Pattern forming material and method for producing pattern forming material

Abstract

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

Description

Pattern forming material and method for producing pattern forming material

[0001] The present invention relates to a pattern-forming material and a method for producing the pattern-forming material.

[0002] In the manufacture of semiconductor devices, it is known to form desired structures by etching semiconductor films. In recent years, there has been a demand for higher integration of semiconductor devices, resulting in a demand for finer structures in semiconductor films. Accordingly, various etching techniques capable of forming finer structures in semiconductor films have been investigated. For example, a multilayer resist method has been proposed as one such etching technique (see, for example, Patent Document 1). In the multilayer resist method, an organic film (spin-on-carbon, hereinafter referred to as SOC), a Si-containing anti-reflective film (hereinafter referred to as Si-ARC), and a patterned resist film are first formed, in that order, on a semiconductor film. Next, the Si-ARC is etched through the resist film, and then the SOC is etched through the etched Si-ARC, and the semiconductor film is etched through the SOC. However, the multilayer resist method described in Patent Document 1 is complicated because it requires the sequential formation of the SOC and Si-ARC on the semiconductor film.

[0003] Japanese Patent Application Laid-Open No. 2018-173521

[0004] A primary object of the present invention is to provide a pattern forming material that allows smooth etching of a semiconductor film.

[0005] [1] A pattern formation 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), wherein the third structural unit bonds to the first structural unit and the second structural unit. (In general formula (1), R １ and R ２ each independently represents an alkyl group having 1 to 6 carbon atoms, and n represents an integer of 0 to 2. (In general formula (2), R ３represents a monovalent organic group; and X represents a polymerizable functional group. (In general formula (3), R ４ and R ５ R each independently represents an alkyl group having 1 to 6 carbon atoms. ６ represents an alkylene group. Y represents a polymerizable functional group polymerizable with X in general formula (2). m represents an integer of 0 to 2.) The carbon atom content in the polymerizable monomer is 70 mass% or more. [2] In the pattern-forming material described in [1] above, the content of the first structural unit may be 35 mol or more and 85 mol or less per mole of the third structural unit. The content of the second structural unit may be 15 mol or more and 65 mol or less per mole of the third structural unit. [3] In the pattern-forming material described in [1] above, the content of the first structural unit may be 45 mol or more and 75 mol or less per mole of the third structural unit. The content of the second structural unit may be 25 mol or more and 55 mol or less per mole 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 solely of a tetraalkoxysilane compound in which n in the general formula (1) is 0. [5] In the pattern-forming material according to any one of [1] to [4] above, in the general formula (2), R ３ [6] In the pattern formation material according to the above item [5], the organic group represented by R ３ [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) above, a polymerizable monomer represented by the general formula (2) above, the polymerizable monomer having a carbon atom content of 70 mass % or more, and a linking compound represented by the general formula (3) above.

[0006] According to an embodiment of the present invention, a pattern forming material that allows smooth etching of a semiconductor film can be realized.

[0007] Fig. 1 is a schematic cross-sectional view illustrating a process of forming a functionally gradient material layer by applying a pattern formation material solution containing a pattern formation material according to one embodiment of the present invention onto a semiconductor film. Fig. 2 is a schematic cross-sectional view illustrating a process of forming a resist film having a pattern shape on the functionally gradient material layer of Fig. 1. Fig. 3 is a schematic cross-sectional view illustrating a process of primarily etching the functionally gradient material layer of Fig. 2. Fig. 4 is a schematic cross-sectional view illustrating a process of secondarily etching the functionally gradient material layer of Fig. 3. Fig. 5 is a schematic cross-sectional view illustrating a process of etching a semiconductor film through the functionally gradient material layer of Fig. 4.

[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. In addition, in order to clarify the description, the drawings may show the width, thickness, shape, etc. of each part more schematically than in the embodiment, but these are merely examples and do not limit the interpretation of the present invention.

