JP2007324260A - Electrostatic chuck member and apparatus thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrostatic chuck member having no unevenness of attraction in the surface thereof, and to provide an electrostatic chuck apparatus using it. <P>SOLUTION: This electrostatic chuck member comprises an insulating layer 1 consisting of an insulating material, a first electrode layer 2 having an electrode pattern provided on one surface of the insulating layer for generating a potential difference via the insulating layer, a second electrode layer provided on the other surface thereof, and insulating thin films 4 and 5 for covering the surfaces of these two electrode layers. The electrode pattern of the first electrode layer consists of a mesh-shaped electrode 21, the second electrode layer has an electrode pattern consisting of a plurality of island-shaped electrodes 31, and the mesh-shaped electrode 21 of the first electrode layer and the island-shaped electrodes 31 of the second electrode layer are so arranged that they do not overlap each other as seen from the direction perpendicular to the electrode layer surface. The electrostatic chuck apparatus is manufactured by sticking this electrostatic chuck member on a base so that the second electrode layer is located on the base side. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electrostatic chuck member and an electrostatic chuck device using the same.

  An electrostatic chuck device is indispensable in an IC manufacturing process because it exhibits an adsorption function in a vacuum and is easy to handle. In particular, since an electrode sheet for an electrostatic chuck device composed of a plastic film and a copper foil can be manufactured at low cost, an electrostatic chuck device using the electrode sheet is widely used.

  The electrostatic chuck device used in the IC manufacturing process is generally a single-pole type. In this electrostatic chuck device, a semiconductor wafer is regarded as an electrode and a voltage is applied via a dielectric. As a result, a high adsorbing power is expressed.

  In recent years, an attempt has been made to use an electrostatic chuck device to fix an insulating material such as plastic or glass. In this case, since it is difficult for the monopolar electrostatic chuck apparatus to exhibit an electrostatic attraction force, a bipolar electrostatic chuck incorporating two or more electrically insulated electrode surfaces is used. Such a bipolar electrostatic chuck has a structure in which two or more electrode surfaces electrically insulated on the same surface are disposed, and a potential difference of several thousand volts is applied between the two electrodes. Thus, the insulating material is electrostatically adsorbed (for example, Patent Documents 1 and 2).

  In this type of bipolar electrostatic chuck, insulation between electrodes may be ensured by filling an organic material such as an adhesive or a pressure-sensitive adhesive (hereinafter referred to as an adhesive). There is a problem that breakdown due to dielectric breakdown occurs in a short period of time due to problems at the time, foreign substances present in the adhesive, foreign substances and bubbles mixed in the process of filling the adhesive and the like.

  In addition, when the electrostatic chuck device is heated and used, the insulation resistance value of an insulating material such as an adhesive is remarkably reduced, the leakage current between the electrodes is increased, or even if there is no abnormality in the initial stage, When metals such as copper and silver are used for the electrode material, the ionized electrode material gradually elutes inside the insulating material such as the adhesive layer due to the effect of the electric field around the electrode, and finally There was a so-called electromigration problem of causing dielectric breakdown.

In order to improve these points, there has been proposed an electrode sheet for an electrostatic chuck device in which a first electrode layer is provided on one surface of an insulating layer and a second electrode layer is provided on the other surface (see Patent Document 3). ). In the electrode sheet specifically disclosed in this patent document, the first electrode layer is a comb-shaped electrode, and the second electrode layer is provided on the entire surface of the insulating layer, and is a so-called solid without an electrode pattern. It consists of electrodes. In the electrode sheet provided with such a comb-shaped electrode, the wiring between the portion close to the power source of the comb-shaped electrode (source portion) and the portion far from the power source (terminal portion) is a thin and long conductive portion. ing. The electrode having such a structure has a problem that non-uniform adsorption occurs due to a potential difference between the source portion and the end portion of the electrode. This problem becomes more prominent as the electrode pattern becomes finer and the total length of adjacent electrodes in a unit area becomes longer. That is, as the wiring between the source portion and the end portion of the electrode becomes “thin” and “long”, the influence of the slight internal resistance of the electrode made of a conductive material such as metal becomes more conspicuous, and the potential difference between the source portion and the end portion tends to occur Become. Therefore, the electrostatic chuck device using such an electrode sheet has a problem that non-uniformity of electric charge occurs in the electrostatic adsorption surface, and the member to be adsorbed (plastic, glass, etc.) cannot be held with a uniform force. In other words, the attracted member is distorted to generate internal stress, or in the worst case, the attracted member is dropped due to partial adsorption failure.
Japanese Patent Laid-Open No. 11-54602 JP 2000-211961 A JP-A-2005-64105

