Manufacturing method for a member having a recessed structure

Abstract

To provide a manufacturing method that enables the precise and rapid production of a component having a recessed structure that closely resembles a vertical structure. [Solution] A manufacturing method according to one embodiment of the present invention is a method for manufacturing a member having a recessed structure, comprising: a first step of preparing a workpiece containing an element whose fluoride boiling point is 550°C or lower; a second step of forming a catalyst material on a part of the surface of the workpiece; and a third step of exposing the workpiece to an etching gas in an environment of 80°C or higher to form a recessed structure on the portion of the workpiece where the catalyst material has been formed, wherein the etching gas includes a fluorine-containing gas and an acidic gas, and the acidic gas has a lower acid dissociation constant than hydrogen fluoride.

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a member having a recessed structure. [Background technology]

[0002] Microfabrication technology, which can form fine recessed structures on the surface of a sample, is in demand in various fields. To date, various methods have been proposed and put into practical use as microfabrication technologies.

[0003] One microfabrication technique is dry etching, in which the surface of a sample is etched using reactive gases, ions, and / or radicals.

[0004] For example, in reactive ion etching (RIE) methods, such as inductive coupled plasma-RIE (ICP-RIE), etching is performed by plasmaizing an etching gas and colliding it with the sample. Such RIE methods have been reported to enable extremely fine processing of samples (for example, Non-Patent Document 1). [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] xiao Li,King Yuk Chan and Rodica Ramer,“Fabrication of Through via Holes in Ultra-Thin Fused SilicaWafers for Microwave and Millimeter-Wave Applications”,micromachines,2018,9,138 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, with the RIE method, when forming recessed structures on the surface of a sample, tapered shapes tend to form on the side walls, making it difficult to form recessed structures close to the ideal shape (vertical structure). Furthermore, there is a need to form members with recessed structures close to a vertical structure with high precision and in a short amount of time.

[0007] This invention has been made in view of the above background, and aims to provide a manufacturing method that enables the accurate and rapid production of a member having a recessed structure close to a vertical structure. [Means for solving the problem]

[0008] The present invention provides a method for manufacturing a member having a recessed structure, A method for manufacturing a member having a recessed structure, The first step is to prepare a material to be treated that contains elements whose fluoride boiling point is 550°C or lower, A second step involves forming a catalyst material on a part of the surface of the object to be treated, The process includes a third step of exposing the workpiece to an etching gas in an environment of 80°C or higher to form a recessed structure in the portion of the workpiece where the catalyst material is formed, The etching gas includes a fluorine-containing gas and an acidic gas. The method is provided in which the acidic gas has a lower acid dissociation constant than hydrogen fluoride. [Effects of the Invention]

[0009] The present invention provides a method for relatively easily manufacturing a member having a recessed structure that is close to a vertical structure. Furthermore, the present invention can provide a member having such a recessed structure. [Brief explanation of the drawing]

[0010] [Figure 1] This diagram schematically illustrates the reaction mechanism that can occur on the surface of a treated object when the organic compound does not have polar functional groups. [Figure 2]The figure schematically shows a reaction mechanism that can occur on the surface of the object to be treated when the organic compound has a polar functional group. [Figure 3] The figure schematically shows a reaction mechanism that can occur on the surface of the object to be treated when the organic compound has another polar functional group. [Figure 4] The figure schematically shows the optimized three-dimensional structure of molecule X obtained by the ETKDG method and the atoms with negative Gasteiger charges. [Figure 5] The figure schematically shows the three-dimensional structure of the structure obtained by adding hydrogen atoms to molecule X, which was obtained by the ETKDG method. [Figure 6] The figure schematically shows the state of adding a fluorine atom to molecule Y to form a composite compound. [Figure 7] The figure schematically shows the structure of molecule Z optimized by DFT calculation. [Figure 8] The figure shows the relationship between the processing temperature and the etching reaction rate during the hydrogen fluoride (HF) gas etching of glass. [Figure 9] The cross-sectional view schematically shows a process of the process according to an embodiment of the present invention. [Figure 10] The cross-sectional view schematically shows a process of the process according to an embodiment of the present invention. [Figure 11] The figure schematically shows the flow of a method for manufacturing a member having a concave structure according to an embodiment of the present invention. [Figure 12] In the method for manufacturing a member having a concave structure according to an embodiment of the present invention, the perspective view schematically shows the state where a catalyst material is installed on the object to be treated. [Figure 13] In the method for manufacturing a member having a concave structure according to an embodiment of the present invention, the cross-sectional view schematically shows an example of the object to be treated 110 after the etching process. [Figure 14] The perspective view shows a member according to an embodiment of the present invention. [Figure 15] The schematic cross-sectional view is taken along line A-A of the member according to an embodiment of the present invention shown in FIG. 14. [Figure 16] It is a diagram schematically showing the form of the surface of the side wall of the recessed structure in the member according to an embodiment of the present invention. [Figure 17] It is a schematic diagram for explaining the taper angle θ of the recessed structure. [Figure 18] It is a photograph showing an example of the cross section of the recessed structure according to an embodiment of the present invention. [Figure 19] It is a photograph showing an example of the cross section of the recessed structure according to another embodiment of the present invention. [Figure 20] It is a graph showing the relationship between the HCl addition amount and the etching rate.

Mode for Carrying Out the Invention

[0011] Hereinafter, an embodiment of the present invention will be described.

[0012] As described above, there is a problem that it is difficult to accurately form a recessed structure close to a vertical structure on the surface of a sample in a short time. Here, the "recessed structure close to vertical" means a structure in which there is no or a small "taper shape" on the side wall of the recessed structure.

[0013] Also, the "taper shape" means a form in which the side wall partitioning the recessed structure is inclined with respect to the extension axis in the depth direction of the recessed structure.

[0014] In order to address such conventional problems, the inventors of the present application have conducted intensive research and development and found a microfabrication technology capable of accurately forming a recessed structure close to a vertical structure in a short time.

[0015] That is, in one embodiment of the present invention, a first step of preparing a workpiece containing an element whose fluoride has a boiling point of 550°C or lower; [[ID=!44]]a second step of forming a catalyst material on a part of the surface of the workpiece; and a third step of exposing the workpiece to an etching gas in an environment of 80°C or higher to form a recessed structure in the portion of the workpiece where the catalyst material is formed. The etching gas includes a fluorine-containing gas and an acidic gas. The aforementioned acidic gas has a lower acid dissociation constant than hydrogen fluoride. A method for manufacturing a member having a recessed structure is provided.

[0016] A method according to one embodiment of the present invention includes a process of exposing a workpiece on which a catalyst material is formed on its surface to an etching gas at a processing temperature of 80°C or higher (hereinafter, this process will be referred to as the "etching process of the present invention"). By carrying out such an etching process of the present invention, the method according to one embodiment of the present invention can selectively etch the region on the surface of the workpiece where the catalyst material is formed (hereinafter, referred to as the "coated region") at a relatively fast rate.

[0017] The following explanation, with reference to the drawings, will describe the reasons why such etching is possible as currently understood.

[0018] First, we will explain the role of the catalyst material and the effect of the processing temperature in the etching process of the present invention.

[0019] (Role of catalytic materials) In the etching process of the present invention, the catalyst material comprises an organic compound having a polar functional group. Such an organic compound having a polar functional group is thought to play a role in lowering the activation energy of fluoride formation on the surface of the workpiece.

[0020] The role of this process will be explained below using Figures 1 to 3. Figures 1 to 3 schematically show the reaction on the surface of the object being treated where the catalyst material is placed.

[0021] For the purposes of the following explanation, we will assume that the material to be treated is SiO2 and that its surface is hydrogen-terminated.

[0022] First, Figure 1 schematically shows the expected etching mechanism on the surface of the object to be treated when the organic compound does not have polar functional groups.

[0023] When an etching gas containing hydrogen fluoride (HF) gas and hydrogen chloride (HCl) gas is supplied from the environment to the area on the surface of the SiO2 to be treated where the catalyst material is installed, i.e., the "coated area", the HF molecules (a) perform a nucleophilic attack on the Si atoms (b), as shown in (i).

[0024] However, for the Si atom (b) to react with the F atom on the surface of the material being treated, the OH group (c) on the surface must interact with the H atom of the HF molecule (a), as shown in (ii), to weaken the HF bond. In other words, unless enough energy is provided to break the HF bond in the HF molecule (a), the Si-F bond (d) accompanied by the elimination of H2O (g), as shown in (iii), will not form.

[0025] However, in this reaction system, there are no substances that contribute to the decrease in the activation energy of the Si-F bond (d). Therefore, no significant etching reaction proceeds in the coated region.

[0026] In this system, as with conventional mask pattern processing, the etching rate tends to be higher in areas where the workpiece is in direct contact with the HF gas, i.e., in areas where no catalyst material is installed on the surface (hereinafter referred to as the "uncoated area").

[0027] On the other hand, Figure 2 schematically shows the reaction mechanism on the surface of the treated object when the organic compound has a polar functional group. Here, a hydroxyl group is assumed to be the polar functional group.

[0028] In this case as well, if an etching gas containing HF gas and HCl gas is supplied from the environment to the coated region of the catalyst material, the HF molecule (a) will perform a nucleophilic attack on the Si atom (b), as shown in (i).

[0029] However, in this case, in addition to the above, the oxygen atom of the -δ part (e) of the polar functional group interacts with the hydrogen atom of the HF molecule (a). Also, the hydrogen atom of the +δ part (f) of the polar functional group interacts with the surface OH group (c).

[0030] Therefore, as shown in (ii), the HF bond in HF molecule (a) is weakened. The Si(b)-OH(c) bond is also weakened. This lowers the activation energy required for the bonding reaction between the Si atom and the F atom.

[0031] As a result, as shown in (iii), the O atom of the -δ part (e) of the polar functional group removes the H atom from the HF molecule (a), and the H atom of the +δ part (f) reacts with the OH group on the surface, resulting in the elimination of H2O (g).

[0032] This causes the Si atom (b) to bond with the fluorine atom. Finally, SiF4 and H2O are formed by the following reaction equation (1). SiO2+4HF → SiF4↑+ 2H2O↑ (1) Both SiF4 and H2O produced in the reaction are gases at the processing temperature and are quickly released from the system.

[0033] Through the reaction mechanism described above, the area directly beneath the coating region of the catalyst material is selectively etched in the object being treated.

[0034] In the above example, an etching gas containing HCl gas is supplied. HCl gas is a strong acid and decomposes the surface of organic compounds. Therefore, when an etching gas containing HCl gas is supplied, the amount of OH groups (c) on the surface increases. Then, the H atoms of the +δ (f) portion of more polar functional groups interact with the OH groups (c), i.e., the catalytic effect is increased.

[0035] Furthermore, the above reactions and the increase in catalytic effect are not limited to cases where the polar functional group contains a hydroxyl group. For example, similar reactions can occur when the polar functional group has at least one of the following: an aldehyde group, a carboxyl group, an amino group, a sulfo group, a thiol group, and an amide bond.

[0036] Furthermore, Figure 2 illustrates the reaction mechanism using the case where the polar functional group of an organic compound contains a hydrogen atom as an example. However, the polar functional groups of organic compounds are not necessarily limited to those containing a hydrogen atom.

[0037] Figure 3 schematically shows the reaction mechanism when an organic compound has another polar functional group. Here, a carbonyl group (>C=O) without a hydrogen atom is assumed as the polar functional group.

[0038] In this example as well, when HF gas is supplied from the environment to the coated region of the catalyst material, the HF molecule (a) performs a nucleophilic attack on the Si atom (b), as shown in (i). In addition, the O atom of the -δ part (e) of the polar functional group interacts with the H atom of the HF molecule (a).

[0039] As a result, the HF bond of HF molecule (a) is weakened, as shown in (ii).

[0040] Next, as shown in (iii), the H atom that was detached from the HF molecule (a) by the O atom of the -δ part (e) of the polar functional group combines with the OH group (c) to produce H2O (g).

[0041] Thus, in this case as well, the activation energy required for the bonding reaction between Si atoms and F atoms decreases. As a result, the reaction shown in reaction equation (1) above occurs, and the area directly beneath the coated region of the object being treated is selectively etched.

[0042] Similar reaction mechanisms can also occur, for example, when the polar functional group has at least one of a nitro group, a cyano group, an ether bond, and an ester bond.

[0043] Thus, in the etching process of the present invention, the presence of an organic compound having a polar functional group contained in the catalyst material promotes the fluoride formation reaction in the coated region of the workpiece, allowing for selective etching of the area directly beneath the coated region.

[0044] Furthermore, the etching process of the present invention may include an organic molecule as a substructure, which, as a catalyst material, has a value of 0.965 (Å) or greater for the distance dHF between a hydrogen atom and a fluorine atom in a hydrogen fluoride molecule, assuming an adsorption structure with an SiO2 surface, calculated using the 6-31+G(d) basis function and the B3LYP correlation-exchange functional.

[0045] Here, dHF is calculated using the following method.

[0046] (How to calculate dHF) First, the structural information of the target organic molecule (hereinafter referred to as "molecule X") is obtained from SMILES using the RDKit library, and a 3D structure is generated using the ETKDG method. The version of RDKit used is 2023.9.4, developed by GitHub and SourceForge, executed in Python 3.10.13, and obtained as open source, with the open-source version being released in June 2006.

[0047] Next, we calculate the Gasteiger charge and identify the atoms with a negative Gasteiger charge (hereinafter referred to as "site atoms P").

[0048] Figure 4 schematically shows, as an example, the optimized structure of molecule X obtained by the above method and the site atom P assigned to molecule X. In this example, molecule X has the general formula primary amine, and there is only one site atom P. In Figure 4, the large gray spheres represent carbon atoms, the black spheres represent nitrogen atoms, and the smallest white spheres represent hydrogen atoms.

[0049] Next, the following procedure is used to add an H atom to molecule X to form a conjugate acid compound (hereinafter referred to as "compound Y"), and to generate the three-dimensional coordinates of compound Y.

[0050] First, a formal charge of 1 is added to the site atom P, and a hydrogen atom is bonded to the site atom.

[0051] Next, the structure is optimized using the ETKDG method to generate the three-dimensional structure of the conjugate acid.

[0052] Figure 5 shows a simulated three-dimensional structure of compound Y, along with site atom P and the added hydrogen atom H. The three-dimensional structure of compound Y thus generated is converted into an SDF file to obtain its three-dimensional coordinates.

[0053] Next, a fluorine atom is positioned 1.0 Å away from the hydrogen atom to which a bond has been added to site atom P, thereby forming a composite compound (hereinafter referred to as "compound Z"), and a three-dimensional structure is generated by the ETKDG method.

[0054] In this case, the site atom P, the hydrogen atom, and the fluorine atom must be arranged in a straight line.

[0055] Figure 6 shows the three-dimensional structure of compound Z, along with a simulated representation of the site atom P, the hydrogen atom H, and the fluorine atom F. The dashed arrows indicate the straight lines they share.

[0056] The three-dimensional structure of compound Z generated by the above procedure is used as the initial structure, and structural optimization is performed using DFT calculations. Figure 7 shows the structure of compound Z after structural optimization by DFT calculations.

[0057] From the obtained optimized structure, the distance dHF between the fluorine atom and the hydrogen atom in the added hydrogen fluoride molecule is calculated.

