JP2005198865A - Silicone needle and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a silicone needle having good productivity, a large aspect ratio and excellent needling performance in which a high-density arrangement of a group of needles is achieved (in other words, a group of needles in high density is formed), and also to provide a method for producing the same. <P>SOLUTION: The silicone needle of the invention comprises a plurality of needles formed on a substrate. Each of the plurality of needles has a needle body whose outer diameter is tapered continuously toward its leading edge. The method for producing the silicone needle is as follows: anisotropic etching is conducted after a mask is applied on the substrate; deposited layers on the sides are removed; and isotropic etching is further conducted. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a silicon needle used as a fine needle used in, for example, medical treatment, biological phenomenon, and drug discovery, and a method for manufacturing the same.

  Attempts have been made to use silicon needles (usually composed of a plurality of needle groups) produced by etching a silicon wafer as fine needles used in medicine, biological phenomena, and drug discovery. In the plurality of silicon needles, each needle has a desired taper angle and a pointed tip.

  As a conventional silicon needle, for example, the one shown in FIG. 4 exists. The silicon needle of the form shown in FIG. 4 is formed by performing isotropic etching on a silicon wafer, for example, and has a gentle taper shape from the base end portion 102 to the tip end portion 101 as a whole. ing.

The etching performed when forming such a silicon needle 100 is isotropic wet etching in which a silicon wafer is etched using HNO ₃ / HF / CH ₃ COOH / H ₂ O as a solution, or SF _6. A preferable example is dry etching in which etching is performed by plasma generated by introducing a mixed gas such as / O ₂ . Based on such a method, a structure having a taper shape as a whole is formed from the base end portion 102 to the tip end portion 101 as shown in FIG.

  However, in such a conventional method of manufacturing a silicon needle, it is extremely difficult to manufacture a needle having an aspect ratio of 1 or more, which is the ratio of the diameter of the end of the silicon needle to the height of the silicon needle. For this reason, not only silicon needles cannot be formed at a high density, but also inconvenience that it becomes difficult to satisfy the required individual needle specifications can occur.

  Another type of silicon needle is proposed in Japanese Patent Application Laid-Open No. 2002-239014. As shown in FIG. 5, the gazette includes a tip 201 having a tapered shape with a diameter reduced toward the tip, and a base end 202 that is continuous with the tip 201 and is a cylinder having the same diameter in the thickness direction. A silicon needle 200 is disclosed.

  However, this proposed needle shape has a disadvantage that the puncture resistance is increased because the shoulder 222 exists at the boundary between the distal end portion 201 and the proximal end portion 202.

JP 2002-239014 A

  The present invention was devised under such circumstances, and its purpose is to provide excellent productivity, a high aspect ratio and a high needle group arrangement density (that is, a needle group at a high density). It is an object of the present invention to provide a silicon needle excellent in puncture properties and a method for manufacturing the same.

In order to solve such a problem, the present invention is a silicon needle provided with a plurality of needle-like bodies standing and integrally formed on a base, wherein the unit square of the plurality of needle-like bodies is provided. The arrangement density per millimeter is 20 to 70 / mm ² , and the plurality of needle-like bodies are configured to include a needle body having an outer diameter that gradually decreases gradually toward the tip. .

As a preferred embodiment of the present invention, the height of the plurality of needle-like bodies is H, the outer diameter at the position 1 / 3H from the tip is D ₁ , and the outer diameter at the position 2 / 3H from the tip. the If as D _2, the value of D ₁ / D ₂ ratio is configured to be in the range of 0.4 or more and less than 1.0.

  Moreover, as a preferable aspect of the present invention, a height H of the plurality of needle-like bodies is configured to be 60 to 200 μm.

  The present invention also relates to a method for manufacturing a silicon needle comprising a plurality of needle-like bodies integrally formed on a substrate by etching a silicon wafer, wherein the method forms a plurality of needle-like bodies. A process of providing a mask corresponding to the location to be formed, and an etching step and a deposition step are repeated on the silicon wafer with the mask provided to form a deposition layer on the side surface serving as the basis of the needle-shaped body. A first etching step for performing anisotropic etching having selective etching property in a thickness (thickness) direction, a step for removing a deposited layer deposited on the side surface portion, and isotropic etching for the silicon wafer. And a second etching step to be applied.

  As a preferred embodiment of the manufacturing method of the present invention, the mask is formed of a circular group formed by photolithography or etching after the silicon wafer surface is oxidized or a silicon nitride film is formed on the silicon wafer. Configured as a mask pattern.

Moreover, as a preferable aspect of the manufacturing method of the present invention, the arrangement density of the mask pattern is configured to be 20 to 70 / mm ² .

