JP2006076851A - Diamond film, its producing method, electrochemical element, and its producing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a diamond film having high surface smoothness and electrical conductivity; and a method for producing the same. <P>SOLUTION: The diamond film is synthesized on a base body and contains nitrogen in an amount of ≥3×10<SP>18</SP>cm<SP>-3</SP>. The diamond film can be produced on a substrate by a CVD method using a raw material gas containing a hydrocarbon, hydrogen and ≥0.5% nitrogen source gas. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a diamond film having good flatness and conductivity and a method for producing the same. The present invention also relates to an electrochemical element that uses a diamond film as an electrode and utilizes an oxidation-reduction reaction on the electrode surface to identify a substance to be measured and / or detect its concentration, and a method for manufacturing the same.

It is widely known that diamonds bonded by covalent bonds due to sp ³ hybrid orbitals of carbon atoms have unique physical properties that cannot be obtained by other materials due to their high binding energy. In recent years, it has become possible to synthesize and form high-quality diamond films (diamond films) at low pressure using chemical vapor deposition (CVD). As a film forming method, hot filament CVD or microwave CVD is generally used.

  According to such a diamond film formation method, a single crystal diamond film can be formed as a homoepitaxial film on a diamond substrate (natural or high-pressure synthetic diamond). A polycrystalline diamond film is formed as a heteroepitaxial film on a silicon, metal or quartz substrate.

  Thus, it is possible to synthesize high-quality single crystal diamond on a diamond substrate. However, in this case, it is necessary to use natural stone or high-temperature high-pressure synthetic diamond as a substrate, and the size of such a substrate is as follows. Currently, the maximum is about 10 mm square.

  On the other hand, in order to form a polycrystalline diamond film, a substrate having a relatively large area such as silicon can be used. However, since the polycrystalline diamond film is polycrystalline, the surface unevenness is extremely large. As described above, in a polycrystalline diamond film having a large surface irregularity, various problems occur in structure or process in a practical form when applied to coating materials, electrodes, various devices, and the like. For example, when a device or the like is manufactured using a polycrystalline diamond film, since the surface is not flat, the accuracy of the resist pattern is lowered, and it is difficult to form a fine pattern by lithography.

  In order to evaluate the practicality of the polycrystalline diamond film, at the trial production level, it has often been attempted to polish the surface after the film formation. However, since diamond is the hardest material, surface polishing is difficult, and further, a polishing step is indispensable, and thus there is a problem that the cost is increased significantly in practical use.

  As described above, although the conventional diamond film has extremely excellent material properties, there are problems in the cost, size, and surface smoothness of the substrate material and the like, and it has been difficult to put into practical use.

  On the other hand, using an electrode as a detection element, the current or potential change based on the reaction that occurs at the electrode interface is detected, and the concentration of various substances such as ions, inorganic compounds, organic compounds, polymer compounds, biological substances, etc. is electrochemically determined. There are known electrochemical devices for measurement. Carbon electrodes, metal oxides, metals, semiconductors, and the like are used for the electrodes of such electrochemical elements, and the element performance largely depends on the characteristics of the electrode materials.

Diamond is attracting attention as an electrode material for such electrochemical elements. As described above, diamond has extremely excellent physical and chemical stability because the crystal is composed of covalent bonds due to strong four-coordinate sp ³ hybrid orbitals between carbon atoms. In particular, chemical resistance and corrosion resistance are indispensable characteristics as a high-performance and highly reliable electrode material.

  In order to use diamond as such an electrode material, higher conductivity is required. Diamond is a good insulator with a band gap of 5.5 eV. However, as with silicon, conductivity by impurity conduction can be imparted by doping impurities. Today, the most commonly known boron-doped diamond can be produced with a specific resistance of several Ωcm or less.

  Single crystal diamond synthesized at high temperature and high pressure is usually 5 mm square or less, and it is difficult to synthesize a single crystal larger than that, and it is very expensive. In an electrochemical element, the higher the surface area of the electrode, the higher the sensitivity, so that a diamond film formed on a substrate such as single crystal silicon is usually used.

