Method for producing siliceous film

Abstract

A method for producing a siliceous film on a substrate having grooves is provided. A method for producing a siliceous membrane, comprising the steps of: (a) applying a siliceous film composition to a substrate having a groove to form a composition layer; (b) exposing the composition layer to an atmosphere containing a basic compound gas and water vapor; and (c) heating the substrate to cure the composition layer wherein the basic compound is ammonia, a quaternary ammonium compound, or any combination thereof.

Description

[Technical Field]

[0001] The present invention relates to a method for producing a siliceous film. [Background technology]

[0002] In the manufacture of electronic devices, particularly semiconductor devices, interlayer insulating films are formed between transistor elements and bit lines, between bit lines and capacitors, between capacitors and metal wiring, between multiple metal wirings, etc. Furthermore, insulating materials are sometimes filled into isolation trenches formed on the surface of a substrate, etc. Silica films are often used as such insulating films.

[0003] Siliceous films can be formed by chemical vapor deposition (CVD), sol-gel methods, applying a liquid composition containing a silicon-containing polymer, and baking the liquid composition. Among these, the method of forming a siliceous film using a liquid composition is often used because it is relatively simple. A siliceous film can be formed by applying a composition containing a silicon-containing polymer such as polysilazane to the surface of a substrate or the like, and converting it to silica by heating or the like. In order to form a dense siliceous film and improve the efficiency of the process, it has been proposed to include a step of contacting the silica conversion with vapor containing an amine compound (for example, Patent Documents 1 and 2).

[0004] When a coating film is formed by filling a groove with a liquid composition, if the groove has a complex structure or is deep, the film stress becomes non-uniform during heating for curing, making it more likely to crack and making it difficult to form a dense cured film. With the increasing integration density of semiconductor integrated circuits, a method for uniformly filling deeper grooves with a high aspect ratio is required. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 9-183663 [Patent Document 2] Japanese Patent Application Laid-Open No. 2001-89126 Summary of the Invention [Problem to be solved by the invention]

[0006] The present inventors have recognized that there are one or more problems that still need improvement in the method for producing a siliceous film on a substrate having grooves, such as the following: Deeper grooves are more likely to crack; shrinkage of the film thickness is not sufficiently suppressed when heated for curing; low molecular weight components of the polymer are scattered when heated for curing; it is difficult to form a thick siliceous film; the process for forming the siliceous film is inefficient; the dry etching rate of the siliceous film formed in the groove is not constant in the depth direction; and there is a large difference in the wet etching rate of the siliceous film formed in the groove between the top and bottom of the groove. [Means for solving the problem]

[0007] The method for producing a siliceous film according to the present invention comprises the following steps: (a) applying a siliceous film composition to a substrate having a groove to form a composition layer; (b) exposing the composition layer to an atmosphere containing a basic compound gas and water vapor; and (c) heating the substrate to cure the composition layer comprising The basic compound is ammonia, a quaternary ammonium compound, or any combination thereof.

[0008] A method for producing an element of an electronic device according to the present invention comprises the above-described method. [Effects of the Invention]

[0009] According to the present invention, one or more of the following effects can be expected. The occurrence of cracks is suppressed even when the groove is deep; shrinkage of the film thickness is sufficiently suppressed when heated for curing; scattering of low molecular weight components of the polymer can be suppressed when heated for curing; a sufficiently thick siliceous film can be formed; a siliceous film can be formed efficiently; the dry etching rate of the siliceous film formed in the groove is constant in the depth direction; and the difference in wet etching rate of the siliceous film formed in the groove can be reduced between the top and bottom of the groove. [Brief explanation of the drawings]

[0010] [Figure 1] Electron micrograph of the grooved area without cracks. [Figure 2] Electron micrograph showing cracks in the grooved area. DETAILED DESCRIPTION OF THE INVENTION

[0011] [Definition] In this specification, unless otherwise specified, the definitions and examples set forth in this paragraph shall be followed. The singular includes the plural, and "one" and "the" mean "at least one." An element of a concept can be expressed by a plurality of species, and when an amount thereof (e.g., mass % or mole %) is stated, the amount refers to the sum of the plurality of species. "And / or" includes all combinations of elements as well as any single element. When a numerical range is indicated using "~" or "-", it includes both endpoints and the units are the same. For example, 5 to 25 mol % means 5 mol % or more and 25 mol % or less. Alkyl refers to a group obtained by removing any one hydrogen from a linear, branched, or cyclic saturated hydrocarbon, and includes linear alkyl, branched alkyl, and cyclic alkyl, and optionally contains a linear or branched alkyl as a side chain in a cyclic structure. Aryl refers to a group obtained by removing any one hydrogen from an aromatic hydrocarbon. "C x-y "," "C x ~C y" and "C x " refers to the number of carbons in a molecule or substituent. For example, C 1-6 Alkyl refers to alkyl chains having from 1 to 6 carbons (methyl, ethyl, propyl, butyl, pentyl, hexyl, etc.). When a polymer has multiple types of repeating units, these repeating units are copolymerized. This copolymerization may be alternating copolymerization, random copolymerization, block copolymerization, graft copolymerization, or a mixture of these. When polymers or resins are represented by structural formulas, the n or m in parentheses indicates the repeating number. The temperature unit is Celsius. For example, 20 degrees means 20 degrees Celsius. The additive refers to the compound itself that has that function (for example, in the case of a base generator, it refers to the compound itself that generates a base). The compound may be dissolved or dispersed in a solvent and added to the composition. In one embodiment of the present invention, such a solvent is preferably contained in the composition of the present invention as a solvent or other component.

