WO2012120852A1

WO2012120852A1 - Sensor chip

Info

Publication number: WO2012120852A1
Application number: PCT/JP2012/001436
Authority: WO
Inventors: 健樹山本; 中谷　将也
Original assignee: パナソニック株式会社
Priority date: 2011-03-04
Filing date: 2012-03-02
Publication date: 2012-09-13

Abstract

This sensor chip has a diaphragm, which includes a first surface, and a second surface that faces the first surface, and which has formed therein a plurality of through holes that penetrate the first surface and the second surface. The diaphragm has lower mechanical strength with respect to stress applied from the specific direction, compared with mechanical strength with respect to stress applied from other directions. The through holes have a first through hole and a second through hole that is closest to the first through hole. The direction along a first line segment that connects the center of the first through hole and the center of the second through hole is different from the specific direction.

Description

Sensor chip

The present invention relates to a sensor chip used for a sensor device such as a chemical substance identification sensor or a cell electrophysiological sensor for measuring the electrophysiological activity of a cell.

In recent years, attention has been focused on biosensors and biochips. Biosensors and biochips are used for biosensing proteins, genes, low molecular weight signal molecules, etc. based on the ecological molecular recognition mechanism. Specifically, biosensing can be performed by monitoring a selective specific reaction such as a receptor ligand and an antigen-antibody reaction and a selective catalytic reaction such as an enzyme using a predetermined device.

Conventionally, the patch clamp method is used as an example of a biosensing method. The patch clamp method is one of methods for elucidating the function of ion channels existing in cell membranes or screening (inspecting) drugs using the electrical activity of cells as an index. In the patch clamp method, first, a minute portion (patch) of a cell membrane is gently sucked with a tip portion of a micropipette. Then, a current across the patch is measured at a fixed membrane potential by a microelectrode probe provided on the micropipette. Thereby, the state of opening and closing of one or a small number of ion channels present in the patch is electrically measured. The patch clamp method is one of the few methods that can examine the physiological functions of cells in real time.

However, the patch clamp method requires special techniques and skills for the production and operation of micropipettes. Therefore, it takes a lot of time to measure one sample. Therefore, it is not suitable for use in screening a large amount of drug candidate compounds at high speed. On the other hand, in recent years, a flat-plate microelectrode probe using a microfabrication technique has been developed. Such microelectrode probes are suitable for automated systems that do not require the insertion of a micropipette for individual cells.

Among sensor chips using microfabrication technology, attention is focused on a technique of holding a specimen in a minute through-hole and biosensing the specimen by electrophysiological measurement or measurement using fluorescent molecules.

For example, a cell electrophysiological sensor has been proposed as a method for electrophysiologically measuring an ion channel present in a cell membrane. This does not require the skill of inserting a micropipette into an individual cell like the patch clamp method. Therefore, it is suitable for a high-throughput automated system.

Biological variability (ie, cell state, size, channel expression level) is a major factor in reducing the success rate in planar patch clamp systems. In order to compensate for this decrease in success rate, one type of specimen is always dispensed into several wells for measurement. However, this method has a problem of low throughput.

In order to improve the low throughput, a method for measuring an averaged ion current from a cell population has been proposed. In this method, a sensor device including a plate in which a plurality of through-holes are arranged in a lattice form in each well is used. By measuring using such a sensor device, the ionic current from the cell population is measured. Therefore, the average current measured by this sensor device is uniform between the wells and has little variation. That is, the success rate of measurement with the sensor device is very high. As a result, measurement in a plurality of wells becomes unnecessary, and the throughput is improved.

The following patent documents are listed as prior art documents relating to the invention of this application.

International Publication No. 02/055653 International Publication No. 2007/132769

The sensor chip includes a diaphragm including a first surface and a second surface facing the first surface, and a plurality of through holes penetrating the first surface and the second surface. The diaphragm has a lower mechanical strength against stress from a specific direction than mechanical strength against stress from other directions. The plurality of through holes have a first through hole and a second through hole closest to the first through hole. The direction along the first line segment connecting the center of the first through hole and the center of the second through hole is different from the specific direction.

This makes it possible to improve the durability of the sensor chip in which a plurality of holes are formed in each well, and it is difficult for the sensor chip to break even when stress is applied to the diaphragm at the time of suction and adsorption of the subject.

