JP2008168477A - Method for producing minute molding mold - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make the unevenness of the molding surface of a minute molding mold minute. <P>SOLUTION: In a method for producing the minute molding mold, a shading film for forming the projection of the molding surface on the surface having the unevenness of a sacrifice body is formed so that the film thickness of a part parallel with the side of the recess of the unevenness is equal to the width of a corresponding part of the projection, parts excluding the part parallel with the side of the recess of the unevenness of the shading film are removed to form a translucent substrate joined to the end face of the residual part of the shading film. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing a fine mold.

  Conventionally, as a technique for forming a high-aspect and fine three-dimensional shape at a low cost, a fine forming technique such as hot embossing or nanoimprint using a fine mold is known (see, for example, Patent Document 1). The fine mold can be manufactured using a mother mold that is formed using photolithography.

JP 2004-304097 A

  An object of this invention is to refine | miniaturize the unevenness | corrugation of the molding surface of a fine mold.

  (1) In the method for producing a fine mold for achieving the above object, a light-shielding film for forming a convex portion of a molding surface on a surface having a concave and convex portion of a sacrificial body is parallel to a side surface of the concave portion of the concave and convex portions. The film thickness of the part is formed to be equal to the width of the corresponding part of the convex part, and the remaining part of the light-shielding film is removed by removing the part of the light-shielding film other than the part parallel to the side surface of the concave part. Forming a translucent substrate bonded to the end face of the substrate.

  According to this method, the width of the convex portion of the molding surface of the fine mold can be reduced to the thickness of the light shielding film. That is, the convex part of the molding surface of the fine mold can be formed narrower than the width of the concave part of the surface of the sacrificial body used for forming the molding surface of the fine mold. When the concavo-convex surface of the sacrificial body is formed by photolithography and the surface of the sacrificial body as a mother mold is transferred to form the molding surface of the fine molding mold, the concavo-convex surface of the micro-molding mold is formed by photolithography. It cannot be made finer beyond the resolution limit. However, since it is possible to make the film thickness of the light-shielding film thinner than the resolution limit of photolithography by adjusting the film forming conditions, according to the present invention, the unevenness of the molding surface of the fine molding mold can be made finer than before. it can.

  In the present specification, the molding surface means the surface of a fine molding mold that serves as an interface with the molding object. In addition, the “end face” of the light-shielding film is a relative shape including an intersection line of a relatively wide surface that is substantially parallel to the lower surface of the light-shielding film and an intersection line of the lower surface of the light-shielding film. It means a narrow flat surface.

(2) In a fine mold for achieving the above object, a sacrificial film is formed on the surface of the light-shielding film so as to fill the recesses of the unevenness, and both the sacrificial film and the unevenness of the light-shielding film are formed. It may include removing other than the portion parallel to the side surface of the recess by at least one of grinding and polishing.
In this case, when removing the light-shielding film by at least one of grinding and polishing, it is possible to prevent the light-shielding film from peeling off from the side surface of the concave portion of the sacrificial body and the corners of the end face of the light-shielding film from becoming rough. it can.

(3) The fine mold for achieving the above object may include bonding the light-transmitting substrate to an end surface of the remaining portion of the light-shielding film.
In this case, the manufacturing cost of the mold can be reduced as compared with the case where the translucent substrate is formed by depositing the material.

(4) The fine mold for achieving the above object may include directly bonding the translucent substrate to an end surface of the remaining portion of the light-shielding film.
In this case, no adhesive remains between the light-shielding film constituting the convex portion of the molding surface and the light-transmitting substrate, and compared with the case where the light-shielding film and the light-transmitting substrate are bonded with the adhesive. Bonding strength is increased. Therefore, in this case, it is possible to prevent the position of the convex portion of the molding surface from being shifted due to a temperature change, and the light shielding film from being peeled off from the light transmitting substrate.

(5) In the fine mold for achieving the above object, the light-shielding film may be made of a refractory metal or a compound of a refractory metal.
On the molding surface of the fine mold, the convex portion is more easily damaged than the concave portion. High melting point metals and high melting point metal compounds have higher hardness than low melting point metals such as Cu. Therefore, in this case, since the light-shielding film constituting the convex portion of the molding surface is made of a refractory metal or a compound of a refractory metal, it becomes a fine molding mold that is not easily damaged even when a hard foreign substance is mixed into the molding object. .

