Synthetic quartz glass substrate for microchannel device, microchannel device made of synthetic quartz glass and method for producing same

Abstract

To provide a synthetic quartz glass substrate for micro flow channel devices, in which jointing according to optical contact can be applied, adhesion of a joint interface is high, and defects such as non-jointing and breakage of a substrate and faults of catching air bubbles in the joint interface do not occur, in manufacturing micro flow channel devices.SOLUTION: In a synthetic quartz glass substrate for micro flow channel devices, the maximum value of an annular average power spectrum density of a space frequency 0.4 mm-1 to 100 mm-1 obtained by measuring an arbitrary region of 6.0 mm×6.0 mm on a surface of the synthetic quartz glass substrate by using a white interferometer, is 5.0×1015 nm4 or less.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a synthetic quartz glass substrate for a microchannel device, a synthetic quartz glass microchannel device, and a method for manufacturing the same, and more specifically to a synthetic quartz glass substrate for a microchannel device that can improve adhesion at a bonding interface, a synthetic quartz glass microchannel device, and a method for manufacturing the same. [Background technology]

[0002] Microfluidic devices are devices that can perform a variety of chemical and biological operations, such as mixing, reaction, separation, purification, incubation, measurement, and detection, using extremely small amounts of samples. In microfluidic devices, functional regions with various functions, such as reaction regions in which reagents are placed in channels called microchannels, can be provided to make them suitable for a variety of applications. Applications of microfluidic devices include biological material analysis, DNA testing, drug discovery and development, organic synthesis, environmental analysis, food quality analysis, and measuring instruments.

[0003] In such microfluidic devices, chemical and biological operations such as mixing, reaction, separation, purification, incubation, measurement, and detection are carried out in a microscale space. This allows for a high-speed and highly accurate operation due to a large ratio of surface area to sample volume, which reduces environmental load, time, and cost, and saves space.

[0004] A microchannel device typically comprises a pair of substrates bonded to face each other, with fine channels formed on the bonding surface of at least one of the substrates. As the substrate, a glass substrate such as synthetic quartz glass or borosilicate glass, a silicone resin substrate such as polydimethylsiloxane (PDMS), a silicon substrate, etc. are used. In particular, a glass substrate is excellent in optical properties, chemical resistance, weather resistance, long-term stability, low substance adsorption, etc., and among them, a synthetic quartz glass substrate is most suitable as a substrate for a microchannel device.

[0005] In the manufacture of glass microfluidic devices, one method for bonding two glass substrates for microfluidic devices is heat fusion, which forms Si-O-Si siloxane bonds between the glass surfaces through heat treatment, making it possible to bond the substrates so firmly that they cannot be separated.

[0006] In order to improve the adhesion of the bonding interface in bonding by heat fusion, the bonding surfaces of the glass substrates for microchannel devices to be bonded must be sufficiently smooth. If the bonding surfaces of the substrates are not sufficiently smooth, defects such as failure to bond or air bubbles being trapped at the bonding interface may occur. In order to prevent such problems, it is common to use a glass substrate for microchannel devices whose bonding surface has been smoothed by polishing. Patent Document 1 proposes a glass substrate for microchannel devices in which the in-plane plate thickness difference is 3 μm or less and waviness in the measurement wavelength range of 0 to 5 mm is smoothed to 2 nm or less. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2008-56496 A Summary of the Invention [Problem to be solved by the invention]

[0008] However, in the glass substrate for microchannel devices described in Patent Document 1, bonding by thermal fusion requires heat treatment in a state in which the bonding surfaces are pressed by the weight of a pressure jig (a weight made of ceramic material such as alumina), which is not satisfactory in terms of productivity. Furthermore, problems such as damage to the substrate and transfer of the surface irregularities of the pressure jig to the substrate may occur.

