WO2011126131A1

WO2011126131A1 - Pattern forming method and process for producing pattern substrates

Info

Publication number: WO2011126131A1
Application number: PCT/JP2011/058960
Authority: WO
Inventors: Tadashi Omatsu; Kunihiko Kodama; Kenichi Kodama
Original assignee: Fujifilm Corporation
Priority date: 2010-04-07
Filing date: 2011-04-05
Publication date: 2011-10-13
Also published as: JP2011222647A; TW201141687A

Abstract

The issue is to form a high-definition pattern having good etching resistance with good mass productivity by use of an imprinting technique. A resist layer (20m) is formed on a substrate (10), the resist layer (20m) comprising a resist composition (20), which is arranged as a plurality of discrete droplets, the resist composition (20) containing a polymerizable compound (21), a polymerization initiator (I) which is activated by light or an electron beam (L1), and a fluorine-containing polymerizable surfactant (22). A surface of a mold (30), which surface is provided with a predetermined protrusion and recess pattern, is pressed onto the resist layer (20m). The resist layer (20m) is cured by irradiation of the light or the electron beam (L1) to the resist layer (20m), and the mold (30) is released from a resist layer (40). [Selected Figure] Figure 1

Description

DESCRIPTION

PATTERN FORMING METHOD AND PROCESS FOR PRODUCING PATTERN SUBSTRATES

Technical Field

This invention relates to a pattern forming method using an imprinting technique. This invention also relates to a process for producing a pattern substrate by use of a pattern having been formed by the pattern forming method.

Background Art

In the fields of nano-order pattern formation for patterned media, semiconductor devices, and the like, a photoimprinting technique has attracted particular attention. The photoimprinting technique is a technique for forming a reversal pattern on a processing object with a transfer technique by the utilization of a micropattern having been formed on a mold. Specifically, the mold whose surface is provided with the predetermined pattern to be transferred is pressed against a liquid-state resist material having been arranged on a substrate, the resist material is then cured by irradiation of light to the resist material, and the pattern is thereby transferred to the substrate.

The photoimprinting technique enables simple and low-cost pattern formation by the use of a mold provided with a desiredpattern and is therefore expected as a next-generation production technique for microprocessing.

With the photoimprinting technique, problems are encountered in that, due . to pattern arrangement and substrate shape, non-uniformity arises in residual layer thickness between each of recesses after the imprinting and the substrate, and in that the accuracy of the obtained pattern thus becomes bad. In order for the aforesaidproblems to be eliminated, there have beenproposedmethods, wherein a resist is arranged in a specific pattern of discrete droplets in accordance with pattern arrangement, a recess volume, and a substrate shape. (Reference may be made to Patent Documents 1, 2, and 3.)

Also, as a method enabling droplets to be arranged on a substrate easily andwith a comparatively high accuracy, heretofore, the droplets are appliedon the substrate by use of an inkjet technique. For the inkjet technique, good jetting-out performance and good jetting-out stability are important. It has been known that the jetting-out performance and the jetting-out stability are affected by control of physical properties of the liquid to be jetted out.

For example, if the control of the physical properties of the liquid to be jetted out cannot be performed, and if the physical properties of the liquid thus deviate markedly from recommended ranges, the problems will occur in that abnormal states arise in droplet volume control and jetting-out direction control, in that shifts in positions of droplet deposition on the substrate thus arise, and in that droplets referred to as satellites, which droplets are other than the droplets to be jetted out, are jetted out and deposit on the substrate. In such cases, accurate pattern formation cannot be performed. Further, the jetting-out stability cannot be obtained owing to deterioration of the jetting-out accuracy due to staining of nozzles.

Furthermore, besides the aforesaid physical properties with respect to the jetting-out performance, the resist material is required to have mold releasability at the time of mold removal after curing, etching resistance during a lithography stage after pattern formation, pattern shape characteristics, such as rectangularity and roughness, characteristics of thin residual layer thickness, and in-plane uniformity.

Patent Document 4 discloses an imprint resist containing a fluorine resin as a principal ingredient. Good releasability is obtained by the containing of the fluorine resin as the principal ingredient. However, the viscosityof the disclosed resist is higher than a viscosity range appropriate for the inkjet, and therefore it is not always possible to arrange the resist in a desired pattern with good productivity. Also, because of a high fluorination rate, at the time of nano-order pattern formation, the etching resistance during a post-stage of imprinting is not obtained sufficiently.

Patent Document 5 proposes a technique/ wherein a resist composition containing a surfactant is used as a liquid to be jetted out, andwherein a large amount of the surfactant is adhered to regions of a mold surface, which regions correspond to droplet arrangement, such that wettability and releasability of the resist material with respect to the mold are kept good. Also, Patent Document 6 discloses the utilization of a surfactant in a silicon-containing resist composition, such that the releasability is enhanced.

Patent Document 1: U.S. Patent Application Publication No.

20050273012

Patent Document 2: U.S. Patent Application Publication No.

20050106321

Patent Document 3: U.S. Patent Application Publication No.

20090148619

Patent Document 4: Japanese Unexamined Patent Publication

No. 2006-110997

Patent Document 5: U.S. Patent Application Publication No.

20090136654

Patent Document 6: U.S. Patent Application Publication No.

20060036051

However, with the technique proposed in Patent Document 5, the pattern shape accuracy becomes bad due to accumulation of the surfactant on the mold surface, and therefore it is not always possible to apply the proposed technique to patterns of sizes smaller than several tens of nanometers.

Also, with the technique disclosed in Patent Document 6, the surfactant contained in the resist is apt to the mold surface. Figure 3 is an explanatory view showing states of a resist composition and a resist layer on a substrate in production stages A, B, and C in cases where the resist composition containing a non-polymerizable surfactant is used. Further, as illustrated at the production stages B, and C in Figure 3, the problems are encountered in that the surfactant is distributed unevenly in accordance with an arrangement pattern of the resist composition on the substrate, material physical properties, such as hydrophilic and hydrophobic characteristics and viscosity of the surfactant, and compatibility of the surfactant with the resist composition, and in that the resist at the uneven distribution regions (the regions hatched at the production stages B and C in Figure 3) is not cured and causes a pattern failure to occur. Further, with each of the techniques proposed in the aforesaid Patent Documents, since a quality deterioration rate of the mold becomes quick due to the surfactant, the problems are encountered with regard to mass productivity.

In view of the above circumstances, the primary object of the present invention is to provide a pattern forming method, wherein pattern formation with an imprinting technique is performed such that high-accuracy patterning is performed in nano-order pattern formation, and such that mass productivity and etching resistance are good.

Another object of the present invention is to provide aprocess for producing a pattern substrate, wherein a substrate is processed with a lithography technique by use of a mask having been formed by the pattern forming method, andwherein a pattern substrate having been subjected to patterning at a high accuracy is thereby produced.

Disclosure of Invention

The present invention provides a pattern forming method, comprising the steps of:

i) forming a resist layer on a substrate, the resist layer comprising a resist composition, which is arranged as a plurality of discrete droplets, the resist composition containing a polymerizable compound, a polymerization initiator which is activated by light or an electron beam, and a fluorine-containing polymerizable surfactant,

ii) pressing a surface of a mold, which surface is provided with a predetermined protrusion and recess pattern, onto the resist layer,

iii) curing the resist layer by irradiation of the light or the electron beam to the resist layer, and

iv) releasing the mold from the resist layer.

The fluorine-containing polymerizable surfactant has the function of a surfactant. The fluorine-containing polymerizable surfactant and the polymerizable compound are herein different substances. The polymerizable compound may contain fluorine. However, in such cases, the fluorine content in the polymerizable compound should be such that the characteristics of uneven distribution of the polymerizable compound to the surface of each of the droplets are sufficiently lower than the characteristics of uneven distribution of the fluorine-containing polymerizable surfactant to the surface of each of the droplets. Alternatively, in the cases described above, the polymerizable compound should have a structure substantially free from a fluoroalkyl group or a fluoroalkylether group. As the fluorine content described above, the fluorine content in the compound representedby following formula (CI) should be at most 5%. number offluorine atoms \ , /atomic weight of

. \in polymerizabl compound,/ \ fluorine atom _1ΛΛ

Fiuoraie content = —: — — —: :—— x 100

molecular weight of polvraenzaol compound

(CI)

The content of the polymerizable surfactant in the resist composition should preferably be at most 5 mass%.

The pattern forming method in accordance with the present invention should preferably be modified such that a fluorine-containing polymerizable compound is employed as the polymerizable surfactant, the fluorine-containing polymerizable compound having a plurality of pieces of at least one kind of a fluorine-containing group, which is selected from the group consisting of a fluoroalkyl group and a fluoroalkylether group, within a monomer of the polymerizable surfactant, at least two pieces of the fluorine-containing group among the plurality of pieces of the fluorine-containing group being spaced apart from each other by a linking group having a carbon number of at least 2. Also, in such cases, the pattern forming method in accordance with the present invention should more preferably be modified such that each of at least two pieces of the fluorine-containing group is a fluoroalkyl group having a carbon number of at least 2. Further, each of at least two pieces of the fluorine-containing group should preferably be a trifluoromethyl group.

Furthermore, the pattern forming method in accordance with the present invention should preferably be modified such that a polyfunctional monomer, which crosslinks bypolymerization and forms a polymer having a three-dimensional structure, is employed as the polymerizable compound. In such cases, the polyfunctional monomer should preferably have at least one bivalent or trivalent aromatic group. Also, it is preferable that a monomer having a cyano group is employed as the polymerizable compound.

The term "polyfunctional monomer" as used herein means the monomer having a plurality of pieces of an ethylenically unsaturated double bond.

Also, the pattern forming method in accordance with the present invention should preferably be modified such that, before the resist layer is arranged on the substrate, a surface binding agent or an adhesion agent for binding and adhering a surface of the substrate, on which surface the resist layer is to be arranged, and the resist layer with each other is applied to the surface of the substrate, on which surface the resist layer is to be arranged.

The present invention also provides a process for producing a pattern substrate, comprising:

using the resist layer, which has been pattern-formed on the substrate by the pattern forming method in accordance with the present invention, as a mask, and

forming a protrusion and recess pattern, which is obtained in accordance with the pattern of the resist layer, on a surface of the substrate by use of a lithography technique.

With the pattern forming method in accordance with the present invention, the resist layer is formed on the substrate, the resist layer comprising the resist composition, which is arranged as the plurality of the discrete droplets, the resist composition containing the polymerizable compound, the polymerization initiator which is activated by light or an electron beam, and the fluorine-containing polymerizable surfactant. With the resist layer, wherein the fluorine content in the resist composition is low, the viscosity of the resist composition and the etching resistance of the resist material after being cured are kept appropriately. Also, with the resist layer, in which the fluorine-containing polymerizable surfactant is contained, the pattern formation failure and mold deterioration due to uneven distribution, adhesion, and accumulation of the surfactant are not promoted, and the mold releasability is kept good by a fluorine containing site.

Therefore, with the pattern forming method in accordance with the present invention, the pattern formation with the imprinting technique is performed such that the high-accuracy patterning is performed in the nano-order pattern formation, and such that the mass productivity and the etching resistance are good.

Also, with the process for producing a pattern substrate in accordance with the present invention, wherein the substrate is processed with the lithography technique by use of the resist pattern, which has been prepared by the pattern forming method in accordance with the present invention, as the mask, the pattern substrate having been subjected to patterning at a high accuracy is produced.

Brief Description of Drawings

Figure 1 is an explanatory sectional view showing an embodiment of the pattern forming method in accordance with the present invention and an embodiment of the process for producing a pattern substrate in accordance with the present invention,

Figure 2 is an explanatory sectional view showing a constitution of a droplet of a resist composition, and

Figure 3 is an explanatory view showing states of a resist composition and a resist layer on a substrate in production stages A, B, and C in cases where the resist composition containing a non-polymerizable surfactant is used.

Best Mode for Carrying Out the Invention

[Pattern Forming Method]

An embodiment of the pattern forming method and an embodiment of the process for producing a pattern substrate in accordance with the present invention will be described hereinbelow with reference to Figure 1. In Figure 1, A to E show an embodiment of the pattern forming method in accordance with the present invention. For clearness, scales of respective elements are altered appropriately. (Resist Applying Stage)

Firstly, as illustrated at A in Figure 1, a substrate 10 is prepared. Also, as illustrated at B in Figure 1, a resist composition 20 is arranged as a plurality of discrete droplets on the substrate 10. The resist composition 20 contains a polymerizable compound 21 (not shown) , a polymerization initiator I (not shown) which is activated by light or an electron beam, and a fluorine-containing polymerizable surfactant 22 (not shown) . Thus a resist layer 20m comprising the resist composition 20 is formed on the substrate 10.