(6) In the fine mold for achieving the above object, the light shielding film may be formed by wet plating.
Wet plating has a higher deposition rate than dry plating. Therefore, this method is suitable for reducing the manufacturing cost of the fine mold.

  In the claims, “to the top” means both “without an intermediate on the top” and “with an intermediate on the top” unless there is a technical impediment. To do. 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 embodiment)
Fine Mold and Method for Using the Same FIG. 1 to FIG. 4 are sectional views showing a method for using the fine mold (hereinafter referred to as a stamper) 1 according to the first embodiment of the present invention. The stamper 1 is a mold for molding a photosensitive molding target film 18 as a molding target by optical imprinting.

As shown in FIG. 1, the stamper 1 includes a light-transmitting substrate 22 and a light-shielding film 14, and has a convex portion 101 formed of the light-shielding film 14 on the molding surface.
The translucent substrate 22 is made of low-melting glass. As a material of the translucent substrate 22, any material having sufficient transparency with respect to the exposure wavelength of the photosensitive molding target film 18 may be used. Further, from the viewpoint of durability of the stamper 1, it is desirable that the material has excellent mechanical properties such as hardness and toughness. Accordingly, it is preferable to select glass, quartz, crystallized glass, sapphire, alumina, or the like as the material of the translucent substrate 22.

  The light shielding film 14 is made of NiFe. The material of the light-shielding film 14 is not limited to NiFe, and any material may be used as long as it has a sufficient light-shielding property with respect to the exposure wavelength of the photosensitive molding target film 18. Further, from the viewpoint of durability of the stamper 1, it is desirable that the material has excellent mechanical properties such as hardness and toughness. In particular, since the convex portion of the molding surface is more likely to collide with foreign matter 192 and 191 mixed in the photosensitive molding target film 18 than the translucent substrate 22 constituting the bottom surface of the concave portion, the machine has higher hardness and toughness than the translucent substrate 22. It is desirable that the material has excellent physical properties (for example, a refractory metal or a compound of a refractory metal). For the light-shielding film 14 formed by deposition, it is desirable to select a material having excellent adhesion to the light-transmitting substrate 22 and film formation cost. Therefore, it is desirable to select Ta, Ti, Mo, Cu, TiN, TaN, MoN, NiW or the like as the material of the light shielding film 14. The shape of the light-shielding film 14 is determined by the design of the molding object. For example, if a groove having a width of 2 μm is formed in the photosensitive molding object film 18, it becomes a standing wall having a width of 2 μm. The miniaturization limit of the pattern of the light-shielding film 14 depends on how far the film thickness of the light-shielding film 14 can be reduced. In principle, the pattern can be miniaturized to the atomic level.

  As a material of the photosensitive molding target film 18 that is a molding target, a photo-curable resin such as a negative photoresist or a negative photosensitive polyimide is selected. Foreign substances 191 and 192 may be mixed in the photosensitive molding target film 18 applied on the surface of the support substrate 17.

  As shown in FIG. 2, when the stamper 1 is pressure-bonded to the photosensitive molding target film 18, the foreign substances 191 and 192 are pressed by the support substrate 17 and the stamper 1 depending on the positions where the foreign substances 191 and 192 are mixed. If the mixing position is a position that fits into the concave portion of the molding surface of the stamper 1 like the foreign material 191, the stamper 1 is less likely to receive the reaction force of the foreign material 191 depending on the size of the foreign material 191. On the contrary, when the foreign matter is mixed just under the convex portion of the molding surface of the stamper 1 like the foreign matter 192, the reaction force of the foreign matter reaches the stamper 1. When the reaction force of the foreign matter reaches the stamper 1, the molding surface of the stamper 1 can be deformed if the hardness and toughness of the foreign matter 191 and 192 are higher than that of the stamper 1. In this embodiment, since the convex part of the molding surface is made of NiFe which is a compound of a refractory metal, the molding surface of the stamper 1 is not easily deformed.

  When light such as ultraviolet rays or visible rays is irradiated from the back side of the molding surface of the stamper 1, the photosensitive molding target film 18 is exposed by the light transmitted through the translucent substrate 22. At this time, the region 182 immediately below the light shielding film 14 becomes a shadow of the light shielding film 14. That is, even if exposed from the back side of the molding surface of the stamper 1, the region 182 immediately below the light-shielding film 14 is not exposed and is not cured. The exposed region 181 of the photosensitive molding target film 18 is exposed to light and cured.

