to the specified width of the dielectric layer.

[0041] Next, the 3D printer displaces the mounting portion on which the build plate 20 is placed by one pixel (a distance approximately equivalent to the diameter of the filament ejected from the nozzle 30) in the sub-scanning direction perpendicular to the main operation direction, and returns the nozzle 30 to the home position.

[0042] The 3D printer then repeats the above steps until the specified size and thickness of the dielectric layer is achieved. Finally, the molten dielectric layer resin material 11 is cooled to a temperature at which it will not deform even if an electrode layer or an insulating layer is layered on top of it, thereby forming the dielectric layer 1.

[0043] Here, with regard to the build surface 20a of the build plate 20, in order to control the surface roughness of the workpiece suction surface that adsorbs the workpiece, it is preferable that the surface roughness Ra is 3.5 μm or less, and more preferably 0.005 μm or more and 1.0 μm or less.

[0044] Examples of thermoplastic resins that can be used to form the dielectric layer include polyvinyl chloride (PVC), polylactic acid (PLA), acrylonitrile butadiene styrene (ABS), acrylonitrile styrene acrylate polymer (ASA), polycarbonate (PC), polyamide (nylon PA), thermoplastic polyurethane (TPU), polyethylene (PE), glycol-modified polyethylene terephthalate (PETG), and polyacetal (POM). One or more of these can be used. Among these, thermoplastic polyurethane (TPU), polyvinyl chloride (PVC), and polyacetal (POM) are preferred, as they are advantageous for obtaining a dielectric layer with a predetermined volume resistivity. Thermoplastic polyurethane (TPU), polyvinyl chloride (PVC), and polyacetal (POM) are more preferred, and thermoplastic polyurethane (TPU) is even more preferred.

[0045] Furthermore, a conductive or insulating filler may be added to the dielectric layer resin material as needed, for example, to adjust the volume resistivity. Examples of conductive fillers include carbon black, graphite, carbon nanotubes, carbon fibers, DOP (dioctyl phthalate), DOA (dioctyl adipate), DBA (dibutyl adipate), DEA (diethanolamine), and CAE (citric acid ester). Examples of insulating fillers include epoxy resins.

[0046] 3B, an insulating layer resin material 13 containing a thermoplastic resin is ejected to conform to the shape of the electrode layer 2 to be formed later, surrounding the electrode layer 2. As with the dielectric layer resin material, the insulating layer resin material 13 is extruded from the nozzle 30 while being melted by heat, and the nozzle 30 is displaced from the home position to the end position along the main scanning direction indicated by arrow P1, so that the melted insulating layer resin material 13 is ejected at a predetermined position in a specified frame shape. In other words, a first insulating layer resin material 13A is ejected to fill the gaps between the electrode layers 2 to be formed later and the areas around the electrode layers 2.

[0047] Next, the 3D printer displaces the mounting portion on which the build plate 20 is placed by one pixel (a distance approximately equivalent to the diameter of the filament ejected from the nozzle 30) in the sub-scanning direction perpendicular to the main operation direction, and returns the nozzle 30 to the home position.

[0048] The 3D printer repeats the above operation until the specified size and thickness of the first insulating layer resin material 13A is reached. Finally, the molten first insulating layer resin material 13A is cooled to a degree that prevents deformation, thereby forming the insulating layer 3A, which is a part of the insulating layer 3.

[0049] Here, examples of the thermoplastic resin forming the insulating layer resin material include the same as those used in the dielectric layer resin material described above.

[0050] 3(c), electrode layer resin material 12 containing thermoplastic resin and conductive filler is ejected so as to fill the gaps in the frame-shaped insulating layer 3A obtained above (the gaps in the deposited insulating layer resin material 13A). In this case, as in the above case, electrode layer resin material 12 is extruded from nozzle 30 while being melted by heat, and nozzle 30 is displaced from the home position to the end position along the main scanning direction indicated by arrow P1, so that the melted electrode layer resin material 12 is ejected at a predetermined position to a specified width of the electrode layer.

