Electrode chip and electronic devices

Abstract

To provide an electrode chip which prevents a liquid insulating resin from expanding up to an electrode film on the side face of a conductive substrate, and has high adhesion to the insulating resin, and an electronic apparatus having the electrode chip.SOLUTION: An electrode chip has a conductive substrate, and an electrode film which is provided on a crystal growth surface that is one main surface out of two main surfaces of the conductive substrate, and is composed of a polycrystal diamond, wherein two kinds of regions of a region composed of a smooth surface and a region composed of a non-smooth surface are formed on the side face of the conductive substrate, and the smooth surface is formed in a belt shape continuous in the circumferential direction of the conductive substrate.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to electrode tips and electronic devices. [Background technology]

[0002] An electrode chip having a conductive substrate and an electrode film formed on the conductive substrate and composed of polycrystalline diamond has a wide potential window and a small background current, and therefore can perform highly sensitive electrochemical detection of various substances such as uric acid, highly efficient electrochemical electrolysis processes such as water treatment and wastewater treatment, and highly efficient electrochemical ozone generation processes. Therefore, in recent years, it has been proposed to use the above-mentioned electrode chip as an electrochemical electrode, such as a working electrode of an electrochemical sensor, an electrolysis electrode used in wastewater treatment, or an electrode for ozone generation (see, for example, Patent Documents 1 to 3). Electronic devices such as electrochemical sensors using such electrode chips can be fabricated by electrically connecting the electrode chip to electrical wiring arranged on a support substrate via a conductive bonding material and sealing the junction between the electrode chip and the electrical wiring with an insulating resin. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2020-144116 [Patent Document 2] Japanese Patent Application Laid-Open No. 2004-35908 [Patent Document 3] Japanese Patent Application Publication No. 2019-23326 Summary of the Invention [Problem to be solved by the invention]

[0004] The above-mentioned sealing with insulating resin is performed by applying a liquid insulating resin to surround the electrode chip, and then thermally curing or ultraviolet curing the liquid insulating resin. However, when the liquid insulating resin is applied, the liquid insulating resin may spread along the side of the conductive substrate of the electrode chip to the electrode film, causing the liquid insulating resin to adhere to the electrode film. As a result, the sensitivity of electrochemical detection may decrease, and the efficiency of electrolysis and ozone generation processes may decrease. The present disclosure provides an electrode chip in which the liquid insulating resin is less likely to spread along the side of the conductive substrate to the electrode film and has high adhesion to the insulating resin, and an electronic device having this electrode chip. [Means for solving the problem]

[0005] According to one aspect of the present disclosure, a conductive substrate; an electrode film made of polycrystalline diamond provided on a crystal growth surface, which is one of the two main surfaces of the conductive substrate; and two types of regions, a region formed of a smooth surface and a region formed of a non-smooth surface, are formed on the side surface of the conductive substrate; An electrode tip is provided in which the smooth surface is formed in the shape of a belt that is continuous in the circumferential direction of the conductive substrate.

[0006] According to another aspect of the present disclosure, A support substrate; Electrical wiring arranged on the support substrate; an electrode tip connected to the electrical wiring via a conductive bonding material, the electrode tip having an electrode film made of a conductive substrate and a polycrystalline diamond film provided on a crystal growth surface, which is one of two main surfaces of the conductive substrate; an insulating resin that covers the bonding material and a portion of a side surface of the conductive substrate; and two types of regions, a region formed of a smooth surface and a region formed of a non-smooth surface, are formed on the side surface of the conductive substrate; the smooth surface is formed in a belt shape that is continuous in the circumferential direction of the conductive substrate, The electronic device is provided in which the entire upper surface of the electrode film and at least a part of the smooth surfaces of the side surfaces are exposed without being covered with the insulating resin. [Effects of the Invention]

[0007] According to the present disclosure, it is possible to provide an electrode chip in which the liquid insulating resin is less likely to spread down the side of the conductive substrate to the electrode film and which has high adhesion to the insulating resin, and an electronic device having this electrode chip. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic perspective view of an electrochemical sensor according to one embodiment of the present disclosure. [Figure 2] FIG. 2 is a cross-sectional view taken along the line AA of the electrochemical sensor shown in FIG. [Figure 3] FIG. 1 is a diagram showing an example of a schematic cross section of an electrode tip according to an embodiment of the present disclosure. [Figure 4] FIG. 10 is a diagram showing another example of a schematic cross section of an electrode tip according to an embodiment of the present disclosure. [Figure 5] FIG. 1 is a schematic diagram of a vapor phase growth apparatus used to grow diamond crystals. [Figure 6] 10 is a cross-sectional view showing a state in which a concave groove is formed on the rear surface of a laminated substrate having a conductive substrate and an electrode film. FIG. [Figure 7] 10(a) to 10(f) are diagrams each showing still another example of a schematic cross section of an electrode tip according to one embodiment of the present disclosure. [Figure 8] FIG. 2 shows microscope images of the side surfaces of the conductive substrates of Sample 1 and Sample 2, and the measurement results of the arithmetic mean height (Sa) of the side surfaces of the conductive substrates. [Figure 9] FIG. 10 is a diagram showing microscope images of the side surfaces of the conductive substrates of Samples 3 and 4 and the measurement results of the arithmetic mean height (Sa) of the side surfaces of the conductive substrates. DETAILED DESCRIPTION OF THE INVENTION

[0009] <One aspect of the present disclosure> An embodiment of the present disclosure will be described below with reference to Figures 1 and 2, taking as an example an electrochemical sensor as an electronic device that measures the concentration of a substance to be detected in a test liquid by a three-electrode method. In this embodiment, as an example, the test liquid is human urine, and the substance to be detected is uric acid.

[0010] (1) Configuration of electronic devices As shown in Figures 1 and 2, the electrochemical sensor 10 (hereinafter also referred to as "sensor 10") according to this embodiment is configured to include a support substrate 11, electrical wiring 12 to 14 arranged on the support substrate 11, and an electrode chip (chip-shaped electrode) 20 having an electrode film 21 made of polycrystalline diamond.

[0011] The support substrate 11 (hereinafter also referred to as "substrate 11") is a substrate that supports the electrode chip 20 and the like. The substrate 11 is configured as a sheet-like (plate-like) member. The substrate 11 can be formed of an insulating material, such as an insulating composite resin, ceramic, glass, plastic, a flammable material, a biodegradable material, a nonwoven fabric, or paper. The substrate 11 is preferably formed of, for example, glass epoxy resin or polyethylene terephthalate (PET). The substrate 11 may also be a semiconductor substrate or a metal substrate configured so that the surface on which the electrode chip 20 and the like are to be provided has insulating properties. The planar shape of the substrate 11 can be, for example, rectangular. The substrate 11 has predetermined physical strength and mechanical strength, for example, strength that prevents bending or breakage within a certain period of time after urine is attached to it.

[0012] On one of the two main surfaces of the substrate 11 (hereinafter also referred to as the "upper surface of the substrate 11"), three wirings (electrical wirings) 12, 13, and 14 are arranged at a distance from one end to the other end in the longitudinal direction of the substrate 11. Examples of materials for forming the wirings 12 to 14 include various noble metals such as copper (Cu), gold (Au), platinum (Pt), silver (Ag), and palladium (Pd), various metals such as aluminum (Al), iron (Fe), nickel (Ni), chromium (Cr), and titanium (Ti), alloys containing these noble metals or metals as main components, oxides of the above noble metals, metals, or alloys, and carbon. The wirings 12 to 14 may be formed using the same material or different materials. The wirings 12 to 14 can be formed by a subtractive method, a semi-additive method, or the like. The wirings 12 to 14 can also be formed by a printing method such as screen printing, gravure printing, offset printing, or inkjet printing, or by a vapor deposition method.

[0013] An electrode chip 20 serving as a working electrode is electrically connected to one end of the wiring 12 via a conductive bonding material 15 (see FIG. 2). The electrode chip 20 is configured to include an electrode film 21 and a conductive substrate 22, and is placed on the substrate 11 with the electrode film 21 facing upward (i.e., the conductive substrate 22 faces the support substrate 11), and is fixed to the substrate 11 via the bonding material 15. The bonding material 15 may be a conductive paste (conductive adhesive), a conductive tape, or the like. Details of the electrode chip 20 will be described later.

[0014] The joint between the electrode chip 20 and the wiring 12, i.e., the bonding material 15 and a portion of the wiring 12, is sealed with an insulating resin 16 (see FIG. 2). The insulating resin 16 is provided so as to cover the bonding material 15 and a portion of the side surface 23 of the conductive substrate 22. The insulating resin 16 can be made of a thermosetting resin or a UV-curable resin. Examples of the thermosetting resin or UV-curable resin that can be used include epoxy-based insulating resins and novolac-based insulating resins. The insulating resin 16 can be provided, for example, by applying a liquid insulating resin (hereinafter also referred to as "liquid resin") before hardening around the bonding material 15 and the electrode chip 20 and then hardening the liquid resin by heating or UV irradiation. The liquid resin is applied, for example, so as to cover the bonding material 15 without exposing it and to cover a portion of the side surface 23 of the conductive substrate 22 (the lower region of the side surface 23).

[0015] A reference electrode 17 is connected to one end of the wiring 13. The reference electrode 17 is an electrode that serves as a reference when determining the potential of the electrode tip 20 (working electrode). The reference electrode 17 can be an electrode formed of a metal such as Pt, Au, Cu, Pd, Ni, or Ag. In this case, the reference electrode 17 can be formed integrally with the wiring 13 by a known method such as electroless plating. The reference electrode 17 can also be an electrode (BDD electrode) formed of a diamond crystal doped with boron (B). In this case, the reference electrode 17 can be electrically connected to the wiring 13 via a conductive bonding material such as conductive paste. The bond between the reference electrode 17 and the wiring 13, i.e., the bonding material and a portion of the wiring 13, are sealed with an insulating resin such as a thermosetting resin or an ultraviolet-curing resin. The reference electrode 17 can also be installed separately from the sensor 10. For example, a silver / silver chloride (Ag / AgCl) electrode can be used. The reference electrode 17 may also be a standard hydrogen electrode, a reversible hydrogen electrode, a palladium-hydrogen electrode, a saturated calomel electrode, a carbon electrode, or the like.

