JP2022123684A - Electrode and manufacturing method of electrode - Google Patents

Abstract

To provide an electrode including a diamond part that is easily processed, high in processing yield and has high reliability.SOLUTION: The electrode includes a support formed of a material other than diamond, and a diamond part supported on a supporting surface which is one of surfaces included in the support. The diamond part is composed of a plurality of granular diamond crystals, and part of the supporting surface is exposed.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to electrodes and methods of making electrodes.

In recent years, it has been proposed to use an electrode having a diamond film as a working electrode of an electrochemical sensor (see, for example, Patent Documents 1 and 2). Diamond, which has conductivity, has a wide potential window and a small background current, so that various substances such as uric acid can be electrochemically detected with high sensitivity. For this reason, diamond, which has conductivity, is attracting attention as a material for forming a working electrode.

JP 2007-292717 A JP 2013-208259 A

However, since diamond is a material with high hardness, it is difficult to form an electrode having a diamond film, and there are problems such as a low processing yield. An object of the present disclosure is to provide an electrode having a diamond portion that is easy to process, has a high processing yield, and is highly reliable.

According to one aspect of the present disclosure,
a support made of a material other than diamond;
a diamond portion supported on a support surface that is at least one of the surfaces of the support;
The diamond part is composed of a plurality of granular diamond crystals,
Electrodes and methods of making the same are provided wherein a portion of the support surface is exposed.

According to the present disclosure, it is possible to provide an electrode having a diamond portion that is easy to process, has a high processing yield, and is highly reliable.

FIG. 2 is a longitudinal cross-sectional view of an electrode according to one aspect of the present disclosure; 1 is a schematic plan view of an electrode according to an aspect of the present disclosure as seen from the top (diamond part side); FIG. 1 is a schematic diagram of a vapor phase growth apparatus used for growing diamond crystals; FIG. (a) is a diagram showing a cross-sectional structure of a laminated body (laminated wafer) of a diamond part and a substrate, and (b) is a cross-sectional view showing a state in which a concave groove is formed on the back surface of the laminated body shown in FIG. 4(a). It is a figure and (c) is a schematic diagram which shows a mode that a support body is fracture|ruptured along a concave groove|channel, and a working electrode is obtained. FIG. 10 is a diagram showing evaluation results of sample 1; FIG. 10 is a diagram showing evaluation results of sample 2; FIG. 10 is a diagram showing evaluation results of sample 3; FIG. 10 is a diagram showing evaluation results of sample 4; FIG. 10 is a diagram showing evaluation results of sample 5; FIG. 10 is a diagram showing evaluation results of sample 6; FIG. 10 is a diagram showing evaluation results of sample 7; FIG. 10 is a diagram showing evaluation results of sample 8; 1 is a diagram showing an example of a perspective view of an electrochemical sensor using an electrode according to one aspect of the present disclosure as a working electrode; FIG.

<One aspect of the present disclosure>
One aspect of the present disclosure will be described below with reference to FIGS. 1 and 2. FIG.

The electrode according to this aspect can be suitably used as a working electrode in electrochemical measurements. For example, the electrode according to this aspect can be suitably used as a working electrode of an electrochemical sensor that measures the concentration of a specific component contained in a test solution (electrolyte) by a two-electrode method or a three-electrode method.

As shown in FIG. 1, the electrode 10 is configured as a laminate having a diamond portion 11 and a support 12 that supports the diamond portion 11 . The electrode 10 having the diamond portion 11 is sometimes called a diamond electrode. When the electrode 10 is used as a working electrode of an electrochemical sensor, the diamond part 11 causes an electrochemical reaction of a specific component (predetermined reactive species) in the sample liquid on the surface. For example, in a sensor provided with an electrode group including the electrode 10 and a counter electrode, when urine as a sample liquid is supplied to the sensor, a predetermined voltage is applied to the electrode group while the urine adheres to the electrode group. Then, the diamond portion 11 causes an oxidation-reduction reaction of uric acid on its surface.

Further, the outer shape of the electrode 10 is formed in a rectangular shape, for example, a square shape in plan view. That is, the electrode 10 is formed in a chip shape (see FIG. 2). The planar area of the electrode 10 can be, for example, 25 mm ² or less. From the viewpoint of manufacturing the chip-shaped electrode 10, the planar area of the electrode 10 is preferably 1 mm ² or more, for example. If the electrode 10 has a plane area of 1 mm ² or more, it can be manufactured easily with high precision and stability by a method using breaking, which will be described later. Further, when the planar area of the electrode 10 is 1 mm ² or more, it is possible to suppress deterioration in the handling property and the mounting stability of the electrode 10 .

The diamond portion 11 is supported (provided) on at least one of the surfaces of the support 12 . Below, the surface of the support 12 that supports the diamond portion 11 is also referred to as a support surface 12s.

As shown in FIG. 2, the diamond portion 11 is composed of a plurality of granular crystals made of diamond, that is, a plurality of granular diamond crystals. The diamond portion 11 may be composed of a plurality of granular crystals made of diamond-like carbon (DLC), that is, a plurality of granular DLC crystals. In the following, the granular diamond crystals and the granular DLC crystals are also collectively referred to as "granular crystals 11a". The diamond part 11 is formed by, for example, a hot filament (hot filament) CVD method using a tungsten filament, a chemical vapor deposition (CVD) method such as a plasma CVD method, or a physical vapor deposition (CVD) method such as an ion beam method or an ionization deposition method. It can be grown (synthesized) using physical vapor deposition (PVD method) or the like. Diamond portion 11 is preferably of p-type. The diamond portion 11 contains an element (dopant) such as boron (B) at a concentration of, for example, 1×10 ¹⁹ cm ⁻³ or more and 1×10 ²² cm ⁻³ or less, preferably 1×10 ²⁰ cm ⁻³ or more and 5×10 ²¹ cm. The diamond portion 11 can be made p-type by containing it at a concentration of ⁻³ or less. That is, it is preferable that the diamond portion 11 is composed of granular crystals 11a containing the B element within the predetermined range. The concentration of B in the diamond portion 11 can be measured by secondary ion mass spectrometry (SIMS), for example.

Since the diamond part 11 is not a continuous film made of diamond (or DLC) (hereinafter also referred to as a diamond film) but is composed of a plurality of granular crystals 11a, the diamond part 11 has gaps or spaces between the granular crystals 11a. (Hereinafter, these are collectively also simply referred to as “gap”).

