JP2008114345A - Manufacturing method of regular array body of fine and sharp needle-like structure and its reproduction - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manufacture a regular array body of a sharp needle-like structure having an arbitrary side wall angle by jointly using precise cutting or grinding and an etching technique by a simple means. <P>SOLUTION: An oxide film 21 is formed on a surface of a single crystal silicon substrate 11. A groove 12 having a tapered angle of 10° and a depth of 300 microns is machined by the grinding using a diamond wheel. By further performing grooving for the substrate 11 by rotating the substrate 11 by 90°, the regular array body of a single crystal silicon fine structural body 17 having a distal end flat part 18 is finally obtained. The single crystal silicon fine structural body 17 is etched, and the distal end flat part 18 is etched till the part 18 becomes a sharp distal end part 15. After confirming that the sharp distal end part 15 is formed, the remaining protective fine structural body 22 is removed by hydrofluonic acid solution. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for easily manufacturing a regular array of sharp needle-like structures having an arbitrary side wall taper angle by using a precise cutting or grinding process together with a fine etching technique.

  In the fields of medicine and drug discovery, the development of a fine needle-like structure as a painless needle without pain is in progress. As a method for producing this fine needle-like structure, in particular, as a structure in which the needle-like structure is regularly arranged, an attempt is generally made to form a structure by processing silicon. Silicon is a material that is inexpensive and suitable for microfabrication as used in MEMS devices and semiconductor manufacturing applications. In addition, by applying a semiconductor manufacturing process, it is very easy to manufacture a regular array structure in which a specific pattern is repeatedly arranged.

  As a method of creating a silicon needle structure, an oxide film is formed on both sides of a silicon wafer and patterned, and crystal anisotropic etching is performed on the surface, and dry etching is performed on the back surface. Has been proposed (see, for example, Patent Document 1).

  Similarly, a manufacturing method combining isotropic etching and anisotropic etching has been proposed as a method for creating a silicon needle-like structure (see, for example, Patent Documents 2 and 3).

  By these methods, for example, a needle-like structure having a length of 500 μm or more and a width of 200 μm or less can be created. In addition, the accuracy of blood collection can be increased by regularly arranging the needle-like structures, but according to these methods, a large amount of needle-like structures can be formed on a large-area silicon wafer at a time. Therefore, it is possible to manufacture a large number of regular arrays having a silicon needle structure at a low cost.

In contrast to the manufacturing method using etching, a method of forming a needle-like structure having a polygonal bottom by performing precision machining such as wire cutting in at least two directions has also been proposed (for example, a patent) Reference 4). In this method, as compared with the method of Patent Document 1, there is a problem that the processing speed is significantly reduced as the number of needle-like structures increases. For this reason, it can be said that it is suitable for the method of producing the original for manufacturing replicas, such as resin, rather than using the molded object as it is.
JP 2002-369816 A JP 2002-239014 A JP 2005-199392 A JP-T-2006-513811

  In the method of Patent Document 1 using crystal anisotropic etching, the shape of the needle-like structure to be created depends on the crystal anisotropy of silicon, so that there is a problem that the degree of freedom of the shape is low. In particular, since the sharpness of the tip (needle tip angle) is defined by the angle formed by the crystal plane, a serious problem is that a sufficiently sharp tip cannot always be obtained.

  On the other hand, in the methods of Patent Documents 2 and 3 that combine isotropic etching and anisotropic etching, in principle, a needle-like structure having a somewhat free shape can be manufactured. However, in practice, it is not easy to determine the optimum etching conditions for obtaining a desired angle, and there is a problem that the optimum etching conditions change depending on the height and arrangement density of the needle-like structures.

  Furthermore, when a needle-like structure having a height of, for example, several hundred μm is manufactured by the technique of Patent Documents 1 to 3, a special dry etching apparatus for performing very deep etching is required. As one.

  In contrast to these methods, in the method of Patent Document 4 using wire cutting, a desired shape can be easily processed by setting the operation of the processing apparatus. Although it depends on the processing conditions and the material of the workpiece, it is considered to be superior to the method of Patent Document 1 in terms of the degree of freedom of shape.

  However, as a general drawback of precision machining including wire cutting, the fineness of processing is inferior to the method using etching. In particular, since a sharp tip shape is required in the needle-like structure, a problem that only the tip portion is lost can easily occur.

