Dry etching method

Abstract

To provide a method for etching precious metal films by a chemical etching process that does not require sputtering.SOLUTION: An etching method for dry etching a precious metal film formed on a substrate containing at least one precious metal element selected from the group consisting of gold and platinum group elements includes surface treatment of the precious metal film and removal of the surface treated areas.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a dry etching method, and more particularly to a dry etching method for removing a film containing a noble metal element such as platinum (Pt) or gold (Au) (noble metal film) by etching. [Background technology]

[0002] Precious metals such as platinum and gold are chemically stable, have low electrical resistance, and have high melting points, and therefore are attracting attention as electrode materials for semiconductor wafers, etc. Unnecessary parts of a precious metal film formed on a substrate are removed by etching to form a wiring pattern, but highly accurate microfabrication is essential to obtain the desired characteristics as an electrode, and etching technology plays an important role.

[0003] There are two types of etching techniques: wet etching and dry etching, which are used depending on the process. Wet etching keeps costs down and allows for mass production, but because precise processing is difficult, the proportion of dry etching has been increasing in recent years. In general dry etching, precious metal films are removed by sputtering, but due to their high chemical stability, it is very difficult to generate volatile compounds. Processing precious metal films by dry etching is considered difficult, but various dry etching methods are being considered.

[0004] For example, Patent Document 1 proposes a method for dry etching a platinum-containing metal film, which generates plasma of an etching gas made of a mixed gas containing hydrogen gas, carbon dioxide gas, methane gas, and a rare gas to dry etch the metal film. Patent Document 1 describes the use of argon gas as the rare gas.

[0005] On the other hand, Non-Patent Document 1 describes that when etching is performed by sputtering using argon gas, a substance with a low vapor pressure is generated as an etching reaction product, which re-adheres to the side of the photoresist pattern, which serves as the etching mask, and remains as a residue even during the removal process. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 5740281 [Non-patent literature]

[0007] [Non-Patent Document 1] Teruo Shibano, Kazuyasu Nishikawa, "Etching Technology of Platinum and High Dielectric Constant Materials for Capacitors", Applied Physics, The Japan Society of Applied Physics, 1994, Vol. 63, No. 11, pp. 1139-1142 Summary of the Invention [Problem to be solved by the invention]

[0008] In the case of typical dry etching of precious metal films, due to their high chemical stability, it is difficult to form volatile products, and etching has to rely on the sputtering phenomenon as described in Patent Document 1. However, as described in Non-Patent Document 1, etching by sputtering inevitably causes redeposition of reaction products onto the pattern sidewalls, making it difficult to control the pattern shape.

[0009] In view of the above circumstances, an object of the present invention is to provide a method for etching a noble metal film by a chemical etching process that does not require sputtering. [Means for solving the problem]

[0010] One aspect of the present invention relates to an etching method for dry etching a precious metal film formed on a substrate, the precious metal film containing at least one precious metal element selected from the group consisting of gold and platinum group elements, the dry etching method including surface-treating the precious metal film and removing the surface-treated portion.

[0011] Another aspect of the present invention relates to an etching method for dry etching a precious metal film formed on a substrate, the precious metal film containing at least one precious metal element selected from the group consisting of gold and platinum group elements, the dry etching method including surface-treating a predetermined portion of the precious metal film and removing the surface-treated portion to form an opening pattern. Effect of the Invention

[0012] According to the dry etching method of the present invention, the surface of the precious metal film is treated before the film is removed to activate the film so that the metal element on the activated metal film surface reacts with the etchant, and the surface-treated portion is removed. By repeating the surface treatment of the metal film and the removal of the surface-treated portion in the dry etching method of the present invention, the desired etching depth can be achieved. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The present invention will be described below, but the present invention is not limited to the examples in the following description.

[0014] (First embodiment) A dry etching method according to a first embodiment of the present invention is an etching method for dry etching a precious metal film formed on a substrate, the precious metal film containing at least one precious metal element selected from the group consisting of gold and platinum group elements, and includes surface-treating the precious metal film and removing the surface-treated portion.

