Microfabrication agents and microfabrication methods

Abstract

A microprocessing agent and microprocessing method are provided that reduce or suppress foaming, exhibit excellent defoaming properties, and can effectively and selectively microprocess silicon oxide films even in narrow areas, thereby improving yield and output. The microprocessing agent of this invention is for microprocessing a workpiece having at least a silicon oxide film (2), comprising: (a) hydrogen fluoride in a content of 25% by mass or less relative to the total mass of the aforementioned microprocessing agent; (b) at least one water-soluble polymer in a content of 1×10⁻⁴% by mass or more but less than 1% by mass relative to the total mass of the aforementioned microprocessing agent, having a mass average molecular weight of 600 to 50,000; and (c) water, wherein the aforementioned water-soluble polymer comprises building units having primary and / or secondary amino groups.

Description

[Technical Field]

[0001] This invention relates to a microprocessing agent and a microprocessing method used in the manufacture of semiconductor devices, liquid crystal display devices, micromachine (micro electromechanical systems; MEMS) devices, including microprocessing processes such as etching and cleaning, and particularly to a microprocessing agent and a microprocessing method used in the microprocessing of silicon oxide films. [Previous Technology]

[0002] Examples of semiconductor device manufacturing processes that utilize wet etching include 3D-NAND non-volatile memory. Previous NAND non-volatile memory was planar and has achieved increased capacity through miniaturization, but this has led to reduced electrical reliability, and miniaturization has reached its limits. Therefore, by using a trench type where memory cells are stacked vertically, 3D-NAND non-volatile memory has been developed that achieves increased capacity without shrinking memory cells.

[0003] The manufacturing process of this 3D-NAND type non-volatile memory includes, for example, a wet etching step in which the silicon oxide film is selectively removed as a sacrificial layer for a stack formed by sequentially depositing a silicon oxide film and a polysilicon film on a silicon substrate. The wet etching step utilizes the difference in etching rates between the silicon oxide film and the polysilicon film as the etching solution used, and examples include etching solutions composed of hydrofluoric acid, or etching agents containing dilute hydrofluoric acid and surfactants (Patent Document 1), etc.

[0004] However, with the miniaturization of semiconductor devices, it is required to control the wet etching process at the nanometer level. In particular, in stacks containing silicon oxide films, there is a need to selectively remove the silicon oxide film to form elongated recesses with narrow and deep openings. However, the etching solution composed of hydrofluoric acid is difficult to efficiently penetrate to the interior of such narrow recesses (i.e., down to the narrow region). Therefore, there is a problem that the etching rate of the silicon oxide film in the narrow recesses is lower than the etching rate of the same size recesses with openings. Non-Patent Document 1 also points out this problem. That is, according to Non-Patent Document 1, the etching rate under certain conditions shows a decrease as the etched area narrows. Furthermore, this decrease in etching rate is considered to be due to the influence of the double layer formed near the solid-liquid interface. Therefore, a decrease in the etching rate in narrow recesses can lead to a decrease in yield due to an increase in etching time, or a deterioration in yield due to the inability to micronize the laminate into the desired structure.

[0005] Furthermore, Patent Document 1 states that an etchant containing dilute hydrofluoric acid and a surfactant can increase the etching rate of silicon oxide films in narrow recesses. However, due to the presence of the surfactant, bubbles are generated during use. As a result, the etchant does not make uniform contact with the silicon oxide film, leading to uneven etching and the problem of uneven etching. [Prior Art Documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2021-48369 [Non-Patent Document]

[0007] [Non-Patent Literature 1] Atsushi Okuyama, et al., Solid State Phenomena, Vol. 219, pp 115-118, 2014 [Summary of the Invention]

[0008] [Problem to be Solved by the Invention] The present invention was made in view of the aforementioned problems, and its object is to provide a microprocessing agent and microprocessing method that reduces or inhibits foaming, has excellent defoaming properties, and can effectively perform selective microprocessing of silicon oxide films even in narrow areas, thereby improving yield and output. [Means for Solving the Problem]

[0009] In order to solve the aforementioned problems, the microprocessing agent of the present invention is a microprocessing agent for selectively microprocessing the aforementioned silicon oxide film on a workpiece having at least a silicon oxide film, characterized in that it comprises (a) hydrogen fluoride in a content of less than 25% by mass relative to the total mass of the aforementioned microprocessing agent, (b) at least one water-soluble polymer in a content of more than 1×10-4% by mass and less than 1% by mass relative to the total mass of the aforementioned microprocessing agent, having a mass average molecular weight of more than 600 and less than 50,000, and (c) water, wherein the aforementioned water-soluble polymer comprises building units having primary amine groups and / or secondary amine groups.

[0010] According to the aforementioned configuration, by reducing the hydrogen fluoride content to 25% by mass or less, the etching rate can be suppressed from becoming excessive during etching of the silicon oxide film. As a result, the silicon oxide film, and other films such as polycrystalline silicon films, can be prevented from being etched together, and the selective etching performance of the silicon oxide film can be well maintained. Furthermore, by containing a water-soluble polymer comprising building blocks having primary and / or secondary amine groups and having a mass average molecular weight of 600 to 50,000 within a range of 1×10⁻⁴% by mass or less, for example, in a laminate containing a silicon oxide film, when a narrow and deep recess is formed by selectively removing the silicon oxide film, the etching rate of the silicon oxide film in such a narrow region can also be well maintained. As a result, the aforementioned configuration can suppress the increase in etching time of the silicon oxide film and improve yield. Furthermore, because it reduces or inhibits bubbling and has excellent defoaming properties, it can be made to penetrate narrow areas more easily than conventional microprocessing agents. Therefore, it can prevent uneven microprocessing caused by bubbling and can effectively perform microprocessing in narrow areas of stacks containing silicon oxide films, thereby improving yield.

