JP2011199136A - Mold for imprint, method of fabricating the same, and pattern transferred body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pattern forming method, a mold for imprint, and a pattern formed body which are suitable for formation of a fine pattern.SOLUTION: The fine pattern 27 is suitably formed on a base 21 by forming a pattern transferred body 20 having a wall-shaped projection 26 (fine projection) using the mold 16 for imprint having a microtrench 18 at a corner part of a pattern 17, and etching the base 21 using the pattern transferred body 20 having the wall-shaped projection 26 as an etching mask.

Description

  The present invention relates to an imprint mold suitable for forming a fine pattern, a method for producing the same, and a pattern transfer body manufactured using the imprint mold.

  A method of optically transferring a pattern is used to form a fine pattern in a semiconductor device manufacturing process or the like. For example, a photomask in which a pattern made of an opaque material such as chrome is formed on a transparent substrate such as glass is manufactured and placed directly or indirectly on a semiconductor substrate coated with a photosensitive resin. A photomask pattern is transferred onto a substrate by selectively exposing a resin in a light transmitting portion by irradiating light. This technique is generally called a photolithography method.

  However, since such a pattern formation method largely depends on the wavelength of light to be exposed, the size and shape of the pattern to be formed can be faithfully transferred onto a semiconductor substrate, particularly in the transfer of a fine pattern. It has become difficult.

  In addition, there is a problem that the optical contrast is reduced due to the diffraction phenomenon of light and the apparatus is expensive because it requires a complicated mechanism.

  These problems apply not only to the manufacture of semiconductor devices, but also to various pattern formations using photolithography methods such as displays, recording media, biochips, and optical devices.

  Other methods for forming fine patterns include electron beam lithography and focused ion beam lithography. However, there are problems with poor throughput and expensive equipment.

  Therefore, in recent years, a technique called an imprint method has been proposed that can transfer a fine pattern more faithfully than the conventional method (Non-Patent Document 1). As typical imprint methods, there are mainly a thermal imprint method and an optical imprint method.

Hereinafter, an example of the thermal imprint method will be described with reference to FIG.
First, a mold 210 made of metal or the like having an uneven shape is produced (FIG. 6A).
Next, a thermoplastic resin such as PMMA (polymethyl methacrylate, glass transition temperature 105 ° C.) is applied on the substrate 211 on which a pattern is to be formed to form a resin layer 212 (FIG. 6B).
Next, the base material 211 on which the resin layer 212 is formed is heated to a temperature higher than the glass transition point of the resin to soften the resin layer 212.
Next, the mold 210 and the base material 211 are brought into contact with each other and pressed so that the uneven surface side of the mold 210 faces the surface of the base material 211 on which the resin layer 212 is applied (FIG. 6C).
Next, the substrate temperature is lowered to the glass transition point or lower while being pressurized, the resin layer 212 is cured, and the mold 210 is peeled off.
As described above, the resin pattern 213 corresponding to the concavo-convex pattern of the mold 210 is formed on the resin layer on the base material 211 (FIG. 6D).
At this time, a portion corresponding to the convex portion of the mold 210 remains as a thin residual film 214 on the base material 211. Therefore, the residual film resin 214 is removed by O ₂ RIE (oxygen reactive ion etching) or the like, and the surface of the base material 211 is exposed (FIG. 6E).
Next, the substrate 211 is etched using the resin pattern 213 as a mask to produce a substrate 215 having a pattern 218 to which the resin pattern 213 is transferred (FIG. 6F), or Al or the like is lifted off. Or use for wiring.

Next, an example of the optical imprint method will be described with reference to FIG. 7 (see Patent Document 1).
First, a mold 220 made of a light-transmitting material such as quartz and having a concavo-convex shape on the surface is produced (FIG. 7A).
Next, a low-viscosity liquid photocurable resin is applied on the base 221 to form the resin layer 222 (FIG. 7B), and the uneven surface of the mold 220 is brought into contact with the resin layer 222 (FIG. 7). 7 (c)).
Next, light is irradiated from the back surface of the mold 220 in a state where the resin layer 222 on the substrate 221 and the mold 220 are in contact with each other, the photocurable resin 222 is cured, and the mold 220 is peeled off.
As described above, the resin pattern 223 corresponding to the concave / convex pattern of the mold 220 is formed on the resin layer on the substrate 221 (FIG. 7D).
At this time, a portion corresponding to the convex portion of the mold 220 remains as a thin residual film 224 on the base material 221. Therefore, the residual film resin 224 is removed by the O ₂ RIE method or the like to expose the surface of the base material 221 (FIG. 7E).
Next, the base material 221 is etched using the resin pattern 223 as a mask to produce a base material 225 having a pattern 228 to which the resin pattern 223 is transferred (FIG. 7F), or by lifting off Al or the like. Or use for wiring.