  The silicon needle of the present invention includes a plurality of needle-like bodies formed on a base body, and the plurality of needle-like bodies have an outer diameter that gradually decreases gradually toward the tip. The silicon needle manufacturing method of the present invention is provided with a main body, and after providing a mask, performing isotropic etching, then removing the deposited layer deposited on the side surface, and further isotropic Since it is configured to be etched, the productivity is good, the aspect ratio is large, and the arrangement density of the needle group can be increased (that is, the needle group can be formed at a high density), which makes it extremely puncturable. An excellent silicon needle can be obtained.

  Hereinafter, the silicon needle of the present invention and the manufacturing method thereof will be described in detail with reference to FIGS.

  FIG. 1 is a schematic perspective view showing a part of a silicon needle of the present invention provided with a plurality of needle-like bodies formed on a substrate as a result of etching, and FIG. 2 is a schematic view focusing on one needle-like body. FIG. 3A to FIG. 3D are schematic cross-sectional views for explaining the silicon needle manufacturing method of the present invention over time.

  As shown in FIG. 1, the silicon needle 1 of the present invention includes a plurality of needle-like bodies 10 integrally formed on a substrate 2 (material is silicon) obtained by etching a silicon wafer.

The needle-like bodies 10 are formed standing on the base 2, and the arrangement density per unit square millimeter of the plurality of needle-like bodies 10 is 20 to 70 pieces / mm ² . If the arrangement density is too large, the outer diameter of the needle itself must be reduced to the limit, which causes problems such as the breakage of the needle-like body. In addition, there is inevitably an upper limit due to manufacturing limitations at the current technical level.

  As shown in the figure, each of the plurality of needle-like bodies 10 according to the present invention includes a needle body 18 having an outer diameter that gradually decreases toward the tip. As can be easily understood from the manufacturing method described later, the needle body 18 is formed by gradually forming a substantially cylindrical body formed by anisotropic etching into a needle shape by isotropic etching. It has a gentle continuous straight line or curved shape from the base to the base.

  Thus, the puncture resistance in the entire area of the needle body 18 is finished to a level that does not hinder puncture at all.

As shown in FIG. 2, the plurality of needle-like bodies 10 according to the present invention has a height H, an outer diameter at a position 1 / 3H from the tip, D ₁ , and a position at 2 / 3H from the tip. When the outer diameter is D ₂ , the D ₁ / D ₂ ratio value is in the range of 0.4 or more and less than 1.0. When this value is less than 0.4, there is a disadvantage that the aspect ratio is lowered due to the needle pitch, and when this value is 1.0 or more, the needle shape becomes a reverse taper so that the needle shape is easily broken.

  The height H of the plurality of needle-like bodies 10 is 60 to 200 μm, more preferably about 150 to 200 μm, and the silicon needle 1 of the present application effectively functions as a fine needle used for medical treatment, biological phenomenon, and drug discovery. The required length for is required.

  Next, a method for manufacturing the silicon needle 1 of the present invention will be described with reference to FIG.

  The silicon needle manufacturing method of the present invention is formed by etching a silicon wafer in a predetermined step, and is formed so that a plurality of needle-like bodies are erected integrally on a base. Hereinafter, it demonstrates in order of a process.

(1) Step of providing a mask so as to correspond to the locations where a plurality of needle-like bodies are to be formed As shown in FIG. 3A, the mask 22 is provided so as to correspond to the locations where a plurality of needle-like bodies are to be formed. Provided. In the example of FIG. 3A, the situation where two needle-like bodies are formed is partially shown. In the illustrated example, a photoresist 23 for pattern formation exists on the mask 22.

The mask 22 is formed by oxidizing the surface of the silicon wafer 31 to form an oxide film (for example, SiO ₂ ) and / or a silicon nitride film on the silicon wafer 31, and then applying a photoresist and performing photolithography. A mask pattern is formed. Further, when the thickness of the silicon oxide film is 1.5 μm or more, the mask for forming the needle may be only the silicon oxide film.

  Normally, the masks 22 are all patterns having the same diameter, and the size can be exemplified by, for example, a diameter of about 20 to 80 μm.

(2) First Etching Step for Performing Anisotropic Etching Next, a first etching step for performing anisotropic etching is performed as shown in FIG. This process is performed in order to form the cylindrical body 35 that is the basis of the needle-like body by repeating the etching step and the deposition step on the silicon wafer 31 with the mask 22 provided. That is, the cylindrical body 35 is formed and anisotropic etching having selective etching properties in the height (thickness) direction is performed while forming the deposition layer 34 on the side surface.

  When performing anisotropic etching, for example, it is preferable to use an ICP-RIE (reactive ion etching by inductively coupled plasma) apparatus.

