WO2018179704A1 - Pattern forming method - Google Patents

Abstract

This pattern forming method comprises: a step for applying a composition for underlayer film formation to a substrate; a step for applying a radiation sensitive composition for resist film formation directly or indirectly to an underlayer film which is formed by the step for applying a composition for underlayer film formation; a step for exposing a resist film to light, said resist film being formed by the step for applying a radiation sensitive composition for resist film formation; and a step for developing the resist film which has been exposed to light. The composition for underlayer film formation contains at least one of: a first component which produces a component having an acid group that is a sulfo group, a carboxy group, a phosphono group, a phosphoric acid group, a sulfuric acid group, a sulfone amide group, a sulfonyl imide group, a -CRF1RF2OH group or a combination of these groups by the action of heat; and a second component which is other than the first component and has one of the acid groups described above. The radiation sensitive composition for resist film formation contains 50% by mass or more of a metal-containing compound in terms of solid content.

Description

Pattern formation method

The present invention relates to a pattern forming method.

In a general pattern forming method used for microfabrication by lithography, a resist film formed from a radiation-sensitive composition for forming a resist film is treated with deep ultraviolet light (for example, ArF excimer laser light, KrF excimer laser light, etc.), extreme ultraviolet light ( The exposed portion is exposed to an electromagnetic wave such as EUV) or a charged particle beam such as an electron beam to generate an acid at the exposed portion. Then, a chemical reaction using this acid as a catalyst causes a difference in the dissolution rate with respect to the developer in the exposed area and the unexposed area, thereby forming a pattern on the substrate. The formed pattern can be used as a mask or the like in substrate processing.

Such a pattern forming method is required to improve the resist performance as the processing technology becomes finer. In response to this requirement, the types of organic polymers, acid generators and other components used in the radiation-sensitive composition for resist film formation, the molecular structure, and the like have been studied, and further their combinations have been studied in detail ( (See JP-A-11-125907, JP-A-8-146610, and JP-A-2000-298347). In addition, the use of a radiation-sensitive composition for forming a resist film containing a metal-containing compound instead of an organic polymer has been studied.

JP-A-11-125907 JP-A-8-146610 JP 2000-298347 A

However, in the pattern formed by the pattern forming method using the above-described metal-containing compound, resist shape abnormalities (poisoning) such as pattern tailing and wide area damage in which a scum is generated in a space portion in a wide range occur. Sometimes. This poisoning becomes particularly noticeable when a pattern is formed on a substrate having a low dielectric constant insulating film formed of porous silica or the like. The reason for this poisoning is that, for example, an amine such as ammonia used for cleaning the substrate is adsorbed on the low dielectric constant insulating film or the like, and this amine is released from the substrate during pattern formation and contaminates the resist film. It is believed that.

The present invention has been made based on the above circumstances, and an object of the present invention is to provide a pattern forming method having excellent poisoning suppression properties.

The invention made in order to solve the above-mentioned problems includes a step of applying a composition for forming an underlayer film on a substrate, and a resist directly or indirectly on an underlayer film formed by the above-described composition application process for forming an underlayer film. A step of applying the radiation-sensitive composition for film formation, a step of exposing the resist film formed by the radiation-sensitive composition application step for forming the resist film, and a step of developing the exposed resist film And the composition for forming an underlayer film comprises a sulfo group, a carboxy group, a phosphono group, a phosphoric acid group, a sulfuric acid group, a sulfonamide group, a sulfonylimide group, —CR ^F1 R ^F2 OH (R ^F1 is a fluorine atom) or a fluorinated alkyl group .R ^F2 is a hydrogen atom, a fluorine atom or a fluorinated alkyl group.) or the first to the component having an acid group which is a combination thereof produced by the action of heat And at least one component other than the first component and the second component having the acid group, and the radiation-sensitive composition for forming a resist film converts the metal-containing compound to a solid content Is a pattern forming method containing 50% by mass or more.

Here, the “acid group” refers to a group containing a hydrogen atom that can dissociate as a proton.

According to the pattern forming method of the present invention, poisoning such as pattern tailing and wide area damage can be suppressed. Therefore, this pattern forming method can be suitably used for a semiconductor device processing process and the like that are expected to be further miniaturized in the future.

<Pattern formation method>
The pattern forming method includes a step of applying a composition for forming an underlayer film on a substrate (a composition applying step for forming an underlayer film) and an underlayer film formed by the above-described composition applying step for forming an underlayer film The resist film-forming radiation-sensitive composition is applied directly or indirectly (resist-film-forming radiation-sensitive composition coating process) and the resist film-forming radiation-sensitive composition coating process. A step of exposing the resist film (exposure step) and a step of developing the exposed resist film (development step). The composition for forming the lower layer film includes a sulfo group, a carboxy group, a phosphono group, a phosphoric acid group, a sulfuric acid group, a sulfonamide group, a sulfonylimide group, —CR ^F1 R ^F2 OH (R ^F1 is a fluorine atom or a fluorinated alkyl group). R ^F2 is a hydrogen atom, a fluorine atom or a fluorinated alkyl group) or a combination thereof, which has an acid group (hereinafter also referred to as “acid group (a)”). And a second component (hereinafter referred to as “[A] thermal acid generating component”) and a component other than [A] thermal acid generating component and having an acid group (a). [B] also referred to as “acid group-containing component”). Moreover, the said radiation sensitive composition for resist film formation contains a metal containing compound (henceforth "[P] metal containing compound") 50 mass% or more in conversion of solid content.

The pattern forming method includes the above-described steps, and the composition for forming a lower layer film contains at least one of [A] a thermal acid generating component and [B] an acid group-containing component, Poisoning can be suppressed because a radiation composition contains [P] metal containing compound 50 mass% or more in conversion of solid content. The reason why the pattern forming method has the above-described configuration provides the above-mentioned effect is not necessarily clear, but can be estimated as follows, for example. That is, in the pattern forming method, the [P] metal-containing compound or the like absorbs exposure light and emits secondary electrons in the exposed portion of the resist film, and the secondary electrons form the structure or the like of the [P] metal-containing compound. It is considered that the pattern can be formed because the solubility in the developer increases or decreases by changing. Here, since the lower layer film in the pattern forming method includes a component having an acid group (a) generated from the thermal acid generating component [A] and / or a component containing [B] acid group at the time of film formation, By these components, amine liberated from the substrate can be trapped by the lower layer film, and contamination of the resist film can be suppressed. As a result, the pattern formation method is considered to be excellent in poisoning suppression because the amine does not easily affect the structural change of the [P] metal-containing compound.

Hereinafter, for the pattern formation method, the underlayer film forming composition used in the underlayer film forming composition coating process and the resist film forming radiation sensitive composition used in the resist film forming radiation sensitive composition coating process Then, the details of each step will be described.

[Composition for forming lower layer film]
The composition for forming an underlayer film contains at least one of [A] a thermal acid generating component and [B] an acid group-containing component. From the viewpoint of storage stability, the lower layer film-forming composition preferably contains only the [A] thermal acid generating component among the [A] thermal acid generating component and the [B] acid group-containing component. [A] The thermal acid generating component and the [B] acid group-containing component may each be a low molecular compound or an organic polymer. Hereinafter, among the [A] thermal acid generating component and the [B] acid group-containing component, the low-molecular compounds are referred to as [A1] thermal acid generator and [B1] acid group-containing compound, respectively, and the organic polymers are respectively [A2]. ] Thermal acid generating polymer and [B2] acid group-containing polymer. Here, the low molecular compound means a compound having a molecular weight of 1,500 or less. “Organic polymer” refers to a polymer in which the main chain contains carbon atoms, and “inorganic polymer” refers to a polymer in which the main chain does not contain carbon atoms.

The composition for forming the lower layer film includes [A2] thermal acid generating polymer, [B2] acid group-containing polymer, and [A] third organic polymer other than the thermal acid generating component and [B] acid group-containing component ( Hereinafter, it is preferable to contain at least one organic polymer component among “[C1] organic polymer”). Moreover, the composition for lower layer film formation may further contain a [C2] inorganic polymer, a [C3] aromatic ring-containing compound, a [D] additive, a [E] solvent, and the like. In addition, the [A] to [E] components in the composition for forming an underlayer film can be used singly or in combination of two or more.

The upper limit of the weight average molecular weight of the organic polymer component is preferably 100,000, and more preferably 30,000. Here, Mw in this specification and the number average molecular weight (Mn) described later are values measured by gel permeation chromatography (GPC) under the following conditions.
GPC column: For example, two “G2000HXL”, one “G3000HXL” and one “G4000HXL” manufactured by Tosoh Corporation Column temperature: 40 ° C.
Elution solvent: Tetrahydrofuran Flow rate: 1.0 mL / min Sample concentration: 1.0% by mass
Sample injection volume: 100 μL
Detector: Differential refractometer Standard material: Monodisperse polystyrene

The organic polymer component is preferably an organic polymer component having an aromatic ring from the viewpoint of improving heat resistance and etching resistance, more preferably an organic polymer component having an aromatic ring in the main chain, and obtained by polycondensation. An organic polymer component having an aromatic ring in the main chain is more preferable.

