Methods of fabricating nanoimprint stamp

A method of fabricating a nanoimprint stamp includes forming a resist pattern having a nano size width on a stamp substrate by performing imprint processes repeatedly. In the imprint processes, resist layers that are selectively etched are sequentially used. The stamp substrate is etched using the resist pattern as an etch mask.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. §119 to Korean Patent Application No. 10-2011-0001090, filed on Jan. 5, 2011, in the Korean Intellectual Property Office (KIPO), the disclosure of which is incorporated herein in its entirety by reference.

BACKGROUND

Example embodiments relate to methods of fabricating nanoimprint stamps with a fine structure.

2. Description of the Related Art

In a nano imprinting process, after forming a pattern having a desired shape on a surface of a stamp made of a hard material, the pattern is repeatedly copied by pressing the stamp on an object made of a relatively soft material.

Conventionally, photolithography or e-beam lithography is mainly used as a method of obtaining a high resolution and high density pattern. However, according to these methods, it is difficult to manufacture a pattern having a size of 20 nm or less since scattered photons or electrons affect regions outside an exposed region.

SUMMARY

Provided are methods of fabricating nanoimprint stamps by using a multi-patterning method including an implant process.

In example embodiments, a method of fabricating a nanoimprint stamp may include forming a first resist layer on a stamp substrate, pressing an imprint stamp onto the first resist layer to form a first resist pattern, the imprint stamp including a first pattern that is transferred onto the first resist layer when the imprint stamp is pressed onto the first resist layer, forming a second resist layer on the first resist pattern, pressing the imprint stamp onto the second resist layer to form a second resist pattern, the imprint stamp transferring the first pattern onto second resist layer when the imprint stamp is pressed onto the second resist layer, forming a third resist pattern by etching the first resist pattern using the second resist pattern as an etch mask, and etching the stamp substrate using the third resist pattern as an etch mask.

In example embodiments, a method of fabricating a nanoimprint stamp may include forming a first resist layer on a stamp substrate, pressing a first imprint stamp having a first pattern onto the first resist layer to form a first resist pattern, the first pattern being transferred onto the first resist layer when the first imprint stamp is pressed onto the first resist layer, forming a second resist layer having a height substantially equal to that of the first resist pattern, pressing a second imprint stamp having a second pattern onto the second resist layer to form a second resist pattern, the second pattern being transferred onto the second resist layer when the second imprint stamp is pressed onto the second resist layer, the second pattern including a convex unit having a width narrower than that of a convex unit of the first pattern, forming a third resist pattern by selectively etching the first resist pattern, and etching the stamp substrate using the third resist pattern as an etch mask.

In example embodiments, a method of fabricating a nanoimprint stamp may include forming a first resist layer on a stamp substrate, pressing a first imprint stamp having a first pattern onto the first resist layer to form a first resist pattern, the first pattern being transferred onto the first resist layer when the first imprint stamp is pressed onto the first resist layer, forming a second resist layer covering the first resist pattern, pressing a second imprint stamp having a second pattern onto the second resist layer to form a second resist pattern, the second pattern being transferred onto the second resist layer when the second imprint stamp is pressed onto the second resist layer, the second pattern having a convex unit with a width greater than that of a convex unit of the first pattern, the convex unit of the second imprint stamp being formed to correspond to the convex unit of the first pattern, forming a third resist pattern by selectively etching the first resist pattern, and forming a third resist pattern on the stamp substrate by etching an entire surface of the third resist pattern.

In example embodiments, a method of fabricating a nanoimprint stamp may include forming a first resist layer on a stamp substrate, forming a first resist pattern by pressing a first imprint stamp onto the first resist layer, the imprint stamp having a first pattern including a plurality of convex units spaced at a first pattern width, forming a second resist layer on the second resist pattern, forming a second resist pattern by pressing one of the first imprint stamp and a second imprint stamp onto the second resist layer, the second imprint stamp having a second pattern including a plurality of convex units spaced at a second pattern width, forming an imprint stamp having a third pattern by etching the first and second resist patterns, the third pattern having a pattern width smaller than the first pattern width.

According to example embodiments, there is provided a method of fabricating a nanoimprint stamp. In example embodiments, the method includes forming a first resist layer on a stamp substrate, forming a first resist pattern by transferring a first pattern onto the first resist layer by performing an imprint process using an imprint stamp on which the first pattern is formed, forming a second resist layer covering the first resist pattern on the stamp substrate, forming a second resist pattern by transferring the first pattern onto the second resist layer by performing an nanoimprint process using the nanoimprint stamp, forming a third resist pattern by etching the first resist pattern using the second resist pattern as an etch mask, and etching the stamp substrate using the third resist pattern as an etch mask.