[0058] If the target compound has multiple site atoms, each atom is treated as a site atom, and the above procedure is repeated until the distance between the fluorine atom and the hydrogen atom in the largest hydrogen fluoride molecule is determined as dHF.

[0059] All DFT calculations are preferably performed using the Gaussian package, and structural optimization is performed using the DFT method, 6-31+G(d) basis functions, B3LYP correlation-exchange functional, default spin, ±0 charge, and singlet state. The version of Gaussian used is Gaussian16, developed by Carnegie Mellon University, available through a paid license agreement, and first released in 1970.

[0060] Here, for atomic species with atomic numbers greater than Kr, we use LanL2DZ as the basis set.

[0061] Similarly, dHF can be calculated for other basis functions and correlation-exchange functionals other than the 6-31+g(d) basis function and the B3LYP correlation-exchange functional.

[0062] The basis set requirements include having outer shell orbitals at or above the DZ level or TZ level, with the diffuse function added.

[0063] Although the absolute value of dHF defined in this invention does not match the calculated values ​​for other basis functions and correlation-exchange functionals, the trends match with good accuracy.

[0064] Specific examples of substructures of organic molecules with a dHF value of 0.965 (Å) or higher include structures containing an amino group, phosphorus, and at least one ring structure containing at least one of nitrogen and oxygen.

[0065] When an organic compound having the above-mentioned functional group is used, electron donation occurs from the organic compound to the antibonding orbital of HF, increasing the bond length between HF atoms. This is expected to increase the basicity of F and its nucleophilicity to nearby Si atoms, thus increasing reactivity.

[0066] Examples of organic compounds having a phosphorus-containing structure include the following compounds.

[0067] [ka]

[0068] Examples of organic compounds having a ring structure containing at least one of nitrogen and oxygen include the following compounds.

[0069] [ka]

[0070] Furthermore, the following compounds are examples of organic compounds that contain an amino group.

[0071] [ka]

[0072] Furthermore, the organic compound having a functional group contained in the organic catalyst material according to one embodiment of the present invention does not necessarily have to be just one type, but may be used in a mixture of two or more types.

[0073] An organic catalyst material according to one embodiment of the present invention has crosslinking properties. Here, "having crosslinking properties (organic compound)" means that when light or heat is applied to the material in question, a crosslinked material is formed from the material.

[0074] In one embodiment of the present invention, the material may be one that exhibits crosslinking properties on its own (hereinafter referred to as a "crosslinkable organic molecule") or one that does not exhibit crosslinking properties on its own (hereinafter referred to as a "non-crosslinkable organic molecule"). In the latter case, the organic catalyst material according to one embodiment of the present invention further comprises a crosslinking agent.

[0075] However, even in the former case, the organic catalyst material according to one embodiment of the present invention may further contain a crosslinking agent. In this case, the presence of the crosslinking agent accelerates the conversion from crosslinkable organic molecules to crosslinked products.

[0076] An organic catalyst material according to one embodiment of the present invention may have other additives in addition to, or separately from, the crosslinking agent.

[0077] (Crosslinking agent) As described above, the organic catalyst material according to one embodiment of the present invention may contain a crosslinking agent.

[0078] Crosslinking agents are not limited to these, but include, for example, TADT (N,N',N''-triacryloydiethylenetriamine) (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), MT3041 (manufactured by Toagosei Co., Ltd.), EX512 (manufactured by Nagase ChemteX Corporation), and PETA (Pentaerythritol triacrylate; manufactured by Shin Nakamura Chemical Co., Ltd.).

[0079] TADT and PETA are represented by the following structural formulas (11) and (12), respectively.

[0080] [ka] The amount of crosslinking agent added is not particularly limited. For example, the crosslinking agent may be added in an amount ranging from 0 mol% to 90 mol% of the total amount of the organic compound having the aforementioned polar functional group and the crosslinking agent.

[0081] (Additives) The organic material according to one embodiment of the present invention may contain various additives.

[0082] The additives are not limited to these, but may include, for example, photoradical initiators, photoacid generators, photobase generators, thermal acid generators, or thermal base generators.

[0083] The amount of additive added may be, for example, in the range of 0.1 mol% to 20 mol% relative to the total amount of the organic material according to one embodiment of the present invention, and preferably in the range of 0.1 mol% to 5 mol%.

[0084] (Effect of processing temperature) Next, we will explain the effect of processing temperature.

[0085] In the etching process of the present invention, the processing temperature is 80°C or higher. This is because, below 80°C, proper etching selectivity does not occur between the coated and uncoated areas on the surface of the workpiece.

[0086] The effects of processing temperature will be explained in more detail below, with reference to Figure 8.

[0087] Figure 8 shows the relationship between processing temperature and etching reaction rate during hydrogen fluoride (HF) gas etching of glass, as obtained by the inventors of the present invention.

[0088] Figure 8 shows that the etching rate of glass gradually increases with temperature up to 80°C. However, above 80°C, the etching rate decreases sharply. As a result, the etching rate peaks at temperatures below 80°C.

[0089] This phenomenon is thought to correspond to the associated / unassociated states of HF gas. Specifically, HF gas is in an associated state below 80°C, but becomes unassociated (elementary) above 80°C. Furthermore, when HF gas is in an associated state, the bonding force of the HF bond is relatively weaker when viewed as a single molecule. Consequently, the fluorine atoms of the HF molecule become more likely to bond with the surface of the material being treated, making it easier to form fluorides. This behavior is thought to be the reason why high etching rates can be obtained below 80°C.

[0090] In the etching process of the present invention, if the processing temperature is set below 80°C, the effects of the association state of HF gas will occur, and the workpiece will be etched in the uncoated region of the catalyst material. Consequently, the etching selectivity in the coated region due to the aforementioned reaction mechanism will decrease.

[0091] In contrast, when the processing temperature is set to 80°C or higher, the high etching force due to the associated HF gas can be suppressed in the uncoated region of the catalyst material. Furthermore, based on the reaction mechanism described above, etching of the workpiece becomes possible directly beneath the coated region. As a result, the etching process of the present invention (processing temperature of 80°C or higher) can achieve high etching selectivity between the coated and uncoated regions of the catalyst material. Moreover, this allows for selective etching of the coated region in the etching process of the present invention.

[0092] (The recessed structure that is formed) In conventional RIE methods, a "tapered shape" tends to form on the side walls of recessed structures, making it difficult to create recessed structures that are close to vertical structures.

[0093] In contrast, the etching process of the present invention makes it relatively easy to form a recessed structure (hereinafter referred to as a "vertical recessed structure") that does not have a "tapered shape" and has side walls that extend substantially parallel to the extension axis in the depth direction.

[0094] The reason for this will be explained below with reference to Figures 9 and 10.

[0095] Figures 9 and 10 schematically illustrate one step of the etching process of the present invention.

[0096] Figure 9 schematically shows the state in which the catalyst material 3 is placed on the surface of the object to be treated 1. Note that in Figures 9 and 10, for illustrative purposes, the object to be treated 1 and the catalyst material 3 are shown to be separated from each other, but in reality, they are in contact.

[0097] As mentioned above, it is assumed that the object to be treated 1 is SiO2 and that its surface is H-terminated.

[0098] The catalyst material 3 is an organic compound having a polar functional group, and here, an OH group is assumed to be the polar functional group. By placing the catalyst material 3 on the surface of the object to be treated 1, a coated region 8a and an uncoated region 8b are formed on the object to be treated 1.

[0099] As described above, by exposing the workpiece 1, heated to 80°C or higher, to an etching gas containing HF gas and HCl gas, selective etching proceeds directly beneath the coated region 8a where the catalyst material 3 is installed. As a result, a recessed structure is formed directly beneath the coated region 8a. Note that the size of the HF molecules is sufficiently smaller than the size of the voids within the catalyst material 3. Therefore, when the workpiece 1 is exposed to HF gas, the HF gas can pass through the catalyst material 3 and reach the interface between the catalyst material 3 and the workpiece 1.

