Pattern forming material and method for producing pattern forming material

Abstract

To provide a pattern forming material with which the smooth etching of a semiconductor film can be carried out.SOLUTION: A pattern forming material according to one embodiment of the present invention has: a first structural unit derived from an alkoxysilane compound represented by the specified general formula (1); a second structural unit derived from a polymerizable monomer represented by the specified general formula (2); and a third structural unit derived from a linking compound represented by the specified general formula (3). The content of carbon atoms in the polymerizable monomer is at least 70 mass%.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a material for pattern formation and a method for manufacturing the material for pattern formation.

Background Art

[0002] In the manufacture of semiconductor devices, it is known to etch a semiconductor film to form a desired structure. In recent years, higher integration of semiconductor devices has been desired, and miniaturization of semiconductor films has been required. Therefore, various etching techniques capable of forming a fine structure in a semiconductor film have been studied. As such an etching technique, for example, a multilayer resist method has been proposed (see, for example, Patent Document 1). In the multilayer resist method, first, an organic film (Spin On Carbon, hereinafter referred to as SOC), an antireflection film containing Si (hereinafter referred to as Si-ARC), and a resist film having a pattern shape are sequentially formed on a semiconductor film. Next, after etching the Si-ARC through the resist film, the SOC is etched through the etched Si-ARC, and the semiconductor film is etched through the SOC. However, in the multilayer resist method described in Patent Document 1, it is necessary to sequentially form the SOC and the Si-ARC on the semiconductor film, which is complicated.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] A main object of the present invention is to provide a material for pattern formation capable of smoothly etching a semiconductor film.

Means for Solving the Problems

[0005] [1] The pattern-forming material according to one embodiment of the present invention has a first structural unit derived from an alkoxysilane compound represented by the following general formula (1), a second structural unit derived from a polymerizable monomer represented by the following general formula (2), and a third structural unit derived from a linking compound represented by the following general formula (3). The third structural unit is bonded to the first structural unit and the second structural unit. [Chemical formula] (In general formula (1), R 1 and R 2 each independently represent an alkyl group having 1 to 6 carbon atoms. n represents an integer from 0 to 2.) [Chemical formula] (In general formula (2), R 3 represents a monovalent organic group. X represents a polymerizable functional group.) [Chemical formula] (In general formula (3), R 4 and R 5 each independently represent an alkyl group having 1 to 6 carbon atoms. R 6 represents an alkylene group. Y represents a polymerizable functional group that can polymerize with X in the above general formula (2). m represents an integer from 0 to 2.) The content ratio of carbon atoms in the above polymerizable monomer is 70% by mass or more. [2] In the pattern-forming material described in [1] above, the content ratio of the first structural unit may be 35 mol or more and 85 mol or less with respect to 1 mol of the third structural unit. Also, the content ratio of the second structural unit may be 15 mol or more and 65 mol or less with respect to 1 mol of the third structural unit. [3] In the pattern-forming material described in [1] above, the content ratio of the first structural unit may be 45 mol or more and 75 mol or less with respect to 1 mol of the third structural unit. Also, the content ratio of the second structural unit may be 25 mol or more and 55 mol or less with respect to 1 mol of the third structural unit. [4] In the pattern-forming material according to any one of [1] to [3] above, the alkoxysilane compound may consist only of a tetraalkoxysilane compound in which n is 0 in the general formula (1). [5] In the pattern-forming material according to any one of [1] to [4] above, in the general formula (2), R 3 The organic group represented by may be an aryl group. [6] In the pattern-forming material according to [5] above, in the general formula (2), R 3 The organic group represented by may be a polycyclic aryl group. [7] A method for producing a pattern-forming material according to another aspect of the present invention includes a step of polymerizing an alkoxysilane compound represented by the general formula (1), a polymerizable monomer represented by the general formula (2) and having a carbon atom content of 70% by mass or more, and a linking compound represented by the general formula (3). [Advantages of the Invention]

[0006] According to an embodiment of the present invention, a pattern-forming material capable of smoothly performing etching of a semiconductor film can be realized. [Brief Description of the Drawings]

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments. Also, for the sake of clarity in the description, the drawings may schematically represent the width, thickness, shape, etc. of each part as compared with the embodiments, but this is merely an example and does not limit the interpretation of the present invention.