Though the substrate 10 should preferably have good surface smoothness, no limitation is particularly imposed upon the substrate 10. In this embodiment of the pattern forming method in accordance with the present invention, wherein the resist layer 20m is cured by the irradiation with light or an electron beam LI (hereinbelow referred to as the light LI) , it is necessary for either one of the substrate 10 and a mold 30 used in a post-stage to have transparency with respect to the light LI . The term "transparency" as used herein means that either one of the substrate 10 and the mold 30 has a transmittance capable of allowing the light LI in an amount capable of curing the resist composition 20 to reach the resist layer 20m. In cases where the transmittance with respect to the light LI is at least 1%, the curing of the resist composition 20 is possible. However, the transmittance with respect to the light LI should preferably be at least 10%, and should more preferably be at least 50%.

Examples of the materials for the substrate 10 include aluminum, glass, silicon, quartz, and an SiC^/Si substrate comprising a silicon layer and a thermal oxide film formed on a surface of the silicon layer. One of the above-enumerated substrate materials may be used alone, or at least two of the above-enumerated substrates may be used in combination.

Also, before the droplets of the resist composition 20 are arranged on a pattern forming surface 10S of the substrate 10, the pattern forming surface 10S shouldpreferablybe subjected to surface treatment for binding and adhering the pattern forming surface 10S and the resist composition to each other. As the surface treatment, there may be mentioned the treatment for forming a film of a coupling agent acting as a surface binding agent on the substrate 10, the coupling agent comprising a first functional group, which as binding ability with the substrate surface, and a second functional group, which has the binding ability with the resist layer 20m.

In so far as the bindingwith the substrate surface is possible, the first functional group is not limited particularly and may be selected appropriately from known functional groups in accordance with use applications. Examples of the first functional groups include an alkoxysilane site, a carboxylic acid anhydride site having crosslinking ability with an OH group, and a halide site.

In so far as the binding with the resist layer 20m (the resist composition 20) is possible, the second functional group is not limited particularly andmay be selected appropriately in accordance with the composition of the resist composition 20, and the like, from known functional groups, which bind with the resist layer 20m by a bond, such as a covalent bond, a hydrogen bond, an ionic bond, and a van der Waals bond.

Further, the surface binding agent should preferably have characteristics such that the binding of the substrate 10 and the resist layer 20m with each other is strengthened, and such that the possibility of removal of a resist layer residue after substrate processing with etching, or the like, has been performed does not become bad. Therefore, the surface binding agent should preferably be removable with oxygenplasma treatment, an oxygen ashing treatment, or UV ozone treatment after the substrate processing.

Examples of the surface binding agents include a silane coupling agent and a carboxylic acid anhydride. A technique for forming a film of the surface binding agent is not limited particularly and may be selected appropriately from liquid phase techniques, such as a spin coating technique, a spray coating technique, a dip coating technique, and an immersion technique; and a vapor phase technique, such as a vacuum evaporation technique.

Also, a layer of a different material (an etching-retardant material layer, such as a metal layer) may be formed as a mask layer between the pattern forming surface 10S of the substrate 10 and the resist layer 20 (or a layer of the surface binding agent) . In such cases, by appropriate selection of reactivity of a system of a reactive gas, which is employed in the etching stage performed as the post stage, with respect to the resist, the substrate 10 which is the processing object, and the mask layer, a processing margin is widened, and a processed substrate having a higher quality is prepared.

The arrangement of the droplets of the resist composition 20 should preferably be adjusted in accordance with the shape of the pattern to be formed, a protrusion and recess density, a recess volume, and wet spread characteristics of the resist droplets. By the adjustment described above, it is possible to suppress a pattern loss and inclusion of air at the next mold pressing stage, and non-uniformity in thickness (i.e., residual layer thickness) between each of the resist layer recesses after the pattern formation has been performed and the substrate 10.

In so far as the aforesaid adjustment is possible, a technique for arranging the droplets is not limited particularly and may be selected from a printing technique and an inkjet technique. The inkjet technique is preferable for its good arrangement accuracy and easiness of the adjustment of arrangement positions and the amount of a resin formed as a film. An arrangement pattern may be designed with a technique, wherein test imprinting is performed experimentally by use of an arrangement test pattern, and wherein the arrangement pattern is designed in accordance with relationships among the obtained wet spread corresponding to a pattern on the mold, the obtained distribution of the residual layer thickness, and the arrangement test pattern. Alternatively, an optimum arrangement pattern may be obtained by calculation from the pattern on the mold, predicted anisotropy of the wet spread of the resist, and the distribution of the wet spread of the resist. For example, in the cases of a line-like pattern, a wetting rate of the resist droplets utilizing a capillary force to the direction along the line on the mold surface is quick, and the wetting rate of the resist droplets to the direction normal to the line is slow. Therefore, it is possible to predict the anisotropy of the wet spread of the resist droplets to a certain extent.

An applied amount of the droplets of the resist composition 20 should preferably be such that the thickness of the resist layer 20m after the pressing with the mold is selected within the range of 5nm to 200nm.

Figure 2 is an explanatory sectional view showing a constitution of the droplet 20 of the resist composition 20. The droplet 20 constituted of the resist composition 20 comprises a polymerizable compound 201, which contains the aforesaid polymerizable compound 21 as the principal ingredient that constitutes a proportion, expressed in terms of a weight content, higher than 50 wt%. The droplet 20 also comprises a fluorine-containing polymerizable surfactant 202, which contains the aforesaid fluorine-containing polymerizable surfactant 22 as the principal ingredient that constitutes a proportion, expressed in terms of a weight content, higher than 50 wt%. Each of the polymerizable compound 201 and the fluorine-containing polymerizable surfactant 202 contains the polymerization initiator I (not shown) which is activated by the light LI. The polymerizable compound 201 may contain the fluorine-containing polymerizable surfactant 22 in a small amount of less than 50 wt%. Also, the fluorine-containing polymerizable surfactant 202 may contain the polymerizable compound 21 in a small amount of less than 50 wt%.

Ordinarily, a fluorine-containing compound has the characteristics such that the fluorine-containing compound is distributed unevenly at an interface layer (a surface) within a resin layer. As a fluorine substitution rate in the compound is high, the uneven distribution characteristics become high. In this embodiment, as illustrated in Figure 2, the fluorine-containing polymerizable surfactant 202 is present in the droplet 20 so as to cover the surface of the polymerizable compound 201. With the constitution described above, at the time of the application of the droplets 20 onto the substrate 10, the surface energy is controlled appropriately. Therefore, the jetting-out operation is performed with high stability.

In cases where the mold releasability and the keeping of the pattern quality in the dry etching stage performed as the post stage are taken into consideration, the content of the fluorine-containing polymerizable surfactant 22 in the droplets 20 should preferably be such that the thickness at the resist layer surface after the pattern formation is at most l.Onm, preferably at most 0.7nm, more preferably at most 0.5nm. For the aforesaid content, the content of the fluorine-containing polymerizable surfactant 22 in the droplets 20 should preferably be at most 5 mass%, and should more preferably be at most 1 mass%. Details of the resist composition 20 will be described later.

{Pattern Forming Stage)

Thereafter, as illustrated at C and D in Figure 1, the mold 30 is pressed against the resist layer 20m from above the top surface of the substrate 10. After the recesses of the pattern of the mold 30 are thus filled with the resist composition 20, the light LI is irradiated to cure the resist layer 20m. In Figure 1, D shows the example, wherein a substrate having good transparency with respect to the light LI is employed as the substrate 10, and wherein the light LI is irradiated from the substrate side. In cases where the substrate 10 has good transparency with respect to the light LI as in this embodiment, no limitation is particularly imposed upon the mold 30. However, as described above, in cases where the substrate 10 is not transparent with respect to the light LI, since it is necessary for the light LI to be irradiated from the side of the mold 30, it is necessary that the mold 30 us transparent with respect to the light LI .

With the pattern formingmethod in accordance with the present invention, marked effects are obtained with respect to a region in which the pattern size is fine. Also, particularly marked effects are obtained with respect to a region in which a pattern width is at most 30nm, and in which a pattern aspect ratio is at least 2.

As a technique for forming the mold 30, the pattern may be formed on the surface of a substrate acting as the mold by use of a conventional technique, such as an electronbeam drawing technique, a transfer technique with an exposure machine, a transfer technique with imprinting, and a combination of the aforesaid techniques. Pattern processing is performed on the substrate surface with an etching process in accordance with the formed pattern, and the substrate on which a desired master pattern has been processed is thus prepared as the mold.

The pressing of the mold 30 against the resist layer 20m should preferably be performed under a helium atmosphere or under reduced pressure. With the constitution described above, the inclusion and retention of air between the mold 30 and the resist resin layer 20m are suppressed, and formation of a pattern-unformed region due to gas ingredients is avoided.

As illustrated in Figure 2, at the time at which the mold 30. is pressed against the resist layer 20m, the fluorine-containing polymerizable surfactant 22 is distributed unevenly at the surface of each of the droplets 20. Therefore, after the pressing, at the surface of the mold 30, the fluorine-containing polymerizable surfactant 22 is distributed unevenly at the interface layer between the mold and the resist. The fluorine-containing compound has low adhesion characteristics with respect to the mold 30 and has lubricity. Therefore, with the constitution described above, good releasability of the mold 30 is obtained in the mold release stage after the curing of the resist layer 20m.

In order for the releasability to be enhanced even further, the pattern surface of the mold 30 should preferably be subjected to release treatment. As the release treatment, a technique for applying a release agent to the pattern surface of the mold 30 is simple. As the release agent, a fluorine-containing polymers or a silicone type resin are preferable. Particularly, a perfluoropolyether (PFPE) or a resin having a perfluoroalkyl chain is preferable.

A technique for forming a film of the release agent is not limited particularly and may be selected appropriately from the liquid phase techniques, such as the dip coating technique, the spin coating technique, the spray coating technique, and the immersion technique; and the vapor phase technique, such as the vacuum evaporation technique.

Also, as a different release treatment technique, an inorganic layer having little interaction with the resist may be located as the release layer on the surface of the mold 30. Examples of the inorganic layers include a diamond-like carbon (DLC) layer and a fluorinated DLC layer. Alternatively, a different fluorine-containing inorganic layer may be employed.

Finally, as illustrated at E in Figure 1, after a polymer resist layer 40 has been formed by the curing of the resist layer 20m, the mold 30 is released from the polymer resist layer 40, and a resist pattern 1 constituted of the polymer resist layer 40 is formed on the substrate 10.

Such that the quality of the pattern formed on the substrate 10 after the lithography stage, such as the dry etching stage performed as the post stage, is kept good, the mean thickness (the mean residual layer thickness) of the recesses of the resist layer 40 should preferably be at most 15nm, should more preferably be at most lOnm, and should most preferably be at most 5nm. Also, a standard deviation value (σ value) of the residual layer thickness should preferably be at most 5nm, should more preferably be at most 3nm, and should most preferably be at most lnm.

If the residual layer thickness is large, deterioration of the shape of the resist pattern will increase in the stage of exposing of the substrate surface acting as the processing object in the dry etching stage, and it will become more difficult to obtain the pattern of the desired shape after the etching.

In so far as little pattern loss arises, no limitation is imposed upon the technique for releasing the mold 30. Examples of the techniques for releasing the mold 30 include a technique for releasing the mold 30 little by little from a pattern edge area; a technique (a pressure release technique) , wherein the release is performed by pressure application from the mold side such that the force exerted upon the resist layer on a boundary line, at which the mold is released from the resist layer, is suppressed; and a technique (a heating assisted release technique) , wherein the release is performed with the vicinity of the resist layer being in a heated state, such that the adhesion force of the resist layer and the mold surface with each other is suppressed at the interface between the mold and the resist, such that a Young's modulus of the resist layer is decreased, and such that breakage due to deformation is suppressed through an improvement of brittleness. The above-enumerated techniques for releasing the mold 30 may be used in combination.

With the embodiment of the pattern forming method in accordance with the present invention, wherein the fluorine-containing polymerizable surfactant 22 is employed as the surfactant, fluidity at the mold interface becomes lower than the cases where an ordinary surfactant free from the polymerizable properties is used, and resistance force at the time of the release in a normal temperature state becomes larger than the aforesaid cases . Therefore, in the embodiment of the pattern forming method in accordance with the present invention, the heating assisted release technique should preferably be employed.

In cases where the heating assisted release technique is performed, it is possible to use a release apparatus provided with a mechanism in which the heating is controlled at chucking sections for the mold and the substrate, a mechanism in which the mold release is performed by chucking the mold and the substrate within a temperature controlled chamber, a temperature control mechanismwith radiant heat, or the like. The release of themold 30 maybe performed little by little from a peripheral area, or may be performed little by little from one edge area.