[0051] Next, the 3D printer displaces the mounting portion on which the build plate 20 is placed by one pixel (a distance approximately equivalent to the diameter of the filament ejected from the nozzle 30) in the sub-scanning direction perpendicular to the main operation direction, and returns the nozzle 30 to the home position.

[0052] The 3D printer repeats the above steps until the electrode layer reaches the specified size and thickness. Finally, the molten electrode layer resin material 12 is cooled to a temperature at which it will not deform even if an insulating layer is layered on top of it, thereby forming the electrode layer 2.

[0053] Here, examples of the thermoplastic resin forming the electrode layer resin material include the same as those for the dielectric layer resin material described above. Examples of the conductive filler include conductive metals such as copper and gold, as well as carbon particles and iodine (I ２ ), bromine (Br ２ ), arsenic pentafluoride (AsF ５ Examples of the conductive polymer include polythiophene, polyacetylene, polyaniline, polypyrrole, and the like doped with .

[0054] 3(d), insulating layer resin material 13 containing a thermoplastic resin is sprayed onto the laminated surface of insulating layer 3A (surface of deposited insulating layer resin material 13A) and onto the laminated surface of electrode layer 2 (surface of deposited electrode layer resin material 12). In this case, as in the above, insulating layer resin material 13 is extruded from nozzle 30 while being melted by heat, and nozzle 30 is displaced from the home position to the end position along the main scanning direction indicated by arrow P1, so that melted second insulating layer resin material 13B is sprayed onto these surfaces, including the insulating layer 3A and the upper surfaces of electrode layer 2, at a predetermined position to a specified width of insulating layer 3.

[0055] Next, the 3D printer displaces the mounting portion on which the build plate 20 is placed by one pixel (a distance approximately equivalent to the diameter of the filament ejected from the nozzle 30) in the sub-scanning direction perpendicular to the main operation direction, and returns the nozzle 30 to the home position.

[0056] The 3D printer repeats the above operation until the specified size and thickness of the second insulating layer resin material 13B is reached. Finally, the molten second insulating layer resin material 13B is cooled to a degree that does not cause deformation, thereby forming the remaining insulating layer 3B, which is a part of the insulating layer 3.

[0057] Here, the thermoplastic resin forming the insulating layer resin material is as described above.

[0058] The electrostatic chuck obtained by the present invention may be used in any manner similar to known methods without any particular limitations. For example, it may be attached to a base substrate having a flow path for a cooling medium and used as an electrostatic chuck device, or it may be attached to a robot hand and used as a transport device for transporting a workpiece. The workpiece to be attracted is also not particularly limited, but as mentioned above, it is suitable for attracting and holding workpieces such as glass, film, cloth, paper, metal foil, metal plate, metal mesh, etc.

[0059] (Example 1 of the Invention: Johnson-Rahbek Force Type Electrostatic Chuck Made of Resin of the Invention) An electrostatic chuck in which the dielectric layer and the electrode layer were directly bonded together using a 3D printer (Example 1 of the Invention) and an electrostatic chuck in which the dielectric layer and the electrode layer were bonded together using an adhesive (Comparative Reference Example 1 described below) were prepared, and tests were conducted to examine the effect of changing the thickness of the dielectric layer on the suction force.

[0060] The 3D printer used was a Raise3D E2 (FDM) fused deposition modeling (FDM) printer manufactured by Raise3D. The printer's specifications included a nozzle diameter of 400 μm, a minimum layer pitch of 20 μm, and positioning accuracy of 0.78125 μm in the X and Y directions and 0.078125 μm in the Z direction. The layer pitch for this test was 100 μm. The build plate used had a build surface with a surface roughness Ra of 0.010 μm.

