Microprocessing treatment agent and microprocessing treatment method

Abstract

Provided are a microprocessing treatment agent and a microprocessing treatment method that reduce or suppress foaming, impart excellent defoaming properties, and make it possible to satisfactorily perform selective microprocessing on a silicon oxide film even in a narrow region, and to improve throughput and yield. This microprocessing treatment agent is for microprocessing a workpiece having at least a silicon oxide film 2, the agent comprising: (a) hydrogen fluoride having a content in the range of 25 mass% or less with respect to the total mass of the microprocessing treatment agent; (b) at least one or more water-soluble polymers having a content in the range of 1×10-4 mass% to 1 mass% with respect to the total mass of the microprocessing treatment agent and having a mass average molecular weight in the range of 600 to 50,000; and (c) water. The water-soluble polymers include a structural unit having a primary amino group and / or a secondary amino group.

Description

Microprocessing agent and microprocessing method

[0001] The present invention relates to a micro-processing treatment agent and a micro-processing method used in micro-processing including etching and cleaning processes in the manufacture of semiconductor devices, liquid crystal display devices, microelectromechanical systems (MEMS) devices, etc., and more particularly to a micro-processing treatment agent and a micro-processing method used in the micro-processing of silicon oxide films.

[0002] Wet etching is used in the manufacturing process of semiconductor devices, for example, in 3D-NAND nonvolatile memory. Conventional NAND nonvolatile memory has been miniaturized using a planar type, but this has led to a decrease in electrical reliability and a limit to miniaturization. Therefore, 3D-NAND nonvolatile memory has been developed, which uses a trench type in which memory cells are stacked vertically, thereby increasing capacity without reducing the size of the memory cells.

[0003] The manufacturing process of this 3D-NAND nonvolatile memory includes, for example, a wet etching process in which a silicon oxide film and a polysilicon film are sequentially stacked on a silicon substrate, and the silicon oxide film is selectively removed as a sacrificial layer. This wet etching process utilizes the difference in etching speed between the silicon oxide film and the polysilicon film, and examples of the etching solution used include an etching solution made of hydrofluoric acid and an etchant containing dilute hydrofluoric acid and a surfactant (Patent Document 1).

[0004] However, with the miniaturization of semiconductor devices, there is a demand for controlling wet etching processes on the nanometer scale. In particular, in stacked structures containing silicon oxide films, selective removal of the silicon oxide film is sometimes required to form elongated recesses with narrow and deep openings. However, it is difficult for an etchant containing hydrofluoric acid to efficiently penetrate into such narrow recesses (i.e., into the narrow area). This poses a problem: the etching rate of silicon oxide films in narrow recesses is lower than that in recesses with conventional openings. This problem is also pointed out in Non-Patent Document 1. According to Non-Patent Document 1, under certain conditions, the etching rate decreases as the etching area narrows. Furthermore, this decrease in etching rate is attributed to the effect of an electric double layer formed near the solid-liquid interface. Therefore, a decrease in the etching rate in narrow recesses leads to reduced throughput due to increased etching time and a decrease in yield due to the inability to finely process the stacked structure into the desired structure.

[0005] Furthermore, Patent Document 1 claims that an etchant containing dilute hydrofluoric acid and a surfactant can improve the etching rate of silicon oxide films in recesses in narrow spaces, but because it contains a surfactant, bubbles are generated during use, which results in the etchant not coming into uniform contact with the silicon oxide film, resulting in uneven etching of the silicon oxide film and the resulting problem of uneven etching.

[0006] Japanese Patent Application Laid-Open No. 2021-48369

[0007] Atsushi Okuyama, et al., Solid State Phenomena, Vol. 219, pp 115-118, 2014

[0008] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a fine processing treatment agent and a fine processing method that reduce or inhibit foaming, have excellent defoaming properties, enable selective fine processing of silicon oxide films to be performed well even in narrow spaces, and enable improvements in throughput and yield.

[0009] In order to solve the above-mentioned problems, the present invention provides a fine-processing treatment agent for selectively fine-processing a silicon oxide film on a workpiece having at least the silicon oxide film, the fine-processing treatment agent comprising: (a) hydrogen fluoride in a content of 25 mass % or less relative to the total mass of the fine-processing treatment agent; and (b) hydrogen fluoride in a content of 1×10 relative to the total mass of the fine-processing treatment agent. －４ The composition is characterized by comprising: (a) at least one water-soluble polymer, the water-soluble polymer having a mass average molecular weight of 600 to 50,000, the mass average molecular weight of which is in the range of 1% by mass or more and 1% by mass or less; and (c) water, wherein the water-soluble polymer contains a structural unit having a primary amino group and / or a secondary amino group.

[0010] According to the above-mentioned configuration, by setting the hydrogen fluoride content to 25 mass % or less, it is possible to suppress an excessively high etching rate when etching a silicon oxide film. As a result, it is possible to prevent other films, such as a polysilicon film, from being etched together with the silicon oxide film, and it is possible to maintain good selective etching performance for the silicon oxide film. In addition, a water-soluble polymer containing a structural unit having a primary amino group and / or a secondary amino group and having a mass average molecular weight in the range of 600 to 50,000 is used in an amount of 1×10 －４By including the additive in a range of 1% by mass or more and 1% by mass or less, for example, in a stacked structure including a silicon oxide film, even when selectively removing the silicon oxide film to form a narrow, deep recess, the etching rate of the silicon oxide film in such a narrow area can be maintained. As a result, this configuration suppresses an increase in the etching time of the silicon oxide film and improves throughput. Furthermore, since the additive reduces or suppresses the generation of bubbles and has excellent defoaming properties, it facilitates the penetration of the micro-processing agent into narrow areas compared to conventional micro-processing agents. Therefore, uneven micro-processing, such as etching irregularities caused by the generation of bubbles, can be prevented, and micro-processing can be performed well in narrow areas of a stacked structure including a silicon oxide film, thereby improving yield.

[0011] According to the above-mentioned configuration, (d) the content of the fine processing treatment agent relative to the total mass is 1×10 －４ % by mass or more and 1% by mass or less, and Cl － ,Br － , C.H. ３ COO － , HSO ４ － , S.O. ４ ２－ , NO ３ － , H ２ P.O. ４ － , H.P.O. ４ ２－ and P.O. ４ ３－ The compound having a counter ion is preferably contained in an amount of 1×10 based on the total mass of the fine processing treatment agent. －４ By including the compound in the range of 0.01 wt % to 1 wt %, it is possible to suppress foaming while maintaining a good etching rate for silicon oxide films in narrow spaces, which results in a further improvement in throughput and yield even in selective micro-processing of silicon oxide films in narrow spaces, compared to conventional micro-processing agents.

[0012] In the above-mentioned structure, the structural unit is preferably represented by any one of the following chemical formulas (1) to (4).

[0013]

[0014] In the above-mentioned configuration, the compound having a counter ion is preferably an ammonium salt, a potassium salt, or a carboxylic acid.

[0015] Furthermore, in the above-mentioned configuration, it is preferable that the ammonium salt is at least one selected from the group consisting of ammonium chloride, ammonium bromide, ammonium acetate, ammonium sulfate, ammonium nitrate, diammonium hydrogen phosphate, and triammonium phosphate.

[0016] In the above-mentioned composition, the potassium salt is preferably potassium acetate.

[0017] In the above-mentioned composition, the carboxylic acid is preferably acetic acid.

[0018] Furthermore, the fine processing treatment agent having the above-described configuration is preferably a surfactant-free treatment agent. By using a surfactant-free fine processing treatment agent, the generation of foaming during use can be further prevented. This reduces uneven contact of the fine processing treatment agent with the silicon oxide film due to the generation of foaming, and further prevents the occurrence of uneven etching.

[0019] In order to solve the above-mentioned problems, the micro-processing method of the present invention is characterized in that, using the micro-processing treatment agent having the above-mentioned configuration, the silicon oxide film on a workpiece having at least the silicon oxide film is selectively micro-processed.

[0020] According to the above-described configuration, the micro-processing agent can effectively perform selective micro-processing of silicon oxide films while reducing or suppressing the generation of bubbles. Therefore, with the above-described configuration, even when selectively micro-processing silicon oxide films in narrow spaces, such as in semiconductor manufacturing processes for 3D-NAND nonvolatile memories, the etching rate for silicon oxide films can be maintained at a good level. As a result, increases in the etching time for silicon oxide films can be suppressed, improving throughput. Furthermore, since the agent reduces or suppresses the generation of bubbles and has excellent defoaming properties, it facilitates penetration of the agent into narrow spaces compared to conventional micro-processing agents. Therefore, uneven micro-processing, such as etching irregularities caused by the generation of bubbles, can be prevented, and micro-processing of silicon oxide films in narrow spaces can be effectively performed, thereby improving yield.

[0021] The present invention achieves the following effects by the means described above: That is, the present invention can provide a fine processing agent and a fine processing method that reduce or inhibit foaming, have excellent defoaming properties, enable selective fine processing of silicon oxide films to be performed well even in narrow spaces, and enable improvements in throughput and yield.

[0022] Fig. 1(a) is a cross-sectional view showing a blanket-like silicon oxide film formed on a substrate, and Fig. 1(b) is a cross-sectional view showing a silicon oxide film subjected to micro-processing using the micro-processing treatment agent of the present embodiment. Fig. 2(a) is a cross-sectional view showing a silicon oxide film and a polysilicon film sequentially stacked on a substrate, and Fig. 2(b) is a cross-sectional view showing a narrow area of ​​the silicon oxide film subjected to micro-processing using the micro-processing treatment agent of the present embodiment. Fig. 2(b) is a plan view showing a schematic view of bubbles of etching solution adhering to the inner wall of a polystyrene bottle.

[0023] (Fine-processing treatment agent) A fine-processing treatment agent according to one embodiment of the present invention will be described below. The fine-processing treatment agent according to this embodiment contains at least (a) hydrogen fluoride, (b) at least one water-soluble polymer, and (c) water. Furthermore, it is preferable that the fine-processing treatment agent of this embodiment further contains a compound having a counter ion.

[0024] The micro-processing agent of this embodiment is suitable for use in selectively micro-processing a silicon oxide film on a workpiece having at least the silicon oxide film. In this specification, "micro-processing" includes an etching process for micro-processing the surface or interior of the workpiece, and a cleaning process for the surface of the workpiece. When etching the workpiece, the micro-processing agent of this embodiment functions as an etching solution. The workpiece is not particularly limited, but examples include a laminate in which a silicon oxide film and other films such as a polysilicon film are sequentially stacked on a substrate. Furthermore, when cleaning the surface of the workpiece, the micro-processing agent of this embodiment functions as a cleaning solution.

[0025] The content of hydrogen fluoride, which is the component (a), is within the range of 25% by mass or less, preferably 0.1% by mass or more to 10% by mass or more, more preferably 1% by mass or more to 5% by mass or less, based on the total mass of the micro-processing treatment agent.By making the content of hydrogen fluoride 25% by mass or less, the etching rate for silicon oxide film becomes too high, and for example, the selective etching performance for other films such as polysilicon film is reduced, and the controllability of micro-processing is prevented from being reduced.In addition, the content of hydrogen fluoride is, for example, 0.1, 0.5, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, 11.0, 12.0, 13.0, 14.0, 15.0, 20.0, 25.0% by mass based on the total mass of the micro-processing treatment agent, and may also be within a range between any two of the values ​​exemplified here.

[0026] The water-soluble polymer (b) contains at least a structural unit having a primary amino group and / or a secondary amino group. Examples of the primary amino group include -NH ２ Examples of the secondary amino group include an —NH group. Of these amino groups, a primary amino group is preferred in this embodiment, and an —NH ２ The group is more preferred.

[0027] Examples of structural units having a primary amino group and / or a secondary amino group include those represented by any of the following chemical formulas (1) to (4).

[0028]

[0029] Specific examples of the water-soluble polymer include cationic water-soluble polymers and amphoteric water-soluble polymers. Examples of the cationic water-soluble polymer include polyallylamine (chemical formula (5) below), partially carbamoylated polyallylamine (chemical formula (6) below), and allylamine amide sulfate polymer (chemical formula (7) below).

[0030]

[0031] Examples of amphoteric water-soluble polymers include allylamine-sodium allylsulfonate copolymer (chemical formula (8) below) and allylamine-maleic acid copolymer (chemical formula (9) below).

[0032]

[0033] Water-soluble polymers can be obtained, for example, by polymerizing a monomer component containing at least a monomer having a primary amino group and / or a secondary amino group. Examples of such monomers include allylamine, carbamoylated allylamine, carboxymethylated allylamine, and allylamine amide sulfate. The monomer component may also contain other monomers, in which case the water-soluble polymer can be obtained as a copolymer of the monomer and the other monomer. Examples of such other monomers include sodium allylsulfonate and maleic acid. Furthermore, water-soluble polymers having structural units containing primary amino groups and / or secondary amino groups can also be obtained by polymerizing ethyleneamine with the carboxyl groups of water-soluble (meth)acrylic polymers. The term "water-soluble (meth)acrylic polymer" refers to both water-soluble acrylic polymers and water-soluble methacrylic polymers.

[0034] The mass average molecular weight of the water-soluble polymer is in the range of 600 to 50,000, preferably 1,500 to 50,000. When the mass average molecular weight of the water-soluble polymer is 600 or more, it is possible to maintain a good selectivity ratio of the etching rate of a silicon oxide film relative to a polysilicon film or the like, and to prevent a decrease in the controllability of microfabrication. On the other hand, when the mass average molecular weight of the water-soluble polymer is 50,000 or less, it is possible to suppress the microfabrication of films other than a silicon oxide film, such as a polysilicon film, and to prevent a decrease in the controllability of microfabrication. The weight average molecular weight of the water-soluble polymer may be, for example, 600, 1,000, 1,500, 2,000, 2,500, 3,000, 3,500, 4,000, 4,500, 5,000, 5,500, 6,000, 6,500, 7,000, 7,500, 8,000, 8,500, 9,000, 9,500, 10,000, 15,000, 20,000, 25,000, 30,000, 35,000, 40,000, or 50,000, or may be within a range between any two of the values ​​exemplified here. The weight average molecular weight (Mw) of the water-soluble polymer can be measured, for example, by gel permeation chromatography (GPC), osmometry, viscosity analysis, light scattering, or sedimentation velocity analysis.

[0035] The content of the water-soluble polymer is 1×10 relative to the total mass of the fine processing treatment agent. －４ % by mass or more and 1% by mass or less, and preferably 1×10 －３ % by mass or more and 1% by mass or less, and more preferably 1×10 －3 Mass% or more, 1×10 －１ The content of the water-soluble polymer is in the range of 1×10 －４By making the content of the water-soluble polymer 1% by mass or more, it is possible to maintain a good selectivity ratio of the etching rate of silicon oxide film to polysilicon film, etc., and to prevent a decrease in the controllability of microfabrication. On the other hand, by making the content of the water-soluble polymer 1% by mass or less, it is possible to suppress the microfabrication of films other than silicon oxide film, such as polysilicon film, and to prevent a decrease in the controllability of microfabrication. The content of the water-soluble polymer is, for example, 1 x 10 with respect to the total mass of the microfabrication treatment agent. －４ , 1×10 －３ , 1×10 －２ , 2 × 10 －２ , 3 x 10 －２ , 4 x 10 －２ , 5 x 10 －２ , 6 x 10 －２ , 7 x 10 －２ , 8 x 10 －２ , 9 x 10 －２ , 1×10 －１ , 2 × 10 －１ , 3 x 10 －１ , 4 x 10 －１ , 5 x 10 －１ , 6 x 10 －１ , 7 x 10 －１ , 8 x 10 －１ , 9 x 10 －１ , 1% by mass, and may be in a range between any two of the values ​​exemplified herein.

[0036] The water-soluble polymer may be a mixture of two or more different types of polymers. The different types of polymers mentioned here include polymers having different molecular structures as well as polymers having the same molecular structure but different mass-average molecular weights.

[0037] The compound having a counter ion, which is the component (d), is Cl － ,Br － , C.H. ３ COO － , HSO ４ － , S.O. ４ ２－ , NO ３ － , H ２ P.O. ４ －, H.P.O. ４ ２－ and P.O. ４ ３－ The compound has at least one ion selected from the group consisting of: (I) a compound having at least one ion selected from the group consisting of: (II) a compound having at least one counter ion selected from the group consisting of: (II ...

[0038] The content of the compound having a counter ion is 1×10 relative to the total mass of the fine processing treatment agent. －４ % by mass or more and 1% by mass or less, and preferably 1×10 －３ Mass% or more, 5 x 10 －1 The content of the compound having a counter ion is in the range of 1×10 mass % or less. －４ By making the content of the compound having counter ions 1% by mass or more, the etching rate of the silicon oxide film in the recessed portion in a narrow place can be further improved. On the other hand, by making the content of the compound having counter ions 1% by mass or less, the selectivity of the etching rate of the silicon oxide film relative to the polysilicon film or the like can be maintained well, and the controllability of the microfabrication can be prevented from being deteriorated. The content of the compound having counter ions is, for example, 1×10 －４ , 1×10 －３ , 1×10 －２ , 2 × 10 －２ , 3 x 10 －２ , 4 x 10 －２ , 5 x 10 －２ , 6 x 10 －２ , 7 x 10 －２ , 8 x 10 －２ , 9 x 10 －２ , 1×10 －１ , 2 × 10 －１ , 3 x 10－１ , 4 x 10 －１ , 5 x 10 －１ , 6 x 10 －１ , 7 x 10 －１ , 8 x 10 －１ , 9 x 10 －１ , 1% by mass, and may be in a range between any two of the values ​​exemplified herein.

