Abstract:
A method of forming a pattern by using an imprint process includes: forming an adhesion promoting layer only in a pattern formation region on a substrate; coating a resin to cover the substrate and the adhesion promoting layer; transferring a pattern of a stamp mold to the resin covering the substrate and the adhesion promoting layer, by pressing the stamp mold onto the resin; irradiating ultraviolet light onto the resin covering the substrate and the adhesion promoting layer, to cure the resin and form a pattern of the cured resin to correspond to the pattern of the stamp mold, on the substrate; and detaching the stamp mold from the substrate, to leave a portion of the cured resin pattern only on the adhesion promoting layer on the substrate and to remove a remaining portion of the cured resin pattern from the substrate.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to Korean Patent Application No. 10-2014-0095014, filed on Jul. 25, 2014, and all the benefits accruing therefrom under 35 U.S.C. §119, the disclosure of which is incorporated herein in its entirety by reference. 
     BACKGROUND 
     1. Field 
     Provided are methods related to forming an aligned pattern in a pattern formation region, by using an imprint process. 
     2. Description of the Related Art 
     Nano imprint lithography is a nano/micro patterning technology that may replace photolithography and electron beam lithography. In a nano imprint process, when a resin curable by light of a specific wavelength is coated on a substrate and then is pressed by using a mold having an opposite shape to a pattern to be formed, a fluidic resin fills an empty space of the mold due to a capillary phenomenon. The resin is cured by light irradiation and then the mold is removed to form a pattern on the substrate. 
     In general, in a device fabricating process, a pattern formed by a nano imprint process may be used as a sacrificial layer in a subsequent process. For example, the pattern may be an etching mask. 
     SUMMARY 
     In order to use a pattern formed by a nano imprint process in an actual device during a fabricating process thereof, the pattern is formed only in a specific region of a substrate to allow a subsequent process during the device fabrication process to be performed. However, in an actual nano imprint process, since a portion of the pattern is formed outside the specific region of the substrate due to misalignment during mold contact, or since a burr is formed due to a relatively thick accumulation of a resin that leaks from a mold during pressing, performing a subsequent process within the device fabrication process is difficult. 
     Therefore, in order to perform a subsequent process within the device fabrication process smoothly and accurately, a nano imprint process whereby a uniform pattern may be formed in a specific region of a substrate is desired. 
     Provided are methods of forming an aligned pattern only in a specific region of a substrate without the occurrence of a burr, in a nano imprint process. 
     Additional features will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice thereof. 
     Provided is a method of forming an aligned pattern by using an imprint process, the method including: forming an adhesion promoting layer only in a pattern formation region on a first substrate; coating a resin on the first substrate to cover the adhesion promoting layer; transferring a first pattern of a stamp mold to the resin coated on the first substrate and covering the adhesion promoting layer, by pressing the stamp mold onto the resin coated on the first substrate and covering the adhesion promoting layer; irradiating ultraviolet light onto the resin coated on the first substrate and covering the adhesion promoting layer, to cure the resin and form a second pattern of the cured resin to correspond to the first pattern of the stamp mold, on the first substrate; and detaching the stamp mold from the first substrate, to leave a portion of the cured resin second pattern only on the adhesion promoting layer on the first substrate and to remove a remaining portion of the cured resin second pattern from the first substrate. 
     The forming the adhesion promoting layer may include: forming a mask on the first substrate to expose the pattern formation region; forming an adhesion promoting material layer on the mask to cover the mask and to cover the pattern formation region; and removing the mask from the first substrate to remove a portion of the adhesion promoting material layer formed in a region outside the pattern formation region. 
     The adhesion promoting material layer may include an ultraviolet-curable material. 
     The adhesion promoting material layer may include a solution including a silane coupling agent. 
     The adhesion promoting material layer may be formed in a dry state to have a thickness of about 10 nanometers (nm) or less. 
     The adhesion promoting layer may be formed by spin coating or vapor deposition. 
     The forming the mask may include attaching a mask material layer onto the first substrate by an electrostatic force or a reversible bonding. 
     The mask material layer may include a polymer film or a release film. 