[0012] Hereinafter, embodiments of the present invention will be described in detail.

[0013] <Method of manufacturing siliceous film> The method for producing a siliceous film according to the present invention comprises the following steps. (a) applying a siliceous film composition to a substrate having a groove to form a composition layer; (b) exposing the composition layer to an atmosphere containing a basic compound gas and water vapor; and (c) heating the substrate to cure the composition layer.

[0014] Process (a) Step (a) is a step of applying a siliceous film composition to a substrate having grooves to form a composition layer. In the present invention, the substrate may be a single layer or a laminate. The shape of the groove is not particularly limited, but in the present invention, a substrate having grooves or holes with a sufficiently high aspect ratio is preferred, as this has the advantage of being able to easily penetrate into narrow grooves and form a uniform cured film even inside the grooves. The aspect ratio is preferably 3 to 50, more preferably 5 to 30. The shape of the groove is not particularly limited, and the cross section may be any shape, such as a rectangular, forward tapered, reverse tapered, or curved shape. Furthermore, both ends of the groove may be open or closed. Substrates having grooves include, for example, substrates for electronic devices equipped with transistor elements, bit lines, capacitors, etc. The production of such electronic devices may include a through-hole formation process in which holes are formed vertically through the material filling the fine grooves, following a process such as forming an insulating film called PMD between a transistor element and a bit line, between a transistor element and a capacitor, between a bit line and a capacitor, or between a capacitor and a metal wiring, or an insulating film called IMD between multiple metal wirings, or filling an isolation groove.

[0015] The siliceous film composition is applied to a substrate, and in the present invention, the siliceous film composition may be applied directly to the substrate or may be applied to the substrate via one or more intermediate layers. There are no particular limitations on the method of applying the solution to the substrate, and examples thereof include ordinary application methods such as spin coating, dipping, spraying, transferring, and slit coating. A preferred siliceous film composition will be described later. A composition layer is formed by applying the siliceous film composition, and at this time, a drying step such as spin drying, reduced pressure, or pre-baking can be carried out as necessary. In a preferred embodiment, the method further includes, between step (a) and step (b), a step (pre-baking step) of heating the substrate on which the composition layer has been formed at 50° C. or higher, more preferably at 60 to 120° C. The pre-baking step is preferably carried out in a nitrogen atmosphere.

[0016] The siliceous film composition is preferably applied in an amount sufficient to sufficiently fill the grooves of the substrate. When the siliceous film composition is applied in an amount sufficient to sufficiently fill the grooves of the substrate, the grooves are filled with the siliceous film composition, and a composition layer is formed even in areas of the substrate surface that do not have grooves, a sufficiently thick composition layer is formed in the areas without grooves. For planarization, the method may further include a step of removing excess portions of the coating film. This removing step is preferably performed before the drying step, and more preferably, this removing step is performed after the formation of the composition layer and before pre-baking.

[0017] Process (b) Step (b) is a step of exposing the composition layer formed in step (a) to an atmosphere containing a basic compound gas and water vapor (hereinafter, sometimes referred to as a basic atmosphere). The basic compound is ammonia, a quaternary ammonium compound, or any combination thereof, preferably selected from the group consisting of ammonia, tetramethylammonium hydroxide, tetraethylammonium hydroxide (TEAH), tetrapropylammonium hydroxide, and tetrabutylammonium hydroxide, more preferably ammonia. Step (b) is preferably carried out under atmospheric pressure (101.3 kPa). The partial pressure of water vapor in the basic atmosphere is preferably 20 to 90 kPa, more preferably 25 to 90 kPa, and even more preferably 25 to 85 kPa, when the total pressure is 101.3 kPa. Step (b) is preferably carried out at a temperature of 20 to 200°C, more preferably 50 to 200°C, and even more preferably 50 to 150°C. The partial pressure of the basic compound gas in the basic atmosphere is preferably 2 to 50 kPa, more preferably 2 to 30 kPa, and even more preferably 10 to 25 kPa, when the total pressure is 101.3 kPa. The basic atmosphere may contain components other than the basic compound and water vapor (hereinafter, sometimes referred to as diluent gas), specific examples of which include air, oxygen, nitrogen, nitrous oxide, ozone, helium, argon, etc. The content of the diluent gas in the basic atmosphere is preferably 50 kPa or less, more preferably 40 kPa or less. The basic atmosphere is generated by a method such as introducing the above-mentioned basic compound gas into the treatment vessel followed by introducing water vapor, introducing water vapor into the treatment vessel followed by introducing the above-mentioned basic compound gas, or introducing an aqueous solution of the above-mentioned basic compound into the treatment vessel and heating it.