FIG. 1 is a cross-sectional view of a sensor device according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of the sensor chip in the embodiment of the present invention. FIG. 3 is a cross-sectional view for explaining the method for manufacturing the sensor chip in the embodiment of the present invention. FIG. 4 is a cross-sectional view for explaining the method for manufacturing the sensor chip in the embodiment of the present invention. FIG. 5 is a cross-sectional view for explaining the method for manufacturing the sensor chip in the embodiment of the present invention. FIG. 6 is a cross-sectional view for explaining the method for manufacturing the sensor chip in the embodiment of the present invention. FIG. 7 is a top view of the sensor chip in the embodiment of the present invention. FIG. 8A is a diagram showing a cleavage plane of a silicon (100) substrate. FIG. 8B is a diagram showing a cleavage plane of the silicon (110) substrate. FIG. 8C is a diagram showing a cleavage plane of the silicon (111) substrate.

Hereinafter, the sensor chip 13 and the sensor device using the sensor chip 13 according to the present embodiment will be described with reference to the drawings. However, the present invention is not limited to the following embodiments.

Furthermore, in this embodiment, a cell electrophysiological sensor is used as an example of the sensor device, but the use is not particularly limited as long as the same sensor chip is used.

FIG. 1 is a cross-sectional view of a cell electrophysiological sensor which is an example of a sensor device. A cell electrophysiological sensor 100 as a sensor device has a sensor chip 13 and a mounting substrate 11. The sensor chip 13 has a diaphragm 12 and is mounted on the mounting substrate 11. The cell electrophysiological sensor 100 further includes a first electrode tank 14, a first electrode 15, a second electrode tank 16, and a second electrode 17. The first electrode tank 14 is disposed above the diaphragm 12. The first electrode 15 is disposed inside the first electrode tank 14 and on the upper surface side that is the first surface of the diaphragm 12. The second electrode tank 16 is disposed below the diaphragm 12. The second electrode 17 is disposed inside the second electrode tank 16 and on the lower surface side that is the second surface side of the diaphragm 12. The diaphragm 12 is provided with a plurality of through holes 18 penetrating between the first surface and the second surface.

When using the cell electrophysiological sensor 100, the first electrolyte and the second electrolyte flow in the direction of the arrow shown in FIG. By filling the first electrode tank 14 and the second electrode tank 16 with the electrolytic solution, the diaphragm 12 becomes a boundary surface between the first electrolytic solution and the second electrolytic solution. The subject 19 and the first electrolytic solution are drawn into the through hole 18 by applying pressure from the first surface side of the diaphragm 12 through the through hole 18 or reducing pressure from the second surface side of the diaphragm 12. Then, the subject 19 is sucked and held on the surface of the diaphragm 12 so as to block the through hole 18. As a result, the subject 19 can be sampled.

When mammalian muscle cells are used as the subject 19, it is preferable to use an aqueous solution containing about 155 mM K ⁺ ions, about 12 mM Na ⁺ ions, and about 4.2 mM Cl ⁻ ions as the first electrolyte. Further, it is preferable to use an aqueous solution containing about 4 mM of K ⁺ ions, about 14 mM of Na ⁺ ions, and about 123 mM of Cl ⁻ ions as the second electrolytic solution. Note that the first electrolytic solution and the second electrolytic solution may be different as in the present embodiment, or those having similar components may be used.

Next, by further reducing the pressure from the lower side of the second surface of the diaphragm 12 and sucking, or by introducing a drug such as nystatin, a minute hole communicating with the through hole 18 is formed in the subject 19.

Thereafter, a chemical stimulus or a physical stimulus is given to the subject 19 from above the first surface of the diaphragm 12. Examples of chemical stimuli include chemical stimuli such as chemicals and poisons, and physical stimuli include mechanical displacement, light, heat, electricity, and electromagnetic waves.

Then, when the subject 19 becomes active with respect to these stimuli, for example, the subject 19 releases or absorbs various ions through channels held by the cell membrane. As a result, the potential gradient inside and outside the cell that is the subject 19 changes. This electrical change is detected by the first electrode 15 and the second electrode 17, and the pharmacological reaction of the cells can be examined.

In this case, mammalian muscle cells are used as an example of the subject 19, but the subject 19 is not limited to cells, and may be any object such as particles. For example, a DNA sensor that detects a specific DNA sequence such as a virus or a food production area, a SNP sensor that detects a SNP (single nucleotide polymorphism) sequence, an antigen sensor that detects the presence of an allergen (allergic antigen), It can be widely used in the medical field, the environmental field, and the like.

Note that the first electrode 15 does not necessarily have to be formed in the sensor device, and may be provided so as to be in contact with the solution filled in the first electrode tank 14.

Note that the second electrode 17 does not necessarily have to be formed in the sensor device, and may be provided so as to be in contact with the solution filled in the second electrode tank 16.

