Method for filtering etching solution composition

Abstract

To provide a filtration method for an etchant composition that improves filtration speed while suppressing a change in concentration of components contained in the etchant composition even after filtration at a temperature of 30°C or higher, a manufacturing method and an etching method.SOLUTION: The filtration method includes the step for filtering at a temperature of 30°C or higher an etchant composition for etching a metal film formed on a substrate. The etchant composition contains phosphoric acid, nitric acid, organic acid whose solubility in water at 20°C is equal to or less than 900 g / L, etching inhibitor, and water. The blending amount of the organic acid in the etchant composition is equal to or greater than 10 mass% and equal to or less than 70%. The filtration system includes a tank 1 for storing the etchant composition, a pump 2 for pumping the etchant composition, a filter 3 for filtering the etchant composition, an outlet valve 4 for controlling the flow rate discharged from an outlet 5, a piping P1 connecting the above parts, a circulation route P2 branching from the piping and connecting upstream of the pump, and a circulation valve 7 for controlling the flow rate of the etchant composition being circulated.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This disclosure relates to a method for filtering an etching solution composition, a method for producing an etching solution composition, and an etching method. [Background technology]

[0002] In the manufacturing process of semiconductor devices, a process is carried out to etch a film containing at least one metal, such as tungsten, tantalum, zirconium, hafnium, molybdenum, niobium, ruthenium, osmium, rhenium, rhodium, copper, nickel, cobalt, titanium, titanium nitride, alumina, aluminum, and iridium, into a predetermined pattern shape. A mixed acid aqueous solution containing phosphoric acid, nitric acid, and acetic acid is commonly used as the etching solution. In recent years, the semiconductor field has seen increasing integration, leading to a demand for more complex and miniaturized wiring. This has resulted in growing demands for pattern processing technology and etching solutions, and various etching solution compositions have been proposed.

[0003] For example, Patent Document 1 proposes an etching solution composition containing phosphoric acid, nitric acid, methoxyacetic acid, and water as an etching solution composition for etching a metal thin film mainly composed of silver. Patent Document 2 proposes an etching solution composition for etching metal oxides containing indium or metal oxides containing zinc and indium, comprising at least one basic acid (such as phosphoric acid or nitric acid) and water, wherein the acid dissociation constant pKa at 25°C in any of the basic acid dissociation stages is 2.15 or less, and the hydrogen ion concentration pH at 25°C is 4 or less. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2006-253473 [Patent Document 2] Japanese Patent Publication No. 2015-60937 [Overview of the project] [Problems that the invention aims to solve]

[0005] The presence of foreign matter in the etching solution composition can lead to a deterioration in the cleanliness of the substrate after etching. Therefore, etching solution compositions are usually filtered before use. If the etching solution has high viscosity, the filtration rate is slow and productivity is low. However, the viscosity of the etching solution can be reduced by increasing the filtration temperature. However, if the etching solution contains volatile compounds such as acetic acid, these compounds will volatilize during high-temperature filtration, changing their concentration and making it difficult to maintain the etching solution composition as originally designed. When the etching solution composition changes, there is a problem in that the etching performance cannot be maintained.

[0006] Therefore, in one embodiment, this disclosure provides a method for filtering an etching solution composition that can improve the filtration rate while suppressing changes in the concentration of components contained in the etching solution composition even when filtered at a temperature of 30°C or higher. [Means for solving the problem]

[0007] This disclosure relates to a method for filtering an etching solution composition, in one embodiment, comprising the step of filtering the etching solution composition for etching a metal film formed on a substrate at a temperature of 30°C or higher, wherein the etching solution composition contains phosphoric acid, nitric acid, an organic acid having a solubility in water at 20°C of 900 g / L or less, an etching inhibitor, and water, and the amount of the organic acid in the etching solution composition is 10% by mass or more and 70% by mass or less.

[0008] This disclosure relates to a method for producing an etching solution composition, in one embodiment, which includes a step of filtering an etching solution composition for etching a metal film formed on a substrate at a temperature of 30°C or higher, wherein the etching solution composition contains phosphoric acid, nitric acid, an organic acid having a solubility in water at 20°C of 900 g / L or less, an etching inhibitor, and water, and the amount of the organic acid in the etching solution composition is 10% by mass or more and 70% by mass or less.

[0009] This disclosure relates to an etching method, in one embodiment, which includes the step of etching a metal film formed on a substrate using an etching solution composition obtained by filtering at a temperature of 30°C or higher, wherein the etching solution composition contains phosphoric acid, nitric acid, an organic acid having a solubility in water at 20°C of 900 g / L or less, an etching inhibitor, and water, and the amount of the organic acid in the etching solution composition is 10% by mass or more and 70% by mass or less. [Effects of the Invention]

[0010] According to this disclosure, in one embodiment, a method for filtering an etching solution composition is provided that can improve the filtration rate while suppressing changes in the concentration of components contained in the etching solution composition even when filtered at a temperature of 30°C or higher. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a schematic diagram showing one embodiment of the filling system. [Modes for carrying out the invention]

[0012] This disclosure is based on the finding that, in one embodiment, by using an etching solution containing phosphoric acid, nitric acid, an organic acid with a solubility in water at 20°C of 900 g / L or less, an etching inhibitor, and water, it is possible to improve the filtration rate while suppressing changes in the concentration of components contained in the etching solution composition even when filtered at high temperatures (30°C or higher).

[0013] In one aspect, the present disclosure relates to a method for filtering an etching solution composition (hereinafter, also referred to as "the pre-filtering etching solution composition of the present disclosure") for etching a metal film formed on a substrate at a temperature of 30 °C or higher (hereinafter, also referred to as "the filtering step"). The etching solution composition contains phosphoric acid, nitric acid, an organic acid having a solubility in water at 20 °C of 900 g / L or less, an etching inhibitor, and water. The blending amount of the organic acid in the etching solution composition is 10% by mass or more and 70% by mass or less. According to the filtering method of the present disclosure, even when filtering at a temperature of 30 °C or higher, the change in the concentration of the components contained in the etching solution composition can be suppressed while improving the filtering rate.

[0014] Although the details of the mechanism of the present disclosure for expressing the effect are not clear, it is presumed as follows An organic acid having a solubility in water of 900 g / L or less (for example, methoxyacetic acid) is less volatile even at a temperature of 30 °C or higher than an organic acid having a solubility in water exceeding 900 g / L (for example, acetic acid). In the present disclosure, by using a predetermined amount of an organic acid having a solubility in water of 900 g / L or less as the organic acid, it is considered that the change in the concentration of the components contained in the etching solution composition can be suppressed even when filtering at a temperature of 30 °C or higher, and the viscosity of the etching solution composition can be reduced. And, by reducing the viscosity of the etching solution composition, it is considered that the filtering rate becomes higher and the productivity can be improved. However, the present disclosure may not be construed as being limited to these mechanisms.

[0015] [Filtering Step] The filtering method of the present disclosure includes a step of filtering an etching solution composition (the pre-filtering etching solution composition of the present disclosure) for etching a metal film formed on a substrate at a temperature of 30 °C or higher (the filtering step). The etching solution composition obtained in the filtering step (the post-filtering etching solution composition) can be used for etching as it is in one or more embodiments.

[0016] The filtration step, in one or more embodiments, includes filtration using a filter. Examples of filters include conventionally used pleated filters, depth filters, and filters containing filter aids, and these can be used in combination. From the viewpoint of improving the filtration speed, pleated filters are preferred, more preferably a combination of a depth filter and a pleated filter, and a filter containing a filter aid may also be added. In one or more embodiments, when a filter containing a filter aid is used, it is preferable to provide a pleated filter in the subsequent stage. As pleated filters, generally, those made by shaping the filter material into pleats and forming a hollow cylindrical cartridge type can be used (e.g., Advantec Toyo, Nippon Pall, CUNO, Daiwabo, 3M, Entegris, Cobetter, etc.). Unlike depth filters, which collect particles in each part along the thickness direction, pleated filters have a thinner filter material and are said to primarily collect particles on the filter surface, and are generally characterized by high filtration accuracy. Pleated filters may be used in a single stage or in multiple stages (for example, in a series arrangement). Specific examples of depth-type filters include bag-type filters (Sumitomo 3M, etc.) and cartridge-type filters (Advantec Toyo, Nippon Pall, CUNO, Daiwabo, etc.). A depth-type filter is a filter characterized by a pore structure in the filter material that is coarse at the inlet side and fine at the outlet side, and that becomes continuously or gradually finer from the inlet side to the outlet side. Therefore, large particles in the etching solution composition are collected near the inlet side, and small particles are collected near the outlet side. Examples of depth-type filters include bag-type filters and hollow cylindrical cartridge-type filters. Furthermore, a filter material having the above characteristics that is simply molded into a pleated shape is classified as a depth-type filter because it has the function of a depth-type filter. Depth-type filters may be used in a single stage, in a multi-stage combination (for example, in a direct arrangement), or in a multi-stage combination of filters with different pore sizes in order of increasing pore size. In addition, bag-type and cartridge-type filters may be used in combination. A filter containing a filter aid is a filter containing a filter aid. Examples of the filter aid include insoluble mineral substances such as silicon dioxide, kaolin, acid clay, diatomaceous earth, perlite, bentonite, and talc. Among the above filter aids, from the viewpoint of improving dispersibility, silicon dioxide, diatomaceous earth, and perlite are preferred, diatomaceous earth and perlite are more preferred, and diatomaceous earth is even more preferred. The filter containing a filter aid can contain the filter aid either on one or both of the filter surface and the interior of the filter.

[0017] As the filtration temperature in the filtration step, from the viewpoint of improving the filtration rate, it is 30°C or higher, preferably 35°C or higher, more preferably 40°C or higher, and from the viewpoint of the volatility of the etching liquid composition, it is preferably 80°C or lower, more preferably 75°C or lower, and even more preferably 70°C or lower. More specifically, the filtration temperature is preferably 30°C or higher and 80°C or lower, more preferably 35°C or higher and 75°C or lower, and even more preferably 40°C or higher and 70°C or lower. In the present disclosure, the filtration temperature refers to the temperature of the etching liquid composition during filtration.

[0018] As the filtration pressure in the filtration step, from the viewpoint of productivity, it is preferably 0.1 MPa or higher and 0.5 MPa or lower, more preferably 0.15 MPa or higher and 0.45 MPa or lower, and even more preferably 0.2 MPa or higher and 0.4 MPa or lower.

[0019] As the filtration rate in the filtration step, from the viewpoint of productivity, it is preferably 0.1 kg / (m 2 , 2 ,

[0019] , 2 , , 2 , 2 , , 2 , 2 , 2 ·min) or higher, more preferably 1 kg / (m 2 ·min) or higher, even more preferably 2 kg / (m 2 ·min) or higher, and from the viewpoint of reducing the number of particles in the liquid, it is preferably 30 kg / (m 2 ·min) or lower, more preferably 20 kg / (m 2 ·min) or lower, and even more preferably 15 kg / (m 2 ·min) or lower. More specifically, the filtration rate is preferably 0.1 kg / (m 2 ·min) or higher and 30 kg / (m 2 ·min) or lower, and 1 kg / (m2 · min) or more and 20 kg / (m 2 · min) or less is more preferable, and 2 kg / (m 2 · min) or more and 15 kg / (m 2 · min) or less is even more preferable. The "filtration rate" in the present disclosure is the weight per unit area per unit time of filtration, and in one or more embodiments, it can be adjusted by adjusting the filtration pressure. When filtering using multiple filters, it is the weight per unit area per unit time of filtration calculated from the total sum of the areas of all the filters used.

[0020] As the filtration method in the filtration step, a cyclic method of repeated filtration may be used, or a one-pass method may be used. Also, a batch method of repeating the one-pass method may be used. As the liquid passing method, in order to apply pressure, a pump is preferably used in the cyclic method, and in addition to using a pump in the one-pass method, a pressure filtration method with a small variation range of the filter inlet pressure by introducing pneumatic pressure or the like into the tank can be used.

[0021] [Etching solution composition before filtration] The etching solution composition before filtration of the present disclosure contains phosphoric acid, nitric acid, an organic acid having a solubility in water at 20 °C of 900 g / L or less, an etching inhibitor, and water.

[0022] (Phosphoric acid) The blending amount of phosphoric acid in the etching solution composition before filtration of the present disclosure is preferably 1% by mass or more, more preferably 3% by mass or more, even more preferably 5% by mass or more, from the viewpoints of etching rate, storage stability, and improvement of filtration rate, and preferably 90% by mass or less, more preferably 70% by mass or less, even more preferably 60% by mass or less, from the viewpoint of improvement of filtration rate. More specifically, the blending amount of phosphoric acid in the etching solution composition before filtration of the present disclosure is preferably 1% by mass or more and 90% by mass or less, more preferably 3% by mass or more and 70% by mass or less, even more preferably 5% by mass or more and 60% by mass or less.

[0023] (Nitric acid) From the viewpoint of improving the etching rate, the amount of nitric acid in the pre-filtered etching solution composition of this disclosure is preferably 0.5% by mass or more, more preferably 1% by mass or more, even more preferably 1.5% by mass or more, even more preferably 2% by mass or more, even more preferably 3% by mass or more, and even more preferably 4% by mass or more. From the viewpoint of reducing etching unevenness, it is preferably 20% by mass or less, more preferably 10% by mass or less, even more preferably 7% by mass or less, and even more preferably 6% by mass or less. More specifically, the amount of nitric acid in the pre-filtered etching solution composition of this disclosure is preferably 0.5% by mass or more and 20% by mass or less, more preferably 1% by mass or more and 10% by mass or less, even more preferably 1.5% by mass or more and 7% by mass or less, even more preferably 2% by mass or more and 6% by mass or less, even more preferably 3% by mass or more and 6% by mass or less, and even more preferably 4% by mass or more and 6% by mass or less.

[0024] (organic acid) The organic acid included in the pre-filtration etching solution composition of this disclosure, having a solubility of 900 g / L or less in water at 20°C, can be at least one selected from alkoxycarboxylic acids, hydroxy acids, aliphatic polycarboxylic acids, and alkoxyacetic acid esters, from the viewpoint of improving the filtration rate while suppressing changes in the concentration of components contained in the etching solution composition. Examples of the alkoxycarboxylic acid include methoxyacetic acid (solubility: 485 g / L). Examples of the hydroxy acid mentioned above include citric acid (solubility: 592 g / L). Examples of the aliphatic polycarboxylic acid include succinic acid (solubility: 58 g / L). Examples of the alkoxyacetic acid ester include 3-methoxybutyl acetate (solubility: 4.6 g / L). Organic acids with a solubility of 900 g / L or less in water at 20°C may be used individually or in combination of two or more.

[0025] The amount of organic acid with a solubility of 900 g / L or less in water at 20°C in the pre-filtration etching solution composition of this disclosure is preferably 10% by mass or more, preferably 20% by mass or more, and more preferably 30% by mass or more, from the viewpoint of suppressing changes in the concentration of components contained in the etching solution composition while improving the filtration rate, and preferably 70% by mass or less, preferably 65% ​​by mass or less, and more preferably 60% by mass or less, from the viewpoint of suppressing the rate of decrease in the concentration of organic acid. More specifically, the amount of organic acid with a solubility of 900 g / L or less in water at 20°C in the pre-filtration etching solution composition of this disclosure is preferably 10% by mass or more and 70% by mass or less, preferably 20% by mass or more and 65% by mass or less, and more preferably 30% by mass or more and 60% by mass or less. When there is a combination of two or more organic acids with a solubility of 900 g / L or less in water at 20°C, the amount of organic acid with a solubility of 900 g / L or less in water at 20°C is the total amount of those combined.

[0026] The total amount of phosphoric acid, nitric acid, and organic acids with a solubility of 900 g / L or less in water at 20°C in the pre-filtration etching solution composition of this disclosure is preferably 70% by mass or more, more preferably 75% by mass or more, even more preferably 80% by mass or more, and from the viewpoint of suppressing changes in the concentration of components contained in the etching solution composition while improving the filtration rate, is preferably 98% by mass or less, more preferably 95% by mass or less, and even more preferably 90% by mass or less. The total amount of phosphoric acid, nitric acid, and organic acids with a solubility of 900 g / L or less in water at 20°C in the pre-filtration etching solution composition of this disclosure is preferably 70% by mass or more and 98% by mass or less, more preferably 75% by mass or more and 95% by mass or less, and even more preferably 80% by mass or more and 90% by mass or less.

[0027] (Etching inhibitor) The etching inhibitor contained in the pre-filtration etching solution composition of this disclosure is, in one or more embodiments, an amine compound that does not have a carboxyl group, and includes, for example, at least one selected from polyalkylene imines and polyalkylene polyamines. Examples of the polyalkylene imines include polyethyleneimine (PEI). Examples of the polyalkylene polyamines include pentaethylenehexamine, diethylenetriamine, triethylenetetramine, and tetraethylenepentamine. The etching inhibitor may be used alone or in combination of two or more.

[0028] When the etching inhibitor is a polyalkylene imine, the number-average molecular weight of the etching inhibitor is preferably 300 or more, more preferably 600 or more, and even more preferably 1,200 or more, from the viewpoint of reducing etching unevenness, storage stability, and improving filtration rate. From the viewpoint of viscosity, it is preferably 100,000 or less, more preferably 5,000 or less, and even more preferably 3,000 or less. More specifically, the number-average molecular weight of the etching inhibitor is preferably 300 to 100,000, more preferably 600 to 5,000, and even more preferably 1,200 to 3,000. When the etching inhibitor is a polyalkylene polyamine, the weight-average molecular weight of the etching inhibitor is preferably 50 or more, more preferably 80 or more, and even more preferably 100 or more, from the viewpoint of reducing etching unevenness and maintaining storage stability and filterability. Similarly, it is preferably 1,000 or less, more preferably 500 or less, and even more preferably 300 or less. More specifically, the weight-average molecular weight of the etching inhibitor is preferably 50 or more and 1,000 or less, more preferably 80 or more and 500 or less, and even more preferably 100 or more and 300 or less.

[0029] The average molecular weight of compounds such as etching inhibitors used in this disclosure can be measured by gel permeation chromatography (GPC). An example of a method for measuring the average molecular weight of the etching inhibitor of this disclosure is shown below. <GPC Conditions (Polyalkyleneimine)> Sample solution: Adjusted to a concentration of 0.1 wt% Apparatus / Detector: HLC-8320GPC (Integrated GPC) manufactured by Tosoh Corporation Column: α-M + α-M (manufactured by Tosoh Corporation) Eluent: 0.15 mol / L Na2SO4, 1% CH3COOH / water Column temperature: 40 °C Flow rate: 1.0 mL / min Sample solution injection volume: 100 μL Standard polymer: Pullulan with known molecular weight (Shodex P-5, P-50, P-200, P-800)

[0030] The compounding amount of the etching inhibitor in the pre-filtration etching liquid composition of the present disclosure is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, still more preferably 0.5% by mass or more, and from the viewpoints of reducing etching unevenness, storage stability, and improving filtration rate, 10% by mass or less is preferable, 5% by mass or less is more preferable, 3% by mass or less is still more preferable, and 2% by mass or less is still more preferable. More specifically, the compounding amount of the etching inhibitor in the pre-filtration etching liquid composition of the present disclosure is preferably 0.01% by mass or more and 10% by mass or less, more preferably 0.1% by mass or more and 5% by mass or less, still more preferably 0.5% by mass or more and 3% by mass or less, and still more preferably 0.5% by mass or more and 2% by mass or less. When the etching inhibitor is a combination of two or more kinds, the compounding amount of the etching inhibitor is the total compounding amount thereof.

[0031] (Water) The pre-filtration etching liquid composition of the present disclosure contains water in one or more embodiments. Examples of the water contained in the pre-filtration etching liquid of the present disclosure include distilled water, ion-exchanged water, pure water, and ultrapure water. From the viewpoint of improving the filtration rate, the amount of water in the pre-filtration etching solution composition 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, and even more preferably 10% by mass or more. Similarly, from the viewpoint of improving the filtration rate, it is preferably 35% by mass or less, more preferably 30% by mass or less, even more preferably 25% by mass or less, and even more preferably 20% by mass or less. More specifically, the amount of water in the pre-filtration etching solution composition of this disclosure is preferably 2% by mass or more and 35% by mass or less, more preferably 5% by mass or more and 30% by mass or less, even more preferably 7% by mass or more and 25% by mass or less, and even more preferably 10% by mass or more and 20% by mass or less.