[0018] One of the features of the present invention is that the composition layer is exposed to an atmosphere containing a specific basic compound gas and water vapor before the curing step (c) of the composition layer. Without being bound by theory, exposing the composition layer to an atmosphere containing a basic compound gas and water vapor promotes conversion to a siliceous film with a small shrinkage rate, thereby suppressing dimensional changes near the groove opening. This prevents localized stress concentration near the opening, thereby suppressing the occurrence of cracks. The low-stress film near the opening prevents the generation of strong tensile stress at the bottom of the groove in the subsequent curing step (c), achieving a consistent dry etching rate from the groove opening to the bottom. Furthermore, because hydrates of basic compounds are the active species in the reaction that converts to a siliceous film with a small shrinkage rate, ammonia and quaternary ammonium compounds are effective, while triethylamine, which does not form hydrates, is ineffective.

[0019] Process (c) In step (c), the substrate is heated to harden the composition layer, thereby obtaining a siliceous film. The heating temperature in this step is not particularly limited as long as it is a temperature that hardens the composition layer. To promote the hardening reaction and obtain a sufficiently hardened film, the hardening temperature is preferably 200 to 1,000°C, more preferably 300 to 1,000°C. The heating time is not particularly limited, but is preferably 1 minute to 10 hours, more preferably 1 to 180 minutes. The atmosphere during hardening varies depending on the composition used, but is preferably a water vapor atmosphere or a nitrogen atmosphere. The curing process can be divided into two or more stages, for example, by first heating at a low temperature (for example, in the range of 200 to 400°C) in an atmosphere containing water vapor, and then heating (annealing) at a higher temperature (for example, 400 to 1,000°C) in an atmosphere not containing water vapor, preferably a nitrogen atmosphere. The water vapor-containing atmosphere in step (c) refers to an atmosphere in which the water vapor partial pressure is in the range of 0.5 to 101 kPa when the total pressure is 101.3 kPa, preferably 1 to 90 kPa, more preferably 1.5 to 80 kPa. Any gas can be used as the component other than water vapor in the water vapor-containing atmosphere, and specific examples include air, oxygen, nitrogen, nitrous oxide, ozone, helium, and argon, and preferably does not contain a basic compound gas. In this specification, the term "siliceous film" refers to a film having a ratio of the number of oxygen atoms to the number of silicon atoms (O / Si) of 1.20 to 2.50, preferably 1.40 to 2.50, and more preferably 1.60 to 2.45. The siliceous film may contain other atoms such as hydrogen, nitrogen, and carbon.

[0020] A method for manufacturing an electronic device according to the present invention comprises the method described above. The electronic device is preferably a semiconductor device.

[0021] [Siliceous film composition] The siliceous film composition (hereinafter sometimes referred to as the composition) used in the present invention is not particularly limited as long as it contains components that can form a siliceous film.

[0022] The component capable of forming a siliceous film may be a polymer, a polymerizable monomer component, or a mixture thereof. The composition according to the present invention preferably contains a silicon-containing polymer. In a preferred embodiment of the present invention, the composition used in the present invention comprises a silicon-containing polymer selected from the group consisting of polysilazanes, polycarbosilazanes, and polysiloxazanes. The mass average molecular weight of the silicon-containing polymer is preferably 1,000 to 30,000, more preferably 1,200 to 28,000, and even more preferably 1,500 to 25,000. In the present invention, the mass average molecular weight refers to a weight average molecular weight converted into polystyrene, and can be measured by gel permeation chromatography using polystyrene as the standard. The same applies to other polymers. The content of the silicon-containing polymer is preferably 10 to 100% by mass, more preferably 15 to 85% by mass, based on the total mass of the composition.

[0023] (Polysilazane) The polysilazanes used in the present invention are not particularly limited in structure and may be selected from any suitable ones depending on the purpose. Polysilazanes have Si-N bonds as their main skeletons, and may be either inorganic or organic compounds, and may be linear, branched, or partially cyclic.