FIG. 2 is a cross-sectional view of the sensor chip 13. The sensor chip 13 has a diaphragm 12 and a silicon layer 22. Diaphragm 12 has a first surface and a second surface opposite to the first surface. The silicon layer 22 is bonded to the outer peripheral surface of the first surface of the diaphragm 12. The diaphragm 12 is formed by laminating a silicon layer 20 which is a first layer containing silicon as a main component and a silicon oxide layer 21 which is a second layer containing silicon oxide as a main component. The silicon layer 20 of the diaphragm 12 has a cleavage property in which the mechanical strength with respect to stress from a specific direction is lower than the mechanical strength from other directions. That is, the specific direction is the direction of the cleavage plane of the silicon layer 20. It should be noted that the first surface, the second surface, and the surface of the silicon layer 22 of the diaphragm 12 are layers made of a silicon oxide film 23 that does not have a cleavage property, a crystalline material that has a cleavage property such as a diamond, or the like. Is preferably formed. In the present embodiment, a silicon oxide film 23 is formed on the second surface of the diaphragm 12 and the surface of the silicon layer 22. Here, when a crystalline material having a cleavage property such as diamond is used, it is preferably coated in a direction not parallel to the first or second surface of the diaphragm 12 and the surface direction of the silicon layer 22. That is, it is preferable that the cleavage direction of the crystalline material having cleavage properties is different from the cleavage direction of the silicon layer 22.

The diaphragm 12 is formed with a through hole 18 which is a surface bonded to the silicon layer 22 and communicates from the first surface holding the subject 19 to the second surface which is the opposite surface.

In addition, here, as an example of low mechanical strength against stress from a specific direction, cleavage was shown, but when it has pseudo-cleavage, tearing, cut-off, etc., the density is different in a specific direction. In the case of having a surface, the case where the thickness of the diaphragm is different in a specific direction, the case where many holes and defects are included in the specific direction, and the like are included.

As described above, the silicon layer 20 has a weak cleaving property against a force applied in the direction of a specific surface because the connection between atoms is weak. On the other hand, since the silicon oxide layer 21 does not have a cleavage property, there is no low mechanical strength against stress from a specific direction. Therefore, it is possible to prevent the diaphragm 12 from being cracked by laminating the silicon oxide layer 21 that has cleavage properties and is relatively easy to crack on the silicon layer 20 that does not have cleavage properties.

Note that, as the second layer, the material laminated with the silicon layer 20 may be a material that does not have cleavage property or a material that has a cleavage plane direction different from the cleavage plane direction of silicon. In addition, it is more desirable to use an insulating material having electrical insulating properties because noise during measurement can be reduced. An example of a material that does not have a cleavage property is not limited to silicon oxide, but includes amorphous materials such as silicon nitride, silicon oxynitride, hafnium oxide, aluminum oxide, tantalum oxide, and titanium oxide, and various organic materials. Any material may be mentioned. Moreover, as an example of the material which has cleavage property, crystalline materials, such as a diamond and a mica, are mentioned.

As a material substrate for producing the sensor chip 13, it is desirable to use an SOI (Silicon on Insulator) substrate in which the silicon layer 20 is made of silicon (100). The SOI substrate has a three-layer structure of silicon layer-silicon oxide layer-silicon layer. Unlike the silicon layer, the silicon oxide layer does not have a cleavage property. For this reason, it becomes harder to break than forming a substrate with only a silicon layer.

Although an SOI substrate is used in the present embodiment, the same effect as in the present embodiment can be obtained even if a silicon single crystal plate is used as the substrate. When silicon (100) is used, whether it is an SOI substrate or a silicon single crystal plate, the through holes 18 are formed so that the arrangement thereof does not follow the silicon (110). Yes.

In any case, it is preferable that the entire surface of the sensor chip 13 is covered with the silicon oxide film 23.

Note that silicon (100) includes silicon (010) and silicon (001) that are equivalent due to symmetry of the crystal structure. In addition, silicon doped with elements such as boron and phosphorus is also included.

It is more preferable to use an SOI substrate for the following reason. By using the SOI substrate, a large number of high-precision sensor chips 13 can be manufactured collectively by fine processing by photolithography and etching techniques. In the SOI substrate, the silicon oxide layer serves as an etching stop layer during the etching process in the process of manufacturing the sensor chip 13. Therefore, a highly accurate sensor chip 13 can be manufactured. In addition, since the silicon oxide layer is rich in hydrophilicity, the generation of bubbles during measurement can be suppressed, and the bubbles can be easily removed. Therefore, highly accurate measurement can be realized. If bubbles remain in the vicinity of the through-hole 18 at the time of measurement, the giga-seal property is greatly lowered, and the measurement accuracy is greatly adversely affected. The thickness of the silicon oxide layer in the SOI substrate is preferably 0.5 to 10 μm from the viewpoint of use as an etching stop layer and productivity.