[0016] A counter electrode 18 is connected to one end of the wiring 14. The counter electrode 18 is provided so as to surround the electrode tip 20 and the reference electrode 17. The counter electrode 18 may be an electrode made of a metal such as Pt, Au, Cu, Pd, Ni, or Ag, or a carbon electrode. The counter electrode 18 is formed integrally with the wiring 14 by a subtractive method, a semi-additive method, or the like. The counter electrode 18 may also be formed separately from the wiring 14 and connected to the wiring 14 via a conductive bonding material such as a conductive paste.

[0017] The wires 12 to 14 are preferably covered with a waterproof member 19 made of insulating resin or the like so that urine does not come into contact with the wires 12 to 14 when urine is supplied to the sensor 10.

[0018] (2) Electrode chip configuration The configuration of the electrode chip 20 of the sensor 10 will be described mainly with reference to FIG.

[0019] 3, the electrode chip 20 according to this embodiment is configured to include an electrode film 21 and a conductive substrate 22 (also referred to as "substrate 22"). The electrode chip 20 is a vertical electrode that extracts, from the substrate 22 side, a current resulting from an electrochemical reaction generated on the surface of the electrode film 21. Such an electrode chip 20 can be suitably used as the working electrode of the sensor 10 described above.

[0020] The outer shape (planar shape) of the electrode tip 20 is rectangular, for example, square, when viewed from above in a direction perpendicular to the main surface of the substrate 22. The planar area of ​​the electrode tip 20 is, for example, 1 mm 2 More than 100mm 2 The planar area of ​​the electrode tip 20 is the area of ​​the electrode tip 20 when viewed from above in a direction perpendicular to the main surface of the substrate 22. 2If the above conditions are met, the electrode tip 20 can be obtained easily and stably with high accuracy by a technique using cleavage or splitting, which will be described later. It is also possible to prevent the electrode tip 20 from being deteriorated in handleability and mounting stability. 2 By keeping the thickness below 100 nm, it is possible to prevent the sensor 10 having the electrode tip 20 from becoming large, that is, it is possible to obtain a small sensor 10.

[0021] The electrode film 21 is provided on one of the two main surfaces of the substrate 22. In this specification, the main surface of the substrate 22 on which the electrode film 21 is provided is also referred to as the "crystal growth surface of the substrate 22." The electrode film 21 is provided over the entire crystal growth surface of the substrate 22. The electrode film 21 causes a predetermined electrochemical reaction (for example, an electrochemical reaction of uric acid in urine) on its surface (exposed surface). That is, when urine is supplied to the sensor 10, which includes an electrode group including the electrode chip 20, the reference electrode 17, and the counter electrode 18, and a predetermined voltage is applied to the electrode group while the urine is in contact with the electrode group, an oxidation-reduction reaction of uric acid occurs on the surface of the electrode film 21.

[0022] The electrode film 21 is made of polycrystalline diamond. Specifically, the electrode film 21 is a polycrystalline film (polycrystalline diamond film) made of diamond crystals containing boron (B) as a dopant, that is, diamond crystals having p-type conductivity. A diamond crystal is a crystal in which carbon (C) atoms are arranged in a pattern called a diamond crystal structure. The electrode film 21 may also be a diamond-like carbon (DLC) film. The B concentration in the electrode film 21 can be measured by secondary ion mass spectrometry (SIMS), and is, for example, 5×10 19 cm -3 5x10 or more 21 cm -3 The following can be mentioned: SIMS is a technique for measuring the concentration of a predetermined substance by detecting ions (secondary ions) generated when a beam of ions (primary ions) is irradiated onto the surface of the electrode film 21 using a mass spectrometer.

[0023] The electrode film 21 can be grown (deposited, synthesized) by a chemical vapor deposition (CVD) method, a physical vapor deposition (PVD) method, or the like. Examples of the CVD method include a hot filament CVD method using a tungsten filament and a plasma CVD method, and examples of the PVD method include an ion beam method and an ionization deposition method. The thickness of the electrode film 21 can be, for example, 0.5 μm to 10 μm, and preferably 2 μm to 4 μm.

[0024] A flat substrate made of a low-resistance material is used as the conductive substrate 22. The substrate 22 may be a substrate made mainly of silicon (Si) and containing a predetermined concentration of a p-type dopant such as boron (B), for example, a p-type single-crystal Si substrate. A p-type polycrystalline Si substrate may also be used as the substrate 22. The B concentration in the substrate 22 may be, for example, 5×10 18 cm -3 Over 1.5 x 10 20 cm -3 Less than or equal to 5 x 10 18 cm -3 Over 1.2 x 10 20 cm -3 By setting the B concentration in the substrate 22 within the above range, it is possible to reduce the resistivity of the substrate 22 while avoiding a decrease in the manufacturing yield and deterioration in the performance of the substrate 22.

[0025] The thickness of the substrate 22 can be, for example, 350 μm or more. This makes it possible to use commercially available single-crystal Si substrates with a diameter of 6 inches or 8 inches as the substrate 22 without adjusting the thickness by back-rapping. As a result, it is possible to increase the productivity of the electrode tip 20 and reduce manufacturing costs. There is no particular upper limit to the thickness of the substrate 22, but the thickness of a Si substrate currently commonly available on the market is approximately 775 μm for a single-crystal Si substrate with a diameter of 12 inches. Therefore, the upper limit of the thickness of the substrate 22 using current technology can be set to, for example, approximately 775 μm.

[0026] Substrates other than a substrate primarily composed of Si (Si substrate) can also be used as the substrate 22. For example, substrates composed of a Si compound such as a silicon carbide substrate (SiC substrate), a niobium (Nb) substrate, or a metal substrate primarily composed of molybdenum (Mo), titanium (Ti), or the like can also be used as the substrate 22.

[0027] The side surface 23 of the substrate 22 is formed with (only) two types of regions: a region made up of a smooth surface 24 (a region formed smoothly, hereinafter also referred to as a "smooth region"), and a region made up of a non-smooth surface 25 (a region formed smoothly, hereinafter also referred to as a "non-smooth region"). In other words, the side surface 23 is made up of (only) the smooth surface 24 and the non-smooth surface 25.

[0028] The smooth surface 24 has lower wettability with the liquid resin than the non-smooth surface 25, and the liquid resin does not easily spread (rise) on the smooth surface 24. On the other hand, the non-smooth surface 25 has higher wettability with the liquid resin than the smooth surface 24, and the liquid resin easily spreads on the non-smooth surface 25.

[0029] By forming the smooth surface 24 (smooth region) on the side surface 23, when the joint between the electrode chip 20 and the wiring 12 is sealed with insulating resin 16 during the manufacturing process of the sensor 10, the liquid resin applied to part of the side surface 23 of the substrate 22 is less likely to spread along the side surface 23 toward the electrode film 21, and as a result, the liquid resin is less likely to reach the electrode film 21. This makes it possible to prevent the liquid resin from adhering to the electrode film 21, and as a result, a decrease in the sensor sensitivity of the sensor 10 is less likely to occur.

[0030] Furthermore, the smooth surface 24 is formed in a belt-like shape that is continuous in the circumferential direction of the substrate 22. As a result, during resin sealing in the manufacturing process of the sensor 10, the liquid resin applied to (a portion of) the side surface 23 is less likely to spread along the side surface 23 to the electrode film 21, making it less likely for the liquid resin to reach the electrode film 21 and adhere to the electrode film 21. Therefore, the liquid resin hardens without getting on the electrode film 21 or covering at least a portion of the smooth surface 24. That is, the liquid resin can be hardened without adhering anywhere on the upper surface of the electrode film 21 or at least in the upper region (the region on the electrode film 21 side) of the smooth surface 24. As a result, in the sensor 10, the entire upper surface of the electrode film 21 and at least a portion of the smooth surface 24 are exposed without being covered by the insulating resin 16. By exposing the entire upper surface of the electrode film 21, i.e., by providing the insulating resin 16 without getting on the electrode film 21, a decrease in the sensitivity of the sensor 10 can be avoided. The "upper surface of the electrode film 21" refers to one of the two main surfaces of the electrode film 21 opposite to the surface facing the substrate 22.

[0031] If the smooth surface 24 is not formed in the shape of a continuous belt in the circumferential direction of the substrate 22, that is, if the smooth surface 24 is formed discontinuously in the circumferential direction of the substrate 22, the liquid resin may reach the electrode film 21. In other words, the liquid resin may spread along the non-smooth surfaces 25 present between the smooth surfaces 24 in the circumferential direction of the substrate 22 toward the electrode film 21 and reach the electrode film 21.

[0032] The smooth surface 24 can be a surface having an arithmetic mean height (Sa) of, for example, 1 μm or less, preferably 0.5 μm or less. The smooth surface 24 can be composed of, for example, a cleavage plane, a split plane, or a mixture of these. The term "cleavage plane" as used herein refers to a surface formed when a material such as a crystal is subjected to an external force and splits parallel to a certain plane other than a cleavage plane.

[0033] When Sa of the smooth surface 24 is, for example, 1 μm or less, the wettability can be sufficiently low. This reliably prevents the liquid resin from spreading along the side surface 23 to the electrode film 21, making it more difficult for the liquid resin to reach the electrode film 21. When Sa of the smooth surface 24 is 0.5 μm or less, the wettability can be even more sufficiently low. This reliably prevents the liquid resin from spreading along the side surface 23 to the electrode film 21, making it even more difficult for the liquid resin to reach the electrode film 21. If Sa of the smooth surface 24 exceeds 1 μm, the wettability cannot be sufficiently low, and the liquid resin may spread along the side surface 23 to the electrode film 21.

[0034] There is no particular limitation on the lower limit of Sa of the smooth surface 24. However, in measurements using a laser microscope, which is a common method for evaluating Sa, Sa is rarely (if ever) less than 0.1 μm. Therefore, the lower limit of Sa of the smooth surface 24 can be set to, for example, 0.1 μm.

[0035] The arithmetic mean height (Sa) is a parameter that expands the arithmetic mean roughness (Ra) of a line into three dimensions (surface), i.e., a parameter for evaluating surface roughness, and is a numerical value that represents the average of the absolute values ​​of the differences in height from the average surface of each measurement point in a reference area (evaluation area). In other words, the "arithmetic mean height (Sa) of the smooth surface 24" is the average value of the height or depth of each irregularity on the smooth surface 24 relative to the surface obtained by averaging the height of the smooth surface 24.

[0036] The arithmetic mean height (Sa) can be calculated by measuring the smooth surface 24 using a laser microscope and using the following formula 1. In the following formula 1, A is the area of ​​the reference region (evaluation area), and z(x, y) is the difference in height from the average surface at each measurement point.