Since the very hard (high-hardness) diamond portion 11 has a gap, the diamond portion 11 can be separated at the gap between the granular crystals 11a. For example, only by breaking (breaking) the support 12 of the laminate of the diamond part 11 and the support 12 (that is, the laminated wafer 20 described later) before forming the electrode 10, the chip-shaped electrode 10 can be stabilized with high accuracy. can be obtained by In this manner, the diamond portion 11 having the gap can improve the processing yield and processing accuracy of the electrode 10 . Moreover, since the size of the electrode 10 can be reduced, the productivity of the electrode 10 can be improved.

Further, when there is a difference between the thermal expansion coefficient of diamond (or DLC) and the thermal expansion coefficient of the support 12, the difference in the amount of thermal contraction between the diamond part 11 and the support 12 causes the support 12 to A tensile stress or a compressive stress may be applied in the in-plane direction. Since the diamond part 11 has a gap, even if there is a difference between the thermal expansion coefficient of the diamond and the thermal expansion coefficient of the support 12, the stress generated due to the difference in the thermal expansion coefficients can be suppressed by the above gap. can be relieved by . As a result, it is possible to prevent the diamond portion 11 (granular crystal 11a) from peeling off from the support 12 (support surface 12s). As a result, it is possible to avoid reduction in the diamond portion 11 that contributes to sensing, and avoid deterioration in the sensitivity of the electrode 10 . As a result, it becomes possible to improve the reliability of the electrode 10 and the reliability of the sensor having the electrode 10 .

In addition, by alleviating the stress caused by the above-described difference in thermal expansion coefficient, the laminate (later-described laminated wafer 20) of the diamond part 11 and the support 12 before being formed into the electrode 10 is less likely to warp. Also, the residual stress in the diamond part 11 can be reduced, preferably the residual stress can be eliminated. As a result, the electrode 10 can be easily obtained from the laminated wafer 20 with high accuracy and stability. That is, the machining accuracy, machining yield, and productivity of the electrode 10 can be further improved.

The diamond portion 11 is provided so as to partially expose the support surface 12s without covering the entire support surface 12s. For example, the ratio of the projected area of the granular crystals 11a onto the support surface 12s to the plane area of the support surface 12s is 15% or more and 90% or less, preferably 30% or more and 75% or less. In this specification, the ratio of the projected area of the granular crystals 11a onto the supporting surface 12s to the planar area of the supporting surface 12s (=(projected area of the granular crystals 11a/planar area of the supporting surface 12s)×100) is referred to as "coverage". Also called That is, the coverage of the support surface 12s with the diamond portion 11 is, for example, 15% or more and 90% or less, preferably 30% or more and 75% or less.

With a coverage of 15% or more, the surface area of the diamond portion 11 can be made greater than or equal to a predetermined value. Thereby, the electrode 10 can be suitably used as a working electrode of an electrochemical sensor.

In addition, the total surface area of the diamond portion 11 that can contribute to sensing (hereinafter also referred to as the surface area of the diamond portion 11) is made larger than the plane area of the support surface 12s by the coverage being 15% or more and 90% or less. can be done. Moreover, the surface area of the diamond part 11 can be made larger than when the coverage is over 90% or when the diamond part 11 is composed of a diamond film. This makes it possible to improve the sensitivity of the electrode 10, and to improve the accuracy of electrochemical measurement using a sensor using the electrode 10 as a working electrode. For example, when the concentration of uric acid in the test solution is measured by cyclic voltammetry using a sensor having the electrode 10, the oxidation current peak (value) observed in the resulting cyclic voltammogram indicates that the coverage is It is higher than when it exceeds 90% and when the diamond portion 11 is composed of a diamond film. As a result, it is possible to more accurately measure the concentration of uric acid in the test fluid.

In addition, since the coverage is 90% or less, it is possible to reliably obtain the diamond portion 11 having a gap. As a result, the processing yield and processing accuracy of the electrode 10 can be reliably improved. In addition, the effect of relieving the stress caused by the above-described difference in thermal expansion coefficient (hereinafter also referred to as "stress relaxation effect") can be easily obtained, and it is possible to reliably prevent the granular crystals 11a from peeling off. Become.

In addition, when the coverage is 75% or less, it becomes possible to obtain the diamond portion 11 having a sufficient gap. Thereby, the processing yield and processing accuracy of the electrode 10 can be further improved. Moreover, the stress relaxation effect described above can be reliably obtained, and it is possible to more reliably prevent the granular crystals 11a from peeling off. As a result, it becomes possible to further improve the accuracy of the electrochemical measurement.

Moreover, the surface area of the diamond portion 11 can be increased by setting the coverage to 30% or more and 75% or less. As a result, the sensitivity of the electrode 10 can be further enhanced, and the accuracy of electrochemical measurement can be further enhanced.

The average grain size of the plurality of granular crystals 11a can be, for example, 60 nm or more and 150 nm or less, preferably 75 nm or more and 125 nm or less. The average grain size here is the average grain size in the cross section of the diamond part 11 in the planar direction of the support surface 12s of the support 12. As shown in FIG. The average grain size of the granular crystals 11a can be obtained by image analysis of the field of view of an image (eg, SEM image) taken with a scanning electron microscope or an image (eg, TEM image) taken with a transmission electron microscope. Specifically, first, an SEM image and a TEM image are acquired, and the grain size distribution of the granular crystals 11a is measured based on the SEM image and the TEM image. Subsequently, individual particles are extracted using image analysis software (eg, ScionImage manufactured by Scion Corporation), and the extracted particles are binarized to calculate the area (S) of each particle. Then, the particle size (D) of each particle is calculated as the diameter of a circle having the same area (D=2√(S/π)). Next, the particle size distribution obtained above is processed by data analysis software (eg, Origin by OriginLab, Mathchad by Parametric Technology, etc.) to calculate the average particle size.

When the average grain size is, for example, 60 nm or more, it is possible to avoid manifestation of adverse effects caused by the grain boundaries between the granular crystals 11a. For example, even if there is a region (localized region, dense region) where the granular crystals 11a are densely present on the support surface 12s, an increase in dark current during electrochemical measurement can be avoided, and the sensor having the electrode 10 It is possible to avoid an increase in the noise level in The dark current here means that the current value generated by the oxidation-reduction reaction is not measured while a predetermined voltage is applied to the electrode group (working electrode, counter electrode, reference electrode) of the sensor. is the current that flows between the working electrode and the counter electrode. Further, for example, even if there is a region (non-dense region) where the granular crystals 11a are sparsely present on the support surface 12s, a decrease in the output current (detection output signal) can be avoided in the sensor having the electrode 10, A decrease in the S/N ratio can be avoided. By avoiding manifestation of adverse effects caused by the grain boundaries between the granular crystals 11a in this way, it is possible to further improve the reliability of the electrode 10 and the accuracy of electrochemical measurement.

In addition, when the average particle size is, for example, 60 nm or more, the coverage rate can be easily increased to 15% or more.