[0015] The substrate on which the precious metal film is provided is not particularly limited, and examples thereof include semiconductor substrates, quartz glass substrates, resin substrates, non-alkali glass substrates, crystallized glass substrates on which β-quartz solid solution is precipitated, SiO2-TiO2-based glass substrates, multi-component glass ceramic substrates, silicon substrates, metal substrates, etc. Examples of semiconductor substrates include substrates made of single-element semiconductor materials such as silicon, germanium, and carbon, binary compound semiconductor materials such as gallium arsenide, indium phosphide, silicon carbide, aluminum nitride, aluminum oxide (sapphire), gallium nitride, and gallium oxide, and multi-component compound semiconductor materials made of compounds of multiple elements. Examples of resin substrates include substrates made of polyethylene terephthalate (PET), polycarbonate (PC), polystyrene (PS), polyimide, epoxy, low dielectric constant resins (parylene, fluoropolymer, cycloolefin), etc.

[0016] The precious metal film includes at least one precious metal element selected from the group consisting of gold and platinum group elements, which include platinum (Pt), iridium (Ir), palladium (Pd), ruthenium (Ru), rhodium (Rh), and osmium (Os). The precious metal film preferably contains at least one selected from the group consisting of gold, platinum, iridium and palladium, and more preferably contains at least one selected from the group consisting of gold, platinum and iridium. The precious metal film may be a single-layer film or a multi-layer film having two or more layers containing different precious metal elements.

[0017] The thickness of the precious metal film is not particularly limited, but from the viewpoint of the cycle treatment consisting of the formation and removal of the altered layer, the total thickness is preferably in the range of 0.1 nm to 1000 nm. The thickness of the film to be treated is preferably 0.1 nm or more, more preferably 0.5 nm or more, even more preferably 1 nm or more, and is preferably 1000 nm or less, more preferably 100 nm or less, and particularly preferably 50 nm or less.

[0018] The laminate having a precious metal film and a substrate may have a metal film other than the precious metal film between the precious metal film and the substrate, as long as the precious metal film is disposed as the outermost layer. Examples of the other metal film include metal films containing titanium (Ti), aluminum (Al), molybdenum (Mo), magnesium (Mg), chromium (Cr), tantalum (Ta), tungsten (W), niobium (Nb), tantalum (Ta), rhenium (Re), iron (Fe), silicon (Si), germanium (Ge), and tin (Sn). The other metal film may be a film consisting of one layer, or a multilayer film consisting of two or more layers.

[0019] <Surface treatment of metal film> In the dry etching method of the first embodiment, first, a surface treatment is performed on a precious metal film provided on a substrate (Step A). ​​In Step A, the surface treatment makes the precious metal in the precious metal film to be treated, which contains at least one precious metal element selected from the group consisting of gold and platinum group elements, chemically reactive.

[0020] Examples of the surface treatment method include oxidation treatment, nitriding treatment, oxynitriding treatment, sulfurization treatment, and oxysulfurization treatment.

[0021] The oxidation treatment includes a plasma treatment using a gas containing oxygen, in which an oxygen-containing plasma is supplied to the surface of the precious metal film and oxygen radicals in the oxygen-containing plasma are caused to act on the precious metal element in the precious metal film to activate it. For example, when the precious metal film is a platinum film containing platinum (Pt), platinum exists in a mixed oxidation state with oxidation numbers of 0, 2, and 4, with 0-valent platinum being the most chemically stable state with the highest concentration. By supplying oxygen-containing plasma to this state, the platinum on the surface of the precious metal film changes to an oxidation number of 2 and then to an oxidation number of 4. This forms a surface with a high concentration of highly reactive 4-valent platinum, which makes it easier to remove in the next process.

[0022] Examples of the gas containing oxygen for generating oxygen-containing plasma include oxygen gas (O2) and oxidizing gas. Examples of the oxidizing gas include oxygen sulfide (SO2), ozone gas (O3), carbon monoxide (CO), and nitrogen monoxide (NO). These may be used alone or in combination of two or more. When oxygen gas (O2) and an oxidizing gas are used in combination, the oxidation of the precious metal film is more likely to proceed. Also, a mixed gas of oxygen gas (O2) and at least one selected from the group consisting of hydrogen gas (H2), nitrogen gas (N2) and noble gases is preferably used. Examples of noble gases include argon (Ar) gas, helium (He) gas, neon (Ne) gas, krypton (Kr) gas, and xenon (Xe) gas. By mixing hydrogen gas (H2), the surface of the noble metal film can be easily activated, and by mixing a noble gas, the plasma can be stabilized. As the noble gas, argon (Ar) gas is preferred. Hydrogen gas (H2) is preferably mixed in the range of 0 to 10%, and the noble gas is preferably mixed in the range of 0% or more and less than 100%.