[0032] (Other ingredients) The pre-filtration etching solution composition of this disclosure may further contain other components, to the extent that the effects of this disclosure are not impaired. Examples of other components include inorganic acids other than phosphoric acid and nitric acid, organic acids other than organic acids with a solubility in water at 20°C of 900 g / L or less, chelating agents, surfactants, solubilizers, preservatives, rust inhibitors, disinfectants, antibacterial agents, antioxidants, and the like. In one or more embodiments, the pre-filtration etching solution composition of the present disclosure may contain a combination of an organic acid having a solubility of 900 g / L or less in water at 20°C and an organic acid having a solubility of 900 g / L or more in water at 20°C. Examples of organic acids having a solubility of 900 g / L or more in water at 20°C include acetic acid.

[0033] The pre-filter etching solution composition of this disclosure is preferably free of hydrogen peroxide from the viewpoint of reducing etching unevenness. Here, "free of hydrogen peroxide" includes, in one or more embodiments, free of hydrogen peroxide, substantially free of hydrogen peroxide, or free of hydrogen peroxide in an amount that affects the etching result. The amount of hydrogen peroxide blended in the pre-filter etching solution composition of this disclosure is not particularly limited, but is preferably less than 1% by mass, more preferably 0.5% by mass or less, even more preferably 0.1% by mass or less, even more preferably 0.01% by mass or less, and even more preferably 0% by mass.

[0034] (viscosity) The viscosity of the pre-filtration etching solution composition of this disclosure at 60°C is preferably 30 mPa·s or less, more preferably 25 mPa·s or less, and even more preferably 20 mPa·s or less, from the viewpoint of filtration rate. In this disclosure, the viscosity of the etching solution composition can be measured using a general-purpose viscometer such as a B-type viscometer or an Ubbelohde viscometer, and specifically, it can be measured by the method described in the examples.

[0035] (pH) The pH of the pre-filtered etching solution composition of this disclosure is preferably 1 or less, more preferably 0 or less, even more preferably less than 0, and even more preferably around -1, from the viewpoint of storage stability and reduction of etching unevenness. The pH of the pre-filtered etching solution composition of this disclosure can be -5 or higher, or -3 or higher. In this disclosure, the pH of the etching solution composition is the value at 25°C and can be measured using a pH meter, specifically by the method described in the examples.

[0036] [Method for producing pre-filtered etching solution composition] The pre-filtered etching solution composition of the present disclosure is obtained in one or more embodiments by blending phosphoric acid, nitric acid, an organic acid having a solubility in water at 20°C of 900 g / L or less, an etching inhibitor, water, and optionally the above-mentioned optional components in a known manner.

[0037] [Etching solution composition after filtration] The components and their proportions contained in the filtered etching solution composition obtained in the filtration step of this disclosure (hereinafter also referred to as the "filtered etching solution composition of this disclosure") can be the same as those in the pre-filtration etching solution composition of this disclosure described above in one or more embodiments. In this disclosure, "the amount of each component in the etchant composition after filtration" means, in one or more embodiments, the amount of each component in the etchant composition used in the etching process, i.e., at the time of use when the etching process begins (at the time of use). The amounts of each component in the filtered etching solution composition of this disclosure can be considered as the content of each component in the filtered etching solution composition of this disclosure in one or more embodiments. However, the amounts of each component and the content may differ when neutralization is involved.

[0038] In one or more embodiments, the viscosity and pH of the filtered etching solution composition of this disclosure may be the same as the pH of the pre-filtered etching solution composition described above.

[0039] Embodiments of the post-filtered etching solution composition of this disclosure may be a so-called one-component type, where all components are pre-mixed and supplied to the market, or a so-called two-component type, where the components are mixed at the time of use.

[0040] The filtered etching solution composition of this disclosure may be stored and supplied in a concentrated state, to the extent that its storage stability is not impaired. This is preferable in that it can reduce manufacturing and transportation costs. This concentrated solution can then be used in the etching process after being appropriately diluted with water or an aqueous acid solution as needed. The dilution ratio can be, for example, 3 to 100 times.

[0041] [Etched film] The film to be etched using the filtered etching solution composition of this disclosure is, in one or more embodiments, a metal film containing at least one metal. Here, the metal film is not particularly limited as long as the effects of this disclosure are achieved, but examples include a metal film containing at least one metal selected from tungsten, tantalum, zirconium, hafnium, molybdenum, niobium, ruthenium, osmium, rhenium, rhodium, copper, nickel, cobalt, titanium, titanium nitride, alumina, aluminum, and iridium. In one or more embodiments, the metal film does not contain silver. The filtered etching solution compositions of this disclosure are preferably used in one or more embodiments to etch a metal film (but not silver) containing at least one metal selected from tungsten, tantalum, zirconium, molybdenum, niobium, and nickel, and are suitably used in one or more embodiments to etch a tungsten film, a molybdenum film, or a nickel film. That is, the film to be etched is, in one or more embodiments, a tungsten film, a molybdenum film, or a nickel film.

[0042] [Method for producing etching solution composition] This disclosure relates to a method for producing an etching solution composition (hereinafter also referred to as "the etching solution production method of this disclosure"), which includes a step of filtering an etching solution composition for etching a metal film formed on a substrate at a temperature of 30°C or higher (hereinafter also referred to as "filtration step"), wherein the etching solution composition contains phosphoric acid, nitric acid, an organic acid having a solubility in water at 20°C of 900 g / L or less, an etching inhibitor, and water, and the amount of the organic acid in the etching solution composition is 10% by mass or more and 70% by mass or less. The etching solution production method of this disclosure can improve the productivity of etching solution compositions. In one or more embodiments, the filtration method and filtration conditions in the filtration step of the etching solution manufacturing method of this disclosure may be the same as those in the filtration step of the filtration method of this disclosure described above. In one or more embodiments, the etching solution composition filtered in the filtration step of the etching solution manufacturing method of this disclosure is the pre-filtered etching solution composition of this disclosure described above.