When the average grain size is 75 nm or more, it is possible to reliably avoid manifestation of adverse effects caused by grain boundaries between granular crystals 11a. Also, the coverage rate can be easily increased to 30% or more.

When the average grain size is 150 nm or less, it is possible to reliably obtain the diamond portion 11 having gaps. Also, the coverage rate can be easily reduced to 90% or less.

When the average grain size is 125 nm or less, it becomes possible to reliably obtain the diamond portion 11 having a sufficient gap. Also, the coverage rate can be easily reduced to 75% or less.

The granular crystals 11a are randomly present on the support surface 12s. "The granular crystals 11a are randomly present" means that the plurality of granular crystals 11a are present on the support surface 12s without any regularity and without being extremely localized (unevenly distributed). "A plurality of granular crystals 11a exist without regularity" includes cases in which one granular crystal 11a exists independently, cases in which a plurality of granular crystals 11a exist in contact (in a row), and both of these cases. includes the case of Thus, it is preferable that the support surface 12s does not have a region where the granular crystals 11a are present extremely densely or coarsely. As a result, variations in sensitivity within one electrode 10 can be avoided, that is, the sensitivity of the electrode 10 can be made uniform within the plane. As a result, for example, even if a small amount of sample liquid is supplied to the sensor having the electrode 10 during electrochemical measurement, it is possible to perform accurate electrochemical measurement.

The support 12 is formed using a material other than diamond (heterogeneous material). The support 12 can be constructed using a conductive material. For example, the support 12 can be a support configured using Si alone or a silicon compound, that is, a conductive support containing silicon (Si). Specifically, the support 12 can be configured by a silicon substrate (Si substrate). As the Si substrate, any one of a single crystal Si substrate, a polycrystalline Si substrate, and a silicon carbide substrate (SiC substrate) can be used.

Like the diamond portion 11, the support 12 is preferably p-type, and preferably contains an element such as boron (B) at a predetermined concentration. The support 12 contains B at a concentration of, for example, 5×10 ¹⁸ cm ⁻³ or more and 1.5×10 ²⁰ cm ⁻³ or less, preferably 5×10 ¹⁸ cm ⁻³ or more and 1.2×10 ²⁰ cm ⁻³ or less. can be contained at a concentration of When the concentration of B in the support 12 is within the above range, it is possible to reduce the specific resistance of the support 12 while avoiding a decrease in manufacturing yield and performance deterioration of the support 12 .

The thickness of the support 12 can be, for example, 350 μm or more. As a result, a Si substrate such as a commercially available single-crystal Si substrate or a polycrystalline Si substrate having a diameter of 6 inches or 8 inches can be used as the support 12 as it is without adjusting the thickness by back lapping. becomes possible. As a result, it becomes possible to improve the productivity of the electrode 10 and reduce the manufacturing cost. Although the upper limit of the thickness of the support 12 is not particularly limited, the thickness of a Si substrate generally available on the market at present is about 775 μm for a single crystal Si substrate with a diameter of 12 inches. Therefore, the upper limit of the thickness of the support 12 in the current technology can be set to about 775 μm, for example.

As described above, the diamond portion 11 is provided so as to partially expose the support surface 12s. Therefore, when a predetermined voltage is applied to the support surface 12s, uric acid is oxidized on a region of the support surface 12s that is not in contact with the granular crystals 11a (hereinafter also referred to as “exposed region of the support surface 12s”). It is preferably constructed so as not to cause a reductive reaction. For example, when a predetermined voltage is applied, the exposed region of the supporting surface 12s is subjected to a treatment (inactivation treatment) that suppresses the occurrence of oxidation-reduction reaction of uric acid on the exposed region of the supporting surface 12s. What is preferably done is that the exposed areas of the support surface 12s are passivated.

The inventors of the present application found that even if the entire surface of the support surface 12s is not covered with the diamond portion 11, if the exposed region of the support surface 12s is inactivated, the sensor having the electrode 10 can be used when measuring the uric acid concentration. It has been confirmed that in the voltage range applied to , it is possible to avoid oxidation-reduction reaction of uric acid on the exposed area of the support surface 12s. The voltage range applied when measuring the uric acid concentration is exemplified by a voltage range that includes a range of more than 0 V and 1 V or less, preferably a voltage range that includes a range of 0.4 V or more and 0.9 V or less.

Passivation of the exposed areas of the support surface 12s can be accomplished by, for example, oxidizing or nitriding the exposed areas of the support surface 12s. By oxidizing or nitriding the exposed region of the support surface 12s, at least the surface layer portion of the support 12 containing Si is oxidized or nitrided, and an insulating film (insulating film) 14 is formed on the exposed region of the support surface 12s. It will be done. In this case, the insulating film 14 is a film containing silicon oxide (SiO _x ) or a film containing silicon nitride (SiN). Thus, the exposed regions of the supporting surface 12s are inactivated by forming the insulating film 14 on the exposed regions. The inactivation of the exposed region of the support surface 12s may be performed on at least the surface layer portion of the exposed region of the support surface 12s.

The insulating film 14 covers the entire exposed region of the support surface 12s without exposing the exposed region of the support surface 12s. As a result, even if the sample liquid comes into contact with the exposed region of the support surface 12s, it is possible to reliably avoid the oxidation-reduction reaction of uric acid in the exposed region of the support surface 12s during the electrochemical measurement. Become.

The thickness of the insulating film 14 (for example, the thickness of the oxidized or nitrided surface layer of the support 12) can be, for example, 1 nm or more, preferably 2 nm or more. If the thickness of the insulating film 14 is 1 nm or more, the entire exposed region of the support surface 12s can be covered. By setting the thickness of the insulating film 14 to 2 nm or more, it is possible to reliably cover the entire exposed region of the support surface 12s. If the thickness of the insulating film 14 is excessively thick, the conductive area of the support 12 is reduced. Therefore, it is preferable that the thickness of the insulating film 14 be as thin as possible so as to cover the entire exposed region of the supporting surface 12s.

By inactivating the exposed region of the support surface 12s in this manner, the electrode 10 causes an oxidation-reduction reaction of uric acid on the surface of the diamond portion 11 when a predetermined voltage is applied, and the support surface 12s is oxidized. It is configured not to cause redox reaction of uric acid on the exposed area.

(3) Method for Manufacturing Electrode A method for manufacturing the electrode 10 of this embodiment will be described mainly with reference to FIGS. 3 and 4. FIG.

In the method for manufacturing the electrode 10 of this aspect,
a step of performing a predetermined seeding process or scratching process on the surface of the support 12 that will be the support surface 12s (step A);
a step of providing the diamond portion 11 on the support surface 12s of the support 12 by growing a plurality of granular crystals 11a so that a portion of the support surface 12s is exposed (step B);
and passivating the exposed areas of the support surface 12s (step C).