In the above-described thermal imprint method and optical imprint method, the remaining resin patterns 213 and 223 are also damaged when the remaining film is removed by the O ₂ RIE method (FIGS. 6E and 7E). . At this time, since the etching proceeds faster at the shoulder portions of the resin patterns 213 and 223 than at the flat portion, not only the film thickness of the resin patterns 213 and 223 decreases, but also the rectangularity of the resin patterns 213 and 223 is impaired. Thus, the deformed resin patterns 217 and 227 are obtained (FIG. 4A).

  Further, when etching the base materials 211 and 221 using the resin patterns 213 and 223 as masks (FIGS. 6F and 7F), the shoulder portions of the resin patterns 213 and 223 are etched faster than the flat portions. Therefore, not only the film thickness of the resin patterns 213 and 223 is reduced, but also the rectangularity of the resin patterns 213 and 223 is lost, resulting in deformed resin patterns 217 and 227 (FIG. 4B).

  When the base materials 211 and 221 are etched using the deformed resin patterns 217 and 227 as etching masks due to the deterioration of the rectangularity, the shapes of the patterns 218 and 228 formed on the base materials 211 and 221 are deteriorated and the dimensions are reduced. The accuracy may decrease (FIG. 4C).

  Thus, even if the film thickness of the resin patterns 213 and 223 is reduced or the rectangularity is impaired, if the height of the resin patterns 213 and 223 is increased, the pattern formed on the base materials 211 and 221. Deterioration of the shape of 218 and 228 and deterioration of dimensional accuracy can be reduced (FIG. 5A).

  However, in order to increase the height of the resin patterns 213 and 223, the height of the concavo-convex pattern formed on the molds 210 and 220 used for forming the resin patterns 213 and 223 must be increased. When the height is increased without changing the width of the concave / convex pattern formed on the molds 210 and 220, the aspect ratio of the concave / convex pattern is increased, and the concave / convex pattern having a high aspect ratio is transferred to the resin layers 212 and 222 using the imprint method. Then, the resin is not sufficiently filled in the uneven pattern of the molds 210 and 220 at the time of transfer, and the resin patterns 213 and 223 are deformed (FIG. 5B). When peeling from 222, the resin patterns 213 and 223 are destroyed (FIG. 5C), and transfer defects are likely to occur.

JP 2000-194142 A

Appl. Phys. Lett. , Vol. 67, p. 3314 (1995)

  The present invention has been made to solve the problems of the pattern forming method as described above, and uses an imprint mold suitable for forming a fine pattern, a method for producing the same, and an imprint mold. It aims at providing the pattern transfer object manufactured.

  The invention according to claim 1 of the present invention is an imprint mold provided with a concave pattern used for pattern formation by an imprint method, and has a concave micro-trench at a corner of the concave pattern. It is the mold for imprint characterized.

  The invention according to claim 2 of the present invention is the method for producing an imprint mold according to claim 1, wherein a hard mask layer is formed on a substrate, the hard mask layer is patterned, and the imprint mold is used. Predetermined conditions for forming a wall-shaped protrusion corresponding to the concave micro-trench at the corner of the concave pattern of the imprint mold at the tip corner of the convex pattern corresponding to the concave pattern of the mold And performing anisotropic etching on the substrate using the patterned hard mask layer as an etching mask, and removing the patterned hard mask layer from the substrate subjected to the anisotropic etching. This is a method for producing an imprint mold.

  The invention according to claim 3 of the present invention is the fabrication of an imprint mold according to claim 2, wherein the substrate is a quartz substrate, and the hard mask layer is a layer made of Cr. Is the method.

  The invention according to claim 4 of the present invention is a pattern transfer body in which the pattern of the imprint mold is transferred by pattern transfer using the imprint mold, and is formed on the base material and the base material. The imprint mold includes a transfer layer to which pattern transfer using the imprint mold according to claim 1 is performed, and the transfer target layer corresponds to the concave pattern of the imprint mold. A pattern in which a convex pattern and a wall-like protrusion located at the tip corner of the convex pattern corresponding to the concave micro-trench at the corner of the concave pattern are formed. It is a transcript.