[0100] Figure 10 shows a state in which etching of the workpiece 1 has progressed to a certain extent, and a recessed structure 5 of a certain depth has been formed.

[0101] As mentioned above, catalyst material 3 is placed in the coated region 8a. Therefore, even as the etching reaction proceeds, catalyst material 3 remains on the bottom surface 6 of the recessed structure 5. In other words, as long as the etching process continues, the bottom surface 6 of the recessed structure 5 remains in contact with catalyst material 3. As a result, the bottom surface 6 of the recessed structure 5 continues to be etched by the reaction mechanism described above, and the etching of the bottom surface 6 continues in the depth direction.

[0102] On the other hand, focusing on the side wall 7 of the recessed structure 5, once etching begins, the etching reaction proceeds in the portion of the side wall 7 that is in contact with the catalyst material 3, according to the mechanism described above. More precisely, only the portion of the workpiece 1 that is in contact with the side surface of the catalyst material 3 is etched. As a result, the recessed structure 5, partitioned by the side wall 7, is formed in the portion that is in contact with the side surface of the catalyst material 3.

[0103] However, as the catalyst material 3 continues to descend deeper, beyond a certain point, the upper part of the side wall 7 no longer comes into contact with the side surface of the catalyst material 3. Hereinafter, this side wall 7 that is no longer in contact with the side surface of the catalyst material 3 will be referred to as the "first side wall portion 7a".

[0104] As mentioned above, in areas where the catalyst material 3 is not present, such as the uncoated region 8b, etching does not substantially proceed. In other words, in the workpiece 1, the etching reaction occurs only when it is in contact with the catalyst material 3, and does not occur in any other state. For this reason, in the sidewall 7, in areas that have lost contact with the catalyst material 3, such as the first sidewall portion 7a, the etching process effectively stops thereafter.

[0105] This is a crucial difference from conventional dry etching methods such as the RIE method. In the RIE method, even areas where etching is already complete, such as near openings on the surface of the workpiece, continue to be exposed to the reaction gas during the etching process. Therefore, the continuation of the etching process increases the likelihood of the formation of recessed structures with a tapered shape.

[0106] In the etching process of the present invention, as a result of the etching stopping action at the first side wall portion 7a that does not come into contact with the catalyst material 3, etching of the workpiece 1 selectively proceeds only directly beneath the catalyst material 3, ultimately forming a vertical recess structure.

[0107] Due to the effects described above, the etching process of the present invention makes it possible to form a characteristic vertical recess structure as the recess structure 5.

[0108] The etching process of the present invention further has the following additional effects: (I) It is possible to form deep recessed structures. In the conventional RIE method, SiO x There is a limit to the etching depth; for example, when using photoresist as a masking agent, it is difficult to form deep recessed structures such as 20 μm deep.

[0109] However, in the etching process of the present invention, the etching reaction proceeds as long as the etching gas is continuously supplied to the coated area. Therefore, it is possible to form recessed structures with a high aspect ratio. For example, aspect ratios of 10 or more can be achieved.

[0110] Note that "aspect ratio" refers to the depth dimension relative to the minimum dimension of the opening in a recessed structure. (II) Rapid etching is possible The RIE method using etching gases that do not contain acidic gases such as hydrogen chloride gas resulted in a processing speed of 0.65 μm / min or less.

[0111] In contrast, the etching process of the present invention can increase the processing speed (etching speed) in the depth direction of the recessed structure by more than 1.5 times, for example, due to the catalytic enhancement effect of an acidic gas such as hydrogen chloride gas. Therefore, the etching process of the present invention can be used as a rapid recessed structure formation technology.

[0112] (Method for manufacturing a member having a recessed structure according to one embodiment of the present invention) Next, with reference to Figures 11 to 13, a method for manufacturing a member having a recessed structure according to one embodiment of the present invention will be described in more detail.

[0113] Figure 11 schematically shows a flow chart of a method for manufacturing a member having a recessed structure according to one embodiment of the present invention.

[0114] As shown in Figure 11, the method for manufacturing a member having a recessed structure according to the present invention (hereinafter also referred to as "the manufacturing method according to the present invention") is as follows: The first step (S110) is to prepare a workpiece containing an element whose fluoride boiling point is 550°C or lower, The second step (S120) is to form a catalyst material on a part of the surface of the object to be treated, The process includes a third step (S130) of exposing the workpiece to an etching gas in an environment of 80°C or higher to form a recessed structure in the portion of the workpiece where the catalyst material is formed, The etching gas includes a fluorine-containing gas and an acidic gas. The aforementioned acidic gas has a lower acid dissociation constant than hydrogen fluoride.

[0115] The following explains each step.

[0116] (Step S110) First, the object to be processed is prepared.

[0117] The object to be processed may be composed of a single component or multiple components.

[0118] When the object to be treated is composed of a single component, the object to be treated is composed of an element that, upon reaction with fluorine (F), forms a fluoride with a boiling point of 550°C or lower.

[0119] For example, the material to be treated may contain at least one element selected from the group consisting of B, C, Si, P, S, Ti, V, Cr, Ga, Ge, As, Se, Nb, Mo, Tc, Ru, Rh, Sn, Sb, Te, I, Ta, W, Re, Os, Ir, Pt, and Au. Furthermore, the material to be treated may also contain at least one element selected from the group consisting of H, N, Cl, Br, and O.

[0120] In particular, it is preferable that the material to be treated is composed of an element that, upon reaction with fluorine, forms a fluoride with a boiling point of 200°C or lower.

[0121] For example, silicon (Si) has a boiling point of -86°C as fluoride SiF4, and a material containing silicon can be suitably used as a material to be treated in the manufacturing method according to the present invention.

[0122] Furthermore, the boiling points of the fluorides (AlF3) and (CaF2), respectively, of Al and Ca exceed 550°C. Therefore, Al and Ca cannot be said to be elements that form fluorides with a boiling point below 550°C through reaction with fluorine (F).

[0123] The material to be processed may be, for example, a quartz glass substrate, a crystal substrate, or a silicon substrate.

[0124] On the other hand, if the object to be treated is composed of a laminate of multiple components, the object to be treated contains an element whose fluoride boiling point is 550°C or lower on its outermost surface.

[0125] As mentioned above, such elements may be selected from the group consisting of, for example, B, C, Si, P, S, Ti, V, Cr, Ga, Ge, As, Se, Nb, Mo, Tc, Ru, Rh, Sn, Sb, Te, I, Ta, W, Re, Os, Ir, Pt, and Au. The first surface may also further contain at least one element selected from the group consisting of H, N, Cl, Br, and O.

[0126] For example, the object to be processed may have one or more films placed on a substrate, and the outermost film may satisfy the aforementioned characteristics. Alternatively, the entire group of films may satisfy the aforementioned characteristics.

[0127] Such films include, for example, one or more selected from the group consisting of oxides, carbides, and nitrides of Si. Such films include, for example, SiO x SiN y It may have at least one of SiCN, SiON, and SiC.

[0128] Alternatively, the substrate, along with the film, may also have the aforementioned characteristics. In this case, the manufacturing method according to the present invention can produce a component in which a recessed structure is formed even inside the substrate. The substrate may be, for example, a quartz glass substrate, a crystal substrate, or a silicon substrate.

[0129] For the sake of simplicity, in the following explanation, we will assume that the object to be treated is composed of a single piece of quartz glass, and that a recessed structure is formed on the surface of the quartz glass.

[0130] (Step S120) Next, a catalyst material is formed on a portion of the surface of the object to be treated. The catalyst material is placed in a predetermined area on the surface.