[0024] Preferably, the polysilazane contains 20 or more, preferably 20 to 350, repeating units selected from the group consisting of the following formulae (1-i) to (1-vi). In this case, it is preferable that each repeating unit is directly bonded to the other repeating units without being connected via any repeating units other than (1-i) to (1-vi). [ka] (In the formula, R 1a ~R 1i are each independently hydrogen or C 1-4 alkyl)

[0025] More preferably, the polysilazane used in the present invention is perhydropolysilazane (hereinafter referred to as PHPS). PHPS is a silicon-containing polymer containing Si-N bonds as repeating units and consisting only of Si, N, and H. In this PHPS, all elements bonded to Si and N, except for the Si-N bonds, are H, and other elements such as carbon and oxygen are substantially absent. The simplest structure of perhydropolysilazane is a chain structure having the following repeating unit: [ka]

[0026] The structure of PHPS is not limited as long as it contains Si-N bonds as repeating units and is a silicon-containing polymer consisting only of Si, N, and H, and can take various structures in addition to those exemplified above. PHPS preferably has a cyclic structure or a crosslinked structure, particularly a crosslinked structure. The terminal group of perhydropolysilazane is preferably -SiH3.

[0027] The mass average molecular weight of the polysilazane is preferably 1,200 to 28,000, more preferably 1,500 to 25,000, from the viewpoints of solubility in a solvent and reactivity.

[0028] (Polycarbosilazane) The polycarbosilazane used in the present invention is not particularly limited in structure and can be selected from any suitable ones depending on the purpose. In the present invention, polycarbosilazane refers to one having a C-Si-N structure.

[0029] In a preferred embodiment, the polycarbosilazane used in the present invention comprises a repeating unit represented by the following formula (2-i) and a repeating unit represented by the following formula (2-ii). [ka] where: R 2a, R 2b , and R 2c are each independently a single bond, hydrogen, or C 1-4 It is alkyl, preferably a single bond or hydrogen. R 2d , R 2e and R 2f are each independently a single bond or hydrogen. However, R 2a , R 2b , R 2d and R 2e When is a single bond, it bonds to N in another repeating unit, and R 2c and R 2f When is a single bond, it bonds to Si contained in another repeating unit. n and m each independently represent 1 to 3, preferably 1 or 2, and more preferably 1. The polycarbosilazane is preferably polyperhydrocarbosilazane. 2a , R 2b , and R 2c is a single bond or hydrogen, and (CH2) in formula (2-i) n and (CH2) m In addition, it does not have a hydrocarbon group. The end groups of the polycarbosilazane are preferably -SiH3.

[0030] The polycarbosilazane used in the present invention preferably consists essentially of repeating units represented by formula (2-i) and repeating units represented by formula (2-ii). In the present invention, "substantially" means that 95% by mass or more of all the structural units contained in the polycarbosilazane are repeating units represented by formula (2-i) and repeating units represented by formula (2-ii). More preferably, the polycarbosilazane does not contain any repeating units other than the repeating units represented by formula (2-i) and repeating units represented by formula (2-ii).

[0031] In another preferred embodiment, the polycarbosilazane used in the present invention comprises a repeating unit represented by formula (2-iii). [ka] where: R 1 and R 2 are each independently a single bond, hydrogen, or C 1-4 R is an alkyl group or a linking group represented by the following formulas (a) to (c), and is preferably a single bond, hydrogen, or a linking group represented by the following formulas (a) to (c). 1 and R 2 When is a single bond, it is bonded to N contained in another repeating unit, and in the molecule, R 1 and R 2 At least two of the groups are linking groups represented by formulae (a) to (c). R 3 is a single bond, hydrogen, or C 1-4 R is alkyl, preferably a single bond or hydrogen. 3 When is a single bond, it is bonded to Si contained in another repeating unit.

[0032] The linking group represented by formula (a) is as follows: [ka] where: R a are each independently hydrogen, C 1-6 Alkyl, C 1-6 Alkenyl, or C 6-12 Aryl, preferably methyl, ethyl, vinyl, allyl, or phenyl. L a are each independently, C 2-8 Alkylene, or C 6-14 arylene, preferably C 2-6It is alkylene, more preferably -CH-CH- or -CH-CH-CH-. The methylene in the alkylene and arylene is unsubstituted or substituted with oxy, preferably unsubstituted. However, when substituted with oxy, the oxy does not directly bond to Si in formula (2-iii). na is 1 to 3, preferably 2 or 3, and more preferably 3. Of the bonds of the linking group of formula (a), the bonds that are not bonded to Si in formula (2-iii) are bonded to Si contained in another repeating unit.

[0033] The linking group represented by formula (b) is as follows: [ka] where: R b1 and R b2 are each independently hydrogen, C 1-6 Alkyl, C 1-6 Alkenyl, or C 6-12 It is aryl, preferably hydrogen or methyl. L b1 and L b2 are each independently, C 2-8 Alkylene, or C 6-14 arylene, preferably C 2-6 It is alkylene, more preferably -CH-CH- or -CH-CH-CH-. The methylene of alkylene and arylene is unsubstituted or substituted with oxy, preferably unsubstituted. However, when substituted with oxy, the oxy does not directly bond to Si in formula (2-iii). nb1 and nb2 each independently represent 1 to 2, and preferably 2. p and q each independently represent 1 to 3, preferably 1 or 2, and more preferably 1. Of the bonds of the linking group of formula (b), the bonds that are not bonded to Si in formula (2-iii) are bonded to Si contained in another repeating unit.