[0037]

number

[0038] Moreover, examples of the evaluation conditions for Sa of the smooth surface 24 include the following conditions.

[0039] <Evaluation conditions for Sa of smooth surfaces> Laser microscope: Keyence laser microscope VK-X1100 Magnification: Objective lens x20 Evaluation position: A position within the smooth region, and a position that does not straddle the boundary between the smooth region and the non-smooth region Evaluation region (evaluation area): A quadrilateral region with one side of 5 μm to 30 μm, preferably a quadrilateral region with one side of 10 μm to 20 μm

[0040] On the other hand, as described above, the non-smooth surface 25 has a higher wettability with the liquid resin than the smooth surface 24. The formation of the non-smooth surface 25 (non-smooth region) on the side surface 23 allows the liquid resin to spread over the entire surface of the non-smooth surface 25 during resin sealing in the manufacturing process of the sensor 10. This can be achieved by capillary action caused by the irregularities of the non-smooth surface 25, or by the liquid resin soaking into nanoparticles that are generated and adhere to the non-smooth surface 25 during the manufacturing process of the electrode chip 20 (e.g., during step A (laser processing, machining, etc.), or during the roughening process, described below). As a result, the entire surface of the non-smooth surface 25 can be sufficiently wetted with the liquid resin. This increases the contact area between the non-smooth surface 25 and the liquid resin, and can sufficiently enhance adhesion between the cured resin (i.e., the insulating resin 16) and the non-smooth surface 25 (side surface 23) due to the anchor effect. As a result, the insulating resin 16 can tightly seal from the non-smooth surface 25 (the entire non-smooth surface 25) to the support substrate 11. This provides an insulating effect by the insulating resin 16, and for example, can suppress the occurrence of leakage (leakage current) via the bonding material 15 or the electrical wiring 12 when the sensor 10 is driven. Furthermore, by improving the adhesion, the fixing strength of the electrode chip 20 in the sensor 10 can also be increased. As a result, it is possible to prevent the electrode chip 20 from peeling off from the substrate 11. In this specification, "adhesion between the insulating resin 16 and the non-smooth surface 25 (side surface 23)" will also be referred to simply as "adhesion," and "fixing strength of the electrode chip 20 in the sensor 10" will also be referred to simply as "chip fixing strength."

[0041] The non-smooth surface 25 can be a surface having an arithmetic mean height (Sa) of, for example, more than 1 μm, preferably 2 μm or more. The non-smooth surface 25 can be formed, for example, by a melted surface (laser-processed surface) or a machined surface (machined surface). The term "melted surface" as used herein refers to a surface with relatively high surface roughness, including an amorphous surface formed by, for example, a crystal being melted by laser irradiation and then rapidly solidifying. The term "machined surface" as used herein refers to a surface with relatively high surface roughness, including processing damage caused by machining.

[0042] For example, if Sa of the non-smooth surface 25 is greater than 1 μm, the wettability of the non-smooth surface 25 can be sufficiently increased, and the entire non-smooth surface 25 can be sufficiently wetted with liquid resin during resin sealing in the manufacturing process of the sensor 10. This reliably improves the adhesion. As a result, the entire non-smooth surface 25 can be reliably sealed with the insulating resin 16, and the chip fixing strength can be reliably increased. If Sa of the non-smooth surface 25 is 2 μm or more, the entire non-smooth surface 25 can be even more reliably sealed with the insulating resin 16, and the chip fixing strength can be even more reliably increased. If Sa of the non-smooth surface 25 is 1 μm or less, the anchor effect cannot be sufficiently obtained during resin sealing in the manufacturing process of the sensor 10, and the adhesion may be reduced.

[0043] The upper limit of Sa of the non-smooth surface 25 is not particularly limited. However, in the manufacturing method of the electrode tip 20 described below, it is very difficult to form a non-smooth surface 25 on the side surface 23 with Sa exceeding 20 μm. Furthermore, if Sa exceeds 20 μm, the obtained electrode tip 20 may be determined to be a defective product in a quality inspection. For example, an error may occur in the evaluation of the size of the electrode tip 20 (the planar area of ​​the electrode tip 20 when viewed from the electrode film 21 side), and the electrode tip 20 may be determined to be of inappropriate size. Furthermore, for example, the sensor sensitivity value calculated by converting the electrode tip 20 into a unit area may fall outside the specified range. For this reason, the upper limit of Sa of the non-smooth surface 25 may be set to, for example, 20 μm.

[0044] The "arithmetic mean height (Sa) of non-smooth surface 25" is the average value of the height or depth of each irregularity on non-smooth surface 25 relative to the average height of non-smooth surface 25. Sa of non-smooth surface 25 can be calculated by measuring non-smooth surface 25 using, for example, a laser microscope and using the above-mentioned (Equation 1). Examples of conditions for evaluating Sa of non-smooth surface 25 include the following conditions.

[0045] <Evaluation conditions for Sa of non-smooth surfaces> Laser microscope: Keyence laser microscope VK-X1100 Magnification: Objective lens x20 Evaluation position: A position within a non-smooth region that does not straddle the boundary between a smooth region and a non-smooth region Evaluation region (evaluation area): A quadrilateral region with one side of 5 μm to 30 μm, preferably a quadrilateral region with one side of 10 μm to 20 μm

[0046] As described above, by configuring the side surface 23 with a smooth surface 24 and a non-smooth surface 25, and by forming the smooth surface 24 in a belt shape, it is possible to simultaneously obtain in a balanced manner the effect of preventing the liquid resin from spreading along the side surface 23 to the electrode film 21 (hereinafter also referred to as the "resin spreading prevention effect"), the effect of sealing the non-smooth surface 25 with insulating resin 16 (hereinafter also referred to as the "resin sealing effect"), and the effect of increasing the chip fixing strength (hereinafter also referred to as the "chip fixing strength improvement effect").

[0047] As described above, the smooth surface 24 has lower wettability with the liquid resin than the non-smooth surface 25. Therefore, if the side surface 23 is composed only of the smooth surface 24, the adhesion will be reduced. In other words, in this case, although the resin spreading prevention effect is sufficiently obtained, the resin sealing effect and the effect of improving the chip fixing strength are difficult to obtain. On the other hand, as described above, the non-smooth surface 25 has higher wettability with the liquid resin than the smooth surface 24, and the liquid resin easily spreads on the non-smooth surface 25. Therefore, if the side surface 23 is composed only of the non-smooth surface 25, the liquid resin will easily spread over the entire side surface 23 due to capillary action caused by the unevenness of the non-smooth surface 25 or the liquid resin seeping into nanoparticles that are generated during the implementation of step A described below and adhere to the non-smooth surface 25. In other words, in this case, the liquid resin will easily spread along the side surface 23 (non-smooth surface 25) to the electrode film 21 and easily reach the electrode film 21. In particular, when a thermosetting resin is used as the liquid resin, the liquid resin easily spreads down the side surface 23 (uneven surface 25) to the electrode film 21 due to the thixotropy of the thermosetting resin, which causes the viscosity of the thermosetting resin to temporarily decrease during the curing process. As described above, when the side surface 23 is composed only of the uneven surface 25, the resin sealing effect and the effect of improving the chip fixing strength are sufficiently obtained, but the effect of preventing the resin from spreading is difficult to obtain. As described above, when the side surface 23 is composed only of the smooth surface 24 or the uneven surface 25, it is difficult to simultaneously obtain a balanced effect of preventing the resin from spreading, the resin sealing effect, and the effect of improving the chip fixing strength.

[0048] Like the smooth surface 24, the non-smooth surface 25 is preferably formed in the shape of a belt that continues in the circumferential direction of the substrate 22. This makes it easier to obtain the effect of resin sealing and the effect of improving the chip fixing strength.

[0049] Furthermore, it is preferable that the non-smooth surface 25 is formed at least in a region (lower region) of the side surface 23 that is lower than the smooth surface 24. In this specification, the "upper side" refers to the crystal growth surface side (electrode film 21 side) of the substrate 22 in the thickness direction of the substrate 22, as shown by the arrow in FIG. 3, and the "lower side" refers to the main surface side different (opposite) from the crystal growth surface in the thickness direction of the substrate 22, as shown by the arrow in FIG. 3. By forming the non-smooth surface 25 in such a region, the adhesion can be improved in the lower region of the side surface 23 (the region of the side surface 23 closer to the substrate 11 in the sensor 10). As a result, the resin sealing effect and the effect of improving the chip fixing strength can be easily obtained.

[0050] It is more preferable that the non-smooth surface 25 is formed in a belt shape and is formed in a region of the side surface 23 below the smooth surface 24. This allows the lower region of the side surface 23 to be uniformly covered with the insulating resin 16 without being exposed, while also improving the adhesion in the lower region of the side surface 23. As a result, the resin sealing effect and the effect of improving the chip fixing strength can be reliably obtained.

[0051] Furthermore, it is preferable that the smooth surface 24 is formed in the upper region of the side surface 23, and the non-smooth surface 25 is formed in the lower region of the side surface 23. This makes it possible to reliably obtain a balanced effect of preventing resin spreading, a resin sealing effect, and an effect of improving chip fixing strength all at the same time.

[0052] Furthermore, it is preferable that at least a portion of the upper edge (upper edge) 24t of the smooth surface 24 is in contact with the upper edge 23t of the side surface 23, and it is preferable that at least a portion of the lower edge (lower edge) 25b of the non-smooth surface 25 is in contact with the lower edge 23b of the side surface 23.

[0053] The closer at least a portion of the upper edge 24t of the smooth surface 24 to the upper edge 23t of the side surface 23, the more reliably the resin spread prevention effect can be obtained by forming the smooth surface 24 in the upper region of the side surface 23. It is also more preferable that the entire upper edge 24t of the smooth surface 24 be in contact with the entire upper edge 23t of the side surface 23, thereby more reliably obtaining the resin spread prevention effect. Figure 3 shows an example in which the entire upper edge 24t of the smooth surface 24 is in contact with the entire upper edge 23t of the side surface 23, i.e., an example in which the upper edge 24t of the smooth surface 24 and the upper edge 23t of the side surface 23 are aligned.