[0009] A. Outline of the Material for Pattern Formation The material for pattern formation in one embodiment has a first structural unit derived from an alkoxysilane compound represented by the following general formula (1), a second structural unit derived from a polymerizable monomer represented by the following general formula (2), and a third structural unit derived from a linking compound represented by the following general formula (3). The material for pattern formation is typically a terpolymer of an alkoxysilane compound represented by the following general formula (1), a polymerizable monomer represented by the following general formula (2), and a linking compound represented by the following general formula (3).

CHEM.

CHEM.

CHEM.

[0010] The content ratio of carbon atoms in the polymerizable monomer is preferably 80% by mass or more, more preferably 85% by mass or more. On the other hand, the content ratio of carbon atoms in the polymerizable monomer is, for example, 98% by mass or less, and for example, 95% by mass or less. When the content ratio of carbon atoms in the polymerizable monomer is within such a range, the above-described gradient functional material layer can be stably formed using the material for pattern formation.

[0011] The content ratio of the first structural unit is, for example, 5 mol or more, preferably 35 mol or more, more preferably 45 mol or more, still more preferably 50 mol or more, and particularly preferably 55 mol or more with respect to 1 mol of the third structural unit. On the other hand, the content ratio of the first structural unit is, for example, 95 mol or less, preferably 85 mol or less, more preferably 75 mol or less, still more preferably 70 mol or less, and particularly preferably 65 mol or less with respect to 1 mol of the third structural unit. The content ratio of the second structural unit is, for example, 5 mol or more, preferably 15 mol or more, more preferably 25 mol or more, more preferably 30 mol or more, and still more preferably 35 mol or more with respect to 1 mol of the third structural unit. On the other hand, the content ratio of the second structural unit is, for example, 95 mol or less, preferably 65 mol or less, more preferably 55 mol or less, still more preferably 50 mol or less, and particularly preferably 45 mol or less with respect to 1 mol of the third structural unit. The content ratio of the second structural unit is, for example, 0.5 mol to 8.0 mol, preferably 0.6 mol to 5.0 mol, and more preferably 1.0 mol to 2.5 mol with respect to 1 mol of the first structural unit. When using a material for pattern formation in which the content ratio of the first structural unit and / or the content ratio of the second structural unit is within such a range, the semiconductor film can be etched more precisely.

[0012] Hereinafter, the details of each constituent unit of the material for pattern formation will be described.

[0013] B. The first structural unit derived from an alkoxysilane compound The alkoxysilane compound is represented by the above general formula (1). In the general formula (1), R 1 As the alkyl group represented by, preferably a linear alkyl group having 1 to 6 carbon atoms is mentioned, more preferably a linear alkyl group having 1 to 3 carbon atoms is mentioned, and particularly preferably a methyl group is mentioned. In the general formula (1), R 2 As the alkyl group represented by, for example, the same alkyl group as the above-mentioned R 1 is mentioned, and preferably an ethyl group is mentioned. In the general formula (1), R 1 and R 2 may be the same as each other or different from each other.

[0014] In the general formula (1), n preferably represents 0 or 1, and more preferably 0. When n is 0 in the general formula (1), the alkoxysilane compound is a tetraalkoxysilane compound. When n is 1 or more in the general formula (1), the alkoxysilane compound is an alkylalkoxysilane compound.

[0015] Specific examples of the alkoxysilane compound include tetraalkoxysilanes such as tetramethoxysilane and tetraethoxysilane (TEOS); alkyltrialkoxysilanes such as methyltrimethoxysilane and methyltriethoxysilane; dialkyldialkoxysilanes such as dimethyldimethoxysilane and dimethyldiethoxysilane. The alkoxysilane compound can be used alone or in combination.

[0016] In one embodiment, the alkoxysilane compound consists only of a tetraalkoxysilane compound in which n is 0 in the general formula (1). That is, the alkoxysilane compound contains a tetraalkoxysilane compound and substantially does not contain an alkylalkoxysilane compound. When the alkoxysilane compound consists only of a tetraalkoxysilane compound, the pattern-forming material contains, as the first structural unit, only the structural unit derived from the tetraalkoxysilane compound. When such a pattern-forming material is used, the semiconductor film can be etched more precisely.