[0061] First, according to the process diagram (Figure 3) using the 3D printer described above, a dielectric layer resin material was ejected from a nozzle onto the build surface of a build plate to form a dielectric layer 1 measuring 50 mm in length (D) × 50 mm in width (D) × 300 μm in thickness (t1) (see Figure 4; the same applies below). The dielectric layer resin material (filament) used here was PolyFlex TPU95 black, a thermoplastic polyurethane (TPU) manufactured by Polymaker. The nozzle temperature at which it was melted and ejected from the nozzle was 225°C. The printing speed in the main scanning direction (P1) was 20 mm / s. The resulting dielectric layer had a volume resistivity of 8.53 × 10 at room temperature. １１ The value was Ω·cm.

[0062] Next, a thermoplastic resin-containing insulating layer resin material 13A was sprayed to surround the electrode layer 2 to be formed later, conforming to the shape of the electrode layer 2. This formed a frame-shaped insulating layer 3A with a thickness (t2) of 100 μm within an area of ​​50 mm length (D) × 50 mm width (D). The insulating layer resin material (filament) used here was the same as that used to form the dielectric layer, namely, PolyFlex TPU95 black manufactured by Polymaker, a thermoplastic polyurethane (TPU). The nozzle temperature at which the material was melted and ejected was 225°C, and the printing speed in the main scanning direction (P1) was 20 mm / s.

[0063] Next, an electrode layer resin material 12 containing a thermoplastic resin and a conductive filler was sprayed to fill the gaps (gaps between the deposited insulating layer resin material 13A) of the frame-shaped insulating layer 3A obtained above, forming an electrode layer 2 consisting of two rectangular electrodes measuring 46 mm in length (d2), 22 mm in width (d3), and 100 μm in thickness (t2) arranged with an inter-electrode distance (d1) of 2 mm. The electrode layer resin material (filament) used here was made of conductive thermoplastic polyurethane (conductive TPU) manufactured by Recreus, under the trade name Conductive Filaflex, and was melted and ejected from the nozzle at a nozzle temperature of 225°C. The printing speed in the main scanning direction (P1) was 20 mm / s. The resulting electrode layer 2 had an electrical resistivity of 3.9 Ω cm at room temperature.

[0064] Next, a thermoplastic resin-containing insulating layer resin material 13B was sprayed onto the laminated surface of the insulating layer 3A (the surface of the deposited insulating layer resin material 13A) and the laminated surface of the electrode layer 2 (the surface of the deposited electrode layer resin material 12) to form an insulating layer 3B measuring 50 mm in length (D) × 50 mm in width (D) × 500 μm in thickness (t3). The dielectric layer resin material (filament) used here was the same as that used to form the dielectric layer, and was manufactured by Polymaker and made of thermoplastic polyurethane (TPU) under the trade name PolyFlex TPU95 black. The nozzle temperature at which it was melted and ejected was 225°C, and the printing speed in the main scanning direction (P1) was 20 mm / s. In this way, the electrostatic chuck X shown in FIG. 4 was obtained, i.e., an electrostatic chuck X in which the dielectric layer 1 and the electrode layer 2 were directly bonded without the use of an adhesive.

[0065] 5, the electrostatic chuck X obtained above was fixed to a stage 30 having a horizontal mounting surface, with the dielectric layer 1 serving as an attracting surface. In addition, to form a bipolar electrode, voltages of +1500 V and −1500 V were applied to the electrode layer 2 from a high-voltage power supply (not shown).

[0066] A silicon wafer w measuring 15 mm in length, 15 mm in width, and 0.7 mm in thickness was attached to the test electrostatic chuck device prepared in this manner. The silicon wafer w was placed on the attracting surface 1a of the electrostatic chuck X so as to straddle the electrode layer 2, which was composed of two electrodes, as shown in Figures 4(b) and 5. A force gauge 31 was connected to the silicon wafer w, and a voltage was applied to the electrode layer 2 to slowly pull up the silicon wafer w attracted to the attracting surface 1a in the vertical direction (the direction of the arrow). The force (pull-up force) at which the silicon wafer w was released from the attracting surface 1a was evaluated as the attracting force.