The first resist layer and the second resist layer may be formed of materials having different etch selectivity with respect to each other.

One of the first resist layer and the second resist layer may be formed of an acrylate group polymer or a urethane group polymer, and the other may be formed of an organic-inorganic polymer.

The organic-inorganic polymer may be an acrylate group polymer or a urethane group polymer that contains silicon.

The forming of the first resist pattern may include exposing an upper surface of the stamp substrate.

The forming of the second resist pattern may include aligning a convex unit of the first pattern to be placed over a convex unit of the first resist pattern.

The forming of the second resist pattern may include exposing an upper surface of the first resist pattern.

The forming of the third resist pattern may further include selectively etching the second resist pattern.

The method may further include repeatedly performing the forming of the second resist layer, the forming of the second resist pattern and the forming of the third resist pattern after performing the forming of the third resist pattern.

In example embodiments, a plurality of the forming of the second resist patterns may comprise forming a plurality of the first patterns on a corresponding resist layer with an equal distance.

In accordance with example embodiments, a method of fabricating a nanoimprint stamp is provided. In example embodiments, the method may include forming a first resist layer on a stamp substrate, forming a first resist pattern by transferring a first pattern onto the first resist layer by performing an imprint process using a first imprint stamp on which the first pattern is formed, forming a second resist layer having a height equal to that of the first resist pattern on the stamp substrate, forming a second resist pattern by transferring a second pattern onto the second resist layer by performing an imprint process using a second imprint stamp on which the second pattern having a convex unit having a width narrower than that of a convex unit of the first pattern is formed, forming a third resist pattern by selectively etching the first resist pattern, and etching the stamp substrate using the third resist pattern as an etch mask.

A pattern width of the second pattern may be substantially the same as a pattern width of the first pattern.

The forming of the second resist layer may further include forming the second resist layer covering the first resist pattern on the stamp substrate and exposing an upper surface of the first resist pattern by etching an entire surface of the second resist layer.

In accordance with example embodiments, there is provided a method of fabricating a nanoimprint stamp. In example embodiments, the method of fabricating the nanoimprint stamp may include forming a first resist layer on a stamp substrate, forming a first resist pattern by transferring a first pattern onto the first resist layer by performing an imprint process using a first imprint stamp on which the first pattern is formed, forming a second resist layer covering the first resist pattern on the stamp substrate, forming a second resist pattern by transferring a second pattern of a second imprint stamp onto the second resist layer by performing an imprint process using the second imprint stamp on which the second pattern having a convex unit having a width greater than that of a convex unit of the first pattern, the convex unit of the second imprint stamp being formed to correspond to the convex unit of the first pattern, forming a third resist pattern by selectively etching the first resist pattern, and transferring the third resist pattern onto the stamp substrate by etching an entire surface of the third resist pattern.

The forming of the second resist pattern may include pressing a convex unit of the second resist pattern to contact an upper surface of the first resist pattern.

DETAILED DESCRIPTION

Example embodiments will be described more fully hereinafter with reference to the accompanying drawings, in which example embodiments are shown. The present invention may, however, be embodied in many different forms and should not be construed as limited to example embodiments as set forth herein. Rather, example embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present invention to those skilled in the art. In the drawings, the sizes and relative sizes of layers and regions may be exaggerated for clarity.

Reference will now be made in detail to example embodiments as illustrated in the accompanying drawings. In the drawings, the thicknesses of layers and regions are exaggerated for clarity and like reference numerals refer to the like elements throughout.

FIGS. 1A through 1Hare schematic cross-sectional views sequentially showing a method of fabricating a nanoimprint stamp according to example embodiments.

Referring toFIG. 1A, a first resist layer120may be formed on a stamp substrate110for fabricating a nanoimprint stamp. The stamp substrate110may be formed of a hard material, for example, quartz or glass. The first resist layer120may be formed by spin coating an optical hardening resin or a thermal hardening resin. However, example embodiments are not limited spin coating as a method for forming the first resist layer120.

