JP2009115501A - Micropipette, micropipette analysis apparatus, and their manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a micropipette, a micropipette analysis apparatus, and their manufacturing methods capable of improving mechanical strength, and enhancing long-term reliability and a production yield. <P>SOLUTION: The micropipette includes a substrate 101 formed of single-crystal silicon and a hollow structure 103 constituted of silicon-oxide wall surfaces. A part of the hollow structure 103 is arranged in the substrate 101 formed of single-crystal silicon to enable the administration or suction of a small amount of liquid or the like from a pipette 102, at a tip of the hollow structure 101 and the operation of small particles such as cells and small objects including small mechanical components. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a micropipette used for administration or aspiration of a very small amount of liquid or gas, or particles contained therein, or manipulation of microparticles such as cells or micromachine parts. Is. The present invention also relates to analyzers using the same and methods for producing them.

  Conventionally, some microstructures are known for the purpose of administering or aspirating very small amounts of liquid. Further, a glass pipette as a holding tool is used for manipulation of minute objects such as protozoa and egg cells.

  Patent Document 1 discloses a micropipette in which a minute film displacement device and a flow path are formed on a silicon substrate, the silicon substrate is sandwiched between two glass plates, and a pipette tip is attached to the end of the flow path. .

Patent Document 2 discloses a micropipette using two silicon substrates. In this document, a groove is formed in two silicon substrates, and the two silicon substrates are faced to each other to perform high-temperature silicon direct bonding to form a silicon hollow structure. Next, a through-hole is opened in the hollow structure to oxidize the inner wall surface of the hollow structure, and then only unnecessary silicon is selectively etched to produce a micropipette.
JP-A-10-318150 Japanese Patent Laid-Open No. 10-076168

  All the conventional methods for producing micropipettes use a bonding process, so that the mechanical strength is low, and it is difficult to increase the long-term reliability and manufacturing yield. Furthermore, since a plurality of silicon substrates or glass substrates are used, there is a limit to cost reduction compared to a single silicon substrate.

  In particular, since the pipette tip has a very small size, the mechanical strength of the bonding portion between the pipette tip and the substrate end surface is weak, and there is a limit to increase long-term reliability and manufacturing yield. is there. In addition, since the area of the bonding portion between the pipette tip and the substrate end surface is very small, difficult operations are involved in the bonding process, such as high alignment accuracy and control of the application amount of a small amount of adhesive. Increasing the pipette tip size to increase long-term reliability and manufacturing yield increases the internal volume of the pipette tip, making it difficult to handle minute amounts of liquid and the like.

  On the other hand, since the thing of patent document 2 has a high temperature thermal oxidation process after bonding a silicon substrate, circuit parts, such as a film drive device, an arithmetic circuit, and a drive circuit, can be made on a silicon substrate before bonding. Can not. In addition, when a circuit portion is formed on a silicon substrate after bonding, the thickness of the substrate increases, so that a step of thinning the substrate before bonding is required, and there is a problem that the manufacturing yield is significantly reduced.

  An object of the present invention is to provide a micropipette, a micropipette analyzer, and a method for manufacturing the same that can improve mechanical strength and improve long-term reliability and manufacturing yield.

  The micropipette of the present invention has a substrate made of single crystal silicon and a hollow structure formed of a wall surface of silicon oxide, and a part of the hollow structure is disposed inside the substrate made of single crystal silicon. It is characterized by being.

  The micropipette analyzer of the present invention includes the micropipette, and includes a light guide part for introducing light at positions on both sides of the hollow structure of the substrate, and light from the light guide part. A sensor portion that receives light through the structure is provided.

Further, the micropipette manufacturing method of the present invention includes a step of partially forming porous silicon on a silicon substrate, a step of forming a first silicon layer on the porous silicon,
Removing the porous silicon to form a hollow portion; and oxidizing the wall surface of the hollow portion through perforations communicating with the hollow portion to form a hollow structure having a wall surface made of silicon oxide. And a step of removing a part of the silicon substrate and exposing a part of the hollow structure from the silicon substrate.

  Furthermore, the method for manufacturing a micropipette analyzer of the present invention includes a step of forming porous silicon partially on a silicon substrate, a step of forming a first silicon layer on the porous silicon, and the porous material. Removing silicon and forming a hollow portion; oxidizing a wall surface of the hollow portion through a perforation communicating with the hollow portion; forming a hollow structure having a wall surface made of silicon oxide; and Forming a sensor part for receiving light on a silicon substrate; removing a part of the silicon substrate; exposing a part of the hollow structure from the silicon substrate; and part of the silicon substrate. And removing and forming a light guide part for introducing light into the sensor part through the hollow structure.