As the aromatic ring, for example, an aromatic carbon ring such as a benzene ring, naphthalene ring, anthracene ring, indene ring, pyrene ring, fluorenylidene biphenyl ring, fluorenylidene binaphthalene ring, furan ring, pyrrole ring, thiophene ring, Examples include phosphole ring, pyrazole ring, oxazole ring, isoxazole ring, thiazole ring, pyridine ring, pyrazine ring, pyrimidine ring, pyridazine ring and triazine ring.

Examples of the fluorinated alkyl group represented by R ^F1 and R ^F2 in the acid group (a) include a fluorinated alkyl group having 1 to 20 carbon atoms, and among these, a perfluoroalkyl group is preferable, A trifluoromethyl group is more preferred.

The acid group (a) is preferably a sulfo group. As described above, by using a sulfo group in which protons are relatively easily dissociated as the acid group (a), the amine can be trapped more effectively by the lower layer film.

[A] The upper limit of the acid dissociation index (pKa) of the component generated from the thermal acid generating component and [B] the acid group-containing component is preferably 3, and more preferably 2. On the other hand, the lower limit of Ka is preferably −15, more preferably −10. Thus, by setting the pKa in the above range, that is, [A] the acidity of the component generated from the thermal acid generating component, and [B] the acidity of the acid group-containing component are relatively high, The amine can be trapped more effectively. Here, pKa in the present specification is a value measured by ACD / ChemSketch (ACD / Labs 8.00 Release Product Version: 8.08). Mean value.

([A] Thermal acid generating component)
[A] The thermal acid generating component generates a component having an acid group (a) by the action of heat. In the pattern formation method, the lower layer film-forming composition contains [A] a thermal acid generating component, so that the acid group (a) is added to the lower layer film during prebaking or the like in the lower layer film-forming composition coating step described later. The component which has is generated. As a result, even if the amine is released from the substrate, the amine can be trapped by the component having the acid group (a) in the lower layer film, so that poisoning can be suppressed. [A] As a thermal acid generation component, [A1] a thermal acid generator is preferable.

[[A1] Thermal acid generator]
[A1] The thermal acid generator is a low molecular compound that generates a component having an acid group (a) by the action of heat.

[A1] The component generated from the thermal acid generator is preferably a sulfonic acid, more preferably a fluorinated alkylsulfonic acid having 1 to 10 carbon atoms and a sulfonic acid having an alicyclic structure, a perfluoroalkylsulfonic acid and 10- Camphorsulfonic acid is more preferable, and trifluoromethanesulfonic acid, nonafluorobutanesulfonic acid and 10-camphorsulfonic acid are particularly preferable.

[A1] Thermal acid generators include, for example, onium salt compounds such as iodonium salt compounds, organic sulfonic acid alkyl esters, 2,4,4,6-tetrabromocyclohexadienone, benzoin tosylate, 2-nitrobenzyl tosylate Etc.

Examples of the iodonium salt compound include anions such as trifluoromethanesulfonate, nonafluoro-n-butanesulfonate, 10-camphorsulfonate, pyrenesulfonate, n-dodecylbenzenesulfonate, naphthalenesulfonate, diphenyliodonium, bis (4-t-butylphenyl). ) Salt compounds with iodonium cations such as iodonium.

[A1] The thermal acid generator is preferably an onium salt compound, more preferably an iodonium salt compound, and bis (4-t-butylphenyl) iodonium trifluoromethanesulfonate, nonafluoro-n-butanesulfonate and bis (4-t- More preferred is butylphenyl) iodonium 10-camphorsulfonate.

When the lower layer film-forming composition contains [A1] a thermal acid generator, the lower limit of the content of the [A1] thermal acid generator in the solid film conversion composition in terms of solid content is 0.5 mass. % Is preferable, 3% by mass is more preferable, and 7% by mass is more preferable. On the other hand, the upper limit of the content is preferably 40% by mass, more preferably 25% by mass, and even more preferably 15% by mass. [A1] By setting the content of the thermal acid generator in terms of solid content in the above range, amine can be trapped more effectively by the lower layer film. Here, the “solid content” in the composition for forming a lower layer film refers to components other than the [E] solvent described later.

[[A2] Thermal acid generating polymer]
[A2] The thermal acid generating polymer is an organic polymer that generates a component having an acid group (a) by the action of heat. [A2] The component generated from the thermal acid generating polymer may be a low molecular compound having an acid group (a) or an organic polymer having an acid group (a). ) Is preferred.

[A2] The lower limit of Mw of the thermal acid generating polymer is preferably 1,600, more preferably 2,000, and further preferably 2,500. On the other hand, the upper limit of Mw is preferably 50,000, more preferably 30,000, and further preferably 15,000.

[A2] Examples of the thermal acid generating polymer include a polymer having a structural unit in which one or more [A1] thermal acid generators are incorporated, and a structural unit having an alkoxysulfonyl group is preferable. Examples of the alkoxysulfonyl group include an alkoxysulfonyl group having 1 to 20 carbon atoms, and an ethoxysulfonyl group is preferable. As the structural unit containing an alkoxysulfonyl group, a styrene-based structural unit containing an aromatic ring substituted with an alkoxysulfonyl group is preferable, and a structural unit represented by the following formula is more preferable. In addition, the [A2] thermal acid generating polymer may have other structural units other than the structural unit in which the [A1] thermal acid generator is incorporated.

In the above formula, R ¹ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. A is a divalent hydrocarbon group composed of a single bond, an alkylene group having 1 to 10 carbon atoms, a cycloalkylene group having 4 to 20 carbon atoms, an arylene group having 6 to 20 carbon atoms, or a combination thereof. R ² is an alkyl group having 1 to 20 carbon atoms.

[A2] The lower limit of the content ratio of the structural unit in which the [A1] thermal acid generator is incorporated in all the structural units constituting the thermal acid generating polymer is preferably 1 mol%, and more preferably 5 mol%. On the other hand, as an upper limit of the content rate of the said structural unit, 80 mol% is preferable and 60 mol% is more preferable. By setting the content ratio of the structural unit in the above range, the amine can be trapped more effectively by the lower layer film.

[A2] The thermal acid generating polymer may have a structural unit other than the structural unit in which the [A1] thermal acid generator is incorporated. The structural unit is not particularly limited, and examples thereof include those similar to the structural unit constituting each resin in the [C1] organic polymer to be described later. Among these, derived from a compound having an acenaphthylene skeleton. The structural unit derived from acenaphthylene and the structural unit derived from hydroxymethylacenaphthylene are more preferable.

[A2] The lower limit of the content ratio of the other structural units in all the structural units constituting the thermal acid-generating polymer is preferably 5 mol%, and more preferably 10 mol%. On the other hand, as an upper limit of the content rate of the said structural unit, 80 mol% is preferable and 50 mol% is more preferable.

When the composition for lower layer film formation contains [A2] thermal acid generation polymer, as a minimum of content in conversion of solid content of [A2] thermal acid generation polymer in the composition for lower layer film formation, it is 80 mass. % Is preferable, 90% by mass is more preferable, and 95% by mass is more preferable. Moreover, 100 mass% may be sufficient as content in conversion of solid content of [A2] thermal acid generation polymer. [A2] By setting the content of the thermal acid-generating polymer in terms of solid content to be equal to or higher than the above lower limit, amine can be trapped more effectively by the lower layer film.

([B] acid group-containing component)
[B] The acid group-containing component is a component having an acid group (a). In the pattern formation method, even if the amine is liberated from the substrate because the composition for forming the lower layer film contains the [B] acid group-containing component, the amine is released by the [B] acid group-containing component in the lower layer film. Since it can be trapped, poisoning can be suppressed. [B] The acid group-containing component is preferably a [B2] acid group-containing polymer.

[[B1] acid group-containing compound]
[B1] The acid group-containing compound is a low molecular compound having an acid group (a). [B1] Specific examples of the acid group-containing compound include, for example, the same compounds as those having the acid group (a) generated from the above-described [A1] thermal acid generator.

When the composition for forming a lower layer film contains a [B1] acid group-containing compound, the content of the [B1] acid group-containing compound in the composition for forming a lower layer film is, for example, the above-described [A1] thermal acid generator It can be the same as that of suitable content.

[[B2] acid group-containing polymer]
[B2] The acid group-containing polymer is an organic polymer having an acid group (a). [B2] Examples of the acid group-containing polymer include ion exchange resins having a structural unit containing an acid group (a).