[0067] The force (pull-up force) when the silicon wafer w was released from the chucking surface 1 a in the above manner was also evaluated as the chucking force for the following cases: a case in which the thickness of the dielectric layer 1 was set to 500 μm but everything else was the same; a case in which the thickness of the dielectric layer 1 was set to 1000 μm but everything else was the same; and a case in which the thickness of the dielectric layer 1 was set to 1500 μm but everything else was the same. The results are shown in Table 1.

[0068]

[0069] (Comparative Reference Example 1: Conventional Resin-Made Johnson-Rahbek Force-Type Electrostatic Chuck) In Comparative Reference Example 1, an electrostatic chuck was obtained using the same 3D printer as used in Inventive Example 1, as follows. First, a thermoplastic polyurethane sheet measuring 50 mm in length (D) × 50 mm in width (D) × 100 μm in thickness (t1) was prepared as a dielectric layer. The volume resistivity of this thermoplastic polyurethane sheet at room temperature was 6.87 × 10 １１ It is Ω·cm.

[0070] Next, the same insulating layer resin material (filament) as used in the electrostatic chuck X according to Example 1 of the present invention was sprayed from a nozzle onto the build surface of the build plate in the same manner as in Example 1 of the present invention, to form a frame-shaped insulating layer 3A having a thickness (t2) of 100 μm within an area of ​​50 mm in length (D) × 50 mm in width (D) so as to surround the electrode layer 2 to be formed later, in accordance with the shape of the electrode layer 2.

[0071] Next, the same electrode layer resin material (filament) as that used in the electrostatic chuck X according to Example 1 of the present invention was ejected from a nozzle in the same manner as in Example 1 of the present invention to form an electrode layer in which two rectangular electrodes each having a length (d2) of 46 mm, a width (d3) of 22 mm, and a thickness (t2) of 100 μm were arranged side by side with an inter-electrode distance (d1) of 2 mm so as to fill the gaps in the frame-shaped insulating layer 3A.

[0072] Next, the same insulating layer resin material (filament) as that used in the electrostatic chuck X according to Example 1 of the present invention was sprayed from a nozzle in the same manner as in Example 1 of the present invention to form an insulating layer 3B having a length (D) of 50 mm, a width (D) of 50 mm, and a thickness (t3) of 500 μm.

[0073] The dielectric layer made of the thermoplastic polyurethane sheet prepared above was attached to the surface of the electrode layer side of the laminate of the electrode layer and the insulating layer obtained above using a 25 μm thick acrylic double-sided adhesive sheet.

[0074] For the obtained electrostatic chuck according to Comparative Reference Example 1, a test electrostatic chuck device was prepared in the same manner as in Inventive Example 1, and the chucking force when a silicon wafer was chucked was evaluated in the same manner. The chucking force was also evaluated when a thermoplastic polyurethane sheet having a thickness of 300 μm and a thermoplastic polyurethane sheet having a thickness of 500 μm (same as above) were used as the dielectric layer. The results are shown in Table 1.

[0075] 6 is a graph summarizing the clamping forces evaluated for the electrostatic chucks according to Inventive Example 1 and Comparative Reference Example 1 obtained as described above. According to this graph, the clamping force of the electrostatic chuck of Comparative Reference Example 1 drops sharply as the thickness of the dielectric layer increases. In contrast, the inventive example maintains a sufficient clamping force even when the thickness of the dielectric layer increases.

[0076] (Comparative Reference Example 2: Coulomb Force Type Electrostatic Chuck) First, a polyimide sheet having a length (D) of 50 mm, a width (D) of 50 mm, and a thickness (t) of 50 μm was prepared as a dielectric layer. The volume resistivity of this polyimide sheet at room temperature was 2.36×10 １５ It is Ω·cm.