  As shown in FIG. 3, when the stamper 1 is separated from the photosensitive molding target film 18, the surface of the photosensitive molding target film 18 to which the molding surface of the stamper 1 is transferred appears. However, since the unexposed area 182 is not cured, the surface of the photosensitive film 18 to which the molding surface of the stamper 1 is transferred is not fixed.

  When the photosensitive molding target film 18 is developed, the unexposed area 182 is removed, and only the photosensitive area 181 remains as shown in FIG. 4, and a through hole 183 is formed in the photosensitive molding target film 18. At this time, the foreign matter 192 mixed in the unexposed area 182 is removed together with the unexposed area 182. The photosensitive molding target film 18 thus molded can be used as an etching or lift-off protective film or as a MEMS structure.

-Manufacturing method of a fine mold First, as shown in FIG. 5, the support substrate 11 is anisotropically etched using the protective film 10 formed on the surface of the support substrate 11 used as a sacrifice body, and the recessed part 110 is formed. Specifically, for example, a photoresist is applied on the surface of the support substrate 11, pre-baked, exposed and developed, and then patterned. Electron beam exposure may be used for patterning the protective film 10. Etching is performed, for example, by reactive dry etching mainly using any gas of CF ₄ , CH ₂ F ₂ , and CH ₃ F. The etching rate between the protective film 10 and the support substrate 11 is about 1: 1, and the recess 110 is formed by etching the support substrate 11 and transferring the sectional shape of the opening of the protective film 10 together with the protective film 10. It may be tapered. Further, the recess 110 can be formed in the support substrate 11 by high-precision machining. The material of the support substrate 11 is selected in consideration of compatibility with a film formed in a subsequent process, mechanical strength during handling, and ease of removal as a sacrificial body.

  Next, as shown in FIG. 6, a seed layer 12 is formed on the surface of the support substrate 11. For example, a seed layer 12 having a thickness of 0.5 μm made of Cr, Ni, NiFe or the like is formed by sputtering. An adhesion layer made of Ti or the like may be formed between the seed layer 12 and the support substrate 11. The seed layer 12 is not necessarily required and can be left as a film that finally forms the convex portion of the molding surface. However, in the present embodiment in which the seed layer 12 is finally removed, the seed layer 12 and the support are supported. A sacrificial body 13 for forming and molding a light-shielding film 14 which is a film constituting the convex portion of the molding surface with the substrate 11 is constituted, and the surface of the seed layer 12 constitutes a concave portion 130 on the surface of the sacrificial body 13. Will do. When the seed layer 12 is not formed, the recess 110 of the support substrate 11 constitutes a recess on the surface of the sacrificial body.

  Next, as shown in FIG. 7, a light shielding film 14 is formed on the surface of the seed layer 12. The film forming condition of the light-shielding film 14 is that the thickness T of the portion parallel to the side surface of the concave portion 130 of the sacrificial body 13 is equal to the width W of the corresponding portion of the convex portion 101 (see FIG. 1) of the molding surface of the stamper 1. Is set to be As a method for forming the light-shielding film 14, a method in which the film thickness is uniform is desirable, for example, electrolytic plating is desirable. Further, since the surface of the formed light-shielding film 14 constitutes the molding surface of the stamper 1, it is desirable to employ a combination of a film-forming method and a material that makes the surface of the light-shielding film 14 smooth. It is desirable to form a film by depositing by plating. When the light-shielding film 14 is formed by electrolytic plating or electroless plating, the throughput is increased compared to the case of forming by CVD or PVD, and the manufacturing cost of the stamper 1 can be reduced. When the light-shielding film 14 is formed by CVD, it becomes easier to form a refractory metal or a refractory metal compound than in the case of electrolytic plating, and the film thickness uniformity is improved.

  Since the width of the convex portion of the molding surface is determined by the film thickness of the light shielding film 14 formed in this way, there is no cost in setting the film forming conditions for reducing the film thickness of the light shielding film 14. By using a high-resolution photoresist or shortening the exposure wavelength, the fine stamper 1 can be manufactured at a lower cost than the method of miniaturizing the surface of the sacrificial body that is a mother mold for manufacturing the stamper 1. It is.