[0039] The water as the component (c) contained in the fine processing agent of the present embodiment is not particularly limited, but is preferably pure water, ultrapure water, or the like.

[0040] The water content is preferably in the range of 73% by mass or more, more preferably 83% by mass or more, and particularly preferably 93% by mass or more, based on the total mass of the fine processing agent.

[0041] The fine processing treatment agent of this embodiment is preferably a surfactant-free treatment agent. The absence of a surfactant in the fine processing treatment agent further prevents foaming during use. This reduces uneven contact of the fine processing treatment agent with the silicon oxide film due to foaming, further preventing uneven etching. Examples of surfactants that are not preferably contained in the fine processing treatment agent of this embodiment include monoalkyl sulfates.

[0042] The fine processing treatment agent of this embodiment may be composed only of hydrogen fluoride, a water-soluble polymer, and water, or may be composed only of these components to which a compound having a counter ion has been added. Furthermore, the fine processing treatment agent of this embodiment may further contain other additives within a range that does not impair the effects of the present invention. Examples of other additives include hydrogen peroxide and a chelating agent. The content of the other additives can be appropriately set as needed.

[0043] The defoaming time of the micro-processing treatment agent of this embodiment is preferably less than 300 seconds, more preferably less than 60 seconds. This allows the micro-processing treatment agent to efficiently penetrate into narrow spaces, even if foaming occurs when the micro-processing treatment agent is supplied to the workpiece for micro-processing. Furthermore, this prevents the micro-processing treatment agent from coming into uneven contact with the silicon oxide film due to foaming, resulting in uneven micro-processing, such as etching. The defoaming time can be measured by the method described in the Examples.

[0044] The method for producing the fine-processing treatment agent according to the present embodiment is not particularly limited, and various methods can be adopted. For example, the fine-processing treatment agent according to the present embodiment can be produced by adding a water-soluble polymer, an optional compound having a counter ion, and other additives to hydrofluoric acid in any order or simultaneously.

[0045] (Micro-processing method) Next, a micro-processing method using the micro-processing treatment agent of this embodiment will be described below. The micro-processing treatment agent of this embodiment is suitable for selectively micro-processing a silicon oxide film on a workpiece having at least a silicon oxide film with a thickness of, for example, 5 nm or 10 nm.

[0046] 1(a) and 1(b), the micro-processing method of the present embodiment is suitable for selectively micro-processing a silicon oxide film 2 formed in a blanket state on a substrate 1. Fig. 1(a) is a cross-sectional view showing the silicon oxide film 2 formed in a blanket state on the substrate 1, and Fig. 1(b) is a cross-sectional view showing the silicon oxide film 2 after micro-processing using the micro-processing agent of the present embodiment.

[0047] The fine processing agent of this embodiment is also suitable for selectively performing fine processing on a silicon oxide film in a stacked structure such as that shown in FIG. 2( a). The stacked structure shown in FIG. 2( a) has a structure in which a silicon oxide film 2 and a polysilicon film 3, which function as sacrificial layers, are sequentially stacked on a substrate 1. Furthermore, this stacked structure has multiple trenches 4 formed parallel to each other, and the surface of the substrate 1 is exposed where the trenches 4 are formed. When the fine processing agent is supplied onto the substrate 1, the agent penetrates into the stacked structure from the trenches 4 while reducing or minimizing the generation of bubbles, and contacts and removes the exposed areas of the silicon oxide film 2. Alternatively, even if bubbles are generated, the fine processing agent defoams over time, removing the silicon oxide film 2 in the narrow region R, as shown in FIG. 2( b). The narrow region R refers to the space between the substrate 1 and the polysilicon film 3. 2(a) is a schematic cross-sectional view showing a state in which a silicon oxide film 2 and a polysilicon film 3 are sequentially stacked on a substrate 1, and FIG. 2(b) is a schematic cross-sectional view showing a state in which fine processing has been performed on a narrow area of ​​the silicon oxide film 2 using the fine processing treatment agent of this embodiment.

[0048] The fine processing treatment agent of this embodiment is employed in various wet etching methods. Wet etching methods include batch and single-wafer methods, and the fine processing treatment agent of the present invention can be employed in either method. Batch wet etching methods are superior in terms of throughput because they can wet-etch a large number of wafers at once. However, in semiconductor manufacturing processes where semiconductor elements are becoming increasingly miniaturized, there is a problem of cross-contamination within the etching bath. Single-wafer wet etching methods are less susceptible to cross-contamination than batch wet etching methods, but are inferior to batch wet etching methods in terms of throughput.

[0049] Methods for contacting the fine processing treatment agent with the object to be treated include immersion and spraying. Of these contact methods, the immersion method is preferred because it can reduce or suppress changes in composition due to evaporation of the fine processing treatment agent during the process.

[0050] When the fine processing treatment agent is used as an etching solution, the etching temperature (i.e., the liquid temperature of the fine processing treatment agent) is preferably in the range of 50°C or less, more preferably in the range of 5°C or more to 50°C or less, even more preferably in the range of 15°C or more to 35°C or less, and particularly preferably in the range of 20°C or more to 30°C or less. By setting the etching temperature to 50°C or less, evaporation of the fine processing treatment agent can be suppressed, and changes in the composition of the fine processing treatment agent can be prevented. Furthermore, it is possible to prevent the evaporation of the fine processing treatment agent from making it difficult to control the etching rate. The etching temperature may be, for example, 5, 10, 15, 20, 25, 30, 35, or 50°C, or may be within a range between any two of the values ​​exemplified here.