[0077] Next, as in Comparative Reference Example 1, a frame-shaped insulating layer 3A having a thickness (t2) of 100 μm was formed within an area of ​​50 mm in length (D) × 50 mm in width (D). In addition, an electrode layer was formed to fill the gaps in this frame-shaped insulating layer 3A, with two rectangular electrodes having a length (d2) of 46 mm, a width (d3) of 22 mm, and a thickness (t2) of 100 μm arranged with an inter-electrode distance (d1) of 2 mm. Furthermore, an insulating layer 3B having a length (D) of 50 mm, a width (D) of 50 mm, and a thickness (t3) of 500 μm was formed on top of these.

[0078] Then, a dielectric layer made of the polyimide sheet prepared previously was bonded to the surface of the electrode layer side of the laminate of the electrode layer and the insulating layer obtained above using a 25 μm-thick acrylic double-sided adhesive sheet, in the same manner as in Comparative Reference Example 1, to obtain an electrostatic chuck according to Comparative Reference Example 2. Furthermore, when a 50 μm-thick polyimide sheet was layered on the surface of the dielectric layer of the electrostatic chuck according to Comparative Reference Example 2 to make the dielectric layer 100 μm thick, and when five more 50 μm-thick polyimide sheets were layered on top of each other to make the dielectric layer 300 μm thick, these were used as electrostatic chucks according to Comparative Reference Example 2, and their chucking forces were evaluated as in Inventive Example 1. The results are shown in Table 1.

[0079] Reference Example 1 An electrostatic chuck similar to the above-described example of the present invention except that the thickness of the dielectric layer 1 was set to 2000 μm, and an electrostatic chuck similar to the above-described example of the present invention except that the thickness of the dielectric layer 1 was set to 5000 μm were further prepared, and test electrostatic chuck devices were prepared for each of these electrostatic chucks, including the electrostatic chuck obtained above in which the thickness of the dielectric layer 1 was set to 1500 μm.

[0080] Voltages of +1500 V and −1500 V were applied to electrode layer 2 of the obtained test electrostatic chuck device from a high-voltage power supply (not shown), and a 50 mm × 50 mm printed paper was adsorbed. Then, with the printed paper still adsorbed on the adsorption surface of the test electrostatic chuck device, the test electrostatic chuck device was turned vertically downward, and a confirmation test was performed in which the case where the paper was adsorbed without falling was evaluated as "good", and the case where the paper fell was evaluated as "poor". The results are shown in Table 2.

[0081]

[0082] (Reference Example 2) To investigate the effect of differences in the melting temperature of resin materials in fused deposition modeling using a 3D printer, a test was conducted to prepare a laminated test specimen as shown in FIG. 7 . Specifically, in this test, using the 3D printer used in the present invention, a lower member 40 measuring 80 mm long x 32 mm wide x 0.3 mm thick and an upper member 50 measuring 80 mm long x 16 mm wide x 0.3 mm thick were sequentially laminated on the build surface of a build plate. The resin material (filament) forming the lower member 40 and the resin material (filament) forming the upper member 50 were combined to prepare a laminated test specimen, and the resulting laminated test specimen was evaluated. Specifically, a "x" was given when deformation or curvature was observed in the laminated test specimen, the adhesive strength between the lower member 40 and the upper member 50 was weak, or at least partial delamination was observed. Furthermore, a "◎" was given when no deformation or curvature was observed in the laminated test specimen, and no areas of delamination or poor adhesion were observed, and the lower member 40 and the upper member 50 were adhered. The results are shown in Tables 3 and 4.