(Step A)
As the support 12, a substrate having conductivity, for example, a Si substrate having a circular outer shape in plan view is prepared. Then, of the two main surfaces of the support 12, the surface that serves as the support surface 12s is subjected to a seeding process or a scratching process. The seeding treatment includes, for example, applying a solution (dispersion liquid) in which diamond particles (preferably diamond nanoparticles) of several nanometers to several tens of micrometers are dispersed on the support surface 12s, or immersing the support 12 in the dispersion liquid. It is a process of attaching diamond grains (seeds) to the support surface 12s. The scratching process is a process of scratching the support surface 12s using diamond abrasive grains (diamond powder) of about several μm.

Granular crystals 11a grown in step B described later grow from diamond grains adhering to the support surface 12s and scratches on the support surface 12s as nuclei. Therefore, by controlling (adjusting) the seeding treatment or the scratching treatment, it is possible to randomly grow a plurality of granular crystals 11a on the support surface 12s in step B described later.

(Step B)
After step A is completed, step B is performed. Specifically, diamond crystals are grown on the support surface 12s of the support 12 by, for example, a hot filament CVD method using a tungsten filament to provide the diamond portion 11 .

Diamond crystal growth can be performed using, for example, a hot filament CVD apparatus 300 as shown in FIG. A hot-filament CVD apparatus 300 is made of a heat-resistant material such as quartz, and includes an airtight container 303 in which a growth chamber 301 is constructed. A susceptor 308 that holds the support 12 is provided in the growth chamber 301 . On the side wall of the airtight container 303, a gas supply pipe 332a for supplying nitrogen (N ₂ ) gas into the growth chamber 301, a gas supply pipe 332b for supplying hydrogen (H ₂ ) gas, and a gas supply pipe 332c for supplying methane (CH ₄ ) gas or ethane (C ₂ H ₆ ) gas, and trimethyl boron (B(CH ₃ ) ₃ , abbreviation: TMB) gas as boron (B)-containing gas, trimethyl A gas supply pipe 332d for supplying borate (B(OCH ₃ ) ₃ ) gas, triethyl borate (B(C ₂ H ₅ O) ₃ ) gas, or diborane (B ₂ H ₆ ) gas is connected. Gas supply pipes 332a to 332d are provided with flow rate controllers 341a to 341d and valves 343a to 343d, respectively, from the upstream side of the gas flow. Nozzles 349a to 349d for supplying the gases supplied from the gas supply pipes 332a to 332d into the growth chamber 301 are connected to the downstream ends of the gas supply pipes 332a to 332d, respectively. Another side wall of the airtight container 303 is provided with an exhaust pipe 330 for exhausting the inside of the growth chamber 301 . A pump 331 is provided in the exhaust pipe 330 . A temperature sensor 309 for measuring the temperature inside the growth chamber 301 is provided inside the airtight container 303 . A tungsten filament 310 and a pair of electrodes (for example, molybdenum (Mo) electrodes) 311a and 311b for heating the tungsten filament 310 are provided in the airtight container 303, respectively. Each member provided in the hot filament CVD apparatus 300 is connected to a controller 380 configured as a computer, and a processing procedure and processing conditions to be described later are controlled by a program executed on the controller 380. .

Diamond crystals can be grown by using the hot filament CVD apparatus described above, for example, according to the following procedure. First, the support 12 is loaded (carried) into the airtight container 303 and held on the susceptor 308 . Then, H ₂ gas is supplied into the growth chamber 301 while evacuating the growth chamber 301 . Also, a current is passed between the electrodes 311a and 311b to start heating the tungsten filament 310 . As the tungsten filament 310 is heated, the support 12 held on the susceptor 308 is also heated. When the tungsten filament 310 reaches a desired temperature, the inside of the growth chamber 301 reaches a desired pressure, and the atmosphere inside the growth chamber 301 reaches a desired atmosphere, a C-containing gas ₍ e.g., CH4 gas) is introduced into the growth chamber 301. , B-containing gas (for example, TMB gas). The CH ₄ gas and TMB gas supplied into the growth chamber 301 are decomposed (thermally decomposed) when passing through the tungsten filament 310 heated to a high temperature to generate active species such as methyl radicals (CH ₃ ^* ). be done. The active species and the like are supplied onto the support 12 to grow diamond crystals.

The following conditions are exemplified as conditions for growing diamond crystals.
Substrate temperature: 600° C. to 1000° C., preferably 650° C. to 800° C. Filament temperature: 1800° C. to 2500° C., preferably 2000° C. to 2200° C. Growth chamber pressure: 5 Torr to 50 Torr, preferably 10 Torr to 35 Torr Ratio of partial pressure of TMB gas to CH4 gas ₍ TMB/ _CH4 ): 0.003% or _more and 0.8% or less Ratio of CH4 gas to H2 gas ₍ CH4/H2): ₂ % or _more5 % or less Growth time: 30 minutes or more and 120 minutes or less, preferably 60 minutes or more and 100 minutes or less

As a result, a laminate (laminated wafer 20) of the support 12 and the diamond portion 11 is produced as shown in the schematic cross-sectional view of FIG. 4(a).

By growing the diamond crystals under the conditions described above, the diamond portion 11 can be composed of a plurality of granular crystals 11a. Also, the B concentration in the diamond portion 11 can be set to, for example, 1×10 ¹⁹ cm ⁻³ or more and 1×10 ²² cm ⁻³ or less.

In particular, by setting the time (growth time) for growing the granular crystals 11a to 30 minutes or more and 120 minutes or less, a part of the support surface 12s is exposed (so that the entire support surface 12s is not covered). A diamond portion 11 may be provided.

Further, by setting the growth time to 30 minutes or more and 120 minutes or less, the coverage of the support surface 12s with the diamond portion 11 can be made 15% or more and 90% or less, and the average grain size of the granular crystals 11a can be made 60 nm or more and 150 nm or less. It becomes easier to: Further, by setting the growth time to 60 minutes or more and 100 minutes or less, it becomes easy to set the coverage ratio to 30% or more to 75% or less and the average grain size of the granular crystals 11a to 75 nm or more and 125 nm or less.

Further, as described above, in step A, the supporting surface 12s is subjected to a predetermined seeding process or scratching process. Therefore, by growing the diamond crystals under the conditions described above, the granular crystals 11a grow randomly on the support surface 12s.