In example embodiments, an imprint stamp130having a first pattern132is prepared. The first pattern132may include a convex unit132aand a concave unit132b. The imprint stamp130may be formed of glass or quartz, though example embodiments are not limited thereto. The imprint stamp130may be formed to have a pattern width W1greater than a pattern width (for example, 20 nm) of a pattern to be formed on the stamp substrate110. Therefore, the imprint stamp130may be formed by using a conventional e-beam lithography method, a laser interference lithography method, or an optical lithography method. The pattern width W1of the first pattern132may be an integer multiple of a pattern width of a pattern to be formed on the stamp substrate110.

Referring toFIG. 1B, a first resist pattern122may be formed by transferring the first pattern132to the first resist layer120through an imprint process in which the imprint stamp130is pressed onto the first resist layer120. According to the material used to form the first resist layer120, the first resist layer120may be hardened by applying heat or irradiating ultraviolet rays to harden the polymer that constitutes the first resist layer120.

Referring toFIG. 1C, the imprint stamp130may be separated from the stamp substrate110. Accordingly, a surface of the stamp substrate110may be exposed. If a portion of the first resist layer120remains on a first surface110aof the stamp substrate110was contacted by the first pattern132, the first surface110aof the stamp substrate110may be exposed by etching the entire surface of the first resist pattern122. The first resist pattern122has a second pattern (a concave pattern)124opposite to the first pattern132. The second pattern124may have a convex unit124aand a concave unit124b, and may have a pattern width W2the same as the pattern width W1of the first pattern132.

Referring toFIG. 1D, a second resist layer140covering the first resist pattern122may be formed on the stamp substrate110by using a coating method. The second resist layer140may be formed of a material having different etching characteristics from the first resist layer120. For example, the first resist layer120may be formed of an organic group material, for example, an acrylate group polymer or a urethane group polymer, and the second resist layer140may be formed of an organic-inorganic polymer. The organic-inorganic polymer may be a urethane group polymer or an acrylate group polymer that contains silicon.

Alternatively, the first resist layer120may be formed of an organic-inorganic polymer, and the second resist layer140may be formed of an acrylate group polymer or a urethane group polymer. The convex unit132aof the first pattern132of the imprint stamp130may be arranged to be placed above the convex unit124aof the second pattern124of the first resist pattern122by laterally moving the imprint stamp130which was separated upward from the stamp substrate110.

Referring toFIG. 1E, the first pattern132may be arranged to be placed on the center of the second pattern124. Since this lateral moving is a fine movement, the fine movement and alignment method of a substrate in the conventional semiconductor process can be used. Afterwards, a second resist pattern142may be formed by performing a second imprint process as the same process described above. The second resist pattern142may have a third pattern144having a pattern width W3equal to the pattern width W1of the first pattern132. The third pattern144may include a convex unit144aand a concave unit144b.

Referring toFIG. 1F, the imprint stamp130may be separated from the stamp substrate110. When a portion of the second resist layer140remains on a second surface122aof the first resist pattern122that was contacted by the convex unit132aof the first pattern132, the second surface122aof the first resist pattern122may be exposed by etching the entire surface of second resist pattern142.

An upper surface of the stamp substrate110may be exposed by selective etching the first resist pattern122exposed in the concave unit144bof the third pattern144using the second resist pattern142as an etch mask. When the first resist pattern122is formed of an acrylate group polymer or a urethane group polymer, the first resist pattern122exposed through the second resist pattern142may be selectively etched by a dry strip method using oxygen plasma.

Referring toFIG. 1G, when the second resist pattern142is removed, a third resist pattern126remains on the stamp substrate110. When the second resist pattern142is formed of an organic-inorganic polymer, the second resist pattern142may be selectively removed by dry etching using an etch gas that contains oxygen and fluoride. The third resist pattern126has a pattern width W4smaller than the pattern width W1of the first pattern132. InFIG. 1G, the pattern width W4is half the size of the pattern width W1.

Referring toFIG. 1H, the stamp substrate110may be etched using the third resist pattern126as an etch mask, and the third resist pattern126may be removed using a conventional lift-off process. As a result a nanoimprint stamp112is formed by transferring the third resist pattern126.

In example embodiments, a single imprint stamp130may be used twice. However, example embodiments are not limited thereto. For example, inFIG. 1G, after additionally forming a third resist layer using a material that can be etched selectively with the first resist layer120like the second resist layer140, as described above, the third implant process may be repeated, and if the second implant process and the third implant process are performed with an equal distance with respect to the second pattern124, the pattern width W1can be reduced as many times as the number of nanoimprint processes. A nanoimprint stamp may be fabricated by transferring a resultant pattern on the stamp substrate110as described above.