[0011] Furthermore, according to the aforementioned composition, it is preferable to include (d) a compound having at least one relative ion selected from the group consisting of Cl-, Br-, CH3COO-, HSO4-, SO4 2-, NO3-, H2PO4-, HPO4 2-, and PO4 3-, in a content ranging from 1×10-4% to 1% relative to the total mass of the aforementioned microprocessing agent. By including the compound having the relative ion in a content ranging from 1×10-4% to 1% relative to the total mass of the microprocessing agent, bubbling can be suppressed while maintaining the etching rate of the silicon oxide film in narrow regions more effectively. As a result, compared with conventional microprocessing agents, even in selective microprocessing of narrow regions of the silicon oxide film, a further improvement in yield and productivity can be achieved.

[0012] In the aforementioned configuration, it is preferable that the aforementioned structural unit is represented by any one of the following chemical formulas (1) to (4).

[0013]

[0014] Furthermore, in the aforementioned configuration, the aforementioned compound having a relative ion is preferably an ammonium salt, a potassium salt, or a carboxylic acid.

[0015] Furthermore, in the aforementioned composition, the aforementioned ammonium salt is preferably selected from at least one of the group consisting of ammonium chloride, ammonium bromide, ammonium acetate, ammonium sulfate, ammonium nitrate, diammonium hydrogen phosphate and triammonium phosphate.

[0016] Furthermore, in the aforementioned composition, potassium salt is preferably potassium acetate.

[0017] Furthermore, in the aforementioned composition, the aforementioned carboxylic acid is preferably acetic acid.

[0018] Furthermore, the aforementioned microprocessing agent is preferably a surfactant-free agent. By making a surfactant-free microprocessing agent, foaming can be further prevented during use. This reduces uneven contact between the microprocessing agent and the silicon oxide film caused by foaming, and further prevents uneven etching.

[0019] In order to solve the aforementioned problems, the micro-processing method of the present invention is characterized by using the aforementioned micro-processing agent to selectively micro-process the aforementioned silicon oxide film on the subject having at least a silicon oxide film.

[0020] According to the aforementioned configuration, the aforementioned microprocessing agent can reduce or suppress the generation of bubbles, and at the same time, it can effectively perform selective microprocessing on the silicon oxide film. Therefore, with the aforementioned configuration, for example, in semiconductor manufacturing processes such as 3D-NAND type non-volatile memory, when performing selective microprocessing on the silicon oxide film in narrow areas, the etching rate of the silicon oxide film can also be well maintained. As a result, the increase in etching time of the silicon oxide film is suppressed, thereby increasing yield. Furthermore, since the occurrence of bubbles is reduced or suppressed and the defoaming property is also excellent, compared with conventional microprocessing agents, the microprocessing agent can be made to easily penetrate into narrow areas. Therefore, uneven microprocessing caused by uneven etching due to the generation of bubbles can be prevented, and microprocessing of the silicon oxide film in narrow areas can be effectively performed, thereby also increasing yield. [Effects of the Invention]

[0021] The present invention achieves the following effects by means of the foregoing description. That is, according to the present invention, a microprocessing agent and a microprocessing method can be provided, which can reduce or suppress foaming and have excellent defoaming properties, and can selectively microprocess silicon oxide films even in narrow areas, thereby improving yield and output.

Implementation Method

[0023] (Microfabrication Agent) The following describes a microfabrication agent according to one embodiment of the present invention. The microfabrication agent of this embodiment comprises at least (a) hydrogen fluoride, (b) at least one water-soluble polymer, and (c) water. Furthermore, the microfabrication agent of this embodiment is preferably further comprising a compound having a relative ion.

[0024] When selectively micro-processing the silicon oxide film in a workpiece having at least a silicon oxide film, the micro-processing agent of this embodiment is suitable for use. In this specification, "micro-processing" refers to etching processes that micro-process the surface or interior of the workpiece, and cleaning processes on the surface of the workpiece. When etching is applied to the workpiece, the micro-processing agent of this embodiment functions as an etching solution. The workpiece is not particularly limited, and examples include, for instance, a laminate formed by sequentially depositing a silicon oxide film and a polycrystalline silicon film on a substrate. Furthermore, when cleaning is applied to the surface of the workpiece, the micro-processing agent of this embodiment functions as a cleaning solution.

[0025] The content of hydrogen fluoride in the aforementioned component (a) is in the range of 25% by mass or less relative to the total mass of the microprocessing agent, preferably in the range of 0.1% by mass or more to 10% by mass, and more preferably in the range of 1% by mass or more to 5% by mass. By making the content of hydrogen fluoride 25% by mass or less, it is possible to prevent the etching rate of the silicon oxide film from becoming too high, which would lead to a decrease in the selective etching performance of other films, such as polycrystalline silicon films, and a decrease in the controllability of microprocessing. Furthermore, the hydrogen fluoride content relative to the total mass of the microprocessing agent 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, or 25.0% by mass, or it can be within any two of the values ​​shown in this example.

[0026] The water-soluble polymer of component (b) above comprises a building unit having at least a primary amine group and / or a secondary amine group. Examples of primary amine groups include, for example, the -NH2 group. Examples of secondary amine groups include, for example, the -NH group. Among these amine groups, the primary amine group is preferred in this embodiment, and the -NH2 group is more preferred.