  The present invention solves the above-mentioned problems by combining precision machining and fine etching technology, and combines the advantages of each processing method, and is a relatively easy and efficient method with a sharp edge having an arbitrary sidewall angle. The object is to produce a regular array of fine needle-like structures.

  In addition, as a precision machining method, cutting or search processing, which can define a machining shape by a machining tool tip shape, is used.

In order to achieve the above object, the present invention provides a method for producing a large number of sharp, fine needle-like protrusions regularly arranged on a base material, comprising a base material having a flat upper surface, By applying groove processing by cutting or grinding to the upper surface of the base material in two directions crossing each other, an upper surface portion in which the flat upper surface portion is left on the upper surface of the base material, and a periphery of the upper surface portion A first side surface having a tapered side surface portion extending to the remaining lower portion excluding the upper portion of the base material, and forming a large number of fine convex portions whose cross section gradually increases from the upper surface portion to the lower portion. Etching the side portions until the sharp tip remains on the upper surface portion, thereby narrowing the convex portion, and a plurality of fine needles regularly arranged on the lower portion and sharpened at the tip A second step of forming a protrusion, and That.
In the present invention, a protective film functioning as an etching mask at the time of etching in the second step is formed in advance on the upper surface of the substrate, and the remaining flat upper surface portion in the first step is formed. In addition, the protective film is left on the upper surface portion, and the protective film remaining on the upper surface is removed after the second step.
Further, the present invention is characterized in that, in the first step, the groove processing is performed in two orthogonal directions.
Further, the present invention is characterized in that, in the first step, the side surface portion is formed in a tapered shape at an angle of 80 °.
Further, the present invention uses the needle-like structure produced by the above-described manufacturing method as a mother mold, creates a concave / convex inverted plate in which the shape of the master mold is transferred, and is regularly arranged on a substrate using the concave / convex inverted plate. In addition, a large number of sharp and fine needle-like protrusions are formed by transfer processing.

That is, in the present invention, as shown in FIG. 1, the taper groove 12 is formed on the base material 11 with a precision cutting or grinding process from at least two directions of X and Y, and has a shape similar to a square weight or the like. A regular array 13 of fine needle-like structures 14 (fine needle-like protrusions) is prepared.

FIG. 2 shows a schematic representation of a part of the acicular structure regular array 13 as viewed from the side. By processing the tapered groove 12 adjacently, a needle-like structure 14 having a sharp tip 15 is formed.

  However, if the sharp tip 15 is formed by the above processing, the tip 16 as shown in FIG. 3 is very likely to occur. This is because the sharp tip 15 is very weak in mechanical strength and easily breaks due to vibration or impact applied during processing.

  In order to solve such problems, parameters such as processing speed are usually optimized and processing is performed in a state where vibration and impact are not applied as much as possible. However, there is a limit to such optimization in a structure such as a needle-like structure where the tip needs to be extremely sharp. Therefore, in the present invention, when performing precise cutting or grinding, the sharp tip portion 15 is formed by adding a separate etching process to avoid forming a sharp structure.

  Specifically, at the completion stage of the above-described processing, as shown in FIG. 4, conditions such as the processing pitch are adjusted so as to form the fine structure 17 (fine convex portion) having the tip flat portion 18. By leaving the tip flat portion 18, the tip 16 can be prevented from being chipped.

  If the tip flat portion 18 is sufficiently small, there is a possibility that it can be used as a painless needle as it is, but generally it is necessary to make the tip sharper. Therefore, the entire substrate 11 is etched so that the entire fine structure 17 having the tip flat portion 18 becomes thin.

  However, if etching is simply performed, the entire fine structure 17 becomes thin, but the tip flat portion 18 remains as it is, and the sharp tip portion 15 cannot be formed. Therefore, the protective microstructure 22 is formed on the tip flat portion 18. The material of the protective microstructure 22 is selected from materials that are resistant to etching.

  Since the protective fine structure 22 functions as a mask during etching, the tip flat portion 18 is prevented from being etched in the depth direction. As a result, etching occurs only in the lateral direction from the tapered surface and in the downward direction from the bottom surface.

  The tip flat portion 18 becomes thinner by etching, and when the amount of etching in the lateral direction becomes substantially equal to ½ of the initial width of the tip flat portion 18, a sharp tip portion 15 is obtained.

