Fluid chip and method for manufacturing a fluid chip

Abstract

To provide a fluid chip provided in an analyzer that analyzes traces of a sample, with which it is possible to realize the downsizing of this analyzer, and an analyzer equipped with this fluid chip.SOLUTION: A fluid chip 150 comprises an upstream passage 152 provided inside of an SOI substrate 151, a surface-side insulating film 133 provided on the surface of the SOI substrate 151, and an inflow opening 135 for allowing a sample to flow into the upstream passage 152 and provided in the surface-side insulating film 133. The upstream passage 152 includes a surface opening 152a provided on the surface of the SOI substrate 151, a reverse-side opening 152b provided on the reverse side of the SOI substrate 151, an aslant first inner wall 152c provided in an Si layer 151c of the SOI substrate 151, a vertical second inner wall 152d provided on a base substrate 151a of the SOI substrate 151, and a vertical third inner wall 152e provided in an insulating layer 151b of the SOI substrate 151.SELECTED DRAWING: Figure 36

Description

Technical Field

[0001] The present invention relates to a fluid chip and an analysis apparatus.

Background Art

[0002] As an analysis apparatus for analyzing a trace amount of a sample, there is known one including a fluid chip provided with a flow path having through holes (also referred to as nanopores) with a nano-sized diameter. For example, Patent Document 1 describes an analysis apparatus that uses a silicon substrate having nanopores with a diameter of several nm to several tens of nm provided in a flow path as a fluid chip to analyze a base sequence of DNA (Deoxyribonucleic Acid) or the like. The flow path penetrates the silicon substrate. Further, the inner wall of the flow path is inclined, and the opening on the surface side of the silicon substrate is smaller than the opening on the back side.

[0003] In Patent Document 1, the silicon substrate is provided between a supply unit to which DNA is supplied and a recovery unit from which DNA is recovered. The supply unit is connected to the flow path through an opening provided on the surface side of the silicon substrate. The recovery unit is connected to the flow path through an opening provided on the back side of the silicon substrate. Electrode pairs for performing electrophoresis of DNA are provided in the supply unit and the recovery unit. A voltage is applied to the electrode pairs, and analysis of a base sequence of DNA or the like is performed by measuring a change in the current value when DNA passes through the nanopore by electrophoresis.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in Patent Document 1, since the electrode pairs are provided so as to sandwich the silicon substrate from both sides, it is necessary to provide the holding members for holding the respective electrodes separately from each other, which is an obstacle to miniaturization of the analyzer.

[0006] An object of the present invention is to provide a fluid chip provided in an analyzer for analyzing a trace amount of a sample, which can achieve miniaturization of the analyzer, and an analyzer including the fluid chip.

Means for Solving the Problems

[0007] The fluid chip of the present invention includes a flow path inside the substrate provided inside the substrate, an insulating film provided on the surface of the substrate, an inflow opening provided upstream of the flow path inside the substrate for allowing a sample to flow into the flow path inside the substrate, and an outflow opening provided downstream of the flow path inside the substrate for allowing the sample to flow out from the flow path inside the substrate, wherein the inflow opening and the outflow opening are provided in the insulating film and are connected via the flow path inside the substrate.

[0008] Another fluid chip of the present invention includes a flow path inside the substrate provided inside the substrate, an insulating film provided on the surface of the substrate, and an inflow opening provided in the insulating film for allowing a sample to flow into the flow path inside the substrate, wherein the flow path inside the substrate has a front surface opening provided on the front surface of the substrate, a back surface opening provided on the back surface of the substrate, a first inner wall provided between the front surface opening and the back surface opening and inclined with respect to the back surface of the substrate, and a second inner wall provided downstream of the first inner wall between the front surface opening and the back surface opening and perpendicular to the back surface of the substrate.

[0009] Another fluid chip of the present invention includes a flow path inside the substrate provided inside the substrate, an insulating film provided on the surface of the substrate, an inflow opening provided in the insulating film for allowing a sample to flow into the flow path inside the substrate, and a conductive film provided in contact with the insulating film, wherein the conductive film has a conductive film opening connected to the inflow opening.

[0010] The analyzer of the present invention includes the above-described fluid chip, an upper sheet provided on the surface of the fluid chip, a supply unit to which the sample is supplied, and a recovery unit from which the sample is recovered. The upper sheet has a first upper flow path connecting the supply unit and the inflow opening, and a second upper flow path connecting the recovery unit and the outflow opening, and is characterized by forming a flow path for circulating the sample between the supply unit and the recovery unit.

[0011] Another analyzer of the present invention includes the above-described fluid chip, an upper sheet provided on the surface of the fluid chip, a lower sheet provided on the back surface of the fluid chip, a supply unit to which the sample is supplied, and a recovery unit from which the sample is recovered. The upper sheet has a first upper flow path connecting the supply unit and the inflow opening, and a second upper flow path connecting the recovery unit and the outflow opening. The in-substrate flow path has an upstream flow path connected to the inflow opening and a downstream flow path connected to the outflow opening. The lower sheet has a lower flow path connecting the upstream flow path and the downstream flow path, and is characterized by forming a flow path for circulating the sample between the supply unit and the recovery unit.

[0012] Another analyzer of the present invention includes a fluid chip having an in-substrate flow path penetrating a substrate provided with an insulating film on its surface, an upper sheet provided on the surface of the fluid chip, a lower sheet provided on the back surface of the fluid chip, a chip frame provided between the upper sheet and the lower sheet for holding the fluid chip, a supply unit to which the sample is supplied, and a recovery unit from which the sample is recovered. The upper sheet has a first upper flow path connected to the supply unit and a second upper flow path connected to the recovery unit. The chip frame has a connection hole connected to the second upper flow path. The insulating film is connected to the first upper flow path and has an inflow opening for allowing the sample to flow into the in-substrate flow path. The lower sheet has a lower flow path connecting the in-substrate flow path and the connection hole, and is characterized by forming a flow path for circulating the sample between the supply unit and the recovery unit.

Advantages of the Invention

[0013] According to the present invention, an inflow opening connected to a supply unit to which a sample is supplied and an outflow opening connected to a recovery unit from which the sample is recovered are provided on the same surface of a substrate, so that an electrode pair can be arranged on the same surface, and thus the analyzer can be miniaturized.

Brief Description of the Drawings

[0014]

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Embodiments for Carrying Out the Invention

[0015] [First Embodiment] As shown in FIG. 1, the fluid chip 10 is used in an analyzer 11 for analyzing a trace amount of sample. The analyzer 11 analyzes the sample by flowing a sample solution in which the sample is dispersed in a solution containing an electrolyte inside, and detecting a change in the current value when the sample passes through the fluid chip 10. Specifically, by applying a voltage to the electrode pair 15 described later, an ionic current is generated that flows through the internal space of the minimum opening with the smallest opening area among the flow paths of the sample flowing through the analyzer 11. The electrical resistance value of the minimum opening increases when the sample passes through the minimum opening. Therefore, the value of the ionic current changes according to the volume of the sample passing through the minimum opening. When a large volume of sample enters the internal space of the minimum opening, the value of the ionic current changes greatly, and when a small volume of sample enters the internal space of the minimum opening, the change in the value of the ionic current is small. In the analyzer 11, based on the change in the current value described above, analysis of the size and shape of the sample is performed. The sample is DNA (Deoxyribonucleic Acid), protein, pollen, virus, cell, organic particle or inorganic particle, particulate matter such as PM (Particulate Matter) 2.5, etc. In this example, it is DNA. In the present embodiment, since the inflow opening 22a of the fluid chip 10 described later is the minimum opening, the analyzer 11 identifies the nucleobase molecules constituting the DNA and analyzes the base sequence of the DNA by detecting the change in the current value when the DNA passes through the inflow opening 22a.

[0016] In addition to the fluid chip 10, the analyzer 11 includes an upper flow path sheet 12, a lower cover sheet 13, an upper cover sheet 14, and an electrode pair 15, and the fluid chip 10 is provided between the upper flow path sheet 12 and the lower cover sheet 13. Although details will be described later, the electrode pair 15 is provided in a supply unit 14a to which DNA is supplied and a recovery unit 14b from which DNA is recovered, and the supply unit 14a and the recovery unit 14b are provided on the same surface of the analyzer 11. In the present embodiment, the analyzer 11 further includes a chip frame 16 that holds the fluid chip 10. The planar shape of the analyzer 11 is, for example, rectangular, and in the present embodiment, it is a square with a side length of 25 mm.

[0017] The upper flow path sheet 12 is provided on the surface of the fluid chip 10. As the material of the upper flow path sheet 12, for example, rubber, resin, or the like is used. The upper flow path sheet corresponds to the "upper sheet" described in the claims.

[0018] The upper flow path sheet 12 has a first upper flow path 12a and a second upper flow path 12b. The first upper flow path 12a is connected to a supply unit 14a described later and guides the DNA supplied from the supply unit 14a to the fluid chip 10. The second upper flow path 12b is connected to a recovery unit 14b described later and guides the DNA from the fluid chip 10 to the recovery unit 14b. The shapes of the first upper flow path 12a and the second upper flow path 12b are not particularly limited, but are formed in a slit shape, for example.

[0019] The lower cover sheet 13 is provided on the back surface of the fluid chip 10. The lower cover sheet 13 constitutes the lower surface of the analyzer 11. As the material of the lower cover sheet 13, for example, rubber, resin, or the like is used.

[0020] The chip frame 16 has a housing portion 18 for housing the fluid chip 10. The housing portion 18 penetrates the chip frame 16 in the thickness direction. The shape of the housing portion 18 is formed according to the outer shape of the fluid chip 10. In this embodiment, the planar shape of the housing portion 18 is a square with a side length of 5 mm. As the material of the chip frame 16, for example, resin, or the like is used.

[0021] The upper cover sheet 14 is provided on the surface of the upper flow path sheet 12. As the material of the upper cover sheet 14, for example, rubber, resin, or the like is used. The upper cover sheet 14 constitutes the upper surface of the analyzer 11. A supply unit 14a and a recovery unit 14b are provided on the upper cover sheet 14. That is, the supply unit 14a and the recovery unit 14b are provided on the upper surface of the analyzer 11.

[0022] The electrode pair 15 is provided in the supply unit 14a and the recovery unit 14b. The electrode pair 15 is connected to a power source (not shown) and a current detection device. The power source applies a voltage to the electrode pair 15. When a voltage is applied to the electrode pair 15, electrophoresis of DNA is performed, and the DNA passes through the fluid chip 10. Note that the supplied DNA may pass through the fluid chip 10 by pressure, or may pass through the fluid chip 10 using a combination of electrophoresis and pressure. The current detection device detects a change in the current value by utilizing the fact that the current value changes when the DNA passes through the fluid chip 10.

[0023] The fluid chip 10 will be described with reference to FIGS. 1 and 2. The planar shape of the fluid chip 10 is, for example, rectangular, and in the present embodiment, it is a square with a side length of 5 mm (see FIG. 2). The fluid chip 10 includes a substrate 21, a front surface side insulating film 22, and a back surface side insulating film 23 (see FIG. 1).

[0024] The substrate 21 is a silicon substrate. The thickness of the substrate 21 is 775 μm in the present embodiment. A substrate internal flow path is provided inside the substrate 21. The substrate internal flow path guides the DNA supplied to the supply unit 14a to the recovery unit 14b. In the present embodiment, the substrate internal flow path has an upstream flow path 26, a downstream flow path 27, and a back surface flow path 28 (see FIG. 1).

[0025] The upstream flow path 26 is provided upstream of the substrate internal flow path. The upstream flow path 26 penetrates the substrate 21 in the thickness direction (see FIG. 1). The upstream flow path 26 has a front surface opening 26a provided on the front surface of the substrate 21, a back surface opening 26b provided on the back surface of the substrate 21, and an inner wall 26c connecting the front surface opening 26a and the back surface opening 26b. The inner wall 26c is inclined with respect to the back surface of the substrate 21. The inclination angle θ of the inner wall 26c is approximately 55°. As shown in FIG. 2, the planar shape of the front surface opening 26a is, for example, rectangular, and in the present embodiment, it is a square with a side length of 200 μm. The planar shape of the back surface opening 26b is, for example, rectangular, and in the present embodiment, it is a square. When the thickness of the substrate 21 is 775 μm, the side length of the back surface opening 26b is 1.2 mm.

[0026] The downstream flow path 27 is provided downstream of the in-substrate flow path. The downstream flow path 27 penetrates the substrate 21 in the thickness direction (see Fig. 1). The downstream flow path 27 has a front surface opening 27a provided on the front surface of the substrate 21, a back surface opening 27b provided on the back surface of the substrate 21, and an inner wall 27c connecting the front surface opening 27a and the back surface opening 27b. Similar to the inner wall 26c, the inner wall 27c is inclined with respect to the back surface of the substrate 21, and the inclination angle θ is approximately 55°. As shown in Fig. 2, the planar shape of the front surface opening 27a is, for example, rectangular, and in this embodiment, it is a square with a side length of 400 μm. The planar shape of the back surface opening 27b is, for example, rectangular, and in this embodiment, it is a square. When the thickness of the substrate 21 is 775 μm, the side length of the back surface opening 27b is 1.4 mm.

[0027] The back surface flow path 28 is provided on the back surface of the substrate 21 and connects the upstream flow path 26 and the downstream flow path 27 (see Fig. 1). The back surface flow path 28 guides the DNA in the upstream flow path 26 to the downstream flow path 27. The depth of the back surface flow path 28 is 35 μm in this embodiment. As shown in Fig. 2, the width W of the back surface flow path 28 is 50 μm in this embodiment.

[0028] The front surface side insulating film 22 is provided on the front surface of the substrate 21 (see Fig. 1). The front surface side insulating film 22 is formed of, for example, a SiN film (silicon nitride film), a SiO film (silicon oxide film), or the like. In this embodiment, the front surface side insulating film 22 is formed of a SiN film. The thickness of the front surface side insulating film 22 is 50 nm in this embodiment. The front surface side insulating film corresponds to the "insulating film" described in the claims.

[0029] The front surface side insulating film 22 is provided with an inflow opening 22a and an outflow opening 22b. In this embodiment, the inflow opening 22a and the outflow opening 22b are provided in the thickness direction of the fluid chip 10. The inflow opening 22a and the outflow opening 22b are connected via the in-substrate flow path of the substrate 21.

[0030] The inflow opening 22a is provided between the first upper channel 12a and the upstream channel 26, and allows the DNA in the first upper channel 12a to flow into the upstream channel 26 (see FIG. 1). That is, the inflow opening 22a is provided upstream of the in-substrate channel and allows DNA to flow into the in-substrate channel. The planar shape of the inflow opening 22a is, for example, circular. In this embodiment, the diameter of the inflow opening 22a is 200 nm (see FIG. 2).

[0031] The outflow opening 22b is provided between the second upper channel 12b and the downstream channel 27, and allows the DNA in the downstream channel 27 to flow out into the second upper channel 12b (see FIG. 1). That is, the outflow opening 22b is provided downstream of the in-substrate channel and allows DNA to flow out from the in-substrate channel. The planar shape of the outflow opening 22b is, for example, rectangular, and in this embodiment, it is a square with a side length of 400 μm (see FIG. 2).