[0023] The plasma treatment is preferably carried out at a pressure in the range of 0.1 Pa to 1000 kPa. By carrying out the treatment at a pressure in this range, the surface of the precious metal film can be efficiently oxidized. The pressure during plasma treatment is preferably 0.1 Pa or more, more preferably 1 Pa or more, even more preferably 5 Pa or more, and particularly preferably 10 Pa or more, and is preferably 1000 kPa or less, more preferably 500 kPa or less, even more preferably 200 kPa or less, and particularly preferably 100 kPa or less.

[0024] The oxygen atom concentration in the plasma is 1×10 12 atoms / cm 3 It is preferable that the value is equal to or greater than 1×10 13 atoms / cm 3 More preferably, 1×10 14 atoms / cm 3 More than 1×10 is more preferable. 12 atoms / cm 3By supplying a plasma containing oxygen atoms of 1×10 or more, the precious metal film can be efficiently activated. For example, when the precious metal film is a platinum film containing platinum (Pt), tetravalent platinum can be efficiently generated. In addition, the upper limit of the oxygen atom concentration is determined by the gas pressure, so there is no particular upper limit to the oxygen atom concentration. 19 atoms / cm 3 Preferably, it is less than or equal to 1×10 18 atoms / cm 3 More preferably, the oxygen atom concentration in the plasma is 1×10 12 ~1×10 19 atoms / cm 3 The range is preferably:

[0025] In this embodiment, the plasma treatment is performed under a pressure of 10 Pa to 100 kPa, with oxygen atoms being introduced at 1×10 12 atoms / cm 3 It is preferable to use a plasma containing the above.

[0026] The plasma treatment is preferably carried out at a substrate temperature in the range of 15 to 200° C. If the treatment temperature is 15° C. or higher, the reaction proceeds efficiently, and if the substrate temperature is 200° C. or lower, an oxide layer can be formed on the surface of the precious metal film. The treatment temperature is more preferably 20° C. or higher, and even more preferably 25° C. or higher, and is more preferably 150° C. or lower, and even more preferably 100° C. or lower.

[0027] The plasma treatment time is preferably in the range of 0.1 to 100 minutes. If the treatment time is 0.1 minute or more, oxygen radicals react sufficiently with the precious metal element, and if it is 100 minutes or less, the treatment can be carried out efficiently, improving productivity. The treatment time is more preferably 0.5 minutes or more, even more preferably 1 minute or more, and particularly preferably 2 minutes or more. The treatment time is more preferably 20 minutes or less, even more preferably 10 minutes or less, and particularly preferably 3 minutes or less. If the treatment time is 3 minutes or less, an oxide layer can be formed in a thickness range of 0.3 to 5.0 nm on the surface of the precious metal film, and activation can be performed efficiently.

[0028] The plasma treatment can be carried out using a known device, and the flow rate at which the oxygen-containing plasma is supplied to the surface of the noble metal film may be set depending on the device.

[0029] The nitridation and oxynitridation treatments include plasma treatments using a gas containing nitrogen or a gas containing nitrogen and oxygen, in which a nitrogen-containing plasma or a hydrogen-containing plasma is supplied to the surface of the precious metal film, and nitrogen radicals in the nitrogen-containing plasma or nitrogen radicals in the hydrogen-containing plasma are caused to act on the precious metal element in the precious metal film to activate it. For example, when the precious metal film is a platinum film containing platinum (Pt), reactive groups containing nitrogen (N), such as nitro groups or amino groups, are formed on the surface of the platinum film, which forms a highly reactive nitride layer on the surface, making it easier to remove in the next process.

[0030] The nitrogen-containing gas for generating the nitrogen-containing plasma may be nitrogen gas (N2) alone or a mixed gas of nitrogen gas and at least one gas selected from the group consisting of oxygen gas and hydrogen gas. By mixing oxygen gas, nitro (NO2) groups can be formed on the surface of the precious metal film, and by mixing hydrogen gas, amino (NH2) groups can be formed on the surface of the precious metal film. Oxygen gas is preferably mixed in the range of 0 to 30%, and hydrogen gas is preferably mixed in the range of 0 to 30%.

[0031] The gas containing nitrogen and hydrogen for generating the hydrogen-containing plasma is a mixed gas containing nitrogen (N2) gas and hydrogen (H2) gas. In the mixed gas, nitrogen (N2) gas is preferably mixed in the range of 20 to 80%.