  According to the present invention, since a bonding process is not used in the manufacturing process, mechanical strength can be improved, and long-term reliability and manufacturing yield can be increased. Moreover, since it can be manufactured with one silicon substrate, cost reduction can be realized. Furthermore, even if the pipette part is a minute size, there is no adhesive surface, so that the problem of mechanical strength can be reduced.

  Next, the best mode for carrying out the invention will be described in detail with reference to the drawings.

(Embodiment 1)
FIG. 1 is a cross-sectional view showing a micropipette according to Embodiment 1 of the present invention. In the figure, 101 is a silicon substrate made of single crystal silicon, and 103 is a hollow structure composed of silicon oxide wall surfaces. As shown in FIG. 1, a part of the hollow structure 103 is disposed inside the single crystal silicon substrate 101. Further, the front and back surfaces of the silicon substrate 101 near the end of the hollow structure 103 are etched, and a part of the hollow structure 103 is exposed from the silicon substrate 101 to form a pipette portion 102.

  On the upper part of the hollow structure 103, a pressure generating device including a lower electrode 107, a piezoelectric body 105, and an upper electrode 108 is disposed, and is driven by a signal from the circuit unit 104 formed on the silicon substrate 101. be able to. Then, the diaphragm 106 is vibrated by driving the piezoelectric body 105, and a sample such as liquid, gas, or particles contained in the pipette 102 can be sucked or discharged.

  Next, the manufacturing method of the micropipette of this embodiment is demonstrated. FIG. 2 is a cross-sectional view showing the manufacturing process of the micropipette of this embodiment. First, in the step shown in FIG. 2A, a mask 202 that covers all parts other than a region where a hollow structure is to be formed is formed on a silicon substrate 201 made of single crystal silicon by photolithography. As the mask material, a polyimide film, a nitride film, an acid resistant resist, or the like that is highly resistant to hydrogen fluoride used in anodizing treatment described later is suitable.

  Next, in the step shown in FIG. 2B, the porous silicon 203 is formed through the portion where the single crystal silicon which is the opening of the mask is exposed. The porous silicon 203 is formed, for example, by performing anodization treatment (anodization) in an electrolytic solution (chemical conversion solution). As the electrolytic solution, for example, a solution containing hydrogen fluoride, a solution containing hydrogen fluoride and ethanol, a solution containing hydrogen fluoride and isopropyl alcohol, and the like are suitable. In the present embodiment, a solution in which a 49% hydrofluoric acid solution and an alcohol solution are mixed at a ratio of 1: 1 is used.

  The porosity of the porous silicon 203 is controlled by the current density during anodization, and the film thickness is controlled by the anodization time. The porous silicon 203 may be a single-layer porous silicon layer having a constant porosity or a plurality of porous silicon layers having different porosities. In order to grow episilicon described later, it is desirable that the porosity of the portion other than the surface is larger than the porosity of the porous silicon on the surface side. The thickness of the porous silicon 203 determines the height of the micropipette and the hollow structure. In this embodiment, it is about 5 to 20 μm.

  Next, in the step shown in FIG. 2C, after the mask 202 is peeled off, single crystal silicon is epitaxially grown to form a first silicon layer 204. At this time, since it is important to epitaxially grow the porous silicon 203 under a condition that does not melt, the substrate temperature during the epitaxial growth is desirably 900 ° C. or higher and 1000 ° C. or lower.

  Note that the first silicon layer 204 is not necessarily made of epitaxially grown single crystal silicon. That is, non-single crystal silicon such as polycrystalline silicon or amorphous silicon may be used as long as silicon oxide can be formed by thermal oxidation described later. If the first silicon layer 204 can be formed of epitaxial single crystal silicon, it is possible to form a drive circuit and a control circuit that are small in size, have little variation, and can perform high-speed processing. In this embodiment, single crystal silicon having a thickness of 2 μm is formed.

  Next, in the step shown in FIG. 2D, the porous silicon 203 is removed by gas etching or wet etching to form a hollow portion 205 ′. First, a hole (not shown) communicating with the porous silicon 203 is formed in a part of the first silicon layer 204. The porous silicon 203 is removed using an etching gas or solution through the perforations communicating with the porous silicon 203.

