Etchant

Abstract

To provide an etchant capable of suppressing precipitation and adhesion of silica generated during an etching process to a silicon oxide film.SOLUTION: An etchant for removing a silicon nitride film from a substrate having a silicon nitride film and a silicon oxide film, includes a siloxane compound modified with a compound having an alkyleneoxy group, phosphoric acid, and water.SELECTED DRAWING: None

Description

Technical Field

[0001] The present disclosure relates to an etching solution for a silicon nitride film, an etching method using the same, and a method for manufacturing a semiconductor substrate.

Background Art

[0002] In the manufacturing process of semiconductor devices, a step of selectively etching and removing the silicon nitride film (hereinafter also referred to as "SiN film") from a substrate having a silicon nitride film (hereinafter also referred to as "SiN film") and a silicon oxide film (hereinafter also referred to as "SiO2 film") is performed. Conventionally, as a method for etching a SiN film, a method of etching using phosphoric acid at a high temperature of 150 degrees or more is known.

[0003] In recent years, in the semiconductor field, high integration has been progressing, and the wiring has become more complex and finer, and a method for increasing the ratio of the etching rate of the SiN film to the SiO2 film has been proposed (for example, Patent Documents 1 to 3).

[0004] Patent Document 1 proposes an etching composition containing a first inorganic acid, at least one silane inorganic acid salt produced by reacting a second inorganic acid with a silane compound, and a solvent. Patent Document 2 proposes an etching composition containing an inorganic acid, a siloxane compound, an ammonium-based compound, and a solvent. Patent Document 3 proposes an etching solution prepared by blending an organic phosphonic acid compound, phosphoric acid, and water.

[0005] Also, as a method for selectively removing the SiN film among the SiO2 film and the SiN film, for example, Patent Document 4 proposes a polishing liquid composition containing ceria-coated inorganic oxide particles, a silicone-containing compound having at least one group of an ethyleneoxy group (EO) and a propyleneoxy group (PO) and a substituted ethylenediamine group, a nonionic organic molecule having at least two hydroxyl groups, and a solvent.

Prior Art Documents

Patent Documents

[0006] [Patent Document 1] Japanese Patent Publication No. 2016-29717 [Patent Document 2] Japanese Patent Publication No. 2018-85513 [Patent Document 3] Japanese Patent Publication No. 2020-96162 [Patent Document 4] International Publication No. 2021 / 242755 [Overview of the initiative] [Problems that the invention aims to solve]

[0007] In recent years, the semiconductor field has seen increasing integration, requiring more complex and miniaturized wiring, and thus demanding more efficient removal of silicon nitride films. In particular, in the manufacturing process of 3D semiconductor devices such as 3D NAND flash memory, there is a need to further improve the ratio of the etching rate of the SiN film to the SiO2 film from the viewpoint of productivity and yield. Furthermore, in conventional etching methods using phosphoric acid at high temperatures of 150°C or higher, a portion of the SiN film decomposes into silicic acid (Si(OH)4) and ammonium phosphate ((NH4)3PO4), and a portion of the silicic acid undergoes a dehydration reaction to generate silica (SiO2), which then precipitates and adheres to the SiO2 film. In particular, there is a need for an etching solution that can suppress the deposition and adhesion of silica on the SiO2 film, even at high concentrations of silica generated during the etching process (e.g., 200 ppm).

[0008] Therefore, this disclosure provides an etching solution that can suppress the deposition and adhesion of silica generated during the etching process onto the silicon oxide film, an etching method using the same, and a method for manufacturing a semiconductor substrate. [Means for solving the problem]

[0009] This disclosure relates, in one embodiment, to an etching solution for a process of removing a silicon nitride film from a substrate having a silicon nitride film and a silicon oxide film, the etching solution comprising a siloxane compound modified with a compound having an alkylene oxy group, phosphoric acid, and water.

[0010] This disclosure relates, in one embodiment, to an etching method that includes a step of removing a silicon nitride film from a substrate having a silicon nitride film and a silicon oxide film using the etching solution of this disclosure.