[0032] The plasma treatment is carried out by injecting nitrogen atoms at a rate of 1×10 12 atoms / cm 3 It is preferable to use plasma containing 1×10 or more. 12 atoms / cm 3 By supplying the above-mentioned plasma containing nitrogen atoms, a reaction layer containing nitrogen can be formed on the surface of the noble metal film. The nitrogen atom concentration in the plasma is 1×1013 atoms / cm 3 More preferably, the surface treatment efficiency is 1×10 19 atoms / cm 3 Preferably, it is less than or equal to 1×10 14 atoms / cm 3 The following is more preferred:

[0033] The pressure, temperature and time during the plasma treatment are the same as those in the above-mentioned oxidation treatment.

[0034] The sulfurization treatment and oxysulfurization treatment include plasma treatment using a gas containing sulfur or a gas containing sulfur and oxygen, in which a sulfur-containing plasma or an oxygen disulfide (SO2)-containing plasma is supplied to the surface of the precious metal film, and sulfur radicals in the sulfur-containing plasma or sulfur radicals and sulfur monoxide (SO) radicals in the oxygen disulfide (SO2)-containing plasma act on the precious metal elements in the precious metal film to activate them. For example, if the precious metal film is a platinum film containing platinum (Pt), the surface of the platinum film is sulfitized (adding SO2) and sulfated (adding SO3), which forms a highly reactive nitride layer on the surface, making it easier to remove in the next process.

[0035] Examples of sulfur-containing gases for generating sulfur-containing plasma include sulfur dioxide (SO2) and hydrogen sulfide (H2S).

[0036] Plasma treatment uses sulfur monoxide (SO) radicals at 1×10 12 atoms / cm 3 It is preferable to use plasma containing 1×10 or more. 12 atoms / cm 3 By supplying the plasma containing the above sulfur atoms, a reactive layer having a high oxidation number can be formed on the surface of the precious metal film. The sulfur monoxide (SO) radical concentration in the plasma is 1×10 13 atoms / cm 3 More preferably, the reaction time is 1×10 or more. 19 atoms / cm 3Preferably, it is less than or equal to 1×10 14 atoms / cm 3 The following is more preferred:

[0037] The pressure, temperature and time during the plasma treatment are the same as those in the above-mentioned oxidation treatment.

[0038] The surface treatment of the precious metal film is preferably carried out by including at least one treatment selected from the group consisting of oxidation, nitridation, oxynitridation, sulfidation, sulfation, and sulfitation, and from the viewpoint of the treatment for forming volatiles, it is more preferable to carry out oxidation treatment, oxynitridation, or sulfation, with oxidation treatment being even more preferable.

[0039] In the case where the precious metal film is a platinum film containing platinum (Pt), in the step A, when the precious metal film after the surface treatment is analyzed by X-ray photoelectron spectroscopy (XPS), it is preferable that the film has a peak at a high energy position E2 that is 3 eV or more higher than the binding energy position E1 of the metal 0 valence, and the area of ​​the peak observed at the high energy position E2 is 10% or more of the area of ​​the peak observed at the binding energy position E1 of the metal 0 valence. That is, it is preferable that the film has a peak at a high energy position E2 of 74 eV that is 3 eV or more higher than the binding energy position E1 of the metal 0 valence of 71 eV (electron volt) from the spin 7 / 2 of the Pt4f region, and even when the photoelectron escape angle is measured in the range of 30 degrees to 90 degrees, the area of ​​the peak observed at the high energy position E2 is 10% or more of the area of ​​the peak observed at the binding energy position E1 of the metal 0 valence. This result shows that Pt with an oxidation number of 4 is formed on the surface of the precious metal film in a thickness range of 0.3 to 10 nm. When the area of ​​the peak observed at the high energy position E2 is 10% or more of the area of ​​the peak observed at the binding energy position E1 of the zero-valent metal, activation of the noble metal film proceeds and the film becomes easier to remove in the subsequent step B. The area of ​​the peak observed at the high energy position E2 is preferably 10% or more, more preferably 20% or more, relative to the area of ​​the peak observed at the bond energy position E1 of the zero-valent metal, and the upper limit is preferably 50% or less, more preferably 40% or less, and even more preferably 30% or less, in order to ensure removal in the subsequent step B. That is, such a value is preferably in the range of 10 to 50%.