[0051] Furthermore, when etching a blanket-shaped silicon oxide film 2 as shown in FIG. 1( a) using the micro-processing agent of this embodiment, the etching rate within the aforementioned etching temperature range is preferably 1 nm / min or more, more preferably 4 nm / min or more, and even more preferably 25 nm / min or more. By setting the etching rate for the blanket-shaped silicon oxide film 2 at 1 nm / min or more, selective micro-processing of the blanket-shaped silicon oxide film 2 can be further improved. As a result, the time required for micro-processing, such as wet etching, of the silicon oxide film 2 can be shortened, and a decrease in processing efficiency can be suppressed. Furthermore, by setting the etching rate at 270 nm / min or less, a decrease in controllability of the etching amount of the silicon oxide film 2 can be prevented, thereby maintaining practical applicability as an etching solution in semiconductor manufacturing processes. The etching rate for the blanket-shaped silicon oxide film 2 can be, for example, 1, 4, 25, 30, 35, 65, 110, 180, or 270 nm / min, or can be within a range between any two of the values ​​exemplified here.

[0052] Furthermore, when the fine processing agent of this embodiment is used to etch a narrow region of a silicon oxide film 2 in a stack formed on a substrate 1 as shown in FIG. 2( a), the etching rate within the aforementioned etching temperature range is preferably 1 nm / min or more, more preferably 4 nm / min or more, even more preferably 20 nm / min or more, and even more preferably 25 nm / min or more. By setting the etching rate for the silicon oxide film 2 in the narrow region at 1 nm / min or more, selective fine processing of the silicon oxide film 2 can be further improved. As a result, the time required for fine processing, such as wet etching of the silicon oxide film 2, can be shortened and a decrease in processing efficiency can be suppressed. Furthermore, by setting the etching rate at 270 nm / min or less, a decrease in controllability of the etching amount of the silicon oxide film 2 can be prevented, thereby maintaining practical applicability as an etching solution in semiconductor manufacturing processes. The etching rate for the silicon oxide film 2 in the narrow area may be, for example, 1, 4, 20, 25, 30, 50, 90, 150, 220, or 270 nm / min, or may be within a range between any two of the values ​​exemplified here.

[0053] Here, the silicon oxide film 2 is not particularly limited as long as it contains silicon (Si) and oxygen (O). Specific examples include a natural oxide film, a chemical oxide film, a silicon thermal oxide film, a non-doped silicate glass film, a phosphorus-doped silicate glass film, a boron-doped silicate glass film, a boron-phosphorus-doped silicate glass film, a TEOS (Tetraethyl Orthosilicate) film, a fluorine-containing silicon oxide film, a carbon-containing silicon oxide film, a nitrogen-containing silicon oxide film, an SOG (Spin on Glass) film, and an SOD (Spin on Dielectric) film.

[0054] Furthermore, the native oxide film in the silicon oxide film 2 refers to a silicon oxide film formed on silicon during exposure to the atmosphere at room temperature. The chemical oxide film refers to a film formed on silicon during cleaning with, for example, sulfuric acid and hydrogen peroxide. The thermal silicon oxide film refers to a film formed by supplying water vapor or oxygen gas at a high temperature of 800 to 1000°C. Non-doped silicate glass films, phosphorus-doped silicate glass films, boron-doped silicate glass films, boron-phosphorus-doped silicate glass films, TEOS films, fluorine-containing silicon oxide films, carbon-containing silicon oxide films, and nitrogen-containing silicon oxide films can be formed by supplying a source gas such as silane and depositing the silicon oxide film using a CVD (chemical vapor deposition) method. SOG films and SOD films can be formed by a coating method such as a spin coater.

[0055] Examples of the CVD method include film formation methods such as PECVD (Plasma Enhanced Chemical Vapor Deposition), ALD (Atomic Layer Deposition), MOCVD (Metal Organic Chemical Vapor Deposition), Cat-CVD (Catalytic Chemical Vapor Deposition), thermal CVD, and epitaxial CVD. Examples of the PVD method include film formation methods such as vacuum deposition, ion plating, ion beam deposition, and sputtering.

[0056] As described above, the micro-processing agent according to the present embodiment and the micro-processing method using the same can effectively perform selective micro-processing of a silicon oxide film in a narrow space in a laminate in which a silicon oxide film and other films are sequentially stacked on a substrate. Furthermore, the micro-processing agent according to the present embodiment and the micro-processing method using the same can suppress the generation of bubbles when micro-processing a silicon oxide film in a narrow space, or can quickly eliminate bubbles if they are generated. Therefore, it is possible to prevent the generation of bubbles from causing uneven micro-processing of the silicon oxide film. As a result, the micro-processing agent according to the present embodiment and the micro-processing method using the same are suitable for selective micro-processing of a silicon oxide film in the manufacturing process of semiconductor devices and the like, which are becoming increasingly highly integrated and miniaturized, particularly in the manufacturing process of 3D-NAND non-volatile memories and the like.

[0057] Preferred examples of the present invention are described in detail below. However, the materials and blending amounts described in these examples are not intended to limit the scope of the present invention unless otherwise specified.

[0058] Example 1 Hydrofluoric acid (manufactured by Stella Chemifa Corporation, high-purity grade for semiconductors, concentration 50% by mass), an aqueous polyallylamine solution (manufactured by Nittobo Medical Co., Ltd., product name: PAA (registered trademark)-006, polyallylamine concentration 15% by mass, polyallylamine mass average molecular weight 600), and water were mixed and stirred so that the contents of hydrogen fluoride, cationic polyallylamine, and water were the values ​​shown in Table 1. The temperature of this mixture was adjusted to 25°C and left to stand for several hours. In this way, an etching solution (micro-processing treatment agent) according to this example was prepared.

[0059] Examples 2 to 4 In Examples 2 to 4, PAA (registered trademark)-01 (manufactured by Nittobo Medical Co., Ltd., polyallylamine concentration 15% by mass, polyallylamine mass average molecular weight 1,600) was used as the aqueous polyallylamine solution. The contents of the aqueous polyallylamine solution and water were changed to the values ​​shown in Table 1. Except for these, the etching solutions (micro-processing treatment agents) of Examples 2 to 4 were prepared in the same manner as in Example 1.