[0054] Furthermore, since the non-smooth surface 25 is formed in a lower region of the side surface 23, the closer at least a portion of the lower edge 25b of the non-smooth surface 25 is to the lower edge 23b of the side surface 23, the more the adhesion can be improved on the side of the side surface 23 closer to the substrate 11. This more reliably achieves the resin sealing effect and the chip fixing strength improvement effect. It is more preferable that the entire lower edge 25b of the non-smooth surface 25 is in contact with the lower edge 23b of the side surface 23, which more reliably achieves the resin sealing effect and the chip fixing strength improvement effect. Note that FIG. 3 shows an example in which the entire lower edge 25b of the non-smooth surface 25 is in contact with the lower edge 23b of the side surface 23, i.e., an example in which the lower edge 25b of the non-smooth surface 25 and the lower edge 23b of the side surface 23 are aligned.

[0055] The height 24h of the smooth surface 24 can be, for example, 10 μm or more. Here, the "height 24h of the smooth surface 24" refers to the distance between the lower edge 24b and the upper edge 24t of the smooth surface 24 in the direction perpendicular to the crystal growth surface (vertical direction). If the height 24h of the smooth surface 24 is, for example, 10 μm or more at its shortest point, the resin spreading prevention effect can be reliably obtained. If the height 24h of the smooth surface 24 is less than 10 μm, the resin spreading prevention effect cannot be sufficiently obtained, and the liquid resin may adhere to the electrode film 21.

[0056] The height 24h of the smooth surface 24 can be, for example, 250 μm or less, or can be, for example, 80% or less of the thickness of the substrate 22. This allows the substrate 22 to be divided accurately, stably, and easily by a cleavage or splitting technique described below in the process of manufacturing the electrode tip 20, thereby preventing a decrease in the manufacturing yield of the electrode tip 20. If the height 24h of the smooth surface 24 exceeds 250 μm or exceeds 80% of the thickness of the substrate 22, it becomes difficult to divide the substrate 22 by a cleavage or splitting technique, and the manufacturing yield of the electrode tip 20 may decrease.

[0057] Furthermore, it is desirable that the height 24h of the smooth surface 24 be uniform across the entire belt-shaped smooth surface 24. For example, it is desirable that the difference between the maximum and minimum values ​​of the height 24h of the smooth surface 24 in one electrode tip 20 be 50 μm or less. If there is a large variation in the height 24h of the smooth surface 24 (if the difference between the maximum and minimum values ​​of the height 24h is large), the variation in the height 25h of the non-smooth surface 25 will also be large. In particular, if there is a large variation in the position of the lower edge 24b of the smooth surface 24, the variation in the height 25h of the non-smooth surface 25 will be significant. If the variation in the height 25h is large, the insulating resin 16 will be unevenly attached around the electrode tip 20, resulting in variations in the resin sealing effect and the effect of improving the chip fixation strength.

[0058] The height 25h of the non-smooth surface 25 can be, for example, 50 μm or more. The "height 25h of the non-smooth surface 25" here refers to the distance between the lower edge 25b and the upper edge 25t of the non-smooth surface 25 in a direction perpendicular to the crystal growth surface. Specifically, the distance between the lower edge 25b of the non-smooth surface 25 at the point where it contacts the lower edge 23b of the side surface 23 and the upper edge 25t of the non-smooth surface 25 in a direction perpendicular to the crystal growth surface. By ensuring that the height 25h of the non-smooth surface 25 is, for example, 50 μm or more at its shortest point, a highly wettable region, i.e., a region with high adhesion, can be sufficiently secured. This ensures the resin encapsulation effect and the chip fixation strength improvement effect. If the height 25h of the non-smooth surface 25 is less than 50 μm, the region with high adhesion cannot be sufficiently secured, and the resin encapsulation effect and the chip fixation strength improvement effect may not be sufficiently secured.

[0059] The height 24h of the smooth surface 24 and the height 25h of the non-smooth surface 25 can be adjusted appropriately within the above-mentioned range. For example, as shown in FIG. 3, by making the height 25h of the non-smooth surface 25 larger than the height 24h of the smooth surface 24 (height 25h > height 24h), a region with high wettability, i.e., a region with high adhesion, can be sufficiently secured, thereby reliably achieving the resin encapsulation effect and the chip fixation strength improvement. As the height 25h of the non-smooth surface 25 increases, the resin encapsulation effect and the chip fixation strength improvement are more likely to be achieved. Furthermore, as shown in FIG. 4, by making the height 24h of the smooth surface 24 larger than the height 25h of the non-smooth surface 25 (height 24h > height 25h), the spread of the liquid resin onto the electrode film 21 can be reliably prevented. As shown in FIG. 3, by making the height 24h of the smooth surface 24 larger than the height 25h of the non-smooth surface 25, the resin spread prevention effect can be more reliably achieved.

[0060] Furthermore, it is desirable that the non-smooth surface 25 be formed in a belt shape around the entire circumference of the side surface 23 of the electrode tip 20, and that the height 25h thereof be uniform across the entire non-smooth surface 25. For example, it is desirable that the difference between the maximum and minimum values ​​of the height 25h of the non-smooth surface 25 in one electrode tip 20 be 50 μm or less. If the height 25h of the non-smooth surface 25 varies greatly, the insulating resin 16 will be applied unevenly around the electrode tip 20, resulting in variations in the resin sealing effect and the effect of improving the chip fixing strength.

[0061] (3) Manufacturing method of electrode chip and electrochemical sensor Next, a method for manufacturing the electrode tip 20 and the sensor 10 will be described.

[0062] [Fabrication of electrode chips] First, the electrode tip 20 is fabricated.

[0063] (Preparing a conductive substrate) As the conductive substrate 22, for example, a flat Si substrate having a circular outer shape in a planar view is prepared. Then, of the two main surfaces of the substrate 22, the surface on which diamond crystals will grow (deposit) (i.e., the crystal growth surface of the substrate 22) is subjected to a scratching treatment in the atmosphere to increase the diamond nucleation density. The scratching treatment is a process of inflicting processing damage on the crystal growth surface, for example, a process of scratching the crystal growth surface using diamond abrasive grains (diamond powder) of about several micrometers. Instead of or in addition to the scratching treatment, a seeding treatment may be performed. The seeding treatment is a process of attaching diamond particles (seeds) to the crystal growth surface by, for example, applying a solution (dispersion) in which diamond particles (preferably diamond nanoparticles) of about several nanometers to several tens of micrometers are dispersed to the crystal growth surface or immersing the substrate 22 in the dispersion.

[0064] (Diamond crystal growth) After the scratching or seeding process is completed, polycrystalline diamond is grown (deposited) on the crystal growth surface of the substrate 22 by, for example, a hot filament CVD method using a tungsten filament to form the electrode film 21.

[0065] Diamond crystals can be grown using, for example, a hot filament CVD apparatus 300 as shown in Figure 5. The hot filament CVD apparatus 300 has a growth chamber 301 therein and is equipped with an airtight container 303 made of a heat-resistant material such as quartz. A susceptor 308 for holding a substrate 22 is provided within the growth chamber 301.

[0066] Gas supply pipes 332a to 332d are connected to the sidewall of the airtight container 303. Flow rate controllers 341a to 341d and valves 343a to 343d are respectively provided on the gas supply pipes 332a to 332d, in that order from the upstream side of the gas flow. Nozzles 349a to 349d are respectively connected to the downstream ends of the gas supply pipes 332a to 332d, for supplying the gases supplied from the gas supply pipes 332a to 332d into the growth chamber 301. Nitrogen (N2) gas is supplied from the gas supply pipe 332a into the growth chamber 301 via nozzle 349a. Hydrogen (H2) gas is supplied from the gas supply pipe 332b into the growth chamber 301 via nozzle 349b. B-containing gas is supplied from the gas supply pipe 332c into the growth chamber 301 via nozzle 349c. Examples of the B-containing gas include trimethylboron (B(CH3)3, abbreviated as TMB) gas and diborane (B2H6) gas. A C-containing gas is supplied from the gas supply pipe 332d through a nozzle 349d into the growth chamber 301. Examples of the C-containing gas include methane (CH4) gas and ethane (C2H6) gas. An exhaust pipe 330 for evacuating the growth chamber 301 is provided on another side wall of the airtight container 303. 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. Also provided inside the airtight container 303 are a tungsten filament 310 and a pair of electrodes (e.g., molybdenum (Mo) electrodes) 311a and 311b that hold the tungsten filament 310 and are connected to a power source (not shown). Each component included in the hot filament CVD apparatus 300 is connected to a controller 380 configured as a computer, and the processing procedures and processing conditions described below are controlled by a program executed on the controller 380.

[0067] First, the substrate 22 is loaded (carried) into the growth chamber 301 (airtight container 303) configured to be able to supply various gases including a B-containing gas and a C-containing gas, and is held on the susceptor 308. Next, a current is passed between electrodes 311a and 311b to start heating the tungsten filament 310. As the tungsten filament 310 is heated, the substrate 22 held on the susceptor 308 is also heated. Furthermore, while the growth chamber 301 is being evacuated, the supply of H gas, a B-containing gas (e.g., TMB gas), and a C-containing gas (e.g., CH gas) into the growth chamber 301 is started. At this time, N gas may be supplied into the growth chamber 301 as needed. The heating of the tungsten filament 310, i.e., the heating of the substrate 22, the evacuation of the growth chamber 301, and the supply of various gases into the growth chamber 301, continue at least until the growth of the diamond crystal is completed.

[0068] When the temperature of substrate 22 reaches a predetermined temperature (diamond crystal growth temperature), the B-containing gas and C-containing gas decompose (thermally decompose), generating predetermined active species. By supplying the predetermined active species onto the crystal growth surface of substrate 22, a diamond crystal (polycrystalline diamond) containing B element grows on substrate 22. When the temperature of substrate 22 reaches the diamond crystal growth temperature, the temperature of tungsten filament 310 is controlled so that the temperature of substrate 22 is maintained at the diamond crystal growth temperature.

[0069] The conditions for growing diamond crystals are exemplified as follows: Pressure in the growth chamber: 5 Torr or more and 50 Torr or less (665 Pa or more and 6650 Pa or less), preferably 10 Torr or more and 35 Torr or less (1330 Pa or more and 4655 Pa or less) Ratio of the amount of B-containing gas supplied to the amount of C-containing gas supplied (B-containing gas / C-containing gas): 0.003% or more and 0.8% or less Growth temperature: 600°C or higher and 1000°C or lower, preferably 650°C or higher and 800°C or lower Filament temperature: 1800°C or higher and 2500°C or lower, preferably 2000°C or higher and 2200°C or lower Growth time: 200 minutes or more and 500 minutes or less, preferably 300 minutes or more and 500 minutes or less Ratio of C-containing gas supply to H2 gas supply (C-containing gas / H2 gas): 2% to 5%

[0070] By growing diamond crystals under the above conditions, it is possible to obtain a laminated substrate 20a in which an electrode film 21 made of polycrystalline diamond is laminated on a substrate 22.