Moreover, the diaphragm 12 may be as thin as several μm depending on the case. Therefore, the silicon layer 22 is formed on the outer peripheral portion of the diaphragm 12 in consideration of handling properties and mounting properties in the manufacturing process. That is, the silicon layer 22 has a function as a holding part of the sensor chip 13, a function of increasing mechanical strength, and a function of storing liquid. However, the silicon layer 22 is not an indispensable requirement, and it is preferable to appropriately select a predetermined dimension depending on the shape and structure of the sensor chip 13. The silicon layer 22 as the holding portion may be formed by etching from the SOI substrate, or a separately formed silicon layer 22 may be bonded to the diaphragm 12. However, it is preferable to form the SOI substrate by etching from the viewpoint of process consistency.

In addition, although the diaphragm 12 becomes harder to break as it is thicker, on the other hand, the time required for processing becomes longer. Thin is desirable from the viewpoint of throughput. In addition, as the diaphragm 12 becomes thicker, the length of the through hole 18 becomes longer. Therefore, the channel resistance when adsorbing the subject 19 with pressure increases, the subject 19 becomes difficult to be sucked, and the success rate of measurement decreases. Therefore, the thickness of the diaphragm 12 is desirably about 5 to 50 μm.

Note that the silicon oxide layer functioning as an etching stop layer is generally formed by thermal oxidation. However, other methods such as a CVD method, a sputtering method, and a CSD method may be used. Instead of a silicon oxide layer, a so-called PSG layer in which silicon oxide is doped with phosphorus, a so-called BSG layer in which silicon oxide is doped with boron, or a BPSG layer in which phosphorus and boron are doped may be used.

In addition, the number and the hole diameter of the through holes 18 are not particularly limited, and may be arbitrarily specified according to the size and shape of the sensor chip 13.

Next, a method for manufacturing the sensor chip 13 will be described with reference to FIGS.

First, an SOI substrate having a silicon layer made of silicon (100) is prepared as a substrate for manufacturing the sensor chip 13.

Thereafter, a first resist mask 24 is formed on the surface of the silicon layer 20 as shown in FIG. At this time, a plurality of mask holes 25 having substantially the same shape as the cross-sections of the desired plurality of through holes 18 are patterned in the first resist mask 24.

Next, as shown in FIG. 4, the silicon layer 20 is etched to form the through holes 18. As an etching method, dry etching capable of high-precision fine processing is desirable. In that case, in order to form the through hole 18 having a high aspect ratio, it is preferable to alternately use an etching gas for promoting etching and a suppressing gas for suppressing etching. In this embodiment mode, SF ₆ is used as an etching gas for promoting etching, and C ₄ F ₈ is used as a gas for suppressing etching. Specifically, plasma is generated by an inductive coupling method of an external coil, and when SF ₆ as an etching gas is introduced therein, F radicals are generated. The F radicals react with the silicon layer 20 and the silicon layer 20 is chemically etched.

At this time, if a high frequency is applied to the silicon layer 20, a negative bias voltage is generated in the silicon layer 20. Then, positive ions (SF ₅ ⁺ ) contained in the etching gas collide vertically toward the silicon layer 20. The silicon layer 20 is physically etched by the impact caused by the collision of ions. In this way, dry etching proceeds in the vertical direction (depth direction) of the silicon layer 20.

On the other hand, when the suppression gas C ₄ F ₈ is used, no high frequency is applied to the silicon layer 20. As a result, no bias voltage is generated in the silicon layer 20. Therefore, CF ⁺ contained in the suppression gas C ₄ F ₈ adheres to the wall surface of the hole formed by dry etching of the silicon layer 20 without receiving a bias in a specific direction. As a result, a uniform fluorocarbon film (not shown) is formed on the wall surface of the hole.

And this fluorocarbon film serves as a protective film to suppress etching. Here, the protective film is formed not only on the wall surface portion of the through-hole 18 formed by etching but also on the bottom surface. However, the protective film formed on the bottom surface is easily removed by the impact of ion collision in etching, as compared with the protective film formed on the wall surface. As a result, only etching in the wall surface direction of the through-hole 18 is suppressed, and etching proceeds only in the vertical direction (depth direction). As the etching proceeds, the through hole 18 eventually reaches the surface of the silicon oxide layer 21. However, the silicon oxide layer 21 has a property that it is difficult to be etched under the above etching conditions. Therefore, etching in the vertical direction (depth direction) stops at the exposed surface of the silicon oxide layer 21. When etching is further continued, etching ions are accumulated on the surface of the exposed silicon oxide layer 21. Then, the etching ions that have entered the through hole 18 and the etching ions accumulated on the surface of the silicon oxide layer 21 are repelled, and the etching ions proceed in the lateral direction. Therefore, in the vicinity of the silicon oxide layer 21, a concave portion 26 that gradually widens in a tapered shape is formed. This is because the diaphragm 12 has a structure in which two kinds of materials of a silicon layer 20 as a conductor and a silicon oxide layer 21 as an insulator are laminated. That is, etching ions are likely to be accumulated on the surface of the insulating layer of the silicon oxide layer 21. Moreover, the etching ions accumulated on the surface of the silicon oxide layer 21 and the etching ions that have entered easily repel. As a result, after the through-hole 18 reaches the silicon oxide layer 21, the etching easily proceeds in the lateral direction (direction parallel to the surface of the silicon oxide layer 21), and the tapered recess 26 is formed. . The depth of the recess 26 is about 1 μm. This depth can be controlled by the etching time.