[0060] (Examples 5 to 7) In Examples 5 to 7, the content of hydrogen fluoride was changed to the value shown in Table 1. Furthermore, PAA (registered trademark)-01 (manufactured by Nittobo Medical Co., Ltd., polyallylamine concentration 15% by mass, polyallylamine mass average molecular weight 1,600) was used as the aqueous polyallylamine solution. Furthermore, the contents of the aqueous polyallylamine solution and water were changed to the values ​​shown in Table 1. Except for these, the etching solutions (micro-processing treatment agents) of Examples 5 to 7 were prepared in the same manner as in Example 1.

[0061] Examples 8 to 10 In Examples 8 to 10, PAA (registered trademark)-05 (manufactured by Nittobo Medical Co., Ltd., polyallylamine concentration 20% by mass, polyallylamine mass average molecular weight 5,000) was used as the aqueous polyallylamine solution. The contents of the aqueous polyallylamine solution and water were changed to the values ​​shown in Table 1. Except for these, the etching solutions (micro-processing treatment agents) of Examples 8 to 10 were prepared in the same manner as in Example 1.

[0062] In Example 11, the contents of hydrogen fluoride and water were changed to the values ​​shown in Table 1. Except for these, an etching solution (fine-processing treatment agent) according to Example 11 was prepared in the same manner as in Example 10.

[0063] Examples 12 to 14 In Examples 12 to 14, PAA (registered trademark)-15C (manufactured by Nittobo Medical Co., Ltd., polyallylamine concentration 15% by mass, polyallylamine mass average molecular weight 15,000) was used as the aqueous polyallylamine solution. The content of the aqueous polyallylamine solution was changed to the value shown in Table 1. Except for this, the etching solutions (micro-processing treatment agents) of Examples 12 to 14 were prepared in the same manner as in Example 1.

[0064] In Example 15, the contents of hydrogen fluoride and water were changed to the values ​​shown in Table 1. Except for these, an etching solution (fine-processing treatment agent) according to Example 15 was prepared in the same manner as in Example 12.

[0065] Examples 16 to 18 In Examples 16 to 18, PAA (registered trademark)-50 (manufactured by Nittobo Medical Co., Ltd., polyallylamine concentration 10% by mass, polyallylamine mass average molecular weight 50,000) was used as the polyallylamine aqueous solution. The content of the polyallylamine aqueous solution was changed to the value shown in Table 1. Except for this, the etching solutions (micro-processing treatment agents) of Examples 16 to 18 were prepared in the same manner as in Example 1.

[0066]

[0067] Examples 19 to 21 In Examples 19 to 21, an allylamine-sodium allylsulfonate copolymer (PAA (registered trademark)-1152, manufactured by Nittobo Medical Co., Ltd., concentration of the allylamine-sodium allylsulfonate copolymer: 20% by mass, mass average molecular weight of the allylamine-sodium allylsulfonate copolymer: 1,500) was used as the water-soluble polymer of component (b). The content of the allylamine-sodium allylsulfonate copolymer was changed to the value shown in Table 2. Except for this, the etching solutions (micro-processing treatment agents) of Examples 19 to 21 were prepared in the same manner as in Example 1.

[0068] Examples 22 to 24 In Examples 22 to 24, partially carbamoylated polyallylamine (PAA (registered trademark)-N5050CL, manufactured by Nittobo Medical Co., Ltd., partially carbamoylated polyallylamine concentration 15% by mass, partially carbamoylated polyallylamine mass average molecular weight 15,000) was used as the water-soluble polymer of component (b). The content of partially carbamoylated polyallylamine was changed to the value shown in Table 2. Except for this, the etching solutions (micro-processing treatment agents) of Examples 22 to 24 were each prepared in the same manner as in Example 1.

[0069] Examples 25 to 27 In Examples 25 to 27, an allylamine amide sulfate polymer (PAA (registered trademark)-SA, manufactured by Nittobo Medical Co., Ltd., allylamine amide sulfate polymer concentration 20 mass %, mass average molecular weight of the allylamine amide sulfate polymer 12,000) was used as the water-soluble polymer of component (b). The content of the allylamine amide sulfate polymer was changed to the value shown in Table 2. Except for this, the etching solutions (micro-processing treatment agents) of Examples 25 to 27 were each prepared in the same manner as in Example 1.

[0070]

[0071] (Comparative Examples 1 to 6, 11 to 13) Hydrofluoric acid (manufactured by Stella Chemifa Corporation, high-purity grade for semiconductors, concentration 50% by mass) and water were mixed and stirred so that the hydrogen fluoride content was the value shown in Table 3. The temperature of this mixed solution was adjusted to 25°C and allowed to stand for several hours. In this way, etching solutions (micro-processing treatment agents) according to Comparative Examples 1 to 6 and 11 to 13 were prepared, respectively.

[0072] Comparative Example 7 Hydrofluoric acid (Semiconductor high-purity grade, manufactured by Stella Chemifa Corporation, concentration 50% by mass), sodium dodecyl sulfate (manufactured by Tokyo Chemical Industry Co., Ltd.), and water were mixed and stirred so that the contents of hydrogen fluoride, sodium dodecyl sulfate, and water were as shown in Table 3. The mixture was adjusted to a temperature of 25°C and allowed to stand for several hours. In this way, an etching solution (micro-processing treatment agent) according to Comparative Example 7 was prepared.

[0073] (Comparative Examples 8 to 10) In Comparative Examples 8 to 10, PAA (registered trademark)-10L-10C (manufactured by Nittobo Medical Co., Ltd., polyallylamine concentration 10% by mass, polyallylamine mass average molecular weight 100,000) was used as the aqueous polyallylamine solution. The contents of the aqueous polyallylamine solution and water were changed to the values ​​shown in Table 3. Except for these, etching solutions (micro-processing treatment agents) according to Comparative Examples 8 to 10 were prepared in the same manner as in Example 1.