[0032] The backside insulating film 23 is provided on the back surface of the substrate 21 (see FIG. 1). In this embodiment, the backside insulating film 23 is formed of a SiN film, similarly to the frontside insulating film 22, and has a thickness of 50 nm.

[0033] An upstream backside opening 23a, a downstream backside opening 23b, and a connection portion 23c are formed in the backside insulating film 23 (see FIG. 1). The upstream backside opening 23a is provided below the upstream channel 26. The downstream backside opening 23b is provided below the downstream channel 27. The connection portion 23c is provided between the upstream backside opening 23a and the downstream backside opening 23b and connects the upstream backside opening 23a and the downstream backside opening 23b. The planar shape of the upstream backside opening 23a is, for example, rectangular, and in this embodiment, it is a square with a side length of 1 mm (see FIG. 2). The planar shape of the downstream backside opening 23b is, for example, rectangular, and in this embodiment, it is a square with a side length of 1.4 mm. The width of the connection portion 23c is the same as the width W of the backside channel 28, and in this embodiment, it is 50 μm.

[0034] Hereinafter, a method for manufacturing the fluid chip 10 will be described with reference to FIGS. 3 to 5. The fluid chip 10 is manufactured by a surface pattern forming step, a back surface pattern forming step, and a substrate internal flow path forming step. FIGS. 3 to 5 are cross-sectional views taken along the line A-A of FIG. 2.

[0035] As shown in FIG. 3, in the surface pattern forming step, a surface pattern P1 is formed on an insulating film 31 provided on the surface of the substrate 30. As the substrate 30, a silicon substrate is used. The thickness of the substrate 30 is 775 μm in the present embodiment. In the surface pattern forming step, first, insulating films 31 are formed on both surfaces of the substrate 30. The insulating film 31 is formed, for example, by a CVD (Chemical Vapor Deposition) method using DCS (dichlorosilane) as a source gas. Then, a surface pattern P1 is formed on the insulating film 31 provided on the surface of the substrate 30, in which portions corresponding to the inflow opening 22a and the outflow opening 22b are open. For example, a photoresist is applied on the insulating film 31 provided on the surface of the substrate 30 to form a photoresist layer (not shown), and the photoresist layer is patterned by photolithography technology. A resist pattern is formed in the photoresist layer, in which portions corresponding to the inflow opening 22a and the outflow opening 22b are open. Using the photoresist layer with the resist pattern formed thereon as a mask, the insulating film 31 on the surface of the substrate 30 is dry-etched. Thereby, the surface pattern P1 is formed on the insulating film 31 on the surface side of the substrate 30. The insulating film 31 on which the surface pattern P1 is formed becomes the surface-side insulating film 22 of the fluid chip 10.

[0036] As shown in FIG. 4, in the back surface pattern forming step, a back surface pattern P2 is formed on the insulating film 31 and the protective film 32 provided on the back surface of the substrate 30. In the back surface pattern forming step, first, protective films 32 are formed on both surfaces of the substrate 30. The protective film 32 is preferably a material having a large etching rate selection ratio with respect to the wet etching solution in the anisotropic wet etching described later. The protective film 32 is, for example, a SiO film formed by a CVD method using TEOS (tetraethoxysilane) as a source gas. Thereafter, a back surface pattern P2 is formed on the insulating film 31 and the protective film 32 provided on the back surface of the substrate 30, in which portions corresponding to the back surface opening 26b of the upstream flow path 26, the back surface opening 27b of the downstream flow path 27, and the back surface flow path 28 are opened. The back surface pattern P2 is formed, for example, by the same method as the front surface pattern P1. That is, the back surface pattern P2 is formed by forming a photoresist layer (not shown) on the protective film 32 provided on the back surface of the substrate 30, patterning it by photolithography technology, and dry-etching the protective film 32 and the insulating film 31 on the back surface of the substrate 30 in this order using the photoresist layer on which the resist pattern is formed as a mask. The insulating film 31 on which the back surface pattern P2 is formed becomes the back surface side insulating film 23 of the fluid chip 10.

[0037] As shown in FIG. 5, in the substrate internal flow path forming step, a substrate internal flow path is formed inside the substrate 30. In the present embodiment, an upstream flow path 26, a downstream flow path 27, and a back surface flow path 28 are formed as the substrate internal flow paths. In the substrate internal flow path forming step, the substrate 30 that has undergone the back surface pattern forming step is immersed in a wet etching solution to perform anisotropic wet etching. As the wet etching solution, an alkaline aqueous solution such as KOH (potassium hydroxide) or TMAH (tetramethylammonium hydroxide) is used.

[0038] The protective film 32 formed on the back surface of the substrate 30 functions as a mask for anisotropic wet etching. Therefore, the substrate 30 is not etched on the surface entirely covered by the protective film 32, and only a part of the back surface exposed by the protective film 32 where the back surface pattern P2 is formed is etched. By performing anisotropic wet etching, an upstream flow path 26, a downstream flow path 27, and a back surface flow path 28 are formed in the substrate 30. The inclination angles θ of the inner walls 26c and 27c are determined based on the difference in the etching rates of the silicon crystal planes, and are approximately 55° in this embodiment. In a portion where the opening width of the protective film 32 where the back surface pattern P2 is formed is small, it is difficult for the wet etching liquid in the anisotropic wet etching to enter. In this embodiment, the opening width of the protective film 32 corresponding to the back surface flow path 28 is smaller than the opening widths of the protective film 32 corresponding to the back surface opening 26b of the upstream flow path 26 and the back surface opening 27b of the downstream flow path 27. Therefore, the back surface flow path 28 has a depth that does not penetrate the substrate 30 in the thickness direction. The depth of the back surface flow path 28 is controlled by adjusting the opening width of the protective film 32 corresponding to the portion of the back surface flow path 28. On the other hand, the upstream flow path 26 and the downstream flow path 27 penetrate the substrate 30 in the thickness direction. Since the protective film 32 is formed over the entire surface of the substrate 30, surface damage is suppressed and surface etching is prevented during anisotropic wet etching. The substrate 30 in which the upstream flow path 26, the downstream flow path 27, and the back surface flow path 28 are formed becomes the substrate 21 of the fluid chip 10. By removing the protective film 32 after anisotropic wet etching, the fluid chip 10 is obtained. The protective film 32 is removed, for example, by wet etching using HF (hydrofluoric acid) as the wet etching liquid.

[0039] The analysis device 11 is manufactured by attaching a lower cover sheet 13, an upper flow path sheet 12, and an upper cover sheet 14 to the fluid chip 10 manufactured through the above steps, and providing electrode pairs 15 in a supply section 14a and a recovery section 14b. In the analysis device 11, the DNA supplied to the supply section 14a flows in sequence through a first upper flow path 12a, the fluid chip 10, and a second upper flow path 12b, and is recovered at the recovery section 14b (see FIG. 1). The fluid chip 10 allows the DNA flowing into the inflow opening 22a from the first upper flow path 12a to pass through an upstream flow path 26 as an in-substrate flow path, a back surface flow path 28, and a downstream flow path 27 in sequence, and flow out from the outflow opening 22b to the second upper flow path 12b. In this way, the analysis device 11 forms a flow path for allowing DNA to pass between the supply section 14a and the recovery section 14b. In the analysis device 11, among the flow paths through which DNA flows, it is preferable that the opening area of the inflow opening 22a, which is the smallest opening, is sufficiently smaller than the opening areas of the other flow paths. By doing so, the difference between the electrical resistance value of the inflow opening 22a and the electrical resistance values of the other flow paths becomes sufficiently large, and analysis can be performed more reliably.

[0040] As described above, in the fluid chip 10, since the inflow opening 22a connected to the supply section 14a and the outflow opening 22b connected to the recovery section 14b are provided on the same surface of the substrate 21, the electrode pairs 15 provided in the supply section 14a and the recovery section 14b can be arranged on the same surface, so that the analysis device 11 can be miniaturized.

[0041] Since the fluid chip 10 can arrange the electrode pairs 15 on the surface side of the substrate 21, alignment of the electrode pairs 15 becomes easy. Further, in the fluid chip 10, since the upstream flow path 26 and the downstream flow path 27 are connected by the back surface flow path 28, there is no need to separately provide a member for connecting the upstream flow path 26 and the downstream flow path 27, so that the fluid chip 10 itself can be miniaturized.

[0042] In this example, the protective film 32 with the back surface pattern P2 is used as a mask for anisotropic wet etching. However, when the insulating film 31 functions as a mask material for anisotropic wet etching, the back surface pattern P2 may be formed on the insulating film 31 on the back surface of the substrate 30, and the protective film 32 may not be formed on the back surface of the substrate 30.

[0043] The diameter of the inflow opening 22a may be appropriately changed according to the sample. The planar shape of the inflow opening 22a is not limited to a circular shape, and may be an elliptical shape, a rectangular shape, a polygonal shape, etc.

[0044] The inclination angles of the inner wall 26c and the inner wall 27c are not limited to the case where θ = 55°, and can be set within the range of 0° < θ < 180°. The inner walls 26c and 27c are not limited to a planar shape, and may have a curved shape.

[0045] [Second Embodiment] In the first embodiment described above, the upstream flow path 26 and the downstream flow path 27 are connected by the back surface flow path 28. However, in the second embodiment, the upstream flow path 26 and the downstream flow path 27 are connected by a separately provided flow path sheet. In the following description, the same members as those in the first embodiment described above are denoted by the same reference numerals, and the description thereof is omitted.

[0046] As shown in FIG. 6, the fluid chip 40 is provided in the analyzer 41. The analyzer 41 includes, in addition to the fluid chip 40, an upper cover sheet 14, an upper flow path sheet 42, a lower flow path sheet 43, and a lower cover sheet 13. The planar shape of the analyzer 41 has a side length of 25 mm in this embodiment. In the second embodiment, a pair of supply portions 14a and 14d are provided at one diagonal position on the upper cover sheet 14, and a pair of recovery portions 14b and 14c are provided at the other diagonal position. Although not shown, the analyzer 41 includes an electrode pair 15, and for example, the electrode pair 15 is provided at the supply portion 14a and the recovery portion 14b.

[0047] The upper flow path sheet 42 is provided on the surface of the fluid chip 40. As the material of the upper flow path sheet 42, for example, rubber, resin, or the like is used.

[0048] The upper flow path sheet 42 has a first upper flow path 42a and second upper flow paths 42b and 42c. The shapes of the first upper flow path 42a and the second upper flow paths 42b and 42c are not particularly limited, but in the present embodiment, they are formed in a slit shape. The first upper flow path 42a is provided diagonally on one side of the analyzer 41 and connects the supply section 14a and the supply section 14d. The second upper flow paths 42b and 42c are provided at intervals diagonally on the other side of the analyzer 41. The second upper flow path 42b is connected to the recovery section 14b. The second upper flow path 42c is connected to the recovery section 14c.

[0049] The lower flow path sheet 43 is provided on the back surface of the fluid chip 40. The lower flow path sheet 43 has a lower flow path 44. The lower flow path 44 is provided diagonally on the other side of the analyzer 41 and connects the first upper flow path 42a and the second upper flow paths 42b and 42c via the fluid chip 40. As the material of the lower flow path sheet 43, for example, rubber, resin, or the like is used. The shape of the lower flow path 44 is not particularly limited, but in the present embodiment, it is formed in a slit shape. The lower flow path sheet corresponds to the "lower sheet" described in the claims.

[0050] In the analysis device 41, when filling the first upper channel 42a with the sample liquid, for example, the supply part 14d is used as a vent hole, and the sample liquid is injected from the supply part 14a to fill the first upper channel 42a with the sample liquid. On the other hand, when filling the second upper channels 42b and 42c and the lower channel 44 with the sample liquid, for example, the recovery part 14c is used as a vent hole, and the sample liquid is injected from the recovery part 14b to fill the second upper channel 42b, the lower channel 44, and the second upper channel 42c with the sample liquid in this order. When performing the analysis, the supply part 14d and the recovery part 14c where the electrode pair 15 (not shown) is not provided are blocked by a sealing member or the like (not shown), and the flow of the sample is restricted. Note that when filling the first upper channel 42a with the sample liquid, the supply part 14a may be used as a vent hole, and the sample liquid may be injected from the supply part 14d. When filling the second upper channels 42b and 42c and the lower channel 44 with the sample liquid, the recovery part 14b may be used as a vent hole, and the sample liquid may be injected from the recovery part 14c. The electrode pair 15 is not limited to being provided at the supply part 14a and the recovery part 14b, and may be provided at any of the supply part 14a and the recovery part 14c, the supply part 14d and the recovery part 14b, and the supply part 14d and the recovery part 14c.

[0051] As shown in FIG. 7, the fluid chip 40 includes a front surface side insulating film 22, a back surface side insulating film 52, and a substrate 53. The back surface side insulating film 52 has an upstream back surface opening 23a and a downstream back surface opening 23b. The back surface side insulating film 52 is different from the back surface side insulating film 23 of the first embodiment in that it does not have a connection part 23c. The substrate 53 has an upstream channel 26 and a downstream channel 27 as internal channels of the substrate. The substrate 53 is different from the substrate 21 of the first embodiment in that it does not have a back surface channel 28. Although not shown in this figure, the fluid chip 40 is provided with a connection hole 54 (see FIG. 6) that penetrates the fluid chip 40 in the thickness direction and connects the second upper channel 42c and the lower channel 44.

[0052] In the fluid chip 40 having the above configuration, the DNA in the first upper channel 42a passes through the inflow opening 22a, and then passes through the outflow opening 22b through the upstream channel 26, the lower channel 44, and the downstream channel 27 in sequence, thereby moving to the second upper channel 42b. Therefore, the analyzer 41 forms a flow path through which DNA passes between the supply unit 14a and the recovery unit 14b.

[0053] In the fluid chip 40, similar to the fluid chip 10 of the first embodiment, since the inflow opening 22a and the outflow opening 22b are provided on the same surface of the substrate 53, the electrode pair can be arranged on the same surface, so that the analyzer 41 can be miniaturized.

[0054] Note that the analyzer 41 may use the fluid chip 60 shown in FIG. 8 instead of the fluid chip 40. The fluid chip 60 includes a front-side insulating film 61, a back-side insulating film 62, and a substrate 63. The front-side insulating film 61 has an inflow opening 22a. The front-side insulating film 61 is different from the front-side insulating film 22 of the first embodiment in that it does not have an outflow opening 22b. The back-side insulating film 62 has an upstream back opening 23a. The back-side insulating film 62 is different from the back-side insulating film 23 of the first embodiment in that it does not have a downstream back opening 23b and a connection portion 23c. The substrate 63 has an upstream channel 26. The substrate 63 is different from the substrate 21 of the first embodiment in that it does not have a downstream channel 27 and a back channel 28. That is, in the fluid chip 60, the upstream channel 26 is an in-substrate channel.