[0027] As a building block having a primary amine group and / or a secondary amine group, examples can be given by any of the following chemical formulas (1) to (4).

[0028]

[0029] Specific examples of water-soluble polymers include cationic water-soluble polymers and amphoteric water-soluble polymers. Examples of cationic water-soluble polymers include, for example, polyallylamine (chemical formula (5) below), partially-carbamoylated polyallylamine (chemical formula (6) below), and allyl amidesulfate polymer (chemical formula (7) below).

[0030]

[0031] Furthermore, examples of amphoteric water-soluble polymers include, for example, 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 monomeric component comprising a monomer having at least a primary amino group and / or a secondary amino group. Examples of monomers include, for example, allylamine, aminomethylated allylamine, carboxymethylated allylamine, and allylaminoamine sulfate. Furthermore, the aforementioned monomeric component may also contain other monomers, in which case the water-soluble polymer can be obtained as a copolymer of the aforementioned monomers and other monomers. Examples of other monomers include, for example, sodium allyl sulfonate and maleic acid. Moreover, in water-soluble polymers, for example, by polymerizing the carboxyl group of a water-soluble (meth)acrylic acid polymer with ethylamine, it is also possible to obtain a building block having a primary amino group and / or a secondary amino group. Furthermore, the term "water-soluble (meth)acrylic acid polymer" refers to both water-soluble acrylic acid polymers and water-soluble methacrylic acid polymers.

[0034] The mass average molecular weight of the water-soluble polymer is in the range of 600 to 50,000, preferably in the range of 1,500 to 50,000. If the mass average molecular weight of the water-soluble polymer is 600 or higher, for example, the selectivity of the etching rate of the silicon oxide film to the polycrystalline silicon film can be well maintained, and the controllability of microprocessing can be prevented from decreasing. On the other hand, if the mass average molecular weight of the water-soluble polymer is 50,000 or lower, microprocessing of materials other than the silicon oxide film, such as the polycrystalline silicon film, can be inhibited, thereby preventing the controllability of microprocessing from decreasing. Furthermore, the mass average molecular weight of the water-soluble polymer is, 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 any two of the values ​​exemplified here. Furthermore, the mass average molecular weight (Mw) of water-soluble polymers can be measured by methods such as gel permeation chromatography (GPC), osmotic pressure method, viscosity method, light scattering method, or sedimentation velocity method.

[0035] The content of the water-soluble polymer relative to the total mass of the microprocessing agent is in the range of 1×10⁻⁴ mass% to 1% mass, preferably in the range of 1×10⁻³ mass% to 1% mass, and more preferably in the range of 1×10⁻³ mass% to 1×10⁻¹ mass%. By making the content of the water-soluble polymer 1×10⁻⁴ mass% or more, the selectivity of the etching rate of the silicon oxide film to the polycrystalline silicon film, etc., can be well maintained, and the controllability of microprocessing can be prevented from decreasing. On the other hand, by making the content of the water-soluble polymer 1% mass% or less, microprocessing of the polycrystalline silicon film and other materials other than the silicon oxide film can be suppressed, and the controllability of microprocessing can be prevented from decreasing. Furthermore, the content of water-soluble polymer relative to the total mass of the microprocessing agent is, for example, 1×10⁻⁴, 1×10⁻³, 1×10⁻², 2×10⁻², 3×10⁻², 4×10⁻², 5×10⁻², 6×10⁻², 7×10⁻², 8×10⁻², 9×10⁻², 1×10⁻¹, 2×10⁻¹, 3×10⁻¹, 4×10⁻¹, 5×10⁻¹, 6×10⁻¹, 7×10⁻¹, 8×10⁻¹, 9×10⁻¹, 1% by mass, or it can be within any two of the values ​​shown in this example.

[0036] Water-soluble polymers can be made from two or more different types of polymers. Furthermore, the term "different types of polymers" here refers not only to polymers with different molecular structures, but also to polymers with the same molecular structure but different mass average molecular weights.

[0037] The compound having a relative ion in component (d) above is a compound having at least one ion selected from the group consisting of Cl-, Br-, CH3COO-, HSO4-, SO4 2-, NO3-, H2PO4-, HPO4 2-, and PO4 3-. Ammonium salts, potassium salts, or carboxylic acids are preferred as compounds having a relative ion. Furthermore, examples of ammonium salts include 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. Potassium salts include, for example, potassium acetate. Carboxylic acids include, for example, acetic acid. Among the exemplified compounds, from the viewpoint of a semiconductor manufacturing solution, ammonium acetate is preferred as it contains little or no metallic or anionic impurities.

[0038] The content of the compound having a relative ion is in the range of 1×10⁻⁴ mass% to 1% mass% relative to the total mass of the microfabrication agent, preferably in the range of 1×10⁻³ mass% to 5×10⁻¹ mass%. By making the content of the compound having a relative ion 1×10⁻⁴ mass% or more, the etching rate of silicon oxide films in narrow recesses can be further improved. On the other hand, by making the content of the compound having a relative ion 1% or less, the selectivity of the etching rate of the silicon oxide film to polycrystalline silicon films, etc., can be well maintained, and the controllability of microfabrication can be prevented from decreasing. Furthermore, the content of compounds having relative ions is, for example, 1×10⁻⁴, 1×10⁻³, 1×10⁻², 2×10⁻², 3×10⁻², 4×10⁻², 5×10⁻², 6×10⁻², 7×10⁻², 8×10⁻², 9×10⁻², 1×10⁻¹, 2×10⁻¹, 3×10⁻¹, 4×10⁻¹, 5×10⁻¹, 6×10⁻¹, 7×10⁻¹, 8×10⁻¹, 9×10⁻¹, 1% by mass, or it can be within the range of any two of the values ​​shown in this example.

