JP2005159358A - Nano imprint lithographing method and substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To decrease a problem of a mold fixing with a substrate during imprint. <P>SOLUTION: An improved method for nano imprint, more concretely, of providing a nano scale pattern on the substrate is disclosed. According to this improvement, a mold (100) and a substrate (115) are provided, and before a pattern has been imprinted from the mold (100) to the substrate (115) by pressing the mold (100) and the substrate (115) each other, a plurality of coating layer (120, 125, 130) are formed on the substrate (115). The top layer having pure anti-adhesion function is provided on the above-mentioned substrate. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates generally to the field of nanoimprint lithography, and more specifically to a method and means for generating a nanoscale pattern on a substrate.

  Quantum devices whose performance is affected by materials incorporated in nanometer scale, eg single-electron devices, promise the upcoming electron generation. Advances in nano-manufacturing technology are essential for the manufacture of such nanodevices. Indeed, extreme electron beam lithography, such as the AFM (Atomic Microscope) based method of handling nanoparticles, has made it possible to produce structures and patterns with dimensions below a few nanometers. However, these techniques worked in series, which prevented these nanolithography from being applied to mass production of devices. Nanoimprint lithography (NIL) has natural potential as a promising candidate for manufacturing such nanodevices in parallel. Here, stamps patterned by serial lithographic techniques, mostly electron beam lithography, can be used as replicas in stamp printing techniques, much like the compact disc (CD) manufacturing process. The CD manufacturing technique was introduced in 1975 and demonstrated its excellent mass production capacity. The overall yield of CD production (in the worst case) exceeded 67% in the entire area of each 6 inch compact disc being produced.

  Nanoimprint lithography (NIL) is a known technique for producing nanoscale patterns on a substrate. This substrate can be formed of a semiconductor material, such as silicon, indium phosphide or gallium arsenide, and is used, for example, in the manufacture of semiconductor components. The substrate can also be formed of other materials, such as ceramic materials, metals, or polymers with relatively high glass transition temperatures for other applications such as biosensors.

  The trend in microelectronics is towards smaller dimensions. In principle, it has been developed so that the size is reduced to half of its size about every three years. For example, commercial parts are now manufactured with a structure of about 130 nm in size, but there is a need for smaller dimensions.

  The basic principle of NIL is, for example, mechanical deformation of a thin film layer coated on a flat surface of silicon. The NIL process can be compared to the CD manufacturing process and can be described in the following three stages.

  1. Manufacture of molds (ie, mold templates): Molds can be manufactured from a variety of materials, such as metals, semiconductors, ceramics, or certain plastics. In order to form a three-dimensional structure on one surface of the mold, various lithography methods can be used depending on the size of the structure and the specifications for its resolution. Electron beam and x-ray lithography are typically used for structure dimensions below 300 nm. Direct laser exposure and UV lithography are used for larger structures.

  2. Imprint: A thin film layer of polymer, for example polyimide, is attached to a flat substrate of silicon. This layer is heated to a predetermined temperature, the so-called imprint temperature. The mold and the substrate are pressed together so that the opposite structure of the mold is transferred to the polymer layer of the substrate.

  During the imprint procedure, the resist is heated to a temperature above its glass transition temperature. At that temperature, the (thermoplastic) resist becomes a viscous liquid that can flow out and can therefore be easily transformed into the shape of the mold. The resist viscosity decreases with increasing temperature.

  3. Structural transfer: A thin layer of polymer remains in the areas of the polymer layer that are crimped together. The last step is removal of this thin residual layer on the substrate. This removal can be performed in a so-called “RIB”, or in an oxygen plasma, or in an anisotropic etching process, such as a reactive ion etching RIE. The thinner this remaining layer, the more precise the structure that can be formed using nanoimprint.

  A problem with the conventional NIL procedure is that the mold may stick to the thin film layer during crimping, thereby reducing the accuracy of the reverse pattern transferred into the thin film layer. Therefore, in order to avoid such sticking, the mold is usually provided with an anti-sticking layer.

  Non-Patent Document 1 describes a polymer imprint resist layer integrated with an anti-adhesive material in a polymer.

Another imprint method uses imprint combined with UV exposure to cure the polymer. This alternative approach to lithography is based on a two-layer imprint strategy. In this process, a standard quartz mask having a patterned chrome surface is etched by reactive ion etching to form a high resolution relief image on the surface. The remaining chromium in the fluorinated self-assembled monolayer is removed and the template is surface treated. A low viscosity photopolymerizable stylization is introduced in the gap between the two faces. The template is then brought into contact with the surface. This solution is called an etch barrier and is photopolymerized by exposure through the back side of the quartz template. The template is separated from the substrate, leaving a UV-cured replica of the relief structure on the substrate. By using this imprint process, features that are less than 40 nm in size have been reliably produced. The problem / disadvantage of this technique is that for larger area imprints where the polymer must be applied prior to each imprint procedure, it is not suitable without stepping and stamping / flushing.
"Step and Flash Imprint Lithography: A New Approach to High-Resolution Patterning", Proc. SPIE Vol. 3676, 379-389 (1999) by Willson et al.