  The present invention has been made for the purpose of solving the above-mentioned problems in the conventionally proposed electrode sheet for electrostatic chucks having a two-layer electrode structure. Accordingly, an object of the present invention is to provide an electrostatic chuck member that does not cause in-plane non-uniformity of adsorption, and an electrostatic chuck device using the same.

  That is, the electrostatic chuck member of the present invention includes an insulating layer made of an insulating material, a first electrode layer having an electrode pattern provided on one surface of the insulating layer for causing a potential difference through the insulating layer, and The second electrode layer provided on the other surface and an insulating thin film covering the surfaces of these two electrode layers, the insulating thin film on the first electrode layer side is an adsorption surface, The electrode pattern of the first electrode layer is a mesh electrode.

  In the electrostatic chuck member of the present invention, the second electrode layer has an electrode pattern composed of a plurality of island-shaped electrodes, and the mesh electrode of the first electrode layer and the plurality of island-shaped electrodes of the second electrode layer The electrodes are preferably arranged so as not to overlap each other when viewed from the direction perpendicular to the electrode layer surface. In that case, the area of the plurality of island-shaped electrodes of the second electrode layer may be the same as or smaller than the area of the portion of the first electrode layer where the mesh electrode is not present (non-patterned portion).

  The electrostatic chuck device of the present invention is characterized in that the above-described electrostatic chuck member is bonded onto a base material so that the second electrode layer is positioned on the base material side. An electrostatic chuck device according to another aspect of the present invention uses an insulating thin film that covers the surface of the second electrode layer of the electrostatic chuck member as a base material made of an insulating material.

  In the electrostatic chuck member of the present invention, since the first electrode layer has an electrode pattern made of a mesh electrode, not only the end portion far from the power source does not exist, but also a thin and long wiring is eliminated. Therefore, when a voltage is applied so that a potential difference is generated between both the first electrode layer and the second electrode layer, the potential in the electrode surface becomes uniform, and the charge distribution in the electrostatic chuck attracting surface is It produces the effect of being uniform. That is, the voltage drop at the end of the electrode is prevented, the in-plane electric field distribution becomes uniform, and the member to be adsorbed (plastic, glass, etc.) can be held with a uniform force. Furthermore, the delay of the electrostatic adsorption response at the electrode end due to the charge transfer being delayed toward the end is prevented. Therefore, it is possible to prevent the internal stress of the member to be attracted from being generated and to prevent the attracting member from dropping due to partial suction failure. In addition, since a highly insulating insulating layer is interposed between the electrodes, even if the mesh electrode is abnormal or foreign matter or bubbles are mixed in, it is not affected.

  In the present invention, the second electrode layer has an electrode pattern composed of a plurality of island-shaped electrodes, and the network electrode of the first electrode layer and the plurality of island-shaped electrodes of the second electrode layer include When the electrodes are arranged so as not to overlap each other when viewed from the direction perpendicular to the electrode layer surface, when a voltage is applied so that a potential difference is generated between the two electrodes, the mesh electrode of the first electrode layer In the shaded area, an electric field is hardly formed, and the electrostatic attracting force to be generated on the attracted member side is strengthened so that the electrostatic attracting force can be effectively expressed.

  Therefore, the electrostatic chuck device manufactured using the electrostatic chuck member of the present invention exhibits a high adsorption force to the insulating material, has high durability against dielectric breakdown, and is used in a high temperature environment. Is also possible. In particular, the utility value is extremely high with respect to an application for adsorbing an adsorbent made of an insulating material such as glass or plastic.