According to the method of fabricating a nanoimprint stamp according to example embodiments, a pattern width can be reduced by an integer multiple by repeatedly using an imprint stamp having the pattern. Accordingly, a nanoimprint stamp having a nano-width of 20 nm or less may be readily fabricated by using an imprint stamp having a pattern width of 20 nm or above.

FIGS. 2A through 2Gare schematic cross-sectional views sequentially showing a method of fabricating a nanoimprint stamp according to example embodiments.

Referring toFIG. 2A, a first resist layer220may be formed on a stamp substrate210for fabricating a nanoimprint stamp. The stamp substrate210may be formed of a hard material, for example, quartz or glass, though example embodiments are not limited thereto. The first resist layer220may be formed by spin coating an optical hardening resin or a thermal hardening resin. However, example embodiments are not limited spin coating as a method for forming the first resist layer220.

In example embodiments, an imprint stamp230on which a first pattern232is formed may be prepared. The first pattern232may include a convex unit232aand a concave unit232b, and may have a pattern width W1. In example embodiments, the first pattern232may or may not be predetermined. The imprint stamp230may be formed to have a pattern width W1greater than a pattern width (for example, 20 nm) of a pattern to be formed on the stamp substrate210. Therefore, the imprint stamp230may be formed by using a conventional e-beam lithography method, a laser interference lithography method, or an optical lithography method. The pattern width W1of the first pattern232may be an integer multiple of the pattern width of a pattern to be formed on the stamp substrate210.

Referring toFIG. 2B, a first resist pattern222may be formed by transferring the first pattern232to the first resist layer220through an imprint process in which the imprint stamp230is pressed onto the first resist layer220. According to the material used to form the first resist layer220, the first resist layer220may be hardened by applying heat or irradiating ultraviolet rays to harden the polymer that constitutes the first resist layer220.

Referring toFIG. 2C, the imprint stamp230may be separated from the stamp substrate210. Accordingly, the first resist pattern222may have a second pattern224opposite to the first pattern232. The second pattern224includes a convex unit224aand a concave unit224b. The second pattern224has a pattern width W2equal to the pattern width W1of the first pattern232.

Referring toFIG. 2D, a second resist layer240covering the first resist pattern222may be formed on the stamp substrate210by using a spin coating method. The second resist layer240may be formed to have the same height as the first resist pattern222or may be formed to be higher than the first resist pattern222as shown inFIG. 2Dso as to slightly cover the convex unit224aof the first resist pattern222. The second resist layer240may be formed of a material having different etching characteristics from the first resist layer220. For example, the second resist layer220may be formed of an organic group material, for example, an acrylate group polymer or a urethane group polymer, and the second resist layer240may be formed of an organic-inorganic polymer. The organic-inorganic polymer may be an acrylate group polymer or a urethane group polymer that contains silicon.

Alternatively, the first resist layer220may be formed of an organic-inorganic polymer, and the second resist layer240may be formed of an acrylate group polymer or a urethane group polymer.

A portion of the second resist layer240higher than the first resist pattern222may be is removed by etching an entire surface of the second resist layer240from above the second resist layer240.

Another imprint stamp250for performing an imprint process onto the second resist layer240may be prepared. The imprint stamp250may include a third pattern252having a pattern width W3as the same as the pattern width W1of the first pattern232on a surface thereof. The third pattern252may include a convex unit252aand a concave unit252b. The convex unit252aof the third pattern252may have a width W4smaller than the pattern width W1of the first pattern232.

Referring toFIG. 2E, the convex unit252aof the third pattern252of the imprint stamp250may be placed in the middle of the concave unit224bof the second pattern224of the first resist pattern222(refer toFIG. 2D). Afterwards, by performing the same process described above, a second resist pattern242may be formed. The second resist pattern242may be formed on the same layer with the first resist pattern222.

Referring toFIG. 2F, after separating the imprint stamp250from the stamp substrate210, an upper surface of the stamp substrate210may be exposed by selectively etching the first resist pattern222. The second resist pattern242may remain on the stamp substrate210.

Referring toFIG. 2G, the stamp substrate210may be etched using the second resist pattern242as an etch mask, and the second resist pattern242may be removed using a conventional lift-off process. A nanoimprint stamp212as a resultant product is a stamp onto which the second resist pattern242is transferred.