[0071] After the growth of the diamond crystal is completed, the supply of each gas into the growth chamber 301 and the heating of the tungsten filament 310 are stopped. Then, when the temperature inside the growth chamber 301 has decreased to a predetermined temperature, the laminated substrate 20a is carried out from the growth chamber 301 to the outside of the airtight container 303.

[0072] (Dividing the laminated board) Next, the laminated substrate 20a is divided into predetermined shapes (for example, chip shapes).

[0073] In this embodiment, the dividing sequence of the laminated substrate 20a is as follows: A process of forming a concave groove 31 on the back surface of the laminated substrate 20a (step A); A process (step B) of bonding plate-shaped members to the front and back surfaces of the laminated substrate 20a using an adhesive or an adhesive material; a process (step C) in which, with plate-like members attached to the front and back surfaces of the laminated substrate 20a, stress is applied to the substrate 22 from the substrate 22 side of the laminated substrate 20a to cleave or split the substrate 22 and divide the substrate 22; A process (step D) of applying stress to the electrode film 21 from the electrode film 21 side in a state where the plate-shaped members are attached to the front and back surfaces of the laminated substrate 20a to divide the electrode film 21; The following steps are taken in this order:

[0074] <Step A: Forming a concave groove> Specifically, as shown in FIG. 6, first, a concave groove 31 (e.g., a laser-processed groove, a scribed groove, or a diced groove) is formed on the back surface of the laminated substrate 20a, i.e., the back surface of the substrate 22. The "back surface of the substrate 22" refers to one of the two main surfaces of the substrate 22 that is opposite the crystal growth surface. The groove 31 can be formed using known techniques such as laser processing methods such as laser scribing and laser dicing, mechanical processing methods, and etching. For example, by continuously irradiating and sweeping a laser beam onto the back surface of the laminated substrate 20a to form the groove 31, a belt-like non-smooth surface 25 that is continuous in the circumferential direction of the substrate 22 can be formed on the side surface 23 of the substrate 22 in the resulting electrode chip 20.

[0075] The following conditions are examples of the laser beam irradiation conditions when forming the grooves 31 by laser processing.

[0076] <Laser light irradiation conditions> Laser light: 532 nm, 5 W, 10 kHz, spot diameter 2 μm Scanning speed: 5 mm / sec or more and 20 mm / sec or less, preferably 7 mm / sec or more and 15 mm / sec or less Number of scans: 3 to 10

[0077] When forming the grooves 31, the depth of the grooves 31 is adjusted so that they do not penetrate the substrate 22 in the thickness direction, i.e., so that they do not reach the electrode film 21. The depth of the grooves 31 can be adjusted, for example, by adjusting the number of laser beam scans (number of laser beam irradiations). By adjusting the depth of the grooves 31, the ratio of the height 24h of the smooth surface 24 to the height 25h of the non-smooth surface 25 in the resulting electrode tip 20 can be adjusted. When forming the grooves 31, the depth of the grooves 31 can be adjusted so that the thickness of the thinnest part of the substrate 22 is reduced (the grooves 31 are deepened), thereby increasing the height 25h of the non-smooth surface 25. Furthermore, when forming the grooves 31, the depth of the grooves 31 can be adjusted so that the thickness of the thinnest part of the substrate 22 is increased (the grooves 31 are shallower), thereby increasing the height 24h of the smooth surface 24. Note that, as used herein, the term "thickness of the thinnest part of the substrate 22" refers to the thickness of the thinnest part of the substrate 22 after the grooves 31 are formed.

[0078] When forming the grooves 31, it is preferable to adjust the depth of the grooves 31 so that the thickness of the thinnest part of the substrate 22 is, for example, 10 μm or more. This allows the height 24h of the smooth surface 24 in the obtained electrode chip 20 to be, for example, 10 μm or more. Furthermore, it is possible to suppress the deterioration of the electrode film 21, and as a result, it is possible to reliably avoid a decrease in the sensor sensitivity in the sensor 10 having the electrode chip 20. Note that the "deterioration of the electrode film 21" referred to here means that the bond form between carbon atoms in the electrode film 21 becomes sp 3 Not a diamond bond structure, but sp 2 This means that it has a bonded structure (graphite structure).

[0079] Furthermore, when forming the grooves 31, it is more preferable to adjust the depth of the grooves 31 so that the thickness of the thinnest part of the substrate 22 is, for example, 250 μm or less, or to adjust the depth of the grooves 31 so that the thickness of the thinnest part of the substrate 22 is, for example, 80% or less of the thickness of the substrate 22 before the formation of the grooves 31. This improves the controllability when cleaving or splitting in step C described below, and makes it possible to divide the substrate 22 accurately, stably, and easily.

[0080] Furthermore, when forming the grooves 31, it is preferable to set the depth of the grooves 31 to, for example, 50 μm or more. This allows the height 25h of the non-smooth surface 25 in the obtained electrode tip 20 to be, for example, 50 μm or more.

[0081] In this step, it is also possible to form the grooves 31 from the surface (electrode film 21 side) of the laminated substrate 20a. However, since the electrode film 21 made of polycrystalline diamond has high hardness, it is difficult to form the grooves 31 from the surface of the laminated substrate 20a by laser processing, mechanical processing, or the like.

[0082] <Step B: Bonding the plate-shaped components> After forming the grooves 31, plate-like members having predetermined flexibility and hardness are attached to the front and back surfaces of the laminated substrate 20a using an adhesive or an adhesive member (for example, double-sided tape). The plate-like members may be made of a thin plastic plate or a flexible thin metal plate.

[0083] <Step C: Dividing the Conductive Substrate> Then, with plate-like members attached to the front and back surfaces of the laminated substrate 20a, stress is applied to the laminated substrate 20a from the substrate 22 side along the grooves 31 to introduce cracks into the substrate 22 that reach the interface between the electrode film 21 and the substrate 22, thereby cleaving or splitting the substrate 22. At this time, the cracks introduced into the substrate 22 are cracks that run along the cleavage or splitting direction.

[0084] After forming the grooves 31 in this way, the substrate 22 is cleaved or split to divide the substrate 22, and the resulting electrode chip 20 has a side surface 23 of the substrate 22 that has a melted or cut surface created by forming the grooves 31 and a cleaved or split surface created by cleaving or splitting the substrate 22. This melted or cut surface is a surface with Sa exceeding 1 μm, i.e., a non-smooth surface 25. Furthermore, this cleaved or split surface is a surface with Sa of 1 μm or less, i.e., a smooth surface 24. In this way, by splitting the substrate 22 using the above method, an electrode chip 20 can be obtained that has a side surface 23 that is composed of (only) the smooth surface 24 and the non-smooth surface 25.

[0085] Furthermore, when cleaving or splitting the substrate 22 with plate-like members bonded to the front and back surfaces of the laminated substrate 20a, it is preferable to cleave or split the substrate 22 while minimizing stress on the electrode film 21. This makes it easier to form a cleavage or split surface, i.e., a smooth surface 24, on (a part of) the side surface 23 of the substrate 22 in the resulting electrode chip 20. As a result, it becomes possible to form a belt-like smooth surface 24 that is continuous in the circumferential direction of the substrate 22 in the resulting electrode chip 20 with good reproducibility.

[0086] <Step D: Dividing the electrode film> After the substrate 22 is cleaved or split, stress is applied to the laminated substrate 20a from the electrode film 21 side with plate-like members attached to the front and back surfaces of the laminated substrate 20a, dividing the electrode film 21.

[0087] In this way, by dividing the substrate 22 after bonding plate-like members to the front and back surfaces of the laminated substrate 20a and then applying stress to the laminated substrate 20a from the electrode film 21 side to divide the electrode film 21, an electrode chip 20 can be obtained in which the height 24h of the smooth surface 24 is uniform and at least a portion of the upper edge 24t of the smooth surface 24, preferably the entire upper edge 24t of the smooth surface 24, is in contact with the upper edge 23t of the side surface 23.

[0088] Furthermore, by dividing the electrode film 21 after dividing the substrate 22 with plate-shaped members bonded to the front and back surfaces of the laminated substrate 20a, the electrode film 21 is less likely to peel off from the substrate 22 during division, making it easier to divide the electrode film 21 into a desired shape (intended shape). As a result, it is possible to obtain an electrode chip 20 in which the entire crystal growth surface of the substrate 22 is covered with the electrode film 21, i.e., an electrode chip 20 in which the crystal growth surface of the substrate 22 is not exposed. Furthermore, by being able to divide the electrode film 21 into an intended shape, it is possible to prevent variations in the planar shape of the electrode film 21 among multiple electrode chips 20 obtained from a single laminated substrate 20a. In other words, it is possible to make the area of ​​the top surface of the electrode film 21 uniform among multiple electrode chips 20. This makes it possible to prevent variations in sensor performance (e.g., sensor sensitivity) among multiple electrode chips 20, thereby improving the manufacturing yield and reliability of the electrode chips 20.

[0089] By dividing the multilayer substrate 20a by performing the above steps A to D in this order, the multilayer substrate 20a is divided into a plurality of small pieces. These small pieces then become the electrode chips 20.

[0090] By performing the above-mentioned steps A to D in this order to divide the laminated substrate 20a, an electrode chip 20 can be obtained, as shown in Figures 3 and 4, which has an electrode film 21 and a substrate 22, the side of the substrate 22 being composed of (only) a smooth surface 24 and a non-smooth surface 25, and the smooth surface 24 being formed in a belt shape that continues in the circumferential direction of the substrate 22.

[0091] Furthermore, by dividing the laminated substrate 20a by performing the above-described steps A to D in this order, it is possible to obtain an electrode chip 20 in which the non-smooth surface 25 is formed in a belt shape at least on the lower side of the smooth surface 24 of the side surface 23. Furthermore, the height 25h can be made uniform over the entire area of ​​the non-smooth surface 25.