[0009] A. Overview of Pattern Formation Material The pattern formation material 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 pattern formation material 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). (In general formula (1), R １ and R ２ each independently represents an alkyl group having 1 to 6 carbon atoms, and n represents an integer of 0 to 2. (In general formula (2), R ３ represents a monovalent organic group; and X represents a polymerizable functional group. (In general formula (3), R ４ and R ５ R each independently represents an alkyl group having 1 to 6 carbon atoms. ６represents an alkylene group. Y represents a polymerizable functional group polymerizable with X in the general formula (2). m represents an integer of 0 to 2.) The carbon atom content in the polymerizable monomer is 70% by mass or more. According to this configuration, the pattern-forming material has a first structural unit derived from an alkoxysilane compound represented by the general formula (1), a second structural unit derived from a polymerizable monomer represented by the general formula (2), and a third structural unit derived from a linking compound represented by the general formula (3), and the carbon atom content in the polymerizable monomer is 70% by mass or more. Therefore, the pattern-forming material can be suitably used for etching semiconductor films. In etching semiconductor films, a pattern-forming material solution containing the pattern-forming material is typically applied to a semiconductor film to form a functionally gradient material layer on the semiconductor film (see FIG. 1). When a pattern formation material solution is applied to a semiconductor film, the second structural unit derived from the polymerizable monomer represented by the general formula (2) migrates toward the semiconductor film, and the first structural unit derived from the alkoxysilane compound represented by the general formula (1) migrates toward the opposite side of the semiconductor film (i.e., the surface side). As a result, in the functionally gradient material layer, the carbon (C) content can continuously increase from the surface side toward the semiconductor film side, and the silicon (Si) content can continuously increase from the semiconductor film side toward the surface side. Therefore, the functionally gradient material layer can integrally have a carbon-rich portion located on the semiconductor film side and a silicon-rich portion located on the surface side. The carbon-rich portion of the functionally gradient material layer can function similarly to an SOC in a multilayer resist method. Furthermore, the silicon-rich portion of the functionally gradient material layer can function similarly to an Si-ARC in a multilayer resist method. In other words, by applying a pattern formation material solution to a semiconductor film, a carbon-rich portion that functions similarly to an SOC and a silicon-rich portion that functions similarly to an Si-ARC can be simultaneously formed. As a result, the semiconductor film can be etched more smoothly than with the multilayer resist method (see FIGS. 2 to 5). Furthermore, by appropriately changing the composition of the pattern-forming material, the thickness of each of the carbon-rich portion and the silicon-rich portion can be appropriately adjusted. As a result, the etching depth in the semiconductor film can be adjusted with precision.

[0010] The carbon atom content in the polymerizable monomer is preferably 80% by mass or more, more preferably 85% by mass or more. On the other hand, the carbon atom content in the polymerizable monomer is, for example, 98% by mass or less, or, for example, 95% by mass or less. When the carbon atom content in the polymerizable monomer is in this range, the above-mentioned functionally gradient material layer can be stably formed using the pattern-forming material.

[0011] The content ratio of the first structural unit is, for example, 5 moles or more, preferably 35 moles or more, more preferably 45 moles or more, even more preferably 50 moles or more, particularly preferably 55 moles or more, relative to 1 mole of the third structural unit.On the other hand, the content ratio of the first structural unit is, for example, 95 moles or less, preferably 85 moles or less, more preferably 75 moles or less, even more preferably 70 moles or less, particularly preferably 65 moles or less, relative to 1 mole of the third structural unit.The content ratio of the second structural unit is, for example, 5 moles or more, preferably 15 moles or more, more preferably 25 moles or more, more preferably 30 moles or more, even more preferably 35 moles or more, relative to 1 mole of the third structural unit.On the other hand, the content ratio of the second structural unit is, for example, 95 moles or less, preferably 65 moles or less, more preferably 55 moles or less, even more preferably 50 moles or less, particularly preferably 45 moles or less, relative to 1 mole of the third structural unit. The content 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, relative to 1 mol of the first structural unit. By using a pattern-forming material in which the content of the first structural unit and / or the content of the second structural unit falls within such ranges, the semiconductor film can be etched more precisely.