[0040] <Removal of surface treated parts> After the surface treatment of the precious metal film in step A, the surface-treated portion is removed. The precious metal film is removed by applying an etchant to the surface-treated portion. Since the surface of the precious metal film is in an activated state that is easily reactive due to step A, when the etchant is applied to the surface-treated portion, the activated precious metal reacts with the etchant to form a volatile compound (e.g., an organic complex).

[0041] The etchant may be an organic substance containing either a carboxyl group (-COOH) or a carbonyl group (-C(=O)-). Examples of organic substances containing either a carboxyl group or a carbonyl group include organic acids (monocarboxylic acids, dicarboxylic acids) such as formic acid (HCOOH), acetic acid (CH3COOH), propionic acid (C2H5COOH), butyric acid, valeric acid, and oxalic acid, carbon monoxide (CO), alcohols, and diketones such as acetylacetone (C5H8O2), amines, and diamines. Among these, from the viewpoint of forming a highly reactive and highly volatile complex, formic acid, acetic acid, propionic acid, butyric acid, and acetylacetone are preferred, and formic acid is more preferred.

[0042] The organic substance is preferably applied to the surface-treated portion in the form of vapor, and the organic complex formed by the application of the organic vapor can be efficiently volatilized.

[0043] When the organic vapor is applied, a vaporized (gasified) organic matter may be supplied to the surface-treated portion of the precious metal film, or a plasma formed by the organic vapor (organic plasma) may be supplied to the surface-treated portion of the precious metal film, and the organic matter in the organic plasma may be allowed to act on the activated precious metal, thereby generating a volatile compound on the surface of the precious metal film. For example, when the precious metal film is a platinum film containing platinum (Pt) and a removal treatment is performed using formic acid, a platinum-formic acid complex is formed by tetravalent platinum and formic acid.

[0044] The removal plasma treatment is preferably carried out under a pressure of 10 Pa to 10,000 kPa. When the removal pressure is 10 Pa or more, organic vapor is sufficiently supplied to the surface to facilitate reaction, while when the removal pressure is 10,000 kPa or less, the organic complex can be desorbed into the gas phase. The removal pressure is more preferably 50 Pa or more, even more preferably 100 Pa or more, and more preferably 1000 kPa or less, even more preferably 100 kPa or less, particularly preferably 10 kPa or less, and most preferably 1 kPa or less.

[0045] The organic matter concentration in the organic plasma is 1×10 12 molecules / cm 3 More preferably, it is 1×10 15 molecules / cm 3 More preferably, the organic matter concentration is 1×10 or less to prevent the organic matter from coagulating and stopping the reaction. 19 molecules / cm 3 Preferably, it is less than or equal to 1×10 17 molecules / cm 3 The following is more preferred:

[0046] The treatment temperature is preferably 120° C. or less for the substrate, since the organic complex formed can be efficiently volatilized by treating the substrate at a temperature of 120° C. or less. The treatment temperature is preferably 100° C. or less, and more preferably 80° C. or less, and from the viewpoint of stably reacting the surface of the precious metal film, the treatment temperature is preferably 20° C. or more, more preferably 25° C. or more, even more preferably 40° C. or more, and particularly preferably 60° C. or more. Therefore, the treatment temperature is preferably in the range of 20 to 120° C.

[0047] The removal treatment time is preferably in the range of 0.1 to 10 minutes. If the treatment time is 0.1 minute or more, the etchant sufficiently reacts with the surface of the activated precious metal film, and if it is 10 minutes or less, the treatment can be carried out efficiently, improving productivity. The treatment time is more preferably 0.5 minutes or more, even more preferably 2 minutes or more, and is more preferably 8 minutes or less, even more preferably 5 minutes or less.

[0048] As described above, the precious metal film containing the precious metal element can be removed, and a desired thickness can be removed by repeating steps A and B. It is preferable to repeat steps A and B one or more times, and there is no particular upper limit since it is sufficient to remove the desired thickness.

[0049] Second embodiment A dry etching method according to a second embodiment of the present invention is an etching method for dry etching a precious metal film formed on a substrate, the precious metal film containing at least one precious metal element selected from the group consisting of gold and platinum group elements, and includes surface-treating a predetermined portion of the precious metal film and removing the surface-treated portion to form an opening pattern. The second embodiment can be performed in the same manner as the first embodiment, except that the opening pattern is formed by etching the precious metal film.

