JP5055912B2 - Fine molding mold and manufacturing method thereof - Google Patents

Description

  The present invention relates to a fine mold and a method for manufacturing the same.

  Conventionally, as a technique for forming a high-aspect and fine three-dimensional shape at low cost, a fine molding technique such as hot embossing or nanoimprint using a fine molding mold is known. Various technologies have been developed to produce highly functional fine molds that satisfy complex requirements such as high hardness, high thermal conductivity, and high durability by forming a film according to the application.

  Patent Document 1 discloses a method for improving the corrosion resistance of a fine mold by forming a film made of nitride of titanium or chromium on a base made of nickel formed by electroless plating by PVD.

  Patent Document 2 discloses a method of forming a film made of metal, ceramics, or a composite material thereof on a fine mold by thermal spraying.

Patent Document 3 discloses a method of forming a hard film on a fine mold by plasma carburizing or plasma nitriding on the surface of a silicon substrate.
Japanese Patent Laid-Open No. 11-105039 JP-A-2005-47148 JP 2004-148494 A

  In the methods disclosed in Patent Documents 1, 2, and 3, the entire molding surface of the fine mold is covered with a hard film formed by deposition. However, in general, when a film is formed by deposition, the higher the hardness, the higher the accumulated stress during the deposition. Therefore, if the entire molding surface of the fine mold is covered with a hard film, there is a problem that the fine mold is warped. Further, as disclosed in Patent Document 2, when a film is formed by ceramics, chipping is likely to occur because of low toughness.

  The present invention was created to solve this problem, and an object of the present invention is to reduce warpage of a fine mold suitable for hot embossing and nanoimprinting.

(1) A fine mold for achieving the above object is selected from a substrate and W, Ta, Ti, Mo, Cr, TiN, TaN, MoN, NiP, NiW, NiCo, NiFe, NiMn, and NiMo. A hard film made of a compound of a melting point metal or a refractory metal and forming a part of the molding surface and divided, and the hard film bonded to the surface of the substrate and having at least a part of the surface layer having a higher hardness than the surface of the substrate The hard film forming the protrusion is in close contact with the side surface and the bottom surface of the concave portion on the surface of the substrate.

  By forming only a part of the molding surface of the fine molding mold with the divided hard film, the warping of the fine molding mold can be reduced as compared with the case where the entire molding surface is formed with the hard film. Moreover, both high melting point metals and high melting point metal compounds have hardness, toughness, and thermal conductivity suitable for hot embossing and nanoimprinting.

Irregularities of the molding surface of the fine pore mold is composed of a surface of the surface and the projection of the substrate. When a plurality of protrusions are dispersed on the substrate, the fine mold is unlikely to warp depending on the stress of the film having high hardness forming the surface layer of the protrusions. Therefore, by adopting the structure of the fine mold, warping of the fine mold can be reduced.

When the hard film forming the protrusion is in close contact with the side surface and the bottom surface of the concave portion on the surface of the substrate, the protrusion is compared with the case where the protrusion is bonded to the surface of the flat substrate. The bonding area between the film constituting the substrate and the substrate increases. Therefore, the strength of the fine mold is increased by adopting this structure.

  (7) A method for producing a fine mold for achieving the above object is to form an uneven area on the surface of a material substrate for forming the substrate of the fine mold, and deposit the hard film on the uneven area. And removing the hard film until the material substrate is exposed, and removing the surface layer of the material substrate to form the protrusions and the substrate.

  In this manufacturing method, the hard film for forming the protrusion is divided by removing the hard film for forming the protrusion until the material substrate is exposed. Therefore, by adopting this manufacturing method, it is possible to reduce the warpage of the fine mold. By using a lithography technique or the like, an uneven region having a side surface perpendicular to the surface to be molded and having a high aspect can be formed on the material substrate, and the smoothness of the surface constituting the uneven region is increased. In addition to the lithography technique, suitable methods for forming the concavo-convex region include, for example, press processing (nanoimprint or hot embossing) of a resin substrate, direct ion beam drawing, nano-order mechanical processing, electric discharge processing, and the like. Moreover, you may form an uneven | corrugated area | region by machining, such as cutting of a glass substrate and sandblasting. Therefore, according to this manufacturing method, the unevenness | corrugation which has a side surface perpendicular | vertical with respect to a shaping | molding target surface and the smoothness of an element surface can be formed in the shaping | molding surface of a fine mold. By forming a protrusion having a side surface perpendicular to the surface to be molded and having high smoothness on the molding surface of the fine mold, the product to be molded is not easily deformed at the time of mold release.