According to example embodiments, a nanoimprint stamp having a nano-width can be readily fabricated by sequentially using two implant stamps having patterns different from each other.

FIGS. 3A through 3Gare schematic cross-sectional views sequentially showing a method of fabricating a nanoimprint stamp according to example embodiments.

Referring toFIG. 3A, a first resist layer320may be formed on a stamp substrate310for fabricating a nanoimprint stamp. The stamp substrate310may be formed of a hard material, for example, quartz or glass. The first resist layer320may be formed by spin coating an optical hardening resin or a thermal hardening resin.

In example embodiments, an imprint stamp330on which a first pattern332may be formed is prepared. The first pattern332may include a convex unit332aand a concave unit332b, and may have a pattern width W1. In example embodiments, the first pattern332may or may not be predetermined. The imprint stamp330may be formed of quartz or glass, and may be formed to have the pattern width W1greater than a pattern width (for example, 20 nm) of a pattern to be formed on the stamp substrate310. Therefore, the imprint stamp330may be formed by using a conventional e-beam lithography method, a laser interference lithography method, or an optical lithography method. The pattern width W1of the first pattern332may be an integer multiple of the pattern width of a pattern to be formed on the stamp substrate310.

Referring toFIG. 3B, a first resist pattern322may be formed by transferring the first pattern332to the first resist layer320through an imprint process in which the imprint stamp330is pressed onto the first resist layer320. According to the material used to form the first resist layer320, the first resist layer320may be hardened by applying heat or irradiating ultraviolet rays to harden the polymer that constitutes the first resist layer320.

Referring toFIG. 3C, the imprint stamp330may be separated from the stamp substrate310. Accordingly, the first resist pattern322may have a second pattern (convex pattern)324opposite to the first pattern332. The second pattern324may have a pattern width W2equal to the pattern width W1of the first pattern332.

Referring toFIG. 3D, a second resist layer340covering the first resist pattern322may be formed on the stamp substrate310by using a spin coating method. The second resist layer340may be formed of a material having different etching characteristics from the first resist layer320. For example, the first resist layer320may be formed of an organic group material, for example, an acrylate group polymer or a urethane group polymer, and the second resist layer340may be formed of an organic-inorganic polymer. The organic-inorganic polymer may be an acrylate group polymer or a urethane group polymer that contains silicon.

Alternatively, the first resist layer320may be formed of an organic-inorganic polymer, and the second resist layer340may be formed of an acrylate group polymer or a urethane group polymer.

An imprint process may be performed by moving another imprint stamp350above the second resist layer340. The implant stamp350may include a second pattern352on a lower surface thereof. The second pattern352may include a convex unit352aand a concave unit352b. The convex unit352aof the second pattern352may be formed to correspond to a convex unit322aof the first resist pattern322. The convex unit352aof the second pattern352may have a width W3greater than a width W4of the convex unit322aof the first resist pattern322. The convex unit352aof the second pattern352of the imprint stamp350may be aligned above the convex unit322aof the first resist pattern322.

Referring toFIG. 3E, the imprint stamp350may be pressed onto the second resist layer340until the convex unit352aof the second pattern352contacts an upper surface of the convex unit322aof the first resist pattern322. Next, an implant process described above is performed.

Referring toFIG. 3F, the imprint stamp350may be separated from the stamp substrate310. An upper surface of the first resist pattern322may be exposed. The exposed first resist pattern322may be removed by selectively etching the first resist pattern322. As a result, a second resist pattern342formed of the second resist layer340may remain on the stamp substrate310. The second resist pattern342may have a three-dimensional shape.

Referring toFIG. 3G, the second resist pattern342may be transferred onto the stamp substrate310when the second resist pattern342and the stamp substrate310are etched at a rate from above the second resist pattern342. In example embodiments, the rate may or may not be predetermined. A resultant pattern having a three-dimensional shape on the stamp substrate310may have a contracted or expanded dimension to the second resist pattern342in a vertical direction with respect to the stamp substrate310according to the etch rate of the second resist layer340and the stamp substrate310.

According to example embodiments, after primarily forming a three dimensional pattern on a stamp substrate sequentially using two imprint stamps having patterns different from each other, the shape of the three-dimensional pattern may be transferred onto the stamp substrate by etching an entire surface of the three-dimensional pattern. In this way, a nanoimprint stamp on which a complicated nano-scale pattern is formed can be readily formed by using the transferring method described above.

While the present invention has been particularly shown and described with reference to example embodiments, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims.