Substrate processing method

Abstract

In one embodiment, the present invention provides a post-etching substrate processing method capable of dissolving a generated water-insoluble substance. In one embodiment, the present invention relates to a substrate processing method for processing an etched substrate, the method comprising a cleaning step for cleaning a substrate to be processed using an alkaline cleaning agent composition containing an alkaline compound and water and having a pH of 10 or more, the substrate to be processed is a substrate having a metal layer containing a Group 6 element metal, which has been etched using an etching solution containing phosphoric acid, nitric acid, water, and an organic amine.

Description

Technical Field

[0001] The invention relates to a method for processing a substrate after etching. Background Art

[0002] In the manufacturing process of semiconductor devices, for example, a process is performed in which an etched layer containing at least one metal such as tungsten, tantalum, zirconium, hafnium, molybdenum, niobium, ruthenium, osmium, rhenium, rhodium, copper, nickel, cobalt, titanium, titanium nitride, aluminum oxide, aluminum and iridium is etched to form a predetermined pattern shape.

[0003] In the semiconductor field in recent years, high integration has been advancing, requiring wiring to be more complex and miniaturized, and the requirements for pattern processing technology or etching liquid have also been increasing. Various etching methods have been proposed in the industry.

[0004] For example, Japanese Patent Application Publication No. 2013-237873 (Patent Document 1) proposes a method for etching at least one metal film having a metal thin film of molybdenum or a molybdenum alloy using an etching solution composition comprising phosphoric acid, nitric acid, a polyalkylene polyamine having three or more amino groups in one molecule, and water.

[0005] Japanese Patent Gazette No. 2019-165225 (Patent Document 2) proposes a method for etching tungsten-containing and TiN-containing materials using an etching solution composition comprising water; an oxidizing agent such as phosphoric acid and nitric acid; and at least one component selected from fluorine-containing etching compounds, organic solvents such as acetic acid, chelating agents, anti-corrosion agents such as polyethyleneimine, and surfactants.

[0006] Japanese Patent Application Laid-Open No. 2012-49535 (Patent Document 3) proposes a method for etching a multi-layer film such as a Cu / Mo stacked metal film using an etching solution composition containing 50 to 80 wt% of phosphoric acid, 0.5 to 10 wt% of nitric acid, 5 to 30 wt% of acetic acid, and 0.01 to 5 wt% of imidazole relative to the total weight of the composition. Summary of the invention

[0007] In one embodiment, the present invention relates to a substrate processing method, which is a method for processing an etched substrate, the method comprising a cleaning step of cleaning the substrate to be processed using an alkaline cleaning agent composition having a pH of 10 or above and containing an alkaline compound and water, wherein the substrate to be processed is a substrate having a metal layer containing a Group 6 element metal that has been etched using an etching solution containing phosphoric acid, nitric acid, water and an organic amine. DETAILED DESCRIPTION

[0008] After etching, water washing is usually performed to remove etching residues on the substrate. If water washing is performed after etching using an etching solution containing organic amines as described in Patent Documents 1 to 3, water-insoluble matter is generated and adheres to the substrate surface, causing filter clogging when the cleaning agent is circulated.

[0009] Therefore, in one embodiment, the present invention provides a method for treating a substrate after etching, which can dissolve the generated water-insoluble matter.

[0010] According to one embodiment of the present invention, a method for treating a substrate after etching that can dissolve generated water-insoluble matter can be provided.

[0011] In one embodiment, the present invention is based on the finding that generated water-insoluble substances can be dissolved by using a specific alkaline cleaning agent in cleaning a substrate after etching using an etching solution composition containing an organic amine.

[0012] In one embodiment, the present invention relates to a substrate processing method (hereinafter also referred to as "the substrate processing method of the present invention"), which is a method for processing an etched substrate, the method comprising a cleaning step of cleaning the substrate to be processed using an alkaline cleaning agent composition having a pH of 10 or above and containing an alkaline compound and water, wherein the substrate to be processed is a substrate having a metal layer containing a metal of a Group 6 element that has been etched using an etching solution containing phosphoric acid, nitric acid, water and an organic amine.

[0013] The details of the mechanism by which the effects of the present invention are expressed are not yet clear, but are presumed as follows.