[0055] The fluid chip 60 is held by a chip frame 64. The chip frame 64 has a housing portion 65 that houses the fluid chip 60 and a connection hole 66 that connects the lower channel 44 and the second upper channel 42b. The housing portion 65 and the connection hole 66 penetrate the chip frame 64 in the thickness direction. In the fluid chip 60, the DNA in the first upper channel 42a passes through the inflow opening 22a, and then moves to the second upper channel 42b through the upstream channel 26, the lower channel 44, and the connection hole 66 in sequence. In the fluid chip 60, similar to the fluid chips 10 and 40, the electrode pair can be arranged on the same surface, so that the analyzer 41 can be miniaturized.

[0056] [Embodiment 3] In Embodiment 3, a reinforcing film for reinforcing the surface-side insulating film is provided between the surface-side insulating film and the substrate. In Embodiment 3, for the components that use the same members as in Embodiment 2, the same reference numerals are given and the description is omitted. Further, in Embodiment 3, the description will be made by focusing on the portion where the upstream flow path 26 as the in-substrate flow path is provided, and the illustration and description of the portion where the downstream flow path 27 is provided are omitted.

[0057] As shown in FIG. 9, the fluid chip 70 further includes a reinforcing film 74 provided between the surface-side insulating film 22 and the substrate 53, in addition to the surface-side insulating film 22, the back-side insulating film 52, and the substrate 53. The reinforcing film 74 is a thermal oxidation film formed, for example, by thermally oxidizing silicon. The thickness of the reinforcing film 74 is 500 nm in this embodiment. In Embodiment 3, the diameter of the inflow opening 22a is 400 nm.

[0058] A through-hole 75 that connects the inflow opening 22a and the upstream flow path 26 is formed in the reinforcing film 74. The through-hole 75 has a first opening 76 provided on the front surface of the reinforcing film 74 and a second opening 77 provided on the back surface of the reinforcing film 74, and penetrates the reinforcing film 74 in the thickness direction. The first opening 76 is connected to the inflow opening 22a. In this example, the inner wall surface of the first opening 76 is inclined with respect to the film surface of the reinforcing film 74, and the opening area of the first opening 76 becomes larger from the front surface to the back surface of the reinforcing film 74. The second opening 77 is connected to the upstream flow path 26. The first opening 76 is larger than the inflow opening 22a, and the inner wall surface recedes from the opening end of the inflow opening 22a. Also, the first opening 76 is smaller than the second opening 77. The second opening 77 is larger than the surface opening 26a of the upstream flow path 26, and the inner wall surface recedes from the opening end of the surface opening 26a. The recession amount of the second opening 77 is larger than the recession amount of the first opening 76. In this embodiment, the recession amount of the first opening 76 is 175 nm, and the recession amount of the second opening 77 is 300 nm. Also, the depth of the first opening 76 is 200 nm, and the depth of the second opening 77 is 300 nm. Although not shown, a through-hole that connects the outflow opening 22b and the downstream flow path 27 is formed in the reinforcing film 74.

[0059] In the third embodiment, the fluid chip 70 further includes a reinforcing film 78 provided between the back surface insulating film 52 and the substrate 53. The reinforcing film 78 is a thermal oxide film formed by thermally oxidizing silicon, similar to the reinforcing film 74, and has a thickness of 500 nm. A through hole 79 connecting the upstream back surface opening 23a and the upstream flow path 26 is formed in the reinforcing film 78. The through hole 79 penetrates the reinforcing film 78 in the thickness direction. The through hole 79 is larger than the upstream back surface opening 23a and the back surface opening 26b, and the inner wall surface recedes from the opening ends of the upstream back surface opening 23a and the back surface opening 26b. Although not shown, a through hole connecting the downstream back surface opening 23b and the downstream flow path 27 is formed in the reinforcing film 78.

[0060] A method for manufacturing the fluid chip 70 will be described with reference to FIGS. 10 to 13. The fluid chip 70 is manufactured by a preparation process, a surface pattern formation process, a back surface pattern formation process, and a substrate internal flow path formation process.

[0061] As shown in FIG. 10, in the preparation process, a reinforcing film 81 and an insulating film 82 are sequentially formed on both surfaces of the substrate 80. As the substrate 80, a silicon substrate is used. The thickness of the substrate 80 is 775 μm in this embodiment. The reinforcing film 81 is formed, for example, by a thermal CVD method of oxidizing silicon in an oxygen atmosphere. The insulating film 82 is formed, for example, by a CVD method using DCS as a source gas.

[0062] As shown in Fig. 11, in the surface pattern forming step, a surface pattern P1 is formed on the reinforcing film 81 and the insulating film 82 provided on the surface of the substrate 80. The surface pattern P1 is formed, for example, by forming a photoresist layer (not shown) on the insulating film 82 on the surface side of the substrate 80, patterning it by photolithography technology, and dry-etching the insulating film 82 and the reinforcing film 81 on the surface of the substrate 80 in order using the patterned photoresist layer as a mask. In the reinforcing film 81 and the insulating film 82 on which the surface pattern P1 is formed, portions corresponding to the inflow opening 22a and the outflow opening 22b are open. The insulating film 82 on which the surface pattern P1 is formed becomes the surface-side insulating film 22 of the fluid chip 70.

[0063] As shown in Fig. 12, in the back surface pattern forming step, a back surface pattern P2 is formed on the reinforcing film 81, the insulating film 82, and the protective film 84 provided on the back surface of the substrate 80. In the back surface pattern forming step, first, protective films 84 are formed on both surfaces of the substrate 80. The protective film 84 is preferably a material having an etching rate selection ratio with respect to the wet etching liquid in the wet etching for forming the through portions 75 and 79 described later, which is larger than that of the reinforcing film 81. The protective film 84 is formed, for example, by a CVD method using TEOS as a source gas. The protective film 84 is embedded in each opening of the reinforcing film 81 and the insulating film 82 on which the surface pattern P1 is formed. The thickness of the protective film 84 is 500 nm in this embodiment. After forming the protective films 84 on both surfaces of the substrate 80, a back surface pattern P2 is formed on the reinforcing film 81, the insulating film 82, and the protective film 84 on the back surface side of the substrate 80. The back surface pattern P2 is formed, for example, in the same manner as the surface pattern P1. In the case of this embodiment, in the reinforcing film 81, the insulating film 82, and the protective film 84 on which the back surface pattern P2 is formed, portions corresponding to the back surface opening 26b of the upstream flow path 26 and the back surface opening 27b of the downstream flow path 27 are open. The insulating film 82 on which the back surface pattern P2 is formed becomes the back surface-side insulating film 52 of the fluid chip 70.

[0064] As shown in FIG. 13, in the substrate internal flow path forming step, a substrate internal flow path is formed inside the substrate 80. In the case of this embodiment, the substrate internal flow path includes an upstream flow path 26 and a downstream flow path 27 (not shown). The formation of the downstream flow path 27 will be omitted from the description. The substrate internal flow path is formed, for example, by anisotropic wet etching using an alkaline aqueous solution. The protective film 84 functions as a mask for anisotropic wet etching. The substrate 80 in which the substrate internal flow path is formed becomes the substrate 53 of the fluid chip 70.

[0065] After the substrate internal flow path forming step, the protective film 84 is removed by wet etching. For example, the substrate 80 in which the upstream flow path 26 is formed is immersed in a wet etching solution. The wet etching solution is HF or the like. Since the opening on the surface side of the substrate 80 is blocked by the protective film 84, the wet etching solution flows into the upstream flow path 26 from the opening on the back side of the substrate 80. In the process of removing the protective film 84 by wet etching, a part of the reinforcing film 81 is also removed. The reinforcing film 81 provided on the surface of the substrate 80 is etched from the back side by the wet etching solution that has flowed into the upstream flow path 26. By this wet etching, the protective film 84 is removed, an opening corresponding to the through hole 75 is formed in the reinforcing film 81 on the surface of the substrate 80, and an opening corresponding to the through hole 79 is formed in the reinforcing film 81 on the back surface of the substrate 80. The recession amounts of the through hole 75 and the through hole 79 can be controlled by the thickness of the reinforcing film 81 and the etching rate selection ratio of the reinforcing film 81 with respect to the wet etching solution. The reinforcing film 81 in which the opening corresponding to the through hole 75 is formed becomes the reinforcing film 74 of the fluid chip 70. The reinforcing film 81 in which the opening corresponding to the through hole 79 is formed becomes the reinforcing film 78 of the fluid chip 70. As a result, the fluid chip 70 shown in FIG. 9 is obtained. Note that when a part of the reinforcing film 81 is not removed in the process of wet etching the protective film 84, it is preferable to separately perform wet etching for removing a part of the reinforcing film 81. Since the surface side insulating film 22 of the fluid chip 70 is reinforced by the reinforcing film 78, damage to the surface side insulating film 22 and the like are suppressed, and the durability is excellent.

[0066] In the surface pattern formation step, the surface pattern P1 may be formed only on the insulating film 82 out of the reinforcing film 81 and the insulating film 82 provided on the surface of the substrate 80. In this case, the opening area of the first opening 76 becomes smaller as it goes from the front surface side to the back surface side of the reinforcing film 74. The inner wall surface of the first opening 76 has, for example, a convexly curved shape facing outward. The amount of recession from the opening end of the inflow opening 22a at the connection portion where the first opening 76 and the second opening 77 are connected is smaller than the amount of recession of the first opening 76. For example, the amount of recession of the first opening 76 is set to 300 nm, and the amount of recession at the connection portion between the first opening 76 and the second opening 77 is set to 230 nm.

[0067] In the back surface pattern formation step, the protective film 84 may not be formed. When the protective film 84 is not formed, it is preferable that the insulating film 82 functions as a mask material for anisotropic wet etching in the substrate internal flow path formation step. In the wet etching after the substrate internal flow path formation step, the amount of recession of the first opening 76 and the amount of recession of the second opening 77 are substantially the same. For example, the amount of recession of each of the first opening 76 and the second opening 77 is set to 300 nm.

[0068] [Fourth Embodiment] In each of the above embodiments, the inflow opening is provided in the thickness direction of the fluid chip. However, in the fourth embodiment, the inflow opening is provided in a direction different from the thickness direction of the fluid chip.

[0069] As shown in FIG. 14, the fluid chip 90 is provided in the analyzer 11 instead of the fluid chip 10 of the first embodiment. The fluid chip 90 has a front surface side insulating film 91 provided on the surface of the substrate 21 and a back surface side insulating film 23 provided on the back surface of the substrate 21. The front surface side insulating film 91 is formed of, for example, a SiN film. Through holes 91a connected to the upstream flow path 26 and through holes 91b connected to the downstream flow path 27 are formed in the front surface side insulating film 91.

[0070] An insulating film 92 is provided on the surface of the surface-side insulating film 91. The insulating film 92 is formed of, for example, a SiN film. The insulating film 92 has an inflow opening 92a provided between the first upper flow path 12a and the through hole 91a, and an outflow opening 92b provided between the second upper flow path 12b and the through hole 91b. The outflow opening 92b is provided in the thickness direction of the fluid chip 90 and is the same as that in the first embodiment, so the description thereof is omitted.

[0071] The inflow opening 92a is provided in a direction different from the thickness direction of the fluid chip 90, which is different from the inflow opening 22a of the first embodiment. In this example, the inflow opening 92a is provided in a direction orthogonal to the thickness direction of the fluid chip 90. In the fourth embodiment, the minimum opening in the sample flow path is the inflow opening 92a.

[0072] With reference to FIGS. 15A to C and FIGS. 19A to C, an example of a method for forming the inflow opening 92a will be described. In the following description, attention will be paid to the portion of the fluid chip 90 where the inflow opening 92a is formed. The inflow opening 92a is formed by a first insulating film forming step, a second insulating film forming step, a third insulating film forming step, an insulating film processing step, and an insulating film removing step.

[0073] As shown in FIGS. 15A to C, in the first insulating film forming step, after forming the surface-side insulating film 91 on the substrate 21, a first insulating film 95 is formed on the surface of the surface-side insulating film 91. FIG. 15A is a plan view, FIG. 15B is a cross-sectional view taken along line B-B of FIG. 15A, and FIG. 15C is a cross-sectional view taken along line C-C of FIG. 15A. The surface-side insulating film 91 and the first insulating film 95 can be formed by the same method, for example, by a CVD method using DCS as a source gas.

[0074] As shown in FIGS. 16A to 16C, in the second insulating film forming step, a groove 96 is formed in the first insulating film 95, and a second insulating film 97 is formed in this groove 96. FIG. 16A is a plan view, FIG. 16B is a cross-sectional view taken along line B-B of FIG. 16A, and FIG. 16C is a cross-sectional view taken along line C-C of FIG. 16A. As shown in FIG. 16A, the planar shape of the groove 96 is, for example, rectangular. The length of the short side of the groove 96 is the length in the width direction orthogonal to the thickness direction at the inflow opening 92a, that is, the width of the inflow opening 92a. The depth of the groove 96 is the length in the thickness direction at the inflow opening 92a, that is, the height of the inflow opening 92a. The groove 96 is formed, for example, by applying a photoresist on the surface of the first insulating film 95 to form a photoresist layer (not shown), patterning it by photolithography technology, and dry-etching the first insulating film 95 using the photoresist layer with the resist pattern formed as a mask. After the formation of the groove 96, an SiO film is formed over the entire surface of the first insulating film 95 by, for example, CVD method using TEOS as a source gas. Next, the surface of the SiO film is planarized. For planarization, for example, a CMP (Chemical Mechanical Polishing) apparatus is used. The planarization is preferably performed so that the surface of the first insulating film 95 is exposed. By the planarization, the SiO film on the surface of the first insulating film 95 is removed, and the second insulating film 97 is formed by the SiO film remaining in the groove 96.

[0075] As shown in FIGS. 17A to 17C, in the third insulating film forming step, a third insulating film 98 is formed on the surfaces of the first insulating film 95 and the second insulating film 97. FIG. 17A is a plan view, FIG. 17B is a cross-sectional view taken along line B-B of FIG. 17A, and FIG. 17C is a cross-sectional view taken along line C-C of FIG. 17A. The third insulating film 98 is formed, for example, by CVD method using DCS as a source gas.

[0076] As shown in FIGS. 18A to 18C, in the insulating film processing step, the first insulating film 95, the second insulating film 97, and the third insulating film 98 are processed to form a plate-like body 99. FIG. 18A is a plan view, FIG. 18B is a cross-sectional view taken along line B-B of FIG. 18A, and FIG. 18C is a cross-sectional view taken along line C-C of FIG. 18A. The planar shape of the plate-like body 99 shown in FIG. 18A is rectangular. The length of the short side of the plate-like body 99 is the length in the direction orthogonal to the thickness direction and the width direction in the inflow opening 92a, that is, the length of the inflow opening 92a. In the insulating film processing step, for example, dry etching is performed.