  The present invention will be described below with reference to the drawings. FIG. 1 is a schematic cross-sectional view of an example of the electrostatic chuck member of the present invention. 2 is a diagram for explaining an electrode pattern of the first electrode layer provided on the surface of the insulating layer, and FIG. 3 is an electrode of the second electrode layer provided on the back surface of the insulating layer. It is a figure for demonstrating a pattern. In FIG. 1, a first electrode layer 2 having an electrode pattern made of a mesh electrode 21 shown in FIG. 2 is provided on one surface of an insulating layer 1 made of an insulating material, and a plurality of island shapes shown in FIG. A second electrode layer 3 having an electrode pattern made of electrodes 31 is provided, and the surfaces of these electrode layers are covered with insulating thin films 4 and 5. In the electrostatic chuck member 10, the mesh electrode 21 of the first electrode layer and the plurality of island electrodes 31 of the second electrode layer do not overlap each other when viewed from the direction perpendicular to the electrode layer surface. Has been placed. That is, the island-shaped electrode of the second electrode layer is disposed so as to be positioned below a portion (non-pattern portion) where the mesh electrode of the first pattern electrode layer does not exist. Note that the plurality of island-shaped electrodes of the second electrode layer are electrically connected to each other by the thin line portion 32. Therefore, a potential difference is generated between the first electrode layer 2 and the second electrode layer 3 via the insulating layer 1.

  In the electrostatic chuck member of the present invention, the second electrode layer may be formed of a whole-area conductive portion that covers the entire surface except for the edge portion of the insulating layer.

  FIG. 4 is a schematic cross-sectional view of an example of the electrostatic chuck device of the present invention. In this electrostatic chuck device, the electrostatic chuck member 10 having the structure shown in FIG. 1 is attached on the base material 7 with the adhesive layer 6 so that the second electrode layer 3 is positioned on the base material side. The insulating thin film 4 on the first electrode layer 2 side forms an adsorption surface.

  FIG. 5 is a schematic cross-sectional view of an example of another aspect of the electrostatic chuck device of the present invention. This electrostatic chuck device has a structure in which the surface of the second electrode layer is covered with a base material 71 made of an insulating material instead of the insulating thin film 5 in the electrostatic chuck member 10 having the structure shown in FIG. The insulating thin film 4 existing on the first electrode layer 2 side forms an adsorption surface.

  Next, each layer constituting the electrostatic chuck member and the electrostatic chuck device of the present invention will be described. The insulating thin film, the first electrode layer, the second electrode layer, and the insulating layer constituting the electrostatic chuck member are described below. Lamination is appropriately performed, such as a method of bonding various materials using an adhesive, a method of bonding various materials without using an adhesive, a method of directly forming each layer by vapor deposition, sputtering, plating, thermal spraying, aerosol deposition, etc. However, the method is not limited at all.

  As an insulating material constituting the insulating layer interposed between the first electrode layer and the second electrode layer, ceramic materials such as silicon carbide, silicon nitride, alumina, zirconia, organic polymer materials such as polyimide, The materials such as inorganic polymer materials such as silicone compounds are not limited at all. When a plastic film is used as the insulating material, films of polyimide, polyethylene terephthalate, polyethylene naphthalate, aramid, polyolefin, polyethersulfone, polyetherketone, polytetrafluoroethylene, polyphenylenesulfide, and the like are preferable. In particular, a highly heat-resistant polyimide film can be preferably used because the leakage current does not increase even at high temperatures and the risk of electromigration is extremely small. The insulating layer may be a laminate of two or more of the above materials.

  The thickness of the insulating layer is not limited in any way, but a range of 1 to 300 μm is preferable, and a range of 12.5 to 300 μm is preferable in consideration of easy availability and easy handling. If the thickness of the insulating layer is less than 1 μm, the insulation is insufficient, and dielectric breakdown occurs at a voltage with a potential difference of several thousand volts. On the other hand, when the thickness is larger than 300 μm, the adsorption force is lowered, which is not preferable. The insulating layer may be formed by, for example, dissolving the insulating material in a solvent and directly coating it on the second electrode layer, or may be formed directly on the second electrode layer by other methods. . The insulating layer may be formed by laminating a film made of the insulating material on the second electrode layer. Moreover, in the case of a film, you may laminate | stack two or more.

  A first electrode layer having an electrode pattern is provided on one surface of the insulating layer on the adsorption surface side, and the electrode pattern needs to be made of a mesh electrode. The mesh shape, the electrode width, and the mesh size of the mesh electrode can be set as appropriate. 6 is a plan view of a mesh electrode having a circular mesh, and FIG. 7 is a plan view of a mesh electrode having a hexagonal mesh.