  Alternatively, the porous silicon 203 can be removed by heat treatment in a reducing atmosphere to form the hollow portion 205 ′. That is, when the silicon substrate 201 is heat-treated under a predetermined condition, for example, heat-treated at 1100 ° C. for 3 hours, silicon constituting the porous silicon 203 migrates to form a hollow portion 205 ′.

  At this time, the heat treatment atmosphere is preferably hydrogen. However, when the first silicon layer 204 is formed, the porous silicon 203 is sealed while hydrogen is taken in. Therefore, even if the heat treatment is performed in a nitrogen atmosphere, migration is not caused. Occurs and a hollow portion 205 'is formed. In the case of heat treatment, after forming the hollow portion 205 ′, a part of the first silicon layer 204 is etched to form perforations (not shown) communicating with the hollow portion 205 ′.

  2E, a silicon oxide (oxide film) 26 is formed by wet thermal oxidation. That is, silicon that is the wall surface of the hollow structure 205 is oxidized through a perforation (not shown) to form a silicon oxide (oxide film) 26. At this stage, a hollow structure 205 having a hollow interior and made of silicon oxide wall surfaces is formed. In this embodiment, the thickness of the silicon oxide (oxide film) 26 is about 2 μm. The perforation (not shown) refers to a perforation communicating with the hollow portion 205 ′ (porous silicon 203) formed in the step of FIG.

  Next, in the step shown in FIG. 2F, the first silicon layer 204, the hollow structure 205, and a part of the silicon substrate 201 are diced or etched to form the groove 207.

  Further, in the step shown in FIG. 2G, the silicon oxide on the front surface and back surface of the silicon substrate 201 is patterned to expose the silicon surface. Next, the silicon substrate 201 is partially etched to form openings 209 on the front and back sides, and a portion of the silicon oxide (pipette portion 208) that is the wall surface of the hollow structure 205 is exposed. For example, only the silicon portion can be etched by gas etching using a chlorine-based gas or anisotropic etching of silicon by alkali or the like.

  Finally, the chip is cut by dicing and separated. A micropipette can be manufactured by the above manufacturing process.

  The circuit unit 104 in FIG. 1 is formed by using a general CMOS technique after partially removing silicon oxide between the steps in FIGS. 2E and 2F, for example. In addition, the pressure generating device including the lower electrode 107, the piezoelectric body 105, and the upper electrode 108 is formed on the silicon substrate 201, for example, after the step of FIG.

  In this embodiment, a mechanical bonding process such as wafer bonding of a silicon substrate is not used in the manufacturing process. Therefore, the mechanical strength of the pipette unit 102 and the hollow structure 103 is high, and long-term reliability and manufacturing yield are achieved. It becomes possible to make it higher. In addition, there is no problem of mechanical strength because the pipette portion is not adhered even if it has a minute size. Furthermore, since it is not necessary to increase the size of the pipette portion in order to increase the manufacturing yield, the volume inside the pipette can be reduced, and it is easy to handle a very small amount of liquid.

  Further, since it can be formed with one silicon substrate, cost reduction can be realized. Furthermore, when two silicon substrates are bonded together, the substrate needs to be thinned for processing by a conventional semiconductor processing apparatus. However, according to the present embodiment, this is not necessary, so that the manufacturing yield can be reduced. Absent.

  Furthermore, since the hollow structure 103 is formed in the silicon substrate without using the glass substrate, it is possible to form an integrated circuit with a processing accuracy of 1 μm or less using the silicon integrated circuit technology. Since there is no high-temperature process after the thermal oxidation step, a film driving device, an arithmetic circuit, a driving circuit, etc. can be freely formed on the silicon substrate. Therefore, the drive circuit and control circuit that are small in size and have little variation and can perform high-speed processing, and the pipette unit and the hollow structure connected thereto can be mounted together. As described above, a small and low-cost micropipette with high mechanical strength and long-term reliability can be realized.

(Embodiment 2)
FIG. 3 is a cross-sectional view showing a micropipette analyzer according to Embodiment 2 of the present invention. As in FIG. 1, a part of a hollow structure 303 made of a silicon oxide wall surface is disposed inside a silicon substrate 301. Further, the front and back surfaces of the silicon substrate 301 near the end of the hollow structure 303 are etched, and a part of the hollow structure 303 is exposed from the silicon substrate 301 to form a pipette portion 302.

  Further, the back surface of the silicon substrate 301 near the center of the hollow structure 303 is etched, and the hollow structure 303 is exposed to form a light guide portion 306. And the sensor part 305 which is a photoelectric conversion apparatus is arrange | positioned in the position facing the light guide part 306 on both sides of the hollow structure 303. FIG. That is, the light guide unit 306 and the sensor unit 305 are disposed opposite to each other at positions on both sides of the hollow structure 303.