[0017] The molecular weight of the alkoxysilane compound is, for example, 200 g / mol to 300 g / mol, and also, for example, 150 g / mol to 250 g / mol.

[0018] C. Second structural unit derived from the polymerizable monomer The polymerizable monomer is represented by the above general formula (2). The polymerizable functional group represented by X in the general formula (2) typically contains an ethylenically unsaturated bond. Examples of the polymerizable functional group represented by X in the general formula (2) include a vinyl group and a (meth)acryloyl group. In this specification, the “(meth)acryloyl group” includes an acryloyl group and a methacryloyl group.

[0019] Among these polymerizable functional groups, a vinyl group is preferably mentioned. In one embodiment, the polymerizable monomer is a vinyl group-containing monomer represented by the following general formula (2-1).

Chemical formula

[0020] In each of the general formulas (2) and (2-1), the number of carbon atoms of the monovalent organic group represented by R 3 is, for example, 4 or more, preferably 6 or more, more preferably 8 or more, and still more preferably 10 or more. Examples of such organic groups include an alkyl group, an aryl group, and an aralkyl group, and preferably an aryl group.

[0021] Specific examples of the aryl group include monocyclic aryl groups such as a phenyl group and a tolyl group; polycyclic aryl groups such as a naphthyl group, a pyrenyl group, an anthracenyl group, and a carbazolyl group. Among these aryl groups, preferably a polycyclic aryl group is mentioned. When the organic group is an aryl group, the content ratio of carbon atoms in the polymerizable monomer can be stably adjusted within the above-mentioned range. Further, when the organic group is a polycyclic aryl group, excellent heat resistance can be imparted to the above-mentioned inclined functional material layer.

[0022] Specific examples of such polymerizable monomers include monocyclic aromatic ring-containing polymerizable monomers such as styrene; polycyclic aromatic ring-containing polymerizable monomers such as vinyl naphthalene, vinyl anthracene, vinyl pyrene, and vinyl carbazole; and mixtures thereof. Among these polymerizable monomers, preferably styrene, vinyl naphthalene, vinyl anthracene, vinyl pyrene, and vinyl carbazole are mentioned, and more preferably vinyl naphthalene, vinyl anthracene, vinyl pyrene, and vinyl carbazole are mentioned.

[0023] The molecular weight of the polymerizable monomer is, for example, 80 g / mol to 400 g / mol, preferably 100 g / mol to 250 g / mol, and more preferably 140 g / mol to 240 g / mol.

[0024] D. The third structural unit derived from the linking compound The linking compound is represented by the above general formula (3). The linking compound includes an alkoxysilyl group capable of reacting with the above-mentioned alkoxysilane compound, a polymerizable functional group capable of reacting with the above-mentioned polymerizable monomer, and an alkylene group linking them.

[0025] In the general formula (3), the polymerizable functional group represented by Y typically contains an ethylenically unsaturated bond. Examples of the polymerizable functional group represented by Y in the general formula (3) include a vinyl group, a (meth)acryloyl group, and a (meth)acryloyloxy group.

[0026] Among these polymerizable functional groups, a (meth)acryloyloxy group is preferably mentioned. In one embodiment, the linking compound is a (meth)acryloyloxy group-containing alkoxysilane represented by the following general formula (3-1).

Chemical formula

[0027] In each of the general formulas (3) and (3-1), examples of the alkyl group represented by R 4 include the same alkyl groups as those of R 1 in the general formula (1) described above. In each of the general formulas (3) and (3-1), examples of the alkyl group represented by R 5 include the same alkyl groups as those of R 1 in the general formula (1) described above. In each of the general formulas (3) and (3-1), R 4 and R 5 may be the same as each other or different from each other.

[0028] In each of the general formulas (3) and (3-1), examples of the alkylene group represented by R 6 include an alkylene group having 1 to 10 carbon atoms, preferably an alkylene group having 1 to 6 carbon atoms, more preferably an alkylene group having 1 to 3 carbon atoms, and particularly preferably a propylene group.

[0029] In each of general formulas (3) and (3-1), R 7 preferably represents a methyl group.

[0030] In each of general formulas (3) and (3-1), m preferably represents 0 or 1, and more preferably 0.