Using this ICP-RIE apparatus, a so-called Bosch process is performed in which, for example, an etching gas of SF ₆ and a deposition gas of C ₄ F ₈ , for example, are alternately converted into plasma as a reaction gas and the etching step and the deposition step are repeated.

  By such a first etching step, as shown in FIG. 3B, for example, a cylindrical body 35 having a height of about 130 to 170 μm, which is the basis of the needle-like body, is formed as an etching remaining shape.

  The flow rate of the reaction gas introduced into the apparatus in the etching step is about 100 to 200 sccm, the processing time per time is about 5 to 15 seconds, the gas pressure is about 4.0 to 4.7 Pa, and the power applied to the coil Is about 600 to 900 W, and the power applied to the substrate electrode is about 15 to 25 W.

  The flow rate of the reaction gas introduced into the apparatus in the deposition step is about 50 to 80 sccm, the processing time per time is about 5 to 10 seconds, the gas pressure is about 1.3 to 2.0 Pa, and the power applied to the coil Is about 600 to 900 W.

(3) Step of removing the deposited layer deposited on the side surface serving as the basis of the needle-like body After performing such an anisotropic etching step, it becomes the basis of the needle-like body as shown in FIG. A step of removing the deposited layer 34 (FIG. 3B) deposited on the side surface is performed. As the solution for removal, a mixed solution of H ₂ SO ₄ / H ₂ O ₂ / H ₂ O is preferably used. The mixing volume ratio of H ₂ SO ₄ / H ₂ O ₂ / H ₂ O is about 3 to 9: 3: 1, and the processing time is about 10 to 30 minutes. The solution may not normally be stirred. Moreover, it is good to perform the rinse with a pure water for about 10 to 30 minutes after a process. In this step, the photoresist 23 is also usually removed as shown in FIG.

(4) Third etching step for performing isotropic etching After removing the deposited layer, isotropic etching is then performed as a second etching step to form the needle shape shown in FIG. 3 (d). Processing is done. By this etching step, a silicon needle-like body 10 having a tapered needle body 18 that is tapered toward the tip as shown in FIG. 3D is formed.

  The needle-like body 10 made of silicon usually has a gentle needle-like side-curved shape and is finished in a form that does not hinder puncture at all.

  The isotropic etching process is performed on the silicon wafer 31 with the mask 22 provided. As the isotropic etching, either wet etching or dry etching may be used.

When performing isotropic dry etching, for example, the above-described ICP-RIE apparatus is preferably used. For example, SF ₆ is suitably used as the etching reaction gas for the silicon wafer 31. The flow rate of the reaction gas introduced into the apparatus is about 100 to 150 sccm, the gas pressure is about 4.0 to 5.1 Pa, the applied power to the coil is about 600 to 900 W, and the applied power to the substrate electrode is 3 to 10 W. It is said to be about.

When performing an isotropic wet etching, suitable etching solution _can be exemplified _{HNO 3 / HF / CH 3 COOH} / H 2 O. The mixing volume ratio of HNO ₃ / HF / CH ₃ COOH / H ₂ O is about 6 to 250: 40 to 760: 0 to 200: 42 to 1350, and the processing time is about 15 to 525 seconds.

  In particular, isotropic wet etching using the latter solution is advantageous because the mask 22 that can be dropped by etching can be moved out of the dropping position to a place that does not affect the product.

  Moreover, it is good to perform the rinse with a pure water for about 5 to 30 minutes after a process.

The present invention will be described in further detail with reference to specific examples.
(Example 1)
A silicon wafer 31 having a thickness of 600 μm was prepared. Next, after the surface of the substrate of the silicon wafer 31 is thermally oxidized to form a silicon oxide layer, the mask 22 is formed so as to correspond to locations where a plurality of needle-like bodies are to be formed using a photoresist method and an etching method. (Reference numeral 23 is a photoresist) (FIG. 3A). The diameter of the mask 22 (reference numeral 23) was 50 μm. The target density of a plurality of needle-like bodies per unit square millimeter was set to 48 / mm ² .

  Next, a first etching process for performing anisotropic etching on the silicon wafer 31 was performed in the following manner. That is, the anisotropic etching having selective etching property in the height (thickness) direction while forming the deposition layer 34 on the side surface which is the basis of the needle-like body by repeating the etching step and the deposition step on the silicon wafer 31. As shown in FIG. 3B, a hole having a depth of about 150 μm was formed, and a cylindrical body 35 serving as a base of the needle-like body was formed as an etching remaining shape.

The etching step and the deposition step were repeated by using the ICP-RIE apparatus for the first etching treatment process, by making the etching gas of SF ₆ and the deposition gas of C ₄ F ₈ alternately into plasma as the reaction gas.