[0014] In the etchant after etching treatment, heteropoly acid is generated based on dissolved Group 6 metal and phosphoric acid. The complex salt of the heteropoly acid as the product and the organic amine as the component of the etching solution is poorly soluble in water, so if the substrate to be processed is washed with water, water-insoluble matter is formed. In the present invention, it is believed that by using an alkaline cleaning agent composition containing an alkaline compound and water with a pH of 10 or above for cleaning, the dissociation (salt exchange) of the heteropoly acid and the organic amine and the decomposition (hydrolysis) of the heteropoly acid are promoted, and as a result, the water-insoluble matter can be removed (dissolved).

[0015] However, the present invention should not be construed as being limited to these mechanisms.

[0016] [Cleaning process]

[0017] The substrate processing method of the present invention includes a cleaning step (hereinafter also referred to as "cleaning step") of cleaning a substrate to be processed using an alkaline cleaning composition having a pH of 10 or above and containing an alkaline compound and water (hereinafter also referred to as "the alkaline cleaning composition of the present invention").

[0018] In the present invention, in one or more embodiments, the substrate processing method refers to a substrate cleaning method. That is, in one or more embodiments, the substrate processing method of the present invention is a substrate cleaning method comprising a cleaning step of using the alkaline cleaning agent composition of the present invention to clean the substrate to be processed.

[0019] In one or more embodiments, the cleaning step of using the alkaline cleaning composition of the present invention for cleaning is also referred to as an alkaline cleaning step.

[0020] Examples of the cleaning method in the cleaning step include immersion cleaning, ultrasonic cleaning, swing cleaning, spray cleaning, and cleaning by rotation of a spinner, etc. The cleaning methods may be performed alone or in combination of a plurality of them.

[0021] In the cleaning step, the temperature of the cleaning composition may be, for example, 0° C. or higher and 100° C. or lower.

[0022] In the above-mentioned washing step, the washing time is, for example, 10 seconds to 120 minutes.

[0023] In the cleaning step, ultrasonic waves may be irradiated when the cleaning composition and the substrate to be processed are in contact with each other. Examples of ultrasonic wave irradiation conditions include 20 to 5000 kHz.

[0024] Examples of an apparatus for performing the cleaning step include an immersion cleaner, an ultrasonic cleaner, a swing cleaner, a spray cleaner, and a cleaner utilizing rotation such as a spinner.

[0025] In one or more embodiments, the substrate processing method of the present invention may include a step of rinsing the processed substrate with water and drying the substrate after the cleaning step.

[0026] In one or more embodiments, the substrate processing method of the present invention may include a step of rinsing the processed substrate with water after the cleaning step.

[0027] In one or more embodiments, the substrate processing method of the present invention may include an etching process (hereinafter also referred to as "etching process") for etching a substrate (substrate to be processed) having a metal layer containing a Group 6 element metal using an etching solution containing phosphoric acid, nitric acid, water and organic amine.

[0028] Examples of the etching method in the etching step include immersion etching and single-wafer etching.

[0029] The temperature of the etching solution composition in the etching step (etching temperature) may be, for example, 0° C. or higher and 100° C. or lower.

[0030] The etching time in the etching step can be set to, for example, 1 minute or more and 180 minutes or less.

[0031] The etching solution used in the etching step is not particularly limited as long as it contains phosphoric acid, nitric acid, water, and an organic amine.

[0032] In one or more embodiments, the acid contained in the etching solution may be an acid containing phosphoric acid and nitric acid. That is, in one or more embodiments, the etching solution may further contain an acid other than phosphoric acid and nitric acid. Examples of the acid other than phosphoric acid and nitric acid include inorganic acids such as sulfuric acid and hydrochloric acid; and organic acids such as citric acid, formic acid, tartaric acid, oxalic acid, aminosulfonic acid, acetic acid, and malonic acid.

[0033] Examples of the organic amine compound contained in the etching solution include at least one organic amine compound selected from polyalkylene imine, a polymer having a structural unit derived from diallylamine, a polyalkylene polyamine, an alkylamine, an alkanolamine, an alicyclic amine, an aromatic amine, and an amino acid.