[0077] As shown in FIGS. 19A to 19C, in the insulating film removing step, the second insulating film 97 is removed from the plate-like body 99. FIG. 19A is a plan view, FIG. 19B is a cross-sectional view taken along line B-B of FIG. 19A, and FIG. 19C is a cross-sectional view taken along line C-C of FIG. 19A. In the second insulating film removing step, for example, wet etching using HF as a wet etching solution is performed. Among the plate-like body 99, the second insulating film 97 is removed, and the first insulating film 95 and the third insulating film 98 remain. The plate-like body 99 formed by the remaining first insulating film 95 and third insulating film 98 becomes the inflow opening 92a. The opening area of the inflow opening 92a is determined by the length of the short side of the groove 96 and the depth of the groove 96. Among the length of the short side of the groove 96 and the depth of the groove 96, the depth of the groove 96 can be made equal to or less than the minimum processing dimension of the photolithography technique. Therefore, the fluid chip 90 is excellent in the degree of freedom of design of the inflow opening 92a as the minimum opening.

[0078] Note that the fluid chip 90 may be provided with an inflow opening 102 shown in FIGS. 20A to 20C instead of the inflow opening 92a. FIG. 20A is a plan view, FIG. 20B is a cross-sectional view taken along line B-B of FIG. 20A, and FIG. 20C is a cross-sectional view taken along line C-C of FIG. 20A. The method of forming the inflow opening 102 will be described with reference to FIGS. 21A to 21C to FIGS. 27A to 27C. The inflow opening 102 is formed by a first insulating film forming step, a second insulating film forming step, a third insulating film forming step, a groove forming step, a fourth insulating film forming step, a fifth insulating film forming step, an insulating film processing step, and an insulating film removing step.

[0079] As shown in FIGS. 21A to 21C, in the first insulating film forming step, a first insulating film 105 is formed on the surface of the surface-side insulating film 91. FIG. 21A is a plan view, FIG. 21B is a cross-sectional view taken along line B-B of FIG. 21A, and FIG. 21C is a cross-sectional view taken along line C-C of FIG. 21A. In the first insulating film forming step, for example, an SiO film is formed over the entire surface of the surface-side insulating film 91 by CVD using TEOS as a source gas, and a part of the SiO film is removed by dry etching to form the first insulating film 105.

[0080] As shown in FIGS. 22A to 22C, in the second insulating film forming step, a second insulating film 106 is formed on the surface of the surface-side insulating film 91 and the surface of the first insulating film 105. FIG. 22A is a plan view, FIG. 22B is a cross-sectional view taken along line B-B of FIG. 22A, and FIG. 22C is a cross-sectional view taken along line C-C of FIG. 22A. The second insulating film 106 is formed, for example, by CVD using DCS as a source gas. The second insulating film 106 is formed in a stepped shape, and the portion formed on the surface of the surface-side insulating film 91 is one step lower than the portion formed on the surface of the first insulating film 105.

[0081] As shown in FIGS. 23A to 23C, in the third insulating film forming step, a third insulating film 107 is formed on the surface of the second insulating film 106. FIG. 23A is a plan view, FIG. 23B is a cross-sectional view taken along line B-B of FIG. 23A, and FIG. 23C is a cross-sectional view taken along line C-C of FIG. 23A. In the third insulating film forming step, for example, an SiO film is formed over the entire surface of the second insulating film 106 by CVD using TEOS as a source gas, and the surface of the SiO film is planarized by a CMP apparatus to form the third insulating film 107. By planarization, the portion formed on the surface of the first insulating film 95 in the second insulating film 106 is exposed. The third insulating film 107 is formed by the SiO film remaining on the portion formed on the surface of the surface-side insulating film 91 in the second insulating film 106.

[0082] As shown in FIGS. 24A to 24C, in the groove formation step, the groove 108 is formed by partially removing the first insulating film 105, the second insulating film 106, and the third insulating film 107. FIG. 24A is a plan view, FIG. 24B is a cross-sectional view taken along line B-B of FIG. 24A, and FIG. 24C is a cross-sectional view taken along line C-C of FIG. 24A. In the groove formation step, for example, dry etching is performed.

[0083] As shown in FIGS. 25A to 25C, in the fourth insulating film formation step, the fourth insulating film 109 is formed in the groove 108. FIG. 25A is a plan view, FIG. 25B is a cross-sectional view taken along line B-B of FIG. 25A, and FIG. 25C is a cross-sectional view taken along line C-C of FIG. 25A. In the fourth insulating film formation step, for example, the fourth insulating film 109 is formed in the groove 108 by performing a CVD method using TEOS as a source gas and planarization using a CMP apparatus. The fourth insulating film 109 is formed of a SiO film.

[0084] As shown in FIGS. 26A to 26C, in the fifth insulating film formation step, the fifth insulating film 110 is formed on the flat surface formed by the second insulating film 106, the third insulating film 107, and the fourth insulating film 109. FIG. 26A is a plan view, FIG. 26B is a cross-sectional view taken along line B-B of FIG. 26A, and FIG. 26C is a cross-sectional view taken along line C-C of FIG. 26A. The fifth insulating film 110 is formed, for example, by a CVD method using DCS as a source gas.

[0085] As shown in FIGS. 27A to 27C, in the insulating film processing step, the second insulating film 106 and the fifth insulating film 110 are processed to expose a part of the first insulating film 105 formed under the second insulating film 106 and a part of the third insulating film 107 formed under the fifth insulating film 110. FIG. 27A is a plan view, FIG. 27B is a cross-sectional view taken along line B-B of FIG. 27A, and FIG. 27C is a cross-sectional view taken along line C-C of FIG. 27A. In the insulating film processing step, for example, the second insulating film 106 and the fifth insulating film 110 are processed by dry etching.

[0086] In the insulating film removing step, the first insulating film 105, the third insulating film 107, and the fourth insulating film 109 are removed. In this example, since the first insulating film 105, the third insulating film 107, and the fourth insulating film 109 are formed of SiO, wet etching using HF as a wet etching solution is performed in the insulating film removing step. The inflow openings 102 shown in FIGS. 20A to 20C are formed by the second insulating film 106 and the fifth insulating film 110 remaining after the insulating film removing step. The fluid chip 90 having the inflow openings 102 can make the depth of the groove 108 equal to or less than the minimum processing dimension of the photolithography technique, so that the degree of freedom in designing the inflow openings 102 as the minimum openings is excellent.

[0087] [Fifth Embodiment] In each of the above embodiments, the electrode pair 15 is provided on the upper surface of the analyzers 11 and 41. However, in the fifth embodiment, the electrode pair 15 is provided on the side surface of the analyzer.

[0088] As shown in FIG. 28, a fluid chip 60 is used in the analyzer 120. In the fifth embodiment, the fluid chip 60 is held by a chip frame 124. The chip frame 124 is different from the chip frame 64 of the second embodiment in that it does not have the connection holes 66. The analyzer 120 includes an upper cover sheet 121, an upper flow path sheet 122, a lower flow path sheet 123, and a lower cover sheet 13. Further, the analyzer 120 has a pair of supply portions 14a and 14d and a pair of recovery portions 14b and 14c, similar to the analyzer 41 of the second embodiment.

[0089] The upper cover sheet 121 is different from the upper cover sheet 14 of the second embodiment in that the pair of supply portions 14a and 14d and the pair of recovery portions 14b and 14c are not provided.

[0090] The upper flow path sheet 122 has a pair of supply parts 14a and 14d, a first upper flow path 122a, a second upper flow path 122b, and an opening 122c. The pair of supply parts 14a and 14d are provided on the side surfaces of the upper flow path sheet 122. The supply part 14a is connected to one end of the first upper flow path 122a. The supply part 14d is connected to one end of the second upper flow path 122b. The first upper flow path 122a and the second upper flow path 122b are grooves formed on the surface of the upper flow path sheet 122. The other ends of the first upper flow path 122a and the second upper flow path 122b are connected to each other. The opening 122c is provided at the connection part of the first upper flow path 122a and the second upper flow path 122b, and is connected to the inflow opening 22a of the fluid chip 60.

[0091] The lower flow path sheet 123 has a pair of recovery parts 14b and 14c, a first lower flow path 123a, and a second lower flow path 123b. The pair of recovery parts 14b and 14c are provided on the side surfaces of the lower flow path sheet 123. The recovery part 14b is connected to one end of the first lower flow path 123a. The recovery part 14c is connected to one end of the second lower flow path 123b. The first lower flow path 123a and the second lower flow path 123b are grooves formed on the surface of the lower flow path sheet 123. The other ends of the first lower flow path 123a and the second lower flow path 123b are connected to each other. The connection part of the first lower flow path 123a and the second lower flow path 123b is connected to the in-substrate flow path (not shown) of the fluid chip 60.

[0092] In the analysis device 120, a pair of supply units 14a and 14d and a pair of recovery units 14b and 14c are provided on the same side surface. When filling the upper flow path sheet 122 with the sample liquid, for example, the supply unit 14d is used as a vent hole, and the sample liquid is injected from the supply unit 14a to fill the first upper flow path 122a, the second upper flow path 122b, and the opening 122c with the sample liquid. When filling the lower flow path sheet 123 with the sample liquid, the recovery unit 14c is used as a vent hole, and the sample liquid is injected from the recovery unit 14b to fill the first lower flow path 123a and the second lower flow path 123b with the sample liquid. When performing analysis, for example, an electrode pair 15 (not shown) is provided in the supply unit 14a and the recovery unit 14b, and the supply unit 14d and the recovery unit 14c are blocked by a sealing member or the like (not shown), and the flow of the sample is restricted. Among the pair of supply units 14a and 14d and the pair of recovery units 14b and 14c, it is sufficient that the supply unit 14a and the recovery unit 14b provided with the electrode pair 15 are provided on the same surface, and the positions of the supply unit 14d and the recovery unit 14c not provided with the electrode pair 15 are not particularly limited.

[0093] Note that the analysis device 120 is not limited to using the fluid chip 60, and the fluid chips 10, 40, 70, and 90 may be used. In this case, a supply unit and a recovery unit are provided on the upper flow path sheet 122. Further, on the surface of the upper flow path sheet 122, two systems of grooves, namely, an upper flow path connected to the supply unit and an upper flow path connected to the recovery unit, are formed.

[0094] Instead of providing the pair of supply units 14a and 14d on the side surface of the upper flow path sheet 122, they may be provided on the side surface of the upper cover sheet 121. Instead of providing the pair of recovery units 14b and 14c on the side surface of the lower flow path sheet 123, they may be provided on the side surface of the lower cover sheet 13.

[0095] [Sixth Embodiment] As shown in FIG. 29, for example, in the analysis device 41 shown in FIG. 8, the fluid chip 130 is used instead of the fluid chip 60.

[0096] The fluid chip 130 includes a substrate 131, an upstream flow path 132 as an in-substrate flow path, a front-side insulating film 133, a back-side insulating film 134, an inflow opening 135, and a back opening 136. The substrate 131 is, for example, a silicon substrate with a thickness of 775 μm and a plane orientation of (100). The upstream flow path 132 penetrates the substrate 131 in the thickness direction.

[0097] The front-side insulating film 133 is provided on the surface of the substrate 131. The front-side insulating film 133 is formed of, for example, a SiN film, a SiO film, or the like. In this example, the front-side insulating film 133 is formed of a SiN film. The thickness of the front-side insulating film 133 is, for example, 100 nm.

[0098] The back-side insulating film 134 is provided on the back surface of the substrate 131. The back-side insulating film 134 is formed of, for example, a SiN film, a SiO film, or the like. In this example, the back-side insulating film 134 is formed of a SiN film, similar to the front-side insulating film 133. The thickness of the back-side insulating film 134 is, for example, 100 nm.

[0099] The inflow opening 135 is provided upstream of the upstream flow path 132. The inflow opening 135 is formed in the front-side insulating film 133 and is connected to the upstream flow path 132. The inflow opening 135 allows a sample to flow into the upstream flow path 132. The planar shape of the inflow opening 135 is circular in this embodiment. The diameter of the inflow opening 135 is 200 nm.

[0100] The back opening 136 is provided downstream of the upstream flow path 132. The back opening 136 is formed in the back-side insulating film 134 and is connected to the upstream flow path 132. The back opening 136 allows a sample to flow out from the upstream flow path 132. The planar shape of the back opening 136 is a square with a side length of 200 μm in this embodiment. The diameter of the inscribed circle of this square is defined as the diameter of the back opening 136.

[0101] The upstream flow path 132 is provided inside the substrate 131. The upstream flow path 132 penetrates the substrate 131 in the thickness direction. The upstream flow path 132 has a front surface opening 132a, a back surface opening 132b, a first inner wall 132c, and a second inner wall 132d.

[0102] The front surface opening 132a is provided on the front surface of the substrate 131. The front surface opening 132a is connected to the inflow opening 135. The planar shape of the front surface opening 132a is circular or polygonal. In this embodiment, the planar shape of the front surface opening 132a is a square with a side length of 40 μm. The diameter of the inscribed circle of this square is defined as the diameter of the front surface opening 132a.

[0103] The back surface opening 132b is provided on the back surface of the substrate 131. The back surface opening 132b is connected to the back surface opening 136. The planar shape of the back surface opening 132b is circular or polygonal. In this embodiment, the planar shape of the back surface opening 132b is a square with a side length of 200 μm. The diameter of the inscribed circle of this square is defined as the diameter of the back surface opening 132b.

[0104] The first inner wall 132c is provided between the front surface opening 132a and the back surface opening 132b. The upper end of the first inner wall 132c is connected to the front surface opening 132a. The lower end of the first inner wall 132c is connected to the upper end of the second inner wall 132d, which will be described later. The first inner wall 132c is inclined with respect to the back surface of the substrate 131. The inclination angle of the first inner wall 132c is approximately 55°.

[0105] The second inner wall 132d is provided downstream of the first inner wall 132c between the front surface opening 132a and the back surface opening 132b. The upper end of the second inner wall 132d is connected to the lower end of the first inner wall 132c. The lower end of the second inner wall 132d is connected to the back surface opening 132b. The second inner wall 132d is formed perpendicular to the back surface of the substrate 131.

[0106] Hereinafter, a method for manufacturing the fluid chip 130 will be described with reference to FIGS. 30 to 35. The fluid chip 130 is manufactured by a front surface pattern forming step, a back surface pattern forming step, and a substrate internal flow path forming step.

[0107] As shown in FIG. 30, in the surface pattern forming step, a surface pattern P1 is formed on the insulating film 141 provided on the surface of the substrate 140. The substrate 140 is a silicon substrate. The thickness of the substrate 140 is 775 μm. In the surface pattern forming step, first, insulating films 141 are formed on both surfaces of the substrate 140. The insulating film 141 is formed, for example, by a LP (Low Pressure)-CVD method using DCS as a source gas. Then, a surface pattern P1 in which a portion corresponding to the inflow opening 135 is open is formed on the insulating film 141 provided on the surface of the substrate 140. Since the specific method for forming the surface pattern P1 is the same as that of the above-described embodiments, the description thereof is omitted. In the surface pattern forming step, after the formation of the surface pattern P1, protective films 142 are formed on both surfaces of the substrate 140. The protective film 142 is, for example, a SiO film formed by a CVD method using TEOS as a source gas.

[0108] As shown in FIG. 31, in the back surface pattern forming step, a back surface pattern P2 is formed on the insulating film 141 and the protective film 142 provided on the back surface of the substrate 140. In the back surface pattern forming step, the substrate 140 is inverted, and a back surface pattern P2 is formed at a position corresponding to the surface pattern P1 among the insulating film 141 and the protective film 142 provided on the back surface of the substrate 140. Since the specific method for forming the back surface pattern P2 is the same as that of the above-described embodiments, the description thereof is omitted. In the insulating film 141 and the protective film 142 on which the back surface pattern P2 is formed, a portion corresponding to the back surface opening 136 is open.

[0109] In the substrate internal flow path forming step, an upstream flow path 132 as a substrate internal flow path is formed inside the substrate 140. The substrate internal flow path forming step includes a first etching step, an inner wall protective film forming step, and a second etching step.

[0110] As shown in FIG. 32, in the first etching step, holes 143 are formed by performing dry etching on the back surface of the substrate 140. The holes 143 are formed perpendicular to the back surface of the substrate 140. The side portions of the holes 143 form the second inner wall 132d. The dry etching in the first etching step is performed continuously with the dry etching in the back surface pattern forming step in this example. For this reason, the thickness of the photoresist layer used as a mask in the back surface pattern forming step is set to a thickness considering the depth of the holes 143 formed in the first etching step. In the first etching step, dry etching is performed so as not to penetrate the substrate 140. The remaining film thickness of the substrate 140 excluding the depth of the holes 143 is set based on the size of the bottom of the holes 143 and the size of the bottom of the holes 146 formed in the second etching step described later. For example, when the planar shape of the bottom of the holes 143 is a square with a side length of 200 μm and the planar shape of the bottom of the holes 146 is a square with a side length of 40 μm, the film thickness is set to 120 μm.

[0111] As shown in FIG. 33, in the inner wall protective film forming step, an inner wall protective film 144 is formed inside the holes 143. In the inner wall protective film forming step, first, the inner wall protective film 144 is formed over the entire back surface of the substrate 140. Thereby, the inner wall protective film 144 is formed inside the holes 143, that is, on the bottom and the side portions. The material of the inner wall protective film 144 is not particularly limited as long as it can be selectively removed with respect to the substrate 140 and the insulating film 141. The inner wall protective film 144 is a SiO film in this example. The inner wall protective film 144 may also be a metal film. The method for forming the inner wall protective film 144 is not limited to the CVD method, and a PVD (physical Vapor Deposition) method such as a sputtering method may be used.

[0112] Next, in the inner wall protective film forming step, as shown in FIG. 34, by performing an etch-back of the inner wall protective film 144, portions of the inner wall protective film 144 formed on the back surface of the substrate 140 and portions formed at the bottom of the holes 143 are removed. The inner wall protective film 144 remains on the side portions of the holes 143. When the inner wall protective film 144 at the bottom of the holes 143 is removed, a part of the substrate 140 is exposed from the bottom of the holes 143. Note that the method of forming the inner wall protective film 144 is not limited to the above method. For example, the substrate 140 may be heated in an oxygen atmosphere, the inner wall protective film 144 may be formed on the inner surface of the holes 143 by thermal oxidation of silicon, and the inner wall protective film 144 formed at the bottom of the holes 143 may be removed by etch-back. When the inner wall protective film 144 is formed by thermal oxidation of silicon, it is preferable to make the protective film 142 on the back surface of the substrate 140 thicker in advance in consideration of the amount to be removed by etch-back.

[0113] As shown in FIG. 35, in the second etching process, holes 146 are formed in the substrate 140 by immersing the substrate 140 in a wet etching solution and performing anisotropic wet etching. As the wet etching solution, an alkaline aqueous solution such as KOH (potassium hydroxide) or TMAH (tetramethylammonium hydroxide) is used. The protective films 142 provided on both sides of the substrate 140 and the inner wall protective film 144 provided on the side of the hole 143 function as masks for anisotropic wet etching. Therefore, etching is performed on the portion of the back surface of the substrate 140 that is exposed from the bottom of the hole 143. By anisotropic wet etching, holes 146 are formed in the exposed portion of the substrate 140. The side portion of the hole 146 is inclined with respect to the back surface of the substrate 140 and has an inclination angle of about 55° in this example. The side portion of the hole 146 forms the first inner wall 132c. The second etching process exposes the insulating film 141 provided on the surface of the substrate 140 from the bottom of the hole 146. Since the protective film 142 is formed over the entire surface of the substrate 140, surface damage is suppressed and etching from the surface is prevented during anisotropic wet etching. After the anisotropic wet etching, the protective film 142 and the inner wall protective film 144 are removed by wet etching using, for example, HF as the wet etching solution. Thereby, the fluid chip 130 shown in FIG. 29 is obtained.

[0114] In the fluid chip 130, since the first inner wall 132c is inclined with respect to the back surface of the substrate 131 and the second inner wall 132d is formed perpendicular to the back surface of the substrate 131, the difference between the opening area of the surface opening 132a and the opening area of the back surface opening 132b can be made smaller, so that the fluid chip 130 itself and the analyzer 41 can be miniaturized.

[0115] By making the difference between the opening area of the surface opening 132a and the opening area of the back surface opening 132b of the fluid chip 130 smaller, a plurality of in-substrate flow paths can be provided in one substrate 131, so that a plurality of samples can be analyzed efficiently.

[0116] The fluid chip 130 can adjust the opening area of the surface opening 132a according to the etching amount of dry etching in the first etching process by performing the etching of the substrate 140 by dry etching in the first etching process and anisotropic wet etching in the second etching process, and has excellent design freedom.

[0117] Note that the fluid chip 130 is not limited to one including the front-side insulating film 133 and the back-side insulating film 134. The fluid chip 130 only needs to include at least the front-side insulating film 133.

[0118] [Seventh Embodiment] In the above sixth embodiment, a silicon substrate is used as the substrate 131, but in the seventh embodiment, an SOI (Silicon on Insulator) substrate is used.

[0119] As shown in FIG. 36, the fluid chip 150 includes an SOI substrate 151 as a substrate, an upstream flow path 152 as an in-substrate flow path, a front-side insulating film 133, a back-side insulating film 134, an inflow opening 135, and a back surface opening 136. Since the front-side insulating film 133, the back-side insulating film 134, the inflow opening 135, and the back surface opening 136 are the same as those in the above sixth embodiment, the description thereof is omitted.

[0120] The SOI substrate 151 has a thickness of, for example, 775 μm. The SOI substrate 151 has a base substrate 151a, an insulating layer 151b, and a Si layer 151c. The base substrate 151a is, for example, a single crystal silicon substrate. The thickness of the base substrate 151a is about 670 μm. The insulating layer 151b is provided on the surface of the base substrate 151a. The insulating layer 151b is, for example, a SiO film. The thickness of the insulating layer 151b is about 2 μm. The Si layer 151c is provided on the surface of the insulating layer 151b. The thickness of the Si layer 151c is about 100 μm. The plane orientation of the Si layer 151c is, for example, (100). Note that as the base substrate 151a, a single crystal silicon substrate having the same plane orientation (100) as that of the Si layer 151c, a single crystal silicon substrate having a plane orientation different from that of the Si layer 151c, or a polycrystalline silicon substrate can be used.

[0121] The upstream flow path 152 is provided inside the SOI substrate 151. The upstream flow path 152 penetrates the SOI substrate 151 in the thickness direction. The upstream flow path 152 has a surface opening 152a, a back surface opening 152b, a first inner wall 152c, a second inner wall 152d, and a third inner wall 152e.

[0122] The surface opening 152a is provided on the surface of the SOI substrate 151. The planar shape of the surface opening 152a is circular or polygonal, and in this embodiment, it is a square with a side length of 40 μm.

[0123] The back surface opening 152b is provided on the back surface of the SOI substrate 151. The planar shape of the back surface opening 152b is circular or polygonal, and in this embodiment, it is a square with a side length of 200 μm.

[0124] The first inner wall 152c is provided in the Si layer 151c. The upper end of the first inner wall 152c is connected to the surface opening 152a. The lower end of the first inner wall 152c is connected to the upper end of the third inner wall 152e described later. The first inner wall 152c is inclined with respect to the back surface of the SOI substrate 151. The inclination angle of the first inner wall 152c with respect to the back surface of the SOI substrate 151 is about 55°.

[0125] The second inner wall 152d is provided on the base substrate 151a. That is, the second inner wall 152d is provided downstream of the first inner wall 152c. The upper end of the second inner wall 152d is connected to the lower end of a third inner wall 152e described later. The lower end of the second inner wall 152d is connected to the back surface opening 152b. The second inner wall 152d is formed perpendicular to the back surface of the SOI substrate 151.

[0126] The third inner wall 152e is provided in the insulating layer 151b. That is, the third inner wall 152e is provided between the first inner wall 152c and the second inner wall 152d. The upper end of the third inner wall 152e is connected to the lower end of the first inner wall 152c. The lower end of the third inner wall 152e is connected to the upper end of the second inner wall 152d. The third inner wall 152e is formed substantially perpendicular to the back surface of the SOI substrate 151. The third inner wall 152e is one step lower than the wall surface of the second inner wall 152d.

[0127] Hereinafter, a method for manufacturing the fluid chip 150 will be described with reference to FIGS. 37 to 41. The fluid chip 130 is manufactured by a surface pattern forming step, a back surface pattern forming step, and a substrate internal flow path forming step.

[0128] As shown in FIG. 37, in the surface pattern forming step, a surface pattern P1 is formed on the insulating film 141 provided on the surface of the SOI substrate 153. In the surface pattern forming step, first, the SOI substrate 153 is prepared. The SOI substrate 153 has an insulating layer 153b made of an SiO film and a Si layer 153c formed in this order on the surface of the base substrate 153a. As the base substrate 153a, for example, a single crystal silicon substrate or a polycrystalline silicon substrate is used, and in this example, it is a single crystal silicon substrate. Next, insulating films 154 made of SiN films are formed on both surfaces of the SOI substrate 153. Thereafter, a surface pattern P1 in which a portion corresponding to the inflow opening 135 is open is formed on the insulating film 154 provided on the surface of the SOI substrate 153. Since the specific method of forming the surface pattern P1 is the same as that in each of the above embodiments, the description thereof is omitted. In the surface pattern forming step, after the formation of the surface pattern P1, protective films 155 made of SiO films are formed on both surfaces of the SOI substrate 153.

[0129] As shown in FIG. 38, in the back surface pattern forming step, a back surface pattern P2 is formed on the insulating film 154 and the protective film 155 provided on the back surface of the SOI substrate 153. In the back surface pattern forming step, the SOI substrate 153 is inverted, and the back surface pattern P2 is formed at a position corresponding to the surface pattern P1 in the insulating film 154 and the protective film 155 provided on the back surface of the SOI substrate 153. Since the specific method of forming the back surface pattern P2 is the same as that in each of the above embodiments, the description thereof is omitted. In the insulating film 154 and the protective film 155 on which the back surface pattern P2 is formed, a portion corresponding to the back surface opening 136 is open.

[0130] In the substrate internal flow path forming step, an upstream flow path 152 as a substrate internal flow path is formed inside the SOI substrate 153. The substrate internal flow path forming step includes a first etching step, an inner wall protective film forming step, and a second etching step.

[0131] As shown in FIG. 39, in the first etching step, holes 157 are formed by performing dry etching on the back surface of the SOI substrate 153. The dry etching is performed until it penetrates the base substrate 153a and the insulating layer 153b and reaches the Si layer 153c. That is, in the first etching step, first, the base substrate 153a is dry-etched using the insulating layer 153b as an etching stopper, and then the insulating layer 153b is dry-etched using the Si layer 153c as an etching stopper. The holes 157 are formed perpendicular to the back surface of the SOI substrate 153. Among the side portions of the holes 157, the portion of the base substrate 153a forms the second inner wall 152d, and the portion of the insulating layer 153b forms the third inner wall 152e. The dry etching in the first etching step is performed continuously with the dry etching in the back surface pattern forming step in this example. Therefore, the thickness of the photoresist layer used as a mask in the back surface pattern forming step is set to a thickness considering the depth of the holes 157 formed in the first etching step. The remaining film thickness of the SOI substrate 153 excluding the depth of the holes 157 is set based on the size of the bottom of the holes 157 and the size of the bottom of the holes 159 formed in the second etching step described later.

[0132] As shown in FIG. 40, in the inner wall protective film forming step, an inner wall protective film 158 is formed inside the holes 157. In the inner wall protective film forming step, first, the inner wall protective film 158 is formed over the entire back surface of the SOI substrate 153. Then, by performing an etch-back of the inner wall protective film 158, the inner wall protective film 158 on the back surface of the SOI substrate 153 and the inner wall protective film 158 at the bottom of the holes 157 are removed. The inner wall protective film 158 remains on the side portions of the holes 157. By removing the inner wall protective film 158 at the bottom of the holes 157, a part of the Si layer 153c is exposed from the bottom of the holes 157.

[0133] As shown in FIG. 41, in the second etching process, holes 159 are formed in the SOI substrate 153 by immersing the SOI substrate 153 in a wet etching solution and performing anisotropic wet etching. The protective films 155 provided on both sides of the SOI substrate 153 and the inner wall protective film 158 function as masks for anisotropic wet etching. By anisotropic wet etching, holes 159 are formed in the portion of the Si layer 153c that is exposed from the bottom of the hole 157. The side portions of the holes 159 are inclined with respect to the back surface of the SOI substrate 153 and have an inclination angle of about 55° in this example. The side portions of the holes 159 form the first inner walls 152c. From the bottom of the holes 159, the insulating film 154 provided on the surface of the SOI substrate 153 is exposed. After the anisotropic wet etching, the protective films 155 and the inner wall protective film 158 are removed by wet etching using HF as a wet etching solution, for example. In this example, during wet etching, a part of the insulating layer 153b is removed, and the third inner walls 152e are one step lower than the second inner walls 152d. Thereby, the fluid chip 150 shown in FIG. 36 is obtained.

[0134] In the fluid chip 150, since the first inner walls 152c are inclined with respect to the back surface of the SOI substrate 151, and the second inner walls 152d and the third inner walls 152e are formed perpendicular to the back surface of the SOI substrate 151, the difference between the opening area of the surface opening 152a and the opening area of the back surface opening 152b can be made smaller. Thus, similar to the fluid chip 130, the miniaturization of the fluid chip 150 itself and the miniaturization of the analyzer 41 can be achieved. Further, since a plurality of in-substrate flow paths can be provided in one SOI substrate 151 in the fluid chip 150, a plurality of samples can be efficiently analyzed.

[0135] For the base substrate 153a in which the holes 157 are formed by the dry etching in the first etching process of the fluid chip 150, a single-crystalline silicon substrate or a polycrystalline silicon substrate can be used. When a polycrystalline silicon substrate is used as the base substrate 153a, an inexpensive fluid chip 150 can be obtained.