  Moreover, although the 2nd electrode layer may consist of the solid electrode which the whole area | region is an electroconductive part, it is preferable to have an electrode pattern which consists of an island-shaped electrode. The shape and size of the island-shaped electrode may be determined as appropriate, and examples thereof include an arbitrary shape such as a quadrangle as shown in FIG. 3, a circle as shown in FIG. 8, and a hexagon as shown in FIG. The When the second electrode layer has an electrode pattern composed of island-shaped electrodes, the network electrode of the first electrode layer and the island-shaped electrode of the second electrode layer are viewed from the direction perpendicular to the electrode layer surface. It is desirable that they are arranged so as not to overlap. In that case, the area of the island electrode of the second electrode layer may be the same as or smaller than the area of the portion of the first electrode layer where the mesh electrode does not exist. Further, the electrodes of the island-like electrode are electrically connected to each other by appropriate means.

  The first electrode layer and the second electrode layer can be formed by vapor deposition, sticking, coating, etching, or the like using various metal foils, conductive films, conductive pastes, and the like. The material and the thickness are not limited at all, but the film thickness is preferably as long as it is within a range in which conductivity can be secured over a long period of time. A metal foil having a thickness of 150 μm or less, particularly 35 μm or less, for example, Copper foil is preferred. A thickness greater than 150 μm is not preferable because it is difficult to produce a pattern.

  In order to ensure insulation against the object to be adsorbed and the substrate, the first electrode layer and the second electrode layer are each coated with an insulating thin film. Further, in order to prevent discharge, the edges of the first electrode layer and the second electrode layer must be sealed with an insulating thin film so as not to be exposed to the outside. .

  As a suitable material for the insulating thin film, the same insulating material used for the insulation between the first electrode layer and the second electrode layer is used, and various kinds of materials including insulating alumina are used. Inorganic materials, polymer materials such as epoxy resin compositions, and the like can also be mentioned.

  The thickness of the insulating thin film provided on the first electrode layer is set in the range of 1 to 300 μm. If the distance from the object to be adsorbed to the electrode layer is smaller than 1 μm, the mechanical strength is insufficient, so that the durability is not achieved, and if it is larger than 300 μm, the adsorbing power is reduced. Although it is more desirable to set in the range of 25 to 150 μm, in actual use, it may be determined as appropriate depending on the desired function of the electrostatic chuck device and the characteristics of the material used. In addition, the thickness of the insulating thin film provided on the second electrode layer may be set as appropriate as long as the insulating property with the base material can be ensured.

  Note that the insulating thin film can be either a single layer structure or a laminated structure of a plurality of materials. In the case of a laminated structure, a conductive material may be included as long as insulation is ensured.

  The electrostatic chuck device of the present invention is formed by sticking the above-described electrostatic chuck member on a substrate. In that case, the second electrode layer of the electrostatic chuck member is attached so as to be positioned on the base material side, and the insulating thin film covering the first electrode layer forms an adsorption surface. The substrate is not particularly limited, and for example, a metal substrate such as an aluminum substrate can be used. In another electrostatic chuck device of the present invention, an insulating thin film that covers the surface of the second electrode layer in the electrostatic chuck member is used as a base material made of an insulating material. Also in this case, the insulating thin film covering the first electrode layer becomes the adsorption surface. The base material made of an insulating material is not particularly limited, and those made of the insulating material described for the insulating thin film can be used.

  In the present invention, holes are formed in the electrostatic chuck member or the substrate of the electrostatic chuck device for gas injection, temperature adjustment with a refrigerant, lifter pin device, detector installation, etc., as necessary. Attached devices such as a heater for adjusting the temperature may be incorporated.