[0034] <Substrate to be processed>

[0035] In one or more embodiments, the substrate to be processed is a substrate having a metal layer containing a metal of a Group 6 element, which is etched using an etching solution containing phosphoric acid, nitric acid, water, and an organic amine.

[0036] In one or more embodiments, the metal layer etched by the etching solution composition is a metal layer containing a metal of Group 6. Examples of the metal of Group 6 include chromium (Cr), molybdenum (Mo), tungsten (W), and The metal layer may be a metal layer composed only of a metal of a Group 6 element, or may be a metal layer of an alloy containing a metal of a Group 6 element. Examples of the metal layer include a tungsten film and a molybdenum film. Examples of the thickness of the metal layer include 1 nm to 1 mm.

[0037] As the substrate to be processed, there can be mentioned a substrate having a tungsten film and a substrate having a molybdenum film. As the substrate, there can be mentioned at least one substrate selected from semiconductor wafers, substrates for liquid crystal display devices, substrates for plasma displays, substrates for FED (Field Emission Display), substrates for optical disks, substrates for magnetic disks, substrates for magneto-optical disks, substrates for photomasks, ceramic substrates, and substrates for solar cells.

[0038] <Alkaline cleaning agent composition>

[0039] The alkaline cleaning composition of the present invention is an aqueous cleaning composition having a pH of 10 or higher, containing an alkaline compound and water.

[0040] (Basic Compounds)

[0041] As the alkaline compound contained in the alkaline cleaning agent composition of the present invention, at least one of an inorganic base and an organic base can be cited. As the inorganic base, for example, ammonia; alkali metal hydroxides such as potassium hydroxide and sodium hydroxide, etc. can be cited. As the organic base, for example, organic amines such as tetramethylammonium hydroxide (TMAH) or salts thereof can be cited. Among them, from the perspective of the strength of its alkalinity, the alkaline compound preferably includes at least one selected from ammonia, alkali metal hydroxides, and organic amines or salts thereof. The alkaline compound can be one kind or a combination of two or more kinds.

[0042] From the viewpoint of improving the solubility of water-insoluble substances, the content of the alkaline compound in the alkaline cleaning agent composition of the present invention is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and more preferably 0.1% by mass or more, and from the viewpoint of improving the solubility of water-insoluble substances, preferably 100% by mass or less, more preferably 99% by mass or less, and more preferably 98% by mass or less. More specifically, the content of the alkaline compound in the alkaline cleaning agent composition of the present invention is preferably 0.01% by mass or more and 100% by mass or less, more preferably 0.05% by mass or more and 99% by mass or less, and more preferably 0.1% by mass or more and 98% by mass or less. In the case where the alkaline compound is a combination of two or more, the content of the alkaline compound is their total content.

[0043] (water)

[0044] Examples of the water contained in the alkaline cleaning composition of the present invention include distilled water, ion-exchanged water, pure water, and ultrapure water.

[0045] From the viewpoint of improving the solubility of water-insoluble substances, the content of water in the alkaline cleaning agent composition of the present invention is preferably 0% by mass or more, more preferably 1% by mass or more, and further preferably 2% by mass or more, and from the viewpoint of improving the solubility of water-insoluble substances, it is preferably 99.99% by mass or less, more preferably 99.95% by mass or less, and further preferably 99.90% by mass or less. More specifically, the content of water in the alkaline cleaning agent composition of the present invention is preferably 0% by mass or more and 99.99% by mass or less, more preferably 1% by mass or more and 99.95% by mass or less, and further preferably 2% by mass or more and 99.90% by mass or less.

[0046] (Other ingredients)

[0047] From the viewpoint of improving the cleaning property, the alkaline cleaning composition of the present invention may contain other components as required in addition to the alkaline compound and water. Examples of other components include surfactants, chelating agents, defoaming agents, alcohols, preservatives, antioxidants, and the like.

[0048] From the viewpoint of improving the solubility of water-insoluble substances, the pH of the alkaline cleaning composition of the present invention is 10 or more, preferably 11 or more, and preferably 14 or less. In the present invention, the pH of the alkaline cleaning composition is a value at 25° C., which can be measured using a pH meter, specifically, by the method described in the Examples.