     The forming the adhesion promoting layer may include: forming a mask on the first substrate to expose a surface of the substrate in the pattern formation region; and performing an oxygen plasma treatment or an ultraviolet ozone treatment on a surface of the first substrate exposed in the pattern formation region. 
     The curing of the resin may include chemically bonding the adhesion promoting layer and the resin to each other. 
     The method may further include: forming an adhesive layer on a second substrate separate from the first substrate; pressing the stamp mold including the remaining portion of the cured resin second pattern thereon, onto the second substrate including the adhesive layer thereon, such that the remaining portion of the cured resin second pattern on the stamp mold contacts the adhesive layer on the second substrate; and detaching the stamp mold from the second substrate to leave the remaining portion of the cured resin second pattern in contact with the adhesive layer on the second substrate and to remove the remaining portion of the cured resin second pattern from the stamp mold. 
     The adhesive layer may include a double-sided tape. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and/or other embodiments will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings in which: 
         FIGS. 1A to 1F  are cross-sectional views schematically illustrating a method of forming an aligned pattern in a pattern formation region by using an imprint process according to an embodiment; and 
         FIGS. 2A to 2C  are cross-sectional views schematically illustrating a method of removing a resin formed on a stamp mold according to an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to embodiments, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. In this regard, the embodiments may have different forms and should not be construed as being limited to the descriptions set forth herein. Accordingly, the embodiments are merely described below, by referring to the figures, to explain the invention. 
     Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. In the drawings, the thicknesses of layers and regions are exaggerated for clarity. The embodiments described below are merely exemplary, and various modifications may be made therein. 
     It will be understood that when a layer is referred to as being “on” another layer or substrate, it may be directly on the other layer or substrate, or one or more intervening layers may also be present. Throughout the specification, like reference numerals are used to denote like elements and redundant descriptions thereof will be omitted. 
     It will be understood that, although the terms “first,” “second,” “third” etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, “a first element,” “component,” “region,” “layer” or “section” discussed below could be termed a second element, component, region, layer or section without departing from the teachings herein. 
     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms, including “at least one,” unless the content clearly indicates otherwise. “Or” means “and/or.” As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. It will be further understood that the terms “comprises” and/or “comprising,” or “includes” and/or “including” when used in this specification, specify the presence of stated features, regions, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, regions, integers, steps, operations, elements, components, and/or groups thereof. 
     Furthermore, relative terms, such as “lower” or “bottom” and “upper” or “top,” may be used herein to describe one element&#39;s relationship to another element as illustrated in the Figures. It will be understood that relative terms are intended to encompass different orientations of the device in addition to the orientation depicted in the Figures. For example, if the device in one of the figures is turned over, elements described as being on the “lower” side of other elements would then be oriented on “upper” sides of the other elements. The exemplary term “lower,” can therefore, encompasses both an orientation of “lower” and “upper,” depending on the particular orientation of the figure. Similarly, if the device in one of the figures is turned over, elements described as “below” or “beneath” other elements would then be oriented “above” the other elements. The exemplary terms “below” or “beneath” can, therefore, encompass both an orientation of above and below. 
     “About” or “approximately” as used herein is inclusive of the stated value and means within an acceptable range of deviation for the particular value as determined by one of ordinary skill in the art, considering the measurement in question and the error associated with measurement of the particular quantity (i.e., the limitations of the measurement system). For example, “about” can mean within one or more standard deviations, or within ±30%, 20%, 10%, 5% of the stated value. 
     Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure, and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. 
     Exemplary embodiments are described herein with reference to cross section illustrations that are schematic illustrations of idealized embodiments. As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, embodiments described herein should not be construed as limited to the particular shapes of regions as illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. For example, a region illustrated or described as flat may, typically, have rough and/or nonlinear features. Moreover, sharp angles that are illustrated may be rounded. Thus, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the precise shape of a region and are not intended to limit the scope of the present claims. 
       FIGS. 1A to 1F  are cross-sectional views schematically illustrating a method of forming an aligned pattern in a pattern formation region by using an imprint process according to an embodiment. 