  Next, as shown in FIG. 8, a sacrificial film 15 that fills the recess 130 of the sacrificial body 13 is formed. The sacrificial film 15 may be any material that can be easily removed as a sacrificial film and can withstand grinding or polishing. For example, Cu or the like is selected. The sacrificial film 15 can be formed by electrolytic plating, electroless plating, CVD, sputtering, vapor deposition, or MIM (Metal Injection Molding) after a mold is placed on the upper surface of the sacrificial body 13.

The light-shielding film 14 and the sacrificial film 15 may be repeatedly stacked, and four or more light-shielding films may be formed inside the recess 130 of the sacrificial body 13. In this case, the thickness of the sacrificial film formed between the light-shielding film and the light-shielding film determines the interval between the convex portions of the molding surface. That is, the distance D (see FIG. 1) between the convex portions of the molding surface can also be controlled by the thickness of the sacrificial film.
Note that the sacrificial film 15 is necessarily required if the bonding strength between the light-shielding film 14 and the sacrificial body 13 is high enough that the light-shielding film 14 is not separated from the sacrificial body 13 by at least one of grinding and polishing in the subsequent process. is not.

  Next, as shown in FIG. 9, the light-shielding film 14 together with the sacrificial film 15 is removed by at least one of grinding and polishing until the sacrificial body 13 is exposed. As a result, at least a portion of the light shielding film 14 that protrudes from the recess 130 of the sacrificial body 13 is removed. The depth to be ground or polished should be at least the sacrificial body 13 is exposed, may be a depth at which the portion of the seed layer 12 protruding from the concave portion 110 of the support substrate 11 remains, or is removed to the surface layer of the support substrate 11. It may be deep. In order to make the width of the convex portion of the molding surface uniform, at least one of grinding and polishing is performed to such a depth that a portion where the film thickness of the light-shielding film 14 is not uniform is removed inside the concave portion 130 of the sacrificial body 13. It is desirable.

Next, as shown in FIG. 10, a translucent substrate 22 is bonded to the surface flattened by at least one of grinding and polishing. For example, the translucent substrate 22 made of low-melting glass is thermocompression bonded to a flat surface constituted by the sacrificial body 13, the end face 140 of the light-shielding film 14, and the sacrificial film 15. As for the bonding strength, it is only necessary that the bonding strength between the light-shielding film 14 and the translucent substrate 22 is high, and the bonding strength between the translucent substrate 22 and the sacrificial body 13 is not a problem. Direct bonding other than thermocompression bonding may be used for bonding the translucent substrate 22. By using the direct bonding, the bonding strength between the translucent substrate 22 and the light-shielding film 14 is increased, so that the strength of the stamper 1 is improved. In direct bonding, an adhesive layer is not formed between the light-transmitting substrate 22 and the light-shielding film 14, so that the molding surface is not deformed due to a temperature change or the like.
The translucent substrate 22 may be formed by depositing a translucent material on a flat surface constituted by the sacrificial body 13, the end face 140 of the light-shielding film 14, and the sacrificial film 15. However, it is more advantageous in terms of residual stress and manufacturing cost to construct the translucent substrate 22 from a bulk material.

  Next, as shown in FIG. 11, the sacrificial body 13 is removed from at least one of grinding and polishing from the back surface of the sacrificial body 13 (that is, the back side of the surface on which the light-shielding film 14 is formed). Only the part parallel to the side surface of the recess is left, and the other part of the light-shielding film 14 is removed. In order to make the width of the convex part of the molding surface uniform, it is desirable to carry out at least one of grinding and polishing to a depth at which the non-uniform thickness of the light-shielding film 14 is removed inside the concave part of the sacrificial body 13. .

  Next, as shown in FIG. 12, the remaining portion of the sacrificial film 15 is selectively removed. For example, the sacrificial film 15 made of Cu is removed by wet etching using Enstrip C (registered trademark) manufactured by Elmex Corporation.

  Next, as shown in FIG. 13, the remaining portion of the support substrate 11 is selectively removed by etching. When the sacrificial film 15 and the support substrate 11 are made of the same material, the sacrificial film 15 and the support substrate 11 are removed simultaneously.