[0011] This disclosure relates to a method for manufacturing a semiconductor substrate, comprising, in one embodiment, a step of removing a silicon nitride film from a substrate having a silicon nitride film and a silicon oxide film using an etching solution of the Disclosure, wherein the substrate is a substrate for use in semiconductors. [Effects of the Invention]

[0012] According to this disclosure, in one embodiment, an etching solution is provided that can suppress the deposition and adhesion of silica generated during the etching process onto the silicon oxide film. [Modes for carrying out the invention]

[0013] This disclosure relates to an etching solution (hereinafter also referred to as "the etching solution of this disclosure") for a step of removing a silicon nitride film from a substrate having a silicon nitride film and a silicon oxide film, wherein the etching solution contains a siloxane compound modified with a compound having an alkylene oxy group, phosphoric acid, and water. The etching solution of this disclosure can suppress the deposition and adhesion of silica to the silicon oxide film generated during the etching process.

[0014] Although the detailed mechanism of how the effects of this disclosure are realized is not clear, it is presumed to be as follows. In this disclosure, a siloxane compound modified with a compound having an alkylene oxy group, for example, a siloxane compound represented by formula (II), is adsorbed onto the surface of Si(OH)4, silica, or SiO2 film generated during the etching process. Furthermore, when adsorbed onto the SiO2 film surface, it is thought that the protective film effect suppresses the deposition and adhesion of silica, and when it adheres to silica, it is thought that the repulsion from the siloxane compound adsorbed on the SiO2 film surface suppresses the adhesion of silica. However, this disclosure does not have to be construed as being limited to these mechanisms.

[0015] The etching solution of this disclosure can be prepared in one or more embodiments by combining a siloxane compound modified with a compound having an alkylene oxy group, phosphoric acid, water, and optionally other components. That is, the etching solution of this disclosure is prepared in one or more embodiments by combining a siloxane compound modified with a compound having an alkylene oxy group, phosphoric acid, and water. In this disclosure, "composed of" means that in addition to a siloxane compound modified with an alkylene oxy group, phosphoric acid, and water, any other components may be included as needed. Furthermore, in this disclosure, the amount of each component in the etching solution can be interpreted as the content in the etching solution.

[0016] [Siloxane compounds modified with compounds containing alkylene oxy groups] The etching solutions of this disclosure contain, in one or more embodiments, siloxane compounds modified with compounds having alkylene oxy groups. The etching solutions of this disclosure contain, in one or more embodiments, siloxane compounds modified with compounds having alkylene oxy groups. The siloxane compounds modified with compounds having alkylene oxy groups may be used alone or in combination of two or more. Examples of alkylene oxy groups include at least one selected from ethylene oxy groups (EO) and propylene oxy groups (PO), and EO is preferred from the viewpoint of suppressing the deposition and adhesion of silica to the SiO2 film.

[0017] The siloxane compound modified with a compound having an alkyleneoxy group in the present disclosure is preferably a siloxane compound having a structure represented by the following formula (I), and more preferably a siloxane compound represented by the following formula (II) from the viewpoint of suppressing precipitation and adhesion to the SiO2 film of silica.

[0018]

Chemical formula

[0019]

Chemical formula

[0020] In the above formula (I) and formula (II), examples of the anionic group include a phosphonic acid group, a sulfate group, a carboxylic acid group, or a phosphoric acid group (-O-PO-(OH)2). From the viewpoint of suppressing precipitation and adhesion to the SiO2 film of silica, R in the above formula (I) and formula (II) is preferably an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or an anionic group, more preferably a methyl group, a methoxy group, or a phosphoric acid group, and even more preferably a phosphoric acid group. In formula (II) above, t / (s+t)×100 is preferably 4 or more, more preferably 7 or more, more preferably 10 or more, even more preferably 15 or more, even more preferably 20 or more, even more preferably 30 or more, even more preferably 40 or more, and preferably 100 or less, more preferably 80 or less, even more preferably 70 or less, and even more preferably 60 or less. From a similar viewpoint, t / (s+t)×100 is preferably 4 or more and 100 or less, and more preferably 7 or more and 100 or less. In formulas (I) and (II) above, from a similar viewpoint, t is preferably 1 to 50 and more preferably 1 to 30. In formulas (I) and (II) above, r is between 1 and 30, and from a similar viewpoint, is preferably between 1 and 25, and more preferably between 3 and 20.