  As a method for synthesizing a diamond film, a microwave plasma chemical vapor deposition (MPCVD) method using a discharge by microwave is generally used. In the MPCVD method, hydrogen gas containing about several percent of methane gas is introduced into a vacuum chamber, and microwave plasma is generated in a relatively high pressure atmosphere of about several tens of Torr. A substrate is placed in the plasma, and a diamond film is formed on the substrate. At this time, the plasma has a high density and is at a high temperature of 800 ° C. or higher. Therefore, the substrate is limited to those having heat resistance that can be placed in such high-temperature plasma, and silicon, metal, ceramics, or the like is used.

  In such a conventional MPCVD method, when the substrate is made of a material different from diamond such as silicon, the diamond generated on the substrate becomes polycrystalline. In particular, it is necessary to use high-quality diamond in order to make diamond with high chemical resistance, but when crystallinity is improved with polycrystal, crystals in each plane orientation grow competitively. Therefore, the unevenness of the surface becomes large.

  Regarding the basic electrochemical characteristics using diamond as an electrode, the diamond electrode is an aqueous solution in which both oxygen generation and hydrogen generation by electrolysis of water occur only under a large overvoltage. It is known to show a large potential window (see, for example, Non-Patent Document 1). In this document, for example, glassy carbon, which is an allotrope, is 2.8 V, and highly oriented graphite is 2.2 V, while diamond is 3.5 V. It has also been reported that the diamond electrode has a very small background current value, which is about two orders of magnitude smaller than the glassy carbon. This suggests that the S / N ratio of the electrochemical device can be dramatically improved.

  In addition, as an example of an electrochemical element, for example, an electrode for electrochemical test / analysis made of diamond to which conductivity is added by an ion implantation method is shown (for example, see Patent Document 1). The advantages of the analysis are that there is a wide potential region (potential window) where hydrogen generation and oxygen generation (or metal elution) do not occur by electrolysis, and the residual current (base current considered as noise) in the potential window is low. It is shown to be excellent as an indicator electrode for chemical testing and analysis.

  In addition, using a diamond electrode, Fe (CN) 63- / 4-, Ru (NH3) 63 + / 2 +, IrCl62- / 3-, 4-methylcatechol, dopamine, methylviologen, ferrocene, hydroquinone, ascorbic acid There are also literatures that describe redox characteristics such as diamond electrodes and that diamond electrodes are promising as electrochemical devices (see, for example, Non-Patent Documents 2 and 3).

  Thus, since diamond has a wide potential window, when applied to an electrode of an electrochemical device, more reactive species can be detected and the background current is small compared to other electrode materials. Since the S / N ratio can be dramatically improved, high sensitivity detection is possible.

  It is known that diamond having such a wide potential window can be applied to a detection electrode of an electrochemical element to simultaneously measure a multi-component system (for example, see Patent Document 2). Here, diamond is produced by the general MPCVD method described above, and conductivity is obtained by doping with boron. As the substrate, in addition to silicon, metals and compounds thereof can be used. In addition to boron, nitrogen, phosphorus and the like are cited as dopants.

  Further, Patent Document 2 describes that a detection electrode made of diamond is a microelectrode, and detection sensitivity can be increased by increasing the surface area of the detection unit. However, there is no description about the structure and dimensions of the microelectrode and the manufacturing method thereof.

  As described above, the electrochemical device using diamond as an electrode has an advantage due to the material property of being physically or chemically stable, a wide potential window and a low back compared to the conventional electrochemical device. It can be said that it is excellent in terms of both electrochemical practical characteristics such as ground current. However, further high sensitivity and cost reduction are indispensable for practical use.

  As shown in Patent Document 2, high sensitivity can be expected by using a detection portion as a microelectrode, but its structure and manufacturing method have not been clarified.

  On the other hand, since the conventional diamond synthesis method requires a high temperature of 800 ° C. or higher, the substrate is limited to a heat-resistant substrate such as silicon. In addition, as the substrate, single crystal silicon is used because it is relatively easy to grow and is easy to obtain because it is a mass-produced product, but the cost is lower than that of glass or polymer substrate. Even when the above-described microelectrode formation is taken into account, the substrate is electrically conductive, so that element isolation is impossible.

Furthermore, since the conventional synthesis method uses a polycrystalline diamond film, the surface unevenness is large, and for example, even when processing into a microelectrode, it is not easy to apply a high-precision lithography technique.
Japanese Patent Publication No. 22-22900 Japanese Patent Laid-Open No. 11-83799 Catalyst 1999 April p262-p269 GM Swain et al., Anal. Chem., 67, (1995), 2812-2821 GM Swain et al. Electrochem. Soc. Proceedings, 96-9, (1996), 138-148

  The present invention has been made in consideration of the above problems, and an object thereof is to provide a diamond film having high surface smoothness and conductivity and a method for producing the same.