[0049] The alkaline cleaning agent composition of the present invention can be prepared, for example, by mixing an alkaline compound, water, and other components as required using a known method. In the present invention, "mixing" includes mixing an alkaline compound, water, and other components as required simultaneously or in any order. In the method for preparing the alkaline cleaning agent composition of the present invention, the amount of each component mixed may be the same as the content of each component of the alkaline cleaning agent composition of the present invention described above.

[0050] In one or more embodiments of the present invention, "the content of each component in the cleaning composition" refers to the content of each component in the cleaning composition used in the cleaning step, that is, at the time of starting cleaning (at the time of use).

[0051] The alkaline cleaning composition of the present invention can be prepared as a concentrate with a reduced amount of water within a range that does not impair storage stability. From the viewpoint of transportation and storage, and from the viewpoint of storage stability, the concentrate of the alkaline cleaning composition of the present invention is preferably prepared as a concentrate with a dilution ratio of more than 10 times and less than 100 times. The concentrate of the alkaline cleaning composition of the present invention can be used by diluting with water in a manner such that each component becomes the above-mentioned content (i.e., the content during cleaning). In the present invention, "when in use" or "when cleaning" of the concentrate of the alkaline cleaning composition refers to the state of the concentrate of the alkaline cleaning composition after dilution. In the case where the alkaline cleaning composition of the present invention is a concentrate, the substrate processing method of the present invention may further include a dilution step of diluting the concentrate of the alkaline cleaning composition of the present invention.

[0052] The substrate processing method of the present invention may include a step of water cleaning (water rinsing) the substrate to be processed before the above-mentioned cleaning step (alkaline cleaning step) (hereinafter also referred to as "water cleaning step").

[0053] In one or more embodiments, the water cleaning step is a water rinsing step.

[0054] Examples of the aqueous composition used in the water washing step include water such as distilled water, ion exchanged water, pure water, and ultrapure water. The aqueous composition may contain a low boiling point organic solvent such as ethanol and isopropyl alcohol in addition to water.

[0055] The temperature of the aqueous composition in the water washing step is not limited, but is preferably 5° C. to 80° C., more preferably 10° C. to 60° C. Examples of the washing method in the water washing step include blowing, dipping, and coating by spraying.

[0056] As an embodiment of the substrate processing method of the present invention, there can be cited a substrate processing method, which includes: using an alkaline cleaning agent composition with a pH of 10 or above containing an alkaline compound and water to clean a substrate to be processed that has been etched using an etching solution containing phosphoric acid, nitric acid, water and an organic amine.

[0057] In one or more embodiments, the substrate processing method of the present invention can be used in the manufacturing process of electronic devices, especially electrode wiring used in semiconductor devices such as liquid crystal display devices, and semiconductor memories such as non-volatile memories including 3D-NAND flash memories.

[0058] In one or more embodiments, the substrate processing method of the present invention can be suitably used for forming a single-layer metal wiring or manufacturing a stacked metal wiring, thereby giving the side surface of the wiring a positive tapered shape with a good cross-sectional shape.

[0059] Example

[0060] The present invention is specifically described below by way of examples, but the present invention is not limited to these examples.

[0061] 1. Preparation of cleaning agent composition

[0062] (Alkaline cleaning agent compositions of Examples 1 to 7 and Comparative Examples 1 to 3)

[0063] The alkaline compounds and water shown in Table 1 were blended to have the pH shown in Table 1 to obtain alkaline cleaning agent compositions of Examples 1 to 7 and Comparative Examples 1 to 3. The pH of each alkaline cleaning agent composition is as shown in Table 1.

[0064] (Cleaning agent compositions of Comparative Examples 4 and 5)

[0065] In the cleaning compositions of Comparative Examples 4 and 5, water was used.

[0066] The following ingredients were used in the preparation of the cleaning composition.

[0067] (Basic Compounds)

[0068] Ammonia [manufactured by Kanto Chemical Co., Ltd.]

[0069] KOH: Potassium hydroxide [manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.]

[0070] TMAH: Tetramethylammonium hydroxide [manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.]