[0012] Each structural unit of the pattern forming material will be described in detail below.

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

[0014] In general formula (1), n ​​preferably represents 0 or 1, and more preferably 0. When n is 0 in general formula (1), the alkoxysilane compound is a tetraalkoxysilane compound. When n is 1 or more in 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, and dialkyldialkoxysilanes such as dimethyldimethoxysilane and dimethyldiethoxysilane. The alkoxysilane compounds may be used alone or in combination.

[0016] In one embodiment, the alkoxysilane compound consists solely of a tetraalkoxysilane compound in which n is 0 in 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 solely of a tetraalkoxysilane compound, the pattern-forming material contains only structural units derived from the tetraalkoxysilane compound as the first structural unit. Use of such a pattern-forming material enables more precise etching of semiconductor films.

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

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

[0019] Among these polymerizable functional groups, a vinyl group is preferable. In one embodiment, the polymerizable monomer is a vinyl group-containing monomer represented by the following general formula (2-1): (In general formula (2-1), R ３ represents a monovalent organic group.)

[0020] In each of the general formulas (2) and (2-1), R ３ The number of carbon atoms in the monovalent organic group represented by the formula (I) is, for example, 4 or more, preferably 6 or more, more preferably 8 or more, and even more preferably 10 or more. Examples of such an organic group 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 phenyl and tolyl groups; and polycyclic aryl groups such as naphthyl, pyrenyl, anthracenyl, and carbazolyl groups. Among these aryl groups, polycyclic aryl groups are preferred. When the organic group is an aryl group, the carbon atom content in the polymerizable monomer can be stably adjusted within the above-mentioned range. Furthermore, when the organic group is a polycyclic aryl group, excellent heat resistance can be imparted to the functionally gradient 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 vinylnaphthalene, vinylanthracene, vinylpyrene, and vinylcarbazole; and mixtures thereof. Among these polymerizable monomers, preferred are styrene, vinylnaphthalene, vinylanthracene, vinylpyrene, and vinylcarbazole, and more preferred are vinylnaphthalene, vinylanthracene, vinylpyrene, and vinylcarbazole.

[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. Third structural unit derived from 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 alkoxysilane compound, a polymerizable functional group capable of reacting with the above polymerizable monomer, and an alkylene group connecting them.

[0025] The polymerizable functional group represented by Y in general formula (3) typically contains an ethylenically unsaturated bond. Examples of the polymerizable functional group represented by Y in 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 preferable. In one embodiment, the linking compound is a (meth)acryloyloxy group-containing alkoxysilane represented by the following general formula (3-1): (In general formula (3-1), R ４ and R ５ R each independently represents an alkyl group having 1 to 6 carbon atoms. ６ represents an alkylene group. ７ represents a hydrogen atom or a methyl group, and m represents an integer of 0 to 2.

[0027] In each of the general formulas (3) and (3-1), R ４Examples of the alkyl group represented by the formula (1) include R １ In each of the general formulas (3) and (3-1), R ５ Examples of the alkyl group represented by the formula (1) include R １ 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), R ６ Examples of the alkylene group represented by the formula (I) include alkylene groups having 1 to 10 carbon atoms, preferably alkylene groups having 1 to 6 carbon atoms, more preferably alkylene groups having 1 to 3 carbon atoms, and particularly preferably a propylene group.