[0092] Furthermore, by performing the above-mentioned steps A to D in this order to divide the laminated substrate 20a, it is possible to obtain an electrode chip 20 in which at least a portion of the upper edge 24t of the smooth surface 24, preferably the entire upper edge 24t, is in contact with the upper edge 23t of the side surface 23, and at least a portion of the lower edge 25b of the non-smooth surface 25, preferably the entire lower edge 25b, is in contact with the lower edge 23b of the side surface 23.

[0093] Alternatively, the laminated substrate 20a may be divided by cleaving or splitting the substrate 22 without performing step B, i.e., by separating the substrate 22 without bonding a plate-like member to the laminated substrate 20a. Alternatively, steps C and D may be simultaneously performed, i.e., by applying stress to the laminated substrate 20a from the substrate 22 side while the plate-like member is still bonded to the laminated substrate 20a, thereby simultaneously cleaving or splitting the substrate 22 (separating the substrate 22) and separating the electrode film 21. However, these methods cannot form a uniformly smooth surface 24 around the entire periphery of the side surface 23 of the substrate 22. In other words, the smooth surface 24 cannot be formed in a belt-like shape with a uniform height that continues in the circumferential direction of the substrate 22. Furthermore, variations in the area of ​​the upper surface of the electrode film 21 tend to occur among multiple electrode chips 20 obtained from a single laminated substrate 20a. In contrast, by the above-mentioned method of performing steps B to D in this order, i.e., with plate-shaped members attached to the front and back surfaces of the laminated substrate 20a, stress is applied to the laminated substrate 20a from the substrate 22 side to cleave or split the substrate 22, and then with plate-shaped members attached to the front and back surfaces of the laminated substrate 20a, stress is applied to the laminated substrate 20a from the electrode film 21 side to split the electrode film 21, these problems can be solved.

[0094] Another possible method is to dry-etch the laminated substrate 20a to form the electrode film 21 and the substrate 22 into a predetermined shape, and then divide the laminated substrate 20a. However, it is very difficult to divide the laminated substrate 20a, which has a high-hardness electrode film 21 made of polycrystalline diamond, into a predetermined shape by dry etching. Furthermore, dry etching may cause altered regions in the electrode film 21.

[0095] (Roughening) After dividing the electrode film 21 to divide the laminated substrate 20a, the plate-like members bonded to the front and back surfaces of the laminated substrate 20a are removed. Thereafter, if necessary, the small pieces of the divided laminated substrate 20a, i.e., the obtained electrode chips 20, may be further subjected to a surface roughening treatment. Specifically, the fused surface or cut surface formed by forming the grooves 31 on the side surface 23 of the substrate 22 of the electrode chip 20 may be further subjected to a surface roughening treatment. The surface roughening treatment is, for example, a process of roughening the fused surface or cut surface formed on the side surface 23 by rubbing (scraping) the fused surface or cut surface using abrasive grains or the like. This ensures that an uneven surface with Sa of more than 1 μm is formed on the side surface 23 of the substrate 22 of the electrode chip 20.

[0096] (Washing) After performing the roughening treatment as necessary, the small piece of laminated substrate 20a, i.e., the electrode chip 20, is washed to remove adhesive adhering to the surface of the electrode film 21 and chips generated by the roughening treatment.

[0097] [Fabrication of electrochemical sensors] Next, the sensor 10 is fabricated using the obtained electrode chip 20. Specifically, first, a support substrate 11 is prepared. Then, on the substrate 11, wirings 12 to 14 in a predetermined pattern, a reference electrode 17 electrically connected to wiring 13, and a counter electrode 18 electrically connected to wiring 14 are provided. Note that the substrate 11 may be prepared with the wirings 12 to 14, the reference electrode 17, and the counter electrode 18 already provided thereon. Furthermore, a conductive bonding material 15 is provided on the substrate 11 so as to be electrically connected to the wiring 12, and the electrode chip 20 is then placed on the bonding material 15. At this time, the electrode chip 20 is placed so that the electrode film 21 faces upward (i.e., so that the conductive substrate 22 faces the support substrate 11). As a result, the electrode chip 20 is fixed to the substrate 11 via the bonding material 15 and electrically connected to the wiring 12.

[0098] Then, the liquid resin is applied around the bonding material 15 and the electrode tip 20 so as to cover the bonding material 15 without exposing it and to cover part of the side surface 23. For example, the liquid resin is applied so as to cover the lower region of the side surface 23 of the substrate 22 of the bonding material 15 and the electrode tip 20. The liquid resin is then cured by heating or ultraviolet light irradiation. This provides the insulating resin 16 that seals the bonding material 15 and part of the side surface 23 of the substrate 22 of the electrode tip 20.

[0099] As described above, the side surface 23 of the substrate 22 of the electrode chip 20 is composed of a smooth surface 24 and a non-smooth surface 25, and the smooth surface 24 is formed in a belt shape. Because the liquid resin does not easily spread on the smooth surface 24, the liquid resin applied to the side surface 23 is unlikely to reach the electrode film 21. As a result, the liquid resin applied to the side surface 23 hardens while exposing the entire upper surface of the electrode film 21 and at least a portion of the smooth surface 24. On the other hand, the non-smooth surface 25 is fully wetted with the liquid resin, and therefore the non-smooth surface 25 has an anchor effect, which enhances adhesion between the insulating resin 16 and the side surface 23. As a result, the joint between the electrode chip 20 and the wiring 12 can be reliably sealed with the insulating resin 16. Furthermore, the fixing strength of the electrode chip 20 fixed to the substrate 11 via the bonding material 15 can be further enhanced.

[0100] Then, the wires 12 to 14 are covered with a waterproof member 19. In this way, the sensor 10 shown in FIGS.

[0101] (4) Effects According to this aspect, one or more of the following effects can be obtained.

[0102] (a) The side surface 23 of the substrate 22 of the electrode chip 20 is composed of a smooth surface 24 and a non-smooth surface 25, and the smooth surface 24 is formed in a belt shape, thereby preventing the liquid resin from spreading along the side surface 23 to the electrode film 21 and improving the adhesion between the insulating resin 26 and the side surface 23 (non-smooth surface 25). In other words, the electrode chip 20 according to this embodiment can simultaneously achieve a good balance between the effect of preventing resin spreading, the effect of resin sealing, and the effect of improving chip fixing strength.

[0103] The belt-shaped smooth surface 24 formed on the side surface 23 of the substrate 22 of the electrode chip 20 makes it difficult for the liquid resin applied to the side surface 23 to spread to the electrode film 21 during resin sealing in the manufacturing process of the sensor 10. In other words, a resin spread prevention effect can be obtained. This prevents the liquid resin from adhering to the electrode film 21, eliminates areas on the upper surface of the electrode film 21 that are contaminated by the insulating resin 16 adhering thereto, and allows the entire upper surface of the electrode film 21 to be exposed. As a result, a decrease in the sensor sensitivity of the sensor 10 can be avoided. For example, a decrease in the accuracy of measuring the concentration of uric acid in urine can be avoided.

[0104] The uneven surface 25 formed on the side surface 23 of the substrate 22 of the electrode chip 20 allows the uneven surface 25 to be sufficiently wetted with liquid resin during resin sealing in the manufacturing process of the sensor 10. This allows the periphery of the uneven surface 25 to be securely sealed with the insulating resin 16, thereby providing an insulating effect due to the insulating resin 16. Furthermore, the uneven surface 25 has an anchor effect, which can sufficiently increase the adhesion between the insulating resin 16 and the uneven surface 25. As a result, the fixing strength of the electrode chip 20 in the sensor 10 can also be increased. In other words, the effect of resin sealing and the effect of improving the chip fixing strength can be obtained.

[0105] (b) By forming the non-smooth surface 25 in a belt shape, it becomes easier to obtain the effect of resin sealing and the effect of improving the chip fixing strength.

[0106] (c) The non-smooth surface 25 is formed in a region of the side surface 23 that is lower than the smooth surface 24, thereby improving the adhesion in the lower region of the side surface 23. This makes it easier to obtain the resin sealing effect and the effect of improving the chip fixing strength.

[0107] (d) The non-smooth surface 25 is formed in a belt shape and is formed in a region of the side surface 23 below the smooth surface 24, so that the lower region of the side surface 23 is uniformly covered with the insulating resin 16 without being exposed, and the adhesion can be improved in the lower region of the side surface 23. As a result, the resin sealing effect and the effect of improving the chip fixing strength can be reliably obtained.

[0108] (e) By forming the smooth surface 24 in the upper region of the side surface 23 and the non-smooth surface 25 in the lower region of the side surface 23, it is possible to reliably obtain a balanced effect of preventing resin spreading, a resin sealing effect, and an effect of improving chip fixing strength at the same time.

[0109] (f) At least a portion of the upper edge 24t of the smooth surface 24 is in contact with the upper edge 23t of the side surface 23, thereby more reliably preventing the resin from spreading. Also, at least a portion of the lower edge 25b of the non-smooth surface 25 is in contact with the lower edge 23b of the side surface 23, thereby more reliably improving the resin sealing effect and the chip fixing strength.

[0110] (g) By making the height 24h of the smooth surface 24 10 μm or more, the resin spreading prevention effect can be more reliably achieved. Also, by making the height 25h of the non-smooth surface 25 50 μm or more, a highly wettable area can be sufficiently secured. This makes it possible to more reliably achieve the resin sealing effect and the effect of improving the chip fixing strength.

[0111] (h) By making the Sa of the smooth surface 24 1 μm or less, the wettability of the smooth surface 24 can be sufficiently low, and the effect of preventing the resin from spreading can be more reliably achieved. Also, by making the Sa of the non-smooth surface 25 greater than 1 μm, the wettability of the non-smooth surface 25 can be sufficiently high. This allows the non-smooth surface 25 to be sufficiently wetted with liquid resin during resin sealing in the manufacturing process of the sensor 10. As a result, the above-mentioned adhesion can be reliably improved, and the effect of resin sealing and the effect of improving chip fixing strength can be more reliably achieved.

[0112] (5) Variations This aspect can be modified as follows. In the following description of the modifications, the same components as those in the above aspect are denoted by the same reference numerals, and the description thereof will be omitted. The above aspect and the following modifications can be combined in any way.

[0113] (Variation 1) In the above-described embodiment, an example has been described in which the uneven surface 25 is formed in a belt shape that is continuous in the circumferential direction of the conductive substrate 22, but the present invention is not limited to this. For example, as shown in Fig. 7(a), the uneven surface 25 may be formed discontinuously in the circumferential direction of the substrate 22. The electrode chip 20 having such a side surface 23 can be obtained, for example, by forming grooves 31 by sweeping a laser beam while intermittently irradiating the rear surface of the substrate 22 with the laser beam in the above-described step A, and then performing the above-described steps B to D in this order.