[0021] The HLB of the siloxane compound modified with the alkylene oxy compound is preferably 4 or higher, more preferably 5 or higher, and even more preferably 10 or higher, from the viewpoint of suppressing the deposition and adhesion of silica to the SiO2 film. Here, HLB is a value defined as "7 + sum of hydrophilic group counts - sum of lipophilic group counts," using the number of groups determined by the functional group as described in Davis, JT; Proc. Intern. Congr. Surface Activity, 2nd, London, 1, 426 (1957).

[0022] Examples of siloxane compounds modified with the alkylene oxy compound include at least one selected from PEG-7 dimethicone phosphate (HLB: 14.6), PEG-3 dimethicone (HLB: 4.5), PEG-10 dimethicone (HLB: 4.5 or 14), and trisiloxane ethoxylate (HLB: 5.4).

[0023] From the viewpoint of suppressing the deposition and adhesion of silica to the SiO2 film, the amount of siloxane compound modified with the alkylene oxy group in the etching solution of this disclosure is preferably 0.03% by mass or more, more preferably 0.04% by mass or more, and even more preferably 0.05% by mass or more. Similarly, from the same viewpoint, it is preferably 0.2% by mass or less, more preferably 0.15% by mass or less, and even more preferably 0.1% by mass or less. Similarly, from the same viewpoint, the amount of siloxane compound modified with the alkylene oxy group in the etching solution of this disclosure is preferably 0.03% by mass or more and 0.2% by mass or less, more preferably 0.04% by mass or more and 0.15% by mass or less, and even more preferably 0.05% by mass or more and 0.1% by mass or less. When there is a combination of two or more siloxane compounds modified with the alkylene oxy group, the amount of siloxane compounds modified with the alkylene oxy group refers to the total amount of those compounds. From the viewpoint of improving the ratio of the etching rate of the silicon nitride film to the silicon oxide film (SiN / SiO2 selective rate ratio), the amount of the siloxane compound modified with the alkylene oxy group in the etching solution of this disclosure is preferably 0.01% by mass or more, more preferably 0.02% by mass or more, and still more preferably 0.03% by mass or more. Similarly, from the viewpoint of improving the ratio of the etching rate of the silicon nitride film to the silicon oxide film (SiN / SiO2 selective rate ratio), it is preferably 0.2% by mass or less, more preferably 0.1% by mass or less, still more preferably 0.08% by mass or less, and still more preferably 0.05% by mass or less. Similarly, from the viewpoint of improving the ratio of the etching rate of the silicon nitride film to the silicon oxide film (SiN / SiO2 selective rate ratio), it is preferably 0.2% by mass or less, more preferably 0.02% by mass or more and still more preferably 0.1% by mass or less, still preferably 0.03% by mass or more and still more preferably 0.03% by mass or more and still more preferably 0.05% by mass or less.

[0024] [phosphoric acid] From the viewpoint of improving the ratio of the etching rate of the silicon nitride film to the silicon oxide film (hereinafter also referred to as the "SiN / SiO2 selective rate ratio"), the amount of phosphoric acid blended in the etching solution of this disclosure is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more. Similarly, from the viewpoint of improving the ratio of the etching rate of the silicon nitride film to the silicon oxide film (hereinafter also referred to as the "SiN / SiO2 selective rate ratio"), it is preferably 95% by mass or less, more preferably 90% by mass or less, and even more preferably 85% by mass or less. Similarly, from the viewpoint of improving the ratio of the etching rate of the silicon nitride film to the silicon oxide film (hereinafter also referred to as the "SiN / SiO2 selective rate ratio"), it is preferably 50% by mass or more and 95% by mass or less, more preferably 70% by mass or more and 90% by mass or less, and even more preferably 80% by mass or more and 85% by mass or less.

