JP2009194170A - Micro pattern forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a micro pattern forming method which removes a residue after a mold pressure without lowering a line width accuracy, and forms a micro pattern accurately. <P>SOLUTION: A coating film (first film 12) having a siloxane coupling is formed on a substrate 11, and a mold 13 is pressed to this first film 12 at a room temperature to transfer the micro pattern thereon. The first film 12 is cured to form a thin film (second film 14), and after the mold 13 is removed, a metal thin film 15 is formed only on a projection part 14a of the pattern by an oblique vapor deposition method. Then, this metal thin film 15 is used as a mask to etch a recess part 14b, thereby removing a residue. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fine pattern forming method for forming a fine pattern of a thin film using a nanoimprint method.

  As one method for forming a fine pattern on a substrate, there is a nanoimprint method in which a resin material is applied to a substrate and a pattern engraved in a mold (mold) is transferred to the applied film. In this nanoimprint method, a thermoplastic polymer such as PMMA (methyl methacrylate resin) is used as a resin material.

  However, in the nanoimprint method using this type of material, heating is required when transferring a fine pattern by pressing a mold, so that pattern collapse occurs due to temperature changes during cooling after transfer, and line width accuracy is improved. There was a problem of lowering. There is also a problem that work efficiency is poor because heating and cooling steps are required.

  In order to solve such problems, conventionally, for example, after a solution containing a siloxane component is applied to the surface of a substrate, the mold is pressed against the coating film before the solvent is volatilized and the curing is completed. There has been proposed a room temperature nanoimprint method in which a nano-sized SiO2 pattern can be formed by removing a mold after curing (Patent Document 1).

Japanese Patent Laid-Open No. 2003-100609

  However, in this room temperature nanoimprint method, after the SiO2 fine pattern is formed, the residue increases in the embossed portion. Therefore, it is necessary to remove this residue by etching, for example, RIE (Reactive Ion Etching), but there is a problem that the line width accuracy of the pattern shape is lowered during the RIE process.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a fine pattern forming method capable of removing residues without reducing line width accuracy and forming a highly accurate fine pattern. Is to provide.

  In the fine pattern forming method of the present invention, a solution having a siloxane bond is applied on a substrate to form a first film, and a mold having a fine pattern is pressed against the first film, thereby transferring the fine pattern. A step of curing the first film to form a second film, and then removing the mold from the second film; and forming a metal film on the upper surface of the convex portion in the fine pattern of the second film And a step of performing etching using the metal film as a mask, selectively removing the recesses in the fine pattern of the second film, and exposing the surface of the substrate.

  In the fine pattern forming method of the present invention, after transfer of the fine pattern, a metal film is formed on the upper surface of the convex portion in the fine pattern of the second film, for example, by oblique vapor deposition, and using this metal film as a mask, Etching of the concave portion is performed in a state where the convex portion of the fine pattern is covered. Thereby, the concave portions (residues) in the fine pattern of the second film are removed without reducing the line width accuracy.

  According to the fine pattern forming method of the present invention, after transferring the fine pattern, a metal film is formed on the surface of the convex part in the fine pattern of the second film, and the concave part is etched using this metal film as a mask. Therefore, the pattern change at the time of residue processing can be prevented, and a fine pattern can be formed with high accuracy. In addition, since the metal film is formed on the uppermost surface of the convex portion of the fine pattern, the selection ratio with the thin film to be patterned can be adjusted by selecting the type of metal.

  Hereinafter, a fine pattern forming method according to an embodiment of the present invention will be described with reference to FIGS. 1 (A) to (C) and FIGS. 2 (A) to (C).

  First, as shown in FIG. 1A, a solution is applied to the surface of, for example, a glass substrate 11 by, eg, spin coating to form a first film (coating film) 12. The solution here contains, for example, a component having a siloxane bond and a solvent containing at least one of alcohol, ester, and ketone. The component having a siloxane bond is, for example, polyhydrogensilsesquioxane, and for example, organ silica can be used. Examples of the solvent include 2-methyl-4-pentanone. By using such a solution, a heating / cooling process becomes unnecessary in the pattern transfer process described later, and pattern collapse in this pattern transfer process is suppressed.

  Next, as shown in FIG. 1B, a mold 13 made of, for example, a nickel (Ni) substrate or a quartz substrate and having a predetermined fine pattern formed thereon is pressed against the surface of the first film 12 at room temperature. Then, the fine pattern is transferred to the first film 12. At this time, a fine pattern having, for example, a concave portion having a line width w = 200 nm and a convex portion having a height h = 100 nm is transferred to the first film 12.

  Subsequently, after the fine pattern is cured by evaporation and hydrolysis of the solvent in the first film 12, the mold 13 is removed from the substrate 11. As a result, as shown in FIG. 1C, a thin film (second film 14) including a siloxane bond and having an uneven fine pattern is formed on the substrate 11.

  Next, as shown in FIG. 2A, the upper surface of the convex portion 14a of the fine pattern of the second film 14 is made of metal by an oblique deposition method using an EB (Electron Beam) deposition machine, for example. Cover with thin film 15. Examples of the material for the metal thin film include aluminum (Al), chromium (Cr), titanium (Ti), nickel, or a combination thereof.