  The invention according to claim 5 of the present invention is a pattern forming body transferred using the pattern transfer body imprint mold according to claim 4, wherein the convex pattern and the wall-shaped protrusion are formed. The transferred layer is a pattern transfer body that is used as an etching mask in anisotropic etching of the substrate.

  ADVANTAGE OF THE INVENTION According to this invention, the imprint mold suitable for formation of a fine pattern, its manufacturing method, and the pattern transfer body manufactured using the imprint mold can be provided.

It is a schematic sectional drawing which shows an example of the mold production method for imprint which concerns on the Example of this invention. It is a schematic sectional drawing which shows an example of the pattern formation method using the mold for imprint which concerns on the Example of this invention. It is a schematic sectional drawing which shows the effect of the pattern formation method which concerns on embodiment of this invention. It is a schematic sectional drawing which shows the problem in the conventional pattern formation method. It is a schematic sectional drawing which shows the problem in the conventional pattern formation method. It is sectional process drawing which shows the pattern formation method by a thermal imprint method. It is sectional process drawing which shows the pattern formation method by the optical imprint method.

  Hereinafter, the present invention will be described with reference to the drawings.

  First, a method for producing an imprint mold according to an embodiment of the present invention will be described.

  As shown in FIG. 1A, a hard mask layer 12 is formed on the substrate 11. As a method for forming the hard mask layer 12, a known thin film forming technique may be used as appropriate according to the material selected for the hard mask layer 12. For example, a sputtering method or the like may be used.

  The substrate 11 may be appropriately selected according to the application. For example, a silicon substrate, a quartz substrate, a sapphire substrate, an SOI substrate, or the like may be preferably used.

  The hard mask layer 12 may be a material having a high etching selectivity with respect to the selected substrate 11 in the step of performing anisotropic etching described later.

  Here, for example, when a quartz substrate is used as the substrate 11, it is preferable to use a layer made of Cr (chromium) for the hard mask layer 12.

  The quartz substrate is transmissive to general exposure light, and the pattern forming method according to the embodiment of the present invention is particularly used for manufacturing an imprint mold or a photomask used in the optical imprint method. It is suitable when using.

  By using a layer made of Cr for the hard mask layer 12, the etching selectivity of the hard mask layer 12 to the substrate 11 is increased under general etching conditions in the patterning process of the hard mask layer 12 described later. Can be set.

  Next, the hard mask layer 12 is patterned. As a method for patterning the hard mask layer 12, lithography using a resist film is used. For example, the hard mask layer 12 is patterned by forming a resist film 13 on the hard mask layer 12 (FIG. 1A). Next, the resist film 13 is patterned to form a resist pattern 14 (FIG. 1B). Next, by etching using the resist pattern 14 as an etching mask, the hard mask layer 12 is patterned to form a pattern 15 of the hard mask layer 12 (FIG. 1C). After patterning the hard mask layer 12, the resist pattern 14 is washed and peeled off.

  Next, anisotropic etching is performed on the substrate 11 from the side on which the pattern 15 of the hard mask layer 12 is formed on the substrate 11 (FIG. 1D). As the etching, a known etching method may be used as appropriate, and for example, dry etching, wet etching, or the like may be used.

  At this time, a micro-trench (small concave portion) 18 (corresponding to the concave micro-trench in the claim) is formed at the corner corner of the bottom of the concave pattern 17 (corresponding to the concave pattern in the claims) formed on the substrate 11. Etching is performed under the conditions for forming. The etching conditions may be adjusted as appropriate according to the hard mask layer 12 and the substrate 11 used as long as the micro-trench 18 is formed at the corners of the pattern 17. Specifically, for example, the etching conditions described later in the example column can be employed.

  Next, the imprint mold 16 (corresponding to the imprint mold in the claims) is produced by cleaning and peeling the pattern 15 of the hard mask layer 12 (FIG. 1 (e)).

  In order to improve releasability, surface treatment for improving releasability may be performed on the surface of the imprint mold 16 on which the pattern 17 is formed. For example, fluoropolymer processing or plasma processing may be performed.