  Further, in this manufacturing method, when the protrusions and the substrate are formed by removing the surface layer of the material substrate, if the end point is controlled so that the recesses in the uneven region of the material substrate remain, the hard layer constituting the surface layer of the protrusions Since the fine mold is completed with the film in close contact with the bottom and side surfaces of the concave portion of the substrate, the film and the substrate constituting the protrusion are compared with the case where the end point control is performed so that the concave portion of the concave and convex region of the material substrate disappears. And the bonding area increases, and the strength of the fine mold increases.

  Definitions of terms used to specify the above-described invention are as follows. The high melting point metal is W, Ta, Ti, Mo, Cr or the like having a relatively high melting point among metals. The refractory metal compound is a compound of these refractory metal elements and other elements. The molding surface is the surface of the fine molding mold that contacts the molding object. The hard film may be a multilayer film or a single layer film. Further, in the claims, “to the upper” means both “without an intermediate on the top” and “with an intermediate on the upper” unless there is a technical impediment. . Further, the order of the operations described in the claims is not limited to the order of description as long as there is no technical obstruction factor, and may be executed at the same time, may be executed in the reverse order of the description order, or may be continuous. It does not have to be executed in order.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
(First reference form )
Figure 1 is a sectional view showing a first reference embodiment of a method for manufacturing a fine thin mold.

  First, as shown in FIG. 1A, a single crystal Si wafer as a sacrificial substrate is coated with a photoresist, pre-baked and cured, then exposed with a stepper, aligner, electron beam, etc., developed, and post-baked to form a photoresist. A mask 11 is formed. The coating thickness of the photoresist is, for example, 100 μm. The pattern of the photoresist mask 11 is set according to the shape of the molding surface of the fine mold 1 (see FIG. 1E). The scale of the pattern is, for example, a protrusion width of 20 μm and a recess width of 20 μm.

Subsequently, the sacrificial mold 12 having the concavo-convex region 10 is formed by transferring the pattern of the photoresist mask 11 to the wafer by anisotropic etching such as RIE. The etching gas is selected from, for example, CF ₄ , CH ₂ F ₂ , CH ₃ F, and the like. The etching end point is controlled to a depth of 30 μm, for example. Further, the side surface of the concave portion does not have to be a vertical surface as illustrated, and may be, for example, a tapered surface. By forming the concavo-convex region 10 of the sacrificial mold 12 by RIE, the smoothness of the element surface constituting the concavo-convex region 10 is increased.

The material of the sacrificial substrate is not limited to a single crystal Si wafer, but may be any material that can form the concavo-convex region 10 constituted by a sufficiently smooth element surface by etching. For example, SiN _x , SiO ₂ , amorphous Si, polycrystalline Si Etc. may be used.

  Note that the sacrificial mold 12 having the concavo-convex region 10 may be formed by using an ion beam direct drawing method, an imprint method, or a plating method without using the photoresist mask 11. Hereinafter, a method of forming the sacrificial mold 12 using the deposition method and the imprint method will be described.

  In the deposition method, a sacrificial mold 12 can be obtained by forming a metal film that can be easily peeled on the surface of the master mold by plating, vapor deposition, or sputtering, and peeling the metal film from the master mold. Irregularities to be transferred to the sacrificial mold 12 can be formed on the surface of the master mold by nano-order machining or electric discharge machining. Stainless steel is suitable as a material for the master mold from which the metal film can be peeled off. Sn, zinc, bismuth, indium and the like formed on the surface of the master mold made of stainless steel can be peeled off from the master mold using a fluorine-based or fluorine-overwater-based release agent.

In the imprint method, the sacrificial mold 12 to which the concavities and convexities of the master mold are transferred is formed by pressing a master mold made of stainless steel or the like against low-melting glass, low-melting metal, thermosetting resin, photo-curing resin, thermoplastic resin, or the like. be able to.
The method for forming the sacrificial mold 12 has been described above.