[0050] The opening pattern is an opening formed by combining a desired shape and / or lines of a specified width, and can be formed by performing the above steps A and B while a protective sheet having the desired opening pattern is superimposed on the surface of the precious metal film. By repeating steps A and B, an opening pattern of a desired thickness can be formed, and it is preferable to repeat steps A and B one or more times.

[0051] The dry etching method of the present invention makes it possible to etch a precious metal film containing a chemically stable precious metal without the need for sputtering, and therefore makes it easy to control the shape of an opening pattern formed by etching. Therefore, the dry etching method of the present invention is useful for manufacturing semiconductor substrates, and can be used for semiconductor memories such as nanosheet logic MOSFET transistors and dynamic random access memories (DRAMs), micro electro mechanical systems (MEMS) devices, processing (mask production) of EUV (extreme ultraviolet) blanks, spintronics, magnetic memories, etc. EXAMPLES

[0052] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these. Examples 1 to 3 are examples, and Examples 4 and 5 are comparative examples.

[0053] (Example 1) In Example 1, the platinum thin film was etched by surface treatment with oxygen plasma and removal of the surface layer with formic acid vapor. First, a silicon wafer was coated with a SiO2 film by DC magnetron sputtering (Ar gas, gas pressure 4.0×10 -1 Pa, Pt target, input power density per target area 5.0 W / cm 2 A platinum thin film was formed to obtain a laminate under the following conditions: target-substrate distance: 45 mm, deposition rate: 12 nm / min. The thickness of the platinum thin film was 20 nm. The same results were obtained by introducing an adhesive layer between the silicon wafer and the platinum thin film.

[0054] Next, the surface of the platinum thin film was subjected to plasma treatment under the following conditions. <Surface treatment conditions> Surface treatment method: Plasma Processing gas: Ar and O2 mixed gas (O2 concentration 3%) Processing pressure: 96Pa Substrate temperature: 20℃ Processing time: 2 minutes

[0055] Next, without exposing the laminate to the atmosphere, the surface treatment layer of the platinum thin film was removed under the following conditions: A platinum-formic acid complex was formed by supplying formic acid vapor to the surface-treated platinum thin film while heating the substrate. <Conditions for removing surface treatment layer> Surface treatment method: Heating Process gas: Formic acid Processing pressure: 1kPa Substrate temperature: 80℃ Processing time: 5 minutes

[0056] The platinum thin film was etched by repeating the above surface treatment and removal of the surface treatment layer. The thickness of the thin film after etching was calculated by ellipsometry, and the etching rate per cycle was found to be 0.34 nm / cycle.

[0057] In addition, when the platinum thin film was analyzed by X-ray photoelectron spectroscopy (XPS) after surface treatment, it had a peak at a high energy position of 74 eV, which is more than 3 eV higher than the binding energy position of 71 eV for platinum valence 0, and the area of ​​the high energy position 4 valence peak was 20% larger than the area of ​​the peak at the binding energy position of 71 eV for platinum valence 0. Due to the spin multiplicity, the peaks due to 7 / 2 and 5 / 2 spins were observed to be split by about 3.3 eV in a ratio of 4:3.

[0058] (Example 2) The same procedure as in Example 1 was repeated except that the surface treatment time was 5 minutes and the surface treatment layer removal temperature was 20°C.

[0059] (Example 3) The same procedure as in Example 1 was repeated, except that the surface treatment time was changed to 5 minutes.

[0060] (Example 4) The same procedure as in Example 1 was carried out except that no surface treatment was carried out and only the surface treatment layer was removed.

[0061] (Example 5) The same procedure as in Example 1 was carried out, except that only the surface treatment was carried out and the surface treatment layer was not removed.

[0062] The results are shown in Table 1.

[0063] [Table 1]

[0064] As can be seen from Table 1, in Examples 4 and 5, the platinum thin film could not be etched, whereas in Examples 1 to 3, the platinum film surface was treated and the surface-treated portion was removed, allowing stable etching.