  Hereinafter, an embodiment of the present invention will be described with reference to FIG. FIG. 5 (a) shows a cross-sectional shape of the base material 11 to be processed substrate. A substrate 11 having a flat upper surface is prepared. The material of the base material 11 is selected from materials that can be easily processed as described later. Examples thereof include single crystal silicon, a glass substrate, a ceramic substrate typified by alumina, and a resin substrate such as acrylic and polylactic acid.

  Since the surface of the base material 11 is processed on the order of microns, sufficient accuracy is required for the thickness of the base material 11, its in-plane variation, flatness, or surface finishing.

  Next, as shown in FIG. 5B, a thin protective film 21 is formed on the surface of the substrate 11. Since this protective film 21 is finally processed into a protective microstructure 22 and used as an etching mask for the base material 11, the base material 11 and the protective film 21 require materials that can be selectively etched with each other. . Further, the base material 11 and the protective film 21 need to have sufficiently high adhesion so that peeling does not occur during precision machining, and it is necessary to select a combination of materials and a film forming method suitable for this. .

  Next, as shown in FIG. 5C, the tapered groove 12 is repeatedly processed, and the microstructure 17 having the tip flat portion 18 (the upper surface portion where the flat upper surface portion of the base material 11 is left), and A protective microstructure 22 is formed. Here, the fine structure 17 is a tapered shape extending from the upper surface portion where the flat upper surface portion of the base material 11 is left and the remaining lower portion excluding the upper portion of the base material from the periphery of the upper surface portion. The side surface portion is a fine convex portion whose cross section gradually increases from the upper surface portion to the lower portion. The protective fine structure 22 is a portion of the protective film 21 left on the upper surface portion together with the upper surface portion where the flat upper surface portion of the substrate 11 is left. Since FIG. 5C is a cross-sectional view, the taper groove 12 is expressed as processed in only one direction, but in practice, as shown in FIG. Process).

  As a precision machining method for forming the tapered groove 12, a cutting process or a grinding process in which the groove shape can be defined by the shape of the tip of the processing tool is used. By using these processing methods, the operation at the time of processing becomes very simple. It is necessary to determine which processing method is adopted in consideration of the processing characteristics of the substrate 11. For example, when a metal or a resin flat plate is used as the substrate 11, cutting is appropriate, and when glass, ceramics, single crystal silicon, or the like is used, grinding is appropriate. In addition to the processing method, a processing apparatus having a moving mechanism capable of positioning the base material 11 with sufficiently high accuracy for processing a micron-sized structure is required.

  Next, as shown in FIG. 5D, the base material 11 is placed in an etching atmosphere 31, and the whole base material 11 is etched. The important point here is that an etching atmosphere 31 having a selectivity that only the base material 11 is etched and the protective microstructure 22 is not etched is selected. By this selectivity, the tip flat portion 18 is etched only in the lateral direction and becomes thinner.

  As an etching method, wet etching using a reactive solution and dry etching using a reactive gas or plasma are conceivable. In the present invention, these systems are not particularly limited, and any system can be used as long as the selectivity to the base material 11 and the protective microstructure 22 is ensured.

Etching is continued, and as shown in FIG. 5 (e), when the needle-like structure 14 (fine needle-like projections) having the sharp tip 15 is formed, the etching is finished from the etching atmosphere 31 to complete the etching ( Second step). That is, in the second step, only the side surface portion is etched until the sharp tip remains on the upper surface portion, thereby narrowing the convex portion, and a large number of the tips are sharply arranged regularly on the lower portion. Fine needle-like projections are formed.
Thereafter, the remaining protective fine structure 22 is removed by etching to obtain a regular array 13 of needle-like structures 14 shown in FIG. Further, unnecessary portions of the base material 11 are cut and removed, and finally used as a regular array chip 19 having a needle-like structure (FIG. 5 (g)).

  The chip 19 obtained in this way can be used as it is, but it is also possible to manufacture a replica using the regular array 13 before forming a chip as a matrix. By creating a large number of replicas from a single mold, overall manufacturing costs can be greatly reduced and productivity can be increased.