[0031] Specific examples of such a linking compound include 3-methacryloxypropyltrimethoxysilane (MP silane) and 3-methacryloxypropyltriethoxysilane. The linking compound can be used alone or in combination.

[0032] E. Method for Producing Material for Pattern Formation Next, a method for producing a material for pattern formation according to one embodiment of the present invention will be described. The method for producing the material for pattern formation described above typically includes a step of polymerizing the above-described alkoxysilane compound, the above-described linking compound, and the above-described polymerizable monomer. In the method for producing the material for pattern formation, the order of polymerization of the alkoxysilane compound, the linking compound, and the polymerizable monomer is not particularly limited.

[0033] In one embodiment, the method for producing the material for pattern formation includes a step of polycondensing the above-described alkoxysilane compound to prepare a siloxane oligomer, a step of polymerizing the above-described linking compound and the above-described polymerizable monomer to prepare a copolymer, and a step of reacting the siloxane oligomer and the copolymer to obtain the material for pattern formation.

[0034] E-1. Step of Preparing Siloxane Oligomer In the step of preparing the siloxane oligomer, typically, first, the above-described alkoxysilane compound and a polar solvent are mixed to prepare an alkoxysilane solution. Examples of the polar solvent include alcohols, ketones, and ethers, and alcohols are preferably used. The polar solvent can be used alone or in combination.

[0035] Next, an acidic solution is added to the alkoxysilane solution to prepare a first mixed solution. The acidic solution contains an acid component and water. The acidic solution may further contain the above-mentioned polar solvent. Examples of the acid component include hydrochloric acid, sulfuric acid, and nitric acid, and hydrochloric acid is preferably used. The concentration of the acid component in the acidic solution is, for example, 0.5% by mass to 2.0% by mass.

[0036] Thereafter, the first mixed solution is stirred. The stirring time is, for example, 1 hour to 10 hours, preferably 4 hours to 8 hours. The temperature of the first mixed solution during stirring is, for example, 0°C to 100°C, preferably 20°C to 60°C.

[0037] As a result, the alkoxysilyl group of the alkoxysilane compound is hydrolyzed to form a silanol group, and the silanol groups and / or the silanol group and the ethoxysilyl group undergo a polycondensation reaction. As a result, a siloxane oligomer having a first structural unit derived from the alkoxysilane compound and having a silanol group remaining at the molecular end is formed.

[0038] In one embodiment, a first raw material solution containing a siloxane oligomer is obtained. Thereafter, if necessary, the acid component and water may be removed from the first raw material solution by known means.

[0039] E-2. Step of preparing a copolymer In the step of preparing a copolymer, typically, first, the above-mentioned linking compound and the above-mentioned polymerizable monomer are mixed so that the second structural unit and the third structural unit have the above-mentioned molar ratio to prepare a second mixed solution. Thereafter, a polymerization initiator is added to the second mixed solution and stirred. The polymerization initiator can be optionally and appropriately selected according to the polymerizable functional groups of the linking compound and the polymerizable monomer. Typically, radical polymerization initiators are mentioned as the polymerization initiator. Examples of radical polymerization initiators include azo compounds such as 2,2′-azobisisobutyronitrile (AIBN); peroxides such as benzoyl peroxide (BPO). The radical polymerization initiator can be used alone or in combination. Among radical polymerization initiators, preferably azo compounds are mentioned, and more preferably AIBN is mentioned.

[0040] Next, the second mixed solution added with the polymerization initiator is stirred. The stirring time is, for example, 5 hours to 15 hours, preferably 7 hours to 10 hours. The temperature of the second mixed solution during stirring is, for example, 50°C to 120°C, preferably 70°C to 100°C.

[0041] Thereby, the polymerizable functional groups (X) of the polymerizable monomer polymerize with each other, and the polymerizable functional group (X) of the polymerizable monomer and the polymerizable functional group (Y) of the linking compound polymerize. As a result, a copolymer having a second structural unit derived from the polymerizable monomer and a third structural unit derived from the linking compound is produced.

[0042] In one embodiment, the copolymer is dissolved in the above-mentioned polar solvent to prepare a second raw material solution. Preferred examples of the polar solvent include ketones, and more preferably methyl ethyl ketone (MEK).