[0025] [water] Examples of water contained in the etching solution of this disclosure include distilled water, ion-exchanged water, pure water, and ultrapure water. The amount of water in the etching solution of this disclosure is preferably 2% by mass or more, more preferably 5% by mass or more, even more preferably 7% by mass or more, preferably 30% by mass or less, more preferably 25% by mass or less, and even more preferably 20% by mass or less.

[0026] [High-temperature stabilizer] In one or more embodiments, the etching solution of this disclosure may further contain or be formulated with a high-temperature stabilizer, from the viewpoint of suppressing filter clogging during circulating use while maintaining the SiN / SiO2 selective rate ratio. Examples of high-temperature stabilizers include at least one selected from sulfonic acid compounds, maleic acid, and oxalic acid. Examples of sulfonic acid compounds include p-toluenesulfonic acid and benzenesulfonic acid.

[0027] [Organophosphonic acid compounds] In one or more embodiments, the etching solution of this disclosure may further contain or be formulated with an organic phosphonic acid compound from the viewpoint of improving the SiN / SiO2 selective rate ratio and / or further suppressing the deposition and adhesion of silica to the SiO2 film. Examples of organic phosphonic acid compounds from the viewpoint of improving the SiN / SiO2 selective rate ratio and suppressing the deposition and adhesion of silica to the SiO2 film include phosphate-based polymers such as polyvinylphosphonic acid (PVPA), alkylphosphonic acids, alkenylphosphonic acids, alkyl etherphosphonic acids, etc.

[0028] [Nonionic surfactants] In one or more embodiments, the etching solution of this disclosure may further contain or be compounded with a nonionic surfactant from the viewpoint of further suppressing the deposition and adhesion of silica to the SiO2 film. Examples of nonionic surfactants from the viewpoint of suppressing the deposition and adhesion of silica to the SiO2 film include polyoxyalkylene alkyl ethers, and at least one selected from polyoxyethylene lauryl ether, polyoxyethylene oleyl ether, and polyoxyethylene polyoxypropylene lauryl myristyl ether.

[0029] [Other ingredients] The etching solution of this disclosure may further contain or be formulated with other components, to the extent that the effects of this disclosure are not impaired. Examples of other components include acids other than phosphoric acid, chelating agents, surfactants other than the nonionic surfactants described above, solubilizers, preservatives, rust inhibitors, disinfectants, antibacterial agents, antioxidants, and the like.

[0030] [Method for manufacturing etching solution] This disclosure relates, in one embodiment, to a method for producing an etching solution (hereinafter also referred to as "the etching solution production method of this disclosure") which includes a step of blending a siloxane compound modified with the alkylene oxy compound, phosphoric acid, water, and optionally the above-mentioned optional components (hereinafter also referred to as the "blending step"). In this disclosure, "compounding" includes mixing a siloxane compound modified with the alkylene oxy compound, phosphoric acid, water, and optionally any of the above-mentioned components simultaneously or sequentially. The order of mixing is not particularly limited. The compounding can be carried out using a mixer such as a homomixer, homogenizer, ultrasonic disperser, and wet ball mill.

[0031] From the viewpoint of improving the SiN / SiO2 selective rate ratio, the pH of the etching solution of this disclosure is preferably 0.1 or higher, more preferably 0.2 or higher, even more preferably 0.3 or higher, and preferably 2 or lower, more preferably 1.5 or lower, and even more preferably 1 or lower. From a similar viewpoint, the pH of the etching solution of this disclosure is preferably 0.1 or higher and 2 or lower, more preferably 0.2 or higher and 1.5 or lower, and even more preferably 0.3 or higher and 1 or lower. In this disclosure, the pH of the etching solution is the value of the etching solution at 25°C at the time of use, and can be measured using a pH meter, specifically by the method described in the examples.

[0032] The etching solutions of this disclosure are, in one or more embodiments, for use in etching where the etching temperature is 110°C or higher and 250°C or lower.