[0034] The linking group represented by formula (c) is as follows: [ka] R c1 and R c2 are each independently hydrogen, C 1-6 Alkyl, C 1-6 Alkenyl, or C 6-12 aryl, preferably C 1-6 It is alkyl, and more preferably methyl or ethyl. L c1 and L c2 are each independently, C 2-8 Alkylene, or C 6-14 arylene, preferably C 2-6 It is alkylene, more preferably -CH-CH- or -CH-CH-CH-. The methylene of alkylene and arylene is unsubstituted or substituted with oxy, preferably unsubstituted. However, when substituted with oxy, the oxy does not directly bond to Si in formula (2-iii). nc1 and nc2 each independently represent 1 to 3, and preferably 2. Of the bonds of the linking group of formula (c), the bonds that are not bonded to Si in formula (2-iii) are bonded to Si contained in another repeating unit.

[0035] The mass-average molecular weight of the polycarbosilazane according to the present invention is preferably sufficiently large to prevent evaporation of low-molecular-weight components and suppress volume change when filling fine trenches, while it is also preferably sufficiently low in viscosity to ensure sufficient coating properties and to fill trenches with high aspect ratios. For these reasons, the mass-average molecular weight of the polycarbosilazane is preferably 1,200 to 28,000, more preferably 1,500 to 25,000.

[0036] (Polysiloxazane) The polysiloxazane used in the present invention is not particularly limited in structure and can be selected from any suitable ones depending on the purpose. The polysiloxazane has a siloxane bond in the polysilazane main skeleton, and preferably contains a repeating unit represented by the following formula (3-i) and a repeating unit represented by the following formula (3-ii). [ka] (In the formula, R 3a , R 3b , R 3c , R 3d and R 3e are each independently a hydrogen atom, an alkyl group, an alkenyl group, a cycloalkyl group, or an aryl group, and R 3a and R 3b At least one of R is a hydrogen atom, 3d and R 3e at least one of which is a hydrogen atom) A siloxazane compound having a repeating unit represented by the formula: In the siloxazane compound, the ratio of O atoms to the total number of O atoms and N atoms is 5% or more and 25% or less; and The siloxazane compound was decoupling-decoupled by the inverse gate decoupling method. 29 In a spectrum obtained by Si-NMR, the ratio of the area of ​​the peak detected between -75 ppm and -90 ppm to the area of ​​the peak detected between -25 ppm and -55 ppm is 4.0% or less.

[0037] The polysiloxazane of the present invention preferably has a sufficiently high mass average molecular weight to prevent evaporation of low molecular weight components and suppress volume change when filling fine trenches, while also having a sufficiently low viscosity to ensure sufficient coating properties and to adequately fill trenches with high aspect ratios. For these reasons, the mass average molecular weight of the polysiloxazane is preferably 1,200 to 28,000, more preferably 1,500 to 25,000.

[0038] (solvent) The composition used in the present invention may contain a solvent. This solvent is selected from those that uniformly dissolve or disperse each component contained in the composition. Specific examples of the solvent include ethylene glycol monoalkyl ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, and ethylene glycol monobutyl ether; diethylene glycol dialkyl ethers such as diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dipropyl ether, and diethylene glycol dibutyl ether; ethylene glycol alkyl ether acetates such as methyl cellosolve acetate and ethyl cellosolve acetate; propylene glycol monomethyl ether (PGME); propylene glycol monoethyl ether (PGME); Examples of the propylene glycol monoalkyl ether include propylene glycol monomethyl ether acetate (PGMEA), propylene glycol alkyl ether acetates such as propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monoethyl ether acetate, and propylene glycol monopropyl ether acetate; aromatic hydrocarbons such as benzene, toluene, xylene, and mesitylene; ethers such as dipropyl ether, dibutyl ether, and anisole; ketones such as methyl ethyl ketone, acetone, methyl amyl ketone, methyl isobutyl ketone, and cyclohexanone; alcohols such as isopropanol and propanediol; and alicyclic hydrocarbons such as cyclooctane and decalin. Xylene, dibutyl ether, and propylene glycol monomethyl ether are preferred. These solvents can be used either alone or in combination of two or more. The content of the solvent is preferably 1 to 96 mass %, more preferably 20 to 85 mass %, based on the total mass of the composition.

[0039] The composition used in the present invention can be combined with further optional components as needed. Examples of optional components include surfactants. The content of optional components excluding the solvent in the entire composition is preferably 10% by mass or less, more preferably 5% by mass or less, based on the total mass of the composition.