  Another object of the present invention is to provide a highly sensitive and low cost electrochemical device using a diamond film as an electrode material and a method for producing the same.

In order to solve the above problems, one embodiment of the present invention provides a diamond film synthesized over a substrate, the diamond film including nitrogen of 3 × 10 ¹⁸ cm ⁻³ or more.

  In such a diamond film, the crystal grain size is reduced by containing a predetermined amount of nitrogen. As a result, the smoothness of the surface is improved, and the flatness is very good with a root mean square surface roughness of less than 50 nm. This diamond film also has the characteristics that the resistivity is low and the conductivity is excellent.

  Such a diamond film having good flatness and conductivity can be suitably used for coating materials, electrodes, various electronic devices, and the like.

  As the base on which the diamond film is formed, one selected from the group consisting of a silicon substrate, a quartz substrate, a ceramic substrate, and a metal substrate can be used.

The diamond film can be formed on the substrate by a CVD method using a source gas containing hydrocarbon, hydrogen, and a nitrogen source gas of 0.5% or more. As described above, a diamond film containing nitrogen of 3 × 10 ¹⁸ cm ⁻³ or more can be easily obtained by a CVD method using a source gas containing a predetermined amount of nitrogen source gas.

  Thus, by adding a predetermined amount of nitrogen source gas to the raw material gas in the CVD method, CN and C2 (dimer) in the reaction system increase, and their generation density increases, resulting in a crystal. A diamond film having a small particle size and high surface smoothness can be obtained.

  In this case, the CVD method is preferably a plasma CVD method using microwave plasma of 1 kW or more.

The present invention is also an electrochemical device comprising a pair of electrodes and detecting and measuring the type and / or concentration of the substance to be measured using an oxidation-reduction reaction on the electrode surface, Provided is an electrochemical device characterized in that one surface is made of a diamond film containing nitrogen of 3 × 10 ¹⁸ cm ⁻³ or more.

  Thus, by using a diamond film on the electrode surface, it has very good chemical and physical stability due to strong diamond bonding, and very high reliability compared to other electrode materials The electrochemical element which shows is obtained. In such an electrochemical device, since the electrode has a wide potential window and a small background current, which are electrochemical characteristics peculiar to diamond, it is possible to measure a wider range of substances to be measured and a high S / N ratio is shown, and high sensitivity can be achieved.

  In the electrochemical device of the present invention, the diamond film can be formed in an arbitrary pattern on the same substrate to constitute a plurality of micro or nanoscale microelectrodes.

  Furthermore, in the electrochemical device of the present invention, the diamond film contains a predetermined amount of nitrogen, thereby reducing the crystal grain size. As a result, the surface smoothness is improved, and the flatness is the root mean square surface roughness. Improvement to less than 50 nm. Thereby, the following advantages are obtained as an electrochemical element.

  1. The diamond film can be finely processed by photolithography or electron beam lithography. Thus, by forming a fine pattern on the diamond film, the sensitivity of the element can be improved.

  2. Since conductivity can be imparted to diamond, it can function as an electrode of an electrochemical element.

  Furthermore, the present invention is a method for producing an electrochemical device comprising a pair of or more electrodes and detecting and measuring the type and / or concentration of the substance to be measured using an oxidation-reduction reaction on the electrode surface, The method includes a step of forming a diamond film on at least one surface of the electrode by a plasma CVD method using a source gas containing hydrocarbon, hydrogen, and nitrogen source gas of 0.5% or more. A method for manufacturing an electrochemical device is provided.

  Thus, by adding a predetermined amount of nitrogen source gas to the raw material gas in the CVD method, CN and C2 (dimer) in the reaction system increase, and their generation density increases, resulting in a crystal. A diamond film having a small particle size and high surface smoothness can be obtained. Thereby, the following advantages are obtained as an electrochemical element.

  Since each generation density of CN and C2 (dimer) increases, it can be formed on a silicon oxide film (thermal oxide film). As a result, a diamond film can be formed after a thermal oxide film is formed on a conductive silicon substrate. In this way, element isolation is facilitated by forming a diamond film on a silicon oxide film.