[0043] E-3. Reaction step of siloxane oligomer and copolymer In the reaction step of the siloxane oligomer and the copolymer, typically, the siloxane oligomer and the copolymer are subjected to a sol-gel reaction. In one embodiment, a first raw material solution containing a siloxane oligomer and a second raw material solution containing a copolymer are mixed so that the first to third structural units have the above-mentioned molar ratio to prepare a third mixed solution in a sol state. Then, the silanol residue of the siloxane oligomer and the alkoxysilyl group of the copolymer react over time to prepare a gel-state pattern-forming material.

[0044] E-4. Modification of the method for producing the pattern-forming material The method for producing the pattern-forming material is not limited to the above-described embodiment. In another embodiment, the method for producing the pattern-forming material includes a step of polycondensing the above-described alkoxysilane compound and the above-described linking compound to prepare a copolymer, a step of polymerizing the above-described polymerizable monomer to adjust an oligomer, and a step of reacting the copolymer and the oligomer to obtain a pattern-forming material. Also by this, the pattern-forming material can be produced.

[0045] F. Method for using the pattern-forming material The pattern-forming material is typically used by being dissolved in an organic solvent. That is, it can be used in a state of a solution in which the pattern-forming material is dissolved in an organic solvent (hereinafter referred to as a pattern-forming material solution). The pattern-forming material solution contains the above-described pattern-forming material and an organic solvent. The pattern-forming material solution is typically an organic solvent solution of the pattern-forming material. The organic solvent can dissolve the pattern-forming material. Examples of the organic solvent include polypropylene glycol monoethyl ether acetate, polypropylene glycol monoethyl ether, methyl amyl ketone, ethyl lactate, ethoxyethyl propionate, and methoxymethyl propionate. Preferably, polypropylene glycol monoethyl ether acetate, methyl amyl ketone, and ethyl lactate are mentioned.

[0046] The pattern-forming material solution may further contain any suitable additive. Examples of the additive include a surfactant and an adhesion enhancer. The additives can be used alone or in combination.

[0047] G. Method for etching a semiconductor film (method for manufacturing a semiconductor film having an etching portion) Next, with reference to FIGS. 1 to 5, a method for etching a semiconductor film using the above-described pattern-forming material solution will be described.

[0048] As shown in FIG. 1, first, a semiconductor film 2 is prepared. In one embodiment, the semiconductor film 2 is provided on a semiconductor substrate 4. The semiconductor substrate 4 is typically a silicon substrate. The semiconductor film 2 is composed of any suitable semiconductor material. Representative semiconductor films 2 are silicon oxide, silicon nitride, and polysilicon. The thickness of the semiconductor film 2 is, for example, 0.2 μm to 2.0 μm, and also, for example, 0.5 μm to 1.5 μm.

[0049] Next, a pattern-forming material solution is applied onto the semiconductor film 2 to form a coating film 1a. At this time, the second structural unit derived from the polymerizable monomer represented by the general formula (2) moves to the semiconductor film 2 side, and the first structural unit derived from the alkoxysilane compound represented by the general formula (1) moves to the side opposite to the semiconductor film 2 (i.e., the surface side).

[0050] Next, the coating film 1a is dried under any suitable conditions to form an inclined functional material layer 1. In the inclined functional material layer 1, the content ratio of silicon (Si) continuously increases from the semiconductor film 2 side toward the surface side, and the content ratio of carbon (C) continuously increases from the surface side toward the semiconductor film 2 side. The inclined functional material layer 1 integrally has a carbon-rich portion located on the semiconductor film 2 side and a silicon-rich portion located on the side opposite to the semiconductor film 2 with respect to the carbon-rich portion.

[0051] The carbon-rich portion of the inclined functional material layer 1 typically contacts the semiconductor film 2. The content ratio of carbon atoms in the carbon-rich portion is, for example, 80 mass% or more, preferably 90 mass% or more, more preferably 95 mass% or more. The upper limit of the content ratio of carbon atoms in the carbon-rich portion is typically 100 mass%. The content ratio of silicon atoms in the carbon-rich portion is, for example, less than 20% by mass, preferably less than 5% by mass, and more preferably less than 1% by mass.