  The sensor unit 305 receives the light introduced from the introduction unit 306 through the hollow structure 303. A signal can be sent from the sensor unit 305 to the circuit unit 304 formed on the silicon substrate 301. Therefore, the analysis unit including the circuit unit 304 and the sensor unit 305 is integrally formed on the silicon substrate.

  Since the circuit unit 304 can perform arithmetic processing and element selection processing, an analysis unit including a plurality of pairs of micropipettes and sensor units 305 and the circuit unit 304 can be formed on a single silicon substrate.

  Further, as in the embodiment of FIG. 1, liquid and particles contained in the liquid can be sucked from the tip of the pipette unit 302 by capillary force. Further, as in FIG. 1, a pressure generating device having the piezoelectric body 105, upper and lower electrodes, etc. is disposed on the hollow structure 303, and by driving the pressure generating device, the pipette unit 302 supplies liquid, gas, or the like. The contained particles may be sucked or discharged.

  Furthermore, it is possible to measure the absorbance of the sample moving in the hollow structure 303 by irradiating light from a light source (not shown) and receiving light by the sensor unit 305. In that case, if the light source is an external light source, it may be split into monochromatic light, or the wavelength may be freely selected. Further, when a sample such as a sucked liquid or gas or particles contained therein moves in the hollow structure 303 and reaches the light guide unit 306, the absorbance of the sample is measured by the sensor unit 305. Can do.

  Here, as a manufacturing method of the micropipette analyzer of FIG. 3, first, a micropipette is manufactured by the process shown in FIG. At that time, the circuit unit 304 and the sensor unit 305 in FIG. 3 use a general CMOS technology or the like after the silicon oxide is partially removed between the processes in FIGS. 2E and 2F. Form. The circuit unit 304 and the sensor unit 305 are connected by a wiring (not shown). The light guide unit 306 is formed by etching at the same time as the etching of the opening 209 in the step of FIG.

  In this embodiment, since there is no high-temperature process after the thermal oxidation step, a light receiving element and the like can be freely formed on a single silicon substrate in addition to a film driving device, an arithmetic circuit, and a driving circuit. Thereby, a micropipette analyzer capable of analyzing a small sample at a low cost can be obtained. In addition, since a single silicon substrate can be used, a process for thinning the substrate for forming a circuit portion or the like is not necessary, and the manufacturing yield is not reduced.

(Embodiment 3)
FIG. 4A is a cross-sectional view showing a micropipette analyzer according to Embodiment 3 of the present invention, and FIG. 4B is a cross-sectional view taken along the line AA ′ of FIG. The position of the light guide is different from that of the analyzer of FIG. 3, a light guide 406 is formed inside the silicon substrate 401, and light is introduced into the hollow structure 403 from the window 407 through the light guide 406.

  That is, as in FIGS. 1 and 3, a part of the hollow structure 403 made of a silicon oxide wall surface is disposed inside the silicon substrate 401. The front and back surfaces of the silicon substrate 401 near the end of the hollow structure 403 are etched, and a part of the hollow structure 403 is exposed from the silicon substrate 401 to form a pipette portion 402.

  In addition, a sensor unit 405 that is a photoelectric conversion device and a light guide unit 406 are disposed opposite to each other on both sides of the hollow structure 403, and a signal from the sensor unit 405 is a circuit unit 404a that performs arithmetic processing on the silicon substrate 401. Can be sent to. In FIG. 4B, a part of the circuit portion 404a of FIG. 4A appears as a circuit portion 404b in the AA ′ cross section, but the arrangement of the rotating portion is not particularly limited. .

  The light guide unit 406 is connected to the window 407, and light can be introduced into the light guide unit 406 from an external light source (not shown) through the window 407. The light guide unit 406 is, for example, an optical fiber made of silicon oxide or porous silicon oxide. Impurities are partially added to the optical fiber by an ion implantation apparatus or the like, and the refractive index is differentiated between the central portion and the end portion as in the conventional optical fiber.

  In addition, as in FIGS. 1 and 3, the liquid and particles contained in the liquid can be sucked by the capillary force from the tip of the pipette unit 402. Furthermore, by arranging a pressure generator (not shown) on the silicon substrate in the same manner as in FIG. 1, it is possible to suck or discharge liquid, gas, or particles contained therein from the pipette unit 402.

  Furthermore, it is possible to measure the absorbance of the sample moving in the hollow structure 403 by irradiating the window 407 with light from a light source such as a light emitting diode or laser diode (not shown) and receiving the light with the sensor unit 405. . When the sample such as the sucked liquid or gas or the particles contained therein moves in the hollow structure 403 and reaches between the light guide unit 406 and the sensor unit 405, the sensor unit 405 measures the absorbance of the sample. be able to.

  Here, the manufacturing method of the analysis apparatus of FIG. 4 is the same as the manufacturing method described with reference to the analysis apparatus of FIGS. 2 and 3, but it is necessary to form the light guide 406 and the like inside the silicon substrate. A method of forming the light guide unit 406 will be briefly described with reference to FIG.

  After forming the hollow portion 205 ′ in the step shown in FIG. 2D, a mask that covers the entire portion other than the region where the light guide portion 406 is formed is formed by photolithography, and porous silicon is formed in the same manner as described above. . Further, a single crystal silicon layer is formed.

  Next, since the porous silicon formed in the region of the light guide unit 406 is also oxidized by wet thermal oxidation in the process shown in FIG. 2E, and light is reflected at the interface with the region other than the light guide unit, Good light transmission efficiency can be obtained. The light transmission efficiency can be increased by selecting the porosity or combining a plurality of porous layers.

  In this embodiment, since there is no high-temperature process after the thermal oxidation step, an optical fiber serving as a light guide unit can be freely made on the silicon substrate in addition to the film driving device, the arithmetic circuit, the driving circuit, and the light receiving element. . In addition, since light can be introduced into the hollow structure 403 by an optical fiber serving as a light guide portion, the position of the window 407 through which light enters can be freely selected. That is, as shown in FIG. 4B, it is not necessary to etch the silicon substrate 401 from the back surface, and the manufacturing process is simplified. Therefore, the cost can be further reduced by reducing the number of masks and improving the manufacturing yield.

  As described above, a micropipette analyzer capable of analyzing a sample with a small size and at a lower cost can be obtained.

It is sectional drawing which shows the micropipette which concerns on Embodiment 1 of this invention. It is sectional drawing which shows the manufacturing process of the micropipette which concerns on Embodiment 1 of this invention. It is sectional drawing which shows the micropipette analyzer which concerns on Embodiment 2 of this invention. It is sectional drawing which shows the micropipette analyzer which concerns on Embodiment 3 of this invention.

Explanation of symbols

101, 201, 301, 401 Silicon substrate 102, 302, 402 Pipette part 103, 303, 403 Hollow structure 104, 304, 404 Circuit part 105 Piezoelectric body 106 Diaphragm 107 Lower electrode 108 Upper electrode 202 Mask 203 Porous silicon 204 First 1 Silicon layer 205 Hollow structure 205 ′ Hollow part 206 Oxide film 207 Groove 208 Pipette part 209 Opening part 305, 405 Sensor part 306, 406 Light guide part 407 Window

Claims (6)

It has a substrate made of single crystal silicon and a hollow structure made of silicon oxide wall, and a part of the hollow structure is arranged inside the substrate made of single crystal silicon, Micropipette to be used. The micropipette according to claim 1, further comprising a pressure generator on an upper portion of the hollow structure. 3. The micropipette according to claim 1, further comprising a circuit unit that drives the pressure generating device on the substrate. A light guide part that includes the micropipette according to any one of claims 1 to 3 and that introduces light to positions on both sides of the hollow structure of the substrate, and light from the light guide part A micropipette analyzer comprising a sensor unit that receives light through a hollow structure. Forming porous silicon partially on a silicon substrate;
Forming a first silicon layer on the porous silicon;
Removing the porous silicon to form a hollow portion;
Oxidizing the wall surface of the hollow portion through a perforation communicating with the hollow portion, and forming a hollow structure having a wall surface made of silicon oxide;
Removing a part of the silicon substrate and exposing a part of the hollow structure from the silicon substrate;
A method for producing a micropipette, comprising: Forming porous silicon partially on a silicon substrate;
Forming a first silicon layer on the porous silicon;
Removing the porous silicon to form a hollow portion;
Oxidizing the wall surface of the hollow portion through a perforation communicating with the hollow portion, and forming a hollow structure having a wall surface made of silicon oxide;
Forming a sensor part for receiving light on the silicon substrate;
Removing a part of the silicon substrate and exposing a part of the hollow structure from the silicon substrate;
Removing a part of the silicon substrate and forming a light guide part for introducing light into the sensor part through the hollow structure;
A method for manufacturing a micropipette analyzer, comprising:

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