  In addition, by using a biocompatible resin (medical silicone resin, maltose, polylactic acid, dextran, or the like) as a material for the replica, it is possible to reduce the burden on the living body. If replication is assumed, it is possible to use a material with excellent processability as a material of the matrix-shaped regular array 13 even if the biocompatibility is low, thereby facilitating more precise processing.

  A method for producing a duplicate will be described with reference to FIG. First, as shown in FIG. 6A, a metal or wax for transferring the shape is deposited to a sufficient thickness on the regular array 13 serving as a matrix, and the concave / convex inverted plate 41 is created. . After depositing to a desired thickness, the concave / convex inversion plate 41 is peeled off (FIG. 6B).

  Next, as shown in FIG. 6 (c), a duplicate 51 with the projections and recesses reversed is formed again on the projections and depressions plate 41. As a method for forming this replica, a method of melting and pouring a material resin or the like, or pressing a softened material resin or the like can be considered.

  Further, after the replica 51 is peeled off (FIG. 6 (d)), unnecessary portions are cut to obtain a replica 52 in a chip form.

Hereinafter, the present invention will be described more specifically with reference to two examples.
(Example 1)

  FIG. 5 shows an example of manufacturing a regular array of needle-like structures having a height of 300 microns and a side wall angle of 10 ° by precision grinding and plasma etching using a single crystal silicon substrate having a thermal oxide film formed on the surface. Will be described with reference to FIG. In this case, the material of the base material 11 and the protective film 21 is single crystal silicon and thermal oxide film, respectively.

  First, the surface of the single crystal silicon substrate 11 (FIG. 5A) is thermally oxidized to form a dense oxide film 21 on the surface (FIG. 5B). In fact, since a silicon substrate with a thermal oxide film already formed on the surface is also commercially available, it can be used more easily without preparing a large-scale thermal oxidation furnace. The process can be easily advanced.

  Next, the groove 12 having a taper angle of 10 ° and a depth of 300 microns is processed by grinding using a diamond wheel of an outer peripheral blade type. As shown in FIG. 7, the diamond wheel 61 to be used is formed in advance so that both side surfaces of the tip end portion 62 have a tapered shape of 80 °. In addition, it is possible to obtain the taper groove | channel 12 of arbitrary angles by using the wheel which changed the taper angle of the front-end | tip part 62. FIG.

  Using the diamond wheel 61, as shown in FIG. 8, grinding groove processing with a depth of 300 microns is repeated at a pitch that forms the tip flat portion 18. Further, the substrate is rotated by 90 ° to perform groove processing, thereby finally obtaining a regular array of single crystal silicon microstructures 17 having a flat tip 18 (FIG. 5C). When the pitch of the arrangement is desired to be widened while maintaining the shape of the fine structure 17 having the tip flat portion 18, a plurality of grooves are processed so that the tapered grooves 12 are overlapped to obtain a desired groove width. The groove processing may be performed at a pitch that forms the flat tip portion 18.

  Subsequently, the single crystal silicon microstructure 17 is etched by a dry etching apparatus using fluorine plasma until the tip flat portion 18 becomes a sharp tip portion 15 (FIG. 5D). As a method other than plasma etching, dry gas etching using XeF 2 gas or wet etching using hydrofluoric acid / nitric acid mixed aqueous solution may be used.

After confirming that the sharp tip 15 was formed (FIG. 5 (e)), the remaining protective microstructure 22 was removed with an aqueous hydrofluoric acid solution (FIG. 5 (f)). Thereby, the regular array 13 of the acicular structure 14 having the sharp tip 15 is obtained. Finally, unnecessary portions of the regular array 13 are cut and removed to obtain a regular array 19 having a needle-like structure in the form of chips.
(Example 2)

  Next, with reference to FIG. 6, a method for making a nickel concave / convex inverted plate using the silicon regular array obtained in Example 1 and finally making a polylactic acid replica will be described. We will explain by applying the names of various materials.

  First, nickel nickel reversal plate 41 having a shape transferred thereon is manufactured by electroforming metal nickel having a thickness of 500 microns or more on the surface of silicon needle-like regular array 13 obtained in Example 1 (FIG. 6 (a)). )).

  The nickel unevenness inversion plate 41 is peeled off (FIG. 6B), and then polylactic acid is heated and melted and poured into the peeled nickel unevenness inversion plate 41 and then solidified (FIG. 6C). Thus, a polylactic acid replica 51 having a replicated shape is obtained.