[0136] In the first etching process, dry etching is performed for etching the base substrate 153a of the SOI substrate 153, and in the second etching process, anisotropic wet etching is performed for etching the Si layer 153c. Therefore, the fluid chip 150 can adjust the opening area of the surface opening 152a by changing the thickness of the Si layer 153c, and thus has excellent design freedom.

[0137] In the first etching process, dry etching of the base substrate 153a is performed using the insulating layer 153b as an etching stopper, so that the opening area of the surface opening 152a can be adjusted more accurately than in the sixth embodiment.

[0138] In the seventh embodiment above, the SOI substrate 151 has been described as an example, but instead of the SOI substrate 151, a structure formed by attaching a thin film silicon substrate on a glass substrate may be used. In this case, in the substrate internal flow path forming process, the inner wall protective film forming process for forming the inner wall protective film 158 can be omitted.

[0139] [Eighth Embodiment] In the sixth embodiment above, the first inner wall 132c is inclined at a specific inclination angle with respect to the back surface of the substrate 131, but in the eighth embodiment, the first inner wall is curved in a concave shape.

[0140] As shown in FIG. 42, the fluid chip 160 includes a substrate 161, an upstream flow path 162 as a substrate internal flow path, a surface-side insulating film 133, a back-side insulating film 134, an inflow opening 135, and a back surface opening 136. The substrate 161 has a base substrate 161a and a SiO film 161b. The base substrate 161a is, for example, a single crystal silicon substrate with a plane orientation of (100). The SiO film 161b is provided on the surface of the base substrate 161a. The thickness of the SiO film 161b is, for example, 2 μm. Note that the base substrate 161a may be a single crystal silicon substrate or a polycrystalline silicon substrate having a plane orientation different from (100).

[0141] The upstream flow path 162 is provided inside the substrate 161. The upstream flow path 162 penetrates the substrate 161 in the thickness direction. The upstream flow path 162 has a front surface opening 162a, a back surface opening 162b, a first inner wall 162c, and a second inner wall 162d.

[0142] The front surface opening 162a is provided on the front surface of the substrate 161. The planar shape of the front surface opening 162a is, for example, a square with a side length of 40 μm. The back surface opening 162b is provided on the back surface of the substrate 161. The planar shape of the back surface opening 162b is a square with a side length of 100 μm.

[0143] The first inner wall 162c is provided on the SiO film 161b. The first inner wall 162c is curved in a concave shape. The upper end of the first inner wall 162c is connected to the front surface opening 162a. The lower end of the first inner wall 162c is connected to the upper end of the second inner wall 162d described later. The lower end of the first inner wall 162c recedes from the opening end of the upper end of the second inner wall 162d.

[0144] The second inner wall 162d is provided on the base substrate 161a. That is, the second inner wall 162d is provided downstream of the first inner wall 162c. The upper end of the second inner wall 162d is connected to the lower end of the first inner wall 162c. The lower end of the second inner wall 162d is connected to the back surface opening 162b. The second inner wall 162d is formed perpendicular to the back surface of the substrate 161. The size of the opening of the second inner wall 162d is substantially the same as that of the back surface opening 162b.

[0145] Hereinafter, the manufacturing method of the fluid chip 160 will be described with reference to FIGS. 43 to 46. The fluid chip 130 is manufactured by a front surface pattern forming step, a back surface pattern forming step, and a substrate internal flow path forming step.

[0146] As shown in FIG. 43, in the surface pattern forming step, a surface pattern P1 is formed on the insulating film 166 provided on the surface of the substrate 165. In the surface pattern forming step, first, the substrate 165 is prepared by forming an SiO film 165b on the surface of the base substrate 165a. As the base substrate 165a, for example, a single crystal silicon substrate or a polycrystalline silicon substrate is used, and in this example, it is a single crystal silicon substrate. The SiO film 167 is formed, for example, by a CVD method using TEOS as a source gas. Then, insulating films 166 are formed on both surfaces of the substrate 165. The insulating film 166 is formed, for example, by an LP-CVD method using DCS as a source gas. Next, a surface pattern P1 in which a portion corresponding to the inflow opening 135 is open is formed on the insulating film 166 provided on the surface of the substrate 165. Since the specific method of forming the surface pattern P1 is the same as that in the above embodiments, the description thereof is omitted. In the surface pattern forming step, after the formation of the surface pattern P1, a protective film 168 is formed on the surface of the substrate 165. The protective film 168 is set to a material and a film thickness that are removed in the time required for etching the SiO film 165b during isotropic wet etching performed in the second etching step described later.

[0147] As shown in FIG. 44, in the back surface pattern forming step, a back surface pattern P2 is formed on the insulating film 166 provided on the back surface of the substrate 165. In the back surface pattern forming step, the substrate 165 is inverted, and a back surface pattern P2 is formed at a position corresponding to the surface pattern P1 in the insulating film 166 provided on the back surface of the substrate 165. Since the specific method of forming the back surface pattern P2 is the same as that in the above embodiments, the description thereof is omitted. In the insulating film 166 on which the back surface pattern P2 is formed, a portion corresponding to the back surface opening 136 is open.

[0148] The substrate internal flow path forming step forms an upstream flow path 162 as a substrate internal flow path inside the substrate 165. The substrate internal flow path forming step includes a first etching step and a second etching step.

[0149] As shown in FIG. 45, the first etching process forms holes 170 by performing dry etching on the back surface of the substrate 165. In the first etching process, dry etching of the base substrate 165a is performed using the SiO film 165b as an etching stopper. The holes 170 are formed perpendicular to the back surface of the substrate 165. The side portions of the holes 170 form the second inner wall 162d. The dry etching in the first etching process is performed continuously with the dry etching in the back surface pattern forming process in this example.

[0150] As shown in FIG. 46, the second etching process forms holes 171 in the SiO film 165b by performing isotropic wet etching on the SiO film 165b. In the second etching process, wet etching using a wet etching solution such as HF is performed. Since the opening on the front surface side of the substrate 165 is blocked by the protective film 168, the wet etching solution flows into the holes 170 from the opening on the back surface side of the substrate 165. By wet etching, holes 171 with side portions curved in a concave shape are formed in the SiO film 165b. In the second etching process, the insulating film 166 provided on the front surface of the substrate 165 is exposed from the bottom of the holes 171. The protective film 168 is also removed in the second etching process. Thereby, the fluid chip 160 shown in FIG. 42 is obtained.

[0151] Similar to the fluid chip 130 of the sixth embodiment, the fluid chip 160 can make the difference between the opening area of the surface opening 162a and the opening area of the back surface opening 162b smaller, so that the fluid chip 160 itself and the analyzer 41 can be miniaturized. Further, since the fluid chip 160 can provide a plurality of in-substrate flow paths in one substrate 161, a plurality of samples can be analyzed efficiently.

[0152] As the base substrate 165a in which the holes 170 are formed by the dry etching in the first etching process, a single-crystalline silicon substrate or a polycrystalline silicon substrate can be used for the fluid chip 160. When a polycrystalline silicon substrate is used as the base substrate 165a, an inexpensive fluid chip 160 can be obtained.

[0153] In the first etching step, since the dry etching of the base substrate 165a is performed using the SiO film 165b as an etching stopper, the opening area of the surface opening 162a can be adjusted more accurately than in the sixth embodiment.

[0154] [Ninth Embodiment] As shown in FIG. 47, the fluid chip 180 includes an epi-substrate 181 as a substrate, an upstream flow path 182 as an in-substrate flow path, a front-side insulating film 133, a back-side insulating film 134, an inflow opening 135, and a back surface opening 136.

[0155] The epi-substrate 181 has a thickness of, for example, 775 μm. The epi-substrate 181 has a base substrate 181a and an epi-layer 181b. The base substrate 181a is, for example, a single crystal silicon substrate doped with P-type impurities. The impurity concentration of the base substrate 181a is 1E19 / cm 3 or more. The epi-layer 181b is provided on the surface of the base substrate 181a. In this example, the epi-layer 181b has a thickness of 100 μm and a volume resistivity of 10 Ω·cm. The impurity concentration of the epi-layer 181b is lower than that of the base substrate 181a. The plane orientation of the epi-layer 181b is, for example, (100). Note that the base substrate 181a may be a single crystal silicon substrate having the same plane orientation (100) as that of the epi-layer 181b, a single crystal silicon substrate having a plane orientation different from that of the epi-layer 181b, or a polycrystalline silicon substrate.

[0156] The upstream flow path 182 is provided inside the epi-substrate 181. The upstream flow path 182 penetrates the epi-substrate 181 in the thickness direction. The upstream flow path 182 has a surface opening 182a, a back surface opening 182b, a first inner wall 182c, and a second inner wall 182d.

[0157] The surface opening 182a is provided on the surface of the epi-substrate 181. The planar shape of the surface opening 182a is circular or polygonal. The back surface opening 182b is provided on the back surface of the epi-substrate 181. The planar shape of the back surface opening 182b is circular or polygonal.

[0158] The first inner wall 182c is provided on the epi-layer 181b. The upper end of the first inner wall 182c is connected to the surface opening 182a. The lower end of the first inner wall 182c is connected to the upper end of the second inner wall 182d. The first inner wall 182c is inclined with respect to the back surface of the epi-substrate 181. The inclination angle of the first inner wall 182c is about 55°.

[0159] The second inner wall 182d is provided on the base substrate 181a. That is, the second inner wall 182d is provided downstream of the first inner wall 182c. The upper end of the second inner wall 182d is connected to the lower end of the first inner wall 182c. The lower end of the second inner wall 182d is connected to the back surface opening 182b. The second inner wall 182d is formed perpendicular to the back surface of the epi-substrate 181.

[0160] Hereinafter, a method for manufacturing the fluid chip 180 will be described with reference to FIGS. 48 to 51. The fluid chip 180 is manufactured by a surface pattern forming step, a back surface pattern forming step, and a substrate internal flow path forming step.

[0161] As shown in FIG. 48, in the surface pattern forming step, a surface pattern P1 is formed on the insulating film 184 provided on the surface of the epi-substrate 183. In the surface pattern forming step, first, the epi-substrate 183 is prepared. The epi-substrate 183 has an epi-layer 183b formed on the surface of the base substrate 183a. As the base substrate 183a, for example, a single crystal silicon substrate or a polycrystalline silicon substrate is used, and in this example, it is a single crystal silicon substrate. Next, an insulating film 184 made of a SiN film is formed on both surfaces of the epi-substrate 183. Thereafter, a surface pattern P1 in which a portion corresponding to the inflow opening 135 is open is formed on the insulating film 184 provided on the surface of the epi-substrate 183. Since the specific method for forming the surface pattern P1 is the same as that in the above-described embodiments, the description thereof is omitted. In the surface pattern forming step, after the formation of the surface pattern P1, a protective film 185 made of a SiO film is formed on the surface of the epi-substrate 183.

[0162] As shown in FIG. 49, in the back surface pattern forming step, a back surface pattern P2 is formed on the insulating film 184 provided on the back surface of the epi-substrate 183. In the back surface pattern forming step, the epi-substrate 183 is inverted, and the back surface pattern P2 is formed at a position corresponding to the front surface pattern P1 in the insulating film 184 provided on the back surface of the epi-substrate 183. Since the specific method of forming the back surface pattern P2 is the same as that in each of the above embodiments, the description thereof is omitted. In the insulating film 184 on which the back surface pattern P2 is formed, a portion corresponding to the back surface opening 136 is opened.

[0163] In the substrate internal flow path forming step, an upstream flow path 182 as a substrate internal flow path is formed inside the epi-substrate 183. The substrate internal flow path forming step includes a first etching step and a second etching step.

[0164] As shown in FIG. 50, in the first etching step, a hole 187 is formed by performing dry etching on the back surface of the epi-substrate 183. The dry etching is performed until it penetrates the base substrate 183a and reaches the epi-layer 183b. In the first etching step, the epi-layer 183b is exposed from the bottom of the hole 187. The hole 187 is formed perpendicular to the back surface of the epi-substrate 183. The side portion of the hole 187 forms a second inner wall 182d. In this example, the dry etching in the first etching step is performed continuously with the dry etching in the back surface pattern forming step.

[0165] As shown in FIG. 51, in the second etching process, the epi-substrate 183 is immersed in a wet etching solution to perform anisotropic wet etching, thereby forming holes 189 in the epi-substrate 183. In the second etching process, a wet etching solution capable of selectively etching the epi-layer 183b having a lower impurity concentration than the base substrate 183a in the epi-substrate 183 is used. As the wet etching solution, an alkaline aqueous solution such as KOH or TMAH is used. By anisotropic wet etching, holes 189 are formed in the portion of the epi-layer 183b that is exposed from the bottom of the hole 187. The side portions of the holes 189 are inclined with respect to the back surface of the epi-substrate 183 and have an inclination angle of about 55° in this example. The side portions of the holes 189 form the first inner wall 182c. The second etching process exposes the insulating film 184 provided on the surface of the epi-substrate 183 from the bottom of the holes 189. After the anisotropic wet etching, the protective film 185 is removed by wet etching using, for example, HF as the wet etching solution. Thereby, the fluid chip 180 shown in FIG. 47 is obtained.

[0166] Similar to the fluid chip 130 of the sixth embodiment, the fluid chip 180 can make the difference between the opening area of the surface opening 182a and the opening area of the back surface opening 182b smaller, so that the fluid chip 180 itself and the analyzer 41 can be miniaturized. Further, since a plurality of in-substrate flow paths can be provided in one epi-substrate 181 in the fluid chip 180, a plurality of samples can be efficiently analyzed.

[0167] As the base substrate 183a in which the holes 187 are formed by the dry etching in the first etching process, a single crystal silicon substrate or a polycrystalline silicon substrate can be used for the fluid chip 180. When a polycrystalline silicon substrate is used as the base substrate 183a, an inexpensive fluid chip 180 can be obtained.

[0168] In the first etching step, dry etching is performed for etching the base substrate 183a of the epi-substrate 183, and in the second etching step, anisotropic wet etching is performed for etching the epi-layer 183b. Therefore, the fluid chip 180 can adjust the opening area of the surface opening 182a by changing the thickness of the epi-layer 183b, and thus has excellent design freedom.

[0169] In the above-described ninth embodiment, the epi-substrate 181 is used, but an SOI substrate may be used instead. As the SOI substrate, a structure having a base substrate with high-concentration impurities, an insulating layer, and a Si layer with low-concentration impurity concentration is used.

[0170] The substrate of the fluid chip can have a structure having a layer or film on which the first inner wall is formed by anisotropic wet etching on a base substrate on which the second inner wall is formed by dry etching. As the material of the base substrate on which the second inner wall is formed and the material of the layer on which the first inner wall is formed, a combination of materials having a difference in etching rate with respect to the wet etching solution in anisotropic wet etching can be used. For example, a combination of N-type silicon doped with impurities by ion implantation and P-type silicon, a combination of N-type silicon doped with impurities during film formation by CVD method and P-type silicon, etc. Also, as the substrate of the fluid chip, a substrate obtained by bonding a silicon substrate and a compound semiconductor substrate may be used.