  There are several issues worth working on in relation to imprint lithography. One critical region is to perform the next processing level while leaving the same resolution as demonstrated in the polymer layer. Forming a patterned metal layer is one application. The metal layer patterned with high definition is used as a wiring in an integrated circuit. These metal layers can also be used as catalysts for subsequent layer growth. Additional approaches such as lift-off are desirable when subsequent metal layers cannot be easily etched, for example due to the etching rate depending on the crystal orientation. However, there is a problem with a single polymer layer when transferring the pattern via metal lift-off. Non-vertical sidewalls resulting from the imprint process result in tearing and peeling of the metal film during lift-off. If the imprint member does not have vertical sidewalls, non-vertical sidewalls occur in imprint lithography. Even if the imprint member has vertical sidewalls, the imprinted membrane is due to the descumming step essential to remove residual polymer from the bottom of the imprinted feature. A non-vertical side wall is formed. Accordingly, there is a need for a technique that minimizes the problems associated with metal lift-up using a single layer of resist.

  The above-described imprint technique has another problem targeted by the present invention, for example, a problem that the surface adhesive property changes when the substrate and the organic material change. This limits the polymer material of the process in combination with certain substrate materials such as silicon, nickel, quartz, glass, silicon nitride and the like. Using a release material that contacts the mold is not very safe to ensure that the process can be used in industrial production.

  Accordingly, a nanoimprint lithography method that allows for transfer of finer nanoscale structures from a mold to a substrate in an economical manner and eliminates / reduces problems associated with the mold sticking to the substrate during imprinting and There is a need to find a means.

  The object of the present invention is to eliminate / reduce the above-mentioned drawbacks / problems.

  That is, it is an object of the present invention to discover nanoimprint lithography methods and means that allow for transfer of finer nanoscale structures from a mold to a substrate in an economical manner.

  Another object of the present invention is to discover nanoimprint lithography methods and means that reduce the problems associated with the mold sticking to the substrate during imprinting.

  Yet another object of the present invention is to discover nanoimprint lithography methods and means for improving the accuracy of imprint patterns on a substrate.

  It is a further object of the present invention to provide nanoimprint lithography methods and means that improve imprint quality and release of the polymer from the substrate by reducing polymer sticking to the mold surface.

  A still further object of the present invention is to provide a method and means for nanoimprint lithography that allows for economical mass production of more accurate nanostructures.

  According to one aspect of the present invention, the present invention is a method of forming a structured pattern on a substrate, wherein the substrate is covered with a plurality of coating layers before crimping, and each coating layer has a specific function. The above object is achieved by a method comprising

  According to another aspect of the present invention, the present invention provides a method for forming a structured pattern on a substrate, wherein the topmost coating layer on the top surface of the substrate has a pure anti-sticking function. To achieve the above object.

  According to still another aspect of the present invention, there is provided a substrate for forming a nanoscale pattern thereon, which is covered with a plurality of coating layers each having a specific function.

  According to yet another aspect of the present invention, a substrate according to the present invention has a top layer coating that has a purely anti-sticking function.

  While the invention has been summarized as described above, the invention is defined by the independent claims 1 and 8. Further embodiments of the invention are defined by the dependent claims 2 to 7, 9 and 10.

  By using the imprint technique according to the present invention, the imprint result shows a higher quality that the polymer does not actually adhere to the surface of the mold and the polymer does not peel from the substrate. Furthermore, the imprint results show that the above-mentioned problems with non-vertical sidewalls have been reduced. Accordingly, a nano-pattern imprint method is disclosed that provides higher accuracy and can more uniformly and economically produce finer structures on a substrate.

  For example, as described in Non-Patent Document 1 above, a polymer imprint resist layer having an anti-stick material incorporated into a polymer is described, the present invention relates to a polymer imprint resist layer on a substrate during nanoimprint lithography. It is based on the recognition of problems / disadvantages associated with incorporating anti-stick materials. The above approach far departs from the optimal anti-stick performance and causes the polymer to stick to the mold, thus preventing the economical mass production of finer nanoscale patterns on the substrate.