[0039] The water contained in the aforementioned component (c) of the microprocessing agent of this embodiment is not particularly limited, but pure water, ultrapure water, etc. are preferred.

[0040] The water content relative to the total mass of the microprocessing agent is preferably 73% by mass or more, preferably 83% by mass or more, and especially preferably 93% by mass or more.

[0041] The microprocessing agent of this embodiment is preferably a surfactant-free agent. By being surfactant-free, the microprocessing agent can better prevent foaming during use. This reduces uneven contact between the microprocessing agent and the silicon oxide film caused by foaming, further preventing uneven etching. Furthermore, examples of surfactants that are not desirable to be included in the microprocessing agent of this embodiment include, for example, monoalkyl sulfates.

[0042] The microprocessing agent of this embodiment may be composed solely of hydrogen fluoride, a water-soluble polymer, and water, or it may be composed solely of compounds having relative ions added to these components. Furthermore, the microprocessing agent of this embodiment may also contain other additives without hindering the effects of the present invention. Examples of other additives include hydrogen peroxide and chelating agents. Moreover, the content of other additives can be appropriately set as necessary.

[0043] The defoaming time of the microprocessing agent in this embodiment is preferably less than 300 seconds, and more preferably less than 60 seconds. This allows the microprocessing agent to efficiently penetrate narrow areas when supplied to the workpiece for microprocessing. Furthermore, it prevents uneven contact between the microprocessing agent and the silicon oxide film caused by foaming, thus avoiding uneven microprocessing processes such as etching. The defoaming time can be measured using the method described in the embodiments.

[0044] There is no particular limitation on the manufacturing method of the microprocessing agent of this embodiment, and various methods can be used. For example, water-soluble polymers, compounds with relative ions of any component, and other additives can be added to hydrofluoric acid in any order or simultaneously to prepare the microprocessing agent of this embodiment.

[0045] (Microfabrication Method) Next, the following describes a microfabrication method using the microfabrication agent of this embodiment. The microfabrication agent of this embodiment is suitable for selectively microfabricating a silicon oxide film having a thickness of at least 5 nm or 10 nm on a workpiece.

[0046] The microfabrication method of this embodiment is suitable for selectively microfabriking a silicon oxide film 2 that has been formed in a laminated form on a substrate 1, as shown in Figures 1(a) and 1(b). Figure 1(a) is a cross-sectional view showing the silicon oxide film 2 formed in a laminated form on the substrate 1, and Figure 1(b) is a cross-sectional view showing the silicon oxide film 2 after microfabrication using the microfabrication agent of this embodiment.

[0047] Furthermore, the microprocessing agent of this embodiment is also suitable for selectively microprocessing silicon oxide films in a multilayer structure as shown in FIG. 2(a). The multilayer structure shown in FIG. (a) has a structure formed by sequentially depositing a silicon oxide film 2 and a polycrystalline silicon film 3, which serve as sacrificial layers, on a substrate 1. The multilayer system is formed with a plurality of trenches 4 arranged in parallel, and the trenches 4 are partially exposed on the surface of the substrate 1. When the microprocessing agent is supplied to the substrate 1, the microprocessing agent reduces or suppresses the generation of bubbles and simultaneously penetrates into the interior of the multilayer structure from the trenches 4, contacting and removing the exposed areas of the silicon oxide film 2. Alternatively, even if bubbles are generated, the microprocessing agent will defoam over time, as shown in FIG. 2(b), removing the silicon oxide film 2 in the narrow region R. The narrow region R refers to the space between the substrate 1 and the polycrystalline silicon film 3. Furthermore, Figure 2(a) is a cross-sectional view showing the appearance of the silicon oxide film 2 and the polycrystalline silicon film 3 sequentially deposited on the substrate 1, and Figure 2(b) is a cross-sectional view showing the appearance of the narrow region of the silicon oxide film 2 after microprocessing is applied using the microprocessing agent of this embodiment.

[0048] The micro-processing agent of this embodiment can be used in various wet etching methods. As wet etching methods, there are batch etching and monolithic etching methods, and the micro-processing agent of this invention can be used in either method. In the case of batch etching methods, since a large number of wafers are processed in a single wet etching operation, it is superior in terms of yield. However, in semiconductor manufacturing processes moving towards miniaturization of semiconductor devices, there is a problem of cross-contamination within the etching tank. In the case of monolithic wet etching methods, although the concern about cross-contamination is less than that of batch etching methods, the yield is worse than that of batch etching methods.

[0049] Furthermore, methods for bringing the microprocessing agent into contact with the workpiece include immersion and spraying. Among these contact methods, immersion is preferred because it can reduce or suppress compositional changes in the microprocessing agent caused by evaporation during the process.

[0050] When a microfabrication agent is used as an etching solution, the etching temperature (i.e., the liquid temperature of the microfabrication agent) is preferably below 50°C, more preferably between 5°C and 50°C, even more preferably between 15°C and 35°C, and particularly preferably between 20°C and 30°C. By setting the etching temperature to below 50°C, the evaporation of the microfabrication agent can be suppressed, and changes in the composition of the microfabrication agent can be prevented. Furthermore, it prevents the etching rate from becoming difficult to control due to the evaporation of the microfabrication agent. Moreover, the etching temperature can be, for example, 5, 10, 15, 20, 25, 30, 35, or 50°C, or it can be within any two of the values ​​shown in this example.