[0009] The present invention has been made in view of the above circumstances, and has an object to provide a synthetic quartz glass substrate for microchannel devices which can be bonded by optical contact when manufacturing a microchannel device, has high adhesion at the bonding interface, and is free of defects such as non-bonding, damage to the substrate, and the formation of air bubbles at the bonding interface. [Means for solving the problem]

[0010] As a result of intensive research into achieving the above object, the inventors of the present invention have found that a spatial frequency of 0.4 mm is obtained by measuring an arbitrary area of ​​6.0 mm×6.0 mm on the surface of a synthetic quartz glass substrate (the surface to be bonded by optical contact) with a white light interferometer. -1 More than 100mm -1 The maximum annular mean power spectral density is 5.0×10 15 nm 4 The inventors have found that the synthetic quartz glass substrate described below is suitable for use in microchannel devices because it can be bonded by optical contact and can increase the adhesion of the bonding interface, which has led to the invention. Optical contact is a technique for bonding smooth glass surfaces by simply pressing them together, and is based on the van der Waals forces between the glass surfaces or hydrogen bonds between surface silanol groups formed by the adsorption of water.

[0011] That is, the present invention provides 1. A 6.0 mm × 6.0 mm arbitrary area on the surface of a synthetic quartz glass substrate is measured with a white light interferometer to obtain a spatial frequency of 0.4 mm. -1 More than 100mm -1 The maximum annular mean power spectral density is 5.0×10 15 nm 4 A synthetic quartz glass substrate for a microchannel device, which is 2. The synthetic quartz glass substrate for microchannel devices according to 1, wherein the arithmetic mean roughness (Ra) of an arbitrary region of 10 μm × 10 μm on the surface of the synthetic quartz glass substrate measured with an atomic force microscope is 1.0 nm or less. 3. A method for producing a synthetic quartz glass microchannel device comprising a laminate having a bonding surface in which two or more synthetic quartz glass substrates are bonded together, and a groove is formed in at least one of the surfaces constituting the bonding surface, comprising: a preparation step of preparing the synthetic quartz glass substrate for a microchannel device according to 1 or 2 as the two or more synthetic quartz glass substrates; a groove forming step of forming a groove on at least one of the surfaces that will form the bonding surface of the two or more synthetic quartz glass substrates that have been prepared; a bonding step of bonding two or more synthetic quartz glass substrates after the groove forming step by optical contact so that the surfaces on which the grooves are formed constitute bonding surfaces to produce a laminate; A method for producing a microchannel device made of synthetic quartz glass, comprising: 4. The method for producing a synthetic quartz glass microchannel device according to claim 3, further comprising a heat fusion step of heat fusion bonding the laminated synthetic quartz glass substrates after the bonding step. 5. The method for producing a synthetic quartz glass microchannel device according to 4, wherein the heat fusion temperature is 1000°C or higher and lower than 1600°C. 6. A synthetic quartz glass microchannel device comprising a laminate having a bonding surface in which two or more synthetic quartz glass substrates are bonded together, and a groove is formed in at least one of the surfaces constituting the bonding surface, A spatial frequency of 0.4 mm is obtained by measuring an arbitrary area of ​​6.0 mm × 6.0 mm on the surface constituting the bonding surface with a white light interferometer. -1 More than 100mm -1 The maximum annular mean power spectral density is 5.0×10 15 nm 4 is as follows: a synthetic quartz glass microchannel device in which the surfaces of the two or more synthetic quartz glass substrates are bonded together by optical contact; 7. A synthetic quartz glass microchannel device comprising a laminate having a bonding surface in which two or more synthetic quartz glass substrates are bonded together, and a groove is formed in at least one of the surfaces constituting the bonding surface, A spatial frequency of 0.4 mm is obtained by measuring an arbitrary area of ​​6.0 mm × 6.0 mm on the surface constituting the bonding surface with a white light interferometer. -1 More than 100mm -1 The maximum annular mean power spectral density is 5.0×10 15 nm 4 is as follows: a synthetic quartz glass microchannel device in which the surfaces of the two or more synthetic quartz glass substrates are bonded together by thermal fusion; 8. A synthetic quartz glass microchannel device according to claim 6 or 7, wherein the arithmetic mean roughness (Ra) of an arbitrary region of 10 μm×10 μm on the surface constituting the bonding surface, as measured by an atomic force microscope, is 1.0 nm or less. to provide. Effect of the Invention

[0012] According to the present invention, by applying optical contact bonding in the manufacture of microchannel devices, it is possible to increase the adhesion of the bonding interface of synthetic quartz glass substrates, prevent defects such as non-bonding, damage to the substrates, and defects such as air bubbles being trapped at the bonding interface, and manufacture microchannel devices with high productivity. [Brief description of the drawings]