[B2] The lower limit of the Mw of the acid group-containing polymer is preferably 1,600, more preferably 2,000, and even more preferably 2,500. On the other hand, the upper limit of Mw is preferably 50,000, more preferably 30,000, and further preferably 15,000.

Examples of the ion exchange resin include a polymer obtained by introducing an acid group (a) into an organic polymer such as a styrene polymer, a (meth) acrylic polymer, a polyester polymer, cellulose, or polytetrafluoroethylene. It is done. More specifically, a polymer obtained by sulfonating a novolak resin, a polymer obtained by sulfonating a resol resin, a polymer obtained by sulfonating a styrene polymer cross-linked with divinylbenzene, and cross-linked with divinylbenzene (meth) Examples thereof include a polymer obtained by carboxylating an acrylic polymer. Examples of the novolak resin and resol resin that are sulfonated in the ion exchange resin include those similar to the novolak resin and resol resin in [C1] organic polymer described later.

As the structural unit containing an acid group (a), those in which a sulfo group is introduced into the structural unit of the novolak resin are preferable. Examples of such a structural unit include a structural unit represented by the following formula.

[B2] The lower limit of the content ratio of the structural unit containing the acid group (a) in all the structural units constituting the acid group-containing polymer is preferably 5 mol%, and more preferably 10 mol%. On the other hand, as an upper limit of the content rate of the said structural unit, 80 mol% is preferable and 50 mol% is more preferable. By setting the content ratio of the structural unit in the above range, the amine can be trapped more effectively by the lower layer film.

[B2] The lower limit of the content ratio of the structural unit not containing the acid group (a) in all the structural units constituting the acid group-containing polymer is preferably 5 mol%, and more preferably 10 mol%. On the other hand, as an upper limit of the content rate of the said structural unit, 80 mol% is preferable and 50 mol% is more preferable.

When the composition for forming the lower layer film contains the [B2] acid group-containing polymer, the lower limit of the content of the [B2] acid group-containing polymer in the composition for forming the lower layer film in terms of solid content is 80 mass. % Is preferable, 90% by mass is more preferable, and 95% by mass is more preferable. Moreover, 100 mass% may be sufficient as content in conversion of solid content of a [B2] acid group containing polymer. [B2] By setting the content of the acid group-containing polymer in terms of solid content to be the above lower limit or more, amine can be trapped more effectively by the lower layer film.

([C1] organic polymer)
[C1] The organic polymer is an organic polymer other than [A] a thermal acid generating component and [B] an acid group-containing component. [C1] As the organic polymer, for example, those described in paragraphs [0040] to [0116] of JP-A-2016-206676 can be used, but from the viewpoint of further improving the etching resistance of the lower layer film, Novolac resins, resol resins, aromatic ring-containing vinyl resins, acenaphthylene resins, indene resins, polyarylene resins, triazine resins, calixarene resins, fullerene resins and pyrene resins are preferred, novolak resins And acenaphthylene resins are more preferred.

As the lower limit of Mw of novolak resin, resol resin, aromatic ring-containing vinyl resin, acenaphthylene resin, indene resin, polyarylene resin, triazine resin, fullerene resin or pyrene resin, 500 is preferable, 1,000 is more preferred, and 2,000 is even more preferred. On the other hand, the upper limit of Mw is preferably 10,000. The lower limit of the ratio of Mw to Mn (Mw / Mn) of these resins is preferably 1.1. On the other hand, the upper limit of the Mw / Mn is preferably 5, more preferably 3, and even more preferably 2. By setting the Mw and Mw / Mn within the above ranges, the flatness and surface coatability of the lower layer film can be improved.

The lower limit of the molecular weight of the calixarene resin is preferably 500, more preferably 700, and even more preferably 1,000 from the viewpoint of improving the flatness of the resist underlayer film. The upper limit of the molecular weight is preferably 5,000, more preferably 3,000, and further preferably 1,500. When the calixarene resin has a molecular weight distribution, the molecular weight of the calixarene resin means Mw in terms of polystyrene by GPC.

([C2] inorganic polymer)
[C2] Examples of the inorganic polymer include [C2-1] polysiloxane, a plurality of metal atoms, an oxygen atom that bridges between the metal atoms (hereinafter also referred to as “bridged oxygen atom”), and the metal atom. And a [C2-2] complex (binuclear complex) containing a polydentate ligand coordinated to the.

[[C2-1] polysiloxane]
Examples of the [C2-1] polysiloxane include those having the structural unit (I) represented by the following formula (I) and / or the structural unit (II) represented by the following formula (II). . [C2-1] Each structural unit in the polysiloxane can be used alone or in combination of two or more.

In the above formula (I), R ^X1 is a monovalent organic group having 1 to 20 carbon atoms.

Here, “organic group” refers to a group having at least one carbon atom.

Examples of the monovalent organic group represented by R ^X1 include a monovalent hydrocarbon group, a monovalent fluorinated hydrocarbon group, and a divalent heteroatom-containing group between carbon and carbon of the monovalent hydrocarbon group. And a monovalent chain hydrocarbon group, a monovalent aromatic hydrocarbon group, a monovalent fluorinated aromatic hydrocarbon group, and a group containing a heterocyclic ring are more preferred. , An alkyl group, an aryl group, a fluoroaryl group and a group containing a nitrogen-containing heterocyclic ring are more preferred. Examples of the nitrogen-containing heterocycle include an azocycloalkane ring and an isocyanuric ring.

Examples of the structural unit (I) include a structural unit represented by the following formula.

[C2-1] The lower limit of the content ratio of the structural unit (I) in the polysiloxane is preferably 1 mol%, and more preferably 5 mol%. On the other hand, as an upper limit of the content rate of structural unit (I), 60 mol% is preferable and 40 mol% is more preferable.

[C2-1] The lower limit of the content ratio of the structural unit (II) in the polysiloxane is preferably 40 mol%, more preferably 60 mol%. On the other hand, as an upper limit of the content rate of structural unit (II), 99 mol% is preferable and 95 mol% is more preferable.

The lower limit of Mw of [C2-1] polysiloxane is preferably 500, more preferably 800, and further preferably 1,200. On the other hand, the upper limit of the Mw is preferably 100,000, more preferably 30,000, still more preferably 10,000, and particularly preferably 5,000.

[[C2-2] complex]
The metal atom in the [C2-2] complex is preferably titanium, tantalum, zirconium and tungsten (hereinafter also referred to as “specific metal atom”), more preferably titanium and zirconium. By using these metal atoms, the pattern formability in the pattern forming method and the etching selectivity of the resist film and the lower layer film can be improved. These metal atoms can be used singly or in combination of two or more. However, in order to ensure in-plane uniformity of the etching rate of the lower layer film in the nanometer order during etching, one kind alone. It is preferable to use it.

When the [C2-2] complex contains a bridging oxygen atom, it can be a stable binuclear complex, and as a result, the pattern forming property and etching selectivity in the pattern forming method are improved. A plurality of bridging oxygen atoms are preferably bonded to one metal atom, but some of the metal atoms may be bonded to one metal atom. [C2-2] The complex preferably mainly contains a structure in which two bridging oxygen atoms are bonded to one metal atom. Since the [C2-2] complex mainly contains such a structure, a straight chain represented by -M ¹ -OM ¹ -O- (M ¹ is a metal atom such as a specific metal atom) It becomes possible to take a structure close to the shape, and the solubility is improved. As a result, the removability when removing the lower layer film using the cleaning solvent (hereinafter, also referred to as “removability of the lower layer film”) is improved. Here, “mainly containing” the above structure means that 50 mol% or more, preferably 70 mol% or more, more preferably 90 mol% or more, particularly preferably 90% by mol or more of all metal atoms constituting the [C2-2] complex. It means that two bridging oxygen atoms are bonded to each other with respect to 95 mol% or more of metal atoms.

The [C2-2] complex may have other bridging ligands such as a peroxide ligand (—O—O—) in addition to the bridging oxygen atom.

The multidentate ligand in the [C2-2] complex improves the solubility of the [C2-2] complex, thereby improving the removability of the lower layer film. Examples of the polydentate ligand include hydroxy acid ester, β-diketone, β-keto ester, malonic acid diester optionally substituted at the α-position carbon atom (hereinafter also referred to as “malonic acid diesters”), and π A hydrocarbon having a bond or a ligand derived from these compounds is preferred. By using a multidentate ligand as the above ligand, the removability of the lower layer film can be further improved. These compounds usually form a polydentate ligand as an anion obtained by obtaining one electron, form a polydentate ligand as an anion from which a proton is eliminated, or have a structure as it is. Forms a bidentate ligand.

The lower limit of the molar ratio of the polydentate ligand to the metal atom in the [C2-2] complex (polydentate ligand / metal atom) is preferably 1, more preferably 1.5, and even more preferably 1.8. . On the other hand, the upper limit of the ratio is preferably 3, more preferably 2.5, and even more preferably 2.2.