[0074] (Comparative Examples 14 to 17) Hydrofluoric acid (manufactured by Stella Chemifa Corporation, high-purity grade for semiconductors, concentration 50% by mass), each nitrogen-containing compound shown in Table 3, and water were mixed and stirred so that the contents of hydrogen fluoride, nitrogen-containing compound, and water were the values ​​shown in Table 3. The temperature of these mixed solutions was adjusted to 25°C and left to stand for several hours. In this way, etching solutions (micro-processing treatment agents) according to Comparative Examples 14 to 17 were prepared, respectively.

[0075]

[0076] (Examples 28 to 50) In Examples 28 to 50, the compounds having a counter ion shown in Table 4 were used. The contents of the compound having a counter ion and water were set to the values ​​shown in Table 4. Except for these, the etching solutions (fine-processing treatment agents) of Examples 28 to 50 were prepared in the same manner as in Example 1.

[0077]

[0078] Comparative Example 18 Hydrofluoric acid (manufactured by Stella Chemifa Corporation, high-purity grade for semiconductors, concentration 50% by mass), diethylenetriamine, water, and hydrochloric acid with a concentration of 36% by mass were mixed and stirred so that the contents of hydrogen fluoride, diethylenetriamine, water, and hydrochloric acid were the values ​​shown in Table 5. The temperature of this mixture was adjusted to 25°C and allowed to stand for several hours. In this way, an etching solution (micro-processing treatment agent) according to Comparative Example 18 was prepared.

[0079] Comparative Example 19 Hydrofluoric acid (manufactured by Stella Chemifa Corporation, high-purity grade for semiconductors, concentration 50% by mass), triethylenetriamine, water, and sulfuric acid with a concentration of 96% by mass were mixed and stirred so that the contents of hydrogen fluoride, triethylenetetramine, water, and sulfuric acid were the values ​​shown in Table 5. The temperature of this mixture was adjusted to 25°C and allowed to stand for several hours. In this way, an etching solution (fine-processing treatment agent) according to Comparative Example 19 was prepared.

[0080] (Comparative Example 20) Hydrofluoric acid (manufactured by Stella Chemifa Corporation, high-purity grade for semiconductors, concentration 50% by mass), water, and acetic acid were mixed and stirred so that the contents of hydrogen fluoride, water, and acetic acid were the values ​​shown in Table 5. The temperature of this mixture was adjusted to 25°C and allowed to stand for several hours. In this way, an etching solution (micro-processing treatment agent) according to Comparative Example 20 was prepared.

[0081]

[0082] (Wet Etching Treatment 1) A silicon wafer (manufactured by Global Net Co., Ltd., diameter: 8 inches, see FIG. 2(a)) was prepared as a workpiece. The wafer had a laminate on the surface of which a silicon thermal oxide film (film thickness: 10 nm) and a polysilicon film (film thickness: 90 nm) were sequentially stacked, and the laminate had multiple trenches (length: 6 mm, width: 250 nm, depth: 100 nm) formed parallel to each other at 250 nm intervals. The silicon wafer was cut into square test piece sizes (length: 2 cm, width: 2 cm) and then subjected to a batch-type wet etching treatment using the etching solutions of the above-mentioned Examples and Comparative Examples. The wet etching treatment was performed by immersing the silicon wafer in etching tanks filled with the respective etching solutions to etch the silicon thermal oxide film, leaving the silicon wafer surface exposed to the etching solutions. The etching time was 3 minutes in Examples 1 to 4, 8 to 10, 12 to 14, and 16 to 50, and Comparative Examples 2 and 20, 30 seconds in Examples 5 to 7 and 11, and Comparative Examples 3 to 7, and 10 minutes in Example 15, and Comparative Examples 1, 11 to 15, and 18 to 19. The liquid temperature of the etching solution was 25°C. The silicon wafer was then removed from the etching tank and immersed in a rinse tank overflowing with ultrapure water, where it was washed for 5 minutes. The silicon wafer was then removed from the rinse tank and dried.

[0083] Next, the cross section of the laminate was observed using a scanning electron microscope (JSM-7800F, manufactured by JEOL Ltd.) for the test piece that had been subjected to wet etching treatment 1, and the amount of etching of the silicon thermal oxide film after the wet etching treatment was measured. The etching rate V1 (nm / min) at an etching temperature (liquid temperature of the etching solution) of 25°C was calculated for each of the etching solutions of Examples 1 to 50 and Comparative Examples 1 to 7, 11 to 15, and 18 to 20 described above. The results are shown in Tables 6 to 10. Note that, for the etching solutions of Comparative Examples 8 to 10, 16, and 17, the polysilicon film was also etched in addition to the silicon thermal oxide film, and as a result, the narrow area expanded in the direction perpendicular to the silicon wafer surface, making it difficult to measure the etching rate V1.

[0084] (Wet Etching Treatment 2) As another workpiece, a silicon wafer (manufactured by Global Net Co., Ltd., diameter: 8 inches, see FIG. 1(a)) with a blanket-like silicon thermal oxide film (film thickness: 10 nm) formed on its surface was prepared. This silicon wafer was subjected to a batch-type wet etching treatment using the etching solutions according to the above-mentioned Examples and Comparative Examples. The wet etching treatment involved immersing the silicon wafer in an etching bath filled with each etching solution, and adjusting the etching time appropriately so that a predetermined amount of silicon thermal oxide film remained. The temperature of the etching solution was set to 25°C. The silicon wafer was then removed from the etching bath and immersed in a rinse bath overflowing with ultrapure water, where it was rinsed for 5 minutes. The silicon wafer was then removed from the rinse bath and dried.

[0085] Next, the thickness of the silicon thermal oxide film was measured before and after the wet etching process using an optical film thickness measurement device (Nanospec II, manufactured by Onto Innovation Inc.), and the change in film thickness due to etching was measured. The etching rate V2 (nm / min) at an etching temperature (etchant temperature) of 25°C was calculated for each of the etching solutions of Examples 1 to 50 and Comparative Examples 1 to 7, 11 to 15, and 18 to 20. The results are shown in Tables 6 to 10.