[0013] [Figure 1]1A and 1B are schematic diagrams showing an example of a microchannel device manufactured using a synthetic quartz glass substrate for microchannel devices according to the present invention, in which (A) is an exploded perspective view of the microchannel device, (B) is a plan view of the microchannel device, (C) is a cross-sectional view taken along line CC' in (B), and (D) is a cross-sectional view taken along line D-D' in (B). [Diagram 2] 1A and 1B are schematic diagrams showing another example of a microchannel device manufactured using a synthetic quartz glass substrate for a microchannel device according to the present invention, in which (A) is an exploded perspective view of the microchannel device, (B) is a plan view of the microchannel device, (C) is a cross-sectional view taken along line CC' in (B), and (D) is a cross-sectional view taken along line D-D' in (B). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The present invention will now be described in further detail. [Synthetic quartz glass substrates for microfluidic devices] In the manufacture of a microchannel device, the synthetic quartz glass substrate for a microchannel device of the present invention is designed to have sufficient adhesion at the bonding interface when bonding by optical contact, and is measured with a white light interferometer over an arbitrary area of ​​6.0 mm x 6.0 mm on the surface (the surface to be bonded by optical contact) to obtain a spatial frequency of 0.4 mm. -1 More than 100mm -1 The maximum annular mean power spectral density is 5.0×10 15 nm 4 The following is the result.

[0015] The annular average power spectral density PSD(f), which is a function of spatial frequency f, is calculated from the discrete Fourier transform F(u,v) of the surface profile Z(Px,Py) of the synthetic quartz glass substrate. F(u,v) is calculated by the following equation (1).

[0016]

number

[0017] Here, Nx and Ny are the number of measurement points in the x and y directions when measuring the surface shape of the synthetic quartz glass substrate. Px and Py are integers indicating the position of each measurement point in the x and y directions, with values ​​of Px = 0, 1, . . ., Nx-1 and Py = 0, 1, . . ., Ny-1. In contrast, u and v take the values ​​of u = -1 / 2, -1 / 2 + 1 / Nx, . . ., 1 / 2 and v = -1 / 2, -1 / 2 + 1 / Ny, . . ., 1 / 2.

[0018] The power spectral density P(u,v) can be obtained by normalizing F(u,v) using the measurement pitch Δx, Δy in the x and y directions and the area of ​​the measurement area A = (NxΔx) × (NyΔy) as shown in the following formula (2). Note that without this normalization, it is not possible to simply compare power spectral densities calculated under different measurement area and measurement pitch conditions.

[0019]

number

[0020] On the other hand, the spatial frequency f(u,v) is expressed by the following equation (3).

[0021]

number

[0022] The annular average power spectral density PSD(f) is obtained by averaging the power spectral density P(u,v) with respect to the spatial frequency f(u,v) as shown in the following equation (4).

[0023]

number

[0024] Here, Nf is the number of measurement points that satisfy the following equation (5).

[0025]

number

[0026] If NxΔx=NyΔy, Δf is defined by the following equation (6).

[0027]

number

[0028] The synthetic quartz glass substrate for microchannel devices of the present invention has a spatial frequency of 0.4 mm, which is obtained by measuring an arbitrary area of ​​6.0 mm × 6.0 mm on the substrate surface with a white light interferometer. -1 More than 100mm -1 The maximum value of the annular average power spectral density PSD(f) is 5.0×10 15 nm 4 or less, but preferably 2.0×10 15 nm 4 Less than or equal to 1.0×10 15 nm 4 Less than 1.0×10, more preferably 14 nm 4 The following is the result. If the annular average power spectral density PSD(f) exceeds this range, good adhesion cannot be maintained at the bonding interface during bonding by optical contact, and the layers may not be able to be fixed by optical contact, or even if they are fixed, the bonding strength may be insufficient, resulting in problems such as air bubbles being trapped at the bonding interface. In the present invention, it is sufficient that at least one of the two surfaces (main surfaces) of the synthetic quartz glass substrate (the surface to be joined by optical contact) has the above-mentioned characteristics, but when both surfaces are to be joined by optical contact, it is preferable that both surfaces have the above-mentioned characteristics. The white light interferometer may be appropriately selected from conventionally known interferometers, and a specific example thereof may be NexView manufactured by Zygo.