Next, a method for producing a pattern transfer body according to an embodiment of the present invention will be described.
When the imprint mold 16 is produced, the pattern 17 formed on the imprint mold 16 is transferred to the transferred resin layer 22 on the substrate 21 by the thermal imprint method or the optical imprint method (the transferred layer in claims). (Corresponding to FIG. 2 (a) to (d)). Thereby, the pattern transfer body 20 having the resin pattern 23 shown in FIG. 2D or 2E (corresponding to the convex pattern in the claims) is obtained. The base material 21 may be appropriately selected according to the application. As the base material 21, for example, a silicon wafer can be suitably used. As the transferred resin layer 22, a resin having a high etching selectivity in a process of etching the base material 21 to be described later may be appropriately selected according to the selected imprint method. For example, when quartz is selected as the substrate 11 for producing the imprint mold 16, it is preferable to use a layer made of an ultraviolet curable resin as the transferred resin layer 22.

Next, the remaining resin film 24 remaining on the substrate 21 is removed (FIG. 2E). For removing the residual film, a known method may be used as appropriate, and for example, an O ₂ RIE method may be used. Moreover, the conditions for removing the residual film may be adjusted as appropriate according to the resin used.

At this time, since a minute protrusion 26 (corresponding to a wall-shaped protrusion in the claims) corresponding to the micro-trench 18 formed in the imprint mold 16 is formed at the corner of the tip of the resin pattern 23, the resin pattern The damage that 23 takes by the O ₂ RIE method can be reduced. For this reason, as shown to Fig.3 (a), the resin pattern 23 can be formed on the base material 21, without impairing rectangularity.

  Next, anisotropic etching is performed on the base material 21 using the resin pattern 23 as an etching mask (FIG. 2F). As the etching, a known etching method may be used as appropriate, and for example, dry etching may be used. Etching conditions may be adjusted as appropriate according to the resin and substrate used.

  At this time, since the micro projections 26 corresponding to the micro trenches 18 formed on the imprint mold 16 are formed at the corners of the tip of the resin pattern 23, damage to the resin pattern 23 due to etching can be reduced. . For this reason, as shown in FIG.3 (b), the pattern 27 can be formed in the base material 21 with sufficient precision.

  Hereinafter, a pattern forming method according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2 with an example in which pattern formation is performed using an optical imprint method. The pattern forming method of the embodiment of the present invention is not limited to the following embodiment.

  First, a quartz substrate was used as the substrate 11. A Cr layer having a Cr film thickness of 30 nm is formed as a hard mask layer 12 on a quartz substrate, and a positive resist FEP-171 (manufactured by FUJIFILM Electronics Materials) is coated with a thickness of 200 nm on the Cr layer. (FIG. 1 (a)).

Next, after irradiating the resist film 13 with an electron beam at a dose of 10 μC / cm ² with an electron beam drawing apparatus, development processing using a developer, rinsing, and drying of the rinse liquid are performed, and the resist pattern 14 (FIG. 1B) was obtained. Here, a TMAH aqueous solution was used as a developing solution, and pure water was used as a rinsing solution.

Next, the Cr layer was etched by dry etching using an ICP dry etching apparatus to obtain a Cr pattern 15 (FIG. 1C). At this time, the etching conditions for the Cr layer were Cl ₂ flow rate 40 sccm, O ₂ flow rate 10 sccm, He flow rate 80 sccm, pressure 30 Pa, ICP power 300 W, and RIE power 30 W.

Next, the quartz substrate was etched by dry etching using an ICP dry etching apparatus (FIG. 1D). At this time, the etching conditions for the quartz substrate were a C ₄ F ₈ flow rate of 20 sccm, an O ₂ flow rate of 10 sccm, an Ar flow rate of 75 sccm, a pressure of 5 Pa, an ICP power of 120 W, and an RIE power of 50 W.

  Next, the remaining Cr layer was subjected to wet peeling cleaning (FIG. 1 (e)).

  From the above, it was possible to produce a quartz mold 16 for optical imprinting in which micro trenches were formed in the pattern recesses.

  Next, using the quartz mold 16, the resin on the base material was subjected to photoimprinting, and the base material was patterned.

  First, a silicon wafer was used as the base material 21. An ultraviolet curable resin PAK-01 (Toyo Gosei Kogyo Co., Ltd.) was spin-coated on a silicon wafer to form a transfer resin layer 22 (FIG. 2B).

  Next, the quartz mold 16 was brought into contact with the transferred resin layer 22 on the silicon wafer so that the surface on which the pattern of the mold 16 was formed was opposed (FIG. 2C).

Next, exposure of 20 mJ / cm ² was performed from the back side of the quartz mold 16 using a high-pressure mercury lamp as a light source.