[0083] The resin materials (filaments) used in this test are as follows, and are shown with their abbreviations in Tables 3 and 4. PLA: polylactic acid (Polylite PLA manufactured by Polymaker, melting temperature 200°C) TPU: thermoplastic polyurethane (PolyFlex TPU95 black manufactured by Polymaker, melting temperature 220°C) PETG: glycol-modified polyethylene terephthalate (PolyMax PETG manufactured by Polymaker, melting temperature 235°C) Nylon: carbon fiber-reinforced nylon filament (PolyMid PA6-CF manufactured by Polymaker, melting temperature 280°C)

[0084]

[0085]

[0086] First, as can be seen from the results in Table 3, when the melting temperature of the resin material forming the upper member 50 (PETG, Nylon) was higher than that of the resin material forming the lower member 40 (PLA) by more than 20°C, deformation and curvature were observed in the obtained laminated test specimens. Furthermore, insufficient adhesion and peeling were observed in some parts of the laminated test specimens. On the other hand, as can be seen from the results in Table 4, when the melting temperature of the resin material forming the lower member 40 (PETG, Nylon) was higher than that of the resin material forming the upper member 50 (PLA) by more than 20°C, peeling was observed in multiple parts of the obtained laminated test specimens, and the adhesion was so weak that the upper member 50 and the lower member 40 easily peeled off.

[0087] As described above, according to the present invention, it is possible to suppress a decrease in chucking force even when the thickness of the resin dielectric layer is increased, which was difficult to achieve in the past. Therefore, it is possible to obtain an electrostatic chuck that can exhibit excellent chucking force while making the resin dielectric layer relatively thick and durable, which was not possible in the past.

[0088] Furthermore, while conventional electrostatic chucks with thick dielectric layers have only been equipped with ceramic dielectric layers, the electrostatic chuck of the present invention, which is made of resin but has a thick dielectric layer, can reduce costs compared to the costs of ceramic materials, manufacturing, and processing. This allows electrostatic chucks to be widely used in a variety of fields and situations, not just in conventional semiconductor manufacturing.

[0089] 1: Dielectric layer, 2: Electrode layer, 3: Insulating layer, 11: Dielectric layer resin material, 12: Electrode layer resin material, 13: Insulating layer resin material, 20: Build plate, 30: Nozzle, 31: Force gauge, 40: Lower member, 50: Upper member.

Claims

1. An electrostatic chuck having an electrode layer between a dielectric layer and an insulating layer, wherein the dielectric layer is formed of a dielectric layer resin material containing a thermoplastic resin, and the electrode layer is formed of an electrode layer resin material containing a thermoplastic resin and a conductive filler, and the dielectric layer and the electrode layer are directly bonded together without using an adhesive, and the dielectric layer has a thickness of 300 μm or more and a volume resistivity of 1×10 at room temperature. ９ Ω・cm or more 1×10 １３ Electrostatic chuck characterized by a resistivity of less than Ω cm.

2. The melting temperature T of the dielectric layer resin material ｍ１ and the melting temperature T of the electrode layer resin material ｍ２ 2. The electrostatic chuck of claim 1, wherein the absolute value of the difference between the temperature and the temperature is within 20°C.

3. The electrostatic chuck according to claim 1, wherein the insulating layer is formed from an insulating layer resin material containing a thermoplastic resin, the electrode layer and the insulating layer are directly bonded together without using an adhesive, and the thermoplastic resin contained in the dielectric layer resin material, the electrode layer resin material, and the insulating layer resin material is made of the same resin.

4. A method for manufacturing an electrostatic chuck having an electrode layer between a dielectric layer and an insulating layer, comprising: sequentially depositing and solidifying an insulating layer resin material containing a thermoplastic resin to form an insulating layer; an electrode layer resin material containing a thermoplastic resin and a conductive filler to form an electrode layer; and a dielectric layer resin material containing a thermoplastic resin to form a dielectric layer by a fused deposition modeling method using a 3D printer; and forming an insulating layer, an electrode layer, and a dielectric layer with a thickness of 300 μm or more and a volume resistivity of 1×10 at room temperature. ９ Ω・cm or more 1×10 １３ A method for manufacturing an electrostatic chuck, characterized in that it provides an electrostatic chuck with a dielectric layer of less than ohm-cm.

5. The method for manufacturing an electrostatic chuck according to claim 4, wherein the dielectric layer is formed by depositing and solidifying a dielectric layer resin material on a build surface of a build plate having a surface roughness Ra of 3.5 μm or less.

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