  Such a method for producing an electrochemical element further comprises a step of patterning the diamond film into an arbitrary shape by a lithography method or an electron beam lithography method following the step of forming a diamond film on a substrate. I can do it.

  According to the present invention, a diamond film having excellent surface flatness and good conductivity can be easily obtained by containing a predetermined amount of nitrogen. This diamond film has high hardness, high Young's modulus, high chemical resistance, high heat resistance, high thermal conductivity, wide band gap, high resistivity, semiconductor characteristics can be obtained through impurity control, and high electron transfer And excellent characteristics of having a high hole mobility.

  In addition, by using such a diamond film as an electrode, an electrochemical element having very excellent chemical and physical stability and extremely high reliability compared to other electrode materials can be manufactured at low cost. It is obtained by. This electrochemical element can measure a wide range of substances to be measured, exhibits a high S / N ratio, and can achieve high sensitivity.

  The best mode for carrying out the invention will be described below.

  FIG. 1 is a cross-sectional view showing a diamond film formed on a substrate according to an embodiment of the present invention.

  A diamond film 2 is formed on the substrate 1 by a CVD method. As the substrate 1, a silicon single crystal substrate, a glass substrate, a quartz substrate or the like having an oxide film formed on the surface can be used. As the CVD method, a plasma CVD method, a thermal CVD method, or the like using a gas containing hydrocarbon, hydrogen, and a nitrogen source gas as a source gas can be used.

  As the hydrocarbon, methane, ethylene, acetylene or the like can be used, and as the nitrogen source gas, nitrogen, ammonia or the like can be used.

The diamond film 2 just formed contains nitrogen of 3 × 10 ¹⁸ cm ⁻³ or more, preferably 5 × 10 ^{18 to} 5 × 10 ¹⁹ cm ⁻³ . Thus, the diamond film 2 containing nitrogen of 3 × 10 ¹⁸ cm ⁻³ or more has a very excellent flatness with a surface flatness of less than 50 nm. When the nitrogen content is less than 3 × 10 ¹⁸ cm ⁻³ , the surface of the diamond film 2 is inferior in flatness, and the resistivity is as high as 50 Ωcm or more, resulting in low conductivity.

A diamond film containing nitrogen of 3 × 10 ¹⁸ cm ⁻³ or more can be obtained by using a source gas containing 0.5% or more of a nitrogen source gas together with hydrocarbons and hydrogen in a CVD method. In particular, a diamond film containing nitrogen of 3 × 10 ¹⁸ cm ⁻³ or more can be obtained more reliably by a plasma CVD method using microwave plasma of 1 kW or more.

  Thus, by adding a predetermined amount of nitrogen source gas to the source gas in CVD, CN and C2 (dimer) in the reaction system increase, and their generation density increases, resulting in crystal grains. A diamond film having a small diameter and high surface smoothness can be obtained.

  FIG. 2 is a cross-sectional view showing a method of manufacturing an electrochemical device according to another embodiment of the present invention in the order of steps.

  First, as shown in FIG. 2A, a diamond film 13 is formed by a CVD method on a substrate 11 having an oxide film 12 formed on the surface. The film forming conditions and the like of the diamond film 13 are the same as in the above embodiment.

  Next, as shown in FIG. 2B, an inorganic resist film 14 is formed on the diamond film 13, an organic resist layer is formed on the inorganic resist layer 13, and then patterned by lithography to form an organic resist pattern 15. Form. Examples of the inorganic resist include metal, silicon, or a compound thereof. Specific examples thereof include silicon nitride, chromium nitride, silicon nitride oxide, silicon oxide, and chromium.

  Next, as shown in FIG. 2C, the inorganic resist layer 14 is etched using the organic resist pattern 15 as an etching mask to form an inorganic resist pattern 16. For the etching of the inorganic resist layer 14, for example, reactive ion etching (RIE) can be used. Since the inorganic resist layer 14 has good surface flatness, fine processing by etching can be accurately performed.

Thereafter, as shown in FIG. 2D, the diamond film 13 is etched by dry etching with an etching gas composed of an oxygen-based gas using the thus obtained inorganic resist pattern 16 as an etching mask. 17 is formed. As the oxygen-based gas, oxygen (O ₂ ), ozone (O ₃ ), or nitrous oxide (N ₂ O) can be used.