     Referring to  FIG. 1A , a first substrate  110  is prepared. The first substrate  110  may include glass or silicon. However, the invention is not limited thereto. In an embodiment, for example, the first substrate  110  may also include plastic or the like. 
     A mask  120  is formed on the first substrate  110 , in a region other than a pattern formation region A. That is, the mask  120  is formed to expose (e.g., not overlap) the pattern formation region A. The mask  120  may include a material that may be relatively easily attached to the first substrate  110  by an electrostatic force with respect to a material of the first substrate  110 . In an embodiment, for example, the mask  120  may include a plastic film such as a polyethylene terephthalate (“PET”) film. When the mask  120  includes the plastic film, the mask  120  may be relatively easily detached from the first substrate  110  in a subsequent process within the method of forming an aligned pattern. 
     The mask  120  may include a material that is reversibly bonded to the first substrate  110 . In an embodiment, for example, the mask  120  may include a release film. Polycarbonate (“PC”), polyethylene naphthalate (“PEN”), or the like may be used as the release film. 
     Also, the mask  120  may include a tape that may be attached to the first substrate  110 . 
     Referring to  FIG. 1B , to increase an adhesive force within the pattern formation region A, an adhesion promoting layer  130  is formed on the first substrate  110  to cover the first substrate  110  and to cover the mask  120 . The material for forming the adhesion promoting layer  130  may include an ultraviolet (“UV”)-curable material. In an embodiment, for example, the material for forming the adhesion promoting layer  130  may include a solution including a silane-based coupling agent. Ethanol or the like may be used as a solvent. 
     The silane-based coupling agent may include  T -glycidoxy propyl trimethoxysilane, mercapto propyl trimethoxysilane, methyl trimethoxysilane, or trialkoxysilane. 
     The material for forming the adhesion promoting layer  130  may be formed on the first substrate  110  by spin coating, drop dispensing or deposition. 
     The material for forming the adhesion promoting layer  130 , coated on the first substrate  110 , may be formed to cover not only the pattern formation region A exposed by the mask  120  but also a periphery of the pattern formation region A and/or a top surface of the first substrate  110 . 
     The material for forming the adhesion promoting layer  130  may be formed in a dry state to have a monolayer thickness. In an embodiment, for example, the material for forming the adhesion promoting layer  130  may be formed to a thickness of about 2 nanometers (nm) depending on a material thereof. Also, the material for forming the adhesion promoting layer  130  may be formed to a thickness of about 10 nm or less. When the material for forming the adhesion promoting layer  130  is formed to a thickness of more than about 10 nm, a portion of the material for forming the thickness of the adhesion promoting layer  130 , which is to be removed from the resulting structure described later, increases. The thickness may be defined in a direction normal to a surface upon which the adhesion promoting layer  130  is coated. 
     However, the invention is not limited to the above process of increasing an adhesive force within the pattern formation region A of the first substrate  110 . In an embodiment, for example, instead of coating a material for forming the adhesion promoting layer  130 , an oxygen plasma treatment and/or an UV ozone treatment may be performed on the pattern formation region A of the first substrate  110 , which is exposed by the mask  120 , to increase the adhesive force of the first substrate  110  with respect to the resin in the pattern formation region A. 
     To perform the oxygen plasma treatment on the pattern formation region A, the pattern formation region A, the first substrate  110  and layers thereon may be processed in a process chamber for performing the oxygen plasma treatment. A chamber pressure within the process chamber may be maintained at about 0.4 millibar (mbar), while about 100 watts (W) of power is used, and oxygen gas is supplied at about 5 standard cubic centimeters per minute (sccm) into the chamber. The oxygen plasma treatment is performed for about 60 seconds. 
     To perform the UV ozone treatment on the pattern formation region A, a UV lamp is used to irradiate a UV light with a wavelength of about 254 nm and an intensity of about 28,000 microwatts per square centimeter (μW/cm 2 ) for about 90 seconds, such as to the pattern formation region A, the first substrate  110  and layers thereon. Within a process chamber for performing the UV ozone treatment, the UV light reacts with oxygen in the process chamber, and thus, ozone and oxygen atoms providing relatively strong oxidation are generated. The oxygen atoms essentially clean a surface of the transfer substrate exposed at the pattern formation region A to increase the adhesive force thereof relative to other material layers. 