[0086] (Evaluation of Etching in Narrow Spaces) For the etching solutions according to the above-described Examples and Comparative Examples, the etching performance in narrow spaces was evaluated based on the results of the wet etching process 1 and the wet etching process 2. Specifically, first, the etching rate ratio (V1 / V2(-)) was calculated using the etching rates V1 and V2 calculated in the wet etching process 1 and the wet etching process 2, respectively.

[0087] Next, the improvement rate (%) of the etching rate ratio (V1 / V2(-)) for each of Examples 1 to 50 and Comparative Examples 7, 14-15, and 18-20 was calculated based on the following formula. The results are shown in Tables 6 to 10. Improvement rate (%) = {(V1 / V2) / (V10 / V20) - 1} x 100. V10 (nm / min) represents the etching rate when wet etching process 1 was performed using an etching solution consisting only of HF, with the same HF concentration as that contained in the etching solution of the corresponding Example or Comparative Example. V20 (nm / min) represents the etching rate when wet etching process 2 was performed using an etching solution consisting only of HF, with the same HF concentration as that contained in the etching solution of the corresponding Example or Comparative Example.

[0088] As can be seen from the results in Tables 6 to 10, for each of the etching solutions of Examples 1 to 50, the etching rate ratio (V1 / V2(-)) was 0.75 or more, and the improvement rate was also good. In particular, for the etching solutions of Examples 1 to 5, 8 to 18, and 21 to 50, the improvement rate was 10% or more. This confirmed that each of the etching solutions of Examples 1 to 50 was capable of selectively etching a silicon thermal oxide film well even in narrow areas.

[0089] On the other hand, as already mentioned, with the etching solutions of Comparative Examples 8 to 10, 16, and 17, the polysilicon film was etched along with the silicon thermal oxide film, and these etching solutions were unable to selectively etch the silicon thermal oxide film. Furthermore, with the etching solutions of Comparative Examples 11 to 15 and 18 to 20, the etching rate ratio (V1 / V2(-)) was within the range of 0.67 to 0.72, which was smaller than that of the etching solutions of Examples 1 to 50, and the improvement rate was also poor. This confirmed that with the etching solutions of Comparative Examples 11 to 15 and 18 to 20, the selective etching of the silicon thermal oxide film was not satisfactory in narrow spaces.

[0090] (Evaluation of Foaming and Defoaming Properties) The foaming and defoaming properties of each of the etching solutions of Examples 1 to 50 and Comparative Examples 1 to 7, 11 to 15, and 18 to 20 were evaluated by the following method.

[0091] First, 20 ml of each etching solution was poured into a styrene bottle (internal volume: 40 ml). The liquid level of each etching solution immediately after pouring was 25 mm. Next, each styrene bottle was shaken for 10 seconds to generate bubbles, and then allowed to stand. Next, the bubble height (the height from the liquid surface of the etching solution to the apex of the highest bubble) after leaving it to stand for 10 seconds and after leaving it to stand for 60 seconds was measured visually.

[0092] The time until the bubbles generated by shaking disappeared (defoaming time) was measured. More specifically, the polystyrene bottle was shaken for 10 seconds, then allowed to stand, and the time required for the ring of bubbles adhering around the entire inner wall of the polystyrene bottle to break up was measured (see Figure 3). The results are shown in Tables 6 to 10. Note that Figure 3 is a plan view schematically showing the state of bubbles of the etching solution adhering to the inner wall of the polystyrene bottle.

[0093] As can be seen from Tables 6 to 10, the generation of foam was effectively suppressed in all of the etching solutions of Examples 1 to 50, and any foam that did occur was able to be defoamed in less than 10 seconds after being left to stand. On the other hand, the etching solution of Comparative Example 7 filled the space inside the polystyrene bottle with foam, and a larger volume of foam was generated compared to the etching solutions of Examples 1 to 50. Furthermore, the foam could not be defoamed even after 300 seconds had passed after the polystyrene bottle was left to stand.

[0094]

[0095]

[0096]

[0097]

[0098]

[0099] 1 Substrate 2 Silicon oxide film 3 Polysilicon film 4 Trench

Claims

1. A fine processing agent for selectively fine processing a silicon oxide film on a workpiece having at least the silicon oxide film, comprising: (a) hydrogen fluoride in a content of 25 mass% or less relative to the total mass of the fine processing agent; and (b) hydrogen fluoride in a content of 1 x 10 relative to the total mass of the fine processing agent. －４ % by mass or more and 1% by mass or less and having a mass average molecular weight of 600 or more and 50,000 or less; and (c) water, wherein the water-soluble polymer contains a structural unit having a primary amino group and / or a secondary amino group.

2. (d) The content of the fine processing agent relative to the total mass is 1 x 10 －４ % by mass or more and 1% by mass or less, － ,Br － , C.H. ３ COO － , HSO ４ － , S.O. ４ ２－ , NO ３ － , H ２ P.O. ４ － , H.P.O. ４ ２－ and P.O. ４ ３－ 2. The fine processing treatment agent according to claim 1, further comprising a compound having at least one counter ion selected from the group consisting of:

3. The fine processing agent according to claim 1, wherein the structural unit is represented by any one of the following chemical formulas (1) to (4).

4. The fine processing treatment agent according to claim 2, wherein the compound having a counter ion is an ammonium salt, a potassium salt, or a carboxylic acid.

5. The fine processing agent according to claim 4, wherein the ammonium salt is at least one selected from the group consisting of ammonium chloride, ammonium bromide, ammonium acetate, ammonium sulfate, ammonium nitrate, diammonium hydrogen phosphate, and triammonium phosphate.

6. The micro-processing treatment agent according to claim 4, wherein the potassium salt is potassium acetate.

7. The micro-processing treatment agent according to claim 4, wherein the carboxylic acid is acetic acid.

8. The micro-processing treatment agent according to claim 1, which is a surfactant-free treatment agent.

9. A micro-processing method using the micro-processing agent according to any one of claims 1 to 8 to selectively micro-process the silicon oxide film on the workpiece having at least the silicon oxide film.

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