[0040] The present invention will now be described with reference to examples, which are for illustrative purposes only and are not intended to limit the scope of the present invention.

[0041] In the following examples, the weight-average molecular weight (Mw) is measured by gel permeation chromatography (GPC) using polystyrene as the standard. GPC is performed using an alliance™ e2695 high-speed GPC system (Nihon Waters K.K.) and an organic solvent-based GPC column, Shodex KF-805L (Showa Denko K.K.). Measurements are performed using monodisperse polystyrene as the standard sample, chloroform as the developing solvent, at a flow rate of 0.6 mL / min and a column temperature of 40°C, and Mw is calculated as the molecular weight relative to the standard sample.

[0042] [Preparation of Polysilazane Intermediate A] After flushing the interior of a 10-L reaction vessel equipped with a cooling condenser, mechanical stirrer, and temperature controller with dry nitrogen, 7,500 ml of dry pyridine was added and cooled to -3°C. 500 g of dichlorosilane was then added, producing a white solid adduct (SiH2Cl2·2C5H5N). After confirming that the reaction mixture had cooled below -3°C, 350 g of ammonia was slowly bubbled into the mixture while stirring. After stirring for 30 minutes, dry nitrogen was bubbled into the liquid layer for 30 minutes to remove excess ammonia. The resulting slurry was pressure-filtered under a dry nitrogen atmosphere using a 0.2 μm Teflon® filter to obtain 6,000 ml of filtrate. The pyridine was removed using an evaporator, and xylene was added to obtain a 39.8% by mass xylene solution of polysilazane intermediate A. The resulting polysilazane intermediate A had a Mw of 1,200.

[0043] [Preparation of Polycarbosilazane-Containing Composition A] After flushing the interior of a 1-L reaction vessel equipped with a cooling condenser, mechanical stirrer, and temperature controller with dry nitrogen, 500 ml of dry pyridine was added and cooled to -3°C. Next, 9.67 g of dichlorosilane and 4.33 g of 1,1,3,3-tetrachloro-1,3-disilacyclobutane were added. After confirming that the reaction mixture had cooled to below 0°C, 10.3 g of ammonia was slowly bubbled into the mixture while stirring. After continuing stirring for 30 minutes, dry nitrogen was bubbled into the liquid layer for 30 minutes to remove excess ammonia. The resulting slurry product was pressure-filtered under a dry nitrogen atmosphere using a 0.2 μm Teflon® filter to obtain 400 ml of filtrate. After distilling off the pyridine from the filtrate, xylene was added to obtain 40.0 mass% polycarbosilazane-containing composition A (hereinafter sometimes referred to as composition A). The resulting polycarbosilazane had an Mw of 9,300.

[0044] [Preparation of Polycarbosilazane-Containing Composition B] A 200 mL three-neck flask equipped with a magnetic stirrer bar, nitrogen inlet, and reflux condenser was charged with 30.0 g of polysilazane intermediate A in xylene, 0.78 g of tetravinylsilane as a crosslinker in 8 g of toluene, and 0.68 g of azabisisobutyronitrile (AIBN) as a reaction initiator. Xylene was then added to the reaction solution to obtain a 20 wt% polysilazane intermediate A content. N2 was bubbled through the reaction solution (50 mL / min) for 10 minutes while stirring. The mixture was then heated at 80°C for 5 hours and concentrated under reduced pressure at 40°C to obtain a 40.0 wt% polycarbosilazane-containing composition B (hereinafter referred to as composition B). The resulting polycarbosilazane had an Mw of 12,500.

[0045] [Preparation of Polysilazane-Containing Composition C] 4710 g of dry pyridine, 150 g of dry xylene, and 1650 g of the 39.8 wt% xylene solution of polysilazane intermediate A obtained above were added, and the mixture was stirred to homogenize while bubbling with nitrogen gas at 0.5 NL / min. Subsequently, a modification reaction was carried out at 110°C for 10 hours to obtain 41.0 wt% polysilazane-containing composition C (hereinafter sometimes referred to as composition C). The resulting polysilazane had an Mw of 7,800.

[0046] [Preparation of Polysiloxazane-Containing Composition D] After purging the interior of a 10-L reaction vessel equipped with a cooling condenser, mechanical stirrer, and temperature controller with dry nitrogen, 2,800 g of dry pyridine and 400 g of a 39.8 wt% xylene solution of polysilazane intermediate were introduced and cooled to -5°C with stirring. A solution of 6 g of purified water dissolved in 1,000 g of dry pyridine was added dropwise over 3 hours with stirring to a mixture cooled to -5°C. After the dropwise addition, the solution was returned to room temperature and stirred for an additional hour. After distilling off the pyridine, xylene was added to obtain 19.8 wt% polysiloxazane-containing composition D (hereinafter sometimes referred to as composition D). The resulting polysiloxazane had an Mw of 5,800.