     Hereinafter, for convenience of explanation, a region modified by the oxygen plasma treatment or the UV ozone treatment may also be referred to as the adhesion promoting layer  130 . 
     Referring to  FIG. 1C , the mask  120  is removed from the first substrate  110 . In removing the mask  120  from the first substrate  110 , the adhesion promoting layer  130  disposed on the mask is detached from the first substrate  110  together with the mask  120 . A portion of the adhesion promoting layer  130  may remain on the pattern formation region A due to the adhesive force with the first substrate  110 . 
     When a film having an electrostatic force is used as the mask  120 , the mask  120  may be relatively easily detached from the first substrate  110 . 
     When a release film is used as the mask  120 , the mask  120  may be relatively easily separated from the first substrate  110  by applying heat thereto. 
     When a tape is used as the mask  120 , the adhesion promoting layer  130  on the tape may be removed by removing the tape. 
     Referring to  FIG. 1D , a UV-curable resin  140  is coated on the first substrate  110  to cover the adhesion promoting layer  130 . The UV-curable resin  140  may be, for example, an acryl-based resin, a polyimide-based resin, a polyamide-based resin, a novolac-based resin, a poly methyl methacrylate (“PMMA”) resin, a buthyl methacrylate (“BMA”) resin, an urethane acrylate resin, a poly vinyl alcohol resin, or the like. The adhesion promoting layer  130  covers the pattern formation region A. The adhesion promoting layer  130  may extend further than the pattern formation region A to overlap a portion of the first substrate  110  adjacent to the pattern formation region A. 
     Referring to  FIG. 1E , a stamp mold  150  is pressed onto the first substrate  110  with the UV-curable resin  140  thereon. The stamp mold  150  includes a first pattern  152  formed therein, and the first pattern  152  contacts the resin  140  on the first substrate  110  by the pressing of the stamp mold  150  onto the first substrate  110 . Thereafter, UV light is irradiated onto the UV-curable resin  140 . In this process, the UV-curable resin  140  may be chemically bonded to be relatively strongly bonded to the adhesion promoting layer  130  on the pattern formation region A of the first substrate  110 . That is, the coupling agent included in the adhesion promoting layer  130  may be chemically bonded to the UV-curable resin  140 . Thus, the adhesive force between the UV-curable resin  140  and the adhesion promoting layer  130  may be increased. 
     The stamp mold  150  may include quartz or UV-curable polymer, for example, polyurethane acrylate. 
     The UV-curable resin  140  may also be coated in a region outside the pattern formation region A on the first substrate  110 . Although not illustrated, a burr may be formed from the UV-curable resin  140  disposed outside the pattern formation region A. 
     The first pattern  152  is transferred to the UV-curable resin  140  to form a second pattern portion  142  and a third pattern portion  144  of the UV-curable resin  140 . The second pattern portion  142  and the third pattern portion  144  of the UV-curable resin  140  may have the same shape as each other and may be formed at different positions along the first substrate  110 . That is, the second pattern portion  142  is a patterned portion of the UV-curable resin  140  corresponding to the pattern formation region A, and the third pattern portion  144  is a patterned portion of the UV-curable resin  140  disposed corresponding to an area other than the second pattern portion  142 . 
     Referring to  FIG. 1F , the stamp mold  150  is separated from the first substrate  110 . In this process, the second pattern portion  142  on the adhesion promoting layer  130  remains on the first substrate  110  due to the adhesive force with the adhesion promoting layer  130 , and the third pattern portion  144  in a remaining region of the of the UV-curable resin  140  disposed on the first substrate  110  is separated from the first substrate  110 . Since the distance between convex portions  154  of the first pattern  152  is in range of nanometers or micrometers, the resin (e.g., the third pattern portion  144 ) filling a space defined between the convex portions  154  has a relatively large surface contact area with surfaces of the first pattern  152 . Thus, the bonding force of the third pattern portion  144  with the first pattern  152  is stronger than the bonding force of the third pattern portion  144  with the first substrate  110 . In contrast, since the second pattern portion  142  between the adhesion promoting layer  130  and the stamp mold  150  has a relatively strong bonding force with the adhesion promoting layer  130 , the second pattern portion  142  remains on the adhesion promoting layer  130 . 