In addition to SF ₆ , CF ₄ can be used as the etching gas, and CHF ₃ can be used as the suppression gas.

A depression (not shown) may be provided at the end of the through hole 18 on the first surface side or the second surface side. Providing a hollow shape on the first surface side of the diaphragm 12 that holds the subject 19 makes it easier to concentrate the subject 19 in the vicinity of the through hole 18, thereby improving the success rate of measurement.

Next, as shown in FIGS. 5 and 6, the silicon oxide layer 21 is dry-etched. As an etching gas used at this time, for example, a mixed gas of CHF ₃ and Ar is used. In this mixed gas, the plasma-excited Ar gas becomes an etching gas with high straightness. Then, an etching component such as Ar ions that proceeds by sputtering advances straight from the opening of the through hole 18 and enters the through hole 18 to etch only the silicon oxide layer 21 that is an insulator. Further, CHF ₃ hardly forms a polymer film on the surface of the silicon oxide layer 21, but forms a polymer film made of fluorocarbon on the surface of the silicon layer 20. The fluorocarbon film when the through hole 18 is formed also functions as a protective film. Therefore, only the silicon oxide layer 21 can be easily selectively etched.

As a gas used at this time, a mixed gas such as CF ₄ / H ₂ or CHF ₃ / SF ₆ / He may be used.

As described above, the two types of materials of the laminate of the diaphragm 12 have different etching rates for the same gas. Therefore, the silicon oxide layer 21 is not etched when the silicon layer 20 is etched, and the silicon layer 20 is not etched when the silicon oxide layer 21 is etched. Etching utilizing such properties makes it possible to easily form a through hole 18 having a desired shape.

Next, as shown in FIG. 6, a second resist mask 27 is formed on the surface of the silicon layer 22 in the same manner as the first resist mask 24 described above. Thereafter, the cavity 28 is formed by etching the silicon layer 22 under the same conditions as the etching of the silicon layer 20. Also in this case, the progress of etching in the depth direction stops at the exposed surface of the silicon oxide layer 21. As a result, the silicon oxide layer 21 is projected at the peripheral edge of the through hole 18 of the silicon oxide layer 21 (overhang state).

Thereafter, the sensor chip 13 is heated in an atmosphere containing oxygen in a heat treatment furnace in the air. Then, the silicon surface is oxidized, and the silicon oxide film 23 is uniformly formed on the exposed silicon surface. Thereby, the sensor chip 13 as shown in FIG. 2 is completed. The thickness of the silicon oxide film 23 is 200 to 230 nm. At this time, strictly speaking, the thickness of the silicon oxide layer 21 increases simultaneously. However, since oxidation proceeds by oxygen diffusion, the amount of increase differs depending on the thickness of the silicon oxide layer 21 before oxidation. For example, when the thickness of the silicon oxide layer 21 before oxidation is 500 nm, the increase amount is about 50 nm.

FIG. 7 is a top view of the diaphragm 12 of the sensor chip 13. A plurality of through holes 18 are formed in the diaphragm 12. Here, the direction along the line segment L1 connecting the centers of one through hole 18A of the plurality of through holes 18 and the other through hole 18B closest to the through hole 18A is the cleavage plane of the silicon layer 20. Different from the direction (arrow X and arrow Y). That is, the direction along the line connecting the centers of the adjacent through holes 18 that are closest to each other is different from the direction of the cleavage plane of the silicon layer 20. When the subject 19 is aspirated and adsorbed, a large stress is applied between the through hole 18A and the through hole 18B that are closest and adjacent to each other. This stress causes the diaphragm 12 to break. In a silicon substrate, the cleavage plane has a weak force for connecting atoms, and is easily broken by a force from the direction of the cleavage plane. Therefore, the diaphragm 12 is arranged such that the direction along the line segment L1 that connects the centers of the adjacent through

holes

18A and 18B that are closest to each other as in this embodiment is different from the direction of the cleavage plane. Cracking can be effectively prevented.

Here, the meaning of being closest and adjacent to each other means that when attention is paid to an arbitrary through hole 18A among the plurality of through holes 18, the center is located closest to the center of the arbitrary through hole 18A. This means a relationship with the through hole 18B. And the positional relationship in which a through-hole does not exist in the position near the other of the through-hole 18B is represented.