  Finally, as shown in FIG. 2 (e), the inorganic resist pattern 16 is removed by etching, and an electrochemical element having an electrode made of the diamond pattern 17 is obtained.

  The diamond pattern 17 formed in this way has excellent surface flatness, can be finely processed, and has excellent conductivity. By providing this as an electrode, a highly sensitive electrochemical device is provided. Can be obtained at low cost.

  Examples of the present invention will be described below, and the effects of the present invention will be described more specifically.

Example 1
With reference to FIG. 1, the manufacturing method of the diamond film based on one Example of this invention is demonstrated.

  As shown in FIG. 1, a diamond film 2 was formed on a single crystal silicon substrate 1 having a thickness of 525 μm using a microwave plasma CVD apparatus.

The conditions for microwave plasma CVD are as follows.
Source gas: methane (50 sccm), hydrogen (445 sccm),
Nitrogen (5sccm)
Substrate temperature: 820 ° C
Reaction pressure: 80 Torr
MW power: 2.5kW
Film thickness: 1 μm.

  When the diamond film 2 produced as described above was observed with an atomic force microscope (AFM), a crystal grain size of nanometer order could be confirmed. Moreover, the root mean square surface roughness (rms) which measured 10 micrometers square with AFM was 15 nm.

The presence of sp ³ (diamond bond) could be confirmed by electron beam energy loss spectroscopy (EELS).

  Furthermore, as a result of measuring the electrical conductivity of the diamond film 2, a resistivity of several Ω was obtained.

  The diamond film 2 obtained in this example was observed with a scanning electron microscope, and a photograph taken is shown in FIG. From the photograph of FIG. 3, it can be seen that the diamond film particles are very fine and the surface flatness is excellent.

  As a comparative example, when the source gas does not contain nitrogen or 0.1% nitrogen, a diamond film is formed under the same conditions as described above except for the composition of the source gas. FIGS. 4 and 5 show photographs taken and observed by the above method. It can be seen from the photographs in FIGS. 4 and 5 that the diamond film particles are both rough and have poor surface flatness.

  Further, when the root mean square surface roughness (rms) measured by AFM on 10 μm square was measured, it was 45 nm when the source gas did not contain nitrogen, and 63 nm when 0.1% nitrogen was contained. The degree was inferior.

Next, the amount of nitrogen in the diamond film formed by varying the amount of nitrogen in the source gas was measured by SIMS (secondary ion mass spectrometry), and the diamond film (6 samples) of each nitrogen content was measured. The flatness was determined by the root mean square surface roughness (rms) measured by AFM. Moreover, the resistivity (3 samples) of each diamond film was also measured. The results are shown in the table below. In addition, the numerical value range in a table | surface shows the range of the measured value about 6 samples, and flatness shows the range of the measured value about 3 samples, respectively.

From the above table, when the nitrogen content is 3 × 10 ¹⁸ cm ⁻³ or more, the flatness is 35 nm or less and the film resistivity is 50 Ωcm or less, both of which are good, whereas 3 × 10 ¹⁸ cm. ^When it exceeds ⁻³ , the flatness is 60 nm or less, and the film resistivity is 50 Ωcm or more.

Example 2
With reference to FIG. 2, the manufacturing method of the electrochemical element based on the other Example of this invention is demonstrated.

  First, as shown in FIG. 2A, a thermal oxide film 12 having a thickness of 1 μm was formed on a silicon substrate 11 having a thickness of 1 mm, and then a diamond film 13 was formed using a microwave plasma CVD apparatus. . The conditions of microwave plasma CVD are as follows.

Source gas: methane (50 sccm), hydrogen (445 sccm),
Nitrogen (5sccm)
Substrate temperature: 820 ° C
Reaction pressure: 80 Torr
MW power: 2.5kW
Film thickness: 1 μm.

  The diamond film produced as described above could be confirmed to have a nanometer order crystal grain size with an atomic force microscope (AFM). The root mean square roughness (rms) measured by AFM on 10 μm square was 15 nm.

The presence of sp ³ (diamond bond) could be confirmed by electron beam energy loss spectroscopy (EELS).

  As a result of measuring the electrical conductivity of the film, a resistivity of several Ωcm was obtained.

  Next, as shown in FIG. 2B, a silicon nitride film was formed as a hard mask layer 14 using a high-frequency plasma CVD apparatus using a mixed gas of silane, ammonia and hydrogen.