[0052] The silicon-rich portion of the gradient functional material layer 1 is typically continuous with the carbon-rich portion. The content ratio of silicon atoms in the silicon-rich portion is, for example, 25% by mass or more, preferably 30% by mass or more, and more preferably 40% by mass or more. The upper limit of the content ratio of silicon atoms in the silicon-rich portion is typically 50% by mass. The content ratio of carbon atoms in the silicon-rich portion is, for example, less than 75% by mass, preferably less than 70% by mass, and more preferably less than 60% by mass.

[0053] Next, as shown in FIG. 2, a resist film 3 having a predetermined pattern shape is formed on the gradient functional material layer 1. As a method for forming the resist film, any appropriate method is adopted. Typically, photolithography is mentioned as a method for forming the resist film. The resist film 3 partially exposes the surface of the gradient functional material layer 1. The surface portion of the gradient functional material layer 1 exposed from the resist film 3 corresponds to the portion to be etched of the semiconductor film 2.

[0054] Next, as shown in FIG. 3, the gradient functional material layer 1 is primarily etched through the resist film 3. Typically, reactive ion etching using a halogen gas is mentioned as a primary etching method. At this time, in the gradient functional material layer 1 exposed from the resist film 3, the silicon-rich portion is removed while the carbon-rich portion is not removed. That is, in the primary etching, only the silicon-rich portion of the gradient functional material layer 1 is etched. As a result, a recess 11 is formed in the gradient functional material layer 1. The bottom surface of the recess 11 is composed of the carbon-rich portion of the gradient functional material layer 1.

[0055] Next, as shown in FIG. 4, the resist film 3 and the carbon-rich portion of the inclined functional material layer 1 are secondarily etched. As a typical secondary etching method, reactive ion etching using oxygen gas can be mentioned. At this time, the resist film is removed and the carbon-rich portion exposed from the recess is removed. As a result, an opening 12 is formed in the inclined functional material layer 1. The opening 12 exposes the portion to be etched in the semiconductor film 2.

[0056] Next, as shown in FIG. 5, the portion of the semiconductor film 2 exposed from the opening 12 of the inclined functional material layer 1 is tertially etched. As a typical tertiary etching method, reactive ion etching using a halogen gas can be mentioned. At this time, the silicon-rich portion of the inclined functional material layer 1 and a part of the semiconductor film 2 exposed from the opening 12 are removed. As a result, an etching portion 21 is formed at a desired position in the semiconductor film 2.

[0057] The etching portion 21 is typically a recess. The depth of the etching portion 21 (dimension in the thickness direction of the semiconductor film 2) is arbitrarily and appropriately adjusted according to the use of the semiconductor film 2. The depth of the etching portion 21 is, for example, 0.10 μm or more, preferably 0.20 μm or more, more preferably 0.40 μm or more, and even more preferably 0.55 μm or more.

[0058] Thereafter, if necessary, the remaining carbon-rich portion on the semiconductor film 2 is removed. The method for removing the carbon-rich portion is not particularly limited. As a method for removing the carbon-rich portion, for example, reactive ion etching using oxygen gas can be mentioned. Through the above, the semiconductor film 2 having the etching portion 21 is manufactured.

Example

[0059] Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited by these examples.

[0060] <Examples 1 to 9> Tetraethoxysilane (TEOS, an alkoxysilane compound) and ethanol (a polar solvent) were mixed to prepare an alkoxysilane solution. While stirring the alkoxysilane solution at room temperature (25 °C), an acidic solution was dropped into the alkoxysilane solution. The acidic solution contained concentrated hydrochloric acid (acid component), ethanol, and pure water. The hydrochloric acid concentration in the acidic solution was 1.2 mass%. Thereafter, the first mixture of the alkoxysilane solution and the acidic solution was stirred for 5 hours. At this time, the ethoxysilyl groups of TEOS were hydrolyzed to form silanol groups, and the silanol groups and / or the silanol groups and ethoxysilyl groups underwent a polycondensation reaction. As a result, a siloxane oligomer having a first structural unit derived from TEOS was formed. The siloxane oligomer had silanol residues. Thereby, a first raw material solution containing the siloxane oligomer was obtained. Thereafter, hydrochloric acid, ethanol, and water were removed from the first raw material solution by known means.