  After the polylactic acid replica 51 is peeled off (FIG. 6 (d)), unnecessary portions are cut to obtain a chip 52 of the polylactic acid replica (FIG. 6 (e)).

  As described above, according to the method for manufacturing an ordered array of needle-like structures of the present invention, an ordered array of needle-like structures having an arbitrary side wall angle and a sharp tip can be obtained in a simple process with a high yield. It can be manufactured.

  Since the side wall angle can be obtained in various shapes by changing the tip shape of the processing tool, the degree of freedom of the shape is high. Furthermore, needle-like structures with various taper angles can be manufactured with substantially the same manufacturing method and conditions. Further, even when a regular array having different needle-like structures and different arrangement pitches is manufactured, it can be manufactured by substantially the same manufacturing method.

  Further, by manufacturing a replica using the regular array as a matrix, it is possible to manufacture a regular array having a needle-like structure with a material having a small load on a living body at a low cost. By using a regular array of needle-like structures manufactured according to the present invention as this matrix, it becomes possible to obtain a replica with a sharper tip.

(a) Schematic appearance showing a regular array of needle-like structures manufactured in the present invention, (b) is an enlarged schematic view of a portion where the needle-like structures of FIG. 1 (a) are regularly arranged. is there. It is the schematic which shows the ideal cross-sectional shape of the regular array body of the acicular structure manufactured by precision machining. It is the schematic which shows the failure | damage of the front-end | tip of a needle-like structure which may arise when it manufactures by precision machining. FIG. 4 is a schematic diagram showing a solution according to the present invention for the problem of FIG. It is the schematic explaining the manufacturing process of the regular array body of the acicular structure which concerns on this invention. It is the schematic explaining the manufacturing process of the replica of the regular array body of the acicular structure which concerns on this invention. 1 is a schematic diagram illustrating a diamond wheel used in Example 1. FIG. 3 is a schematic diagram for explaining groove processing in Example 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Base material 12 ... Tapered groove | channel 13 formed in a base material ... The regular array 14 of the acicular structure formed in a base material ... The sharp needle-like structure 15 ... Sharp Tip portion 16 ... Breakage 17 generated at the sharp tip portion ... Pseudo needle-like structure 18 having a flat tip portion ... Chip 21 obtained by cutting an unnecessary portion of the flat tip portion 19 ... 13 ... Protective film 22 ... Protective structure 31 in which 21 is refined by groove processing ... Recessed inversion plate 51 ... 13 copy 52 ... 51 transferred using etching atmosphere 41 ... 13 as a master Chip 61 with diamond cut out ... Diamond wheel 62 ... Diamond wheel tip with 80 ° taper shape

Claims (5)

A method for producing a large number of sharp and fine needle-like protrusions regularly arranged on a substrate,
Prepare a substrate with a flat top surface,
An upper surface portion in which the flat upper surface portion is left on the upper surface of the base material by performing grooving by cutting or grinding in two directions intersecting each other on the upper surface of the base material, and a periphery of the upper surface portion And a taper-shaped side surface portion extending to the remaining lower portion excluding the upper portion of the base material, and forming a plurality of fine convex portions whose cross-section gradually increases from the upper surface portion to the lower portion. And the process of
Etching only the side portion until the sharp tip remains on the upper surface portion to narrow the convex portion,
A second step of forming a large number of fine needle-like protrusions regularly arranged on the lower part and having sharp edges;
A method for producing fine needle-like projections, comprising: On the upper surface of the base material, a protective film that functions as an etching mask at the time of etching in the second step is formed in advance,
In the first step, together with the remaining flat upper surface portion, the protective film is left on the upper surface portion;
After the second step, the protective film remaining on the upper surface is removed.
The method for producing fine needle-like projections according to claim 1. In the first step, the grooving is performed in two orthogonal directions.
The method for producing fine needle-like projections according to claim 1. In the first step, the side surface portion is formed in a tapered shape at an angle of 80 °.
The method for producing fine needle-like projections according to claim 1. The needle-like structure produced by the manufacturing method according to claim 1 is used as a mother mold, and a concavo-convex inverted plate in which the shape of the mother mold is transferred,
A number of sharp and fine needle-like protrusions regularly arranged on a substrate using the concavo-convex inverted version are transferred and molded.
A method for producing a needle-like structure.

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