[0171] [Tenth Embodiment] As shown in FIG. 52, the fluid chip 190 includes a substrate 191, an upstream flow path 192 as an internal flow path in the substrate, a surface-side insulating film 193, a back-side insulating film 194, an inflow opening 195, a back-side opening 196, and a conductive film 197. The substrate 191 is, for example, a silicon substrate with a plane orientation of (100).

[0172] The upstream flow path 192 is provided inside the substrate 191. The upstream flow path 192 penetrates the substrate 191 in the thickness direction. The upstream flow path 192 has a surface opening 192a, a back surface opening 192b, and an inner wall 192c.

[0173] The surface opening 192a opens on the surface of the substrate 191. The surface opening 192a is connected to the inflow opening portion 195. The planar shape of the surface opening 192a is circular or polygonal, etc., and in this embodiment, it is square. The length of one side of the surface opening 192a is, for example, 40 μm.

[0174] The back surface opening 192b opens on the back surface of the substrate 191. The back surface opening 192b is connected to the back surface opening portion 196. The planar shape of the back surface opening 192b is circular or polygonal, etc., and in this embodiment, it is square. The length of one side of the back surface opening 192b is, for example, 1.1 mm.

[0175] The inner wall 192c is provided between the surface opening 192a and the back surface opening 192b. The upper end of the inner wall 192c is connected to the surface opening 192a. The lower end of the inner wall 192c is connected to the back surface opening 192b. The inner wall 192c is inclined with respect to the back surface of the substrate 191. The inclination angle of the inner wall 192c is about 55°.

[0176] The surface-side insulating film 193 is provided on the surface of the substrate 191. The surface-side insulating film 193 is formed of, for example, a SiN film, a SiO film, etc. In this example, the surface-side insulating film 193 is formed of a SiN film. The thickness of the surface-side insulating film 193 is, for example, 20 nm.

[0177] The back surface-side insulating film 194 is provided on the back surface of the substrate 191. The back surface-side insulating film 194 is formed of, for example, a SiN film, a SiO film, etc. In this example, the back surface-side insulating film 194 is formed of a SiN film, similar to the surface-side insulating film 193. The thickness of the back surface-side insulating film 194 is, for example, 20 nm.

[0178] The inflow opening 195 is provided upstream of the upstream flow path 192. The inflow opening 195 is formed in the surface-side insulating film 193 and is connected to the upstream flow path 192. The inflow opening 195 allows a sample to flow into the upstream flow path 192. The inflow opening 195 is the smallest opening in the sample flow path in the analyzer 206 described later. In the present embodiment, the planar shape of the inflow opening 195 is circular. The diameter of the inflow opening 195 is, for example, 200 nm.

[0179] The back surface opening 196 is provided downstream of the upstream flow path 192. The back surface opening 196 is formed in the back surface-side insulating film 194 and is connected to the upstream flow path 192. The back surface opening 196 allows the sample to flow out from the upstream flow path 192. In the present embodiment, the planar shape of the back surface opening 196 is square. The length of one side of the back surface opening 196 is, for example, 1.1 mm.

[0180] The conductive film 197 is provided in contact with the surface-side insulating film 193. The conductive film 197 is provided in contact with at least one of the front and back surfaces of the surface-side insulating film 193, and in the present embodiment, it is provided in contact with the front surface of the surface-side insulating film 193. In the present embodiment, the conductive film 197 is provided over the entire surface of the surface-side insulating film 193, but it may be provided at least in the portion corresponding to the inflow opening 195. The conductive film 197 is formed of a metal, a metal nitride film, or the like. Examples of the metal include titanium, tungsten, platinum, gold, cobalt, nickel, ruthenium, tantalum, and the like. Examples of the metal nitride film include TiN, WN, and the like. The conductive film 197 may be formed of an alloy containing at least one metal selected from the above metals. In the present embodiment, a TiN film is used as the conductive film 197. The thickness of the conductive film 197 is, for example, 30 nm.

[0181] The conductive film 197 has a conductive film opening 198 that connects to the inflow opening 195. The planar shape of the conductive film opening 198 is not particularly limited, and in this embodiment, like the inflow opening 195, it is circular. The diameter of the conductive film opening 198 is set to a value equal to or greater than the diameter of the inflow opening 195. In this embodiment, the diameter of the conductive film opening 198 is 200 nm, the same as that of the inflow opening 195.

[0182] Hereinafter, a method for manufacturing the fluid chip 190 will be described with reference to FIGS. 53 to 56. The fluid chip 190 is manufactured by a conductive film forming step, a surface pattern forming step, a back surface pattern forming step, and a substrate internal flow path forming step.

[0183] As shown in FIG. 53, in the conductive film forming step, after forming the insulating film 201 on both surfaces of the substrate 200, the conductive film 202 is formed on the insulating film 201 on the surface of the substrate 200. The substrate 200 is a silicon substrate. The thickness of the substrate 200 is 775 μm. The insulating film 201 is formed, for example, by a CVD method using DCS as a source gas. The conductive film 202 is formed, for example, by a reactive sputtering method using Ti as a target material and N2 gas as an inert gas. Thereby, the conductive film 202 is provided over the entire surface of the insulating film 201.

[0184] As shown in FIG. 54, in the surface pattern forming step, a surface pattern P1 is formed on the insulating film 201 and the conductive film 202 provided on the surface of the substrate 200. The surface pattern P1 is formed, for example, by forming a photoresist layer (not shown) on the conductive film 202, patterning it by photolithography technology, and dry etching the conductive film 202 and the insulating film 201 on the surface of the substrate 200 in this order using the patterned photoresist layer as a mask. In the insulating film 201 on which the surface pattern P1 is formed, a portion corresponding to the inflow opening 195 is open. In the conductive film 202 on which the surface pattern P1 is formed, a portion corresponding to the conductive film opening 198 is open.

[0185] As shown in FIG. 55, in the back surface pattern forming step, a back surface pattern P2 is formed on the insulating film 201 and the protective film 204 provided on the back surface of the substrate 200. In the back surface pattern forming step, first, a protective film 204 is formed on both surfaces of the substrate 200. The protective film 204 is preferably made of a material having a large etching rate selection ratio with respect to the wet etching solution in the anisotropic wet etching described later. The protective film 32 is, for example, a SiO film formed by a CVD method using TEOS as a source gas. After the formation of the protective film 32, a back surface pattern P2 is formed on the insulating film 201 and the protective film 204 provided on the back surface of the substrate 200. Regarding the formation of the back surface pattern P2, since the same method as the formation of the front surface pattern P1 can be used, the description is omitted. The insulating film 201 and the protective film 204 on which the back surface pattern P2 is formed have an opening at a portion corresponding to the back surface opening 196, exposing a part of the back surface of the substrate 200.

[0186] As shown in FIG. 56, in the substrate internal flow path forming step, an upstream flow path 192 as a substrate internal flow path is formed inside the substrate 200. In the substrate internal flow path forming step, for example, anisotropic wet etching using an alkaline aqueous solution is performed. The protective film 204 functions as a mask for anisotropic wet etching. The wet etching solution in the anisotropic wet etching enters the openings provided in the insulating film 201 and the protective film 204 by the formation of the back surface pattern P2. As a result, a part of the substrate 200 exposed by the insulating film 201 and the protective film 204 on which the back surface pattern P2 is formed is etched. After the substrate internal flow path forming step, the protective film 204 is removed by wet etching using, for example, HF. As a result, the fluid chip 190 shown in FIG. 52 is obtained.

[0187] As described above, in the fluid chip 190, the conductive film 197 is provided in contact with the surface-side insulating film 193. When a sample such as DNA passes through the inflow opening 195 provided in the surface-side insulating film 193, the sample is analyzed by detecting a change in the value of the ionic current. However, when the surface-side insulating film becomes charged, static electricity is generated, and the sample may easily adhere. When the sample adheres to the surface-side insulating film, the number of samples passing through the minimum opening, which has the smallest opening area among the sample flow paths, decreases, and the accurate number of samples cannot be measured, resulting in poor measurement accuracy of the ionic current. Also, when the sample adheres to the minimum opening, the minimum opening is blocked, and the sample cannot be analyzed. In the fluid chip 190, since the conductive film 197 and the surface-side insulating film 193 are in contact, the charging of the surface-side insulating film 193 is suppressed. Therefore, in the fluid chip 190, adhesion of the sample to the surface-side insulating film 193 is prevented, and the measurement accuracy of the ionic current can be maintained well. Also, in the fluid chip 190, it is prevented that the inflow opening 195 is blocked by the sample, and the sample can be analyzed reliably.

[0188] In the fluid chip 190, since the surface-side insulating film 193 is reinforced by the conductive film 197, the thickness of the surface-side insulating film 193 can be reduced. If the thickness of the surface-side insulating film is large, a plurality of samples will enter the inflow opening simultaneously. Therefore, the signal obtained by measuring the ionic current will be a signal based on a plurality of samples, and the measurement accuracy of the ionic current will deteriorate. The thinner the surface-side insulating film, the smaller the number of samples that enter the inflow opening simultaneously. Therefore, the spatial resolution can be improved, and the measurement accuracy of the ionic current can be improved. The fluid chip 190 can achieve a high signal-to-noise ratio (S / N ratio) by thinning the surface-side insulating film 193.

[0189] In the above-described 10th embodiment, the case where the conductive film 202 is continuously formed on the insulating film 201 on the surface of the substrate 200 in the conductive film forming step (see FIG. 53) has been described. However, when the film thickness of the conductive film 197 is sufficiently thin with respect to the diameter of the inflow opening 195, without continuously forming the conductive film 202 on the insulating film 201 on the surface of the substrate 200, after passing through the surface pattern forming step, the back surface pattern forming step, and the substrate internal flow path forming step, and removing the protective film 204 (see FIG. 56), a conductive film may be formed on the insulating film 201 on the surface of the substrate 200. That is, the conductive film forming step may be performed after the substrate internal flow path forming step. In this case, the film thickness of the conductive film is less than 1 / 2 of the diameter of the inflow opening 195. Thereby, when forming the conductive film by the sputtering method or the CVD method, it is possible to prevent the inflow opening 195 from being blocked. When the conductive film forming step is performed after the substrate internal flow path forming step, since a thin conductive film is also formed inside the opening of the insulating film 201, the diameter of the inflow opening 195 can be adjusted by adjusting the film thickness of the conductive film formed on the insulating film 201.

[0190] FIG. 57 is a schematic cross-sectional view showing an analyzer 206 in which the fluid chip 190 is implemented. The analyzer 206 includes, in addition to the fluid chip 190, a lower cover sheet 13, an upper cover sheet 14, an upper flow path sheet 42, a lower flow path sheet 43, a chip frame 64, and the like. The fluid chip 190 is held by the chip frame 64. Although not shown in FIG. 57, the analyzer 206 includes an electrode pair 15 (see FIG. 1), and the electrode pair 15 is provided at a supply portion 14a and a recovery portion 14b provided on the upper cover sheet 14. The analyzer 206 forms a flow path through which a sample passes between the supply portion 14a and the recovery portion 14b. The minimum opening of this flow path is the inflow opening 195 of the fluid chip 190.

[0191] The analysis device 206 further includes a control electrode 208 provided on the conductive film 197 and a voltage application unit 209 that applies a voltage to the control electrode 208. In FIG. 57, the control electrode 208 is formed in a rod shape and is disposed in a through hole (not shown) that penetrates the upper cover sheet 14 and the upper flow path sheet 42. One end of the control electrode 208 is connected to the conductive film 197, and the other end protrudes from the upper surface of the upper cover sheet 14.

[0192] The voltage application unit 209 is electrically connected to the control electrode 208. In this example, the voltage application unit 209 is connected to the other end of the control electrode 208. The voltage application unit 209 controls the potential of the conductive film 197 by applying a voltage of positive or negative polarity to the control electrode 208.

[0193] As described above, since the analysis device 206 includes the control electrode 208 and the voltage application unit 209 and can control the potential of the conductive film 197, even when the surface-side insulating film 193 is charged, the surface-side insulating film 193 can be discharged through the conductive film 197. "Discharging" includes not only that the charged amount of the object to be discharged becomes exactly 0 after discharging, but also that it has decreased compared to before discharging. Therefore, the analysis device 206 can surely prevent the sample from adhering to the surface-side insulating film 193 of the sample.

[0194] The analysis device 206 can more surely prevent the sample from adhering to the surface-side insulating film 193 by changing the polarity of the potential of the conductive film 197 according to the polarity of the sample to be analyzed. For example, when analyzing a sample charged with positive polarity, the analysis device 206 sets the potential of the conductive film 197 to the same positive polarity as the sample, and electrically repels the sample and the surface-side insulating film 193, thereby more surely preventing the sample from adhering to the surface-side insulating film 193 of the sample.

[0195] [11th Embodiment] In the above 10th embodiment, the conductive film 197 is provided on the surface of the surface-side insulating film 193, but in the 11th embodiment, the conductive film is provided on the back surface of the surface-side insulating film.

[0196] As shown in FIG. 58, the fluid chip 210 includes a substrate 191, an upstream flow path 192 as an in-substrate flow path, a surface-side insulating film 193, an inflow opening 195, and a conductive film 211. Note that, unlike the fluid chip 190 of the tenth embodiment, the fluid chip 210 does not include a back-side insulating film 194 and a back opening 196 (see FIG. 52). Since the substrate 191, the upstream flow path 192, the surface-side insulating film 193, and the inflow opening 195 are the same as those of the tenth embodiment, the description thereof is omitted.

[0197] The conductive film 211 is provided in contact with the back surface of the surface-side insulating film 193. That is, the conductive film 211 is disposed between the substrate 191 and the surface-side insulating film 193. The conductive film 211 is the same as the conductive film 197 except for the arrangement. That is, the conductive film 211 is formed of a metal, an alloy, a metal nitride film, or the like.

[0198] The conductive film 211 has a conductive film opening 212 that connects to the inflow opening 195. The planar shape of the conductive film opening 212 is not particularly limited. The diameter of the conductive film opening 212 is set to a value equal to or greater than the diameter of the inflow opening 195. In this embodiment, the conductive film opening 212 has a circular planar shape and a diameter of 200 nm.

[0199] The manufacturing method of the fluid chip 210 is the same as the manufacturing method of the fluid chip 190 except for the conductive film forming step. In the conductive film forming step as the manufacturing method of the fluid chip 210, a conductive film and an insulating film are formed on the surface of the substrate in this order, and no conductive film and insulating film are formed on the back surface of the substrate. The description of the surface pattern forming step, the back surface pattern forming step, and the in-substrate flow path forming step is omitted.