[0061] Also, 3-methacryloxypropyltrimethoxysilane (MP silane, a linking compound) and styrene (a polymerizable monomer) were mixed at the molar ratios shown in Table 1 to prepare a second mixture. The content ratio of carbon atoms in the polymerizable monomer (= total atomic weight C of carbon atoms contained in the polymerizable monomer / molecular weight Mw of the polymerizable monomer × 100) is shown in Table 1. Next, 2,2′-azobisisobutyronitrile (AIBN, a radical polymerization initiator) was added to the second mixture, and then the mixture was stirred at 75 °C for 3 hours. Thereby, the oxymethacryloyl group of MP silane (linking compound) and the vinyl group of styrene underwent radical polymerization to prepare a copolymer. The copolymer contained a second structural unit derived from styrene and a third structural unit derived from MP silane. Next, the obtained copolymer was dissolved in methyl ethyl ketone (MEK) to prepare a second raw material solution.

[0062] Next, the first raw material liquid and the second raw material liquid were mixed so that the molar ratio of TEOS, MP silane, and styrene became the values in Table 1, and a third mixed liquid in a sol state was prepared. Then, the silanol residues of the siloxane oligomer and the ethoxysilyl groups of the copolymer underwent a polycondensation reaction over time, and a pattern-forming material in a gel state was prepared. The pattern-forming material contained a first structural unit derived from TEOS, a second structural unit derived from styrene, and a third structural unit derived from MP silane.

[0063] <Comparative Example 1> After preparing a first raw material liquid containing a siloxane oligomer in the same manner as in Example 1, 3-methacryloxypropyltrimethoxysilane (MP silane, a linking compound) was added to the first raw material liquid so that the molar ratio of TEOS and MP silane became the values in Table 1, and they were reacted to obtain a pattern-forming material in a gel state.

[0064] <Comparative Example 2> A copolymer was prepared in the same manner as in Example 1 except that the molar ratio of MP silane (linking compound) and styrene (polymerizable monomer) was changed to the values shown in Table 1, and the copolymer was used as the pattern-forming material.

[0065] <Examples 10 to 13 and Comparative Example 3> A pattern-forming material was prepared in the same manner as in Example 4 except that styrene was changed to the polymerizable monomers shown in Table 2.

[0066] <Example 14> A pattern-forming material was prepared in the same manner as in Example 10 except that TEOS and methyltrimethoxysilane were used in combination as the alkoxysilane compound.

[0067] <Evaluation of Etching Depth> Using the pattern-forming materials obtained in the examples and comparative examples, etching of the semiconductor film was carried out. Specifically, the pattern-forming materials obtained in the examples and comparative examples were dissolved in propylene glycol monoethyl acetate (organic solvent) to prepare a pattern-forming material solution. Also, a silicon substrate having an oxide film with a thickness of 1.0 μm as a semiconductor film was prepared. Next, a material solution for patterning was applied onto the thermal oxide film, and the coating film was heated and dried. As a result, a gradient functional material layer was formed on the oxide film. The gradient functional material layer integrally had a carbon-rich portion located on the semiconductor film side and a silicon-rich portion located on the surface side.

[0068] Next, a resist film having an arbitrary appropriate pattern shape was formed on the gradient functional material layer. The resist film having the pattern shape partially exposed the gradient functional material layer.

[0069] Next, the gradient functional material layer was primarily etched through the resist film by reactive ion etching using a halogen gas. As a result, only the silicon-rich portion exposed from the resist film was etched, and a recess was formed in the gradient functional material layer (see FIG. 3). Note that the recess exposed the carbon-rich portion.

[0070] Thereafter, the resist film and the carbon-rich portion of the gradient functional material layer were secondarily etched by reactive ion etching using oxygen gas. As a result, the resist film was removed, and the carbon-rich portion exposed from the recess was removed. Consequently, an opening for partially exposing the semiconductor film was formed in the gradient functional material layer (see FIG. 4).

[0071] Next, a part of the semiconductor film exposed from the opening of the gradient functional material layer was tertially etched by reactive ion etching using a halogen gas. As a result, the silicon-rich portion of the gradient functional material layer and the semiconductor film (oxide film) exposed from the opening were removed, and an etched portion was formed in the semiconductor film (oxide film) (see FIG. 5). Thereafter, the carbon-rich portion remaining on the semiconductor film was removed by reactive ion etching using oxygen gas.