The [C2-2] complex may contain other ligands in addition to the above-mentioned bridging ligand and multidentate ligand.

The lower limit of the absolute molecular weight of the [C2-2] complex measured by the static light scattering method is preferably 400, more preferably 1,200, and even more preferably 2,000. The upper limit of the absolute molecular weight is preferably 50,000, more preferably 20,000, still more preferably 10,000, and particularly preferably 5,000. By setting the absolute molecular weight within the above range, the removability of the lower layer film can be further improved, and volatilization of the [C2-2] complex during the formation of the lower layer film can be suppressed.

The absolute molecular weight of the [C2-2] complex by the static light scattering method is a value measured under the following conditions.
Apparatus: Light scattering measurement apparatus (for example, “ALV-5000” of ALV Germany)
Measurement concentration: 2.5 mass%, 5.0 mass%, 7.5 mass%, 10.0 mass%, 4 points Standard liquid: Toluene Measurement temperature: 23 ° C
The refractive index of the solution and the density of the solution necessary for calculating the absolute molecular weight are values measured by the following apparatus.
Measuring device for refractive index of solution: refractometer (for example, “RA-500” of Kyoto Electronics Co., Ltd.)
Solution density measuring device: Density / specific gravity meter (for example, “DA-100” manufactured by Kyoto Electronics Industry Co., Ltd.)
In addition, in the measurement of absolute molecular weight using the above-mentioned manufacturer and model number apparatus, a method of setting a sample solution in a quartz cell is used, but in addition, a multi-angle laser light scattering detector for injecting a sample solution into a flow cell A method using (MALLS) may be used.

([C3] aromatic ring-containing compound)
[C3] The aromatic ring-containing compound is a compound having an aromatic ring and having a molecular weight of 600 or more and 3,000 or less. [C3] When the aromatic ring-containing compound has a molecular weight distribution, the molecular weight of the [C3] aromatic ring-containing compound means, for example, a weight average molecular weight (Mw) in terms of polystyrene by GPC. When the composition for forming the lower layer film contains the [C3] aromatic ring-containing compound, the heat resistance and etching resistance of the lower layer film can be improved as in the case of containing the [C1] organic polymer having an aromatic ring. [C3] Specific examples of the aromatic ring-containing compound include compounds described in paragraphs [0117] to [0179] of JP-A-2016-206676.

([D] additive)
[D] The additive improves various performances of the underlayer film forming composition. Examples of the [D] additive include [D1] cross-linking agent, [D2] cross-linking accelerator, surfactant, adhesion aid and the like. The composition for forming a lower layer film preferably further contains a [D1] crosslinking agent and / or a [D2] crosslinking accelerator.

[[D1] Crosslinking agent]
[D1] The cross-linking agent is a component that forms a cross-linking bond between [C1] organic polymers by the action of heat or the like. When the composition for forming a lower layer film contains [D1] a crosslinking agent, the hardness of the lower layer film can be improved.

[D1] Examples of the crosslinking agent include compounds having an alkoxyalkylated amino group, hydroxymethyl group-substituted phenol compounds, and the like.

Examples of the hydroxymethyl group-substituted phenol compound include 2-hydroxymethyl-4,6-dimethylphenol, 1,3,5-trihydroxymethylbenzene, 3,5-dihydroxymethyl-4-methoxytoluene [2,6-bis (Hydroxymethyl) -p-cresol], 4,4 '-(1- (4- (1- (4-hydroxy-3,5-bis (methoxymethyl) phenyl) -1-methylethyl) phenyl) ethylidene) Examples thereof include bis (2,6-bis (methoxymethyl) phenol), 5,5 ′-(1-methylethylidene) bis (2-hydroxy-1,3-benzenedimethanol), and the like.

Examples of the compound having an alkoxyalkylated amino group include plural compounds in one molecule such as (poly) methylolated melamine, (poly) methylolated glycoluril, (poly) methylolated benzoguanamine, (poly) methylolated urea, etc. Examples of the nitrogen-containing compound having an active methylol group include compounds in which at least a part of the hydrogen atom of the hydroxy group in the methylol group is substituted with an alkyl group such as a methyl group or a butyl group. The compound having an alkoxyalkylated amino group may be a mixture in which a plurality of substituted compounds are mixed, or may include an oligomer component that is partially self-condensed.

[D1] In addition to the compounds described above, for example, a polyfunctional (meth) acrylate compound, an epoxy compound, a hydroxymethyl group-substituted phenol compound, an alkoxyalkyl group-containing phenol compound, or the like can be used as the crosslinking agent. Specific examples of these compounds include compounds described in paragraphs [0203] to [0207] of JP-A-2016-206676.

[D1] As the crosslinking agent, a hydroxymethyl group-substituted phenol compound and a compound having an alkoxyalkylated amino group are preferable, and 5,5 ′-(1-methylethylidene) bis (2-hydroxy-1,3-benzene) Dimethanol) and 2,4,6-tris [bis (methoxymethyl) amino] -1,3,5-triazine are more preferred.

When the lower layer film-forming composition contains [D1] a crosslinking agent, the lower limit of the content of the [D1] crosslinking agent in the lower layer film-forming composition in terms of solid content is preferably 0.1% by mass, 0.5 mass% is more preferable, and 1.5 mass% is further more preferable. On the other hand, the upper limit of the content is preferably 20% by mass, more preferably 10% by mass, and still more preferably 5% by mass. By setting the content in the above range, the hardness of the lower layer film can be further improved.

[[D2] Cross-linking accelerator]
[D2] Crosslinking accelerators promote the formation of crosslinks by [D1] crosslinkers and the hydrolysis condensation by hydrolyzable groups remaining in [C2-1] polysiloxanes and [C2-2] complexes. . [D2] As the crosslinking accelerator, for example, a basic compound, a nitrogen-containing compound having an acid dissociable group, or the like can be used.

Examples of basic compounds include onium salt compounds that do not decompose by the action of heat, such as sulfonium salt compounds. Examples of the sulfonium salt compound include compounds represented by the following formula.

Examples of the nitrogen-containing compound having an acid dissociable group include Nt-butoxycarbonylpiperidine, Nt-butoxycarbonylimidazole, Nt-butoxycarbonylbenzimidazole, Nt-butoxycarbonyl-2-phenylbenzimidazole. N- (t-butoxycarbonyl) di-n-octylamine, N- (t-butoxycarbonyl) diethanolamine, N- (t-butoxycarbonyl) dicyclohexylamine, N- (t-butoxycarbonyl) diphenylamine, Nt -Butoxycarbonyl-4-hydroxypiperidine, Nt-amyloxycarbonyl-4-hydroxypiperidine and the like.

[D2] As the crosslinking accelerator, a sulfonium salt compound and a nitrogen-containing compound having an acid dissociable group are preferable, and triphenylsulfonium acetate and Nt-butoxycarbonyl-4-hydroxypiperidine are more preferable.

When the lower layer film-forming composition contains [D2] crosslinking accelerator, the lower limit of the content of [D2] crosslinking accelerator in the lower layer film-forming composition in terms of solid content is 0.1% by mass. Preferably, 0.5 mass% is more preferable, and 1.5 mass% is further more preferable. On the other hand, the upper limit of the content is preferably 20% by mass, more preferably 10% by mass, and still more preferably 5% by mass. By setting the content in the above range, the hardness of the lower layer film can be further improved.

The surfactant improves the uniformity of the coating surface of the lower layer film to be formed and suppresses the occurrence of coating spots. As specific examples of the surfactant, for example, those described in paragraph [0216] of JP-A-2016-206676 can be used.

The adhesion assistant improves the adhesion between the lower layer film and the underlying substrate. As the adhesion assistant, for example, a known adhesion assistant can be used.

([E] solvent)
[E] As a solvent, [A] a thermal acid generating component and / or [B] an acid group-containing component, and [C] an optional component such as an organic polymer contained as necessary are dissolved or dispersed. Although it will not specifically limit if it can be performed, For example, an alcohol solvent, a ketone solvent, an amide solvent, an ether solvent, an ester solvent etc. are mentioned.

Examples of the alcohol solvent include methanol, ethanol, n-propanol, iso-propanol, n-butanol, iso-butanol, sec-butanol, t-butanol, n-pentanol, iso-pentanol, sec-pentanol. And monoalcohol solvents such as t-pentanol, 2-methylpentanol and 4-methyl-2-pentanol.

Examples of the ether solvent include polyhydric alcohol partial ether solvents such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol dimethyl ether, propylene glycol monoethyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate. And polyhydric alcohol partial ether acetate solvents such as propylene glycol monomethyl ether acetate (PGMEA) and propylene glycol monoethyl ether acetate.

[E] As the solvent, in addition to the solvents described above, the solvents described in paragraphs [0185] to [0189] of JP-A-2016-206676 can also be used.