[0071] (water)

[0072] Water [Ultrapure water produced using a continuous pure water production device (Pureconti PC-2000VRL model) and a subsystem (Makuace KC-05H model) manufactured by Kurita Industry Co., Ltd.]

[0073] 2. Determination methods of various parameters

[0074] [pH of cleaning composition]

[0075] The pH of the cleaning composition at 25° C. is a value measured using a pH meter (manufactured by DKK Toa Co., Ltd.), and is a value obtained after the electrode of the pH meter is immersed in the etching solution for 1 minute.

[0076] 3. Evaluation

[0077] [Evaluation of dissolving power (solubility) of water-insoluble substances]

[0078] The evaluation of the dissolving power (solubility) of water-insoluble substances was performed based on the following experimental procedures.

[0079] (Examples 1 to 7, Comparative Examples 1 to 5)

[0080] In Examples 1 to 7 and Comparative Examples 1 to 5, the dissolving power (solubility) of water-insoluble substances was evaluated according to an experimental procedure assuming that the etched substrate was rinsed with water (water washing) and then washed with alkali.

[0081] <Experimental procedures>

[0082] 1) In a 30 mL glass bottle, 10 mL of an etching solution containing 62% by mass of phosphoric acid, 5% by mass of nitric acid, 12% by mass of water, 2% by mass of an organic amine, and 19% by mass of acetic acid and 50 mg of a metal powder as an etched component shown in Table 1 were placed, and a heating treatment (45°C, water bath) was performed until the metal powder was completely dissolved and the liquid became transparent. As the above-mentioned organic amine, polyethyleneimine [number average molecular weight: 600, EPOMIN SP-006 manufactured by Nippon Shokubai Co., Ltd.] was used.

[0083] 2) Place 0.2 g of the etching solution treated in 1) above and 10 mL of pure water in a 100 mL beaker and mix thoroughly.

[0084] 3) The mixed solution obtained in 2) above was centrifuged (10000 ppm, 10 minutes) and the supernatant was removed to recover the precipitate.

[0085] 4) For several tens of mg of the precipitate, 10 mL of the cleaning agent composition of Examples 1 to 7 and Comparative Examples 1 to 5 was added, and the solubility was visually confirmed. Specifically, the presence or absence of the Tyndall phenomenon based on red laser irradiation was used for judgment. If no red line was observed in the liquid, it was evaluated as having solubility (the generated water-insoluble matter could be dissolved), and recorded as A in Table 1. If a red line was observed in the liquid, it was evaluated as having no solubility, and recorded as B in Table 1.

[0086] [Evaluation of filter fluid permeability]

[0087] (Examples 1 to 7, Comparative Examples 1 to 5)

[0088] In Examples 1 to 7 and Comparative Examples 1 to 5, the filter liquid permeability was evaluated according to an experimental procedure assuming that the etched substrate was rinsed with water (water washing) and then washed with alkali.

[0089] <Experimental procedures>

[0090] 1) In a 30 mL glass bottle, 10 mL of an etching solution containing 62% by mass of phosphoric acid, 5% by mass of nitric acid, 12% by mass of water, 2% by mass of an organic amine, and 19% by mass of acetic acid and 50 mg of a metal powder as an etched component shown in Table 1 were placed, and a heating treatment (45°C, water bath) was performed until the metal powder was completely dissolved and the liquid became transparent. As the above-mentioned organic amine, polyethyleneimine [number average molecular weight: 600, EPOMIN SP-006 manufactured by Nippon Shokubai Co., Ltd.] was used.

[0091] 2) Place 50 g of pure water and 2.5 g of the etchant treated in 1) above into a 100 mL beaker and mix thoroughly.

[0092] 3) Fill the entire amount of the suspension obtained in 2) above into a syringe (60 mL, 3 cm in diameter) and install a filter with a pore size of 0.2 μm and a filter area of ​​4 cm 2 The filter [Advantec, hydrophilic PTFE 0.2 μm (pore size) filter, model: 25HP020AN] was used. The syringe was fixed to the cylinder, and the plunger of the syringe was pushed in at a fixed pressure of 0.2 MPa of air pressure (filtration pressure) to allow 50 mL of the suspension to pass completely.