[0131] The catalyst material includes an organic compound having a polar functional group. The polar functional group may include at least one selected from the group consisting of, for example, a hydroxyl group, an aldehyde group, a carboxyl group, an amino group, a sulfo group, a thiol group, an amide bond, a carbonyl group, a nitro group, a cyano group, an ether bond, and an ester bond. The catalyst material may also be an organic compound having a phosphorus-containing structure and at least one ring structure containing at least one of nitrogen and oxygen.

[0132] Typical examples of such organic compounds include phenolic resins, acrylic resins, and methacrylic resins.

[0133] The catalyst material may consist solely of organic compounds having the aforementioned polar functional groups, or it may be provided as a mixture with other additives.

[0134] In the latter case, the catalyst material may include a solvent, a binder, and / or fine particles, etc.

[0135] There are no particular restrictions on the method of installing the catalyst material.

[0136] The catalyst material may be applied to the surface of the object to be treated by methods such as coating, printing, spin coating, or spraying.

[0137] Figure 12 schematically shows how the catalyst material is installed on the object to be treated.

[0138] As shown in Figure 12, the object to be treated 110 has a front surface 112 and a back surface 114. The catalyst material 130 is placed on a portion of the front surface 112 of the object to be treated 110.

[0139] In the example shown in Figure 12, the catalyst material 130 is arranged as a plurality of parallel linear patterns 131. However, this is merely one example, and the catalyst material 130 may be arranged in any manner depending on the required recessed structure. The catalyst material 130 may be arranged, for example, as a single straight line. Alternatively, the catalyst material 130 may be arranged, for example, as a pattern of circular dots, or as a single circular dot.

[0140] The thickness of the catalyst material 130 is not particularly limited, but may be in the range of, for example, 0.01 μm to 10 μm. According to the definition above, on the surface 112, the area on which the catalyst material 130 is installed is referred to as the coated area 140a, and the other areas are referred to as the uncoated area 140b.

[0141] (Step S130) Next, the workpiece 110 is exposed to etching gas in an environment of 80°C or higher to form recessed structures in the portions of the workpiece 110 where the catalyst material 130 is formed. Specifically, the workpiece 110 with the catalyst material 130 installed is placed inside a processing chamber. Subsequently, the processing chamber is heated to a predetermined temperature and etching gas is supplied for etching the workpiece.

[0142] The etching gas includes a fluorine-containing gas and an acidic gas. The fluorine-containing gas may be one or more selected from hydrogen fluoride gas and fluorine gas. The acidic gas is a gas with a lower acid dissociation constant than hydrogen fluoride. The acidic gas may be one or more selected from hydrogen chloride gas, hydrogen bromide gas, sulfur dioxide gas, sulfur trioxide gas, hydrogen iodide gas, and chlorine dioxide gas. The ratio of the acidic gas to the fluorine-containing gas may be in the range of 1 vol% or more. The acidic gas may be produced by reacting with water produced by the reaction of the fluorine-containing gas with the material to be treated. For example, silicon tetrachloride gas produces hydrogen chloride gas when it reacts with water. Therefore, hydrogen chloride gas produced by the reaction of the fluorine-containing gas with the material to be treated can increase the catalytic function. Examples of gases that react with water to produce acidic gases include silicon tetrachloride gas, titanium tetrachloride gas, tin tetrachloride gas, boron trifluoride, boron trichloride, boron tribromide, phosphorus trifluoride, phosphorus pentafluoride, antimony pentafluoride, iodine fluoride, titanium tetrachloride, titanium tetrafluoride, and aluminum trichloride.

[0143] The etching gas may be adjusted to a predetermined concentration by an inert gas to contain fluorine-containing gas and acidic gas. The inert gas may be argon gas or nitrogen gas, etc. The ratio of fluorine-containing gas and acidic gas to the inert gas may be in the range of 0.1 vol% to 100 vol%. Furthermore, the pressure of the etching gas during the etching process (i.e., the pressure inside the chamber) is not particularly limited and may be atmospheric pressure or a reduced pressure atmosphere.

[0144] As mentioned above, the processing temperature is 80°C or higher. The actual processing temperature varies depending on the elements contained in the workpiece 110 (especially the surface 112), as well as the type and depth of the recessed structure, but is usually in the range of 200°C to 450°C, and preferably in the range of 250°C to 400°C. By setting the processing temperature to 450°C or lower, the deterioration of organic compounds contained in the catalyst material 130 can be suppressed.

[0145] As described above, etching the workpiece 110 under these conditions causes the reaction equation (1) to occur in the coated region 140a. The fluoride and water produced by the reaction escape out of the system as gas. As a result, a recessed structure is formed in the coated region 140a of the surface 112.

[0146] The recessed structure may be a bottomed structure or a through structure. The bottomed structure may be, for example, a bottomed hole and / or a bottomed groove. The through structure may be a through hole or a through groove.

[0147] Figure 13 schematically shows an example of a cross-section of the workpiece 110 after etching.

[0148] In the example shown in Figure 13, the recessed structure 150 is composed of multiple grooves, and in a top view, each groove extends parallel to the others. In this example, each groove extends from the surface 112 in the depth direction but does not reach the back surface 114, and is therefore a bottomed groove.

[0149] Furthermore, after step S130, a step may be performed to remove the catalyst material 130 remaining on the bottom surface of the recessed structure 150. For example, the catalyst material 130 may be removed by washing the workpiece 110 with an acid solution, an alkaline solution, an organic solvent, a corrosive gas, or plasma.

[0150] Through the above process, a member 100 having a recessed structure 150 on its surface 112 can be manufactured.

[0151] In this invention, the catalyst material may include one or more selected from the group consisting of metal halides, transition metals, and oxides of transition metals. Examples of metal halides include fluorides such as manganese fluoride, iron fluoride, sodium fluoride, and calcium fluoride. Examples of transition metals include niobium, silver, titanium nickel, copper, gold, cobalt, zinc, iron, and manganese. In particular, metallic manganese and metallic iron are preferred as transition metals. Examples of transition metal oxides include manganese dioxide, iron oxide, zinc oxide, copper oxide, nickel oxide, and chromium oxide.

[0152] For example, transition metals have electrons in their d orbitals and can exist in a number of valence states. Furthermore, as is evident from their frequent use as catalysts, transition metals can easily change between multiple energy states. Therefore, when a fluorinated gas comes into contact with a transition metal, it is thought that the catalytic action of the transition metal promotes the dissociation of fluorine radicals from the fluorinated gas.

[0153] When using metal halides, transition metals, or transition metal oxides as catalyst materials, the processing temperature in step S130 can be 80°C to 1000°C. In other words, when using inorganic materials as catalysts, the processing temperature can be higher than when using organic materials.

[0154] Furthermore, in this invention, an oxidizing gas such as oxygen gas may be added as an additive gas to the etching gas. For example, when etching a Si substrate, the Si substrate may be oxidized using an oxidizing gas before etching using the above method.

[0155] Furthermore, a gas that forms a deposited film may be used along with the etching gas. By including a gas that forms a deposited film in the etching gas, the etching rate on the side walls of the recessed structure can be reduced during etching, thereby improving the rectangularity of the recessed structure. Here, the gas that forms a deposited film refers to a compound that is a gas in the etching environment and deposits on the substrate to form a film. Examples of gases that form a deposited film include fluorocarbon gases, hydrofluorocarbon gases, hydrocarbon gases, halogen-containing gases, aromatic ring-containing gases, and ethers. Alternatively, the etching gas and the gas that forms a deposited film on the side walls of the recessed structure of the substrate may be supplied alternately into the chamber. For example, by performing plasma treatment while introducing a fluorocarbon gas, hydrofluorocarbon gas, etc., a deposited film can be formed on the side walls of the recessed structure of the substrate.