[E] As the solvent, ether solvents, ketone solvents and ester solvents are preferable, and ether solvents are more preferable. The ether solvent is preferably a polyhydric alcohol partial ether solvent and a polyhydric alcohol partial ether acetate solvent, more preferably a polyhydric alcohol partial ether solvent and propylene glycol monoalkyl ether acetate, propylene glycol monoethyl ether and PGMEA. Is more preferable.

[E] As the solvent, ether solvents, ketone solvents and ester solvents are preferable, and ether solvents are more preferable. The ether solvent is preferably a polyhydric alcohol partial ether solvent, a polyhydric alcohol partial ether acetate solvent, or a dialiphatic ether solvent, more preferably a polyhydric alcohol partial ether solvent or a polyhydric alcohol partial ether acetate solvent. Preferably, a polyhydric alcohol partial ether solvent and propylene glycol monoalkyl ether acetate are more preferable, and propylene glycol monoethyl ether and PGMEA are particularly preferable. As the ketone solvent, a cyclic ketone solvent is preferable, and cyclohexanone and cyclopentanone are more preferable. As the ester solvent, a carboxylic acid ester solvent and a lactone solvent are preferable, a carboxylic acid ester solvent is more preferable, and ethyl lactate is more preferable.

[E] The solvent contains a polyhydric alcohol partial ether acetate solvent, particularly propylene glycol monoalkyl ether acetate, particularly PGMEA, from the viewpoint of improving the coating property of the composition for forming the lower layer film to a substrate such as a silicon wafer. It is preferable to do. Since each component such as the [C] organic polymer contained in the composition for forming the lower layer film tends to dissolve in PGMEA and the like, the [E] solvent contains a polyhydric alcohol partial ether acetate solvent. The coating property of the composition for forming the lower layer film can be improved, and as a result, the embedding property of the lower layer film can be improved. [E] The lower limit of the content of the polyhydric alcohol partial ether acetate solvent in the solvent is preferably 20% by mass, more preferably 60% by mass, and even more preferably 90% by mass. Moreover, as said content rate, 100 mass% is the most preferable.

(Method for preparing composition for forming underlayer film)
The composition for forming an underlayer film is a mixture of [A] a thermal acid generating component and / or [B] acid group-containing component and an optional component such as [C1] organic polymer used as necessary. Preferably, the obtained mixture can be prepared by filtering through a membrane filter of about 0.45 μm. As a minimum of solid content concentration in a constituent for lower layer film formation, 0.1 mass% is preferred, 1 mass% is more preferred, and 2 mass% is still more preferred. On the other hand, the upper limit of the solid content concentration is preferably 50% by mass, more preferably 30% by mass, and even more preferably 15% by mass.

[Radiosensitive composition for resist film formation]
The radiation-sensitive composition for forming a resist film contains 50% by mass or more of [P] metal-containing compound in terms of solid content. The radiation-sensitive composition for forming a resist film preferably further contains a [Q] solvent, and may further contain other components. Since the radiation sensitive composition for forming a resist film contains 50% by mass or more of [P] metal-containing compound in terms of solid content, a resist film having excellent etching resistance can be formed.

([P] metal-containing compound)
[P] The metal-containing compound is a compound containing a metal atom. [P] A metal containing compound can be used individually by 1 type or in combination of 2 or more types. Moreover, the metal atom which comprises a [P] metal containing compound can be used individually by 1 type or in combination of 2 or more types. Here, the “metal atom” is a concept including a semimetal, that is, boron, silicon, germanium, arsenic, antimony and tellurium.

[P] The metal atom constituting the metal-containing compound is not particularly limited, and examples thereof include group 3 to group 16 metal atoms. Specific examples of the metal atom include a group 4 metal atom such as titanium, zirconium and hafnium, a group 5 metal atom such as tantalum, a group 6 metal atom such as chromium and tungsten, iron, ruthenium and the like. Group 8 metal atoms such as cobalt, Group 9 metal atoms such as cobalt, Group 10 metal atoms such as nickel, Group 11 metal atoms such as copper, Group 12 metals such as zinc, cadmium and mercury Group 13 metal atoms such as atoms, boron, aluminum, gallium, indium and thallium, Group 14 metal atoms such as germanium, tin and lead, Group 15 metal atoms such as antimony and bismuth, Group such as tellurium Examples include group 16 metal atoms.

[P] The metal atom constituting the metal-containing compound includes the first metal atom belonging to Group 4, Group 12, or Group 14 in the periodic table and belonging to the fourth period, the fifth period, or the sixth period. Good. That is, the metal atom may include at least one of titanium, zirconium, hafnium, zinc, cadmium, mercury, germanium, tin, and lead. As described above, since the [P] metal-containing compound contains the first metal atom, the secondary electrons are emitted from the exposed portion of the resist film, and the [P] metal-containing compound is dissolved in the developer by the secondary electrons. Sex change is promoted more. As a result, the sensitivity of the pattern forming method can be further improved, and pattern collapse can be more reliably suppressed. As the first metal atom, tin is preferable.

[P] It is preferable that the metal-containing compound further has an atom other than the metal atom. As said other atom, a carbon atom, a hydrogen atom, an oxygen atom, a nitrogen atom, a phosphorus atom, a sulfur atom, a halogen atom etc. are mentioned, for example, Among these, a carbon atom, a hydrogen atom, and an oxygen atom are preferable. [P] Other atoms in the metal-containing compound can be used alone or in combination of two or more.

The lower limit of the content of the [P] metal-containing compound in terms of solid content in the radiation-sensitive composition for resist film formation is preferably 70% by mass, more preferably 90% by mass, and still more preferably 95% by mass. Further, the content may be 100% by mass. Here, solid content in the radiation sensitive composition for resist film formation means components other than the [Q] solvent mentioned later.

(Method for synthesizing [P] metal-containing compound)
[P] The metal-containing compound includes, for example, a hydrolytic condensate reaction, a metal compound having a metal atom and a hydrolyzable group, a hydrolyzate of the metal compound, a hydrolyzed condensate of the metal compound, or a combination thereof. It can be obtained by a method of performing a ligand exchange reaction or the like. The said metal compound can be used individually by 1 type or in combination of 2 or more types.

[P] The metal-containing compound is preferably derived from a metal compound having a metal atom and a hydrolyzable group represented by the following formula (1) (hereinafter also referred to as “metal compound (1)”). By using such a metal compound (1), a stable [P] metal-containing compound can be obtained.

In the above formula (1), M is a metal atom. L is a ligand or a monovalent organic group having 1 to 20 carbon atoms. a is an integer of 0-6. When a is 2 or more, the plurality of L may be the same or different. Y is a monovalent hydrolyzable group. b is an integer of 2 to 6. A plurality of Y may be the same or different. L is a ligand or organic group not corresponding to Y.

As the metal atom represented by M, the first metal atom is preferable, and tin is more preferable.

The hydrolyzable group represented by Y can be appropriately changed according to the metal atom represented by M. For example, a substituted or unsubstituted ethynyl group, a halogen atom, an alkoxy group, an acyloxy group, a substituted or non-substituted group. Examples include substituted amino groups.

As the substituent in the substituted or unsubstituted ethynyl group represented by Y and the substituted or unsubstituted amino group, a monovalent hydrocarbon group having 1 to 20 carbon atoms is preferable, and a chain hydrocarbon group is more preferable. An alkyl group is more preferable.

Examples of the halogen atom represented by Y include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Of these, a chlorine atom is preferred.

Examples of the alkoxy group represented by Y include a methoxy group, an ethoxy group, an n-propoxy group, an i-propoxy group, and an n-butoxy group. Of these, an ethoxy group, i-propoxy group, and n-butoxy group are preferable.

As the acyloxy group represented by Y, for example, formyl group, acetoxy group, ethylyloxy group, propionyloxy group, n-butyryloxy group, t-butyryloxy group, t-amylyloxy group, n-hexanecarbonyloxy group, n-octane Examples thereof include a carbonyloxy group. Of these, an acetoxy group is preferred.

Examples of the substituted or unsubstituted amino group represented by Y include an amino group, a methylamino group, a dimethylamino group, a diethylamino group, and a dipropylamino group. Among these, a dimethylamino group and a diethylamino group are preferable.

Hereinafter, preferred combinations of the metal atom represented by M and the hydrolyzable group represented by Y will be described. When the metal atom represented by M is tin, the hydrolyzable group represented by Y includes a substituted or unsubstituted ethynyl group, a halogen atom, an alkoxy group, an acyloxy group, and a substituted or unsubstituted amino group. Preferably, a halogen atom is more preferable. When the metal atom represented by M is germanium, the hydrolyzable group represented by Y is preferably a halogen atom, an alkoxy group, an acyloxy group, or a substituted or unsubstituted amino group. When the metal atom represented by M is hafnium, zirconium and titanium, the hydrolyzable group represented by Y is preferably a halogen atom, an alkoxy group or an acyloxy group.