  Next, as shown in FIG. 1B, a film 13 made of metal and a base film 14 are deposited on the uneven region 10 of the sacrificial mold 12. The film 13 and the base film 14 are films for forming the protrusions 18 of the fine mold 1 and are formed of a refractory metal or a compound of a refractory metal, and particularly a nitride or oxynitride of a refractory metal. It is desirable to form a hard film. Specifically, for example, as follows.

  First, the coating 13 is formed by depositing TiN which also functions as a seed layer of the base film 14 on the surface of the sacrificial mold 12 by sputtering. The total film thickness of the film 13 and the base film 14 is preferably less than ½ of the recess width (W) so that the recess of the sacrificial mold 12 is not filled with the film alone. 5 μm. Before depositing TiN, an intermediate layer such as Ti may be deposited to a thickness of, for example, 0.1 μm to improve the adhesion. The material of the film 13 may be TaN. The gas used for sputtering may be an inert gas or a reactive gas. The film 13 may be deposited by CVD instead of sputtering.

  After depositing the film 13, a metal is deposited on the surface of the film 13 to form a base film 14 having a thickness of 50 μm, for example. Specifically, W is deposited on the surface of the film 13 by, for example, the CVD method. The material composition of the base film 14 is appropriately determined depending on the function required for the fine mold 1 such as Ta, Ti, Mo, Cu, TiN, TaN, MoN, NiP, NiW, NiCo, NiFe, NiMn, NiMo, Ni, Cr, and the like. Selected. The method for depositing the base film 14 may be electrolytic plating or electroless plating.

  Next, as shown in FIG. 1C, the base film 14 and the film 13 are removed by grinding or polishing until the sacrificial mold 12 is exposed. As a result, the surface of the workpiece composed of the sacrificial mold 12, the base film 14, and the film 13 is flattened, and the film 13 and the base film 14 are both divided.

  Next, as shown in FIG. 1D, a thick metal film 16 (for example, 200 μm) is formed on the surface of the work composed of the sacrificial mold 12, the base film 14, and the film 13 through the seed layer 15. In order not to generate a strong stress on the seed layer 15 and the metal film 16, a material having a hardness lower than that of the base film 14 than that of the film 13 is used as these materials. Further, by using Cu or the like having a relatively high thermal conductivity among metals as the material of the metal film 16, when hot embossing or thermal imprinting is performed using the fine mold 1, the film 13 or Even if the thermal conductivity of the base film 14 is low, temperature spots are less likely to occur on the surface of the molding object.

  The seed layer 15 is formed, for example, by depositing about 0.5 μm of Cu using sputtering. Before depositing Cu, an intermediate layer such as Cr or Ti may be formed to have a thickness of about 0.1 μm to improve the adhesion.

  The material of the metal film 16 can be appropriately selected according to the function required for the fine mold 1 such as Ni in addition to Cu. Also, the formation method of the metal film 16 may be appropriately selected according to the combination of materials constituting the laminated film, such as electroless plating, electrolytic plating, sputtering, CVD, MIM (Metal Injection Molding).

  Next, the surface of the metal film 16 is planarized. By flattening the surface of the metal film 16, when the sheet-like fine mold 1 is joined to a plate and used, the surface of the molding object is caused by the uneven thickness of each film constituting the fine mold 1. Can prevent swells.

Finally, as shown in FIG. 1E, when the sacrificial mold 12 is removed, a protrusion 18 composed of the film 13 and the base film 14 and a substrate 17 composed of the seed layer 15 and the metal film 16 are formed, and the substrate 17 is diced. When divided, the fine mold 1 is completed. Specifically, for example, by performing reactive dry etching using any gas of CF ₄ , CH ₂ F ₂ , and CH ₃ F, the sacrificial mold 12 made of a single crystal Si wafer is removed. In addition, you may remove the membrane | film | coat 13 after this. For example, the film 13 made of TiN _x may be removed by ion etching using a reactive gas such as CF ₄ or Cl _2, or the film 13 may be removed using ethylenediaminetetraacetic acid or sulfuric acid. When the seed layer 15 is formed of a hard material such as Cr or Ti, it is desirable to remove the exposed portion of the seed layer 15.