[0047] [Examples 1 and 2] Compositions A and B were each dropped onto a silicon wafer (8 inches) with a groove (2 μm wide, 20 μm long, and 13 μm deep) and spin-coated at 100 rpm to form a coating. The formed coating was thicker in the non-grooved areas and not flat. The excess coating in the non-grooved areas was removed. Next, the coating was pre-baked on a hot plate at 80°C for 90 seconds in an N2 atmosphere to dry the coating. The wafer was then exposed to an atmosphere containing 15.0 kPa NH3 and a water vapor partial pressure of 48.0 kPa at 100°C under atmospheric pressure for 30 minutes. Next, the wafer was heated in an 80% water vapor atmosphere (the remainder being O2) at 350°C for 60 minutes using a thermal diffusion furnace to obtain a siliceous film. Subsequently, the wafer was annealed at 850°C for 30 minutes in an N2 atmosphere. After the patterned substrate was returned to room temperature, the presence or absence of cracks was examined under an optical microscope in the grooved areas. Observe using a mirror. Figure 1 is an electron microscope photograph of a cross section of the grooved region of Example 1. From Figure 1, it can be seen that in Example 1, no cracks have occurred in the grooves and they are uniformly filled. The dry etching rate in the trench in Example 1 is 360 nm / min uniformly throughout the trench using inductively coupled plasma reactive ion etching (ICP-RIE) under the conditions of a pressure of 2.68 Pa, a power of 500 W, a bias of 200 W, Ar of 100 sccm, CHF of 326 sccm, and CF of 434 sccm.

[0048] [Example 3] Using Composition A, a coating film was formed in the same manner as in Example 1, the excess was removed, the coating was prebaked, and the coating film was dried. The wafer was then exposed to an atmosphere containing 15.0 kPa of NH3 and a water vapor partial pressure of 48.0 kPa at atmospheric pressure at 100°C for 30 minutes. Next, using a thermal diffusion furnace, the wafer was heated in an 80% water vapor atmosphere at 350°C for 60 minutes to obtain a siliceous film. Subsequently, annealing was performed in an N2 atmosphere at 850°C for 30 minutes. As above, the grooved area is observed to see if cracks have occurred.

[0049] [Example 4] Composition C was dropped onto a silicon wafer (8 inches) with a groove (0.15 μm wide, 2 mm long, and 3 μm deep) and spin-coated at a rotation speed of 100 rpm to form a coating. As described above, the excess was removed, pre-baked, and the coating was dried. The wafer was then exposed to an atmosphere containing 10.8 kPa NH3 and a water vapor partial pressure of 65.0 kPa at atmospheric pressure at 80°C for 30 minutes. Next, the wafer was heated in an 80% water vapor atmosphere at 350°C for 60 minutes using a thermal diffusion furnace to obtain a siliceous film. Subsequently, annealing was performed in an N2 atmosphere at 850°C for 30 minutes. As above, the grooved area is observed to see if cracks have occurred.

[0050] [Example 5] As in Example 4, a coating film was formed on a wafer, the excess was removed, and the wafer was dried. The wafer was then exposed to an atmosphere containing 2.3 kPa tetraethylammonium hydroxide and a water vapor partial pressure of 80.0 kPa at atmospheric pressure and 100°C for 30 minutes. Subsequently, the wafer was annealed in a N2 atmosphere at 850°C for 30 minutes to obtain a cured film. As above, the grooved area is observed to see if cracks have occurred.

[0051] [Example 6] Composition D is dropped onto a silicon wafer (8 inches) with a groove (0.02 μm wide, 2 mm long, and 0.5 μm deep) and spin-coated at a rotation speed of 1000 rpm to form a coating. As described above, excess is removed and the coating is dried. The wafer is then exposed to an atmosphere containing 22.0 kPa NH3 and a water vapor partial pressure of 32.0 kPa at atmospheric pressure at 120°C for 30 minutes. Next, the wafer is heated in an 80% water vapor atmosphere at 350°C for 60 minutes using a thermal diffusion furnace to obtain a siliceous film. Subsequently, annealing is performed in an N2 atmosphere at 850°C for 30 minutes. As above, the grooved area is observed to see if cracks have occurred.

[0052] [Comparative Examples 1 and 2] Using compositions A and B, a coating film was formed in the same manner as in Example 1, the excess was removed, the coating was prebaked, and the coating film was dried. The wafer was then exposed to an atmosphere of 48.0 kPa water vapor partial pressure (the remainder being N2) at 100°C under atmospheric pressure for 30 minutes. Next, using a thermal diffusion furnace, the wafer was heated in an 80% water vapor atmosphere at 350°C for 60 minutes to obtain a siliceous film. Subsequently, annealing was performed in an N2 atmosphere at 850°C for 30 minutes. As above, the grooved area is observed to see if cracks have occurred. Figure 2 is an electron microscope photograph of a cross section of the grooved region of Comparative Example 1. Figure 2 shows that in Comparative Example 1, cracks have occurred in the grooves and the grooves are not filled uniformly.