Examples of the ligand represented by L include a monodentate ligand and a polydentate ligand.

Examples of the monodentate ligand include a hydroxo ligand, a nitro ligand, and ammonia.

Examples of the polydentate ligand include the polydentate ligands exemplified in the [C2-2] complex, diphosphine, and the like.

Examples of the diphosphine include 1,1-bis (diphenylphosphino) methane, 1,2-bis (diphenylphosphino) ethane, 1,3-bis (diphenylphosphino) propane, and 2,2′-bis (diphenyl). Phosphino) -1,1′-binaphthyl, 1,1′-bis (diphenylphosphino) ferrocene and the like.

Examples of the monovalent organic group represented by L include the same groups as those described as the monovalent organic group represented by R ^X1 in the above formula (I). The lower limit of the carbon number of the monovalent organic group represented by L is preferably 2, and more preferably 3. On the other hand, the upper limit of the carbon number is preferably 10, and more preferably 5. The monovalent organic group represented by L is preferably a substituted or unsubstituted hydrocarbon group, more preferably a substituted or unsubstituted chain hydrocarbon group, still more preferably a substituted or unsubstituted alkyl group, t A butyl group is particularly preferred.

A is preferably 1 or 2, and more preferably 1.

B is preferably an integer of 2 to 4. By making b into the said numerical value, the content rate of the metal atom in a [P] metal containing compound can be raised, and generation | occurrence | production of the secondary electron by a [P] metal containing compound can be accelerated | stimulated more effectively. As a result, the sensitivity of the pattern forming method can be further improved, and pattern collapse can be more reliably suppressed.

As the metal compound (1), a metal halide compound is preferable, and a compound represented by the following formula is more preferable.

As a method for performing a hydrolysis-condensation reaction on the metal compound (1), for example, in the presence of a base such as tetramethylammonium hydroxide used as necessary, the metal compound (1) in water or a solvent containing water. And the like. In this case, you may add the other compound which has a hydrolysable group as needed. The lower limit of the amount of water used for this hydrolysis-condensation reaction is preferably 0.2 times mole, more preferably 1 time mole, and even more preferably 3 times mole relative to the hydrolyzable group of the metal compound (1) and the like. preferable. By making the amount of water in the hydrolysis condensation reaction within the above range, the [P] metal-containing compound can be obtained easily and reliably.

[P] In the synthesis reaction of the metal-containing compound, in addition to the metal compound (1), it becomes a compound or a bridging ligand that can be a multidentate ligand represented by L in the compound of the above formula (1). You may add the compound etc. which are obtained. Examples of the compound that can be a bridging ligand include compounds having two or more coordinateable groups such as a hydroxy group, an isocyanate group, an amino group, an ester group, and an amide group.

[P] The lower limit of the temperature of the synthesis reaction of the metal-containing compound is preferably 0 ° C, and more preferably 10 ° C. As an upper limit of the said temperature, 150 degreeC is preferable, 100 degreeC is more preferable, and 50 degreeC is further more preferable.

[P] The lower limit of the synthesis reaction of the metal-containing compound is preferably 1 minute, more preferably 10 minutes, and even more preferably 1 hour. The upper limit of the time is preferably 100 hours, more preferably 50 hours, further preferably 24 hours, and particularly preferably 4 hours.

([Q] solvent)
[Q] The solvent is preferably an organic solvent. Specific examples of the organic solvent include those similar to those exemplified as the solvent [E] in the composition for forming a lower layer film.

[Q] The solvent is preferably an alcohol solvent, more preferably a monoalcohol solvent, and even more preferably 4-methyl-2-pentanol.

[Other optional ingredients]
In addition to the [P] metal-containing compound and the [Q] solvent, the radiation-sensitive composition for forming a resist film may contain other optional components such as a compound that can be a ligand and a surfactant.

[Compound that can be a ligand]
Examples of the compound that can be a ligand include compounds that can be a multidentate ligand or a bridging ligand. Specifically, the polydentate ligand exemplified in the method for synthesizing a [P] metal-containing compound. Or the thing similar to the compound which can become a bridge | crosslinking ligand etc. are mentioned.

[Surfactant]
A surfactant is a component that exhibits an effect of improving coatability, striation and the like. Examples of the surfactant include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene n-octylphenyl ether, polyoxyethylene n-nonylphenyl ether, polyethylene glycol dilaurate, polyethylene glycol diacrylate. In addition to nonionic surfactants such as stearate, the following trade names are KP341 (Shin-Etsu Chemical Co., Ltd.), Polyflow No. 75, no. 95 (above, Kyoeisha Chemical Co., Ltd.), F-Top EF301, EF303, EF352 (above, Tochem Products), MegaFuck F171, F173 (above, Dainippon Ink and Chemicals), Florard FC430, FC431 ( Sumitomo 3M), Asahi Guard AG710, Surflon S-382, SC-101, SC-102, SC-103, SC-104, SC-105, SC-105, SC-106 (above, Asahi Glass Co., Ltd.) ) And the like.

(Method for preparing radiation-sensitive composition for resist film formation)
The radiation-sensitive composition for forming a resist film is obtained by, for example, mixing [P] a metal-containing compound and other optional components such as a [Q] solvent as necessary, and preferably the obtained mixture. Can be prepared by filtering with a membrane filter having a pore size of about 0.2 μm. When the radiation-sensitive composition for forming a resist film contains a [Q] solvent, the lower limit of the solid content concentration of the radiation-sensitive composition for forming a resist film is preferably 0.1% by mass, and 0.5% by mass. Is more preferable, 1% by mass is more preferable, and 2% by mass is particularly preferable. On the other hand, the upper limit of the solid content concentration is preferably 50% by mass, more preferably 30% by mass, further preferably 15% by mass, and particularly preferably 4% by mass. Here, the “solid content” in the radiation-sensitive composition for forming a resist film refers to components other than the [Q] solvent.

Hereinafter, each step of the pattern forming method using the above-described composition for forming a lower layer film and the radiation-sensitive composition for forming a resist film will be described.

[Underlayer forming composition coating process]
In this step, the above-described composition for forming a lower layer film is applied to a substrate. Specifically, the composition for forming the lower layer film is applied to one surface side of the substrate so that the obtained lower layer film has a desired thickness, and then the composition for forming the lower layer film by pre-baking (PB) as necessary. The lower layer film is formed by volatilizing the [E] solvent of the product. The method for applying the composition for forming the lower layer film to the substrate is not particularly limited, and appropriate application means such as spin coating, cast coating, roll coating, etc. can be employed. Examples of the substrate include a silicon wafer, a silicon wafer coated with aluminum, a substrate resin substrate including an insulating film such as silicon oxide, silicon nitride, silicon oxynitride, and polysiloxane. Examples of the silicon oxide insulating film include a low dielectric constant insulating film formed of porous silica. Among these, a substrate provided with an insulating film of silicon nitride and a substrate provided with a low dielectric constant insulating film are preferable. In such a substrate, amine tends to be easily released from the insulating film at the time of pattern formation. However, according to the pattern formation method, the amine can be trapped by the lower layer film, so that poisoning can be effectively suppressed. .

The lower limit of the average thickness of the lower layer film formed in this step is preferably 1 nm, more preferably 10 nm, and further preferably 20 nm. On the other hand, the upper limit of the average thickness is preferably 20,000 nm, more preferably 1,000 nm, and even more preferably 100 nm.

The lower limit of the PB temperature in this step is preferably 150 ° C, more preferably 200 ° C, and even more preferably 250 ° C. On the other hand, the upper limit of the PB temperature is preferably 400 ° C., more preferably 350 ° C., and further preferably 300 ° C. or less. Further, the lower limit of the PB time is preferably 15 seconds, more preferably 30 seconds, and even more preferably 45 seconds. On the other hand, the upper limit of the PB time is preferably 1,200 seconds, more preferably 600 seconds, and even more preferably 300 seconds. By setting the PB temperature and the PB temperature in the above ranges, it is possible to reliably exhibit the characteristics necessary for the lower layer film.

In this step, an underlayer film forming composition containing at least one organic polymer component among [A2] thermal acid generating polymer, [B2] acid group-containing polymer and [C1] organic polymer is used, It is preferable to form an organic underlayer film. Thereby, the etching selectivity of the lower layer film and the resist film can be improved. In this case, as a minimum of the carbon content rate in an organic underlayer film, 50 mass% is preferred, 60 mass% is more preferred, and 80 mass% is still more preferred. On the other hand, the upper limit of the carbon content is preferably 99% by mass, and more preferably 95% by mass. The etching selectivity of a lower layer film and a resist film can be improved more by making the said carbon content rate into the said range. Here, the carbon content is a value measured by elemental analysis by a combustion method.