[0093] 4) Remove the filter from the syringe after the liquid was passed through in 3) above, and fill the syringe with 50 mL of the cleaning agent composition in Table 1. Install the previously removed filter in the syringe, push the plunger of the syringe under a fixed pressure of 0.2 MPa of air pressure (filtration pressure), and pass the liquid again.

[0094] 5) Remove the filter from the syringe after the liquid was passed through in 4) above, and fill the syringe with 50 mL of pure water. Install the previously removed filter on the syringe again, and push the plunger of the syringe under a fixed pressure of 0.2 MPa of air pressure (filtration pressure). Measure the time until 50 mL of pure water is completely passed through, and calculate the liquid passing rate (g / min・cm 2 The results are shown in Table 1. The higher the value of the liquid flow rate, the better the liquid flow property of the filter can be evaluated (the generated water-insoluble matter can be dissolved).

[0095] [Evaluation of substrate cleaning performance]

[0096] (Examples 1 to 7, Comparative Examples 1 to 5)

[0097] The cleaning performance of the substrate was evaluated according to the following experimental procedure. The results are shown in Table 1.

[0098] <Experimental procedures>

[0099] 1) In a 30 mL glass bottle, 10 mL of an etching solution containing 62% by mass of phosphoric acid, 5% by mass of nitric acid, 12% by mass of water, 2% by mass of an organic amine, and 19% by mass of acetic acid and 50 mg of a metal powder as an etched component shown in Table 1 were placed, and a heating treatment (45°C, water bath) was performed until the metal powder was completely dissolved and the liquid became transparent. As the above-mentioned organic amine, polyethyleneimine [number average molecular weight: 600, EPOMIN SP-006 manufactured by Nippon Shokubai Co., Ltd.] was used.

[0100] 2) The substrate listed in the table and 1.0 g of the etching solution treated in 1) above were placed in a 100 mL beaker, and 50 mL of pure water was added thereto. At this time, a precipitate was generated and residue adhered to the substrate.

[0101] 3) The substrate with the precipitate attached thereto obtained in 2) above was placed in a 100 mL beaker, 50 mL of the cleaning composition of Examples 1 to 7 and Comparative Examples 1 to 5 was added thereto, and the solubility of the residue on the substrate was visually confirmed.

[0102] The results were as follows: A was the sample in which no residue was observed on the substrate within 3 minutes after immersion in the cleaning solution; B was the sample in which no residue was observed on the substrate after more than 3 minutes and less than 30 minutes; and C was the sample in which residue was still observed on the substrate after 30 minutes.

[0103] [Table 1]

[0104]

[0105] As shown in Table 1, it can be seen that Examples 1 to 7, which used a specific alkaline cleaning agent after the water rinsing step, all had good dissolving ability and could dissolve the generated water-insoluble matter. In addition, it can be seen that Examples 1 to 7 all had good filter permeability and could dissolve the water-insoluble matter. Furthermore, it can be seen that the substrates of Examples 1 to 7 had excellent cleaning properties and could dissolve the generated water-insoluble matter.

[0106] Industrial Applicability

[0107] The present invention provides a method for treating a substrate after etching, which can dissolve generated water-insoluble matter, and is useful in a method for manufacturing a large-capacity semiconductor memory.

Claims

1. A substrate processing method, which is a method for processing an etched substrate. The substrate processing method comprises: A cleaning step of cleaning the substrate to be processed using an alkaline cleaning composition having a pH of 10 or above and containing an alkaline compound and water, The substrate to be processed is a substrate having a metal layer containing a metal of a Group 6 element, which is etched using an etching solution containing phosphoric acid, nitric acid, water, and an organic amine.

2. The substrate processing method according to claim 1, wherein: The acid contained in the etching solution is an acid including phosphoric acid and nitric acid. 3 . The substrate processing method according to claim 1 , further comprising a step of washing the substrate to be processed with water before the washing step.

4. The substrate processing method according to any one of claims 1 to 3, wherein: The pH of the alkaline cleaning composition is 11 or higher.

5. The substrate processing method according to any one of claims 1 to 4, wherein: The alkaline compound in the alkaline cleaning composition includes at least one selected from ammonia, alkali metal hydroxides, and organic amines or salts thereof.

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