As described above under the title "Background Art, " in cases where the resist composition contains the surfactant, the droplets are wet spread due to the pressing with the mold, such that the surfactant is distributed unevenly in accordance with the arrangement pattern of the resist composition on the substrate. In such cases, the resist at the uneven distribution regions is not cured and causes a pattern failure to occur. Figure 3 is an explanatory view showing how the droplets 20 undergo the wet spread at the time at which the droplets 20 are arranged on the substrate surface 10S at the production stage A and are pressed by the mold from above the plane of the sheet of Figure 3. For clearness, Figure 3 shows the cases where the mold having a smooth surface is pressed against the droplets 20. At the production stage B in Figure 3, there is illustrated how the droplets 20 are collapsed halfway during the pressing and undergo the wet spread. The surfactant is distributed unevenly at the regions hatched at the production stage B in Figure 3 and on the mold surface (not shown) . As illustrated at the production stage C in Figure 3, when the pressing is continued, an uneven distribution pattern of the fluorine-containing polymerizable surfactant 22 is formed as indicated by the reference numeral 202 in accordance with the arrangement of the droplets 20. At the production stage C in Figure 3, actually, the fluorine-containing polymerizable surfactant 22 is present also on the surfaces of the regions indicated by the reference numeral 201. However, for clearness, the presence of the fluorine-containing polymerizable surfactant 22 on the surfaces of the regions indicated by the reference numeral 201 is not shown. Also, in cases where, for example, a substance highly compatible with the surfactant 22 has been applied as the release agent to the mold surface, it often occurs that the surfactant 22 is apt to be distributed unevenly at an uppermost part of an approximately center area of each of the droplets 20, which uppermost part firstly comes into contact with the mold surface. Therefore, the resist layer 20m is cured by the irradiation with the light LI in the state in which the resist layer 20m has the uneven distribution pattern as illustrated at the production stage C in Figure 3 or the pattern, in which the surfactant 22 is distributed unevenly at the approximately center area of each of the droplets 20.

Heretofore, since the surfactant distributed unevenly does not have the polymerizability, the surfactant that is present at the surface of contact with the mold 30 deteriorates the pattern surface of the mold 30 due to the adhesion and accumulation of the surfactant on the mold 30. Also, heretofore, since the surfactant distributed unevenly at the regions hatched at the production stage C in Figure 3 cannot be cured, a pattern loss (an inkjet arrangement pattern-like defect) occurs.

The resist composition employed in the embodiment of the pattern forming method in accordance with the present invention contains the fluorine-containing compound that is polymerizable (i.e., the fluorine-containing polymerizable surfactant) as the surfactant. Ordinarily, the fluorine-containing compound has the characteristics such that the fluorine-containing compound is distributed unevenly at an interface layer within a resin layer. As a fluorine substitution rate in the compound is high, the uneven distribution characteristics become high. In the cases of the imprinting technique, to which this embodiment of the pattern forming method in accordance with the present invention is applied, the fluorine-containing compound is distributed unevenly principally at the interface between the cured resist layer and the mold, and therefore the deterioration of the mold pattern surface constitutes the problems with regard to the mass productivity.

The purpose of the containing of the fluorine-containing compound in the resist composition is to enhance the mold releasability at the release stage by virtue of the characteristics of the fluorine-containing compound such that the fluorine-containing compound is distributed unevenly at the interface layer between the mold and the resist and has the low adhesion properties and the lubricity with respect to the mold. Another purpose of the containing of the fluorine-containing compound in the resist composition is to stabilize film formability with the techniques, such as the inkjet technique and the printing technique, through control of surface energy at the time of film formation of the resist on the substrate.

In the embodiment of the pattern forming method in accordance with the present invention, the fluorine-containing polymerizable surfactant is employed as the fluorine-containing compound which is distributed unevenly at the interface layer of the resist layer on the side of the mold. In the embodiment of the pattern forming method in accordance with the present invention, the polymerizable group of the fluorine-containing polymerizable surfactant is a functional group having polymerization reactivity with a monomer constituting a principal ingredient of the resist composition and is preferably a (meth)acryl group. The inventors have found that, in cases where the polymerizable group is contained in the fluorine-containing compound, the deterioration of the mold quality due to the adhesion and the accumulation of the fluorine-containing compound on the mold after the imprinting has been performed is suppressed, and good releasability and good film formation stability are kept.

Specifically, in cases where the fluorine-containing polymerizable surfactant is employed as the surfactant in the resist composition 20, the surfactant located at the hatched regions 202 at the production stage C in Figure 3 undergoes the polymerization in the same manner as that for the polymerizable compound regions 201 and is cured as a part of the pattern having good pattern formability and good etching resistance. Therefore, the risk of the pattern loss occurring due to the uneven distribution of the surfactant 22 becomes markedly low. Also, since the surfactant 22 present at the surface of contact with the mold 30 is polymerized and cured, the deterioration of the pattern quality due to the adhesion of the surfactant 22 to the pattern surface of the mold 30 is suppressed. Further, by appropriate selection of a surfactant that is efficient from the view points of the surface uneven distribution characteristics, the interface activating ability, such as the surface stabilizing performance with the uneven distribution, and the releasability, the amount of the surfactant used is reduced markedly, and adverse effects of the occurrence of quality deterioration in shape after etching in accordance with the distribution of the amount of the surfactant on a two-dimensional plane are suppressed to a substantially imperceptible level.

With respect to the polymerizable compound 21 and the fluorine-containing polymerizable surfactant 22 constituting the principal ingredients of the resist composition 20, the inventors performed material designing for obtaining the resist characteristics of good releasability and good etching resistance.

The resist composition 20 will hereinbelow be described in detail. The resist composition 20 is a curable composition for imprints comprising at least one fluorine-containing polymerizable surfactant 22, the polymerizable compound 21, and the photopolymerization initiator I.

The resist composition 20 may contain a mono- or more functional monomer ingredient having a polymerizable functional group for the purpose of enhancing the etching resistance by, for example, aiming at development of a crosslinkable function through the provision of a pol functional polymerizable group, enhancing a carbon density, enhancing a total amount of bond energy, or suppressing the content of a high electronegativity moiety, such as 0, S, or N, contained in the cured resin. Also, if necessary, the resist composition 20 may contain a substrate coupling agent, a volatile solvent, an antioxidant, and the like.

As the substrate coupling agent, it is possible to employ the same materials as the aforesaid adhesion treating agents for the substrate. The content of the substrate coupling agent in the resin composition 20 may be such that the substrate coupling agent is contained to an extent of arrangement at the interface between the substrate and the resist layer. . The content of the substrate coupling agent in the resin composition 20 may be at most 10 mass%, should preferably be at most 5 mass%, should more preferably be at most 2 mass%, and should most preferably be at most 0.5 mass%.

From the view points of entering of solid ingredients (the ingredients other than the volatile solvent ingredient) in the resist composition 20 into the pattern formed on the mold 30 and the wet spread characteristics to the mold, the viscosity of the solid ingredients of the resist composition 20 should preferably be at most l,000mPa' S, should more preferably be at most 100mPa^#s, and should most preferably be at most 20mPa' S . However, in cases where the inkjet technique is utilized, the viscosity of the solid ingredients of the resist composition 20 should preferably be at most 15mPa*s at the room temperature or at a temperature within a temperature range in which the temperature control is possible with a heat at the time of the jetting-out operation. Also, from the view point of obtaining the jetting-out stability with the inkjet technique, a surface tension of the resist composition should preferably be selected within the range of 20 to 35 (mN/m) .

(Polymerizable Compound)

As described above under the title "Background Art, " from the view point of the etching resistance, the fluorine content in the polymerizable compound acting as the principal ingredient of the resist composition 20 should preferably be small. Therefore, in the embodiment of the pattern forming method in accordance with the present invention, as the polymerizable compound 21 acting as the principal ingredient of the resist composition 20, there is employed the polymerizable compound, in which the fluorine content in the compound represented by formula (CI) is at most 5%, or which is substantially free from a fluoroalkyl group or a fluoroalkylether group.

Though it is not limited particularly, the polymerizable compound 21 should preferably have good quality, such as the pattern accuracy after the etching or the etching resistance. The inventors have found that a polyfunctional monomer, which crosslinks by polymerization and forms a polymer having a three-dimensional structure, is employed as the polymerizable compound 21, and that the polyfunctional monomer should preferably have at least one bivalent or trivalent aromatic group.

In the cases of the resist having a three-dimensional structure after the curing (the polymerization) , shape keeping characteristics after the curing treatment are good, and it is possible to suppress the problems in that a stress exerted upon the resist is concentrated upon a specific area of the resist structure due to the adhesion force of the mold and the resist with each other at the time of the mold release and causes the pattern to undergo plastic deformation.

However, if the proportion of the polyfunctional monomer, which crosslinks by the polymerization and forms the polymer having the three-dimensional structure, and the density of the moiety, which forms the three-dimensional crosslinks after the polymerization, increase, the Young's modulus after the curing will become large, deformability will become bad, and film brittleness will become bad. Therefore, there will be the risk that breakage will be apt to occur at the time of the mold release. Particularly, in cases where a pattern, in which the pattern width is at most 30nm, and in which the pattern aspect ratio is at least 2, is formed such that the residual layer thickness is at most lOnm, if the formation over a wide area of a hard disc pattern or a semiconductor pattern is attempted, the probability that peeling and breaking off of the pattern will occur will become high.

Therefore, the proportion of the polyfunctional monomer contained in the polymerizable compound 21 should preferably be at least 10 mass%, should more preferably be at least 20 mass%, should particularly preferably be at least 30 mass%, and should most preferably be at least 40 mass%.

Also, the inventors have found that a crosslink density representedby formula (C2) shownbelow shouldpreferablybe selected within the range of 0.01 piece/nm² to 10 pieces/nm², should more preferably be selected within the range of 0.1 piece/nm² to 6 pieces/nm², and should most preferably be selected within the range of 0.5 piece/nm² to 5.0 pieces/nm². The crosslink density of a composition is obtained by calculating the crosslink density of each molecule and making a calculation from a weight average. Alternatively, the crosslink density of a composition is obtained bymeasuring a density of the composition after the curing, andmaking a calculation from a weight average value of each value with respect to Mw and (Nf-1) and with formula (C2) . a x Dc

Da = CKf- w (C2) wherein Da represents the crosslink density of one molecule, Dc represents the density after the curing, Nf represents the number of the acrylate functional group contained in one molecule of the monomer, Na represents the Avogadro constant, andMw represents the molecular weight.

No limitation is particularly imposed upon the polymerizable functional group of the polymerizable compound 21. A methacrylate group and an acrylate group are preferable for good reactivity and good stability. The acrylate group is more preferable.

The dry etching resistance may be evaluated with an Ohnishi parameter and a ring parameter of the resist composition. A resist composition having a small Ohnishi parameter and a large ring parameter has excellent dry etching resistance. In the embodiment of the pattern forming method in accordance with the present invention, the Ohnishi parameter of the resist composition 20 should preferably be at most 4.0, should more preferably be at most 3.5, and should most preferably be at most 3.0. Also, the ring parameter of the resist composition 20 shouldpreferablybe at least 0.1, should more preferably be at least 0.2, and should most preferably be at least 0.3.

In order for each of the aforesaid parameters to be obtained, material parameter values are calculated with respect to the ingredients of the resist composition 20 other than the volatile solvent ingredient in accordance with the structural formulae and by use of the calculation formula shown below, and a value calculated by averaging the material parameter values over the entire composition in accordance with formulation weight ratios is taken as each of the aforesaid parameters . Therefore, the polymerizable compound 21 constituting the principal ingredient of the resist composition 20 should preferably be selected with the other ingredients in the resist composition 20 and the aforesaidparameters being taken into consideration.

Ohnishi parameter = (total atom number in compound) / (carbon atom number in compound) - (oxygen atom number in compound)

Ring parameter = (carbon mass that forms ring structure) / (total mass of compound)

Examples of the polymerizable compounds 21 include the polymerizable monomers, and oligomers obtained from polymerization of several units of the aforesaid polymerizable monomers. From the view points of the pattern formability and the etching resistance, the polymerizable compound 21 should preferably contain at least one of the members selected from the group consisting of a polymerizable monomer (Ax) and compounds described in paragraphs [0032] to [0053] of Japanese Unexamined Patent Publication No. 2009-218550.

-Polymerizable Monomer (Ax) -

The polymerizable monomer (Ax) is represented by general formula (I) shown below.

(I) wherein Ar represents a bivalent or trivalent aromatic group, which may have a substituent group, X represents a single bond or an organic linking group, R¹ represents a hydrogen atom or an alkyl group, which may have a substituent group, an n represents a number of 2 or 3.

In general formula (I), Ar represents a bivalent aromatic group (i.e., an arylene group) in the cases of n=2, and represents a trivalent aromatic group in the cases of n=3. Examples of the arylene group include a hydrocarbon type arylene group, such as a phenylene group or a naphthylene group; and a heteroarylene group, in which indole, carbazole, or the like, acts as a linking group. The arylene group should preferably be a hydrocarbon type arylene group. From the view points of the viscosity and the etching resistance, the arylene group should more preferably be a phenylene group. The arylene group may have a substituent group. Examples of preferable substituent groups include an alkyl group, an alkoxy group, a hydroxyl group, a cyano group, an alkoxycarbonyl group, an amide group, and a sulfonamide group.

Examples of the organic linking groups represented by X include an alkylene group, an arylene group, and an aralkylene group, each of which may contain a heteroatom in the chain. Among the above-enumerated groups, an alkylene group and an oxyalkylene group are preferable. An alkylene group is more preferable. It is particularly preferable that X represents a single bond or an alkylene group.