[0033] The etching solution of this disclosure may be stored and supplied in a concentrated state, provided that its stability is not compromised. This is preferable because it reduces manufacturing and transportation costs. This concentrated solution can then be used in the etching process after being appropriately diluted with water, an aqueous phosphoric acid solution, or the like as needed. A dilution ratio of 5 to 100 times is preferred.

[0034] [kit] In one aspect, this disclosure relates to a kit for manufacturing the etching solution of this disclosure (hereinafter also referred to as the "Kit of this Disclosure"). Examples of the kits of this disclosure include a two-component etching solution containing, for example, a solution (first solution) containing a siloxane compound modified with a compound having an alkylene oxy group, and a solution (second solution) containing phosphoric acid, which are mixed separately before use. After the first and second solutions are mixed, they may be diluted with water or an aqueous phosphoric acid solution as needed. The first or second solution may contain all or part of the amount of water used to prepare the etching solution. The phosphoric acid contained in the second solution may be all or part of the amount of phosphoric acid used to prepare the etching solution. The first and second solutions may each contain the above-mentioned optional components as needed. According to the kit of this disclosure, an etching solution capable of suppressing the deposition and adhesion of silica to the SiO2 film generated during the etching process can be obtained.

[0035] [Substrate to be processed] In one or more embodiments, the substrate to be etched using the etching solution of this disclosure is a substrate having a silicon nitride film and a silicon oxide film. In one or more embodiments, the substrate having a silicon nitride film and a silicon oxide film may be a substrate having a three-dimensional structure in which a plurality of silicon nitride films and a plurality of silicon oxide films are alternately stacked. Examples of substrates include substrates for use in semiconductors and substrates for use in flat panel displays. Examples of silicon nitride films include nitride films formed by low-pressure chemical vapor deposition (LPCVD), plasma chemical vapor deposition (PECVD), atomic layer deposition (ALD), etc. Examples of silicon oxide films include oxide films formed by thermal oxidation, LPCVD, PECVD, ALD, etc. The etching solution of this disclosure can be suitably used in the manufacture of three-dimensional semiconductor devices such as three-dimensional NAND flash memory in one or more embodiments. For example, the etching solution of this disclosure can be used in one or more embodiments to etch a substrate having a three-dimensional structure in which multiple silicon nitride films and multiple silicon oxide films are alternately stacked.

[0036] [Etching method] This disclosure relates, in one embodiment, to an etching method (hereinafter also referred to as "the etching method of this disclosure") which includes a step of removing a silicon nitride film from a substrate having a silicon nitride film and a silicon oxide film using the etching solution of this disclosure (hereinafter also referred to as "etching step"). By using the etching method of this disclosure, the deposition and adhesion of silica generated during the etching process to the SiO2 film can be suppressed, thereby improving the productivity of semiconductor substrates with improved quality. The etching method and conditions in the etching process can be the same as those in the etching process in the semiconductor substrate manufacturing method of this disclosure described later.

[0037] [Manufacturing method for semiconductor substrates] This disclosure relates to a method for manufacturing a semiconductor substrate (hereinafter also referred to as "the semiconductor substrate manufacturing method of this disclosure"), which in one embodiment includes a step (etching step) of removing a silicon nitride film from a substrate having a silicon nitride film and a silicon oxide film using the etching solution of this disclosure, wherein the substrate is a substrate for use in semiconductors. According to the semiconductor substrate manufacturing method of this disclosure, the deposition and adhesion of silica generated during the etching process to the SiO2 film can be suppressed, which can result in the efficient manufacturing of high-quality semiconductor substrates.

[0038] In the etching process, examples of etching methods include immersion etching and single-wafer etching.

[0039] In the etching process, the etching temperature of the etching solution is preferably 110°C or higher, more preferably 120°C or higher, even more preferably 140°C or higher, even more preferably 150°C or higher, and preferably 250°C or lower, more preferably 230°C or lower, even more preferably 200°C or lower, and even more preferably 180°C or lower. From a similar viewpoint, the etching temperature of the etching solution is preferably 110°C or higher and 250°C or lower, more preferably 120°C or higher and 230°C or lower, even more preferably 140°C or higher and 200°C or lower, and even more preferably 150°C or higher and 180°C or lower.