  Next, the silicon wafer and the quartz mold 16 were peeled off to obtain a resin pattern 23 on the silicon wafer, thereby producing a pattern transfer body 20 (FIG. 2 (d)). At this time, a minute protrusion 26 corresponding to the micro trench formed in the quartz mold 16 was formed on the resin pattern. The remaining film thickness was 80 nm.

Next, the remaining film 24 was removed by O ₂ plasma ashing (FIG. 2E). At this time, the O ₂ plasma ashing conditions were an O ₂ flow rate of 50 sccm, a pressure of 30 Pa, and an RF power of 100 W.

At this time, when the remaining film 24 was removed by O ₂ plasma ashing, the heights of the resin pattern 23 and the minute protrusions 26 were reduced, but the minute protrusions 26 remained on the resin pattern 23. As described above, the pattern transfer body 20 having the resin pattern 23 provided with the fine protrusions 26 can be formed on the silicon wafer.

Next, the silicon wafer was etched using the resin pattern 23 as an etching mask (FIG. 2F). At this time, the etching conditions of the silicon wafer were CF ₄ flow rate 30 sccm, C ₄ F ₈ flow rate 20 sccm, pressure 30 Pa, ICP power 500 W, and RIE power 50 W.

  At this time, when the silicon wafer was etched, the minute protrusions 26 disappeared and the height of the resin pattern 23 decreased, but the rectangularity of the resin pattern 23 was sufficiently maintained. Therefore, a pattern 27 having a high dimensional accuracy and a rectangular cross-sectional shape could be formed on the silicon wafer.

Next, the resin was peeled off by O ₂ plasma ashing (conditions: O ₂ flow rate 50 sccm, pressure 30 Pa, RF power 100 W).

  From the above, it was possible to obtain the silicon wafer 25 on which the pattern 27 having a high dimensional accuracy and a rectangular cross-sectional shape was formed.

  The pattern forming method of the present invention is expected to be used in a wide range of fields where a fine pattern is required. For example, an imprint mold, a semiconductor device, an optical element, a wiring circuit (such as a dialer machine structure wiring), a recording device (such as a hard disk or a DVD), a medical test chip (such as a DNA analysis application), a display, etc. (Diffusion plate, light guide plate, etc.), expected to be used for micro-channels.

210 ... Mold 211 ... Base 212 ... Resin layer 213 ... Resin pattern 214 ... Residual film 215 ... Patterned base 217 ... Deformed resin pattern 218 ... Pattern 220 ... Mold 221 ... Base 222 ... Resin layer 223 ... Resin pattern 224 ... Residual film 225 ... Base material 227 having pattern ... Deformed resin pattern 228 ... Pattern 11 ... Substrate 12 ... Hard mask layer 13 ... Resist film 14 ... Resist pattern 15 ... Hard mask layer pattern 16 ... Imprint mold 17 ... Substrate pattern 18 ... Imprint mold micro-trench 20 ... Pattern transfer body 21 ... Base material 22 ... Resin layer 23 ... Resin pattern 24 ... Residual film 25 ... Silicon wafer 26 with rectangular pattern formed ... Micro projection 27 ... Pattern

Claims (5)

  An imprint mold having a concave pattern used for pattern formation by an imprint method, wherein a concave microtrench is provided at a corner of the concave pattern. A method for producing an imprint mold according to claim 1,
Forming a hard mask layer on the substrate,
Patterning the hard mask layer;
Wall-shaped projections corresponding to the concave micro-trench at the corners of the concave pattern of the imprint mold are formed at the corners of the convex pattern corresponding to the concave pattern of the imprint mold. An anisotropic etching is performed on the substrate using the patterned hard mask layer as an etching mask under predetermined conditions.
Removing the patterned hard mask layer from the anisotropically etched substrate;
A method for producing an imprint mold characterized by the above.   The method for producing an imprint mold according to claim 2, wherein the substrate is a quartz substrate, and the hard mask layer is a layer made of Cr. A pattern transfer body to which a pattern of the imprint mold is transferred by pattern transfer using an imprint mold,
A substrate;
A transfer layer formed on the base material and subjected to pattern transfer using the imprint mold according to claim 1 as the imprint mold;
In the transferred layer, a convex pattern corresponding to the concave pattern of the imprint mold and a concave micro-trench in the corner corner of the concave pattern are formed at the tip corner of the convex pattern. A wall-shaped protrusion is formed,
A pattern transfer body characterized by that.   The pattern transfer body according to claim 4, wherein the transferred layer on which the convex pattern and the wall-shaped protrusion are formed is used as an etching mask in anisotropic etching of the substrate.

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