The flow rate ratio of SF ₆ reactive gas and C ₄ F ₈ reactive gas introduced into the apparatus in the etching and deposition steps is SF ₆ / C ₄ F ₈ = 8/3, and the ratio of processing time per time is etching / deposition = The gas pressure ratio was 3/2, the etching / deposition was 3, the power applied to the coil was 900 W, and the power applied to the substrate electrode was 18 W.

  The etching step and the deposition step were alternately repeated to perform anisotropic etching for a total of 70 minutes.

After performing such an anisotropic etching step, as shown in FIG. 3C, the deposited layer 34 (FIG. 3B) deposited on the side surface serving as the basis of the needle-like body is converted into H ₂ SO ₄ / It was removed using a H ₂ O ₂ / H ₂ O mixed solution. The mixed volume ratio of H ₂ SO ₄ / H ₂ O ₂ / H ₂ O used was 5/3/2, and the treatment time was 15 minutes. After the treatment, rinsing with pure water was performed for 15 minutes.

  Next, as shown in FIG. 3D, an isotropic etching process as a second etching process was performed.

Second etching treatment condition Isotropic etching in the second etching step is performed using HNO ₃ / HF / CH ₃ COOH / H ₂ O (mixing volume ratio = 25/637/40/298) as a treatment liquid. The time was 1 minute 15 seconds. The solution was not stirred. Further, after treatment, rinsing with pure water was performed for 10 minutes.

  Thus, as shown in FIG. 3 (d), the silicon needle-like body 10 provided with the needle body 18 having a tapered shape continuously reduced in diameter toward the tip was formed.

The height H of the plurality of needle-like bodies is 135 μm, the outer diameter D ₁ at the position 1 / 3H from the tip is 19 μm, and the outer diameter D ₂ at the position 2 / 3H from the tip is 31 μm. Yes, the value of D ₁ / D ₂ ratio was 0.61. It was confirmed that the side surface of the needle body 18 was gently curved and finished to a level that did not hinder puncture at all.

  For example, it is used as a fine needle for use in medicine, biological phenomena, and drug discovery.

FIG. 1 is a schematic perspective view showing a part of a silicon needle of the present invention having a plurality of needle-like bodies formed on a substrate. FIG. 2 is a schematic side view focusing on one acicular body. 3 (a) to 3 (d) are schematic cross-sectional views for explaining the silicon needle manufacturing method of the present invention over time. FIG. 4 is a schematic perspective view showing a part of a conventional silicon needle having a plurality of needle-like bodies formed on a base body as a conventional example. FIG. 5 is a schematic perspective view showing a part of a conventional silicon needle having a plurality of needle-like bodies formed on a base body as a conventional example.

Explanation of symbols

1 ... silicon needle 2 ... substrate (silicon wafer part)
DESCRIPTION OF SYMBOLS 10 ... Acicular body 18 ... Needle main body 31 ... Silicon wafer 34 ... Deposition layer

Claims (6)

A silicon needle provided with a plurality of needle-like bodies standing on and integrally formed on a base body,
The arrangement density per unit square millimeter of the plurality of needle-like bodies is 20 to 70 pieces / mm ² ,
The plurality of needle-like bodies are provided with a needle body having an outer diameter that gradually decreases gradually toward the tip. When the height of the plurality of needle-like bodies is H, the outer diameter at the position 1 / 3H from the tip is D ₁ , and the outer diameter at the position 2 / 3H from the tip is D ₂ , D _{1 2.} The silicon needle according to claim 1, wherein the value of the / D ₂ ratio is in the range of 0.4 or more and less than 1.0.   The silicon needle according to claim 1 or 2, wherein a height H of the plurality of needle-like bodies is 60 to 200 µm. A method of manufacturing a silicon needle comprising a plurality of needle-like bodies integrally formed on a substrate by etching a silicon wafer,
The method
Providing a mask corresponding to a location where a plurality of needle-like bodies are to be formed;
While the mask is provided, the etching step and the deposition step are repeated on the silicon wafer to form a deposition layer on the side surface serving as the basis of the needle-like body, and have a selective etching property in the height (thickness) direction. A first etching step for performing anisotropic etching;
Removing the deposited layer deposited on the side portion;
And a second etching step of performing isotropic etching on the silicon wafer.   5. The silicon needle according to claim 4, wherein the mask is a circular group mask pattern formed by oxidizing the surface of the silicon wafer or forming a silicon nitride film on the silicon wafer and then performing a photolithography method and an etching method. 6. Manufacturing method. The method for manufacturing a silicon needle according to claim 4 or 5, wherein an arrangement density of the mask pattern is 20 to 70 pieces / mm ² .

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