[0200] As described above, in the fluid chip 210, since the conductive film 211 is provided on the back surface of the surface-side insulating film 193 and the conductive film 211 is in contact with the surface-side insulating film 193, the charging of the surface-side insulating film 193 is suppressed. Therefore, similar to the fluid chip 190, the fluid chip 210 can maintain good measurement accuracy of the ionic current and can reliably analyze the sample. In addition, in the fluid chip 210, since the surface-side insulating film 193 is reinforced by the conductive film 211 and the surface-side insulating film 193 can be made thinner, a high S / N ratio can be achieved.

[0201] The fluid chip 210 can be used in the analyzer 206 (see FIG. 57) instead of the fluid chip 190. In the analyzer 206 including the fluid chip 210, for example, the control electrode 208 is disposed on the side surface of the fluid chip 210, and the conductive film 211 of the fluid chip 210 and the control electrode 208 are connected. The control electrode 208 may be provided so as to penetrate the surface-side insulating film 193 and be connected to the conductive film 211. Thereby, the analyzer 206 including the fluid chip 210 can discharge the surface-side insulating film 193 through the conductive film 211, so that the adhesion of the sample to the surface-side insulating film 193 is reliably prevented. In addition, the analyzer 206 including the fluid chip 210 can more reliably prevent the adhesion of the sample to the surface-side insulating film 193 by changing the polarity of the potential of the conductive film 211 according to the polarity of the sample to be analyzed.

[0202] In the above-described Eleventh Embodiment, the conductive film 211 is provided on the back surface of the surface-side insulating film 193, but the conductive film 197 may be further provided on the surface of the surface-side insulating film 193 as in the above-described Tenth Embodiment. That is, the conductive film may be provided on both surfaces of the surface-side insulating film.

[0203] [Twelfth Embodiment] In the above-described Tenth Embodiment, the conductive film 197 is provided over the entire surface of the surface-side insulating film 193, but in the Twelfth Embodiment, the conductive film is provided on a part of the surface-side insulating film.

[0204] As shown in FIG. 59, the fluid chip 220 includes a substrate 191, an upstream flow path 192 as an in-substrate flow path, a surface-side insulating film 193, an inflow opening 195, and a conductive film 221.

[0205] The conductive film 221 is provided in contact with the surface of the surface-side insulating film 193. The conductive film 221 is provided on a part of the surface of the surface-side insulating film 193. More specifically, the conductive film 221 is provided on a portion of the surface of the surface-side insulating film 193 that corresponds to the inflow opening 195. Note that, in the present embodiment, the conductive film 221 is provided on the surface of the surface-side insulating film 193, but it may be provided on the back surface of the surface-side insulating film 193 or on both surfaces of the surface-side insulating film 193. The conductive film 221 is formed of a metal, an alloy, a metal nitride film, or the like.

[0206] In FIG. 59, L1 is the size of the conductive film 221, and L2 is the size of the surface opening 192a of the upstream flow path 192. In the present embodiment, since the planar shapes of the conductive film 221 and the surface opening 192a are square, L1 is the length of one side of the conductive film 221, and L2 is the length of one side of the surface opening 192a. The length L1 of one side of the conductive film 221 is larger than the length L2 of one side of the surface opening 192a of the upstream flow path 192. That is, the size of the conductive film 221 is larger than the surface opening 192a. Note that, for example, when the planar shapes of the conductive film 221 and the surface opening 192a are circular, L1 is the diameter of the conductive film 221, and L2 is the diameter of the surface opening 192a.

[0207] The conductive film 221 has a conductive film opening 222 that connects to the inflow opening 195. The planar shape of the conductive film opening 222 is not particularly limited. The diameter of the conductive film opening 222 is set to a value equal to or greater than the diameter of the inflow opening 195. In the present embodiment, the conductive film opening 222 has a circular planar shape and a diameter of 200 nm.

[0208] The manufacturing method of the fluid chip 220 is the same as that of the fluid chip 190 except for the conductive film forming process. In the conductive film forming process as the manufacturing method of the fluid chip 220, after forming an insulating film and a conductive film on the surface of the substrate in this order, the conductive film is dry-etched into a predetermined shape. The description of the surface pattern forming process, the back surface pattern forming process, and the substrate internal flow path forming process is omitted.

[0209] As described above, since the conductive film 221 and the surface-side insulating film 193 of the fluid chip 220 are in contact with each other, the charging of the surface-side insulating film 193 is suppressed. For this reason, the fluid chip 220 can maintain good measurement accuracy of the ion current and can surely analyze the sample, similarly to the fluid chip 190. Further, in the fluid chip 220, the surface-side insulating film 193 in the region not supported by the substrate 191 by the conductive film 221 is reinforced, and the surface-side insulating film 193 can be thinned, so that a high S / N ratio can be realized.

[0210] The fluid chip 220 can be used in the analyzer 206 (see FIG. 57) instead of the fluid chip 190. Since the analyzer 206 including the fluid chip 220 can discharge the surface-side insulating film 193 through the conductive film 221, the adhesion of the sample to the surface-side insulating film 193 is surely prevented. Further, the analyzer 206 including the fluid chip 220 can more surely prevent the adhesion of the sample to the surface-side insulating film 193 by changing the polarity of the potential of the conductive film 211 according to the polarity of the sample to be analyzed.

[0211] [13th Embodiment] As shown in FIG. 60, the fluid chip 230 includes a substrate 191, an upstream flow path 192 as a substrate internal flow path, a surface-side insulating film 193, an inflow opening 195, and a conductive film 231.

[0212] The conductive film 231 is provided in the upstream flow path 192 as the internal flow path of the substrate. In FIG. 60, the conductive film 231 is provided on the upstream flow path 192 and the back surface of the substrate 191. The conductive film 231 is not provided in the portion of the upstream flow path 192 corresponding to the inflow opening 195. The conductive film 231 is in contact with the back surface of the surface-side insulating film 193 exposed from the surface opening 192a of the upstream flow path 192. The conductive film 231 is formed of metal, alloy, metal nitride film, or the like.

[0213] The conductive film 231 has a conductive film opening 232 connected to the inflow opening 195. The planar shape of the conductive film opening 232 is not particularly limited. The diameter of the conductive film opening 232 is set to a value equal to or greater than the diameter of the inflow opening 195. In the present embodiment, the conductive film opening 232 has a circular planar shape and a diameter of 200 nm.

[0214] The manufacturing method of the fluid chip 230 includes a surface pattern forming step, a back surface pattern forming step, a substrate internal flow path forming step, and a conductive film forming step. In the surface pattern forming step, an insulating film is formed on the surface of the substrate, and a surface pattern is formed on this insulating film. The insulating film on which the surface pattern is formed has an opening in the portion corresponding to the inflow opening 195. In the back surface pattern forming step, a protective film is formed on both surfaces of the substrate, and a back surface pattern is formed on the protective film on the back surface of the substrate. The protective film on the surface of the substrate closes the opening formed in the insulating film. In the substrate internal flow path forming step, an upstream flow path 192 as the internal flow path of the substrate is formed inside the substrate. In the conductive film forming step, first, the protective films provided on both surfaces of the substrate are removed. After removing the protective film, a conductive film is formed in the upstream flow path 192 by a sputtering method. By using a highly directional anisotropic sputtering method, the conductive film is not formed inside the opening of the insulating film, that is, in the portion corresponding to the inflow opening 195. The conductive film is formed on the back surface of the substrate 191, the inclined inner wall 192c of the upstream flow path 192, and the back surface of the insulating film exposed from the surface opening 192a of the upstream flow path 192.

[0215] As described above, since the conductive film 231 and the surface-side insulating film 193 of the fluid chip 230 are in contact with each other, the charging of the surface-side insulating film 193 is suppressed. Therefore, similar to the fluid chip 190, the fluid chip 230 can maintain good measurement accuracy of the ionic current and can reliably analyze the sample. In addition, since the surface-side insulating film 193 is reinforced by the conductive film 231 and the surface-side insulating film 193 can be made thinner in the fluid chip 230, a high S / N ratio can be achieved.

[0216] The fluid chip 230 can be used in the analyzer 206 (see FIG. 57) instead of the fluid chip 190. In the analyzer 206 including the fluid chip 230, for example, the control electrode 208 is disposed on the side surface of the fluid chip 230, and the conductive film 231 of the fluid chip 230 and the control electrode 208 are connected. Since the analyzer 206 including the fluid chip 230 can discharge the surface-side insulating film 193 through the conductive film 231, the adhesion of the sample to the surface-side insulating film 193 is surely prevented. Further, the analyzer 206 including the fluid chip 230 can more surely prevent the adhesion of the sample to the surface-side insulating film 193 by changing the polarity of the potential of the conductive film 231 according to the polarity of the sample to be analyzed.

[0217] [Embodiment 14] The 14th embodiment is obtained by providing the conductive film 197 of the 10th embodiment on the fluid chip 130 of the 6th embodiment.

[0218] As shown in FIG. 61, the fluid chip 240 includes a substrate 131, an upstream flow path 132 as an in-substrate flow path, a surface-side insulating film 133, a back-side insulating film 134, an inflow opening 135, a back opening 136, and a conductive film 197. The upstream flow path 132 has a surface opening 132a, a back opening 132b, a first inner wall 132c, and a second inner wall 132d. The conductive film 197 is provided on the surface of the surface-side insulating film 133 and is in contact with the surface-side insulating film 133. The conductive film opening 198 of the conductive film 197 is connected to the inflow opening 135.

[0219] Since the conductive film 197 and the surface-side insulating film 133 are in contact with each other in the fluid chip 240, the charging of the surface-side insulating film 133 is suppressed. For this reason, the fluid chip 240 can maintain good measurement accuracy of the ion current and can surely analyze the sample. Further, in the fluid chip 240, the surface-side insulating film 133 is reinforced by the conductive film 197, and the surface-side insulating film 133 can be made thinner, so that a high S / N ratio can be realized. Furthermore, the fluid chip 240 can obtain the same operational effects as the fluid chip 130 of the sixth embodiment.

[0220] [Embodiment 15] The fifteenth embodiment is obtained by providing the conductive film 197 of the tenth embodiment on the fluid chip 160 of the eighth embodiment.

[0221] As shown in FIG. 62, the fluid chip 250 includes a substrate 161, an upstream flow path 162 as an in-substrate flow path, a surface-side insulating film 133, a back-side insulating film 134, an inflow opening 135, a back-side opening 136, and a conductive film 197. The substrate 161 has a base substrate 161a and a SiO film 161b. The upstream flow path 162 has a surface opening 162a, a back-side opening 162b, a first inner wall 162c, and a second inner wall 162d. The conductive film 197 is provided on the surface of the surface-side insulating film 133 and is in contact with the surface-side insulating film 133. The conductive film opening 198 of the conductive film 197 is connected to the inflow opening 135.

[0222] Since the conductive film 197 and the surface-side insulating film 133 are in contact with each other in the fluid chip 250, the charging of the surface-side insulating film 133 is suppressed. For this reason, the fluid chip 250 can maintain good measurement accuracy of the ion current and can surely analyze the sample. Further, in the fluid chip 250, the surface-side insulating film 133 is reinforced by the conductive film 197, and the surface-side insulating film 133 can be made thinner, so that a high S / N ratio can be realized. Furthermore, the fluid chip 250 can obtain the same operational effects as the fluid chip 160 of the eighth embodiment.

[0223] The present invention is not limited to the above-described embodiments as they are. In the implementation stage, components can be modified and embodied without departing from the gist thereof. Also, various inventions can be formed by appropriately combining a plurality of components disclosed in the above-described embodiments. For example, a configuration in which some components are deleted from all the components shown in each embodiment is also conceivable. Furthermore, components described in different embodiments may be appropriately combined.

Explanation of Reference Numerals

[0224] 10, 40, 60, 70, 90, 130, 150, 160, 180, 190, 210, 220, 230, 240, 250 fluid chip 11, 41, 120, 206 analyzer 12, 42, 122 upper flow path sheet 12a, 42a, 122a first upper flow path 12b, 42b, 42c, 122b second upper flow path 14a, 14d supply section 14b, 14c recovery section 15 electrode pair 16, 64, 124 chip frame 21, 30, 53, 63, 80, 131, 140, 151, 161, 191 substrate 22, 61, 133, 193 surface-side insulating film 22a, 92a, 102, 135, 195 inflow opening 22b, 92b outflow opening 23, 52, 62, 134, 194 back-side insulating film 23a upstream back-side opening 23b downstream back-side opening 26, 132, 152, 162, 182, 192 upstream flow path 27 downstream flow path 28 back-side flow path 43, 123 lower flow path sheet 44 lower flow path 74 reinforcing film 54, 66 connection hole 123a first lower flow path 123b Second lower flow path 136, 196 Back surface opening 197, 211, 221, 231 Conductive film 198, 212, 222, 232 Conductive film opening

Claims

1. An in-substrate flow channel provided inside a substrate, an insulating film provided on the surface of the substrate, an inflow opening provided in the insulating film for allowing a sample to flow into the in-substrate flow channel, and comprising: the in-substrate flow channel includes a surface opening provided on the surface of the substrate, a back surface opening provided on the back surface of the substrate, a first inner wall provided between the surface opening and the back surface opening and inclined with respect to the back surface of the substrate, a second inner wall provided downstream of the first inner wall between the surface opening and the back surface opening and perpendicular to the back surface of the substrate, and a third inner wall provided between the first inner wall and the second inner wall and perpendicular to the back surface of the substrate; all surfaces constituting the second inner wall are perpendicular to the back surface of the substrate; the substrate is an SOI substrate having a base substrate formed of silicon, an insulating layer provided on the surface of the base substrate, and an Si layer provided on the surface of the insulating layer and formed of silicon; the first inner wall is provided in the Si layer; the second inner wall is provided in the base substrate; the third inner wall is provided in the insulating layer, and is characterized by a fluid chip.

2. The fluid chip according to claim 1, wherein the third inner wall is one step lower than the second inner wall.

3. The fluid chip according to claim 1 or 2, wherein the opening area of the surface opening is smaller than the opening area of the back surface opening.

4. A method for manufacturing the fluid chip according to any one of claims 1 to 3, a surface pattern forming step of forming the insulating film on the surface of the SOI substrate in which the base substrate, the insulating layer, and the Si layer are sequentially formed, and forming a surface pattern having an opening at a portion corresponding to the inflow opening; after the surface pattern forming step, performing dry etching of the base substrate using the insulating layer as an etching stopper, and then performing dry etching of the insulating layer using the Si layer as an etching stopper to form a hole perpendicular to the back surface of the SOI substrate, a first etching step; after the first etching step, an inner wall protective film forming step of forming an inner wall protective film covering the side portion of the hole. After the inner wall protective film forming step, anisotropic wet etching of the Si layer is performed using the inner wall protective film as a mask to form inclined holes inclined with respect to the back surface of the SOI substrate, and then the inner wall protective film is removed, and a second etching step is provided. Among the side portions of the holes, the portion of the base substrate constitutes the second inner wall, the side portions of the inclined holes constitute the first inner wall, and the portion of the insulating layer among the side portions of the holes after the second etching step constitutes the third inner wall. A method for manufacturing a fluid chip, characterized by the above.

Images