[0072] As described above, the etching of the semiconductor film was completed. The depth of the etched portion (etching depth) formed in the oxide film of the semiconductor film was measured and evaluated according to the following criteria. The results are shown in Tables 1 and 2. ◎: The etching depth is 0.55 μm or more, 〇: The etching depth is 0.40 μm or more and less than 0.55 μm, △: The etching depth is 0.10 μm or more and less than 0.40 μm, ×: The etching depth is less than 0.10 μm.

[0073]

Table 1

[0074]

Table 2

[0075] <Evaluation> As is clear from Tables 1 and 2, when the carbon atom content ratio in the polymerizable monomer is 70% by mass or more, by applying the pattern forming material solution containing the pattern forming material on the semiconductor film, it can be seen that the inclined functional material layer can be smoothly formed on the semiconductor film. Therefore, compared with the multilayer resist method, the etching of the semiconductor film can be carried out smoothly.

Industrial Applicability

[0076] The pattern forming material according to the embodiment of the present invention can be used in the manufacture of various industrial products, and can be particularly suitably used for the etching of semiconductor films.

Explanation of Signs

[0077] 1 Inclined functional material layer 2 Semiconductor film 3 Resist film 4 Semiconductor substrate

Claims

1. a first structural unit derived from an alkoxysilane compound represented by the following general formula (1); a second structural unit derived from a polymerizable monomer represented by the following general formula (2); a third structural unit derived from a linking compound represented by the following general formula (3), the third structural unit being bonded to the first structural unit and the second structural unit; and having, a pattern forming material, wherein the content ratio of carbon atoms in the polymerizable monomer is 70% by mass or more: 【Chemical 1】 (In general formula (1), R １ and R ２ each independently represents an alkyl group having 1 to 6 carbon atoms; n represents an integer from 0 to 2;) 【Chemical Formula 2】 (In general formula (2), R ３ represents a monovalent organic group; X represents a polymerizable functional group;) 【Chemical Formula 3】 (In general formula (3), R ４ and R ５ each independently represents an alkyl group having 1 to 6 carbon atoms; R ６ represents an alkylene group; Y represents a polymerizable functional group polymerizable with X in the general formula (2); m represents an integer from 0 to 2.)

2. The content ratio of the first structural unit is 35 mol or more and 85 mol or less with respect to 1 mol of the third structural unit, The content ratio of the second structural unit is 15 mol or more and 65 mol or less with respect to 1 mol of the third structural unit. The pattern forming material according to claim 1.

3. The content ratio of the first structural unit is 45 mol or more and 75 mol or less with respect to 1 mol of the third structural unit, The content ratio of the second structural unit is 25 mol or more and 55 mol or less with respect to 1 mol of the third structural unit. The pattern forming material according to claim 1.

4. The alkoxysilane compound consists only of a tetraalkoxysilane compound in which n is 0 in the general formula (1). The pattern forming material according to any one of claims 1 to 3.

5. In the above general formula (2), R ３ The pattern-forming material according to any one of claims 1 to 3, wherein the organic group represented by is an aryl group.

6. In the above general formula (2), R ３ The pattern-forming material according to claim 5, wherein the organic group represented by is a polycyclic aryl group.

7. A method for producing a pattern forming material, comprising a step of polymerizing an alkoxysilane compound represented by the following general formula (1), a polymerizable monomer represented by the following general formula (2) and having a carbon atom content ratio of 70% by mass or more, and a linking compound represented by the following general formula (3): 【Chemical 1】 (In general formula (1), R １ and R ２ each independently represent an alkyl group having 1 to 6 carbon atoms; n represents an integer from 0 to 2;) 【Chemical 2】 (In general formula (2), R ３ represents a monovalent organic group; X represents a polymerizable functional group;) 【Chemical Formula 3】 (In general formula (3), R ４ and R ５ each independently represents an alkyl group having 1 to 6 carbon atoms; R ６ represents an alkylene group; Y represents a polymerizable functional group polymerizable with X in the general formula (2); m represents an integer from 0 to 2.)

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