(Step C)
After step B is completed, step C is performed. In this step, regions of the support surface 12s that are not in contact with the granular crystals 11a (exposed regions of the support surface 12s) are inactivated. Specifically, the laminated wafer 20 with a part of the supporting surface 12s exposed is annealed in an oxygen-containing atmosphere (O-containing atmosphere) or a nitrogen-containing atmosphere (N-containing atmosphere).

The following conditions are exemplified as annealing conditions.
Annealing atmosphere: _O2 gas, air, or _N2 gas Annealing temperature: 60°C to 200°C, preferably 70°C to 140°C Annealing time: 5 minutes to 180 minutes, preferably 60 minutes to 120 minutes

By performing annealing under the above conditions, a thermal oxide film (SiO _x film) or a nitride film (SiN film) as the insulating film 14 can be formed on the entire exposed region of the support surface 12s. At least the surface layer can be inactivated.

In this step, instead of the annealing described above, the laminated wafer 20 may be irradiated with ultraviolet light in an O-containing atmosphere using, for example, a mercury lamp.

The following conditions are exemplified as conditions for irradiation with ultraviolet light.
Irradiation atmosphere: O ₂ gas or air Irradiation temperature: room temperature (25-28°C, for example 27°C)
Irradiation time: 5 minutes to 30 minutes, preferably 10 minutes to 20 minutes

By irradiating the ultraviolet light under the above conditions, the exposed region of the supporting surface 12s can be oxidized, and an ozone oxide film can be formed as the insulating film 14 on the entire exposed region of the supporting surface 12s. can be inactivated at least at the surface layer.

Also, in this step, instead of the above-described annealing or ultraviolet light irradiation, the laminated wafer 20 may be left in a clean atmosphere such as in a clean bench to form a natural oxide film.

The following conditions are exemplified as the conditions for forming the natural oxide film.
Atmosphere for natural oxide film formation: Atmosphere with a humidity of 50% or more Natural oxide film formation temperature: Room temperature (25°C) or higher Natural oxide film formation time: 1000 minutes or more

By leaving the laminated wafer 20 in the atmosphere under the above conditions, the exposed region of the support surface 12s is also oxidized to form a natural oxide film as the insulating film 14 on the exposed region of the support surface 12s. Exposed areas can be passivated. However, the above-described annealing or ultraviolet light irradiation is preferable from the viewpoint of being able to reliably cover the entire exposed region of the support surface 12s with the insulating film 14, and the like.

(Molding)
After step C is completed, the laminated wafer 20 is molded to obtain the electrode 10 having a predetermined shape (for example, a chip shape).

Specifically, as shown in FIG. 4B, concave grooves 21 (for example, scribed grooves) are formed from the rear surface of the laminated wafer 20 (the surface opposite to the support surface 12s). The recessed grooves 21 can be formed using, for example, laser processing methods such as laser scribing and laser dicing, machining methods, and known techniques such as etching. The concave groove 21 is preferably formed so as not to penetrate the support 12 in the thickness direction, that is, so as not to reach the diamond portion 11 . The concave groove 21 is preferably formed so that the thickness of the thinnest part of the support 12 is, for example, 10 μm or more and 80 μm or less. By providing the recessed groove 21 in this way, it is possible to suppress deterioration of the diamond part 11 and further avoid deterioration of the sensitivity of the electrode 10 . Note that the deterioration of the diamond part 11 means, for example, that sp ³ bonds of the granular crystals 11a are changed to sp ² bonds, that is, they are graphitized.

Subsequently, as shown in FIG. 4(c), the support 12 is broken along the concave groove 21. Then, as shown in FIG. At this time, it is preferable to bend the diamond portion 11 outward along the concave groove 21 to break the support 12 .

As described above, the diamond portion 11 is composed of a plurality of granular crystals 11a, and gaps exist between the granular crystals 11a. Therefore, since the diamond portions 11 are separated by the gaps between the granular crystals 11a, the electrode chip 10 having the diamond portion 11 and the support 12 can be obtained simply by breaking the support 12. FIG. In this way, since the gaps exist between the granular crystals 11a, even in the case where the diamond portion 11 has a high hardness, the chip-shaped electrode 10 can be stabilized with high accuracy by the above-described technique using fracture. can be obtained easily.

Fractured surfaces are less likely to be formed on the side surfaces of the diamond portion 11 of the electrode 10 obtained by the method using the above-described fracture. That is, the diamond portion 11 has almost no fracture surface, preferably the diamond portion 11 has no fracture surface. In addition, since the diamond portion 11 is not broken by the method using the breakage described above, the diamond portion 11 is less likely to overhang from the support surface 12s. Therefore, the projection image of the diamond portion 11 (granular crystal 11a) onto the support surface 12s is entirely within the support surface 12s. That is, the diamond portion 11 does not have a region overhanging the support surface 12s.

It is also conceivable to form the concave groove 21 from the surface side (diamond portion 11 side) of the laminated wafer 20 . However, since the diamond portion 11 has a high hardness, it is difficult to form the concave groove 21 from the diamond portion 11 side by a laser processing method, a machining method, or the like.

It is also conceivable to form the laminated wafer 20 into a predetermined shape by dry etching or the like to obtain the electrode 10 . However, it is very difficult to form the laminated wafer 20 having the diamond portion 11 of high hardness into a predetermined shape by dry etching or the like. Also, when dry etching is performed, a degraded region may occur in the diamond portion 11 .

(5) Effect According to this aspect, one or more of the following effects can be obtained.

(a) By forming the diamond part 11 with a plurality of granular crystals 11a, the diamond part 11 has gaps between the granular crystals 11a.

As a result, the ease of processing, processing yield, and processing accuracy of the electrode 10 can be improved. For example, even if the diamond portion 11 has a high hardness, the tip-shaped electrode 10 can be obtained easily and stably with high accuracy by the above-described method using breaking. It is also possible to reduce the size (planar area) of the electrode 10 . As a result, it becomes possible to improve the productivity of the electrode 10 and reduce the manufacturing cost.

Moreover, even if there is a difference between the thermal expansion coefficient of the diamond and the thermal expansion coefficient of the support 12, the stress caused by the difference in these thermal expansion coefficients can be alleviated. can be avoided from peeling off from the support surface 12s. As a result, it is possible to avoid reduction in the diamond portion 11 that contributes to sensing, and to avoid deterioration in the sensitivity of the electrode 10 . As a result, it becomes possible to improve the reliability of the electrode 10 and the reliability of the sensor having the electrode 10 .

On the other hand, if the diamond portion 11 is made of a diamond film, the forming process of the electrode 10 is difficult, and the process yield and process accuracy are lowered. Moreover, in this case, the stress caused by the above-described difference in thermal expansion coefficient cannot be relieved, and the diamond film, which is hard and resistant to warping, tends to peel off from the support surface 12s.