  The fine mold 1 manufactured in this way is suitable for hot embossing and nanoimprint because the surface of the protrusion 18 is formed of a hard film made of a refractory metal or a compound of a refractory metal. Further, since the film 13 forming the surface of the protrusion 18 and the base film 14 forming the inside of the protrusion 18 are also divided for each protrusion 18, the film 13 and the base film 14 are formed. This is a structure in which the warp of the fine mold 1 due to the generated stress hardly occurs.

(Second reference form)
Figure 2 is a sectional view showing a second reference embodiment of a method of manufacturing a micro thin mold.
First, as shown in FIG. 2A, a seed layer 21 and a base film 22 for forming a substrate 29 (see FIG. 2E) of the fine mold 2 are deposited on a sacrificial substrate 20 made of a single crystal Si wafer. Quartz, glass, crystallized glass, SiN _x , AlN _x , AlO or the like may be used for the sacrificial substrate 20. The seed layer 21 is formed by, for example, depositing 0.02 μm of Cr on the surface of the sacrificial substrate 20 by sputtering, and subsequently depositing 0.1 μm of Cu by sputtering. CVD or the like may be used to form the seed layer 21. The base film 22 is formed, for example, by depositing 200 μm of Cu on the surface of the seed layer 21 by electrolytic plating. For the base film 22, it is desirable to use a material having a relatively high thermal conductivity among metals such as Cu. A low melting point metal such as tin or solder or a resin may be used for the material of the base film 22 instead of Cu.

  Next, as shown in FIG. 2B, a photoresist is applied to the surface of the sacrificial substrate 20, prebaked and cured, then exposed to a stepper, aligner, electron beam, etc., developed, and postbaked to form a photoresist mask. 23 is formed. The coating thickness of the photoresist is, for example, 100 μm. The pattern of the photoresist mask 11 is set according to the shape of the molding surface of the fine molding mold 2 (see FIGS. 2E and 2F).

  Subsequently, a plurality of through holes 24 are formed in the sacrificial substrate 20 by transferring the pattern of the photoresist mask 23 to the sacrificial substrate 20 by anisotropic etching. As a result, the seed layer 21 is exposed from the through hole 24.

  Next, after removing the photoresist mask 23, a film 25 for forming the protrusions 28 of the fine mold 2 (see FIG. 2F) on the surface of the sacrificial substrate 20 and the surface of the seed layer 21 as shown in FIG. 2C; A base film 26 is deposited. For the film 25 and the base film 26, a material having a hardness higher than that of the base film 22 than that of the seed layer 21 for forming the substrate 29 of the fine mold 2 is used. Specifically, for example, NiW is deposited by 0.5 μm on the surface of the seed layer 21 by CVD, sputtering, or the like to form a coating 25, and then NiW is deposited on the surface of the coating 25 by electrolytic plating, CVD, or the like. 26 is formed. As the material of the protrusion 28, other high melting point metal such as NiMo, NiW, NiFe, CoMo, NiCo or a compound of a high melting point metal may be used.

  Next, as shown in FIG. 2D, the base film 26 and the film 25 are removed by grinding, polishing or the like until the sacrificial substrate 20 is exposed, and the surface of the workpiece is flattened. As a result, both the base film 26 and the film 25 are divided, and even if these films have stress, the micromolding mold 2 is hardly warped depending on the stress. The surface of the workpiece may be flattened using electric discharge machining, sand blasting, a router, or the like.

  Next, as shown in FIG. 2E, the sacrificial substrate 20 is removed, and the substrate 29 composed of the base film 22 and the seed layer 21 is divided by dicing, whereby the fine mold 2 is completed. Thereafter, the film 25 of the protrusion 28 and the exposed portion of the seed layer 21 may be selectively removed by etching as shown in FIG. 2F.

  The micro-molding mold 2 manufactured in this way is suitable for hot embossing and nanoimprinting because the surface of the protrusion 28 is formed of a hard film made of a refractory metal or a compound of a refractory metal. Further, since the high hardness film 25 and the base film 26 are separated, the fine mold 2 is less likely to warp.

(Implementation form)
Figure 3A, 3B, 3C, 3D is a cross-sectional view showing an implementation form of the manufacturing method of the fine mold according to the present invention.
First, as shown in FIG. 3A, an uneven region is formed on the material substrate 30 for forming the substrate 35 of the fine mold 3 (see FIG. 3D), and the protrusion 34 of the fine mold 3 is formed on the uneven region. A seed layer 31, a hard film 32, and a heat conducting film 33 are sequentially deposited. For example, single crystal Si is used for the material substrate 30, and the method for forming the uneven region conforms to the first reference embodiment.