R¹ should preferably represent a hydrogen atom or a methyl group. It is more preferable that R¹ represents a hydrogen atom. In cases where R¹ has a substituent group, though no limitation is particularly imposed upon the substituent group, examples of preferable substituent groups include a hydroxyl group, a halogen atom (excluding fluorine), an alkoxy group, and an acyloxy group. Also, n represents a number of 2 or 3, and shouldpreferably represent a number of 2.

From the view point of decreasing the composition viscosity, the polymerizable monomer (Ax) should preferably be a polymerizable monomer represented by general formula (I-a) or (I-b) shown below.

( I - a ) ( I - b )

wherein each of X¹ and X² independently represents a single bond or an alkylene group, which may have a substituent group having a carbon number of 1 to 3, R¹ represents a hydrogen atom or an alkyl group, which may have a substituent group.

In general formula (I-a), X¹ should preferably represent a single bond or a methylene group. From the view point of decreasing the viscosity, a methylene group is more preferable. The preferable range of X² is identical with the preferable range of X¹.

R¹ has the same meaning as R¹ in general formula (I) , and the preferable range of R¹ is identical with the preferable range of R¹ in general formula (I) .

The polymerizable monomer (Ax) should preferably be a liquid at a temperature of 25°C. In such cases, at the time of an increase of an adding amount, the occurrence of foreign materials is suppressed.

From the view point of the pattern formability, the viscosity of the polymerizable monomer (Ax) at a temperature of 25°C should preferably be less than 70mPa'S, should more preferably be at most 50mPa'S, and should most preferably be at most 30mPa-s.

Specific examples of preferable polymerizable monomers (Ax) will be shown below. R¹ has the same meaning as R¹ in general formula (I) . From the view point of the curability, R¹ should preferably represent a hydrogen atom. The embodiment of the pattern forming method in accordance with the present invention is not limited to the specific examples shown below.

Among the specific examples shown above, the compounds shown below are liquids at a temperature of 25°C, have a low viscosity and good curability, and are therefore particularly preferable.

From the view points of improvements in the composition viscosity, the dry etching resistance, the aptitude for imprinting, and the curability, if necessary, the polymerizable monomer (Ax) and a polymerizable monomer other than the polymerizable monomer

(Ax) should preferably be used in combination in the resist composition 20.

-Other Polymerizable Monomer- Examples of the other polymerizable monomers include a polymerizable unsaturated monomer having one to six ethylenically unsaturated bond-containing groups; a compound (an epoxy compound) having an oxirane ring; a vinyl ether compound; a styrene derivative; a compound having a fluorine atom; a propenyl ether or a butenyl ether. From the view point of the curability, a polymerizable unsaturated monomer having one to six ethylenically unsaturated bond-containing groups is preferable.

From the view points of the aptitude for imprinting, the dry etching resistance, the curability, and the viscosity, of the other polymerizable monomers enumerated above, the compounds described in paragraphs [0032] to [0053] of Japanese Unexamined Patent

Publication No. 2009-218550 may be contained more preferably.

The polymerizable unsaturated monomer (the mono- to hexa-functional polymerizable unsaturated monomer) having one to six ethylenically unsaturated bond-containing groups, which monomer may be contained as the other polymerizable monomer, will be described hereinbelow.

Examples of the polymerizable unsaturated monomers (the monofunctional polymerizable unsaturated monomers) having one ethylenically unsaturated bond-containing group include 2-acryloyloxyethyl phthalate, 2-acryloyloxy-2-hydroxyethyl phthalate, 2-acryloyloxyethylhexahydro phthalate, 2-acryloyloxypropyl phthalate, 2-ethyl-2-butylpropanediol acrylate, 2-ethylhexyl (meth) acrylate, 2-ethylhexylcarbitol

(meth) acrylate, 2-hydroxybutyl (meth) acrylate, 2-hydroxyethyl

(meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-methoxyethyl

(meth) acrylate, 3-methoxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, an acrylic acid dimer, benzyl (meth) acrylate, 1- or 2-naphtyl (meth) acrylate, butanediol mono (meth) acrylate, butoxyethyl (meth) acrylate, butyl (meth) acrylate, cetyl

(meth) acrylate, ethylene oxide-modified (hereinbelow referred to as "EO-modified") cresol (meth) acrylate, dipropylene glycol (meth) acrylate, ethoxylated phenyl (meth) acrylate, ethyl

(meth) acrylate, isoamyl (meth) acrylate, isobutyl (meth) acrylate, isooctyl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl

(meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentanyloxyethyl (meth) acrylate, isomyristyl (meth) acrylate, lauryl (meth) acrylate, methoxydipropylene glycol

(meth) acrylate, methoxytripropylene glycol (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, methoxytriethylene glycol (meth) acrylate, methyl (meth) acrylate, neopentyl glycol benzoate (meth) acrylate, nonylphenoxypolyethylene glycol (meth) acrylate, nonylphenoxypolypropylene glycol (meth) acrylate, octyl (meth) acrylate, paracumylphenoxyethylene glycol

(meth) acrylate, epichlorohydrin-modified (hereinbelow referred to as "ECH-modified") phenoxy acrylate, phenoxyethyl (meth) acrylate, phenoxydiethylene glycol (meth) acrylate, phenoxyhexaethylene glycol (meth) acrylate, phenoxytetraethylene glycol (meth) acrylate, a polyethylene glycol (meth) acrylate, a polyethylene glycol-polypropylene glycol (meth) acrylate, a polypropylene glycol

(meth) acrylate, stearyl (meth) acrylate, EO-modified succinic acid

(meth) acrylate, tert-butyl (meth) acrylate, tribromophenyl (meth) acrylate, EO-modified tribromophenyl (meth) acrylate, tridodecyl (meth) acrylate, p-isopropenyl phenol, styrene, cx-methylstyrene, and acrylonitrile.

Among the above-enumerated polymerizable unsaturated monomers, a monofunctional (meth) acrylate having an aromatic structure and/or an alicyclic hydrocarbon structure is preferable for improvement of the dry etching resistance. Examples of preferable monofunctional (meth) acrylates of the type described above include benzyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentanyloxyethyl (meth) acrylate, isobornyl (meth) acrylate, and adamantyl (meth) acrylate. Benzyl (meth) acrylate is particularly preferable.

As the other polymerizable monomer, it is also preferable to employ a polyfunctional polymerizable unsaturated monomer having two ethylenically unsaturated bond-containing groups. Examples of bifunctional polymerizable unsaturated monomers having two ethylenically unsaturated bond-containing groups, which monomers may be used preferably, include diethylene glycol monoethyl ether (meth) acrylate, dimethylol-dicyclopentane di (meth) acrylate, di (meth) acrylated isocyanurate, 1,3-butylene glycol di (meth) acrylate, 1, 4-butanediol di (meth) acrylate, EO-modified 1, 6-hexanediol di (meth) acrylate, ECH-modified 1, 6-hexanediol di (meth) acrylate, allyloxypolyethylene glycol acrylate, 1, 9-nonanediol di (meth) acrylate, EO-modified bisphenol A di (meth) acrylate, PO-modified bisphenol A di (meth) acrylate, modified bisphenol A di (meth) acrylate, EO-modified bisphenol F di (meth) acrylate, ECH-modified hexahydrophthalic acid diacrylate, hydroxypivalic acid neopentyl glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, EO-modified neopentyl glycol diacrylate, propylene oxide-modified (hereinbelow referred to as "PO-modified") neopentyl glycol diacrylate, caprolactone-modified hydroxy pivalate neopentyl glycol, stearic acid-modified pentaerythritol di (meth) acrylate, ECH-modified phthalic acid di (meth) acrylate, a poly (ethylene glycol-tetramethylene glycol) di (meth) acrylate, a poly (propylene glycol-tetramethylene glycol) di (meth) acrylate, a polyester di (meth) acrylate, a polyethylene glycol di (meth) acrylate, a polypropylene glycol di (meth) acrylate, ECH-modified propylene glycol di (meth) acrylate, silicone di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, dimethylol-tricyclodecane di (meth) acrylate, neopentyl glycol-modified trimethylolpropane di (meth) acrylate, tripropylene glycol di (meth) acrylate, EO-modified tripropylene glycol di (meth) acrylate, triglycerol di (meth) acrylate, dipropylene glycol di (meth) acrylate, divinylethylene-urea, and divinylpropylene-urea.

Among the above-enumerated bifunctional polymerizable unsaturatedmonomers, particularly, the monomers used appropriately in the embodiment of the pattern forming method in accordance with the present invention are neopentyl glycol di (meth) acrylate, 1, 9-nonanediol di (meth) acrylate, tripropylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, hydroxy pivalate neopentyl glycol di (meth) acrylate, and a polyethylene glycol di (meth) acrylate .

Examples of polyfunctional polymerizable unsaturated monomers having three or more ethylenically unsaturated bond-containing groups include ECH-modified glycerol tri (meth) acrylate, EO-modified glycerol tri (meth) acrylate, PO-modified glycerol tri (meth) acrylate, pentaerythritol triacrylate, EO-modified phosphoric acid triacrylate, trimethylolpropane tri (meth) acrylate, caprolactone-modified trimethylolpropane tri (meth) acrylate, EO-modified trimethylolpropane tri (meth) acrylate, PO-modified trimethylolpropane tri (meth) acrylate, tris (acryloxyethyl) isocyanurate, dipentaerythritol hexa (meth) acrylate, caprolactone-modified dipentaerythritol hexa (meth) acrylate, dipentaerythritol hydroxy penta (meth) acrylate, alkyl-modified dipentaerythritol penta (meth) acrylate, dipentaerythritol poly(meth) acrylate, alkyl-modified dipentaerythritol tri (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, pentaerythritol ethoxy tetra (meth) acrylate, and pentaerythritol tetra (meth) acrylate. Among the above-enumerated polyfunctional polymerizable unsaturated monomers having three or more ethylenically unsaturated bond-containing groups, particularly, the monomers used appropriately in the embodiment of the pattern forming method in accordance with the present invention are EO-modified glycerol tri (meth) acrylate, PO-modified glycerol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, EO-modified trimethylolpropane tri (meth) acrylate, PO-modified trimethylolpropane tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, pentaerythritol ethoxy tetra (meth) acrylate, and pentaerythritol tetra (meth) acrylate.

Examples of the compounds (epoxy compounds) having an oxirane ring include a polyglycidyl ester of a polybasic acid, a polyglycidyl ether of a polyhydric alcohol, a polyglycidyl ether of a polyoxyalkylene glycol, a polyglycidyl ether of an aromatic polyol, a hydrogenated compound of a polyglycidyl ether of an aromatic polyol, a urethane polyepoxy compound, and an epoxidated polybutadiene. Each of the above-enumerated compounds may be used alone, or two or more of the above-enumerated compounds may be used in combination.

Specific examples of the compounds (epoxy compounds) having an oxirane ring, which may be used appropriately in the embodiment of the pattern forming method in accordance with the present invention, include a bisphenol A diglycidyl ether, a bisphenol F diglycidyl ether, a bisphenol S diglycidyl ether, a brominated bisphenol A diglycidyl ether, a brominated bisphenol F diglycidyl ether, a brominated bisphenol S diglycidyl ether, a hydrogenated bisphenol A diglycidyl ether, a hydrogenated bisphenol F diglycidyl ether, a hydrogenatedbisphenol S diglycidyl ether, a 1, 4-butanediol diglycidyl ether, a 1, 6-hexanediol diglycidyl ether, a glycerol triglycidyl ether, a trimethylolpropane triglycidyl ether, a polyethylene glycol diglycidyl ether, a polypropylene glycol diglycidyl ether; a polyglycidyl ether of a polyether polyol, which is obtained by addition of at least one kind of an alkylene oxide to an aliphatic polyhydric alcohol, such as ethylene glycol, propylene glycol, or glycerol; a diglycidyl ester of an aliphatic long-chain dibasic acid; a monoglycidyl ether of an aliphatic higher alcohol; a monoglycidyl ether of phenol, cresol, butyl phenol, or a polyether alcohol obtained by addition of an alkylene oxide to phenol, cresol, or butyl phenol; and a glycidyl ester of a higher fatty acid.

Among the above-enumerated compounds having an oxirane ring, particularly, the preferable compounds are a bisphenol A diglycidyl ether, a bisphenol F diglycidyl ether, a hydrogenated bisphenol A diglycidyl ether, a hydrogenated bisphenol F diglycidyl ether, a 1, 4-butanediol diglycidyl ether, a 1, 6-hexanediol diglycidyl ether, a glycerol triglycidyl ether, a trimethylolpropane triglycidyl ether, a neopentyl glycol diglycidyl ether, a polyethylene glycol diglycidyl ether, and a polypropylene glycol diglycidyl ether.