(b) By relieving the stress caused by the above-described difference in thermal expansion coefficient, the laminated body (laminated wafer 20) of the diamond portion 11 and the support 12 before being formed into the electrode 10 is less likely to warp. Moreover, it is also possible to reduce the residual stress of the diamond part 11 . As a result, the processing accuracy, processing yield, and productivity of the electrode 10 can be further improved.

(c) Since the diamond portion 11 is provided so that a part of the support surface 12s is exposed, the diamond portion 11 covers the entire support surface 12s (for example, when a diamond film is formed). The growth of the portion 11 can be completed in a short time. As a result, the material cost for forming the diamond portion 11 can be reduced, so the manufacturing cost of the electrode 10 can be reduced. In addition, deposits adhering to the inside of the growth chamber 301 of the hot filament CVD apparatus 300 are reduced, and the number of times of cleaning the inside of the growth chamber 301 can be reduced, so that the productivity can be further improved and the manufacturing cost can be reduced. can be reduced.

(d) The coverage of the support surface 12s by the diamond portion 11 is 15% or more and 90% or less, so that the electrode 10 can be suitably used as a working electrode of an electrochemical sensor, while the diamond portion 11 having a gap is formed. you can get it for sure. As a result, it becomes possible to improve the ease of processing, processing yield, and processing accuracy of the electrode 10 , and to reliably obtain the above-described stress relaxation effect, thereby making it possible to increase the reliability of the electrode 10 . In addition, the surface area of the diamond portion 11 can be made larger than the plane area of the support surface 12s, or can be made larger than when the diamond portion 11 is formed of a diamond film, and the sensitivity of the electrode 10 can be enhanced. It becomes possible.

In addition, when the coverage exceeds 90%, it becomes difficult to obtain the diamond portion 11 having a gap. For this reason, the forming process of the electrode 10 becomes difficult, and the process yield and process accuracy of the electrode 10 may decrease. In addition, it becomes difficult to obtain the above-described stress relaxation effect, and peeling off of the granular crystals 11a cannot be avoided, and the sensitivity and reliability of the electrode 10 may be lowered. If the coverage is less than 15%, the surface area of the diamond portion 11 is too small, and the electrode 10 may not be used as a working electrode of an electrochemical measurement sensor.

(e) Since the average grain size of the granular crystals 11a is 60 nm or more and 150 nm or less, it is possible to avoid manifestation of adverse effects caused by the grain boundaries between the granular crystals 11a, thereby improving the reliability of the electrode 10 and improving the electrochemical measurement performance. Accuracy can be further improved. Moreover, it is also possible to easily obtain the electrode 10 having a coverage of 15% or more and 90% or less.

On the other hand, if the average grain size exceeds 150 nm, the diamond portion 11 may not have a gap, or even if it does have a gap, the gap may be small. For this reason, the ease of processing, processing yield, and processing accuracy of the electrode 10 may decrease, and the stress relaxation effect described above may not be obtained sufficiently. If the average grain size is less than 60 nm, the number of crystal grain boundaries present in the diamond part 11 increases, making it impossible to avoid manifestation of the adverse effects of the grain boundaries. Chemical measurements may be less accurate.

(f) Variation in sensitivity within one electrode 10 can be avoided due to the presence of a plurality of granular crystals 11a randomly on the support surface 12s. As a result, for example, even if a small amount of sample liquid is supplied to the sensor having the electrode 10 during electrochemical measurement, accurate electrochemical measurement can be performed.

(g) A region of the support surface 12s that is not in contact with the granular crystals 11a, that is, the exposed region of the support surface 12s is inactivated, so that uric acid is oxidized on the exposed region of the support surface 12s during electrochemical measurement. Occurrence of a reduction reaction can be avoided. This makes it possible to further improve the accuracy of the electrochemical measurement.

(h) By performing step C described above to inactivate the exposed region of the support surface 12s, it is possible to reliably cover the entire exposed region of the support surface 12s with the insulating film 14 . As a result, it is possible to reliably avoid oxidation-reduction reaction of uric acid on the exposed region of the support surface 12s, and to further improve the accuracy of the electrochemical measurement.

Note that even if step C described above is not intentionally performed, a natural oxide film is normally formed on the exposed region of the support surface 12s. However, in many cases, this natural oxide film cannot reliably cover the entire exposed region of the support surface 12s, and the passivation is often insufficient. On the other hand, in this embodiment, a process (that is, step C) of inactivating the exposed region of the support surface 12s is performed. Thereby, the exposed region of the support surface 12s can be sufficiently inactivated, and the entire exposed region of the support surface 12s can be reliably covered with the insulating film 14 .

<Other aspects>
Aspects of the present disclosure have been specifically described above. However, the present disclosure is not limited to the embodiments described above, and various modifications can be made without departing from the scope of the present disclosure.

For example, a functional film that allows a specific component (for example, only uric acid) to permeate or a functional film that reacts only with this specific component may be provided on the diamond portion 11 . As such a functional membrane, for example, a predetermined surface-decorating membrane such as a membrane containing a predetermined enzyme corresponding to the component to be detected or an ion-exchange membrane may be provided.

Further, for example, in step C, if the exposed region of the support surface 12s can be inactivated, the inactivation treatment is performed using a method other than the above-described annealing, ultraviolet light irradiation, and exposure to clean air. may For example, the deactivation treatment may be performed using various acids, hydrogen peroxide water, water, etc., instead of the above-described annealing, ultraviolet light irradiation, or clean air. As such a method, a method of inactivating the exposed region of the support surface 12s by immersing it in pure water containing oxygen or a solution containing an oxidizing agent to perform chemical etching is conceivable. Further, in step C, the deactivation treatment may be performed by appropriately combining a plurality of methods among the above-described methods such as annealing, ultraviolet light irradiation, exposure to clean air, and chemical etching.

Moreover, in the above-described aspect, step C is performed before molding is performed, but the present invention is not limited to this. For example, step C may be performed after molding.

Moreover, in the above-described aspects, an example in which the sample liquid is urine has been described, but the present invention is not limited to this. The test fluid may be body fluid such as blood, tears, runny nose, saliva, sweat, etc., in addition to urine. Moreover, the test liquid is not limited to that derived from humans, and may be derived from animals. Further, in the above embodiment, an example of electrolyzing uric acid as a specific component contained in the test liquid has been described, but the present invention is not limited to this. If the voltage applied to the sensor having the electrode 10 is within a predetermined voltage range, the concentration of various components (substances) can be measured by appropriately changing the voltage sweep conditions for cyclic voltammetry.