[0051] Furthermore, when using the microprocessing agent of this embodiment to etch the layered silicon oxide film 2 as shown in FIG. 1(a), the etching rate within the aforementioned etching temperature range is preferably 1 nm / min or higher, more preferably 4 nm / min or higher, and even more preferably 25 nm / min or higher. By setting the etching rate for the layered silicon oxide film 2 to 1 nm / min or higher, the selective microprocessing of the layered silicon oxide film 2 can be improved. As a result, the time required for microprocessing such as wet etching of the silicon oxide film 2 can be shortened, and the reduction in processing efficiency can be suppressed. Moreover, by setting the etching rate to 270 nm / min or lower, the controllability of the etching amount of the silicon oxide film 2 can be prevented from decreasing, and its practicality as an etching solution in semiconductor manufacturing processes can be maintained. Furthermore, the etching rate for the layered silicon oxide film 2 is, for example, 1, 4, 25, 30, 35, 65, 110, 180, 270 nm / min, or it can be within any two of the values ​​shown in this example.

[0052] Furthermore, when using the microprocessing agent of this embodiment to etch a narrow region of the silicon oxide film 2 in the multilayer formed on the substrate 1, as shown in FIG2(a), the etching rate within the aforementioned etching temperature range is preferably 1 nm / min or higher, more preferably 4 nm / min or higher, even more preferably 20 nm / min or higher, and even more preferably 25 nm / min or higher. By setting the etching rate of the silicon oxide film 2 in the narrow region to 1 nm / min or higher, the selective microprocessing of the silicon oxide film 2 can be improved. As a result, the time required for microprocessing such as wet etching of the silicon oxide film 2 can be shortened, and the reduction in processing efficiency can be suppressed. Moreover, by setting the etching rate to 270 nm / min or lower, the controllability of the etching amount of the silicon oxide film 2 can be prevented from decreasing, and the practicality as an etching solution in semiconductor manufacturing processes can be maintained. Furthermore, the etching rate for the silicon oxide film 2 in the narrow region is, for example, 1, 4, 20, 25, 30, 50, 90, 150, 220, or 270 nm / min, or it can be within any two of the values ​​shown in this example.

[0053] Here, the silicon oxide film 2 is not particularly limited as long as it contains silicon (Si) and oxygen (O). Specific examples include, for instance, natural oxide films, chemical oxide films, silicon thermal oxide films, undoped silicate glass films, phosphorus-doped silicate glass films, boron-doped silicate glass films, phosphorus-boron-doped silicate glass films, tetraethyl silicate (TEOS) films, fluorine-containing silicon oxide films, carbon-containing silicon oxide films, nitrogen-containing silicon oxide films, spin-on glass (SOG) films, and spin-on dielectric (SOD) films.

[0054] Furthermore, the natural oxide film in silicon oxide film 2 refers to a silicon oxide film formed on silicon under atmospheric exposure at room temperature. Also, a chemical oxide film refers to a film formed on silicon, for example, during washing with sulfuric acid and hydrogen peroxide. A silicon thermal oxide film refers to a film formed at a high temperature of 800-1000°C by supplying water vapor or oxygen. Undoped silicate glass films, phosphorus-doped silicate glass films, boron-doped silicate glass films, phosphorus-boron-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 depositing silicon oxide films using CVD (chemical vapor deposition) methods by supplying raw material gases such as silanes. SOG films and SOD films can be formed by coating methods such as spin coaters.

[0055] Furthermore, examples of the aforementioned CVD methods include plasma-enhanced chemical vapor deposition (PECVD), atomic layer deposition (ALD), metal-organic chemical vapor deposition (MOCVD), catalytic chemical vapor deposition (Cat-CVD), thermal CVD, epitaxial CVD, and other film formation methods. Similarly, examples of the aforementioned PVD methods include vacuum evaporation, ion plating, ion beam evaporation, sputtering, and other film formation methods.

[0056] As described above, the microprocessing agent and the microprocessing method using the present embodiment can selectively microprocess silicon oxide films in narrow regions within a laminate formed by sequentially depositing silicon oxide films and other films on a substrate. Furthermore, when microprocessing silicon oxide films in narrow regions, the microprocessing agent and the microprocessing method of the present embodiment can suppress bubble formation, or even if bubbles are formed, eliminate them as early as possible. Therefore, uneven microprocessing of the silicon oxide film caused by bubble formation can be prevented. As a result, the microprocessing agent and the microprocessing method using the present embodiment are suitable for selective microprocessing of silicon oxide films in manufacturing processes moving towards high integration and miniaturization of semiconductor devices, especially in manufacturing processes of 3D-NAND type non-volatile memory. [Example]

[0057] Hereinafter, suitable embodiments of the present invention will be described in detail by way of example. However, unless otherwise specified, the scope of the present invention is not limited to the materials or amounts of admixtures described in these embodiments.

[0058] (Example 1) Hydrofluoric acid (manufactured by Stella Chemifa, Ltd., high purity grade for semiconductors, concentration 50% by mass), polyallylamine aqueous solution (manufactured by Nittobo Medical, Ltd., trade name: PAA (registered trademark)-006, polyallylamine concentration 15% by mass, polyallylamine mass average molecular weight 600), and water were mixed and stirred such that the contents of hydrogen fluoride, cationic polyallylamine, and water were as shown in Table 1. The mixture was then heated to 25°C and allowed to stand for several hours. This prepared the etching solution (microfabrication agent) of this example.