[0040] In the etching process, the etching time can be set to, for example, preferably 30 minutes or more, more preferably 60 minutes or more, and preferably 270 minutes or less, more preferably 180 minutes or less.

[0041] In the etching process described above, the etching rate of the silicon nitride film is preferably 40 Å / min or more, more preferably 50 Å / min or more, and even more preferably 60 Å / min or more, from the viewpoint of improving productivity.

[0042] In the etching process described above, the etching rate of the silicon oxide film is preferably 1 Å / min or less, more preferably 0.5 Å / min or less, and even more preferably 0.3 Å / min or less, from the viewpoint of improving productivity.

[0043] In the etching process, the SiN / SiO2 selective rate ratio is preferably 150 or higher, more preferably 200 or higher, and even more preferably 300 or higher, from the viewpoint of improving productivity. [Examples]

[0044] The present disclosure will be specifically described below with reference to examples, but the present disclosure is not limited in any way by these examples.

[0045] 1. Preparation of etching solution (Examples 1-7 and Comparative Examples 1-4) Etching solutions (pH 0.45) for Examples 1-7 and Comparative Examples 1-4 were obtained by combining a siloxane compound or additive represented by formula (II) shown in Table 1 with an aqueous phosphoric acid solution and, if necessary, water. The amounts (mass %), effective content (siloxane compound or additive, phosphoric acid, and water) of each etching solution are shown in Table 1.

[0046] The following components were used to prepare the etching solution. (Siloxane compounds represented by formula (II)) PEG-7 dimethicone phosphate [PS-100 manufactured by Phoenix Chemical, HLB: 14.6] PEG-3 Dimethicone [Shin-Etsu Chemical Co., Ltd.'s "KF-6015", HLB: 4.5] PEG-10 Dimethicone [Shin-Etsu Chemical Co., Ltd.'s "KF-6017", HLB: 4.5] PEG-10 Dimethicone [Shin-Etsu Chemical Co., Ltd.'s "KF-6043", HLB: 14] Trisiloxane ethoxylate [SILWET L-77, manufactured by Biomedical Sciences, HLB: 5.4] (Additives) PVPA (Polyvinylphosphonic Acid) [Maruzen Petrochemical Co., Ltd.] 3-[[3-aminopropyl(dimethyl)silyl]oxy-dimethylsilyl]propan-1-amine [manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.] Dimethyldimethoxysilane [manufactured by Tokyo Chemical Industry Co., Ltd.] (phosphoric acid) Phosphoric acid aqueous solution [Phosphoric acid concentration 85%, manufactured by Phosphorus Chemical Industry Co., Ltd.]

[0047] 2. Measurement methods for each parameter [pH of etching solution] The pH value of the etching solution at 25°C was measured using a pH meter (manufactured by Toa DKK Co., Ltd.), and the value was obtained one minute after immersing the pH meter's electrode in the etching solution.

[0048] [Method for calculating r, s, and t of siloxane compounds represented by formula (II)] The denaturation rate and the number of moles of EO added r were calculated using an H-NMR (nuclear magnetic resonance apparatus), the average molecular weight was measured by size exclusion chromatography (SEC), and s and t were calculated from those values. <H-NMR Conditions> Apparatus: JNM-ESC400 (manufactured by JEOL Ltd.) Number of integrations: 8 times Relaxation waiting time: 30 s Pulse angle: 45° <SEC Conditions> Column: K-806L + K-806L (manufactured by Showa Denko KK) Eluent: 1 mmol / L formin DM20 / CHCl3 Flow rate: 1.0 mL / min Column temperature: 40°C Detector: RI Injection volume: 100 μL Molecular weight standard: Polystyrene