  The layers constituting the electrostatic chuck member of the present invention may be laminated by an appropriate method as described above, but an adhesive is used for laminating the layers and attaching the electrostatic chuck member and the substrate. As the adhesive, a non-conductive adhesive is preferable. In order to ensure high insulation reliability, an adhesive composed of an epoxy resin, a phenol resin, a diallyl phthalate resin, a thermoplastic polyimide resin, a maleimide resin, or the like is preferable. These resins may be used alone or in combination of two or more. Further, various elastomers such as NBR may be blended in order to impart flexibility, and various inorganic fillers including metal powder and alumina may be dispersed in order to improve thermal conductivity. It is also effective to add a coupling agent in order to improve the adhesive properties. The adhesive may be in the form of liquid or solid. In addition, since it is not necessary to have a high insulating property other than the portion in contact with the electrode layer, there is no limitation in selecting an adhesive or the like, and a conductive adhesive or the like may be used in some cases. Absent.

  In the case of using the above adhesive, it is preferable that the thickness of the formed adhesive layer is thin as long as the interlayer adhesive force can be secured. Specifically, it is 100 μm or less, more preferably 1 to 50 μm.

  There are no restrictions on the method of laminating with adhesive, but in order to ensure ease of handling and thickness accuracy after lamination, a solid adhesive is applied to the peelable film at a predetermined thickness at room temperature. It is desirable to transfer and use a so-called dry film. Moreover, you may use the plastic film with an adhesive agent by which the normal temperature solid adhesive agent was apply | coated to the single side | surface or both surfaces beforehand. Furthermore, for example, a structure in which a copper foil is directly laminated on one or both sides of a polyimide film may be used, and an electrode layer may be provided on the polyimide film without using an adhesive or the like.

  When a voltage is applied so that a potential difference is generated between the first electrode layer and the second electrode layer of the electrostatic chuck device using the electrostatic chuck member of the present invention, the insulating film on the first electrode layer side is covered. The adsorbent is adsorbed. As the voltage application method, any method can be applied as long as a potential difference can be generated between the first electrode layer and the second electrode layer. That is, a method of applying voltages of different polarities between the first electrode layer disposed on the adsorption surface side and the second electrode layer disposed on the substrate side, and grounding the first electrode layer (earth electrode) Any of a method of applying a + or − voltage to the second electrode layer and a method of grounding the second electrode layer and applying a + or − voltage to the first electrode layer may be used. However, it is most preferable to ground the first electrode layer and apply a DC voltage to the second electrode layer. If these methods are adopted, it is possible to prevent the occurrence of dielectric breakdown even when foreign matter is present between the object to be adsorbed and the adsorbing surface during use or wrinkles occur on the adsorbing surface.

  Hereinafter, the present invention will be described with reference to more specific examples, but the present invention is not limited thereto.

(Example 1) (Production of electrostatic chuck device)
12 μm thick copper foil (trade name: manufactured by Mitsui Mining & Smelting Co., Ltd.) on both sides of a polyimide film (trade name: Kapton 200H, 50 μm thickness, manufactured by Toray DuPont) through an adhesive film of 20 μm thickness. TQ-VLP) is laminated. Subsequently, a mesh electrode (shape shown in FIG. 2) having a 0.8 mm wide mesh portion (conductive portion) and a 1.5 mm × 1.5 mm mesh portion (insulating portion) on one copper foil surface by etching. A first electrode layer having a reticulated pattern is formed. Similarly, a second electrode layer having an area of 90 × 90 mm having an electrode pattern made of island-shaped electrodes of 1.5 mm × 1.5 mm (the shape shown in FIG. 3) is formed on the other copper foil surface. To do. In that case, etching is performed so that the island-shaped electrode of the second electrode layer does not overlap with the mesh electrode (conductive portion) of the first electrode layer when viewed from the direction perpendicular to the polyimide film. That is, the island-shaped electrode is formed so that the conductive portion of the first electrode layer is located at the insulating portion of the second electrode layer. In the etching, a thin line portion having a width of 100 μm is formed between the individual electrodes of the island-shaped electrodes so that the island-shaped electrodes are electrically connected to each other. Thereafter, a polyimide film (Kapton 200H) is further laminated on both electrode layers via an adhesive film having a thickness of 20 μm to obtain a sheet-like electrostatic chuck member.

  After this sheet-like electrostatic chuck member is cut to a predetermined size, the second electrode layer side is attached to a 5 × 100 × 100 mm aluminum substrate using an adhesive film having a thickness of 20 μm, and electrostatic Manufacture a chuck device.