     According to one or more embodiment, even when a burr is formed due to deposition of an excessive amount of UV-curable resin  140  in a region outside the pattern formation region A and between the first substrate  110  and the stamp mold  150 , since the burr is formed in the region outside the pattern formation region A, the burr is removed from the first substrate  110  together with the stamp mold  150 . Also, even when the stamp mold  150  is not accurately aligned with the first substrate  110 , the second pattern portion  142  is formed only in the desired pattern formation region A owing to the UV-curable resin  140  disposed on the adhesion promoting layer  130 . 
       FIGS. 2A to 2C  are cross-sectional views schematically illustrating a method of removing the resin coated on the stamp mold  150  according to an embodiment. The same reference numerals in  FIGS. 2A to 2C  as in  FIGS. 1A to 1F  denote the same elements, and redundant descriptions thereof will be omitted. 
     Referring back to  FIG. 1F , after the second pattern portion  142  is formed in the desired pattern formation region A on the first substrate  110 , the third pattern portion  144 , which is a residual resin, is removed from the stamp mold  150  in order to reuse the stamp mold  150 . 
     Referring to  FIG. 2A , an adhesive layer  220  is formed on a second substrate  210 . The adhesive layer  220  may be coated on an entire top surface of the second substrate  210 . The second substrate  210  may include any of a number of materials that has a relatively strong adhesive force with the adhesive layer  220 . In an embodiment, for example, the second substrate  210  may include glass, silicon, or plastic. 
     The adhesive layer  220  may include the same material as the adhesion promoting layer  130  described above, and redundant descriptions thereof will be omitted. The adhesive layer  220  may be formed by spin coating, drop dispensing or deposition. 
     However, the invention is not limited to the above process of increasing an adhesive force of the second substrate  210 . In an embodiment, for example, instead of coating the adhesive layer  220 , an oxygen plasma treatment or a UV ozone treatment may be performed on the top surface of the second substrate  210  to increase the adhesive force of the second substrate  210 . Hereinafter, for convenience sake, a region modified by the oxygen plasma treatment or the UV ozone treatment may also be referred to as the adhesive layer  220 . 
     Referring to  FIG. 2B , the stamp mold  150  having the third pattern portion  144  thereon, is pressed onto the second substrate  210  having the adhesive layer  220  thereon, so that the third pattern portion  144  on the stamp mold  150  is attached onto the adhesive layer  220  on the second substrate  210 . UV light may be irradiated onto the stamp mold  150  in order to increase the bonding force between the adhesive layer  220  and the third pattern portion  144 , but the invention is not limited thereto. 
     In an embodiment, a double-side tape may be used as the adhesive layer  220 . When the double-sided tape is used as the adhesive layer  220 , the irradiation of UV light onto the adhesive layer  220  may be omitted. 
     Referring to  FIG. 2C , when the stamp mold  150  is detached from the second substrate  210 , the third pattern portion  144  formed within the first pattern  152  of the stamp mold  150  is separated from the stamp mold  150  by being attached to the adhesive layer  220 . Thus, the stamp mold  150  without the third pattern portion  144  thereon may be reused in the method of forming an aligned pattern in a pattern formation region by using an imprint process. 
     As described above, according to the one or more embodiment, even when a burr is formed due to deposition of an excessive amount of resin outside a pattern formation region and between the transfer substrate and the stamp mold, the burr is removed from the transfer substrate together with the stamp mold. Also, even when the stamp mold is not accurately aligned with the transfer substrate, the transfer pattern may be formed only in the desired pattern formation region owing to the adhesion of the resin disposed with the adhesion promoting layer on which it is disposed. 
     It should be understood that the embodiments described herein should be considered in a descriptive sense only and not for purposes of limitation. Descriptions of features within each embodiment should typically be considered as available for other similar features in other embodiments.