Examples of commercially available compounds, which may be used appropriately as the glycidyl group-containing compounds include UVR-6216 (manufactured by Union Carbide Corporation) ; Glycidol, AOEX24, and Cyclomer A200 (each of which is manufactured by Daicel Chemical Industries, Ltd.; Epikote 828, Epikote 812, Epikote 1031, Epikote 872, and Epikote CT508 (each of which is manufactured by Yuka Shell Epoxy K.K.; and KRM-2400, KRM-2410, KRM-2408, KRM-2490, KRM-2720, and KR -2750 (each of which is manufactured by Asahi Denka Kogyo K.K.). Each of the above-enumerated compounds may be used alone, or two or more of the above-enumerated compounds may be used in combination.

No limitation is imposed upon techniques for producing the compounds having an oxirane ring. The compounds having an oxirane ring may be synthesized with reference to, for example, Fourth Edition Experimental Chemistry Course 20, Organic Synthesis II, 213~, 1992, published byMaruzen K.K. ; Ed. ByAlfred Hasfner, The Chemistry of heterocyclic compounds - Small Ring Heterocycles part 3 Oxiranes, John & Wiley and Sons, An Interscience Publication, New York, 1985; Yoshimura, Adhesion, Vol.29, No.12, 32, 1985; Yoshimura, Adhesion, Vol. 30, No. 5, 42, 1986; Yoshimura, Adhesion, Vol. 30, No. 7, 42, 1986; Japanese Unexamined Patent Publication No. 11 (1999) -100378, Japanese Patent No. 2906245, and Japanese Patent No. 2926262. As the other polymerizable monomer, which may be used in the embodiment of the pattern forming method in accordance with the present invention, a vinyl ether compoundmay be used in combination. The vinyl ether compound may be selected appropriately from known compounds. Examples of the vinyl ether compounds include 2-ethylhexyl vinyl ether, butanediol-1, 4-divinyl ether, diethylene glycol monovinyl ether, ethylene glycol divinyl ether, triethylene glycol divinyl ether, 1, 2-propanediol divinyl ether, 1, 3-propanediol divinyl ether, 1, 3-butanediol divinyl ether, 1, 4-butanediol divinyl ether, tetramethylene glycol divinyl ether, neopentyl glycol divinyl ether, trimethylolpropane trivinyl ether, trimethylolethane trivinyl ether, hexanediol divinyl ether, tetraethylene glycol divinyl ether, pentaerythritol divinyl ether, pentaerythritol trivinyl ether, pentaerythritol tetravinyl ether, sorbitol tetravinyl ether, sorbitol pentavinyl ether, ethylene glycol diethylene vinyl ether, triethylene glycol diethylene vinyl ether, ethylene glycol dipropylene vinyl ether, trimethylolpropane triethylene vinyl ether, trimethylolpropane diethylene vinyl ether, pentaerythritol diethylene vinyl ether, pentaerythritol triethylene vinyl ether, pentaerythritol tetraethylene vinyl ether, 1,1, 1-tris [4- (2-vinyloxyethoxy) phenyl] ethane, and bisphenol A divinyloxyethyl ether.

The vinyl ether compounds may be synthesized with the technique described in, for example, Stephen. C. Lapin, Polymers Paint Colour Journal, 179 (4237), 321 (1988). Specifically, the vinyl ether compounds maybe synthesized by a reaction of a polyhydric alcohol or a polyhydric phenol with acetylene, or a reaction of a polyhydric alcohol or a polyhydric phenol with a halogenated alkyl vinyl ether. Each of the vinyl ether compounds may be used alone, or two or more of the vinyl ether compounds maybe used in combination.

Also, as the other polymerizable monomer, a styrene derivative may be used. Examples of the styrene derivatives include styrene, p-methylstyrene, p-methoxystyrene, (¾-methy1styrene, p-methyl-p-methylstyrene, a-methylstyrene, p-methoxy-p-methylstyrene, and p-hydroxystyrene. In order for the mold releasability and the composition applicability to be enhanced, it is possible to use, in combination, a fluorine atom-containing compound, such as trifluoroethyl (meth) acrylate, pentafluoroethyl (meth) acrylate, (perfluorobutyl) ethyl (meth) acrylate, perfluorobutyl-hydroxypropyl (meth) acrylate,

(perfluorohexyl) ethyl (meth) acrylate, octafluoropentyl

(meth) acrylate, perfluorooctylethyl (meth) acrylate, and tetrafluoropropyl (meth) acrylate.

Further, as the other polymerizable monomer, a propenyl ether and a butenyl ether may be used. Examples of appropriate propenyl ethers and appropriate butenyl ethers include 1-dodecyl-l-propenyl ether, 1-dodecyl-l-butenyl ether, l-butenoxymethyl-2-norbornene, 1, 4-di (1-butenoxy) butane, 1, 10-di (1-butenoxy) decane, 1, 4-di (1-butenoxymethyl) cyclohexane, diethylene glycol di (1-butenyl) ether, 1, 2, 3-tri (1-butenoxy) propane, and propenyl ether propylene carbonate.

(Fluorine-Containing Polymerizable Surfactant)

In so far as the fluorine-containing polymerizable surfactant 22 is constituted of a polymerizable compound, such as a monomer or an oligomer, containing at least one functional group having a fluorine atom and at least one polymerizable functional group, no limitation is particularly imposed upon the fluorine-containing polymerizable surfactant 22. In order for good pattern formation to be enabled, the fluorine-containing polymerizable surfactant 22 should preferably be a compound having a steric configuration that is apt to undergo polymerization with the polymerizable compound 21.

In this embodiment, the fluorine-containing polymerizable surfactant 22, which constitutes a part of the resist pattern, should preferably have good resist characteristics, such as pattern formability, mold releasability after curing, and etching resistance.

By way of example, the content of the fluorine-containing polymerizable surfactant 22 in the resist composition 20 should preferably be selected within the range of 0.001 to 5 mass%, should more preferably be selected within the range of 0.002 to 4 mass%, and should most preferably be selected within the range of 0.005 to 3 mass%. In cases where at least two surfactants are used, the total content of the at least two surfactants should preferably be selected within the aforesaid range. In cases where the content of the fluorine-containing polymerizable surfactant 22 in the resist composition 20 is selected within the range of 0.001 to 5 mass%, good effect of uniformity of composition application is obtained, and there is little risk that deterioration of the mold transfer characteristics due to excess of the surfactant and deterioration of the aptitude for the etching at the etching stage after the imprinting will occur.

The fluorine-containing polymerizable surfactant 22 should preferablyhave the polymerizable group at a side chain, particularly at a terminal. Examples of the polymerizable functional groups include a radical polymerizable functional group, such as a (meth) acrylate group, a (meth) acrylamide group, a vinyl group, and an allyl group; and a cationic polymerizable functional group, such as an epoxy group, an oxetanyl group, or a vinyl ether group. The polymerizable functional group should preferably be a radical polymerizable functional group, and should more preferably be an ethylenically unsaturated bond group, such as a (meth) acrylate group.

The group, which has a fluorine atom, of the fluorine-containing polymerizable surfactant 22 should preferably be a fluorine-containing atom selected from a fluoroalkyl group and a fluoroalkylether group.

The fluoroalkyl group should preferably have a carbon number of at least 2, and should more preferably have a carbon number of at least 4. Though an upper limit of the carbon number is not specified particularly, the carbon number of the fluoroalkyl group should preferably be at most 20, should more preferably be at most 8, and should most preferably be at most 6. A fluoroalkyl group having a carbon number of 4 to 6 is most preferable. Examples of the preferable fluoroalkyl groups described above include a trifluoromethyl group, a pentafluoroethyl group, a heptafluoropropyl group, a hexafluoroisopropyl group, a nonafluorobutyl group, a tridecafluorohexyl group, and a heptadecafluorooctyl group.

In the embodiment of the pattern forming method in accordance with the present invention, the fluorine-containing polymerizable surfactant 22 should preferably be a polymerizable compound having a fluorine atom, which compoundhas a trifluoromethyl group structure. Specifically, at least one of the fluoroalkyl groups should preferably have the trifluoromethyl group structure. By the containing of the trifluoromethyl group structure, with a small adding amount (e.g., at most 10 mass%), the effects of the present invention are obtained, the surface energy becomes low, and the releasability is enhanced.

As in the cases of the fluoroalkyl group, the fluoroalkylether group should preferably have a trifluoromethyl group. A fluoroalkylether group containing a pefluoroethyleneoxy group or a perfluoropropyleneoxy group is preferable. It is preferable to employ a fluoroalkylether group having a fluoroalkylether unit that has a trifluoromethyl group, such as - (CF(CF₃) CF₂0) -, and/or having a trifluoromethyl group at a terminal of the fluoroalkylether group.

In the embodiment of the pattern forming method in accordance with the present invention, the fluorine-containing polymerizable surfactant 22 should particularlly preferably be a polymerizable monomer having at least two pieces of a fluorine-containing group, which is selected from the group consisting of a fluoroalkyl group and a fluoroalkylether group, at least two pieces of the fluorine-containing group being spaced apart from each other by a linking group having a carbon number of at least 2. Specifically, in cases where the polymerizable monomer has two pieces of the fluorine-containing group, the two pieces of the fluorine-containing group are spaced apart from each other by a linking group having a carbon number of at least 2. In cases where the polymerizable monomer has at least three pieces of the fluorine-containing group, two pieces of the fluorine-containing group are spaced apart from each other by a linking group having a carbon number of at least 2, and the other piece of the fluorine-containing group may have an arbitrary bond form. The linking group having a carbon number of at least 2 is the linking group having at least two carbon atoms that are not substituted by a fluorine atom.

From the same point of view, a polymerizable monomer containing at least three trifluoromethyl group structures is preferable. The polymerizable monomer should preferably contain three to nine trifluoromethyl group structures, and should more preferably contain four to six trifluoromethyl group structures. As the compound containing at least three trifluoromethyl group structures, it is preferable to employ a compound having a branched fluoroalkyl group having at least two trifluoromethyl groups in one fluorine-containing group, e.g. a fluoroalkyl group, such as a -CH(CF₃)₂ group, a -C(CF₃)₃ group, or a -CCH₃(CF₃)2CH₃ group.

The fluoroalkylether group should preferably have a trifluoromethyl group. A fluoroalkylether group containing a pefluoroethyleneoxy group or a perfluoropropyleneoxy group is preferable. It is preferable to employ a fluoroalkylether group having a fluoroalkylether unit that has a trifluoromethyl group, such as - (CF(CF₃)CF₂0) and/or having a trifluoromethyl group at a terminal of the fluoroalkylether group.

A functional group contained in the linking group having a carbon number of at least 2 may be, for example, an alkylene group, an ester group, a sulfide group, or an arylene group. The functional group contained in the linking group having a carbon number of at least 2 shouldpreferablyhave at least an ester group and/or a sulfide group.

The linking group having a carbon number of at least 2 should preferably be an alkylene group, an ester group, a sulfide group, an arylene group, or a combination of two or more of the above-enumerated groups.

The above-enumerated groups may have a substituent group without departing from the spirit and scope of the present invention. The total number of the fluorine atoms, which the fluorine-containing polymerizable surfactant 22 have, should preferably be selected from the range of 6 to 60 per molecule, should more preferably be selected from the range of 9 to 40 per molecule, and should most preferably be selected from the range of 12 to 40 per molecule.

The fluorine-containing polymerizable surfactant 22 should preferably be a polymerizable compound having a fluorine atom, in which the fluorine content defined below is selected from the range of 20% to 60%. In cases where the fluorine-containing polymerizable surfactant 22 is a polymerizable monomer, the fluorine content of the polymerizable monomer should more preferably be selected from the range of 30% to 60%, and should most preferably be selected from the range of 35% to 60%. In cases where the fluorine-containing polymerizable surfactant 22 is an oligomer having a polymerizable group, the fluorine content of the oligomer should more preferably be selected from the range of 20% to 50%, and should most preferably be selected from the range of 20% to 40%. By the selection of the fluorine content within the appropriate range, the compatibility with the other ingredients becomes excellent, the mold staining is suppressed, and the releasability is enhanced at the same time. Also, the repeated pattern formability, which is an effect of the embodiment of the pattern forming method in accordance with the present invention, is enhanced. As in the cases of the polymerizable compound described above, the fluorine content is represented by formula (CI) shown below.

Fluorine content =

lOO

molecular weight of po!ymerizabl e co mpound

(CI)

One preferable form of the fluorine-containing polymerizable surfactant 22 is a compound (monomer) , which has a partial structure that is represented by general formula (Il-a) shown below, as a preferable example of the group having a fluorine atom. By the employment of the compound having the partial structure described above, the pattern formability is kept excellent even in the cases of the repeated pattern transfer, and the stability of the composition with the passage of time becomes good.

-CH2CH2-C_nF2n+i

(II-a) wherein n represents an integral number of 1 to 8, preferably an integral number of 4 to 6.

A different preferable form of the fluorine-containing polymerizable surfactant 22 is a compound, which has a partial structure that is represented by general formula (Il-b) shown below, as a preferable example of the group having a fluorine atom. Also, the fluorine-containing polymerizable surfactant 22 may be a compound, which has both the partial structure that is represented by general formula (II-a) and the partial structure that is represented by general formula (Il-b) .