[0049] 3. Evaluation of the etching solution [Etching rate and selective rate ratio] Colloidal silica (PL-1, manufactured by Fuso Chemical Industry Co., Ltd.) was added to the etching solutions prepared for each composition (Examples 1 to 7 and Comparative Examples 1 to 4) so that the Si concentration was 200 ppm, and a 1 cm × 1 cm silicon nitride film wafer whose thickness of the silicon nitride film had been measured in advance was immersed and etched at 160°C to 170°C for 90 minutes. Then, after cooling and washing with water, the thickness of the silicon nitride film was measured again, and the difference was taken as the etching amount. For the measurement of the film thickness, an optical interference type film thickness measuring apparatus (SCREEN Co., Ltd., "Random Ace VM-100") was used. Also, as the silicon oxide film (SiO2 film), 1.5 cm × 1 cm of LP-TEOS was used, and the same conditions as for the silicon nitride film were carried out to obtain the etching amount of the silicon oxide film. The etching rate of the silicon nitride film, the etching rate of the silicon oxide film, and the selective rate ratio were calculated using the following formula. The calculation results are shown in Table 1. Furthermore, the etching rate of the silicon oxide film allows us to evaluate the inhibitory effect on the deposition and adhesion of silica to the silicon oxide film. If the etching rate of the silicon oxide film is negative, it can be determined that silica has deposited and adhered to the silicon oxide film. The closer the value is to 0 Å / min, the higher the inhibitory effect on the deposition and adhesion of silica to the silicon oxide film. Etching rate of silicon nitride film (SiN film) (Å / min) = Amount of silicon nitride film etched (Å) / 90 (min) Etching rate of silicon oxide film (SiO2 film) (Å / min) = Amount of silicon oxide film etched (Å) / 90 (min) Selection rate ratio = silicon nitride film etching rate / silicon oxide film etching rate

[0050] [Table 1]

[0051] As shown in Table 1, the etching solutions of Examples 1 to 7, which contained the siloxane compound represented by formula (II), showed suppressed deposition and adhesion of silica to the SiO2 film compared to Comparative Examples 1 to 4, which did not contain the siloxane compound represented by formula (II), and furthermore, the SiN / SiO2 selective rate ratio was improved. [Industrial applicability]

[0052] The etching solution of this disclosure is useful in a method for manufacturing semiconductor substrates for high density or high integration.

Claims

1. An etching solution for removing a silicon nitride film from a substrate having a silicon nitride film and a silicon oxide film, An etching solution comprising a siloxane compound modified with a compound having an alkyleneoxy group, phosphoric acid, and water.

2. 2. The etching solution according to claim 1, wherein the etching solution is a mixture of a siloxane compound modified with a compound having an alkyleneoxy group, phosphoric acid, and water.

3. 2. The etching solution according to claim 1, wherein the siloxane compound modified with a compound having an alkyleneoxy group is a siloxane compound having a structure represented by the following formula (I): 【Chemistry 1】 In the formula (I), R is an alkyl group having 1 to 5 carbon atoms, a hydroxyalkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or an anionic group. t is 1 to 50, and r is 1 to 30.

4. 2. The etching solution according to claim 1, wherein the siloxane compound modified with a compound having an alkyleneoxy group is a siloxane compound represented by the following formula (II): 【Chemistry 2】 In the formula (II), R is an alkyl group having 1 to 5 carbon atoms, a hydroxyalkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or an anionic group. t / (s+t)×100 is 4 or more, and r is 1 to 30.

5. The etching solution according to claim 3 or 4, wherein R in the formula (I) and the formula (II) is a methyl group, a methoxy group, or a phosphate group.

6. The etching solution according to claim 3 or 4, wherein R in the formula (I) and the formula (II) is a phosphate group.

7. The etching solution according to claim 1 or 2, wherein the pH of the etching solution is 2 or less.

8. 3. The etching solution according to claim 1, which is for use in etching at an etching temperature of 110° C. or higher and 250° C. or lower.

9. 3. An etching method comprising the step of removing a silicon nitride film from a substrate having a silicon nitride film and a silicon oxide film thereon, using the etching solution according to claim 1.

10. The method includes a step of removing a silicon nitride film from a substrate having a silicon nitride film and a silicon oxide film by using the etching solution according to claim 1 or 2, The method for manufacturing a semiconductor substrate, wherein the substrate is a substrate for use in a semiconductor.

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