[0156] Furthermore, the present invention may further include a step between step S120 and step S130 in which the catalyst material is irradiated with irradiation light including deep ultraviolet (DUV) light with a wavelength of 380 nm or less (hereinafter referred to as the "DUV irradiation process"). When such a DUV irradiation process is added, it becomes possible to control the etching rate of the workpiece during the subsequent etching process. The reason why the etching rate of the workpiece can be controlled by performing the etching process after the DUV irradiation process is thought to be because the number of polar functional groups changes due to the DUV irradiation process.

[0157] In other words, when a DUV irradiation process is performed, exposure to deep ultraviolet light with a wavelength of 380 nm or less results in a crosslinking reaction within the catalyst material 3. This crosslinking reaction reduces the number of polar functional groups (e.g., C-OH groups) contained in the catalyst material 3. Therefore, during the subsequent etching process, the effect of reducing the reaction barrier in the reaction of reaction equation (1) described above is weakened, and the etching rate is thought to decrease.

[0158] Furthermore, in this case, the number of polar functional groups contained in the catalyst material 3 also changes by changing the irradiation intensity of the irradiation light, including deep ultraviolet light, and the irradiation time of the irradiation light during the DUV irradiation process. Therefore, by changing the irradiation conditions in the DUV irradiation process, the etching rate of the workpiece 1 can be controlled during the etching process.

[0159] For example, when forming relatively shallow recessed structures, the irradiation intensity of the light in the DUV irradiation process may be increased and / or the irradiation time may be extended. This significantly reduces the etching rate in the etching process and prevents over-etching of the workpiece.

[0160] Furthermore, when forming relatively deep recessed structures, the irradiation intensity of the light used in the DUV irradiation process may be reduced, and / or the irradiation time may be shortened. This increases the etching rate in the etching process and reduces the processing time.

[0161] Thus, basic etching technology allows for the manufacture of components with vertical recess structures at various etching rates.

[0162] (Member having a recessed structure according to one embodiment of the present invention) Next, with reference to Figures 14 to 17, a member having a recessed structure according to one embodiment of the present invention will be described.

[0163] Figure 14 shows a perspective view of a member having a recessed structure according to one embodiment of the present invention (hereinafter referred to as "the first member 200"). Figure 15 shows a schematic cross-sectional view of the first member 200 shown in Figure 14 along line AA.

[0164] As shown in Figure 14, the first member 200 has a surface 202 and a back surface 204 that face each other. The first member 200 also has a recessed structure 250 on the side of the surface 202.

[0165] In the example shown in Figure 14, the front surface 202 and back surface 204 of the first member 200 are substantially rectangular in shape. However, the shape of the front surface 202 and back surface 204 is not particularly limited.

[0166] Furthermore, in the example shown in Figure 14, the recessed structure 250 has the shape of a bottomed groove extending in one direction, and three recessed structures 250 are arranged in parallel.

[0167] However, this is merely an example, and the shape and arrangement of the recessed structure 250 are not particularly limited. For example, the recessed structure 250 may be a bottomed structure or a through structure. The bottomed structure may be, for example, a bottomed hole and / or a bottomed groove. The through structure may be a through hole or a through groove. Similarly, the pattern of the recessed structure 250 may take any form.

[0168] As shown in Figure 15, the recessed structure 250 has an opening 252 on the surface 202. The recessed structure 250 also has a bottom surface 256 and side walls 257. In other words, the recessed structure 250 is partitioned by the opening 252, the bottom surface 256, and the side walls 257.

[0169] The first component 200 can be manufactured, for example, by the manufacturing method according to the present invention as described above.

[0170] Here, the first member 200 is characterized by having a streak pattern along the depth direction on its side wall 257.

[0171] This feature will be explained below with reference to Figure 16.

[0172] Figure 16 schematically shows the surface morphology of the side wall 257 of the recess structure 250. Figure 16 schematically shows a portion of the side wall 257 obtained when the recess structure 250 is cut through the extension axis in the direction along the surface 202 of the first member 200 and the extension axis in the depth direction.

[0173] As shown in Figure 16, in the first member 200, a continuous, uninterrupted line (hereinafter referred to as "continuous line") 280 is formed on the side wall 257 of the recess structure 250, extending from the first opening 252 to the bottom surface 256.

[0174] Note that in Figure 16, three continuous muscle 280s are shown. However, this is merely an example, and the number of continuous muscle 280s is not particularly limited.

[0175] Such continuous reinforcement patterns 280 are significant and not observed in conventionally etched components. In other words, the continuous reinforcement patterns 280 are a unique feature observed in the first component 200 manufactured by the manufacturing method according to the present invention as described above.

[0176] This pattern of 280 continuous fibers is thought to be formed for the following reasons.

[0177] As explained with reference to Figures 9 and 10 above, in the manufacturing method according to the present invention, the coated region 8a is selectively etched by the catalyst material 3 placed on the coated region 8a. Furthermore, as long as the relationship between the catalyst material 3 and the coated region 8a continues, the recessed structure 5 continues to advance in the depth direction.

[0178] In such an etching mechanism, the side walls 7 of the recessed structures 5 created by etching are affected by the state of the side surface of the catalyst material 3 that the side walls 7 are in contact with.

[0179] In other words, if the side surface of the catalyst material 3 has irregularities, the side wall 7 of the recessed structure 5 is thought to have a surface state with corresponding irregularities, reflecting the influence of such irregularities on the side surface of the catalyst material 3.

[0180] Furthermore, in the manufacturing method according to the present invention, the catalyst material 3 having such irregularities on its side surface progresses along the depth direction of the recessed structure 5 to the bottom surface 6 of the recessed structure 5. Therefore, it is considered that a pattern of continuous lines 280 corresponding to such irregularities is formed on the side wall 7 of the final recessed structure 5.

[0181] In addition to the features described above, or separately therefrom, the first member 200 may have the feature that the taper angle θ of the recessed structure 5 is in the range of 0° to 2°.

[0182] This feature will be explained below with reference to Figure 17.

[0183] Figure 17 schematically shows a cross-section of a recess along the extension axis L.

[0184] The recess 50 has an opening 52 on the surface of the member. The recess 50 also has a bottom surface 56 and side walls 57.

[0185] Although not clear from Figure 17, the recess 50 may be a round hole or a rectangular groove when viewed from above. Furthermore, the recess 50 may be a through structure. In that case, the recess 50 may have a second opening instead of a bottom surface 56.

[0186] For such a recess 50, the taper angle θ is determined as follows:

[0187]

number

[0188] The taper angle θ expressed by equation (1) serves as an indicator of the "perpendicularity" of the recess 50. That is, the smaller the taper angle θ, the more the inclination of the side wall 57 of the recess 50 with respect to the extension axis L is suppressed, and such a recess 50 can be said to be close to a "vertical recess structure". In particular, in the first member 200, if the taper angle θ of the recess structure 250 is in the range of 0° to 2°, the recess structure 250 can be said to have a vertical recess structure.

[0189] In the first member 200, the taper angle θ of the recessed structure 250 may be 1° or less.

[0190] Furthermore, in the first member 200, the depth of the recessed structure 250 may be 1 μm or more. In particular, in the first member 200, the depth of the recessed structure 250 is, for example, 2 μm or more, and preferably 3 μm or more.

[0191] (Other features of the first component 200) The first member 200 may be a single member or may be composed of multiple members.

[0192] When the first member 200 is composed of a single member, the first member 200 is composed of an element that, upon reaction with fluorine (F), forms a fluoride with a boiling point of 550°C or lower.

[0193] For example, the first member 200 may contain at least one element selected from the group consisting of B, C, Si, P, S, Ti, V, Cr, Ga, Ge, As, Se, Nb, Mo, Tc, Ru, Rh, Sn, Sb, Te, I, Ta, W, Re, Os, Ir, Pt, and Au. The material to be treated may further contain at least one element selected from the group consisting of H, N, Cl, Br, and O.