  The present invention is shown in FIG. The mold 100 has a recess 105 and a protrusion 110 for forming a nanostructure pattern. The protrusion has a height of about 150 nm. As is known in the art, the mold 100 can be made from any suitable material, such as glass, silicon, or a metal such as nickel. According to a more preferred embodiment, the mold is covered with a thin anti-adhesion layer 190 (also referred to as an anti-adhesion layer) in the form of a monolayer similar to Teflon. The thickness of layer 190 is about 10 nm or less and can be obtained by chemical vapor reaction on a stamp as is known by those skilled in the art. As known to those skilled in the art, a substrate 115 is provided that is formed from any suitable material, such as glass (or silicon glass). The substrate 115 is covered with a thin fixing layer 120 (also referred to as an adhesive layer) made of 3-methacryl-oxypropyl-dimethyl-chlorosilane, hexamethyl-disilane, or HMDS. Is called. Layer 120 is preferably about 10 nm or less and can be obtained, for example, by spin coating. Next, a formation layer (also referred to as an imprint resist layer) 125 is provided on the top surface of the layer 120. This layer 125 can be composed of, for example, PMMA (PolyMethyl-Methacrylic Acid), preferably It has a thickness of about 150 nm. The imprint PMMA layer 125 can be provided using any suitable known technique such as spin coating. In accordance with the present invention, the anti-adhesion layer 130 can be composed of, for example, tridecafluro- (1H, 1H, 2H, 2H) tetrahydrooctylamine or similar partially or fully fluorinated compounds. . The anti-stick layer 130 preferably has a thickness of 10 nm or less, and can be spin-coated, for example, on the imprinted PMMA polymer layer 125 as realized by those skilled in the art.

  Referring to FIG. 2, a flowchart for a nanoimprint method according to the present invention is shown. In step 200, a mold 100 and a substrate 115 are prepared according to the description given above with reference to FIG. Next, in step 210, the substrate 115 having the three layers 120, 125, and 130 and the mold 100 are heated above the glass transition temperature, thereby softening the layer 125. In step 220, according to the so-called soft imprinting method, by pressing the mold onto the coating layer 120, 125, 130 of the substrate using a pressure of about 5 to 100 bar, preferably about 30-60 bar in less than 300 seconds. Execute pattern transfer. This soft imprint method uses a pressure control chamber with a flexible thin film that forms a counterstay for the substrate / mold in order to force the substrate and the mold to be evenly distributed with the force distributed between them. It is what you use. A soft imprint method is disclosed in WO 01/42858. Thereafter, the formation layer 125 is solidified by cooling and curing in step 225 by known methods. In step 230, the mold 100 is released from the substrate 115. Thus, a structured nanoscale pattern is provided on the substrate by transferring the reverse pattern on the mold.

  The present invention overcomes the problems and disadvantages associated with known techniques, for example, by providing the substrate with an uppermost anti-stick layer on the top surface of the imprint resist layer. This facilitates even distribution of the anti-sticking layer and also makes the anti-sticking layer uniformity less critical in the accuracy and fineness of the final imprint result. The present invention provides a thin monolayer, eg, a monolayer similar to Teflon®, as an anti-stick layer on the mold. According to the present invention, the thickness of a monolayer similar to Teflon is about 10 nm or less, but this thickness may vary depending on the chemical reaction applied.

  The invention has been described with illustrative examples. The drawings do not limit the invention, but merely show the operating principle of the invention. For those skilled in the art, for example with regard to additional functional layers, such as the introduction of so-called lift-off layers between the substrate 115 and the anti-adhesion layer 130, etc., depart from the scope of the invention as defined in the claims of this application. Many changes can be made without doing so.

1 shows a substrate and a mold for forming a nanoscale pattern according to the present invention. Figure 2 shows a flowchart of a method for providing a nanoscale pattern on a substrate that can be used to carry out the present invention.

Explanation of symbols

100: Mold 105: Recess 110: Projection 115: Substrate 125: Formation layer (imprint resist layer)
130, 190: Anti-adhesion layer (anti-adhesion layer)

Claims (11)

The substrate (115) covered with a plurality of coating layers including the imprint resist layer (125) and the mold (100) are bonded to each other to transfer a reverse pattern from the mold to the substrate. A nanoimprint lithography method for providing a nanoscale pattern on the substrate,
Providing a top coating layer (130) having a pure anti-sticking function on the top surface of the substrate prior to pressing.   The method of claim 1, further comprising providing an anchoring layer (120) disposed under the imprint resist layer (125) prior to pressing.   The method of any preceding claim, further comprising forming the anti-stick layer (130) to include a partially fluorinated compound.   The method of any preceding claim, further comprising forming the anti-stick layer (130) to include a fully fluorinated compound.   The method of claim 1, further comprising the step of forming the anti-stick layer (130) to include triridecafluro- (1H, 1H, 2H, 2H) tetrahydrooctylamine.   The method of claim 1, further comprising providing an anti-adhesion layer (190) on the mold prior to pressing.   By utilizing a pressure control chamber having a flexible thin film on which the substrate and the mold are placed during transfer of the pattern to the substrate (115), between the substrate and the mold The method of claim 1, further comprising providing a substantially evenly distributed force. A substrate (115) that is covered by a plurality of coating layers including an imprint resist layer (125) and designed to form a nanoscale pattern thereon by nanoimprint lithography,
A substrate, characterized in that the uppermost coating layer (130) is formed on the top surface of the compound giving a pure anti-adhesion function.   The substrate of claim 8, wherein the anti-stick layer (130) comprises a partially fluorinated compound.   The substrate of claim 8, wherein the anti-stick layer (130) comprises a fully fluorinated compound.   9. The substrate of claim 8, wherein the anti-sticking layer (130) comprises tridecafluro- (1H, 1H, 2H, 2H) tetrahydrooctylamine.

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