Here, the critical angle θ0 of oblique deposition is expressed by the following equation using the line width w of the concave portion 14b and the height h of the convex portion 14a.
θ0 = tan ⁻¹ h / w
Therefore, by setting the vapor deposition angle θ to be equal to or smaller than the critical angle θ0, the metal thin film 15 can be deposited on the upper surface of the fine pattern convex portion 14a without being deposited on the bottom portion of the fine pattern concave portion 14b. Thereby, only the residue of the recessed part 14b can be selectively removed in the residue process process mentioned later, and pattern collapse can be prevented.

  Next, as shown in FIG. 2B, using the metal thin film 15 as a mask, the residue 16 in the concave portion 14b of the fine pattern is selectively removed by, for example, CHF3 RIE, and the surface of the substrate 11 is removed. Expose. At this time, the etching is performed under such a condition that only the second film 14 is removed, so that the convex portion 14a covered with the metal thin film 15 remains without being removed. Thereby, residue processing can be performed without changing the pattern line width. The selection ratio between the metal thin film 15 and the second film 14 to be patterned can be adjusted by appropriately selecting the type of the metal thin film 15.

  Next, as shown in FIG. 2C, the metal thin film 15 is removed by wet etching, for example, and the upper surface of the convex portion 14a of the fine pattern of the second film 14 is exposed. Through the above steps, a thin film (second film 14) having a precise fine pattern is formed.

  As described above, in this embodiment, after transferring the fine pattern, when removing the residue in the pressed portion of the mold 13, the upper surface of the convex portion 14 a of the fine pattern is previously covered with the metal thin film 15, and this is used as a mask. Since the etching is performed, a change in the line width of the pattern during the residue treatment can be suppressed, and a fine pattern can be formed with high accuracy.

  In the present embodiment, the first film 12 is formed from a coating film having a siloxane bond, and the fine pattern is transferred to the first film 12. Therefore, the transfer is performed at room temperature without performing the heating / cooling process. Therefore, there is no pattern collapse at the time of pattern transfer, and the fine pattern of the mold can be transferred with high accuracy. Therefore, by applying this method, a quantum device such as a single electron transistor can be manufactured.

  Note that after the first film (coating film) 12 is formed, heating (pre-baking) may be performed before pattern transfer to reduce the thickness of the first film (coating film) 12. When the heating temperature exceeds 150 ° C., the first film 12 is cured, and subsequent pattern transfer becomes difficult. Therefore, the heating temperature is 150 ° C. or less, preferably 50 ° C. or less.

Specific examples will be described below.
(Example 1)
First, polyhydrogensilsesquioxane was dissolved in 2-methyl-4-pentanone and applied onto a glass substrate by spin coating. Next, a nickel mold having a fine pattern was pressed against the coating film (first film) on the substrate to transfer the fine pattern. Subsequently, after the coating film was cured by evaporation and hydrolysis of the solvent in the coating film, the mold was removed from the coating film. Next, an aluminum film is formed on the upper surface of the convex portion of the fine pattern by an oblique evaporation method using an EB vapor deposition machine, and this aluminum film is used as a mask to perform RIE etching of CHF3 to remove the residue and to remove the surface of the substrate. Exposed. Finally, the mask (aluminum film) was removed by wet etching. As a result, a thin film (second film) having a fine pattern with no pattern change was obtained.

(Example 2)
After forming the coating film in the same manner as in Example 1, pre-baking was performed at a temperature of 50 ° C. before transferring the fine pattern. Other steps were the same as in the example. Also in Example 2, a thin film having a high-precision fine pattern without pattern change was obtained.

It is sectional drawing showing the formation method of the fine pattern which concerns on one embodiment of this invention for every process. FIG. 2 is a cross-sectional view illustrating a process following FIG. 1.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Board | substrate, 12 ... 1st film | membrane (coating film), 13 ... Mold, 14 ... 2nd film | membrane (thin film), 14a ... Convex part, 14b ... Concave part, 15 ... Metal thin film (mask), 16 ... Residue.

Claims (8)

Applying a solution having a siloxane bond on a substrate to form a first film;
Pressing a mold having a fine pattern against the first film, and transferring the fine pattern;
Removing the mold from the second film after curing the first film to form a second film;
Forming a metal film on the upper surface of the convex portion in the fine pattern of the second film;
Etching the metal film as a mask, selectively removing the recesses in the fine pattern of the second film, and exposing the surface of the substrate. The said solution contains at least 1 sort (s) among alcohol, ester, and a ketone as a solvent with the component which has a siloxane bond. The fine pattern formation method of Claim 1 characterized by the above-mentioned. The fine pattern forming method according to claim 2, wherein the first film is cured by evaporation and hydrolysis of a solvent in the solution. The fine pattern forming method according to claim 1, wherein the fine pattern is transferred to the first film in an atmosphere at room temperature. The method for forming a fine pattern according to claim 1, wherein the first film is formed of polyhydrogensilsesquioxane. The fine pattern forming method according to claim 1, wherein the first film is formed on the substrate, prebaked at a temperature of 150 ° C. or lower, and then the fine pattern is transferred by the mold. The fine pattern forming method according to claim 1, wherein the metal film is formed by an oblique vapor deposition method using at least one kind of metal of aluminum, chromium, titanium, and nickel. The method for forming a fine pattern according to claim 1, further comprising a step of removing the metal film after selectively removing a recess in the fine pattern of the second film.

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