[0194] If the first member 200 is composed of a single member, the first member 200 may be, for example, a quartz glass substrate or a crystal substrate.

[0195] On the other hand, if the first member 200 is composed of multiple members, the first member 200 has an element on its surface 202 whose fluoride boiling point is 550°C or lower.

[0196] As mentioned above, such elements may be selected from the group consisting of, for example, B, C, Si, P, S, Ti, V, Cr, Ga, Ge, As, Se, Nb, Mo, Tc, Ru, Rh, Sn, Sb, Te, I, Ta, W, Re, Os, Ir, Pt, and Au. Furthermore, surface 202 may also contain at least one element selected from the group consisting of H, N, Cl, Br, and O.

[0197] For example, the first member 200 has one or more films disposed on a substrate material, and the outermost film may satisfy the aforementioned characteristics. Alternatively, the entire plurality of films may satisfy the aforementioned characteristics.

[0198] Such a film includes, for example, one or more selected from the group consisting of oxides, carbides, and nitrides of Si. Such a film may have, for example, at least one of SiO x , SiN y , SiCN, SiON, and SiC. Alternatively, together with the film, the substrate material may also have the aforementioned characteristics. Note that x of SiO x is a number satisfying 0 < x, and preferably 1.2 ≤ x ≤ 2. Also, y of SiN y is a number satisfying 0 < y, and preferably 0.8 ≤ y ≤ 4 / 3.

[0199] The first member 200 having such characteristics can be applied to various applications such as, for example, MEMS devices, microfluidic devices, semiconductor devices, optical devices, metasurface devices, molds for resin molding, window glass, and cover glass.

Examples

[0200] Hereinafter, examples of the present invention will be described.

[0201] In the following description, Examples 2 to 7 are examples, and Example 1 is a comparative example.

[0202] (Example 1) A concave structure was formed on one surface of the processing body by the following method.

[0203] First, a substrate made of quartz glass was prepared as the processing body. Also, a coating liquid containing a catalyst material was prepared. An i-line resist was used as the catalyst material, and this was mixed with a solvent (ethyl lactate, n-butyl acetate) to prepare the coating liquid.

[0204] The i-line resist used contains a novolac resin represented by the following chemical formula.

[0205] [ka] Therefore, the i-line resist has a hydroxyl group as a polar functional group.

[0206] Next, a coating solution was applied to the substrate surface by spin coating. Furthermore, a pattern of catalyst material was applied to the substrate surface by exposure and development. The pattern was a parallel line pattern with a width of approximately 3 μm and a pitch of approximately 3 μm.

[0207] Next, the substrate on which the catalyst material pattern was installed was cut to approximately 50 mm x 50 mm, and the cut sample was placed in the processing chamber. Gas etching was then performed on the sample in the processing chamber. A mixed gas of nitrogen gas and hydrogen fluoride gas (HF: 20 vol%, N2: 80 vol%) was used as the etching gas. The processing temperature was set to 250°C. The processing time was 10 minutes.

[0208] The processed material obtained after etching is referred to as "Sample 1".

[0209] (Examples 2-7) A recessed structure was formed on the substrate surface using the same method as in Example 1. However, in Examples 2 to 7, the composition of the etching gas was changed from that in Example 1 to form the recessed structure. Other processing conditions were the same as in Example 1.

[0210] Specifically, in Examples 2 to 7, a mixed gas of nitrogen gas, hydrogen fluoride gas, and hydrogen chloride gas was used as the etching gas. In Examples 2 to 7, the proportion of HF gas in the mixed gas was fixed at 20 vol%. The etching gas used in Example 2 consisted of 20 vol% HF gas, 1 vol% HCl gas, and 79 vol% N2 gas. In Example 2, the volume ratio of HCl gas to HF gas was set to 5 vol%.

[0211] The etching gas used in Example 3 consisted of 20 vol% HF gas, 5 vol% HCl gas, and 75 vol% N2 gas. In Example 3, the volume ratio of HCl gas to HF gas was set to 25 vol%.

[0212] The etching gas used in Example 4 consisted of 20 vol% HF gas, 10 vol% HCl gas, and 70 vol% N2 gas. In Example 4, the volume ratio of HCl gas to HF gas was set to 50 vol%.

[0213] The etching gas used in Example 5 consisted of 20 vol% HF gas, 20 vol% HCl gas, and 60 vol% N2 gas. In Example 5, the volume ratio of HCl gas to HF gas was set to 100 vol%.

[0214] The etching gas used in Example 6 consisted of 20 vol% HF gas, 50 vol% HCl gas, and 30 vol% N2 gas. In Example 4, the volume ratio of HCl gas to HF gas was 250 vol%.

[0215] The etching gas used in Example 7 consisted of 20 vol% HF gas, 80 vol% HCl gas, and 0 vol% N2 gas. In Example 7, the volume ratio of HCl gas to HF gas was set to 400 vol%.

[0216] The treated materials obtained after the etching process are referred to as "Sample 2" through "Sample 7," respectively.

[0217] (evaluation) In samples 1 to 7, the cross-sections of the recessed structures were observed using a scanning electron microscope (SEM), and various dimensions were measured. In samples 1 to 7, it was confirmed that multiple line-shaped grooves were formed on the surface as recessed structures.

[0218] Figures 18 and 19 show examples of cross-sections of the recessed structures obtained in Sample 1 and Sample 7, respectively.

[0219] These photographs reveal that in Sample 1 and Sample 7, a vertical recessed structure with a significantly suppressed taper angle is formed as a recessed structure. This morphology was similarly observed in Samples 2 through 6.

[0220] Etching depth, or etching amount, was measured during SEM observation. The etching rate, or etching amount per unit time, was calculated and summarized in Figure 20.

[0221] The graph confirmed that adding HCl gas to the etching gas increased the etching rate.

[0222] (One aspect of the present invention) The present invention may have the following embodiments.