[0053] Comparative Example 3 Using Composition A, a coating film was formed in the same manner as in Example 1, the excess was removed, the coating was prebaked, and the coating film was dried. The coating film was then exposed to an atmosphere containing 15.0 kPa triethylamine and a water vapor partial pressure of 48.0 kPa at atmospheric pressure at 100°C for 30 minutes. Next, using a thermal diffusion furnace, the coating film was heated at 350°C in an 80% water vapor atmosphere for 60 minutes to obtain a siliceous film. Subsequently, annealing was performed in an N2 atmosphere at 850°C for 30 minutes. As above, the grooved area is observed to see if cracks have occurred.

[0054] Comparative Example 4 As in Example 4, a coating film was formed, excess portions were removed, and the coating film was pre-baked and dried. The wafer was then exposed to an atmosphere at atmospheric pressure, 80°C, and a water vapor partial pressure of 65.0 kPa for 30 minutes. Next, using a thermal diffusion furnace, the wafer was heated at 350°C in an 80% water vapor atmosphere for 60 minutes to obtain a siliceous film. Subsequently, annealing was performed in an N2 atmosphere at 850°C for 30 minutes. As above, the grooved area is observed to see if cracks have occurred.

[0055] Comparative Example 5 As in Example 4, a coating film was formed, excess material removed, prebaked, and dried. The wafer was then exposed to an atmosphere containing 10.8 kPa of triethylamine and a water vapor partial pressure of 65.0 kPa at atmospheric pressure and 80°C for 30 minutes. Next, the wafer was heated in a thermal diffusion furnace at 350°C in an 80% water vapor atmosphere for 60 minutes to obtain a siliceous film. Subsequently, annealing was performed in a N2 atmosphere at 850°C for 30 minutes. As above, the grooved area is observed to see if cracks have occurred.

[0056] Comparative Example 6 As in Example 6, a coating film was formed, excess material removed, prebaked, and dried. The wafer was then exposed to an atmosphere at atmospheric pressure, 120°C, and a water vapor partial pressure of 32.0 kPa for 30 minutes. Next, the wafer was heated in a thermal diffusion furnace at 350°C in an 80% water vapor atmosphere for 60 minutes to obtain a siliceous film. Subsequently, annealing was performed in a N2 atmosphere at 850°C for 30 minutes. As above, the grooved area is observed to see if cracks have occurred.

[0057] [Film thickness shrinkage rate] Each composition is applied to a 4-inch high-resistivity n-type Si wafer using a spin coater 1HDX2 (manufactured by Mikasa Co., Ltd.) and spin-dried to produce a coating film. The film thickness is measured using a spectroscopic ellipsometer M-2000V (manufactured by JA Woollam Co., Ltd.). Annealed films are prepared under the conditions of the examples and comparative examples, and the film thickness is measured. The film thickness shrinkage rate is calculated by dividing the difference between the coated film thickness and the film thickness after annealing by the coated film thickness. [Table 1]

Claims

1. A method for producing a siliceous membrane, comprising the following steps: (a) applying a siliceous film composition to a substrate having a groove to form a composition layer; (b) exposing the composition layer to an atmosphere containing a basic compound gas and water vapor; and (c) heating the substrate to harden the composition layer; comprising The method for producing a siliceous film, wherein the basic compound is ammonia, a quaternary ammonium compound, or any combination thereof.

2. The method of claim 1, wherein step (b) is carried out at 20 to 200°C.

3. 3. The method according to claim 1, wherein the partial pressure of the basic compound gas in step (b) is 2 to 50 kPa.

4. The method according to any one of claims 1 to 3, wherein the partial pressure of the water vapor in step (b) is 20 to 90 kPa.

5. The method according to any one of claims 1 to 4, wherein the siliceous film composition comprises a silicon-containing polymer selected from the group consisting of polysilazanes, polycarbosilazanes, and polysiloxazanes.

6. The method according to claim 5, wherein the silicon-containing polymer has a weight average molecular weight of 1,000 to 30,000.

7. 7. The method according to claim 5, wherein the content of the silicon-containing polymer is 10 to 100 mass % based on the total mass of the siliceous coating composition.

8. The method according to any one of claims 1 to 7, wherein the siliceous film composition contains a solvent.

9. The method according to any one of claims 1 to 8, further comprising the step of heating the substrate on which the composition layer has been formed to 50°C or higher between steps (a) and (b).

10. The method according to any one of claims 1 to 9, wherein the heating in step (c) is carried out at 200 to 1,000°C.

11. A siliceous film obtained by the method according to any one of claims 1 to 10.

12. An electronic device comprising the siliceous film of claim 11.

13. A method for producing an electronic device, comprising the method according to any one of claims 1 to 10.

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