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

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

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

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

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

[0034] E-1. Step of Preparing Siloxane Oligomer In the step of preparing a siloxane oligomer, typically, the above-described alkoxysilane compound is first mixed with a polar solvent to prepare an alkoxysilane solution. Examples of polar solvents include alcohols, ketones, and ethers, and alcohols are preferred. The polar solvents may 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 polar solvent described above. Examples of the acid component include hydrochloric acid, sulfuric acid, and nitric acid, and hydrochloric acid is preferred. The acid component concentration in the acidic solution is, for example, 0.5% by mass to 2.0% by mass.

[0036] The first mixture is then stirred for a period of time ranging from 1 to 10 hours, preferably from 4 to 8 hours. The temperature of the first mixture during stirring is, for example, from 0°C to 100°C, preferably from 20°C to 60°C.

[0037] This hydrolysis of the alkoxysilyl groups of the alkoxysilane compound produces silanol groups, which then undergo polycondensation reactions between the silanol groups themselves and / or between the silanol groups and the ethoxysilyl groups, resulting in the production of a siloxane oligomer having a first structural unit derived from the alkoxysilane compound and having silanol groups remaining at the molecular terminals.

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

[0039] E-2. Step of Preparing a Copolymer In the step of preparing a copolymer, typically, the linking compound and the polymerizable monomer are first mixed so that the second structural unit and the third structural unit are in the molar ratio described above to prepare a second mixed solution. A polymerization initiator is then added to the second mixed solution and stirred. The polymerization initiator can be selected arbitrarily and appropriately depending on the polymerizable functional groups possessed by the linking compound and the polymerizable monomer. A typical example of the polymerization initiator is a radical polymerization initiator. Examples of radical polymerization initiators include azo compounds such as 2,2'-azobisisobutyronitrile (AIBN) and peroxides such as benzoyl peroxide (BPO). The radical polymerization initiators can be used alone or in combination. Among the radical polymerization initiators, azo compounds are preferred, and AIBN is more preferred.

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

[0041] This causes the polymerizable functional groups (X) of the polymerizable monomers to polymerize with each other and also causes the polymerizable functional groups (X) of the polymerizable monomers to polymerize with the polymerizable functional group (Y) of the linking compound, resulting in the production of a copolymer having a second structural unit derived from the polymerizable monomer and a third structural unit derived from the linking compound.

[0042] In one embodiment, the second raw material liquid is prepared by dissolving the copolymer in the polar solvent. The polar solvent is preferably a ketone, more preferably methyl ethyl ketone (MEK).

[0043] E-3. Reaction Process of Siloxane Oligomer and Copolymer In the reaction process of the siloxane oligomer and copolymer, the siloxane oligomer and the copolymer are typically subjected to a sol-gel reaction. In one embodiment, a first source liquid containing a siloxane oligomer and a second source liquid containing a copolymer are mixed so that the first structural unit to the third structural unit are in the above-mentioned molar ratio to prepare a third mixed liquid in a sol state. As a result, the silanol residues of the siloxane oligomer and the alkoxysilyl groups of the copolymer react over time to prepare a pattern-forming material in a gel state.

[0044] E-4. Modification of the Method for Producing a Pattern-Forming Material The method for producing a pattern-forming material is not limited to the above-described embodiment. In another embodiment, the method for producing a pattern-forming material includes the steps of polycondensing the above-described alkoxysilane compound and the above-described linking compound to prepare a copolymer, polymerizing the above-described polymerizable monomer to prepare an oligomer, and reacting the copolymer with the oligomer to obtain a pattern-forming material. This method also allows the production of a pattern-forming material.

[0045] F. Method of Using the Pattern Formation Material The pattern formation material is typically used by dissolving it in an organic solvent. That is, the pattern formation material can be used in the form of a solution in which the pattern formation material is dissolved in an organic solvent (hereinafter referred to as a pattern formation material solution). The pattern formation material solution contains the above-described pattern formation material and an organic solvent. The pattern formation material solution is typically an organic solvent solution of the pattern formation material. The organic solvent is capable of dissolving the pattern formation material. Examples of organic solvents include polypropylene glycol monoethyl ether acetate, polypropylene glycol monoethyl ether, methyl amyl ketone, ethyl lactate, ethoxyethyl propionate, and methoxymethyl propionate, and preferred examples include polypropylene glycol monoethyl ether acetate, methyl amyl ketone, and ethyl lactate.