The plurality of through holes 18 may be arranged so that the direction along the line segment connecting the centers of the adjacent through holes 18 that are closest to each other in the plurality of through holes 18 is different from the direction of the cleavage plane of the silicon layer 20. preferable. That is, a plurality of through holes are formed so that the direction along the line connecting the centers of the arbitrary through hole 18 and the other through hole 18B closest to the arbitrary through hole 18A is different from the direction of the cleavage plane of the silicon layer 20. It is preferable to arrange the holes 18. Thereby, the crack of the diaphragm 12 can be prevented more effectively. However, in this case, there may be a case where only some of the through holes 18 do not satisfy the above-mentioned condition due to an error in the manufacturing process or the like.

The diaphragm 12 is preferably formed in a circular shape when viewed from the top. If the shape of the diaphragm 12 is circular, the stress applied to the diaphragm 12 when adsorbing the specimen can be uniformly supported on the outer periphery. On the other hand, if the diaphragm 12 has a non-circular shape such as a square, a corner is formed on the outer periphery of the diaphragm 12, so that the corner is distorted and the diaphragm 12 is cracked. For this reason, cracking of the diaphragm 12 can be prevented by making the shape of the diaphragm 12 circular when viewed from above.

Further, as shown in FIG. 7, the diaphragm 12 or the silicon layer 20 is preferably provided with a mark 30 indicating the direction of the cleavage plane of the silicon layer 20. Thus, when the diaphragm 12 is manufactured, the direction along the line segment connecting the centers of one through hole 18A among the plurality of through holes 18 and the one through hole 18A and the other through hole 18B closest to the through hole 18A is the silicon layer 20. It becomes easy to form the diaphragm 12 so as to be different from the direction of the cleavage plane. Further, since the direction of the cleavage plane can be visually recognized, the direction of the cleavage plane can be recognized during the mounting operation of the sensor chip 13, and the diaphragm 12 can be effectively prevented from cracking during the mounting operation.

The shape of the mark 30 is not particularly limited. However, it is preferable that the shape of the mark 30 has a line segment parallel to the direction of the cleavage plane because the cleavage plane can be easily identified. Further, if the mark 30 has a shape that does not have a point-symmetrical center, the directionality within the wafer can be understood, so that the work can be easily performed. Furthermore, by using different marks 30 for all the sensor chips 13 in the wafer, the position of the sensor chip 13 in the wafer can be tracked, which is advantageous in production management. However, the same effect can be obtained by using several sensor chips 13 as one group without using different marks 30 for all sensor chips 13 and using different marks for each group.

Also, the same effect as that of providing the mark 30 can be obtained by arranging the through hole 18 so that the direction of the cleavage plane can be understood. For example, the direction of the cleavage plane may be determined by making the arrangement of the through holes 18 not point-symmetric with respect to the center of the diaphragm 12.

In the present embodiment, an SOI substrate in which the silicon layer 20 is made of silicon (100) is used. Silicon (100) is a substrate excellent in workability and versatility. In addition to silicon (100), silicon (110) or silicon (111) can be selected for the silicon layer 20. FIG. 8A shows a cleavage plane of a silicon (100) substrate. Similarly, FIG. 8B shows a cleavage plane of the silicon (110) substrate, and FIG. 8C shows a cleavage plane of the silicon (111) substrate.

Even in the case of using silicon (110) and silicon (111), the direction of the line segment connecting the centers of one through hole 18 and the other through hole 18 that are closest and adjacent to each other is different from the direction of the cleavage plane. The above-mentioned effect is acquired by arrange | positioning the through-hole 18 in. However, as shown in FIGS. 8A to 8C, silicon (110) and silicon (111) have more cleaved surfaces and more complicated structures than silicon (100). For this reason, by selecting silicon (100), the direction of the line segment that connects the centers of the adjacent through holes 18 closest to each other is different from the direction of the cleavage plane, rather than selecting silicon (110) and silicon (111). Easy to do. Therefore, using silicon (100) is most effective in terms of preventing cracking.

In the present embodiment, the distance between the centers of the through holes 18 that are closest and adjacent to each other is preferably 20 μm or more from the viewpoint of preventing cracking of the diaphragm 12 and the success rate of measurement. Although depending on the type of specimen and culture conditions, the size of the cell used as the specimen is generally about 20 μm. For this reason, if the distance between the centers of the through holes 18 is smaller than the size of the cells used as the subject, interference between cells occurs, and the success rate of the measurement decreases. Furthermore, when the distance between the centers of the through holes 18 is short, an area that receives stress applied to the diaphragm 12 when the subject is sucked and adsorbed is reduced, and the diaphragm 12 is easily broken.