(Il-b) wherein L¹ represents a single bond or an alkylene group having a carbon number of 1 to 8, L² represents an alkylene group having a carbon number of 1 to 8, each of ml and m2 represents a number of 0 or 1, with the proviso that at least either one of ml and m2 represents a number of 1, m3 represents an integral number of 1 to 3, and p represents an integral number of 1 to 8, with the proviso that, in cases where m3 represents an integral number of at least 2, the at least two -C_pF2p+i moieties may be identical or different. In general formula (Il-b) , each of L¹ and L² should preferably be an alkylene group having a carbon number of 1 to 4. Also, the alkylene group may have a substituent group without departing from the spirit and scope of the present invention. Further, m3 should preferably represent a number of 2 or 3. Furthermore, p should preferably represent an integral number of 4 to 6.

The fluorine-containing polymerizable surfactant 22 should preferably be a polymerizable monomer that is represented by general formula (II-c) shown below.

(II-c) wherein R¹ represents a hydrogen atom, an alkyl group, a halogen atom, or a cyano group, A represents a (al+a2) -valent linking group, al represents an integral number of 1 to 6, a2 represents an integral number of 2 to 6, each of R² and R³ represents an alkylene group having a carbon number of 1 to 8, each of ml and rti2 represents a number of 0 or 1, with the proviso that at least either one of ml and m2 represents a number of 1, m3 represents an integral number of 1 to 3, each of m4 and rti5 represents a number of 0 or 1, with the proviso that at least either one of m4 and m5 represents a number of 1, and with the proviso that, in cases where both of ml and m2 represent a number of 1, m4 represents a number of 1, andn represents an integral number of 1 to 8.

In general formula (II-c) , R¹ should preferably represent a hydrogen atom or an alkyl group, should more preferably represent a hydrogen atom or a methyl group, and should more preferably represent a hydrogen atom.

Also, in general formula (II-c) , A should preferably represent a linking group having an alkylene group and/or an arylene group and may further contain a linking group containing a heteroatom. Examples of the linking groups containing a heteroatom include -0-, -C (=0) 0-, -S-, and -C (=0) - . The linking group may have a substituent group without departing from the spirit and scope of the present invention. However, it is preferable that the linking group does not have a substituent group. A should preferably have a carbon number of 2 to 50, and should more preferably have a carbon number of 4 to 15.

Further, in general formula (II-c), al should preferably represent an integral number of 1 to 3, and should more preferably represent a number of 1 or 2. Furthermore, a2 should preferably represent a number of 2 or 3, and should more preferably represent a number of 2.

In cases where al represents an integral number of at least 2, the corresponding linking groups representedbyAmaybe identical or different.

In cases where a2 represents an integral number of at least 2, the corresponding alkylene groups represented by R², the corresponding alkylene groups represented by R³, the corresponding numbers represented by ml, the corresponding numbers represented bym2, the corresponding numbers representedbym3, the corresponding numbers represented by m4, the corresponding numbers represented bym5, and the correspondingnumbers representedbynmaybe identical or different.

The molecular weight of the polymerizable monomer, which is employed as the fluorine-containing polymerizable surfactant 22 in the embodiment of the pattern forming method in accordance with the present invention, should preferably be selected within the range of 500 to 2,000. Also, the viscosity of the polymerizable monomer should preferably be selected within the range of 600 to 1,500, and should more preferably be selected within the range of 600 to 1,200.

Specific examples of the polymerizable monomers, which are employed as the fluorine-containing polymerizable surfactant 22, will be shown below. However, the polymerizable monomer is not limited to the specific examples shown below. In the formulae shown below, R¹ represents a hydrogen atom, an alkyl group, a halogen atom, or a cyano group.

Also, other examples of the polymerizable monomers, which are employed as the fluorine-containing polymerizable surfactant 22, include monofunctional polymerizable compounds having a fluorine atom, such as trifluoroethyl (meth) acrylate, pentafluoroethyl (meth) acrylate, (perfluorobutyl) ethyl (meth) acrylate, perfluorobutyl-hydroxypropyl (meth) acrylate,

(perfluorohexyl) ethyl (meth) acrylate, octafluoropentyl

(meth) acrylate, perfluorooctylethyl (meth) acrylate, tetrafluoropropyl (meth) acrylate, and hexafluoropropyl (meth) acrylate . Also, examples of preferable polymerizable compounds having a fluorine atom include polyfunctional polymerizable compounds having at least two polymerizable functional groups having di (meth) acrylate having a fluoroalkylene group, such as 2,2,3,3,4,4-hexafluoropentane di (meth) acrylate or 2, 2, 3, 3, 4, 4, 5, 5-octafluorohexane di (meth) acrylate.

Further, it is possible to use appropriately a compound having at least two fluorine-containing groups, e.g. a fluoroalkyl group or a fluoroalkylether group, in one molecule.

In cases where the polymerizable compound having a fluorine atom is an oligomer, or the like, the oligomer, or the like, should preferably contain the aforesaid polymerizable monomer as the repeating unit.

Furthermore, as the surfactant, it is possible to use compounds described in paragraphs [0018] to [0048] of Japanese Unexamined Patent Publication No. 2006-114882, and fluorine-containing polymerizable compounds described in paragraphs [0027] to [0035] of Japanese Unexamined Patent Publication No. 2008-95037.

Synthesis examples of the fluorine-containing polymerizable surfactant 22 used in the embodiment of the pattern forming method in accordance with the present invention will be described hereinbelow as specific examples.

[Synthesis Example 1]

(Synthesis of Fluorine-Containing Polymerizable Monomer Ax-1) Firstly, 45ml of ethanol and 5ml of water were added to 2g of thioerythritol, and the resulting mixture was subjected to dissolution. Thereafter, l.lg of sodium hydroxide was added to the resulting solution, and the resulting mixture was stirred at the room temperature for 30 minutes. Thereafter, 15.4g of perfluorohexylethyl iodide was added to the mixture, and the thus obtained mixture was allowed to undergo reaction at a temperature of 90°C for seven hours. Ethyl acetate was added to the reaction mixture, and the organic phase was washed with water and then with saturated saline solution. The organic phase was then dried and concentrated, and a compound (Ax-la) was thus obtained.

Thereafter, 6.7g of the compound (Ax-la) was dissolved in 80ml of acetone, and 3.2g of triethylamine was added to the resulting solution. Further, 2.5g of acrylic acid chloride was added dropwise to the resulting mixture under ice-cooling. After the dropwise addition, the resulting mixture was allowed to undergo reaction at the room temperature for 20 hours. Thereafter, 50ml of water was added to the reaction liquid, and the reaction liquid was subjected to extraction with ethyl acetate. The organic phase was washed with an aqueous IN hydrochloric acid solution, a saturated aqueous sodium hydrogencarbonate solution, and a saturated saline solution. The organic phase was then dried and concentrated, and a crude product was thus obtained. The crude product was purified with column chromatography, and 2.8g of a polymerizable monomer Ax-1 was thereby obtained.

1H-NMR (CDCla) : 52.2-2.5 (m, 4H) , 52.7-3.0 (m, 8H),.55.4 (m, 2H) , 55.95 (d, 2H), 56.1 (dd, 2H) , 56.45 (d, 2H)

[Synthesis Example 2]

(Synthesis of Polymerizable Monomer Ax-2)

Firstly, 2g of dithioerythritol was dissolved in 20ml of ethyl acetate, and 0.2g of triethylamine and 11.4g of perfluorohexylethyl acrylate were added to the resulting solution, and the thus obtained mixture was allowed to undergo reaction at the room temperature for four hours. Thereafter, 4.0g of triethylamine and 20ml of ethyl acetate were added to the reaction liquid, and 2.9g of acrylic acid chloride was added dropwise to the resulting mixture under ice-cooling. After the dropwise addition, the resultingmixture was allowed to undergo reaction at the room temperature for 20 hours. Thereafter, 50ml of water was added to the reaction liquid, and the resulting mixture was stirred. The organic phase was washed with an aqueous IN hydrochloric acid solution, a saturated aqueous sodium hydrogencarbonate solution, and a saturated saline solution. The organic phase was then dried and concentrated, and a crude product was thus obtained. The crude product was purified with column chromatography, and 3g of a polymerizable monomer Ax-2 was thereby obtained.

1H-NMR (CDC1₃) : 52.4-3.0 (m, 16H) , 54.4 (t, 4H) , 55.4 (m, 2H) , 55.9

(d, 2H), 56.1 (dd, 2H), 56.45 (d, 2H)

[Synthesis Example 3]

Polymerizable monomers (Ax-3) to (Ax-7) were synthesized by use of the techniques identical with the techniques of Synthesis Examples 1 and 2 described above.

(Ax-3)

52.3-2.6 (m, 4H) , 52.8-3.0 (m, 6H) , 53.1 (m, 1H) , 54.4 (m, 2H) , 55.9 (d, 2H), 56.1 (dd, 2H), 56.45 (d, 2H)

(Ax-4)

52.2-2.6 (m, 4H) , 52.7-3.0 (m, 8H) , 55.4 (m, 2H) , 55.95 (d, 2H) , 56.1

(dd, 2H), 56.45 (d, 2H)

(Ax-5)

52.8-3.0 (m, 12H) , 55.4 (m, 2H) , 55.8 (m, 2H) , 55.9 (d, 2H) , 56.1 (dd, 2H), 56.45 (d, 2H) (Ax-6)

62.8-3.0 (m, 12H) , 63.1 (m, 1H) , 64.4 (m, 2H) , 65.8 (m, 2H) , 65.9

(d, 1H), 66.1 (dd, 1H), 66.45 (d, 1H)

(Ax-7)

62.3-2.6 (m, 4H) , 62.8-3.0 (m, 6H) , 63.1 (m, 1H) , 64.4 (m, 2H) , 65.9 (d, 2H), 66.1 (dd, 2H) , 66.45 (d, 2H)

(Ax-5) (Ax-6) (Ax-7) (Polymerization Initiator I)

The polymerization initiator I may be selected from a wide variety of compounds, which are activated by the light LI used at the time of the curing of the resist composition 20 and generate active species for initiating the polymerization of the polymerizable compound contained in the resist composition 20. As the polymerization initiator I, a radical polymerization initiator is preferable. Also, in the embodiment of the pattern forming method in accordance with the present invention, a plurality of kinds of the polymerization initiators I may be used in combination.

From the view points of the curing sensitivity and the absorption characteristics, the polymerization initiator I should preferably be an acylphosphine oxide type compound or an oxime ester type compound. By way of example, compounds described in paragraph [0091] of Japanese Unexamined Patent Publication No. 2008-105414 may be employed preferably.

The content of the polymerization initiator I in the entire composition other than solvents may be selected within the range of, for example, 0.01 to 15 mass%, should preferably be selected within the range of 0.1 to 12 mass%, and should more preferably be selected within the range of 0.2 to 7 mass%. In cases where two or more kinds of the polymerization initiators are used, the total amount of the polymerization initiators may be selected within the range described above.

In cases where the content of the polymerization initiator is at least 0.01 mass%, there is a preferable tendency for sensitivity (rapid curability) , resolution characteristics, line edge roughness characteristics, and coating film strength to be enhanced. In cases where the content of the polymerization initiator is at most 15 mass%, there is a preferable tendency for transparency, coloring characteristics, and processing characteristics to be enhanced.

As for ink et compositions and compositions for liquid crystal display color filters, which contain dyes and/or pigments, various studies have heretofore been made with respect to the preferable content of the polymerization initiator. However, as for curable compositions for photoimprints, such as the curable compositions for imprints, which contain dyes and/or pigments, nothing has heretofore been made with respect to the preferable content of the polymerization initiator. Specifically, in the systems containing the dyes and/or pigments, the initiator often acts as a radical trapping agent and adversely affects the polymerizability and the sensitivity. In the aforesaid use applications, the adding amount of the polymerization initiator is optimized with the aforesaid problems being taken into consideration. In the cases of the resist composition 20, the dyes and/or pigments are not the essential ingredients, and it may often occur that the optimum range of the content of the polymerization initiator varies from the optimum ranges in the fields of the inkjet compositions and the compositions for liquid crystal display color filters.

From the view points of the curing sensitivity and the absorption characteristics, the radical polymerization initiator used in the embodiment of the pattern forming method in accordance with the present invention should preferably be an acylphosphine type compound or an oxime ester type compound. By way of example, as the radical polymerization initiator used in the embodiment of the pattern forming method in accordance with the present invention, a commercially available initiator may be used. By way of example, the compounds described in paragraph [0091] of Japanese Unexamined Patent Publication No. 2008-105414 may be employed preferably.

Examples of the light LI include the light having wavelengths within the ultraviolet range, the near-ultraviolet range, the far-ultraviolet range, the visible range, or the infrared range; an electromagnetic wave; and radiation. Examples of the radiation include a microwave, an electron beam, EUV, and X-rays. It is also possible to employ a laser beam, such as a 248nm excimer laser beam, a 193nm excimer laser beam, or a 172nm excimer laser beam. The light may be monochromatic light (single wavelength light) , which has passed through an optical filter, or maybe light (mixed light) having different wavelengths. As for exposure, multiple exposure is possible. For the purposes of enhancing the film strength and the etching resistance, it is possible to perform entire surface exposure after the pattern formation.