[0223] (Aspect 1) A method for manufacturing a member having a recessed structure, The first step is to prepare a material to be treated that contains elements whose fluoride boiling point is 550°C or lower, A second step involves forming a catalyst material on a part of the surface of the object to be treated, The process includes a third step of exposing the workpiece to an etching gas in an environment of 80°C or higher to form a recessed structure in the portion of the workpiece where the catalyst material is formed, The etching gas includes a fluorine-containing gas and an acidic gas. The aforementioned acidic gas has a lower acid dissociation constant than hydrogen fluoride. Manufacturing method. (Aspect 2) The manufacturing method according to embodiment 1, wherein the ratio of the acidic gas to the fluorine-containing gas is 1 volume% or more. (Aspect 3) The manufacturing method according to embodiment 1 or 2, wherein the acidic gas is one or more selected from hydrogen chloride gas, hydrogen bromide gas, sulfur dioxide gas, sulfur trioxide gas, hydrogen iodide gas, and chlorine dioxide gas. (Aspect 4) The manufacturing method according to any one of embodiments 1 to 3, wherein the acidic gas is generated by water produced by the reaction of the object to be treated with the fluorine-containing gas. (Appendix 5) The manufacturing method according to embodiment 4, wherein the etching gas comprises one or more gases selected from silicon tetrachloride, titanium tetrachloride, tin tetrachloride, boron trifluoride, boron trichloride, boron tribromide, phosphorus trifluoride, phosphorus pentafluoride, antimony pentafluoride, iodine fluoride, titanium tetrachloride, titanium tetrafluoride, and aluminum trichloride. (Aspect 6) The manufacturing method according to any one of embodiments 1 to 5, wherein the etching gas further includes an inert gas as a diluent. (Aspect 7) The manufacturing method according to embodiment 6, wherein the ratio of the fluorine-containing gas and the acidic gas to the inert gas is 0.1% by volume or more and 100% by volume or less. (Pattern 8) The manufacturing method according to any one of embodiments 1 to 7, wherein the catalyst material promotes fluoride formation at the interface with the object to be treated. (Aspect 9) The method for producing the catalyst material according to any one of embodiments 1 to 8, wherein the catalyst material comprises an organic compound having a polar functional group. (Aspect 10) The catalyst material is an organic compound having one or more polar functional groups selected from hydroxyl groups, aldehyde groups, carboxyl groups, amino groups, sulfo groups, thiol groups, amide bonds, carbonyl groups, nitro groups, cyano groups, ether bonds, and ester bonds; and An organic compound having one or more structures selected from the group consisting of a phosphorus-containing structure and a ring structure containing at least one of nitrogen and oxygen; a method of production according to any one of embodiments 1 to 9, comprising one or more selected from the group. (Aspect 11) The manufacturing method according to embodiment 9, further comprising a fourth step between the second step and the third step of irradiating the catalyst material with irradiation light including deep ultraviolet light with a wavelength of 380 nm or less. (Aspect 12) The production method according to any one of Aspects 1 to 11, wherein the catalyst material is at least one selected from the group consisting of metal halides, transition metals, and transition metal oxides. (Aspect 13) The production method according to any one of Aspects 1 to 12, wherein the fluorine-containing gas is at least one selected from hydrogen fluoride gas and fluorine gas. (Aspect 14) The production method according to any one of Aspects 1 to 13, wherein the object to be treated contains at least one selected from the group consisting of B, C, Si, P, S, Ti, V, Cr, Ga, Ge, As, Se, Nb, Mo, Tc, Ru, Rh, Sn, Sb, Te, I, Ta, W, Re, Os, Ir, Pt, and Au. (Aspect 15) The production method according to Aspect 14, wherein the object to be treated further contains at least one selected from the group consisting of H, N, Cl, Br, and O. (Aspect 16) The object to be treated is SiO x , SiN y The production method according to Aspect 14, which is at least one selected from the group consisting of SiCN, SiON, and SiC. (Aspect 17) The production method according to any one of Aspects 1 to 16, wherein the object to be treated is composed of a single member. (Aspect 18) The production method according to Aspect 17, wherein the object to be treated is a quartz glass substrate, a boron-containing quartz glass substrate, a phosphorus-containing quartz glass substrate, a quartz crystal substrate, or a silicon substrate. (Aspect 19) The production method according to any one of Aspects 1 to 18, wherein the object to be treated has a substrate and a film formed on the substrate, and at least the film contains an element whose fluoride has a boiling point of 550°C or lower. (Aspect 20) The production method according to Aspect 19, wherein the film contains at least one selected from the group consisting of oxides, carbides, and nitrides of Si. [[ID=3{7]]

Description of Reference Numerals

[0224] 1 Object to be treated 3. Catalyst materials 5. Recessed structure 6. Base 7 side wall 7a First side wall portion 8a Covered area 8b Uncovered area 50 recesses 52 Aperture 56 Bottom 57 Side wall 100 components 110 Object to be processed 112 Surface 114 Back side 130 Catalyst materials 131 patterns 140a Covered area 140b Uncovered area 150 recessed structure 200 First component 202 Surface 204 Back side 250 recessed structure 252 Aperture 256 Bottom 257 Side wall 280 consecutive muscle (a) HF molecule (b) Si atom (c) OH group (d) Si-F bond (e) -δ part (f) +δ part (g) H2O molecule

Claims

1. A method for manufacturing a member having a recessed structure, The first step is to prepare a material to be treated that contains an element whose fluoride boiling point is 550°C or lower, A second step involves forming a catalyst material on a part of the surface of the object to be treated, The process includes a third step of exposing the workpiece to an etching gas in an environment of 80°C or higher to form a recessed structure in the portion of the workpiece where the catalyst material is formed, The etching gas includes a fluorine-containing gas and an acidic gas. The aforementioned acidic gas has a lower acid dissociation constant than hydrogen fluoride. Manufacturing method.

2. The manufacturing method according to claim 1, wherein the ratio of the acidic gas to the fluorine-containing gas is 1% by volume or more.

3. The manufacturing method according to claim 1 or 2, wherein the acidic gas is one or more selected from hydrogen chloride gas, hydrogen bromide gas, sulfur dioxide gas, sulfur trioxide gas, hydrogen iodide gas, and chlorine dioxide gas.

4. The manufacturing method according to claim 1 or 2, wherein the acidic gas is generated by the reaction between the object to be treated and the fluorine-containing gas.

5. The manufacturing method according to claim 4, wherein the etching gas comprises one or more gases selected from silicon tetrachloride, titanium tetrachloride, tin tetrachloride, boron trifluoride, boron trichloride, boron tribromide, phosphorus trifluoride, phosphorus pentafluoride, antimony pentafluoride, iodine fluoride, titanium tetrachloride, titanium tetrafluoride, and aluminum trichloride.

6. The manufacturing method according to claim 1 or 2, wherein the etching gas further includes an inert gas as a diluent.

7. The manufacturing method according to claim 6, wherein the ratio of the fluorine-containing gas and the acidic gas to the inert gas is 0.1% by volume or more and 100% by volume or less.

8. The manufacturing method according to claim 1 or 2, wherein the catalyst material promotes fluoride formation at the interface with the object to be treated.

9. The method for producing the catalyst according to claim 1 or 2, wherein the catalyst material comprises an organic compound having a polar functional group.

10. The catalyst material is an organic compound having one or more polar functional groups selected from hydroxyl groups, aldehyde groups, carboxyl groups, amino groups, sulfo groups, thiol groups, amide bonds, carbonyl groups, nitro groups, cyano groups, ether bonds, and ester bonds; and An organic compound having one or more structures selected from the group consisting of a phosphorus-containing structure and a ring structure containing at least one of nitrogen and oxygen; a method for producing the product according to claim 1 or 2, comprising one or more selected from the group.

11. The manufacturing method according to claim 9, further comprising a fourth step between the second and third steps of irradiating the catalyst material with irradiation light including deep ultraviolet light with a wavelength of 380 nm or less.

12. The manufacturing method according to claim 1 or 2, wherein the catalyst material is one or more selected from the group consisting of metal halides, transition metals, and oxides of transition metals.

13. The manufacturing method according to claim 1 or 2, wherein the fluorine-containing gas is one or more selected from hydrogen fluoride gas and fluorine gas.

14. The manufacturing method according to claim 1 or 2, wherein the material to be treated includes one or more selected from the group consisting of B, C, Si, P, S, Ti, V, Cr, Ga, Ge, As, Se, Nb, Mo, Tc, Ru, Rh, Sn, Sb, Te, I, Ta, W, Re, Os, Ir, Pt, and Au.

15. The manufacturing method according to claim 14, wherein the material to be treated further comprises one or more selected from the group consisting of H, N, Cl, Br, and O.

16. The treated object is SiO ｘ SiN ｙ The manufacturing method according to claim 14, wherein the material is one or more selected from the group consisting of SiCN, SiON, and SiC.

17. The manufacturing method according to claim 1 or 2, wherein the object to be processed is composed of a single component.

18. The manufacturing method according to claim 17, wherein the object to be treated is a quartz glass substrate, a boron-containing quartz glass substrate, a phosphorus-containing quartz glass substrate, a crystal substrate, or a silicon substrate.

19. The manufacturing method according to claim 1 or 2, wherein the object to be treated comprises a substrate and a film formed on the substrate, and at least the film contains an element whose fluoride boiling point is 550°C or lower.

20. The manufacturing method according to claim 19, wherein the film comprises one or more selected from the group consisting of oxides, carbides, and nitrides of Si.

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