  The seed layer 31 is formed by depositing, for example, 0.5 μm of TiN, TaN or the like having a hardness higher than that of the material substrate 30 on the surface of the material substrate 30 by sputtering, CVD, or the like.

The hard film 32 is formed by depositing, for example, W, Ta, Ti, Mo, TiN, TaN, MoN or the like having a higher hardness than the material substrate 30 on the surface of the seed layer 31 by CVD. When W is deposited by CVD, the crystal structure grows in a columnar shape. Therefore, when the hard film 32 is formed by W deposited by CVD, fine irregularities are formed on the surface of the hard film 32 to provide an anchor effect ( As a result, the adhesion between the hard film 32 and the heat conducting film 33 is improved. The hard film 32 may be formed of NiP, NiW, NiCo, NiFe, NiMn, NiMo, Cr, or the like deposited by electrolytic plating or electroless plating. In this case, pulse plating may be performed in order to accurately control the film thickness. When the hard film 32 is formed by plating, it is desirable to adjust the current density, metal concentration, bath composition, bath temperature, additives, etc. so that fine irregularities are formed on the surface. Further, after forming the hard film 32, fine irregularities may be formed by etching the surface thereof. For example, when NiFe is deposited by electrolytic plating and then wet-etched with a ferric chloride aqueous solution, fine irregularities that provide an anchor effect can be formed on the surface of the hard film 32. The hard film 32 may be deposited by sputtering or MIM. Further, after the hard film 32 is deposited, the surface of the hard film 32 may be flattened by grinding, polishing, or the like.

  The heat conducting film 33 is a film having a function of improving the thermal conductivity of the protrusion 34 of the fine mold 3. For example, the heat conducting film 33 is formed by depositing 200 μm of Cu or the like on the surface of the hard film 32 by electroless plating.

  Next, as shown in FIG. 3C, the surface layers of the heat conducting film 33, the hard film 32, and the seed layer 31 are removed by grinding, polishing, or the like until the material substrate 30 is exposed. As a result, the heat conducting film 33, the hard film 32, and the seed layer 31 are divided, and even if these films are stressed, the micromolding mold 3 is hardly warped depending on the stress.

Next, as shown in FIG. 3D, the heat conductive film 33 and the hard film 32 are removed by removing the surface layer of the material substrate 30 by dry etching mainly containing any gas of CF ₄ , CH ₂ F ₂ , and CH ₃ F. Then, the remaining part of the seed layer 31 is protruded to form a protrusion 34 composed of these films, and the substrate 35 is formed by dividing the material substrate 30 by dicing, whereby the fine mold 3 is completed. At this time, by setting the etching end point shallower than the depth of the recess formed in the material substrate 30, the recess where the bottom surface and the side surface of the protrusion 34 are in close contact with each other as shown in FIG. 3D remains on the surface of the substrate 35. It is desirable. As a result, the bonding strength between the substrate 35 and the protrusion 34 increases.

  The fine mold 3 manufactured in this way is suitable for hot embossing and nanoimprinting because the side surfaces of the protrusions 34 are formed of a hard film. Further, since the hard film 32 and the seed layer 31 are separated, the fine mold 3 is less likely to warp.

( Third reference form)
Figure 3A, 3B, 3C, 3E are sectional views showing a third reference embodiment of a method of manufacturing a micro thin mold.
According to the embodiment, as shown in FIG. 3C, after removing the heat conduction film 33, the hard film 32, and the surface layer of the seed layer 31 by grinding, polishing, or the like until the material substrate 30 is exposed, the heat conduction film 33 is selectively etched. When the material substrate 30 is removed and divided by dicing, the fine mold 4 shown in FIG. 3E is completed.

  In the fine mold 4 manufactured in this way, since the hard film 32 forming the uneven side surface of the molding surface is divided, warping is unlikely to occur.

( 4th reference form)
FIG. 4 is a sectional view showing a fourth reference embodiment of the method for producing a fine mold according to the present invention.