It is necessary for the polymerization initiator I to be selected appropriately with respect to the wavelength of the light produced by a light source used. The polymerization initiator I should preferably have the characteristics such that the polymerization initiator I does not produce a gas during the mold pressing and the exposure. If a gas is generated, the problems occur in that the mold must be washed frequently due to the mold staining, and in that the transfer pattern accuracy becomes bad due to deformation of the resist composition 20 within the mold.

The resist composition 20 should preferably be such that the polymerizable monomer contained is the radical polymerizable monomer, and such that the polymerization initiator I contained is the radical polymerization initiator which generates a radical by the irradiation with light.

(Other Ingredients)

As described above, besides the polymerizable compound 21, the fluorine-containing polymerizable surfactant 22, and the polymerization initiator I, the resist composition 20 used in the en±>odiment of the pattern forming method in accordance with the present invention may also contain other ingredients, such as a surfactant, an antioxidant, a solvent, and a polymer ingredient, in accordance with various purposes and within the range such that the effects of the pattern forming method in accordance with the present invention are not lost. The other ingredients will be briefly described hereinbelow.

-Antioxidant-

The resist composition 20 may contain a known antioxidant. The content of the antioxidant with respect to the polymerizable monomer may be selected within the range of, for example, 0.01 to 10 mass%, and should preferably be selected within the range of 0.2 to 5 mass%. In cases where two or more kinds of the antioxidants are used, the total amount of the antioxidants may be selected within the range described above.

The antioxidant suppresses color fading due to heat or light irradiation, and the color fading due to various oxidizing gases, such as ozone, active oxygen, NO_x, and SO_x (where x represents an integral number) . Particularly, in the embodiment of the pattern formingmethod in accordance with the present invention, the addition of the antioxidant yields the advantages in that coloring of the cured film is prevented, and in that a decrease in film thickness due to decomposition is suppressed. Examples of the antioxidants include a hydrazide, a hindered amine type antioxidant, a nitrogen-containing heterocyclic mercapto type compound, a thioether type antioxidant, a hindered phenol type antioxidant, an ascorbic acid, zinc sulfate, a thiocyanate, a thiourea derivative, a saccharide, a nitrite, a sulfite, a thiosulfate, and a hydroxylamine derivative. Particularly, from the viewpoints of the prevention of the coloring of the cured film and the decrease in film thickness, a hindered phenol type antioxidant and a thioether type antioxidant are preferable.

Examples of commercially available antioxidants include Irganox 1010, Irganox 1035, Irganox 1076, and Irganox 1222 (each of which is manufactured by Chiba-Geigy Japan) ; Antigene P, Antigene 3C, Antigene FR, Sumilizer S, and Sumilizer GA80 (each of which is manufactured by Sumitomo Chemical Co., Ltd.); Adekastab AO70, Adekastab AO80, and Adekastab AO503 (each of which is manufactured by Adeka Co., Ltd.) . Each of the above-enumerated antioxidants may be used alone, or two or more of the antioxidants may be used in combination.

-Polymerization Inhibitor-

The resist composition should preferably contain a small amount of a polymerization inhibitor. The content of the polymerization inhibitor with respect to the entire polymerizable monomer should preferably be selected within the range of 0.001 to 1 mass%, should more preferably be selected within the range of 0.005 to 0.5 mass%, and should most preferably be selected within the range of 0.008 to 0.05 mass%. By the containing of an appropriate amount of the polymerization inhibitor, the alteration in viscosity with the passage of time is suppressed, while a high curing sensitivity is being kept.

-Solvent-

If necessary, the resist composition 20 may contain an arbitrary solvent. A preferable solvent is a solvent having a boiling temperature of 80°C to 200°C at the normal pressures. The solvent may be selected from various solvents which can dissolve the composition. The solvent should preferably be a solvent having at least one of the members selected from the group consisting of an ester structure, a ketone structure, a hydroxyl group, and an ether structure. Specifically, a preferable solvent is a single or mixed solvent selected from the group consisting of propylene glycol monomethyl ether acetate, cyclohexanone, 2-heptanone, gamma-butyrolactone, propylene glycol monomethyl ether, and ethyl lactate. From the view point of the composition application uniformity, a solvent containing propylene glycol monomethyl ether acetate is most preferable.

The content of the solvent in the resist composition 20 is adjusted at an optimum value in accordance with the viscosity of the ingredients other than the solvent, the composition applicability, and the desired film thickness. From the view point of the improvement of the composition applicability, the content of the solvent in the entire composition should preferably be selectedwithin the range of 0 to 99 mass%, and shouldmore preferably be selected within the range of 0 to 97 mass% . Particularly, in cases where a pattern having a film thickness of at most 500nm is to be formed, the content of the solvent in the entire composition should preferably be selected within the range of 20 to 99 mass%, should more preferably be selected within the range of 40 to 99 mass%, and shouldmost preferablybe selected within the range of 70 to 98 mass%. -Polymer Ingredient-

In order for the crosslink density to be enhanced even further, the resist composition 20 may contain a polyfunctional oligomer, which has a molecular weight larger than the molecular weight of the other polyfunctional polymerizable monomer described above, in a proportion within the range for accomplishing the object of the present invention. Examples of the polyfunctional oligomers having the radical photopolymerizability include acrylate oligomers, such as a polyester acrylate, urethane acrylate, a polyether acrylate, and epoxy acrylate. The adding amount of the oligomer ingredient with respect to the ingredients of the composition other than the solvent should preferably be selected within the range of 0 to 30 mass%, should more preferably be selected within the range of 0 to 20mass%, shouldparticularlypreferablybe selectedwithin the range of 0 to 10 mass%, and should most preferably be selected within the range of 0 to 5 mass%.

From the view points of the improvements of the dry etching resistance, the aptitude for imprinting, and the curability, the resist composition 20 may contain a polymer ingredient. As the polymer ingredient, a polymer having a polymerizable functional group at a side chain is preferable. From the view point of the compatibility with the polymerizable monomer, a weight-average molecular weight of the polymer ingredient should preferably be selected within the range of 2,000 to 100,000, and should more preferably be selected within the range of 5,000 to 50,000.

The adding amount of the polymer ingredient with respect to the ingredients of the composition other than the solvent should preferably be selected within the range of 0 to 30 mass%, should more preferably be selected within the range of 0 to 20 mass%, should particularlypreferablybe selectedwithin the range of 0 to 10 mass%, and should most preferably be at most 2 mass%. From the view point of the pattern formability, in the resist composition 20, the content of the polymer ingredient, which has a molecular weight of at least 2,000, with respect to the ingredients other than the solvent should preferably be at most 30 mass%. The content of the resin ingredient should preferably be as small as possible. It is preferable that, besides the surfactant and trace amounts of additives, the resist composition 20 does not contain the resin ingredient.

Besides the ingredients described above, if necessary, the resist composition 20 may contain a release agent, a silane coupling agent, a ultraviolet absorber, light stabilizer, an antiaging agent, a plasticizer, an adhesion promoter, a thermal polymerization initiator, a colorant, elastomer particles, a photoacid multiplier, a photobase generator, a basic compound, a flow adjusting agent, a defoaming agent, and a dispersant.

The resist composition 20 may be prepared by mixing the aforesaid ingredients. Also, after the ingredients have been mixed together, the resulting mixture may be filtered by use of a filter having a pore diameter of 0.003um to 5. Oum, and the resist composition 20 may thus be prepared in the form of a solution. In the cases of the curable composition for photoimprints, ordinarily, the mixing and the dissolution are performed at a temperature selected within the range of 0°C to 100°C. The filtration may be performed at a plurality of stages, ormaybe repeated a plurality of times. Further, an obtained filtrate maybe subjected to re-filtration. The material of the filter used for the filtration is not limited particularly andmaybe selected from a polyethylene resin, a polypropylene resin, a fluorine resin, and a nylon resin.

In the resist composition 20, the viscosity of the ingredients other than the solvent at a temperature of 25°C should preferably be selected within the range of 1 to lOOmPa-s, should more preferably be selected within the range of 3 to 50mPa-s, and should most preferably be selected within the range of 5 to 30mPa*s. By the selection of the viscosity within the appropriate range, the pattern rectangularity is enhanced, and the residual layer thickness is kept thin.

[Process for Producing Pattern Substrate]

The resist layer 40 having been pattern-formed on the substrate 10 with the aforesaid method may be used as a mask for the patterning of the substrate 10 with the lithography technique. In this ei±>ociiment, as illustrated at F in Figure 1, protrusion and recess pattern processing is performed on the surface 10S of the substrate 10 by use of the resist pattern 1, which has been formed on the substrate 10, as the mask.

No limitation is imposed upon the technique for processing the substrate 10. It is preferable to employ a technique capable of processing in a direction approximately normal to the substrate surface 10S and with a high pattern accuracy. Examples of the preferable processing techniques include the dry etching technique and an ion milling technique.

After the recesses having a desired depth have been formed on the substrate 10 as illustrated at G in Figure 1, the resist layer 40 remaining on the substrate 10 is removed as illustrated at H in Figure 1, and a pattern substrate 2 is thus obtained. No limitation is imposed upon the technique for removing the resist layer 40. It is preferable to employ an anisotropic etching technique with oxygen plasma.

With the embodiment of the pattern forming method in accordance with the present invention, the resist layer 20m is formed on the substrate 10, the resist layer 20m comprising the resist composition 20, which is arranged as the plurality of the discrete droplets 20, the resist composition 20 containing the polymerizable compound 21, the polymerization initiator I which is activated by the light LI, and the fluorine-containing polymerizable surfactant 22. With the resist layer 20m, wherein the fluorine content in the resist composition 20 is low, the viscosity of the resist composition 20 and the etching resistance of the resist layer 40 after being cured are kept appropriately. Also, with the resist layer 20m, in which the fluorine-containing polymerizable surfactant 22 is contained, the pattern formation failure and deterioration of the mold 30 due to uneven distribution, adhesion, and accumulation of the surfactant are not promoted, and the releasability of the mold 30 is kept good.

Therefore, with the embodiment of the pattern forming method in accordance with the present invention, the pattern formation with the imprinting technique is performed such that the high-accuracy patterning is performed in the nano-order pattern formation, and such that the mass productivity and the etching resistance are good.

Also, with the embodiment of the process for producing a pattern substrate in accordance with the present invention, wherein the substrate 10 is processed with the lithography technique by use of the resist pattern 1, which has been prepared by the embodiment of the pattern forming method in accordance with the present invention, as the mask, the pattern substrate 2 having been subjected to patterning at a high accuracy is produced.

Examples

The present invention will further be illustrated by the following non-limitative examples.

Example 1

An Si substrate was prepared, and the processing surface was cleaned with a UV cleaner (cleaning time: one minute). Thereafter, an adhesion agent layer was formed on the substrate under conditions, such that the thickness of the adhesion agent layer might become equal to O.lnm, with the spin coating technique by use of a surface treatment liquid, which was prepared by mixing O.lg of 3-acryloxypropyltrimethoxysilane (KBM-5103, manufactured by Shin-Etsu Chemical Co., Ltd.) acting as a silane coupling agent and lOg of propylene glycol monomethyl ether acetate (PG EA) acting as an organic solvent. Further, the substrate was subjected to annealing treatment under the conditions of a temperature of 120°C and a period of time of five minutes.

Thereafter, a resist composition R1A was jetted out in accordance with a mold pattern shape by use of the inkjet technique and under inkjet conditions described below. A resist layer was thus formed on the substrate.

«Resist Composition R1A»

- Polymerizable compound: (1, 4-Diacryloyloxymethylbenzene,

and 2' -naphthylmethyl acrylate) 49g each

■ Fluorine-containing polymerizable surfactant: (Ax-2) l.Og

- Polymerization initiator: (Ethyl-2, 4, 6-triethylbenzoinphenyl phosphinate) (Irgacure 379, manufactured by BASF) l.Og

(Inkjet Conditions)

Printer: DMP2831 (manufactured by FUJIFILM Dimatix, Inc.) Head: Special-purpose head having lOpl nozzles

Jetting-out conditions: A wave form adjustment was made so as to obtain a 6pl jetting-out amount.

Drawing pattern: Droplets (corresponding to 20m) were arranged at intersection points of a 450um-pitch lattice-like pattern. <Imprinting Stage>

A quartz mold structural body having a protrusion and recess pattern formed on a surface of a 2.5-inch disc was prepared. The protrusion and recess pattern comprised concentric circular stripes arranged at 90nmpitches (protrusions: 50nmwidth, depth 65nm, taper angle 83°) in the following four radial direction areas: (1) 22mm~32mm (10mm width band) , (2) 19mm~18mm ( lmm width band) , (3) 14.9mm~15.0mm ( lmm width band) , (4) 12.01mm~12.00mm (0.01mm width band) . Release treatment was performed on the surface provided with the protrusion and recess pattern by use of a fluorine type anti-staining coating agent (Optool DSX, manufactured by Daikin Industries, Ltd. ) .