  In addition, the adhesive film used for said sticking is as follows. A composition having a weight ratio of 1: 1 between a resole phenol resin (trade name: Shonor CKM-908A, manufactured by Showa Polymer Co., Ltd.) and NBR (trade name: Nipol 1001, manufactured by Nippon Zeon Co., Ltd.) is used as an adhesive. This composition was dissolved in methyl ethyl ketone to prepare an adhesive paint having a solid content of 30% by weight, applied to one side of a releasable polyethylene terephthalate film (thickness 38 μm), and then heated and dried at 150 ° C. for 3 minutes. An adhesive film having a thickness of 20 μm is prepared.

  Moreover, lamination | stacking of the adhesive film on a polyimide film or copper foil, and lamination | stacking of the copper foil or a polyimide film on an adhesive film are all implemented by 150 degreeC continuous lamination.

  The sheet-like electrostatic chuck member and the aluminum base material are bonded together by a vacuum press at 150 ° C./30 minutes, and after the vacuum press operation, in order to complete the thermosetting of the adhesive, it is performed at 150 ° C./12 hours Apply heat treatment.

(Example 2)
An electrostatic chuck device is manufactured by the same material and working conditions as in Example 1 except that the polyimide film used for the suction surface is made of Upilex 75S (manufactured by Ube Industries, Ltd., thickness 75 μm) instead of Kapton 200H.

It is typical sectional drawing of an example of the electrostatic chuck member of this invention. It is a top view of an example of the 1st electrode layer. It is a top view of an example of the 2nd electrode layer. It is typical sectional drawing of an example of the electrostatic chuck apparatus of this invention. It is typical sectional drawing of an example of the other aspect of the electrostatic chuck apparatus of this invention. It is a top view of other examples of the 1st electrode layer. It is a top view of other examples of the 1st electrode layer. It is a top view of other examples of the 2nd electrode layer. It is a top view of other examples of the 2nd electrode layer.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Insulating layer, 2 ... 1st electrode layer, 3 ... 2nd electrode layer, 4 ... Insulating thin film, 5 ... Insulating thin film, 6 ... Adhesive layer, 7 ... Base material, 10 ... Electrostatic chuck member , 21 ... mesh electrode, 31 ... island electrode, 32 ... fine wire portion, 71 ... substrate.

Claims (8)

  An insulating layer made of an insulating material; a first electrode layer having an electrode pattern provided on one surface of the insulating layer for generating a potential difference through the insulating layer; and a second electrode layer provided on the other surface An electrostatic chuck member comprising an insulating thin film covering the surfaces of these two electrode layers, wherein the insulating thin film on the first electrode layer side is an adsorption surface, and the electrode of the first electrode layer An electrostatic chuck member, wherein the pattern is a mesh electrode.   The second electrode layer has an electrode pattern composed of a plurality of island-like electrodes, and the mesh electrode of the first electrode layer and the island-like electrode of the second electrode layer are perpendicular to the electrode layer surface. The electrostatic chuck member according to claim 1, wherein the electrostatic chuck member is disposed so as not to overlap each other when viewed from a direction.   The area of the plurality of island-shaped electrodes of the second electrode layer is the same as or smaller than the area of the portion of the first electrode layer where the mesh electrode is not present. Chuck member.   The electrostatic chuck member according to claim 1, wherein the mesh electrode of the first electrode layer and the electrode of the second electrode layer are made of a metal foil having a thickness of 150 μm or less.   The electrostatic chuck member according to claim 1, wherein the insulating layer made of an insulating material is a polyimide film having a thickness of 1 to 300 μm.   2. The electrostatic chuck member according to claim 1, wherein the insulating thin film covering the surfaces of the first electrode layer and the second electrode layer is made of a polyimide film having a thickness of 1 to 300 [mu] m.   An electrostatic chuck device comprising the electrostatic chuck member according to claim 1 attached to a base material so that the second electrode layer is positioned on the base material side.   An insulating layer made of an insulating material; a first electrode layer having an electrode pattern provided on one surface of the insulating layer for generating a potential difference through the insulating layer; and a second electrode layer provided on the other surface And an insulating thin film covering the surface of the first electrode layer and a base material made of an insulating material covering the surface of the second electrode layer, wherein the insulating thin film is an electrostatic surface. An electrostatic chuck device, wherein the electrode pattern of the first electrode layer is a mesh electrode.

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