In this step, a plurality of lower layer films may be formed by repeating the coating and pre-baking of the lower layer film forming composition described above a plurality of times. In this case, the number of layers of the lower layer film to be formed can be, for example, 2 or more and 5 or less. In addition, the same underlayer film forming composition may be used for forming each underlayer film, or different underlayer film forming compositions may be used.

[Resistance film forming radiation sensitive composition coating process]
In this step, the above-mentioned radiation sensitive composition for forming a resist film is applied directly or indirectly on the lower layer film formed by the lower layer film forming composition coating step. Specifically, the resist film-forming radiation-sensitive composition is applied on the surface of the lower layer film opposite to the substrate so that the resulting resist film has a desired thickness, and then pre-baked (PB) as necessary. The resist film is formed by volatilizing the [Q] solvent or the like of the radiation-sensitive composition for forming a resist film. Although it does not specifically limit as a method to apply the radiation sensitive composition for resist film formation, For example, the method similar to the coating method illustrated in the composition application | coating process for lower layer film | membrane etc. is mentioned.

The lower limit of the average thickness of the resist film formed in this step is preferably 1 nm, more preferably 5 nm, still more preferably 10 nm, and particularly preferably 20 nm. On the other hand, the upper limit of the average thickness is preferably 1,000 nm, more preferably 200 nm, still more preferably 100 nm, and particularly preferably 70 nm.

As the lower limit of the PB temperature in this step, 50 ° C is preferable, and 70 ° C is more preferable. On the other hand, the upper limit of the PB temperature is preferably 140 ° C, and more preferably 100 ° C. The lower limit of the PB time is preferably 5 seconds, and more preferably 10 seconds. On the other hand, the upper limit of the PB time is preferably 600 seconds, and more preferably 300 seconds.

In this step, for example, a protective film can be provided on the formed resist film in order to prevent the influence of basic impurities and the like contained in the environmental atmosphere. Further, as described later, when immersion exposure is performed in the exposure step, an immersion protective film may be provided on the formed resist film in order to avoid direct contact between the immersion medium and the resist film.

[Exposure process]
In this step, the resist film formed in the radiation sensitive composition coating step for forming a resist film is exposed. Specifically, for example, the resist film is irradiated with radiation through a mask having a predetermined pattern. In this step, radiation irradiation through an immersion medium such as water, that is, immersion exposure may be employed as necessary. Examples of radiation to be exposed include visible rays, ultraviolet rays, far ultraviolet rays, EUV (wavelength 13.5 nm), electromagnetic waves such as X-rays and γ rays, and charged particle beams such as electron rays and α rays. Among these, EUV and an electron beam are preferable from the viewpoint of improving sensitivity.

[Development process]
In this step, the resist film exposed in the exposure step is developed. As a result, a predetermined positive or negative pattern is formed. Examples of the developer include an alkaline aqueous solution and an organic solvent-containing solution. From the viewpoint of developability and the like, an organic solvent-containing solution is preferable.

Examples of the alkaline aqueous solution include sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethylamine, ethyl Dimethylamine, triethanolamine, tetramethylammonium hydroxide (TMAH), pyrrole, piperidine, choline, 1,8-diazabicyclo- [5.4.0] -7-undecene, 1,5-diazabicyclo- [4.3 0.0] -5-nonene, and an alkaline aqueous solution in which at least one kind is dissolved.

The lower limit of the content of the alkaline compound in the alkaline aqueous solution is preferably 0.1% by mass, more preferably 0.5% by mass, and even more preferably 1% by mass. As an upper limit of the said content, 20 mass% is preferable, 10 mass% is more preferable, and 5 mass% is further more preferable.

As the alkaline aqueous solution, a TMAH aqueous solution is preferable, and a 2.38% by mass TMAH aqueous solution is more preferable.

Examples of the organic solvent in the organic solvent-containing liquid include the same organic solvents exemplified as the [Q] solvent in the radiation-sensitive composition for forming a resist film. Of these, ether solvents are preferred, polyhydric alcohol partial ether acetate solvents are more preferred, and propylene glycol monomethyl ether acetate is even more preferred.

The lower limit of the content of the organic solvent in the organic solvent-containing liquid is preferably 80% by mass, more preferably 90% by mass, further preferably 95% by mass, and particularly preferably 99% by mass. By making content of the said organic solvent into the said range, the contrast of the dissolution rate with respect to the developing solution in an exposure part and an unexposed part can be improved more. In addition, as components other than the organic solvent of the said organic solvent containing liquid, water, silicone oil, etc. are mentioned, for example.

An appropriate amount of a surfactant may be added to the developer as necessary. As the surfactant, for example, an ionic or nonionic fluorine-based surfactant, a silicone-based surfactant, or the like can be used.

As a developing method, for example, a method in which a substrate is immersed in a tank filled with a developer for a certain period of time (dip method), a method in which the developer is raised on the surface of the substrate by surface tension and is left stationary for a certain time (paddle method) ), A method of spraying the developer on the substrate surface (spray method), a method of continuously discharging the developer while scanning the developer discharge nozzle at a constant speed on the substrate rotating at a constant speed (dynamic dispensing method), etc. Is mentioned.

The substrate after the development is preferably rinsed with a rinse liquid such as water or alcohol and then dried. As the rinsing method, for example, a method of continuously discharging a rinsing liquid onto a substrate rotating at a constant speed (rotary coating method), a method of immersing the substrate in a tank filled with the rinsing liquid for a predetermined time (dip method) ), A method (spray method) of spraying a rinse liquid on the substrate surface, and the like.

Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited to these examples. The measuring method of various physical property values is shown below.

<Synthesis of metal-containing compounds>
(Synthesis Example 1)
10.0 mmol of tert-butyltrichlorotin (compound represented by the following formula (p-1)) was put into 100 g of 0.3M tetramethylammonium hydroxide aqueous solution, and vigorously stirred at room temperature for 90 minutes. The deposited precipitate was filtered and washed twice with 50 g of water to obtain a metal-containing compound (P-1) represented by the following formula (P-1).

<Preparation of radiation-sensitive composition for resist film formation>
(Synthesis Example 2)
3.0 parts by mass of the metal-containing compound (P-1) and 97.0 parts by mass of 4-methyl-2-pentanol as a [Q] solvent were mixed, and the resulting mixture was mixed with a membrane having a pore size of 0.2 μm. By filtering with a filter, a radiation-sensitive composition (J-1) for forming a resist film was prepared.

<Preparation of composition for forming lower layer film>
[A] thermal acid generating component, [B] acid group-containing component, [C] organic polymer, [D] additive and [E] solvent used for the preparation of the underlayer film forming composition are shown below.

([A] Thermal acid generating component)
[A1] Compounds (A-1) to (A-3) which are thermal acid generators and [A2] resin (A-4) which is a thermal acid generating polymer are shown below.
A-1: Bis (4-t-butylphenyl) iodonium nonafluoro-n-butanesulfonate (compound represented by the following formula (a-1), pKa of a component generated by the action of heat: -3.4)
A-2: Bis (4-t-butylphenyl) iodonium trifluoromethanesulfonate (a compound represented by the following formula (a-2), pKa of a component generated by the action of heat: -3.4)
A-3: Bis (4-t-butylphenyl) iodonium-10-camphorsulfonate (compound represented by the following formula (a-3), pKa of the component generated by the action of heat: 1.1)
A-4: Resin represented by the following formula (a-4) (Mw: 3,000)

([B] acid group-containing component)
[B2] Resin (B-1) which is an acid group-containing polymer is shown below.
B-1: Resin represented by the following formula (b-1) (Mw: 3,000)

([C1] organic polymer and [C2] inorganic polymer)
[C1] Resins (C-1) to (C-6) as organic polymers and [C2] Resins (C-7) to (C-12) as inorganic polymers are shown below.
C-1: Resin represented by the following formula (c-1) (Mw: 2,000)
C-2: Resin represented by the following formula (c-2) (Mw: 1,100)
C-3: Resin represented by the following formula (c-3) (Mw: 2,000)
C-4: Resin represented by the following formula (c-4) (Mw: 1,800)
C-5: Resin represented by the following formula (c-5) (Mw: 2,800)
C-6: Resin represented by the following formula (c-6) (Mw: 2,000)
C-7: Resin represented by the following formula (c-7) (Mw: 1,500)
C-8: Resin represented by the following formula (c-8) (Mw: 2,000)
C-9: Resin represented by the following formula (c-9) (Mw: 2,000)
C-10: Resin represented by the following formula (c-10) (Mw: 3,000)
C-11: Resin represented by the following formula (c-11) (Mw: 2,500)
C-12: Resin represented by the following formula (c-12) (Mw: 3,000)

[A2] Resin (A-4) which is a thermal acid generating polymer, [B2] Resin (B-1) which is an acid group-containing polymer, and [C1] Resin (C—) which is an organic polymer. 1) to (C-6) and [C2] resins (C-7) to (C-12), which are inorganic polymers, were synthesized by a conventionally known method.