Next, when the seed layer 12 is removed by etching, the stamper 1 shown in FIG. 1 is completed. Specifically, for example, the seed layer 12 made of Cr is removed by wet etching with ceric ammonium nitrate.
In this embodiment, the seed layer 12 is removed as a sacrificial body, but the state shown in FIG. 13 where the seed layer 12 remains is a completed state, and the seed layer 12 and the light-shielding film 14 constitute a convex portion of the molding surface. May be. In this case, the bonding strength between the translucent substrate 22 and the seed layer 12 is preferably higher.

(Second embodiment)
14 and 15 are cross-sectional views showing a second embodiment of the method for manufacturing the stamper 1.
In this embodiment, the sacrificial body 21 is constituted by the support substrate 11 and the sacrificial film 20 as shown in FIG. 14 or the support substrate 11, the sacrificial film 20 and the seed layer 12 as shown in FIG. That is, when the stamper 1 is completed by removing the seed layer 12, the uneven protrusions of the sacrificial body 21 are constituted by the sacrificial film 20. The sacrificial film 20 is made of Cu or the like patterned by photolithography and electrolytic plating, electroless plating, or etching. When the support substrate 11 is made of an insulating material, a seed layer may be formed on the surface of the support substrate 11 before forming the sacrificial film 20 in order to form the sacrificial film 20 by wet plating.
After the sacrificial body 21 is formed, the stamper 1 can be manufactured by performing the same process as in the first embodiment.

(Other embodiments)
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, the materials, dimensions, film forming methods, and pattern transfer methods shown in the above embodiments are merely examples, and descriptions of addition and deletion of processes and replacement of process orders that are obvious to those skilled in the art are omitted. ing.

It is sectional drawing concerning 1st embodiment of this invention. It is sectional drawing concerning 1st embodiment of this invention. It is sectional drawing concerning 1st embodiment of this invention. It is sectional drawing concerning 1st embodiment of this invention. It is sectional drawing concerning 1st embodiment of this invention. It is sectional drawing concerning 1st embodiment of this invention. It is sectional drawing concerning 1st embodiment of this invention. It is sectional drawing concerning 1st embodiment of this invention. It is sectional drawing concerning 1st embodiment of this invention. It is sectional drawing concerning 1st embodiment of this invention. It is sectional drawing concerning 1st embodiment of this invention. It is sectional drawing concerning 1st embodiment of this invention. It is sectional drawing concerning 1st embodiment of this invention. It is sectional drawing concerning 2nd embodiment of this invention. It is sectional drawing concerning 2nd embodiment of this invention.

Explanation of symbols

1: Stamper, 10: Protective film, 11: Support substrate, 12: Seed layer, 13: Sacrificial body, 14: Light-shielding film, 15: Translucent substrate, 15: Sacrificial film, 17: Support substrate, 18: Photosensitive Film: 20: sacrificial film, 21: sacrificial body, 101: convex part, 110: concave part, 130: concave part, 140: end face, 181: photosensitive area, 182: unexposed area, 183: through hole, 191: Foreign object, 192: Foreign object

Claims (6)

The light-shielding film for forming the convex portion of the molding surface on the surface of the sacrificial body having the unevenness is such that the film thickness of the portion parallel to the side surface of the concave portion of the unevenness is equal to the width of the corresponding portion of the convex portion. Formed into
Remove the portion of the light-shielding film other than the portion parallel to the side surface of the recess,
Forming a translucent substrate bonded to the end face of the remaining part of the light-shielding film;
The manufacturing method of the fine mold which contains this. Forming a sacrificial film on the surface of the light-shielding film to fill the recesses of the irregularities;
Both the sacrificial film and the unevenness of the light-shielding film are removed by at least one of grinding and polishing other than the portion parallel to the side surface of the recess,
The manufacturing method of the fine shaping | molding mold of Claim 1 including this. Bonding the translucent substrate to the end face of the remaining part of the light-shielding film;
The manufacturing method of the fine shaping | molding mold of Claim 1 or 2 including this. Bonding the light-transmitting substrate directly to the end face of the remaining part of the light-shielding film;
The manufacturing method of the fine shaping | molding mold of Claim 3 including this. The light-shielding film is made of a refractory metal or a refractory metal compound,
The manufacturing method of the fine mold according to any one of claims 1 to 4. Forming the light-shielding film by wet plating;
The manufacturing method of the fine shaping | molding mold as described in any one of Claim 1 to 5 including this.

Images