Moreover, in the above embodiment, an example of using the electrode 10 as a working electrode of an electrochemical sensor has been described, but the present invention is not limited to this. For example, it can also be used as an electrode for electrolysis (for example, an electrode for electrolysis of an ozone generator) used in electrolysis or synthesis of compounds, electrolysis of water, or the like.

Experimental results that support the effects of the above-described aspects will be described below.

A circular Si substrate having a size of 6 inches in plan view was prepared as a support, and the surface of the main surface of the Si substrate that was to support the diamond portion (ie, the crystal growth surface) was subjected to a predetermined scratching treatment. rice field. Then, using the hot filament CVD apparatus shown in FIG. 3 and using a tungsten filament as the filament, a diamond crystal is grown on the support surface that has been subjected to the scratching treatment to form a diamond portion, thereby forming a laminate of the Si substrate and the diamond portion. Laminated wafers (Samples 1 to 8) were produced. In preparing each sample, the crystal growth time was adjusted to vary the coverage of the supporting surface with the diamond portion. The growth conditions other than the growth time were the same predetermined conditions within the condition ranges described in the above embodiments. After that, the laminated wafers (Samples 2 to 8) whose coverage was not 100% were annealed in an O-containing atmosphere to perform a predetermined passivation treatment. Annealing conditions were the same predetermined conditions within the condition range described in the above embodiment.

Then, laser light (532 nm, 5 W, 10 kHz, spot diameter 2 μm) was applied to the back surface of the Si substrate of Samples 1 to 8 (the surface opposite to the surface on which the diamond part was provided) using a laser of a galvano optical system. , to form lattice-shaped laser grooves (concave grooves) at a scanning speed of 10 cm/sec. Note that the number of scans of the laser beam was set to 4 times. After that, breaking (breaking) was performed along the laser groove under the conditions of a break pushing amount of 0.1 mm and a breaking speed of 100 mm/s, and a plurality of chips each having a size of 2 mm square were obtained from each of samples 1 to 8. An electrode was produced.

(evaluation)
SEM images of the electrodes fabricated from samples 1-8 were taken. SEM images taken are shown in FIGS. 5 to 12, respectively. The “planar SEM image” in FIGS. 5 to 12 is an SEM image of the electrode taken from the diamond part side, that is, the SEM image of the electrode in the plane direction of the support surface, and the “cross-sectional SEM image” is the electrode 1 is a SEM image of a longitudinal section of the electrode, that is, an SEM image of the electrode in a direction perpendicular to the support surface.

The coverage and average particle size of samples 1 to 8 were measured. The coverage of samples 1 to 8 was calculated by binarizing the obtained planar SEM image and calculating the ratio of the area of the diamond portion (for example, white portion) to the total area of the binarized image. Further, the average particle diameters of samples 1 to 8 were calculated by image analysis of planar SEM images obtained using the method described in the above embodiment. Sample 1 had a coverage of 100% and an average particle size of 220 nm. Sample 2 had a coverage of 98% and an average particle size of 165 nm. Sample 3 had a coverage of 84% and an average particle size of 121 nm. Sample 4 had a coverage of 72% and an average particle size of 115 nm. Sample 5 had a coverage of 66% and an average particle size of 96 nm. Sample 6 had a coverage of 31% and an average particle size of 79 nm. Sample 7 had a coverage of 15% and an average particle size of 62 nm. Sample 8 had a coverage of 1.2% and an average particle size of 45 nm.

Also, using the electrodes prepared from samples 1 to 8 as working electrodes, an electrochemical sensor as shown in FIG. 13 was prepared. Then, using this electrochemical sensor, the uric acid concentration in the test solution was measured by cyclic voltammetry to obtain a cyclic voltammogram. Cyclic voltammetry was performed under the same predetermined conditions within a voltage range including -1100 mV to 1500 mV and a sweep rate of 0.1 V/s to 1 V/s. The obtained cyclic voltammograms (CV) are shown in FIGS. 5 to 12, respectively.

Especially from the cross-sectional SEM image in FIG. 5, it can be confirmed that when the coverage is 100%, the diamond part becomes a continuous film made of diamond, and the diamond part cannot be composed of granular crystals.

Further, from FIG. 6, it can be confirmed that when the coverage is 98%, the diamond portion can be composed of granular crystals, but the diamond portion has almost no gaps or spaces between the granular crystals.

From FIGS. 7 and 11, it can be confirmed that when the coverage is 84% or 15%, the diamond portion is composed of granular crystals and has a predetermined gap or space between the granular crystals. Moreover, it can be confirmed that when the coverage is 84% or 15%, the oxidation current peak in the cyclic voltammogram is higher than when the coverage is 100%. From this, it can be seen that when the coverage is 15% or more and 90% or less, the sensitivity of the electrode can be made higher than when the coverage is more than 90%. That is, it can be seen that the accuracy of electrochemical measurement can be improved more than when the coverage is over 90%.

From FIGS. 8 and 10, it can be confirmed that when the coverage is 72% or 31%, the diamond portion is composed of granular crystals and has sufficient gaps and spaces between the granular crystals. Moreover, it can be confirmed that when the coverage is 72% or 31%, the oxidation current peak in the cyclic voltammogram is higher and sharper than when the coverage is 84% or 15%. From this, it can be seen that when the coverage is 30% or more and 75% or less, the sensitivity of the electrode can be further increased, and the accuracy of electrochemical measurement can be further improved.

From FIG. 9, it can be confirmed that when the coverage is 66%, the diamond portion is composed of granular crystals, and sufficient gaps and spaces are provided between the granular crystals. Moreover, it can be confirmed that when the coverage is 66%, the oxidation current peak in the cyclic voltammogram is higher and sharper than when the coverage is 72% or 31%. From this, it can be seen that when the coverage is around 65% (for example, 60% or more and 70% or less), the sensitivity of the electrode can be further increased, and the accuracy of electrochemical measurement can be further increased. Note that in FIG. 9, the scale of the vertical axis of the CV graph is different from those of the CV graphs shown in FIGS.

From FIG. 12 it can be seen that if the coverage is less than 15% (eg 1.2%), no oxidation current peak can be observed in the cyclic voltammogram and the electrode cannot be used as a working electrode in an electrochemical sensor. That is, it was found that when the coverage is 15% or more, an oxidation current peak can be observed in the cyclic voltammogram, and the electrode can be suitably used as a working electrode of an electrochemical sensor.

Also, the processing yield of electrodes obtained from samples 1 to 8 was evaluated. Specifically, first, using an automatic visual inspection device, the electrodes obtained from samples 1 to 8 were inspected, and the plane area was within ± 2% of the reference value and the angle formed by each side was 90 ° ± Electrodes within 2° were accepted. Then, the processing yield was calculated from the following (Equation 1). The processing yields (%) of samples 1 to 8 are shown in Table 1 below.
(Number 1)
Processing yield (%) = (number of acceptable electrodes/total number of electrodes obtained from each sample) x 100

From Table 1, it can be seen that the machining yield of the electrode can be improved by forming the diamond portion from granular crystals. Further, it can be seen that the lower the coverage, the more the processing yield improves, and the processing yield becomes 90% or more when the coverage is 75% or less.