The protrusion and recess pattern surface of the aforesaid mold structural body was pushed against the Si substrate, on which the resist layer had been formed, under a helium atmosphere within a chamber. Thereafter, a pressure was applied uniformly to the resist layer with the entire area of the mold structural body for 60 seconds under the conditions of the room temperature and 10 atm, and the protrusion and recess pattern having been formed on the mold structural body was transferred to the resist layer. In this state, UV light (having a wavelength of 365nm) was irradiated at 300mJ/cm² from the mold structural body side. The resist was thus cured, and the patterned shape was fixed. Thereafter, the mold structural body was released over a period of time of one second. In this manner, a pattern-formed body having the resist layer, to which the protrusion and recess pattern had been transferred, was prepared. <Pattern Forming Stage>

Dry etching was performed on the pattern-formed body having the resist layer, to which the protrusion and recess pattern had been transferred, by use of the imprinting resist layer, to which the protrusion and recess pattern had been transferred, as the mask. The dry etching was performed on the substrate, which was cooled at 10°C from the rear surface, by use of an argon ion milling technique (ICP etching apparatus E-550, manufactured by ULVAC, Inc.) . The protrusion and recess pattern in accordance with the protrusion and recess pattern having been formed in the resist layer was thus formed on the substrate.

Thereafter, oxygen ashing treatment was performed on the surface of the pattern-formed body, on which the protrusion and recess pattern hadbeen formed. Further, UV treatment was performed. The resist layer remaining after the substrate processing was thus removed.

Comparative Example 1

Mask pattern formation and substrate processing were performed in the same manner as that in Example 1, except that a resist layer was formed on the substrate by preparing a resist composition RIB with the formulation shownbelow, applying the resist composition onto the substrate with a spin coating technique such that the thickness after baking might become equal to 40nm, and further performing baking treatment (at a temperature of 60°C for one minute) .

«Resist Composition R1B»

• Polymerizable compound: (1, 4-Diacryloyloxymethylbenzene,

and 2' -naphthylmethyl acrylate) 20g each

• Fluorine-containing polymerizable surfactant: (Ax-2) l.Og

• Polymerization initiator: (Ethyl-2, 4, 6-triethylbenzoinphenyl phosphinate) (Irgacure 379, manufactured by BASF) 0.8g

- Organic solvent (PGMEA: solid material concentration 4%) 959. Og

Comparative Example 2

Mask pattern formation and. substrate processing were performed in the same manner as that in Comparative Example 1, except that a fluorine-containing surfactant having no polymerizability (PF656, manufactured by PolyFox K.K.) was used as the surfactant.

Comparative Example 3

Mask pattern formation and substrate processing were performed in the same manner as that in Comparative Example 1, except that the surfactant was not added to the resist composition.

Comparative Example 4

Mask pattern formation and substrate processing were performed in the same manner as that in Example 1, except that a fluorine-containing surfactant having no polymerizability (PF656, manufactured by PolyFox K.K.) was used as the surfactant.

Comparative Example 5

Mask pattern formation and substrate processing were performed in the same manner as that in Example 1, except that the surfactant was not added to the resist composition.

Example 2

Mask pattern formation and substrate processing were performed in the same manner as that in Example 1, except that an aliphatic polyfunctional monomer was used as the polymerizable compound contained in the resist composition.

Ingredients of a resist composition R2 used were as shown below.

«Resist Composition R2»

• Polymerizable compound: (TPGDA: tripropylene glycol

diacrylate) (Aronix M220, manufactured by Toagosei Co., Ltd.) 98. Og

• Fluorine-containing polymerizable surfactant: (Ax-2) l.Og - Polymerization initiator: (Ethyl-2, , 6-triethylbenzoinphenyl phosphinate) (Irgacure 379, manufactured by BASF) l.Og

Comparative Example 6

Mask pattern formation and substrate processing were performed in the same manner as that in Example 2, except that a fluorine-containing surfactant having no polymerizability (PF656, manufactured by PolyFox K.K.) was used as the surfactant.

Comparative Example 7

Mask pattern formation and substrate processing were performed in the same manner as that in Example 2, except that the surfactant was not added to the resist composition.

Comparative Example 8

Mask pattern formation and substrate processing were performed in the same manner as that in Example 2, except that a fluorine-containing resin (a polymer of a fluorene prepolymer M01 described below, polymerization degree: 200~400) was used as the polymerizable compound contained in the resist composition, and except that the surfactant was not used.

(Fluorene Prepolymer)

A monomer having an isocyanate group was obtained by introducing 58g of isophorone diisocyanate, 39g of 2-hydroxyethyl acrylate, 0.02g of p-methoxy phenol, and 0.005g of dibutyltin dilaurate into a 500ml glass reactor, and sufficiently stirring the resultingmixture, while the temperature within the reactor was being adjusted at a value of at most 70°C. Thereafter, 161g of a fluoro polymer having a hydroxyl group (Lumiflon LF910LM, manufactured by Asahi Glass Co., Ltd.) was added to the reactor, and the resulting mixture was stirred sufficiently with the temperature being kept within the range of 80°C to 90°C. Also, 0.02g of dibutyltin dilaurate was added. An obtained reaction product was purified, and a fluorene prepolymer M01 (fluorine content: 41 wt%) was thus obtained.

Comparative Example 9

Mask pattern formation and substrate processing were performed in the same manner as that in Example 2, except that a fluorine-containing resin (the fluorene prepolymer M01) described above) was used as the polymerizable compound contained in the resist composition, and except that the surfactant (the fluorine-containing polymerizable compound) was not used.

As for each of Examples 1 and 2 and Comparative Examples 1 to 9, evaluation was made as described below with respect to the performance at the time of resist application, the mold releasability, the resist pattern shape and the residual layer thickness, the deterioration of characteristics after repeated pattern formation (50 times) , and the shape and the quality during substrate processing. The evaluation results and liquid physical properties are shown in Table 1.

«Performance at the Time of Resist Application»

Evaluation of the film formability was made with the criterion described below.

- Spin coating technique

Film formation was possible: O

Film formation was impossible: *

• Inkjet technique

Jetting-out performance was good

(no jetting-out non-performance, shift in position of droplet deposition≤25um) : O

Jetting-out performance was not good, but pattern formation was possible

(no jetting-out non-performance,

100um>shift in position of droplet deposition>25um) : Δ Jetting-out non-performance (at most 5% of nozzles) , (shift in position of droplet deposition≥100um) : * Jetting-out non-performance (at least 5% of nozzles) : ^χχ «Mold Releasability»

The mold releasability was evaluated by use of the extent of pattern breakage and the extent of line breakage as indices .

Pattern defects, such as pattern breakage and line breakage, during release were at most 1% of the entire pattern: O Pattern defects, such as pattern breakage and line breakage, during release were more than 1% of the entire pattern: ^x

«Resist Pattern Shape and Residual Layer Thickness»

The pattern height and the mold depth were compared with each other, and the difference therebetween was used as the index of the pattern formability.

* Pattern shape

Difference between the protrusion height (recess depth) and the mold was less than ±5%: O

Difference between the protrusion height (recess depth) and the mold was within the range of ±5% to ±10%: Δ

Difference between the protrusion height (recess depth) and the mold was more than ±10%: ^x

• Inkjet arrangement pattern-like defects

The presence or absence of defects and foreign substances, which occurred at a frequency corresponding to the inkjet droplet arrangement pattern at the time of observation of a sample after imprinting with an optical microscope, was evaluated as an index for the inkjet arrangement pattern-like defects.

No defect was found (at most 0.1%) : O

Defects were found: ^x

· Residual layer thickness

With respect to each of the bands (1) to (4), the value of the residual layer thickness was obtained with a cross-sectional SEM image of the shape after imprinting at a center area. Also, the layer thickness with respect to each of four directions of each band was obtained, and a PV value obtained from the data was evaluated with the criterion described below.

Shape accuracy

The PV value was at most 8nm, and the distribution was within the allowable range: O

The PV value was within the range of 8nm to 12nm: Δ

The PV value was at least 12nm, and the distribution was outside the allowable range: ^x

« Deterioration of Characteristics after Repeated Pattern Formation (50 Times) »

Arnold after an imprinting operation hadbeen repeated 50 times under identical conditions was obtained. Thereafter, a 51st sample was prepared by use of the thus obtained mold. At the time of the preparation of the 51st sample, the releasability and the mold staining were evaluated with the indices described below.

■ The releasability was evaluated by use of the extent of pattern breakage and the extent of line breakage as indices.

Pattern defects, such as pattern breakage and line breakage, during release were at most 1% of the entire pattern: O Pattern defects, such as pattern breakage and line breakage, during release were more than 1% of the entire pattern: *

- The mold staining due to accumulation of a material clinging to the mold was evaluated by use of the extent of deterioration of the height of the imprinted pattern due to the staining as an index.

Deterioration of the height of the pattern protrusion due to accumulation of mold staining was less than 5%: O

Deterioration of the height of the pattern protrusion due to accumulation of mold staining was within the range of 5% to 10%: Δ

Deterioration of the height of the pattern protrusion due to accumulation of mold staining was more than 10%: *

«Shape and Quality during Substrate Processing»

• Substrate processability during RIE dry etching

The difference between the protrusion height and a target height was less than ±5%, and the roughness was identical with the roughness of the mold or smaller than the roughness of the mold: O

The difference between the protrusion height and a target height was within the range of ±5% to ±10%, or the roughness was larger than the roughness of the mold and smaller than +lnm: Δ

The difference between the protrusion height and a target height was more than ±10%, or the roughness was larger by at least lnm than the roughness of the mold: ^x « Deterioration of Characteristics after Repeated Pattern Formation (50 Times) »

Arnold after an imprinting operation hadbeen repeated 50 times under identical conditions was obtained. Thereafter, a 51st sample was prepared by use of the thus obtained mold. At the time of the preparation of the 51st sample, the shape of the imprinted sample was evaluated. Also, the shape of the substrate, which had been processed with etching in the same manner by use of the prepared imprinted sample, was evaluated.

- Pattern shape

Difference between the protrusion height (recess depth) and the mold was more than ±10%: *

< Substrate processability during RIE dry etching

The difference between the protrusion height and a target height was more than ±10%, or the roughness was larger by at least lnm than the roughness of the mold: ^x «Liguid Physical Properties»

The viscosity at a temperature of 25°C was measured by use of a viscometer (RotoVisco RVl, manufactured by HAAKE) .

As shown in Table 1, the effects of the embodiment of the pattern forming method in accordance with the present invention were confirmed.

Table 1

Table 1 - continued

Industrial Applicability

The present invention is appropriately applicable to the patterning of the substrates of patterned media and semiconductor devices .

Claims

1. A pattern forming method, comprising the steps of: i) forming a resist layer on a substrate, the resist layer comprising a resist composition, which is arranged as a plurality of discrete droplets, the resist composition containing a polymerizable compound, a polymerization initiator which is activated by light or an electron beam, and a fluorine-containing polymerizable surfactant,

iv) releasing the mold from the resist layer.

2. A pattern forming method as defined in Claim 1 wherein the content of the polymerizable surfactant in the resist composition is at most 5 mass%.

3. Apattern forming method as defined in Claim 1 or 2 wherein a fluorine-containing polymerizable compound is employed as the polymerizable surfactant, the fluorine-containing polymerizable compound having at least one fluorine-containing group, which is selected from the group consisting of a fluoroalkyl group and a fluoroalkylether group, within a monomer of the polymerizable surfactant.

4. A pattern forming method as defined in Claim 3 wherein a fluorine-containing polymerizable compound is employed as the polymerizable surfactant, the fluorine-containing polymerizable compound having a plurality of pieces of at least one kind of a fluorine-containing group, which is selected from the group consisting of a fluoroalkyl group and a fluoroalkylether group, within a monomer of the polymerizable surfactant, at least two pieces of the fluorine-containing group among the plurality of pieces of the fluorine-containing group being spaced apart from each other by a linking group having a carbon number of at least 2.

5. A pattern forming method as defined in Claim 4 wherein each of at least two pieces of the fluorine-containing group is a fluoroalkyl group having a carbon number of at least 2.

6. A pattern forming method as defined in any of Claims 1 to 5 wherein the polymerizable compound contains a monomer having at least one aromatic group.

7. A pattern forming method as defined in any of Claims 1 to 6 wherein a polyfunctional monomer, which crosslinks by polymerization and forms a polymer having a three-dimensional structure, is employed as the polymerizable compound.

8. A pattern forming method as defined in any of Claims 1 to 7 wherein, before the resist layer is arranged on the substrate, a crosslinker for crosslinking and adhering a surface of the substrate, on which surface the resist layer is to be arranged, and the resist layer with each other is applied to the surface of the substrate, on which surface the resist layer is to be arranged.

9. A process for producing a pattern substrate, comprising: using the resist layer, which has been pattern-formed on the substrate by a pattern forming method as defined in any of Claims 1 to 8, as a mask, and