[0114] In this modified example, the side surface 23 of the substrate 22 of the electrode chip 20 is composed of a smooth surface 24 and a non-smooth surface 25, and the smooth surface 24 is formed in a belt shape, so that the same effect as in the above-mentioned embodiment can be obtained. However, the case where the non-smooth surface 25 is formed in a belt shape as in the above-mentioned embodiment is preferable to this modified example in that it is easier to improve the adhesion between the insulating resin 16 and the side surface 23 (non-smooth surface 25), and it is easier to obtain the resin sealing effect and the chip fixing strength improvement effect.

[0115] (Variation 2) In the above-described aspect, an example has been described in which the non-smooth surface 25 is formed only in the region of the side surface 23 below the smooth surface 24, but the present invention is not limited to this. That is, the non-smooth surface 25 may be formed in at least the region of the side surface 23 below the smooth surface 24. For example, as shown in FIG. 7(b), the non-smooth surface 25 may be formed in the region of the side surface 23 below the smooth surface 24 and in the region above the smooth surface 24.

[0116] The electrode chip 20 having the side surface 23 as shown in FIG. 7(b) can be obtained, for example, by performing the above-described roughening treatment on the upper region of the smooth surface 24 (for example, the region of the smooth surface 24 in contact with the upper side 23t of the side surface 23) of the side surface 23 of the substrate 22 included in the electrode chip 20. In this case, the roughening treatment is performed so that the height 24h of the smooth surface 24 can be ensured to be 10 μm or more.

[0117] Also, the electrode chip 20 having the side surface 23 as shown in FIG. 7(b) may be obtained by performing the above-described steps A to D in this order in the manufacturing process of the electrode chip 20. Since the electrode film 21 made of polycrystalline diamond is very hard, when the substrate 22 is divided in step C, it becomes difficult to cleave or crack the substrate 22 directly below the electrode film 21. For this reason, a surface (that is, the non-smooth surface 25) having an arithmetic mean height (Sa) value exceeding 1 μm that is not a melted surface or a machined surface is unintentionally formed in the region of the side surface 23 above the smooth surface 24. As a result, an electrode chip 20 having a side surface 23 as shown in FIG. 7(b) may be obtained.

[0118] Also in this modified example, since the side surface 23 of the substrate 22 included in the electrode chip 20 is composed of the smooth surface 24 and the non-smooth surface 25, and the smooth surface 24 is formed in a belt shape, the same effects as those in the above-described aspect can be obtained.

[0119] (Modified Example 3) In the above-described embodiments and modifications, examples have been described in which the non-smooth surface 25 is formed in a region of the side surface 23 below the smooth surface 24, but the present invention is not limited to this. For example, as shown in Figures 7(c) and 7(d), the non-smooth surface 25 may be formed only in a region of the side surface 23 above the smooth surface 24. In this case, the non-smooth surface 25 may be formed in the shape of a belt that is continuous in the circumferential direction of the substrate 22, as shown in Figure 7(c), or may be formed discontinuously in the circumferential direction of the substrate 22, as shown in Figure 7(d).

[0120] In this modification, the side surface 23 of the substrate 22 of the electrode chip 20 is composed of a smooth surface 24 and a non-smooth surface 25, and the smooth surface 24 is formed in a belt shape, so that the resin spreading prevention effect can be obtained similarly to the above-mentioned embodiment. However, as shown in Figures 3, 4, 7(a), and 7(b), for example, forming the non-smooth surface 25 in a region below the smooth surface 24 is preferable to this modification in that it can increase the above-mentioned adhesion in the lower region of the side surface 23 and make it easier to obtain the resin sealing effect and the chip fixing strength improvement effect.

[0121] (Variation 4) In the above-described embodiments and modifications, examples have been described in which the boundary between the smooth surface 24 and the non-smooth surface 25 is a straight line, but the present invention is not limited to this. For example, as shown in Fig. 7(e), the boundary between the smooth surface 24 and the non-smooth surface 25 does not have to be a straight line. In this modification, the side surface 23 of the substrate 22 of the electrode tip 20 is composed of the smooth surface 24 and the non-smooth surface 25, and the smooth surface 24 is formed in a belt shape, so that the same effect as in the above-described embodiment can be obtained.

[0122] (Variation 5) 7(f), the non-smooth surface 25 may be formed in an island shape on the side surface 23. In this modification, the side surface 23 of the substrate 22 of the electrode tip 20 is composed of the smooth surface 24 and the non-smooth surface 25, and the smooth surface 24 is formed in a belt shape, so that at least the effect of preventing the resin from spreading can be obtained.

[0123] <Other aspects> Although the embodiments of the present disclosure have been specifically described above, the present disclosure is not limited to the above embodiments and can be modified in various ways without departing from the spirit and scope of the present disclosure.

[0124] For example, a functional membrane that allows only a predetermined detection target (e.g., uric acid) to pass through or that reacts only with the detection target may be provided on the electrode membrane 21. As such a functional membrane, a predetermined surface decoration membrane such as a membrane containing a predetermined enzyme corresponding to the detection component or an ion exchange membrane may be provided.

[0125] Furthermore, in the above-described embodiments and modifications, examples have been described in which the test liquid is human urine and the substance to be detected is uric acid, but the present invention is not limited to this. The test liquid may also be a body fluid, blood, urine, or the like, of an animal, including a human. That is, the sensor 10 (electrode chip 20) can be used by bringing a test liquid containing a body fluid, blood, or urine, of an animal, including a human, into contact with the electrode film 21. Furthermore, as long as the voltage applied to the electrode group (at least between the electrode chip 20 and the counter electrode 18) is within a predetermined voltage range, the concentration of various components (substances) other than uric acid can be measured by appropriately changing the voltage sweep conditions of cyclic voltammetry.

[0126] Furthermore, in the above-described embodiments and modifications, the sensor 10 is described as measuring the concentration of a detection target in a test liquid by a three-electrode method, but is not limited thereto. The sensor 10 may be configured to measure the concentration of a detection target in a test liquid by a two-electrode method. In other words, the reference electrode 17 and the wiring 13 may not be provided.

[0127] Furthermore, in the above-described embodiments and modifications, examples have been described in which the electrode chip 20 is used as the working electrode of the sensor 10, but the present disclosure is not limited thereto. The electrode chip 20 according to the present disclosure can be suitably used not only as the working electrode of the sensor 10, but also as an electrode (electrolysis electrode) for electrochemical electrolysis processes such as water treatment and wastewater treatment (wastewater treatment), or as an electrode (ozone generation electrode) for electrochemical ozone generation processes. As described above, in the electrode chip 20, the side surface 23 of the substrate 22 is composed of the smooth surface 24 and the non-smooth surface 25, and the smooth surface 24 is formed in a belt shape, so that the entire upper surface of the electrode film 21 can be exposed without being covered by the insulating resin 16. This enables electrochemical detection to be performed with high sensitivity, and electrolysis processes and ozone generation processes to be performed with high efficiency. [Example]

[0128] The following describes experimental results that support the effects of the above-described embodiment.

[0129] A plurality of single-crystal Si substrates were prepared as conductive substrates, each of which was subjected to a scratch treatment, and then an electrode film made of polycrystalline diamond was grown on each of the conductive substrates using the CVD apparatus shown in Figure 5, thereby producing a plurality of laminated substrates each having a conductive substrate and an electrode film. Each of the laminated substrates was then divided to produce electrode chips (Samples 1 to 4).

[0130] In Samples 1 to 3, when dividing the laminated substrate, steps A to D in the above-described embodiment were performed in this order. The conditions in steps A to D were set to predetermined conditions within the range of conditions described in the above-described embodiment. In Sample 4, when dividing the laminated substrate, in step A in the above-described embodiment, a concave groove was formed from the rear surface of the laminated substrate to a depth that reached the electrode film. The other conditions were the same as those in Samples 1 to 3.

[0131] FIG. 8 shows microscope images of the side surfaces of the conductive substrates of Samples 1 and 2, and FIG. 9 shows microscope images of the side surfaces of the conductive substrates of Samples 3 and 4. The arithmetic mean height (Sa) was also measured at multiple locations on the conductive substrates of Samples 1 to 4. The results are shown in FIGS. 8 and 9, respectively. From the microscope images and the Sa measurement results, it can be confirmed that Sample 1 has a side surface as shown in FIG. 3, and that Samples 2 and 3 have side surfaces as shown in FIG. 7(b). That is, it can be confirmed that the side surfaces of the conductive substrates of Samples 1 to 3 are composed of smooth and non-smooth surfaces, and that the smooth surfaces are formed in a belt shape. It can also be confirmed that the entire side surface of Sample 4 is composed of non-smooth surfaces.

[0132] Sensors were fabricated using Samples 1 to 4 by the method described in the above embodiment. Then, using these sensors, the uric acid concentration in urine was measured by cyclic voltammetry (CV). The CV measurement was performed under the same predetermined conditions within a voltage range including a range of -1 V to 1.5 V and a sweep rate range of 0.1 V / s to 1 V / s. The peak current values ​​obtained by the CV measurement were 109 μA for Sample 1, 116 μA for Sample 2, 137 μA for Sample 3, and 89 μA for Sample 4. The "peak current value" refers to the highest current value among the current values ​​obtained by the CV measurement.

[0133] As such, it can be confirmed that Samples 1 to 3 have higher peak current values ​​in CV measurements, i.e., higher sensor sensitivity, than Sample 4. This is thought to be because, as in Samples 1 to 3, the smooth, belt-like surface formed on the side of the conductive substrate prevents the liquid resin applied to the side of the conductive substrate of the sample from spreading to the electrode film during resin sealing in the sensor fabrication process, and therefore prevents the liquid resin from adhering to the surface of the electrode film.

[0134] <Preferred aspects of the present disclosure> Preferred aspects of the present disclosure will be described below.

[0135] (Appendix 1) According to one aspect of the present disclosure, a conductive substrate; an electrode film made of polycrystalline diamond provided on a crystal growth surface, which is one of the two main surfaces of the conductive substrate; and The side surface of the conductive substrate is formed with (only) two types of regions: a region formed with a smooth surface and a region formed with a non-smooth surface; An electrode tip is provided in which the smooth surface is formed in the shape of a belt that is continuous in the circumferential direction of the conductive substrate.