[0065] As described above, the present specification discloses the following: <1> 1. An etching method for dry etching a precious metal film formed on a substrate, the precious metal film containing at least one precious metal element selected from the group consisting of gold and platinum group elements, the dry etching method comprising: surface-treating the precious metal film; and removing the surface-treated portion. <2> An etching method for dry etching a precious metal film formed on a substrate, the precious metal film containing at least one precious metal element selected from the group consisting of gold and platinum group elements, the dry etching method including surface-treating a predetermined portion of the precious metal film and removing the surface-treated portion to form an opening pattern. <3> The precious metal element is at least one selected from the group consisting of gold, platinum, iridium, and palladium. <1> or <2> The dry etching method according to claim 1 . <4> The surface treatment includes at least one treatment selected from the group consisting of oxidation, nitridation, oxynitridation, sulfurization, and oxysulfurization. <1> ~ <3> 13. The dry etching method according to claim 12, <5> The surface treatment includes an oxidation treatment, and the oxidation treatment is a plasma treatment using a gas containing oxygen. <4> The dry etching method according to claim 1 . <6> The plasma treatment is carried out under a pressure of 10 Pa to 100 kPa, and oxygen atoms are introduced into the plasma at a rate of 1×10 12 atoms / cm 3 The method is carried out using plasma containing the above. <5> The dry etching method according to claim 1 . <7> the precious metal element is platinum, and when the precious metal film after the surface treatment is analyzed by X-ray photoelectron spectroscopy, it has a peak at a high energy position E2 that is 3 eV or more higher than the binding energy position E1 of the metal with a valence of zero, and the area of ​​the peak observed at the high energy position E2 is 10% or more of the area of ​​the peak observed at the binding energy position E1 of the metal with a valence of zero; <1> ~ <6> 13. The dry etching method according to claim 12, <8> The removal of the surface-treated portion includes applying an organic vapor containing an organic substance having any one of a carboxyl group and a carbonyl group to the surface-treated portion. <1> ~ <7> 13. The dry etching method according to claim 12, <9> The organic vapor is allowed to act on the surface-treated portion and treated at a substrate temperature of 120° C. or less. <8> The dry etching method according to claim 1 . <10> treating the surface-treated portion with a plasma formed by the organic vapor; <8> or <9> The dry etching method according to claim 1 . <11> The surface treatment of the noble metal film and the removal of the surface-treated portion are repeated one or more times. <1> ~ <10> 13. The dry etching method according to claim 12,

Claims

1. 1. An etching method for dry etching a precious metal film formed on a substrate, the precious metal film including at least one precious metal element selected from the group consisting of gold and platinum group elements, comprising: A dry etching method comprising the steps of: surface-treating the noble metal film; and removing the surface-treated portion.

2. 1. An etching method for dry etching a precious metal film formed on a substrate, the precious metal film including at least one precious metal element selected from the group consisting of gold and platinum group elements, comprising: a dry etching method including surface-treating a predetermined portion of the noble metal film and removing the surface-treated portion to form an opening pattern.

3. 3. The dry etching method according to claim 1, wherein the noble metal element is at least one selected from the group consisting of gold, platinum, iridium, and palladium.

4. 3. The dry etching method according to claim 1, wherein the surface treatment includes at least one treatment selected from the group consisting of oxidation, nitridation, oxynitridation, sulfurization, and oxysulfurization.

5. 5. The dry etching method according to claim 4, wherein the surface treatment includes an oxidation treatment, the oxidation treatment being a plasma treatment using a gas containing oxygen.

6. The plasma treatment is carried out under a pressure of 10 Pa to 100 kPa, and oxygen atoms are introduced at a rate of 1×10 １２ atoms / cm ３ The dry etching method according to claim 5 , wherein the dry etching method is carried out using a plasma containing the above.

7. the noble metal element is platinum, 3. The dry etching method according to claim 1, wherein when the precious metal film after the surface treatment is analyzed by X-ray photoelectron spectroscopy, the precious metal film has a peak at a high energy position E2 that is 3 eV or more higher than a binding energy position E1 of a metal with a valence of zero, and the area of ​​the peak observed at the high energy position E2 is 10% or more of the area of ​​the peak observed at the binding energy position E1 of a metal with a valence of zero.

8. 3. The dry etching method according to claim 1, wherein removing the surface-treated portion comprises reacting an organic vapor containing an organic substance having either a carboxyl group or a carbonyl group with the surface-treated portion.

9. 9. The dry etching method according to claim 8, wherein the organic vapor is allowed to act on the surface-treated portion and the treatment is performed at a substrate temperature of 120[deg.] C. or less.

10. 9. The dry etching method according to claim 8, wherein the surface-treated portion is treated with plasma formed by the organic vapor.

11. 3. The dry etching method according to claim 1, wherein the surface treatment of the noble metal film and the removal of the surface-treated portion are repeated one or more times.

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