[0059] (Examples 2-4) In Examples 2-4, PAA (registered trademark)-01 (manufactured by Nittobo Medical (Co., Ltd., with a polyallylamine concentration of 15% by mass and a polyallylamine mass average molecular weight of 1,600) was used as an aqueous solution of polyallylamine. Furthermore, the contents of the aqueous solution of polyallylamine and water were changed to the values ​​shown in Table 1. These external processes were performed in the same manner as in Example 1, and etching solutions (microfabrication agents) for Examples 2-4 were prepared accordingly.

[0060] (Examples 5-7) In Examples 5-7, the content of hydrogen fluoride was changed to the values ​​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 an aqueous solution of polyallylamine. The content of the polyallylamine aqueous solution and water was also changed to the values ​​shown in Table 1. These external processes were performed in the same manner as in Example 1, and etching solutions (microfabrication agents) for Examples 5-7 were prepared accordingly.

[0061] (Examples 8-10) In Examples 8-10, PAA (registered trademark)-05 (manufactured by Nittobo Medical (Co., Ltd., with a polyallylamine concentration of 20% by mass and a polyallylamine mass average molecular weight of 5,000) was used as an aqueous solution of polyallylamine. Furthermore, the contents of the aqueous solution of polyallylamine and water were changed to the values ​​shown in Table 1. These external processes were performed in the same manner as in Example 1, and etching solutions (microfabrication agents) for Examples 8-10 were prepared accordingly.

[0062] (Example 11) In Example 11, the contents of hydrogen fluoride and water were changed to the values ​​shown in Table 1. These external components were prepared in the same manner as in Example 10 to produce the etching solution (microfabrication agent) of Example 11.

[0063] (Examples 12-14) In Examples 12-14, PAA (registered trademark)-15C (manufactured by Nittobo Medical (Co., Ltd., with a polyallylamine concentration of 15% by mass and a polyallylamine mass average molecular weight of 15,000) was used as an aqueous solution of polyallylamine. Furthermore, the content of the aqueous solution of polyallylamine was varied to the values ​​shown in Table 1. These external processes were performed in the same manner as in Example 1, and etching solutions (microfabrication agents) for Examples 12-14 were prepared accordingly.

[0064] (Example 15) In Example 15, the contents of hydrogen fluoride and water were changed to the values ​​shown in Table 1. The etching solution (microfabrication agent) of Example 15 was prepared by operating in the same manner as in Example 12.

[0065] (Examples 16-18) In Examples 16-18, PAA (registered trademark)-50 (manufactured by Nittobo Medical (Co., Ltd., with a polyallylamine concentration of 10% by mass and a polyallylamine mass average molecular weight of 50,000) was used as an aqueous solution of polyallylamine. Furthermore, the content of the aqueous solution of polyallylamine was varied to the values ​​shown in Table 1. These procedures were performed in the same manner as in Example 1, and etching solutions (microfabrication agents) for Examples 16-18 were prepared accordingly.

[0066]

[0067] (Examples 19-21) In Examples 19-21, allylamine-sodium allyl sulfonate copolymer (PAA (registered trademark)-1152, manufactured by Nittobo Medical (Co., Ltd., with an allylamine-sodium allyl sulfonate copolymer concentration of 20% by mass and an allylamine-sodium allyl sulfonate copolymer mass average molecular weight of 1,500) was used as the water-soluble polymer for component (b). Furthermore, the content of allylamine-sodium allyl sulfonate copolymer was varied to the values ​​shown in Table 2. These external processes were performed in the same manner as in Example 1, and etching solutions (microfabrication agents) for Examples 19-21 were prepared accordingly.

[0068] (Examples 22-24) In Examples 22-24, partially aminomethylated polyallylamine (PAA (registered trademark)-N5050CL, manufactured by Nittobo Medical (Co., Ltd., with a concentration of 15% by mass and a mass-average molecular weight of 15,000) was used as the water-soluble polymer of component (b). Furthermore, the content of partially aminomethylated polyallylamine was varied to the values ​​shown in Table 2. These external processes were performed in the same manner as in Example 1, and etching solutions (microfabrication agents) for Examples 22-24 were prepared accordingly.

[0069] (Examples 25-27) In Examples 25-27, allylaminoamide sulfate polymer (PAA (registered trademark)-SA, manufactured by Nittobo Medical (Co., Ltd., with an allylaminoamide sulfate polymer concentration of 20% by mass and an allylaminoamide sulfate polymer mass average molecular weight of 12,000) was used as the water-soluble polymer for component (b). Furthermore, the content of the allylaminoamide sulfate polymer was varied to the values ​​shown in Table 2. These external processes were performed in the same manner as in Example 1, and etching solutions (microfabrication agents) for Examples 25-27 were prepared accordingly.

[0070]

[0071] (Comparative Examples 1-6, 11-13) Hydrofluoric acid (manufactured by Stella Chemifa, high purity grade for semiconductors, concentration 50% by mass) and water were mixed and stirred so that the hydrogen fluoride content would be as shown in Table 3. The mixture was then heated to 25°C and allowed to stand for several hours. This was used to prepare etching solutions (microfabrication agents) for Comparative Examples 1-6 and 11-13, respectively.

[0072] (Comparative Example 7) Hydrofluoric acid (manufactured by Stella Chemifa, Ltd., high purity grade for semiconductors, 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 then heated to 25°C and allowed to stand for several hours. This prepared the etching solution (microfabrication agent) of Comparative Example 7.