<Preferred Embodiment of the Present Disclosure>
Preferred aspects of the present disclosure will be added below.

(Appendix 1)
According to one aspect of the present disclosure,
a support made of a material other than diamond;
a diamond portion supported on a support surface that is at least one of the surfaces of the support;
The diamond part is composed of a plurality of granular diamond crystals,
An electrode is provided wherein a portion of the support surface is exposed.

(Appendix 2)
The electrode according to Appendix 1, preferably comprising:
2. The electrode according to claim 1, wherein the ratio of the projected area of said plurality of granular diamond crystals onto said support surface to the plane area of said support surface is 15% or more and 90% or less, preferably 30% or more and 75% or less.

(Appendix 3)
The electrode according to Appendix 1 or 2, preferably
The surface area of the diamond portion is larger than the planar area of the support surface of the support.

(Appendix 4)
The electrode according to any one of Appendices 1 to 3, preferably
The average grain size of the plurality of granular diamond crystals is 60 nm or more and 150 nm or less, preferably 75 nm or more and 125 nm or less.

(Appendix 5)
The electrode according to any one of Appendices 1 to 4, preferably
The plurality of granular diamond crystals are randomly present on the support surface.

(Appendix 6)
The electrode according to any one of Appendices 1 to 5, preferably
An insulating film is formed on a region (exposed region) of the supporting surface that is not in contact with the plurality of granular diamond crystals. That is, the passivation of the regions of the support surface that are not in contact with the plurality of granular diamond crystals is achieved by forming an insulating film in the regions of the support surface that are not in contact with the plurality of granular diamond crystals. is done.

(Appendix 7)
The sensor according to appendix 6, preferably comprising:
The insulating film has a thickness of 1 nm or more,
The insulating film covers the entire area of the supporting surface that is not in contact with the plurality of granular diamond crystals.

(Appendix 8)
The electrode according to any one of Appendices 1 to 7, preferably
The support is formed using silicon alone or a silicon compound. Preferably, the support is made of a single crystal silicon substrate, a polycrystalline silicon substrate, or a silicon carbide substrate.

(Appendix 9)
The electrode according to any one of Appendices 1 to 8, preferably
The diamond portion contains boron at a concentration of 1×10 ¹⁹ cm ⁻³ or more and 1×10 ²² cm ⁻³ or less.

(Appendix 10)
The electrode according to any one of Appendices 1 to 9, preferably
It is used as a working electrode in electrochemical measurements. Preferably, it is a chip-like electrode having a rectangular outer shape in plan view.

(Appendix 11)
The electrode according to any one of Appendices 1 to 10, preferably
The diamond part does not have a fracture surface.

(Appendix 12)
The electrode according to any one of Appendices 1 to 11, preferably
The diamond portion has no residual stress.

(Appendix 13)
The electrode according to any one of Appendices 1 to 12, preferably
An image of the diamond portion projected onto the support surface is entirely within the support surface. That is, the diamond portion does not have an overhanging region from the support surface.

(Appendix 14)
According to another aspect of the present disclosure,
A diamond portion is formed by growing a plurality of granular diamond crystals on a supporting surface, which is at least one of the surfaces of a support made of a material other than diamond, such that a portion of the supporting surface is exposed. A method of manufacturing an electrode is provided that includes the step of providing.

(Appendix 15)
The method according to Appendix 14, preferably comprising:
In the step of providing the diamond part, the ratio of the projected area of the plurality of granular diamond crystals onto the support surface to the plane area of the support surface is 15% or more and 90% or less, preferably 30% or more and 75% or less. to grow said plurality of granular diamond crystals. Preferably, in the step of providing the diamond portion, the plurality of granular diamond crystals are grown such that the average grain size is 60 nm or more and 150 nm or less, preferably 75 nm or more and 125 nm or less.

(Appendix 16)
The method according to appendix 14 or 15, preferably
Before the step of providing the diamond portion, a step of performing a predetermined seeding treatment or scratching treatment on the support surface of the support is further performed,
In the step of providing the diamond portion, the plurality of granular diamond crystals are randomly grown on the support surface.

(Appendix 17)
The method according to any one of appendices 14 to 16, preferably
The method further comprises passivating regions of the support surface not contacted by the plurality of granular diamond crystals.

(Appendix 18)
The method according to Appendix 17, preferably comprising:
In the passivating step, the laminate having the support and the diamond portion is annealed in an oxygen-containing atmosphere or a nitrogen-containing atmosphere.

REFERENCE SIGNS LIST 10 electrode 11 diamond portion 11a granular diamond crystal 12 support 12s support surface

Claims (11)

a support made of a material other than diamond;
a diamond portion supported on a support surface that is at least one of the surfaces of the support;
The diamond part is composed of a plurality of granular diamond crystals,
An electrode, wherein a portion of the support surface is exposed. 2. The electrode according to claim 1, wherein the ratio of the projected area of said plurality of granular diamond crystals onto said support surface with respect to the plane area of said support surface is 15% or more and 90% or less. 3. The electrode according to claim 1, wherein the average grain size of said plurality of granular diamond crystals is 60 nm or more and 150 nm or less. The electrode according to any one of claims 1 to 3, wherein said plurality of granular diamond crystals are randomly present on said support surface. 5. The electrode according to any one of claims 1 to 4, wherein an insulating film is formed on a region of said support surface that is not in contact with said plurality of granular diamond crystals. 6. The electrode according to any one of claims 1 to 5, wherein the support is made of silicon alone or a silicon compound. The electrode according to any one of claims 1 to 6, wherein the diamond part contains boron at a concentration of ¹ x 1019 cm ^-3 or more and ¹ x 1022 cm ^-3 or less. The electrode according to any one of claims 1 to 7, which is used as a working electrode in electrochemical measurements. A diamond portion composed of a plurality of granular diamond crystals is grown on a support surface, which is at least one of the surfaces of a support made of a material other than diamond, such that a portion of the support surface is exposed. A method of manufacturing an electrode, comprising the step of: 10. The method of claim 9, further comprising the step of passivating regions of said support surface not contacted by said plurality of granular diamond crystals. 11. The method of manufacturing an electrode according to claim 10, wherein in the passivating step, the laminate having the support and the diamond part is annealed in an oxygen-containing atmosphere or a nitrogen-containing atmosphere.

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