[0046] The pattern formation material solution may further contain any appropriate additives. Examples of additives include surfactants and adhesion promoters. The additives may be used alone or in combination.

[0047] G. Semiconductor Film Etching Method (Method for Producing Semiconductor Film Having Etched Portion) Next, a semiconductor film etching method using the above-described pattern formation material solution will be described with reference to FIGS.

[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 made of any appropriate semiconductor material. Typical 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, or, for example, 0.5 μm to 1.5 μm.

[0049] Next, a coating film 1a is formed by applying a pattern formation material solution onto the semiconductor film 2. At this time, the second structural unit derived from the polymerizable monomer represented by the general formula (2) above migrates toward the semiconductor film 2, and the first structural unit derived from the alkoxysilane compound represented by the general formula (1) above migrates toward the opposite side of the semiconductor film 2 (i.e., the surface side).

[0050] The coating film 1a is then dried under any appropriate conditions to form the functionally gradient material layer 1. In the functionally gradient material layer 1, the silicon (Si) content increases continuously from the semiconductor film 2 side toward the surface side, and the carbon (C) content increases continuously from the surface side toward the semiconductor film 2 side. The functionally gradient material layer 1 integrally has a carbon-rich portion located on the semiconductor film 2 side and a silicon-rich portion located on the opposite side of the carbon-rich portion from the semiconductor film 2.

[0051] The carbon-rich portion of the functionally gradient material layer 1 is typically in contact with the semiconductor film 2. The carbon-rich portion has a carbon atom content of, for example, 80% by mass or more, preferably 90% by mass or more, and more preferably 95% by mass or more. The upper limit of the carbon atom content in the carbon-rich portion is typically 100% by mass. The silicon atom content 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 functionally gradient material layer 1 is typically continuous with the carbon-rich portion. The silicon atom content in the silicon-rich portion is, for example, 25 mass% or more, preferably 30 mass% or more, and more preferably 40 mass% or more. The upper limit of the silicon atom content in the silicon-rich portion is typically 50 mass%. The carbon atom content in the silicon-rich portion is, for example, less than 75 mass%, preferably less than 70 mass%, and more preferably less than 60 mass%.

[0053] Next, as shown in Fig. 2, a resist film 3 having a predetermined pattern shape is formed on the functionally gradient material layer 1. Any appropriate method can be used to form the resist film. A representative method for forming the resist film is photolithography. The resist film 3 partially exposes the surface of the functionally gradient material layer 1. The surface portion of the functionally gradient material layer 1 exposed from the resist film 3 corresponds to the portion of the semiconductor film 2 to be etched.

[0054] Next, as shown in Figure 3, the functionally gradient material layer 1 is subjected to primary etching via the resist film 3. A typical primary etching method is reactive ion etching using halogen gas. At this time, in the functionally gradient material layer 1 exposed from the resist film 3, the silicon-rich portion is removed, but the carbon-rich portion is not. In other words, in the primary etching, only the silicon-rich portion of the functionally gradient material layer 1 is etched. As a result, a recess 11 is formed in the functionally gradient material layer 1. The bottom surface of the recess 11 is made up of the carbon-rich portion of the functionally gradient material layer 1.

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

[0056] 5, the portion of the semiconductor film 2 exposed from the opening 12 in the functionally gradient material layer 1 is tertiary etched. A typical example of the tertiary etching method is reactive ion etching using halogen gas. At this time, the silicon-rich portion of the functionally gradient material layer 1 and the portion of the semiconductor film 2 exposed from the opening 12 are removed. As a result, an etched portion 21 is formed at a desired position in the semiconductor film 2.