[0073] (Comparative Examples 8-10) In Comparative Examples 8-10, 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 an aqueous solution of polyallylamine. Furthermore, the contents of the aqueous solution of polyallylamine and water were changed to the values ​​shown in Table 3. These external processes were performed in the same manner as in Example 1, and the etching solutions (microfabrication agents) of Comparative Examples 8-10 were prepared accordingly.

[0074] (Comparative Examples 14-17) Hydrofluoric acid (manufactured by Stella Chemifa, high purity grade for semiconductors, concentration 50% by mass), the nitrogen-containing compounds shown in Table 3, and water were mixed and stirred so that the contents of hydrogen fluoride, nitrogen-containing compounds, and water were respectively as shown in Table 3. The mixtures were then heated to a temperature of 25°C and allowed to stand for several hours. This was used to prepare the etching solutions (microfabrication agents) for Comparative Examples 14-17.

[0075]

[0076] (Examples 28-50) In Examples 28-50, the compounds shown in Table 4 were used as having relative ions. Furthermore, the contents of the compounds having relative ions and water were set as shown in Table 4. These external processes were performed in the same manner as in Example 1, and the etching solutions (microfabrication agents) of Examples 28-50 were prepared respectively.

[0077]

[0078] (Comparative Example 18) Hydrofluoric acid (manufactured by Stella Chemifa, semiconductor high purity grade, 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 as shown in Table 5. The mixture was then heated to a temperature of 25°C and allowed to stand for several hours. This prepared the etching solution (microfabrication agent) of Comparative Example 18.

[0079] (Comparative Example 19) Hydrofluoric acid (manufactured by Stella Chemifa, 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 as shown in Table 5. The mixture was then heated to a temperature of 25°C and allowed to stand for several hours. This prepared the etching solution (microfabrication agent) for Comparative Example 19.

[0080] (Comparative Example 20) Hydrofluoric acid (manufactured by Stella Chemifa, 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 as shown in Table 5. The mixture was then heated to a temperature of 25°C and allowed to stand for several hours. This prepared the etching solution (microfabrication agent) of Comparative Example 20.

[0081]

[0082] (Wet Etching Process 1) A silicon wafer is prepared as the workpiece. The silicon wafer has a stacked body formed by sequentially depositing a silicon thermal oxide film (film thickness: 10 nm) and a polycrystalline silicon film (film thickness: 90 nm) on its surface. The stacked body is arranged in a parallel manner with multiple trenches (length: 6 mm, width: 250 nm, depth: 100 nm) spaced 250 nm apart (Global Net (share), diameter: 8 inches, see Figure 2(a)). The silicon wafer is cut into square test piece dimensions (length: 2 cm, width: 2 cm), and then a batch wet etching process is performed using the etching solutions of the aforementioned embodiments and comparative examples. The wet etching process involves immersing the silicon wafer in etching tanks filled with different etching solutions to etch the silicon thermal oxide film, directly exposing the surface of the silicon wafer to the etching solution. The etching time was 3 minutes in Examples 1-4, 8-10, 12-14, and 16-50, and Comparative Examples 2 and 20; 30 seconds in Examples 5-7 and 11, and Comparative Examples 3-7; and 10 minutes in Example 15, and Comparative Examples 1, 11-15, and 18-19. The temperature of the etching solution was set to 25°C. The silicon wafer was then removed from the etching tank and immersed in a rinsing tank overflowing with ultrapure water for 5 minutes. Afterward, the silicon wafer was removed from the rinsing tank and allowed to dry.

[0083] Next, for the test pieces that have undergone wet etching treatment 1, the cross-section of the laminate was observed using a scanning electron microscope (JEOL Ltd., JSM-7800F), and the amount of etching of the silicon thermal oxide film after wet etching treatment was measured. For each etching solution of Examples 1 to 50 and Comparative Examples 1 to 7, 11 to 15, 18 to 20, the etching rate V1 (nm / min) at an etching temperature (liquid temperature of the etching solution) of 25°C was calculated. The results are shown in Tables 6 to 10. Furthermore, regarding the etching solutions of Comparative Examples 8 to 10, 16 and 17, since the polycrystalline silicon film was also etched in addition to the silicon thermal oxide film, the narrow area was also expanded in the vertical direction relative to the silicon wafer surface, making it difficult to measure the etching rate V1.

[0084] (Wet Etching Process 2) A silicon wafer (manufactured by Global Net, diameter: 8 inches) with a silicon thermal oxide film (film thickness: 10 nm) formed on its surface, was prepared as another workpiece. The wafer was subjected to batch wet etching using the etching solutions of the aforementioned embodiments and comparative examples. The wet etching process involved immersing the silicon wafer in etching tanks filled with different etching solutions, adjusting the etching time appropriately so that a specified 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 tank and immersed in a rinsing tank overflowing with ultrapure water for 5 minutes. Afterward, the silicon wafer was removed from the rinsing tank and dried.

[0085] Next, the film thickness of the silicon thermal oxide film before and after wet etching was measured using an optical film thickness measuring device (manufactured by Onto Innovation Inc., NanospecII), and the change in film thickness caused by etching was also measured. For each etching solution of Examples 1-50 and Comparative Examples 1-7, 11-15, and 18-20, the etching rate V2 (nm / min) at an etching temperature (liquid temperature of the etching solution) of 25°C was calculated. The results are shown in Tables 6-10.