  First, as shown in FIG. 4A, a photoresist is applied to the surface of the material substrate 40, pre-baked and cured, then exposed with a stepper, aligner, electron beam, etc., developed, and post-baked to thereby form a photoresist mask 41. Form. As a result, an uneven region 42 is formed by the surface of the photoresist mask 41 and the surface of the material substrate 40. As the material of the material substrate 40, for example, Cu or Ni may be used, an alloy of Cu or W may be used, or glass, ceramic, or Si may be used.

  Note that a film made of a thermosetting resin, a photo-curing resin, a thermoplastic resin, or the like may be formed on the material substrate 40, and the uneven region 42 may be formed by the pattern of the film. Specifically, the uneven region 42 is formed as follows using, for example, a nanoimprint method. First, a thermosetting resin is applied to the surface of the material substrate, and the thermosetting resin film is heated and cured in a state where the master mold is pressed against the thermosetting resin film. Next, the master mold is peeled from the cured resin film. Subsequently, when the surface layer of the resin film is removed by etching by RIE, the material substrate 40 is exposed, and the uneven region 42 shown in FIG. 4A is formed.

  Next, as shown in FIG. 4B, a hard film 43 is deposited on the material substrate 40 exposed in the uneven region 42. The hard film 43 is formed by depositing a high melting point metal such as NiW, NiMo, NiW, NiFe, CoMo, or NiCo having a higher hardness than the material substrate 40 or a compound of a high melting point metal by electrolytic plating to 20 μm. At this time, since the hard film 43 is deposited in each opening of the photoresist mask 41 independently of each other, even if a strong stress is generated in the hard film 43, the micromolding mold 5 is not easily warped depending on the stress of the hard film 43. .

  Finally, when the photoresist mask 41 is removed and the material substrate 40 is divided by dicing, a protrusion made of the hard film 43 is formed, and the fine mold 5 is completed.

  The micro-molding mold 5 manufactured in this manner is suitable for hot embossing and nanoimprinting because the protrusion on the molding surface is formed by the hard film 43. Since the hard film 43 forming the molding surface is divided, warping is unlikely to occur.

  It should be noted that the present invention is not limited to the above-described embodiment, and it is needless to say that various modifications can be made without departing from the gist of the present invention. For example, in the manufacturing process described above, the film composition, the film forming method, and the like are appropriately selected according to the required function, the combination of film materials, the film thickness, and the like, and are not particularly limited.

Sectional drawing concerning the 1st reference form of this invention. Sectional drawing concerning the 2nd reference form of this invention. Sectional view according to the implementation embodiments and third reference facilities embodiment of the present invention. Sectional drawing concerning the 4th reference form of this invention.

Explanation of symbols

1: fine mold, 2: fine mold, 3: fine mold, 4: fine mold, 5: fine mold, 10: uneven area, 11: photoresist mask, 12: sacrificial mold, 13: film, 14: base film, 15: seed layer, 16: metal film, 17: substrate, 18: protrusion, 20: sacrificial substrate, 21: seed layer, 22: base film, 23: photoresist mask, 24: through hole, 25: film, 26: base film, 28: protrusion, 29: substrate, 30: material substrate, 31: seed layer, 32: hard film, 33: heat conduction film, 34: protrusion, 35: substrate, 40: material Substrate, 41: Photoresist mask, 42: Uneven region, 43: Metal film, 50: Material substrate, 52: Photoresist mask, 54: Thermal conductive film, 55: Seed layer, 56: Hard film, 58: Projection

Claims (2)

A substrate,
A part of the molding surface is formed of a refractory metal or a compound of a refractory metal selected from W, Ta, Ti, Mo , Cr, TiN, TaN, MoN, NiP, NiW, NiCo, NiFe, NiMn, and NiMo. A hard film that is divided,
A plurality of protrusions bonded to the surface of the substrate and formed of the hard film having at least a part of a surface layer having a higher hardness than the surface of the substrate;
With
The hard film forming the protrusion is in close contact with the side surface and the bottom surface of the concave portion on the surface of the substrate.
Fine molding mold. Forming an uneven region on the surface of the material substrate for forming the substrate of the fine mold,
Depositing the hard film for forming the protrusions of the micro-molding mold on the uneven region;
Removing the hard film until the material substrate is exposed;
Forming the protrusion and the substrate by removing a surface layer of the material substrate;
The manufacturing method of the fine mold according to claim 1.

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