[0043] In one or more embodiments, the etching solution manufacturing method of the present disclosure may include a step of compounding at least phosphoric acid, nitric acid, an organic acid having a solubility in water at 20°C of 900 g / L or less, an etching inhibitor, and water before the filtration step. In the present disclosure, "compounding at least phosphoric acid, nitric acid, an organic acid having a solubility in water at 20°C of 900 g / L or less, an etching inhibitor, and water" means, in one or more embodiments, simultaneously or sequentially mixing phosphoric acid, nitric acid, an organic acid having a solubility in water at 20°C of 900 g / L or less, an etching inhibitor, water, and optionally the above-mentioned optional components. The order of mixing is not particularly limited. The compounding can be carried out using, for example, a mixer such as a propeller-type stirrer, liquid circulation stirring with a pump, a homomixer, a homogenizer, an ultrasonic disperser, and a wet ball mill. In the etching solution manufacturing method of this disclosure, the preferred blending amounts of each component can be the same as the preferred blending amounts of each component in the pre-filtered etching solution composition of this disclosure described above.

[0044] [Etching method] This disclosure relates to an etching method (hereinafter also referred to as "the etching method of this disclosure") which, in one embodiment, includes a step of etching a metal film formed on a substrate using an etching solution composition obtained by filtering at a temperature of 30°C or higher (hereinafter also referred to as "the etching step of this disclosure"), wherein the etching solution composition contains phosphoric acid, nitric acid, an organic acid having a solubility in water at 20°C of 900 g / L or less, an etching inhibitor, and water, and the amount of the organic acid in the etching solution composition is 10% by mass or more and 70% by mass or less. In one or more embodiments, the etching solution composition used in the etching step of this disclosure is the filtered etching solution composition of this disclosure described above. According to the etching method of this disclosure, the productivity of semiconductor substrates can be improved by using an etching solution composition that can improve the filtration rate while suppressing changes in the concentration of components contained in the etching solution composition even when filtered at a temperature of 30°C or higher. In one or more embodiments, the etching method of this disclosure may include a step of circulating and filtering the etching solution composition. In one or more embodiments, the circulating and filtering step may include a step of performing the filtration method of this disclosure described above on the circulating etching solution composition.

[0045] In the etching process of this disclosure, examples of etching methods include immersion etching and single-wafer etching.

[0046] In one or more embodiments, when the film to be etched is a tungsten film, the temperature of the etching solution composition in the etching process of the present disclosure (etching temperature) is preferably 0°C or higher, more preferably 50°C or higher, even more preferably 70°C or higher, and preferably 150°C or lower, more preferably 130°C or lower, and even more preferably 110°C or lower, from the viewpoint of reducing etching unevenness. Similarly, in one or more embodiments, when the film to be etched is a tungsten film, the etching temperature is preferably 0°C or higher and 150°C or lower, more preferably 50°C or higher and 130°C or lower, and even more preferably 70°C or higher and 110°C or lower. In one or more embodiments, when the film to be etched is a molybdenum film, the temperature of the etching solution composition in the etching process of the present disclosure (etching temperature) is preferably 0°C or higher, more preferably 15°C or higher, even more preferably 25°C or higher, and preferably 80°C or lower, more preferably 65°C or lower, and even more preferably 50°C or lower, from the viewpoint of reducing etching unevenness. From a similar viewpoint, in one or more embodiments, when the film to be etched is a molybdenum film, the etching temperature is preferably 0°C or higher and 80°C or lower, more preferably 15°C or higher and 65°C or lower, and even more preferably 25°C or higher and 50°C or lower. In one or more embodiments, when the film to be etched is a nickel film, the temperature of the etching solution composition in the etching process of the present disclosure (etching temperature) is preferably 0°C or higher, more preferably 15°C or higher, even more preferably 30°C or higher, and preferably 80°C or lower, more preferably 65°C or lower, and even more preferably 50°C or lower, from the viewpoint of reducing etching unevenness. Similarly, in one or more embodiments, when the film to be etched is a nickel film, the etching temperature is preferably 0°C or higher and 80°C or lower, more preferably 15°C or higher and 65°C or lower, and even more preferably 30°C or higher and 50°C or lower.

[0047] In the etching process of this disclosure, the etching time can be set, for example, to 1 minute or more and 180 minutes or less.

[0048] In one or more embodiments, when the film to be etched is a tungsten film, the etching rate in the etching process of this disclosure is preferably 0.0001 mg / min or more, more preferably 0.0005 mg / min or more, and even more preferably 0.001 mg / min or more, from the viewpoint of improving productivity, and preferably 10 mg / min or less, more preferably 1 mg / min or less, and even more preferably 0.1 mg / min or less, from the viewpoint of reducing etching unevenness. In one or more embodiments, when the film to be etched is a molybdenum film, the etching rate in the etching process of this disclosure is preferably 0.01 mg / min or more, more preferably 0.03 mg / min or more, and even more preferably 0.05 mg / min or more, from the viewpoint of improving productivity, and preferably 10 mg / min or less, more preferably 3 mg / min or less, and even more preferably 1 mg / min or less, from the viewpoint of reducing etching unevenness. In one or more embodiments, when the film to be etched is a nickel film, the etching rate in the etching process of this disclosure is preferably 0.001 mg / min or more, more preferably 0.005 mg / min or more, and even more preferably 0.01 mg / min or more, from the viewpoint of improving productivity, and preferably 10 mg / min or less, more preferably 1 mg / min or less, and even more preferably 0.5 mg / min or less, from the viewpoint of reducing etching unevenness.