[0086] (Evaluation of etching in narrow areas) Regarding the etching solutions of the aforementioned embodiments and comparative examples, the etching performance in narrow areas was evaluated based on the results of wet etching treatment 1 and wet etching treatment 2. Specifically, firstly, the etching rate ratio (V1 / V2(-)) was calculated using the individual etching rates V1 and V2 calculated by wet etching treatment 1 and wet etching treatment 2.

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

[0088] From the results in Tables 6 to 10, it can be seen that the etching rate ratio (V1 / V2(-)) of each etching solution in Examples 1 to 50 is 0.75 or higher, and the improvement rate is also good. In particular, the improvement rate of the etching solutions in Examples 1 to 5, 8 to 18, and 21 to 50 is all 10% or higher. Thus, it can be confirmed that even in narrow areas, each etching solution in Examples 1 to 50 can still selectively etch the silicon thermal oxide film well.

[0089] On the other hand, as previously mentioned, the etchants of Comparative Examples 8-10, 16, and 17 etched the polycrystalline silicon film along with the silicon thermal oxide film, indicating that these etchants could not achieve selective etching of the silicon thermal oxide film. Furthermore, the etching rate ratios (V1 / V2(-)) of the etchants of Comparative Examples 11-15 and 18-20 were in the range of 0.67 to 0.72, which were smaller than those of the etchants of Examples 1-50, and the improvement rate was also poor. Therefore, it was confirmed that the etchants of Comparative Examples 11-15 and 18-20 did not perform well in selectively etching the silicon thermal oxide film in narrow regions.

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

[0091] First, 20 ml of each etching solution was added to a 40 ml styrene bottle. The liquid level of each etching solution was 25 mm immediately after addition. Next, the styrene bottle was shaken for 10 seconds to generate bubbles, and then allowed to stand. Next, the bubble height (from the liquid level of the etching solution to the apex of the highest bubble) was visually measured after 10 seconds and after 60 seconds of standing.

[0092] Furthermore, the time it takes for the bubbles generated by vibration to disappear (defoaming time) is measured. More specifically, the time required for a portion of the ring of bubbles adhering to the entire circumference of the inner wall of the styrene bottle to disappear after the bottle has been vibrated for 10 seconds and then left to stand (see Figure 3). The results are shown in Tables 6 to 10. Figure 3 is also a schematic plan view showing the appearance of etching solution bubbles adhering to the inner wall of the styrene bottle.

[0093] As shown in Tables 6 to 10, the etching solutions of Examples 1 to 50 all effectively suppressed foaming, and the generated bubbles were defoamed within 10 seconds of standing. On the other hand, in the etching solution of Comparative Example 7, the space inside the styrene bottle was filled with bubbles, and more bubbles were generated compared to the etching solutions of Examples 1 to 50. Furthermore, even after 300 seconds of standing, the styrene bottle could not defoam.

[0094]

[0095]

[0096]

[0097]

[0098] [Simplified Explanation of the Diagram]

[0022] [Figure 1] Figure 1(a) is a cross-sectional schematic diagram showing a silicon oxide film formed in a blanket shape on a substrate, and Figure 1(b) is a cross-sectional schematic diagram showing a silicon oxide film subjected to microprocessing using the microprocessing agent of this embodiment. [Figure 2] Figure 2(a) is a cross-sectional schematic diagram showing a substrate after silicon oxide film and polycrystalline silicon film are sequentially deposited, and Figure 1(b) is a cross-sectional schematic diagram showing a narrow area of ​​silicon oxide film subjected to microprocessing using the microprocessing agent of this embodiment. [Figure 3] A plan view schematically showing etching solution bubbles adhering to the inner wall of a styrol bottle.

Claims

1. A microprocessing agent for selectively microprocessing a workpiece having at least a silicon oxide film, comprising: (a) hydrogen fluoride in a content of 25% by mass or less relative to the total mass of the microprocessing agent; (b) at least one water-soluble polymer in a content of 1×10⁻⁴% by mass or more but less than 1% by mass relative to the total mass of the microprocessing agent, having a mass average molecular weight of 600 to 15,000; and (c) water; wherein the water-soluble polymer comprises building units having primary and / or secondary amine groups.

2. The microprocessing agent of claim 1, further comprising (d) a compound having a content of more than 1 × 10⁻⁴ % by mass and less than 1 % by mass relative to the total mass of the aforementioned microprocessing agent, and having at least one relative ion selected from the group consisting of Cl⁻, Br⁻, CH₃COO⁻, HSO₄⁻, SO₄²⁻, NO₃⁻, H₂PO₄⁻, HPO₄²⁻ and PO₄³⁻.

3. The microprocessing agent as claimed in claim 1, wherein the aforementioned structural unit is any one of the following chemical formulas (1) to (4); 4. The microprocessing agent as claimed in claim 2, wherein the aforementioned compound having a relative ion is an ammonium salt, potassium salt, or carboxylic acid.

5. The microprocessing agent as claimed in claim 4, wherein the aforementioned ammonium salt is selected from at least one of the group consisting of ammonium chloride, ammonium bromide, ammonium acetate, ammonium sulfate, ammonium nitrate, diammonium hydrogen phosphate and triammonium phosphate.

6. The microprocessing agent as claimed in claim 4, wherein the aforementioned potassium salt is potassium acetate.

7. The microprocessing agent as claimed in claim 4, wherein the aforementioned carboxylic acid is acetic acid.

8. The microprocessing agent as described in claim 1, wherein the agent does not contain surfactants.

9. A microfabrication method comprising using the microfabrication agent described in any one of claims 1 to 8 to selectively microfabricate the silicon oxide film on the aforementioned subject having at least a silicon oxide film.

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