([D] additive)
[D1] Compounds (D-1) to (D-3) which are crosslinking agents and [D2] compounds (D-4) to (D-5) which are crosslinking accelerators are shown below.
D-1: 1,3,4,6-tetrakis (methoxymethyl) glycoluril (compound represented by the following formula (d-1))
D-2: 5,5 ′-(1-methylethylidene) bis (2-hydroxy-1,3-benzenedimethanol) (compound represented by the following formula (d-2))
D-3: 2,4,6-tris [bis (methoxymethyl) amino] -1,3,5-triazine (compound represented by the following formula (d-3))
D-4: Nt-butoxycarbonyl-4-hydroxypiperidine (compound represented by the following formula (d-4))
D-5: Triphenylsulfonium acetate (compound represented by the following formula (d-5))

([E] solvent)
[E] Solvents (E-1) to (E-2) as solvents are shown below.
E-1: Propylene glycol monomethyl ether acetate E-2: Propylene glycol monoethyl ether

(Synthesis Example 3)
Dissolve 0.3 part by mass of the thermal acid generator (A-1) and 2.7 parts by mass of the resin (C-1) which is an [C] organic polymer in 97.0 parts by mass of the solvent (E-1). did. This solution was filtered through a membrane filter having a pore size of 0.45 μm to prepare a composition for forming an underlayer film (U-1).

(Synthesis Examples 4 to 27)
Except for using each component of the kind and content shown in Table 1, the same operation as in Synthesis Example 3 was carried out, and underlayer film forming compositions (U-2) to (U-22) and (u-1) to (U-3) was prepared. In Table 1, “-” indicates that the corresponding component was not used.

<Pattern formation>
The patterns of Examples 1 to 22 and Comparative Examples 1 to 3 were formed by the method described below, and the poisoning suppression was evaluated by measuring the pattern tailing and wide area damage suppression of the obtained patterns. The evaluation results are shown in Table 2.

Example 1
[Formation of low dielectric constant insulating film]
A low dielectric constant insulating film was formed on a silicon substrate in accordance with paragraphs [0112] to [0113] of JP 2010-106100 in “Clean Track ACT-8” of Tokyo Electron.

[Formation of lower layer film]
The obtained low dielectric constant insulating film substrate was immersed in a triethylamine solution and heated at 80 ° C. for 10 minutes to adsorb the amine component to the low dielectric constant insulating film. Thereafter, the lower film dielectric composition (U-1) was spin coated on the above-mentioned low dielectric constant insulating substrate in “Clean Track ACT-8” of Tokyo Electron Co., Ltd., and then subjected to PB at 270 ° C. for 180 seconds. And a lower layer film having an average thickness of 50 nm was formed.

[Formation of resist film]
After spin coating the radiation sensitive composition (J-1) for forming a resist film on the low dielectric constant insulating substrate on which the lower layer film was formed in “Clean Track ACT-8” of Tokyo Electron, 80 ° C. PB was performed under conditions for 60 seconds to form a resist film having an average thickness of 50 nm.

[Pattern formation]
The resist film was irradiated with an electron beam using a simple electron beam lithography system (“HL800D”, Hitachi, Ltd., output: 50 KeV, current density: 5.0 amperes / cm ² ). The electron beam was irradiated so that a line-and-space pattern (1L1S) in which the line portion and the space portion formed between adjacent line portions were 1: 1 was formed. After the electron beam irradiation, the resist film was developed by the paddle method at 23 ° C. for 1 minute in propylene glycol monomethyl ether acetate in the clean track ACT-8, and then dried to form a pattern.

[Pattern tailing suppression]
In a line-and-space pattern (1L1S) composed of a line portion having a line width of 150 nm and a space portion having an interval of 150 nm formed by adjacent line portions, it is determined whether or not the line pattern causes tailing. Observation was carried out using a microscope (“S-4800” manufactured by Hitachi High-Technologies Corporation). The pattern skirting suppression property was determined to be “A” (good) when the pattern shape was recognized as a rectangle and the skirt was not drawn, and “B” (bad) when the skirt was drawn.

[Wide area damage suppression]
For the pattern formed in the above-described evaluation of pattern tailing suppression, use a scanning electron microscope ("S-9380" manufactured by Hitachi High-Technologies Corporation) to observe a range of 10 µm × 10 µm and peel it off with propylene glycol monomethyl ether acetate The presence or absence of the resist film remaining in the space portion was confirmed. For the wide area damage suppression, the case where the resist film did not remain was judged as “A” (good), and the case where it was found was judged as “B” (bad).

(Examples 2 to 22 and Comparative Examples 1 to 3)
Except for using the underlayer film forming composition shown in Table 2, the same operation as in Example 1 was carried out, and the formation of patterns in Examples 2 to 22 and Comparative Examples 1 to 3 were evaluated.

(Example 23)
In the formation of the lower layer film, a first lower layer film having an average thickness of 50 nm is formed from the lower layer film forming composition (U-7), and then the lower layer film forming composition (U The pattern of Example 23 was formed and evaluated in the same manner as in Example 1 except that the second lower layer film having an average thickness of 50 nm was formed in -1). The first lower layer film and the second lower layer film were both formed by spin coating and performing PB under the conditions of 270 ° C. and 180 seconds.

(Example 24)
Except that the first underlayer film was formed of the underlayer film forming composition (U-11), the same operation as in Example 23 was performed, and the pattern of Example 24 was formed and evaluated.

As shown in Table 2, it can be evaluated that the pattern forming method of the example is excellent in both the pattern skirt suppression and the wide area damage suppression and excellent in the poisoning suppression. On the other hand, the pattern forming method of the comparative example was poor in both the pattern skirt suppression and the wide area damage suppression.

According to the pattern forming method of the present invention, poisoning such as pattern tailing and wide area damage can be suppressed. Accordingly, these can be suitably used for semiconductor device processing processes and the like that are expected to be further miniaturized in the future.

Claims (10)

1. Applying a composition for forming an underlayer film to a substrate;
   Coating the radiation-sensitive composition for forming a resist film directly or indirectly on the lower layer film formed by the above-mentioned composition for forming a lower layer film; and
   Exposing the resist film formed by the radiation sensitive composition coating process for forming the resist film;
   A step of developing the exposed resist film,
   The composition for forming the lower layer film is a sulfo group, a carboxy group, a phosphono group, a phosphoric acid group, a sulfuric acid group, a sulfonamide group, a sulfonylimide group, -CR ^F1 R ^F2 OH (R ^F1 is a fluorine atom or a fluorinated alkyl group) R ^F2 is a hydrogen atom, a fluorine atom or a fluorinated alkyl group) or a component having an acid group which is a combination thereof, and a component other than the first component And at least one of the above-mentioned second component having an acid group,
   The pattern formation method in which the said radiation sensitive composition for resist film formation contains a metal containing compound 50 mass% or more in conversion of solid content.
2. The underlayer film forming composition is
   The pKa of the component containing the first component and having the acid group generated by the action of heat from the first component is 3 or less, or containing the second component, and the pKa of the second component is The pattern forming method according to claim 1, wherein the pattern forming method is 3 or less.
3. The composition for forming the lower layer film includes a first organic polymer as the first component, a second organic polymer as the second component, and a third organic polymer other than the first component and the second component. Contains at least one organic polymer component,
   The pattern forming method according to claim 1, wherein an organic underlayer film is formed in the underlayer film forming composition coating step.
4. The pattern formation method according to claim 3, wherein the carbon content in the organic underlayer film is 50% by mass or more.
5. The pattern forming method according to claim 3 or 4, wherein the organic polymer component has a weight average molecular weight of 30,000 or less.
6. The pattern forming method according to claim 3, 4 or 5, wherein the organic polymer component has an aromatic ring.
7. The pattern formation method according to any one of claims 1 to 6, wherein the metal-containing compound is derived from a compound represented by the following formula (1).
   

   

   (In the formula (1), M is a metal atom. L is a ligand or a monovalent organic group having 1 to 20 carbon atoms. A is an integer of 0 to 6. a is 2) In the above case, a plurality of L may be the same or different, Y is a monovalent hydrolyzable group, b is an integer of 2 to 6. A plurality of Y may be the same or different. (Note that L is a ligand that does not correspond to Y.)
8. The metal atom constituting the metal-containing compound includes a first metal atom belonging to Group 4, Group 12, or Group 14 in the periodic table and belonging to the fourth period, the fifth period, or the sixth period. The pattern formation method of any one of Claim 1-7.
9. The pattern formation method according to any one of claims 1 to 8, wherein the composition for forming an underlayer film further contains a crosslinking agent.
10. The pattern forming method according to claim 1, wherein the composition for forming a lower layer film further contains a crosslinking accelerator.