[0136] (Appendix 2) The electrode chip according to claim 1, preferably The non-smooth surface is formed in the shape of a belt that is continuous in the circumferential direction of the conductive substrate.

[0137] (Appendix 3) The electrode chip according to claim 1 or 2, preferably In the thickness direction of the conductive substrate, when the crystal growth surface side is the upper side and the main surface side different from the crystal growth surface is the lower side, the non-smooth surface is formed on at least the lower side of the smooth surface of the side surface.

[0138] (Appendix 4) The electrode chip according to any one of Supplementary Notes 1 to 3, preferably In the thickness direction of the conductive substrate, when the crystal growth surface side is the upper side and the main surface side different from the crystal growth surface is the lower side, the upper edge of the smooth surface (preferably, all upper edges of the smooth surface) is in contact with the upper edge of the conductive substrate.

[0139] (Appendix 5) The electrode chip according to any one of Supplementary Notes 1 to 4, preferably In the thickness direction of the conductive substrate, when the crystal growth surface side is the upper side and the main surface side different from the crystal growth surface is the lower side, the shortest vertical distance between the lower edge of the smooth surface and the upper edge of the smooth surface is 10 μm or more.

[0140] (Appendix 6) The electrode chip according to any one of Supplementary Notes 2 to 5, preferably In the thickness direction of the conductive substrate, when the crystal growth surface side is the upper side and the main surface side different from the crystal growth surface is the lower side, the lower edge of the non-smooth surface (preferably, all of the lower edges of the non-smooth surface) is in contact with the lower edge of the conductive substrate.

[0141] (Appendix 7) The electrode chip according to claim 6, preferably In the thickness direction of the conductive substrate, when the crystal growth surface side is the upper side and the main surface side different from the crystal growth surface is the lower side, the shortest vertical distance between the lower edge of the conductive substrate and the upper edge of the non-smooth surface is 50 μm or more.

[0142] (Appendix 8) The electrode chip according to any one of Supplementary Notes 1 to 7, preferably The smooth surface has an arithmetic mean height (Sa) of 1 μm or less.

[0143] (Appendix 9) The electrode chip according to any one of Supplementary Notes 1 to 8, preferably The non-smooth surface has an arithmetic mean height (Sa) of more than 1 μm.

[0144] (Appendix 10) The electrode chip according to any one of Supplementary Notes 1 to 9, preferably The smooth surface comprises a cleavage or splitting surface.

[0145] (Appendix 11) The electrode chip according to any one of Supplementary Notes 1 to 10, preferably The conductive substrate is made of a single crystal silicon substrate.

[0146] (Appendix 12) According to another aspect of the present disclosure, A support substrate; Electrical wiring arranged on the support substrate; an electrode tip connected to the electrical wiring via a conductive bonding material, the electrode tip having an electrode film made of a conductive substrate and polycrystalline diamond provided on a crystal growth surface, which is one of two main surfaces of the conductive substrate; an insulating resin that covers the bonding material and a portion of a side surface of the conductive substrate; and The side surface of the conductive substrate has two types of regions (only) formed thereon: a region formed of a smooth surface and a region formed of a non-smooth surface; the smooth surface is formed in a belt shape that is continuous in the circumferential direction of the conductive substrate, The electronic device is provided in which the entire upper surface of the electrode film and at least a part of the smooth surfaces of the side surfaces are exposed without being covered with the insulating resin.

[0147] (Appendix 13) The electronic device according to Supplementary Note 12, preferably In the thickness direction of the conductive substrate, when the crystal growth surface side is the upper side and the main surface side different from the crystal growth surface is the lower side, the non-smooth surface is formed in a belt shape that is continuous in a circumferential direction of the conductive substrate, and is formed on at least a portion of the side surface that is lower than the smooth surface, a region of the side surface below the smooth surface is covered with the insulating resin without being exposed, At least a part of the smooth surface is exposed without being covered with the insulating resin.

[0148] (Appendix 14) The electronic device according to Supplementary Note 12 or 13, preferably The insulating resin is a thermosetting resin or an ultraviolet curing resin.

[0149] (Appendix 15) According to yet another aspect of the present disclosure, A method for manufacturing an electrode tip having a conductive substrate and an electrode film made of polycrystalline diamond, comprising: a step of preparing a conductive substrate and a step of depositing polycrystalline diamond on a crystal growth surface, which is one of two main surfaces of the conductive substrate, to form an electrode film, thereby obtaining a laminated substrate; and dividing the laminated substrate, In the step of dividing the laminated substrate, After dividing the laminated substrate, two types of regions (only) are formed on the side surfaces of the conductive substrate, i.e., a region composed of a smooth surface and a region composed of a non-smooth surface, and the laminated substrate is divided so that the smooth surface is formed in a belt shape that is continuous in the circumferential direction of the conductive substrate. A method for manufacturing an electrode tip is provided.

[0150] (Appendix 16) According to yet another aspect of the present disclosure, a step of preparing a conductive substrate and a step of depositing polycrystalline diamond on a crystal growth surface, which is one of two main surfaces of the conductive substrate, to form an electrode film, thereby obtaining a laminated substrate; and dividing the laminated substrate, In the step of dividing the laminated substrate, forming a concave groove in one of two main surfaces of the conductive substrate of the laminated substrate, the main surface other than the crystal growth surface; a step of bonding plate-like members to the front and back surfaces of the laminated substrate using an adhesive or an adhesive member; a step of applying stress to the laminated substrate from the conductive substrate side along the concave grooves to cleave or split the conductive substrate, with plate-like members attached to the front and back surfaces of the laminated substrate; and a step of applying stress to the laminated substrate from the electrode film side to divide the electrode film in a state where plate-shaped members are attached to the front and back surfaces of the laminated substrate; Do the following in this order: A method for manufacturing an electrode tip is provided. [Explanation of symbols]

[0151] 10 Electrochemical sensors (electronic devices) 11 Support substrate 12~14 Electrical wiring 15 Bonding material 16 Insulating resin 20 electrode tips 21 Electrode membrane 22 Conductive substrate 23 Side of conductive substrate 24 Smooth surface 25 Unsmooth Surface

Claims

1. a conductive substrate; an electrode film made of polycrystalline diamond provided on a crystal growth surface, which is one of two main surfaces of the conductive substrate; and two types of regions, a region formed of a smooth surface and a region formed of a non-smooth surface, are formed on the side surface of the conductive substrate; the smooth surface is formed in a belt shape that is continuous in the circumferential direction of the conductive substrate, An electrode tip, wherein the height of the smooth surface, which is the distance between the lower and upper edges of the smooth surface in a direction perpendicular to the crystal growth surface, is greater than the height of the non-smooth surface, which is the distance between the lower and upper edges of the non-smooth surface in a direction perpendicular to the crystal growth surface.

2. The electrode tip according to claim 1 , wherein the non-smooth surface is formed in a belt shape that is continuous in the circumferential direction of the conductive substrate.

3. 3. The electrode chip according to claim 1, wherein, in the thickness direction of the conductive substrate, when the crystal growth surface side is the upper side and the main surface side different from the crystal growth surface is the lower side, the non-smooth surface is formed on at least the lower side of the smooth surface of the side surface.

4. An electrode chip according to any one of claims 1 to 3, wherein, in the thickness direction of the conductive substrate, when the crystal growth surface side is the upper side and the main surface side different from the crystal growth surface is the lower side, the upper edge of the smooth surface is in contact with the upper edge of the conductive substrate.

5. An electrode chip according to any one of claims 1 to 4, wherein, in the thickness direction of the conductive substrate, when the crystal growth surface side is the upper side and the main surface side different from the crystal growth surface is the lower side, the shortest vertical distance between the lower edge of the smooth surface and the upper edge of the smooth surface is 10 μm or more.

6. An electrode chip according to any one of claims 2 to 5, wherein, in the thickness direction of the conductive substrate, when the crystal growth surface side is the upper side and the main surface side different from the crystal growth surface is the lower side, the lower edge of the non-smooth surface is in contact with the lower edge of the conductive substrate.

7. 7. The electrode chip of claim 6, wherein, in the thickness direction of the conductive substrate, when the crystal growth surface side is the upper side and the main surface side different from the crystal growth surface is the lower side, the shortest vertical distance between the lower edge of the conductive substrate and the upper edge of the non-smooth surface is 50 μm or more.

8. 8. The electrode tip according to claim 1, wherein the smooth surface has an arithmetic mean height (Sa) of 1 μm or less.

9. The electrode tip according to any one of claims 1 to 8, wherein the non-smooth surface has an arithmetic mean height (Sa) of more than 1 µm.

10. 10. The electrode tip according to claim 1, wherein the smooth surface is formed by a cleavage plane or a split plane.

11. 11. The electrode tip according to claim 1, wherein the conductive substrate is made of a single crystal silicon substrate.

12. A support substrate; Electrical wiring arranged on the support substrate; an electrode tip connected to the electrical wiring via a conductive bonding material, the electrode tip having an electrode film made of a conductive substrate and a polycrystalline diamond film provided on a crystal growth surface, which is one of two main surfaces of the conductive substrate; an insulating resin that covers the bonding material and a portion of a side surface of the conductive substrate; and two types of regions, a region formed of a smooth surface and a region formed of a non-smooth surface, are formed on the side surface of the conductive substrate; the smooth surface is formed in a belt shape that is continuous in the circumferential direction of the conductive substrate, a height of the smooth surface, which is the distance between the lower edge and the upper edge of the smooth surface in a direction perpendicular to the crystal growth surface, is greater than a height of the non-smooth surface, which is the distance between the lower edge and the upper edge of the non-smooth surface in a direction perpendicular to the crystal growth surface; the entire upper surface of the electrode film and at least a part of the smooth surface of the side surface are exposed without being covered with the insulating resin.

13. In the thickness direction of the conductive substrate, when the crystal growth surface side is the upper side and the main surface side different from the crystal growth surface is the lower side, the non-smooth surface is formed in a belt shape that is continuous in a circumferential direction of the conductive substrate, and is formed on at least a portion of the side surface that is lower than the smooth surface, a region of the side surface below the smooth surface is covered with the insulating resin without being exposed, The electronic device according to claim 12 , wherein at least a part of the smooth surface is exposed without being covered with the insulating resin.

14. 14. The electronic device according to claim 12, wherein the insulating resin is a thermosetting resin or an ultraviolet curing resin.

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