[0049] The etching solution compositions and etching methods of the present disclosure can be used in one or more embodiments to etch metals in the manufacturing process of electronic devices, particularly semiconductor wafers. The etching solution composition and etching method of this disclosure can be suitably used in one or more embodiments to produce at least one substrate selected from semiconductor wafers, liquid crystal display substrates, plasma display substrates, FED (Field Emission Display) substrates, optical disc substrates, magnetic disk substrates, magneto-optical disk substrates, photomask substrates, ceramic substrates, and solar cell substrates. That is, in one embodiment, this disclosure relates to a substrate processing method (hereinafter also referred to as "the substrate processing method of this disclosure") which includes a step of etching a metal film formed on a substrate using the etching solution composition and etching method of this disclosure, wherein the substrate is at least one substrate selected from semiconductor wafers, liquid crystal display substrates, plasma display substrates, FED (Field Emission Display) substrates, optical disc substrates, magnetic disk substrates, magneto-optical disk substrates, photomask substrates, ceramic substrates, and solar cell substrates. According to the substrate processing method of this disclosure, the productivity and yield of semiconductor substrates can be improved by using an etching solution filtered by the filtration method of this disclosure. The etching solution compositions and etching methods of the present disclosure can be used in one or more embodiments to etch electrodes in the manufacturing process of electronic devices, particularly semiconductor memories such as non-volatile memories including NAND flash memory. The etching solution composition and etching method of this disclosure can be suitably used in one or more embodiments to produce patterns having a three-dimensional structure. This makes it possible to obtain advanced devices such as high-capacity memory. The etching solution composition and etching method of this disclosure can be used, for example, in etching methods such as those disclosed in Japanese Patent Application Publication No. 2020-145412. [Examples]

[0050] 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.

[0051] 1. Preparation of etching solution (Examples 1-6, Comparative Examples 1-2) Etching solutions (pH: 0 to -2) for Examples 1 to 6 and Comparative Examples 1 to 2 were obtained by combining phosphoric acid, nitric acid, the organic acids shown in Table 1, the etching inhibitors shown in Table 1, and water. Table 1 shows the proportions (mass %) and effective content of each component in the prepared etching solution. Note that the proportion of water in Table 1 includes the amount of water contained in acidic aqueous solutions, etc.

[0052] The following components were used to prepare the etching solution. Phosphoric acid [manufactured by Phosphorus Chemical Industry Co., Ltd., concentration 85%] Nitric acid [Fujifilm Wako Pure Chemical Industries, Ltd., 70% concentration] Acetic acid [Fujifilm Wako Pure Chemical Industries, Ltd., 100% concentration, solubility in water at 20°C: 1000 g / L] Methoxyacetic acid [Fujifilm Wako Pure Chemical Industries, Ltd., concentration 95%, solubility in water at 20°C: 485 g / L] Polyethyleneimine [Number average molecular weight 1,800, "Epomin SP-018" manufactured by Nippon Shokubai Co., Ltd.] Water [Ultrapure water produced using a continuous pure water production system (PureConti PC-2000VRL model) and subsystem (MacAce KC-05H model) manufactured by Kurita Water Industries Ltd.]

[0053] 2. Method for measuring parameters [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.

[0054] [Viscosity of etching solution] The viscosity of the etching solution was measured using the following viscometer under the following conditions. Device name: TVB-10 viscometer (with constant temperature bath) manufactured by Toki Sangyo Co., Ltd. Rotor: Spindle No. M1, Cord No. 20 Viscosity value measured at rotation speed: 100 rpm, after 60 seconds. Measurement temperature: 25℃, 60℃

[0055] [Percentage decrease in organic acid concentration] Prepare an aqueous solution of organic acid (with the remainder being water) containing the same concentration of organic acid as that found in each prepared etching solution composition. Then, store it in an open system at 60°C for 30 minutes, and measure the weight of the aqueous solution before and after storage. Then, the rate of decrease in the concentration of organic acids is calculated using the following formula. Organic acid concentration reduction rate (%) = 100 - (weight of organic acid solution after storage at 60°C for 30 minutes) / initial weight of organic acid solution