  The conditions for high-frequency plasma CVD are as follows.

Source gas: Silane (flow rate 5 sccm), ammonia (flow rate 20 sccm), hydrogen (flow rate 175 sccm)
Substrate temperature: 250 ° C
Reaction pressure: 1 Torr
RF power: 180W.

Film thickness: 0.5μm
Next, a photoresist (OFPR manufactured by Tokyo Ohka Kogyo Co., Ltd.) was applied to a thickness of 1.2 μm, and then exposed and developed with g-line to form a photoresist pattern 15 (line width 5 μm).

Next, as shown in FIG. 2C, using the photoresist pattern 15 as a mask, the silicon nitride film as the hard mask layer 14 is processed by RIE using C ₂ F ₆ and hydrogen gas as etching gases, A hard mask pattern 16 was obtained.

  The conditions for RIE are as follows.

Etching gas: C ₂ F ₆ (flow rate 32 sccm), hydrogen (flow rate 3 sccm)
Substrate temperature: room temperature Reaction pressure: 0.03 Torr
RF power: 300W.

  Subsequently, as shown in FIG. 2D, the diamond film 13 is processed by RIE using oxygen gas as a main component by using the hard mask pattern 16 made of silicon nitride as a mask, and the electrochemical element terminal portion 17 is formed. Obtained.

  The conditions for RIE are as follows.

Source gas: O ₂ (flow rate 100 sccm)
Substrate temperature: room temperature Reaction pressure: 0.03 Torr
RF power: 300W.

  Finally, as shown in FIG. 2E, the hard mask pattern 16 was peeled off by etching to obtain an electrochemical element.

  This electrochemical element was able to measure a wide range of substances to be measured, showed a high S / N ratio, and was able to achieve higher sensitivity.

    The diamond film and the manufacturing method thereof of the present invention can be widely used for forming electrodes and the like in various electronic devices. Moreover, the electrochemical device and the manufacturing method thereof of the present invention can be widely applied to various sensors.

It is sectional drawing explaining the manufacturing method of the diamond film which concerns on one Embodiment of this invention. It is sectional drawing which shows the manufacturing method of the electrochemical element which concerns on other embodiment of this invention in order of a process. 2 is a scanning electron micrograph of the diamond film obtained in Example 1. FIG. It is a scanning electron micrograph figure of the diamond film obtained by the comparative example. It is a scanning electron micrograph figure of the diamond film obtained by the comparative example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1,11 ... Base | substrate, 2,13 ... Diamond film, 12 ... Silicon oxide film, 14 ... Inorganic resist film, 15 ... Organic resist pattern, 16 ... Inorganic resist pattern, 17 ... Diamond pattern.

Claims (8)

A diamond film synthesized on a substrate, wherein the diamond film contains nitrogen of 3 × 10 ¹⁸ cm ⁻³ or more.   The diamond film according to claim 1, wherein the diamond film has a surface flatness of less than 50 nm.   The diamond film according to claim 1 or 2, wherein the base is one selected from the group consisting of a silicon substrate, a quartz substrate, a ceramic substrate, and a metal substrate.   A method for producing a diamond film, comprising forming a film on a substrate by a CVD method using a source gas containing hydrocarbon, hydrogen, and a nitrogen source gas of 0.5% or more.   The method for producing a diamond film according to claim 4, wherein the CVD method is a plasma CVD method performed using microwave plasma of 1 kW or more. An electrochemical device comprising a pair of electrodes or more and detecting and measuring the type and / or concentration of a substance to be measured using an oxidation-reduction reaction on the electrode surface, wherein at least one surface of the electrode is An electrochemical element comprising a diamond film containing nitrogen of 3 × 10 ¹⁸ cm ⁻³ or more.   A method for producing an electrochemical device comprising a pair of electrodes or more and detecting and measuring the type and / or concentration of a substance to be measured using an oxidation-reduction reaction on the electrode surface, wherein at least one of the electrodes A method for producing an electrochemical element, comprising a step of forming a diamond film on a surface by a plasma CVD method using a source gas containing hydrocarbon, hydrogen, and a nitrogen source gas of 0.5% or more .   8. The electricity according to claim 7, further comprising a step of patterning the diamond film into an arbitrary shape by a lithography method or an electron beam lithography method following the step of forming the diamond film on the substrate. Chemical element manufacturing method.

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