On the other hand, when the distance between the centers of the through holes 18 is increased, the structurally weak parts are difficult to gather. Therefore, the reliability of the sensor chip 13 is improved. However, when many through-holes 18 are required, the area | region required for formation of the through-hole 18 becomes large. This makes it difficult to reduce the size and cost of the sensor. In the present embodiment, by providing a sufficient distance between the centers of the through holes 18, the durability of the diaphragm 12 is improved and interference between subjects is prevented. Therefore, the center of one through-hole 18 of the plurality of through-holes 18 arranged closest to the center of the diaphragm 12 and the other through-hole 18 closest to the one through-hole 18 is connected. The distance of the line segment is 60 μm.

Further, as shown in FIG. 7, the shape formed by line segments connecting the centers of three adjacent through holes 18 may be arranged in a regular triangle shape. That is, a line segment connecting the centers of one through-hole 18C among the plurality of through-holes 18 and another through-hole 18D that is closest to one through-hole C and another through-hole 18E that is also closest to each other is correct. Arrange them in a triangular shape. Thereby, the several through-hole 18 can be arrange | positioned without waste on the diaphragm 12, and the effect that size reduction and cost reduction of the sensor chip 13 are realizable is acquired. At this time, it is preferable that the direction along the line segment connecting the through holes 18 arranged in a regular triangle shape is different from the direction of the cleavage plane of the silicon layer 20 as described above. Thereby, the crack of the diaphragm 12 can be prevented. However, this is not necessarily the case. In addition, by arranging the through holes 18 in an equilateral triangle shape, the direction of the diaphragm 12 so that the direction along the line connecting the centers of the adjacent through holes 18 that are closest to each other is different from the direction of the cleavage plane of the silicon layer 20. Can be designed and formed easily. Thereby, the diaphragm 12 which is hard to break can be formed.

Further, it is preferable that the plurality of through holes 18 are not arranged near the center P of the diaphragm 12. That is, it is preferable that the plurality of through holes 18 be arranged in a region excluding the vicinity of the center P of the diaphragm 12. Here, the center P of the diaphragm 12 indicates a position where the distance from the outer periphery is equal when the diaphragm 12 is circular as viewed from above, and when the diaphragm 12 is a polygon, the distance from the corner of the outer periphery of the diaphragm 12 is equal. Represents the position. When the subject is aspirated and adsorbed, a particularly large stress is applied to the center P of the diaphragm 12. For this reason, if the through hole 18 is disposed in the vicinity of the center P of the diaphragm 12, a large stress is applied to the through hole 18. Then, a crack from the through hole 18 is likely to occur, and the sensor chip 13 is easily cracked. Thus, by disposing the through hole 18 while avoiding the center P of the diaphragm 12, the diaphragm 12 can be effectively prevented from cracking. Here, the vicinity of the center P of the diaphragm 12 refers to a range of about 50 μm from the center of the diaphragm 12 when the diameter of the diaphragm 12 is about 500 μm.

Further, as shown in FIG. 7, it is preferable to provide a through hole 18 near the outer periphery of the diaphragm 12. Since the sensor chip 13 is held and fixed at the outer peripheral portion, the vicinity of the outer periphery of the sensor chip 13 is the strongest against external stress. For this reason, by providing the through-hole 18 in the vicinity of the outer periphery of the diaphragm 12, the diaphragm 12 is difficult to break and cracking can be effectively prevented. Here, the vicinity of the outer periphery represents a range that is not the center of the diaphragm 12, particularly a range of about 10 μm from the outer periphery.

Further, as described above, the diaphragm 12 is subjected to a greater stress at a position closer to the center. For this reason, from the viewpoint of preventing the diaphragm 12 from cracking, it is preferable that the length of the line connecting the centers of the adjacent through holes 18 that are closest to each other is longer in the vicinity of the center of the diaphragm 12 than in the vicinity of the outer periphery. As the distance from the center of the diaphragm 12 toward the outer periphery decreases, the distance between the centers of the adjacent through holes 18 that are closest to each other is shortened, so that the diaphragm 12 can be prevented from cracking, and a plurality of through holes can be efficiently penetrated on the diaphragm 12. Holes 18 can be arranged. That is, a line segment that connects the centers of an arbitrary through hole 18 and another through hole 18 that is closest to the arbitrary through hole 18 is another line segment that is closest to the other arbitrary through hole 18 and the other arbitrary through hole 18. It is preferable that it is located on the outer peripheral side of the diaphragm 12 and shorter than the line segment connecting the center with the through hole 18. Thereby, the above-described effects can be obtained. For example, as shown in FIG. 7, when the distance between the centers of the adjacent through holes 18 that are closest to each other is L1, L2, and L3 in order from the closest to the center of the diaphragm 12, the distance between the line segments is L1> L2>. L3 is preferable.