[0056] 3. Evaluation of etching solution [Evaluation of filtration rate (productivity)] Each prepared etching solution composition was filtered using the filtration system shown in Figure 1 under the following conditions, and the filtration rate (productivity) was evaluated based on the following evaluation criteria. Here, the filtration system shown in Figure 1 comprises a tank 1 for storing the etching solution composition, a pump 2 for transporting the etching solution composition, a filter 3 for filtering the etching solution composition, an outlet valve 4 for controlling the flow rate of the etching solution composition discharged from the outlet 5, and piping P1 connecting the tank 1, pump 2, filter 3, outlet valve 4, and outlet 5. Furthermore, it includes a circulation path P2 that branches off from the piping P1 between the filter 3 and the outlet valve 4 and connects to the upstream side of the pump 2. The filling system shown in Figure 1 further includes a circulation valve 7 for controlling the flow rate of the etching solution composition circulating through the circulation path P2. First, the prepared etching solution composition is placed in tank 1. Then, the etching solution composition in tank 1 is pumped by pump 2, filtered by filter 3, and the filtered etching solution composition is filled into container 6. <Conditions and Equipment> Pump 2: Diaphragm pump DP-10BPT (manufactured by Yamada Corporation) Piping P1, P2: Corrugated flexible hose 15A (manufactured by Fluorochemical Co., Ltd.) Filter 3: Fluoroguard FP CWEX010V1 (Entegris, 20nm) Container 6: 20L container (polyethylene can (color: gray), manufactured by Kodama Resin Industry Co., Ltd.) <Condition> Filtration temperature: Listed in Table 1 Filtration time: See Table 1 Filtration pressure: 0.3 MPa Filtration flow rate: 0.5~20kg / (m 2 ·min) Scale: Etching solution composition 300 kg <Evaluation Criteria> ○: Production can be carried out without any problems regarding productivity or changes in the components of the etching solution composition. ×: High viscosity and long filtration time present challenges to productivity. [Table 1]

[0057] As shown in Table 1, in Examples 1 to 6, which used an organic acid (methoxyacetic acid) with a solubility in water at 20°C of 900 g / L or less combined with an etching inhibitor, the rate of decrease in the concentration of the organic acid before and after filtration was smaller, and the viscosity was lower and the filtration time was shorter compared to Comparative Examples 1 to 2, which used an organic acid (acetic acid) with a solubility in water at 20°C of more than 900 g / L combined with an etching inhibitor. This indicates that even when filtered at temperatures above 30°C, the concentration change of the components contained in the etching solution composition was suppressed while the filtration rate was improved. [Industrial applicability]

[0058] The etching solution composition obtained using the filtration method of this disclosure is useful for etching metal films on semiconductor wafers, substrates for liquid crystal displays, substrates for plasma displays, substrates for FEDs (Field Emission Displays), substrates for optical discs, substrates for magnetic discs, substrates for magneto-optical discs, substrates for photomasks, ceramic substrates, and substrates for solar cells. [Explanation of symbols]

[0059] 1...Tank, 2...Pump, 3...Filter, 4...Outlet valve, 5...Outlet, 6...Container, 7...Circulation valve, P1...Piping, P2...Piping (Circulation route)

Claims

1. The process includes filtering an etching solution composition for etching a film to be etched, which contains titanium nitride, alumina, or at least one metal, formed on a substrate, at a temperature of 30°C or higher. The etching solution composition contains phosphoric acid, nitric acid, an organic acid with a solubility in water at 20°C of 900 g / L or less, an etching inhibitor, and water. The amount of the organic acid in the etching solution composition is 10% by mass or more and 70% by mass or less. A method for filtering an etching solution composition, wherein the pH of the etching solution composition is 1 or less.

2. The filtration method according to claim 1, wherein the metal is a metal film containing at least one metal selected from tungsten, tantalum, zirconium, hafnium, molybdenum, niobium, ruthenium, osmium, rhenium, rhodium, copper, nickel, cobalt, titanium, aluminum, and iridium.

3. The filtration method according to claim 1 or 2, wherein the organic acid is at least one selected from alkoxycarboxylic acids, hydroxy acids, aliphatic polycarboxylic acids, and alkoxyacetic acid esters.

4. The filtration method according to claim 1 or 2, wherein the etching inhibitor is at least one selected from polyalkyleneimines and polyalkylene polyamines.

5. The filtration method according to claim 1 or 2, wherein the amount of the organic acid in the etching solution composition is 20% by mass or more.

6. The filtration method according to claim 1 or 2, wherein the amount of phosphoric acid in the etching solution composition is 1% by mass or more and 90% by mass.

7. The filtration method according to claim 1 or 2, wherein the amount of nitric acid in the etching solution composition is 0.5% by mass or more and 20% by mass or less.

8. The filtration method according to claim 1 or 2, wherein the viscosity of the etching solution composition at 60°C is 30 mPa·s or less.

9. The filtration method according to claim 1 or 2, wherein the amount of hydrogen peroxide in the etching solution composition is less than 1% by mass.

10. The process includes filtering an etching solution composition for etching a film to be etched, which contains titanium nitride, alumina, or at least one metal, formed on a substrate, at a temperature of 30°C or higher. The etching solution composition contains phosphoric acid, nitric acid, an organic acid with a solubility in water at 20°C of 900 g / L or less, an etching inhibitor, and water. The amount of the organic acid in the etching solution composition is 10% by mass or more and 70% by mass or less. A method for producing an etching solution composition, wherein the pH of the etching solution composition is 1 or less.

11. The process includes etching a film to be etched, which is formed on a substrate and contains titanium nitride, alumina, or at least one metal, using an etching solution composition obtained by filtering at a temperature of 30°C or higher. The etching solution composition contains phosphoric acid, nitric acid, an organic acid with a solubility in water at 20°C of 900 g / L or less, an etching inhibitor, and water. The amount of the organic acid in the etching solution composition is 10% by mass or more and 70% by mass or less. An etching method wherein the pH of the etching solution composition is 1 or less.

12. A method for manufacturing a semiconductor wafer using the etching method of claim 11.

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