[0057] The etched portion 21 is typically a recess. The depth of the etched portion 21 (the dimension in the thickness direction of the semiconductor film 2) is adjusted arbitrarily and appropriately depending on the application of the semiconductor film 2. The depth of the etched 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 carbon-rich portion remaining on the semiconductor film 2 is removed. The method for removing the carbon-rich portion is not particularly limited. For example, reactive ion etching using oxygen gas can be used as a method for removing the carbon-rich portion. In this manner, the semiconductor film 2 having the etched portion 21 is manufactured.

[0059] The present invention will be specifically explained below with reference to examples, but the present invention is not limited to these examples.

[0060] Examples 1 to 9: An alkoxysilane solution was prepared by mixing tetraethoxysilane (TEOS, an alkoxysilane compound) and ethanol (a polar solvent). At room temperature (25°C), an acidic solution was added dropwise to the alkoxysilane solution while stirring. The acidic solution contained concentrated hydrochloric acid (an acid component), ethanol, and pure water. The hydrochloric acid concentration in the acidic solution was 1.2% by mass. The first mixture of the alkoxysilane solution and the acidic solution was then stirred for 5 hours. During this process, the ethoxysilyl groups of the TEOS were hydrolyzed to generate silanol groups, and the silanol groups and / or the silanol groups and the ethoxysilyl groups underwent polycondensation reactions. As a result, a siloxane oligomer having a first structural unit derived from TEOS was produced. The siloxane oligomer contained silanol residues. This resulted in a first raw material solution containing the siloxane oligomer. Thereafter, hydrochloric acid, ethanol, and water were removed from the first raw material liquid by known means.

[0061] A second mixed solution was prepared by mixing 3-methacryloxypropyltrimethoxysilane (MP silane, linking compound) and styrene (polymerizable monomer) in the molar ratio shown in Table 1. The carbon atom content in the polymerizable monomer (= sum of atomic weights of carbon atoms contained in the polymerizable monomer, C, / molecular weight of polymerizable monomer, Mw × 100) is also shown in Table 1. Next, 2,2'-azobisisobutyronitrile (AIBN, radical polymerization initiator) was added to the second mixed solution, followed by stirring at 75°C for 3 hours. This resulted in radical polymerization of the oxymethacryloyl group of the MP silane (linking compound) and the vinyl group of the styrene, preparing a copolymer. The copolymer contained a second structural unit derived from styrene and a third structural unit derived from the MP silane. The resulting copolymer was then dissolved in methyl ethyl ketone (MEK) to prepare a second raw material solution.

[0062] Next, the first and second source solutions were mixed so that the molar ratio of TEOS, MP-silane, and styrene was the value shown in Table 1 to prepare a third mixed solution in a sol state. The silanol residues of the siloxane oligomer and the ethoxysilyl groups of the copolymer underwent a polycondensation reaction over time, producing a gel-state pattern-forming material. 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 A first raw material liquid containing a siloxane oligomer was prepared in the same manner as in Example 1, and then 3-methacryloxypropyltrimethoxysilane (MP silane, linking compound) was added to the first raw material liquid so that the molar ratio of TEOS to MP silane was the value shown 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) to styrene (polymerizable monomer) was changed to the value shown in Table 1, and the copolymer was used as a pattern-forming material.

[0065] Examples 10 to 13 and Comparative Example 3 Pattern-forming materials were 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 compounds.

[0067] <Evaluation of Etching Depth> Semiconductor films were etched using the pattern-forming materials obtained in the Examples and Comparative Examples. Specifically, the pattern-forming materials obtained in the Examples and Comparative Examples were dissolved in propylene glycol monoethyl acetate (an organic solvent) to prepare pattern-forming material solutions. A silicon substrate having a 1.0 μm-thick oxide film as a semiconductor film was also prepared. Next, the pattern-forming material solution was applied onto the thermally oxidized film, and the coating was dried by heating. This resulted in the formation of a functionally gradient material layer on the oxide film. The functionally gradient material layer integrally comprised 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 any suitable pattern was formed on the functionally gradient material layer, with the resist film having the pattern partially exposing the functionally gradient material layer.