Further, it is desirable that the through hole 18 is provided point-symmetrically with respect to the center P of the diaphragm 12. By providing the through hole 18 in this way, a suction force acts at a symmetrical position when the subject 19 is adsorbed when viewed from the entire diaphragm 12. Therefore, it is easy to obtain averaged data. In addition, since stress is applied on the diaphragm 12 on average, the diaphragm 12 can be prevented from cracking.

The shape of the through hole 18 is not particularly limited, and an optimal shape may be selected depending on the type and shape of the subject to be measured. However, in the case of cells or spherical particles, the subject has a shape relatively close to a true sphere. Therefore, it is desirable that the shape of the through hole 18 is close to a perfect circle because the subject can be aspirated isotropically.

It should be noted that even if a part of the plurality of through holes 18 is formed at a position different from the cleaved surface due to some deviation, that is, at a position not on the cleaved surface, it is within the scope of the present embodiment. Moreover, even if it is a case where many of the several through-holes 18 are formed in the position different from a cleaved surface, it is in the range of this Embodiment.

The sensor chip according to the present invention is not easily broken even when the subject is sucked and sucked into the through hole, and has excellent durability. Therefore, it is effective in the medical / biological field where a sensor device with excellent durability is required.

DESCRIPTION OF SYMBOLS 11 Mounting board 12 Diaphragm 13 Sensor chip 14 1st electrode tank 15 1st electrode 16 2nd electrode tank 17 2nd electrode 18 Through-hole 19 Test object 20 Silicon layer 21 Silicon oxide layer 22 Silicon layer 23 Silicon oxide film 24 1st Resist mask 25 Mask hole 26 Recess 27 Second resist mask 28 Cavity 30 Mark L1, L2, L3 Distance between centers of through holes

Claims

A machine having a first surface and a second surface facing the first surface, wherein a plurality of through-holes penetrating the first surface and the second surface are formed. With a diaphragm whose mechanical strength is lower than the mechanical strength against stress from other directions,
The plurality of through holes have a first through hole and a second through hole closest to the first through hole, and the center of the first through hole and the center of the second through hole are A direction along the first line segment to be connected is a sensor chip different from the specific direction.
2. The sensor chip according to claim 1, wherein the diaphragm includes a first layer made of a material having a cleavage property, and the specific direction is a direction of a cleavage surface of the material forming the first layer.
The sensor chip according to claim 2, wherein the cleaving material constituting the first layer includes a silicon single crystal.
The sensor chip according to claim 2, wherein a second layer made of a material having no cleavage property is provided on at least one surface of the first surface and the second surface of the diaphragm. .
At least one surface of the first surface and the second surface of the diaphragm is provided with a second layer made of a material having a cleavage property, and the material constituting the second layer is cleaved. The sensor chip according to claim 2, wherein the direction of the surface is different from the direction of the cleaved surface of the material constituting the first layer.
The diaphragm further includes a third through hole, a fourth through hole and a fifth through hole that are closest to the third through hole, and the third through hole and the fourth through hole. The sensor chip according to claim 1, wherein the fifth through-hole and the fifth through-hole are respectively arranged on vertices of an equilateral triangle.
Direction of a line segment connecting the third through hole and the fourth through hole, direction of a line segment connecting the fourth through hole and the fifth through hole, the fifth through hole and the above The sensor chip according to claim 6, wherein at least one of the directions of line segments connecting to the third through hole is different from the specific direction.
Direction of the line segment connecting the third through hole and the fourth through hole, direction of the line segment connecting the fourth through hole and the fifth through hole, the fifth through hole The sensor chip according to claim 7, wherein all of the direction of the line segment connecting the first through hole and the third through hole are different from the specific direction.
The sensor chip according to claim 1, wherein the plurality of through holes are provided in a region excluding the vicinity of the center of the diaphragm.
The sensor chip according to claim 1, wherein at least one of the plurality of through holes is provided in the vicinity of an outer periphery of the diaphragm.
A line segment connecting the center of any sixth through-hole of the plurality of through-holes and the seventh through-hole closest to the arbitrary sixth through-hole is, of the plurality of through-holes, Claim 1 wherein the diaphragm is located on the outer peripheral side of the diaphragm and shorter than the line segment connecting the centers of the arbitrary eighth through hole and the ninth through hole closest to the optional eighth through hole. The sensor chip described.
The sensor chip according to claim 1, wherein an outer peripheral shape of the diaphragm is circular.
The sensor chip according to claim 1, further comprising a silicon layer provided on an outer periphery of the diaphragm, wherein a mark representing the specific direction is provided on at least one of the diaphragm and the silicon layer.