[0069] Next, the functionally gradient material layer was primarily etched through the resist film by reactive ion etching using halogen gas. As a result, only the silicon-rich portions exposed from the resist film were etched, forming recesses in the functionally gradient material layer (see Figure 3). The recesses exposed the carbon-rich portions.

[0070] Then, the resist film and the carbon-rich portion of the functionally gradient material layer were subjected to secondary etching by reactive ion etching using oxygen gas. This removed the resist film and the carbon-rich portion exposed from the recess. As a result, an opening was formed in the functionally gradient material layer that partially exposed the semiconductor film (see FIG. 4).

[0071] Next, a portion of the semiconductor film exposed from the opening in the functionally gradient material layer was tertiarily etched by reactive ion etching using halogen gas. This removed the silicon-rich portion of the functionally gradient material layer and the semiconductor film (oxide film) exposed from the opening, forming an etched portion in the semiconductor film (oxide film) (see Figure 5). After that, the carbon-rich portion remaining on the semiconductor film was removed by reactive ion etching using oxygen gas.

[0072] This completed the etching of the semiconductor film. 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. ⊚: Etching depth of 0.55 μm or more; ◯: Etching depth of 0.40 μm or more but less than 0.55 μm; △: Etching depth of 0.10 μm or more but less than 0.40 μm; ×: Etching depth less than 0.10 μm.

[0073]

[0074]

[0075] <Evaluation> As is clear from Tables 1 and 2, when the content of carbon atoms in the polymerizable monomer is 70 mass % or more, a functionally gradient material layer can be smoothly formed on a semiconductor film by applying a pattern formation material solution containing the pattern formation material onto the semiconductor film. Therefore, etching of the semiconductor film can be carried out more smoothly than with the multilayer resist method.

[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 etching semiconductor films.

[0077] REFERENCE SIGNS LIST 1 Functionally gradient material layer 2 Semiconductor film 3 Resist film 4 Semiconductor substrate

Claims

1. A pattern-forming material comprising: 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 being bonded to the first structural unit and the second structural unit, wherein the polymerizable monomer has a carbon atom content of 70 mass% or more: (In general formula (1), R １ and R ２ each independently represents an alkyl group having 1 to 6 carbon atoms; and n represents an integer of 0 to 2; (In general formula (2), R ３ represents a monovalent organic group; X represents a polymerizable functional group; (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 capable of polymerizing with X in the general formula (2); and m represents an integer of 0 to 2.

2. A pattern forming material as described in claim 1, wherein the content ratio of the first structural unit is 35 moles or more and 85 moles or less per mole of the third structural unit, and the content ratio of the second structural unit is 15 moles or more and 65 moles or less per mole of the third structural unit.

3. A pattern forming material as described in claim 1, wherein the content ratio of the first structural unit is 45 moles or more and 75 moles or less per mole of the third structural unit, and the content ratio of the second structural unit is 25 moles or more and 55 moles or less per mole of the third structural unit.

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

5. In the above general formula (2), R ３ 4. The pattern forming material according to claim 1, wherein the organic group represented by the formula: is an aryl group.

6. In the above general formula (2), R ３ 6. The pattern forming material according to claim 5, wherein the organic group represented by the formula: 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), which has a carbon atom content of 70 mass % or more, and a linking compound represented by the following general formula (3): (In general formula (1), R １ and R ２ each independently represents an alkyl group having 1 to 6 carbon atoms; and n represents an integer of 0 to 2; (In general formula (2), R ３ represents a monovalent organic group; X represents a polymerizable functional group; (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 capable of polymerizing with X in the general formula (2); and m represents an integer of 0 to 2.

Images