[0029] Furthermore, the arithmetic mean roughness (Ra) obtained by measuring an arbitrary area of ​​10 μm × 10 μm on the surface of the synthetic quartz glass substrate of the present invention (the surface to be bonded by optical contact) with an atomic force microscope is not particularly limited as long as optical contact is possible, but is preferably 1.0 nm or less, more preferably 0.5 nm or less, even more preferably 0.4 nm or less, and even more preferably 0.3 nm or less. If the arithmetic mean roughness (Ra) is within this range, the adhesion of the bonding interface can be maintained better in bonding by optical contact, and it is possible to suppress problems such as air bubbles being trapped at the bonding interface due to insufficient bonding strength even when the layers cannot be fixed by optical contact or when the layers can be fixed by optical contact. In the present invention, of the two surfaces (main surfaces) of the synthetic quartz glass substrate, it is preferable that the surface to be joined by optical contact has the above-mentioned average roughness, but when both surfaces are to be joined by optical contact, it is more preferable that both surfaces have the above-mentioned average roughness. The atomic force microscope may be appropriately selected from conventionally known ones, and a specific example thereof is NANO-IM-8 manufactured by PACIFIC NANOTECHNOLOGY.

[0030] The shape of the synthetic quartz glass substrate of the present invention is not particularly limited, but may be a quadrangle such as a rectangle, a circle, etc., from the viewpoint of ease of manufacture. For example, a quadrangle substrate having a side length of 10 to 1000 mm is preferably used, and a circle substrate having a diameter of 10 to 1000 mm is preferably used. In the case of a large synthetic quartz glass substrate, a groove that will become a flow channel of a microchannel device is formed by etching, laser processing, etc., and then cut by a method such as mechanical cutting or laser cutting, so that a large number of microchannel devices can be manufactured at once. In the case of a small synthetic quartz glass substrate, a high-definition lithography device can be used to form a groove that will become a flow channel, so that a microchannel device equipped with a finer flow channel can be manufactured.

[0031] The thickness of the synthetic quartz glass substrate of the present invention is not particularly limited and may be appropriately selected, but is preferably 0.01 to 300 mm, more preferably 0.1 to 100 mm, and even more preferably 0.5 to 30 mm. If the thickness is too small, it may be easily damaged during handling. Furthermore, the rigidity of the microchannel device may be insufficient, and it may be easily damaged during handling. On the other hand, if the thickness is too large, it may be difficult to stack multiple substrates. Furthermore, it may be difficult to reduce the weight of the microchannel device.

[0032] [Method of manufacturing synthetic quartz glass substrates for microchannel devices] The method for producing a synthetic quartz glass substrate for a microchannel device of the present invention is not particularly limited as long as it can produce a synthetic quartz glass substrate having the above-mentioned properties. For example, a synthetic quartz glass ingot produced by reacting a silica raw material compound such as a silane compound or a siloxane compound with an oxyhydrogen flame is molded into a desired shape, annealed, sliced ​​to a desired thickness, lapped, and if necessary polished on the periphery to obtain a raw material substrate, which is then roughly polished and precisely polished to produce a substrate.

[0033] [Rough polishing process] The rough polishing step can be carried out by using an abrasive on a polishing cloth such as a hard polyurethane foam. It is preferable that the polishing cloth has grooves formed so that the polishing agent spreads over the entire substrate. By spreading the polishing agent over the entire substrate, polishing unevenness in the surface is reduced, and the surface shape can be easily controlled. The shape of the grooves of the polishing cloth can be a stripe shape, in which a large number of solid or concave grooves are formed in parallel at a predetermined interval.

[0034] Examples of the polishing agent include those containing abrasive grains such as silica, ceria, alundum, white alundum (WA), FO, zirconia, SiC, diamond, titania, germania, etc., and among these, those containing ceria are preferred. The particle size of the polishing grains is preferably 0.1 to 10 μm, more preferably 0.5 to 3 μm, and the polishing agent can be suitably used in the form of a water slurry of these.

[0035] The polishing machine may be of either a single-sided type or a double-sided type, but generally, the double-sided type is preferable for achieving high precision finishing to even out variations in thickness and to reduce flatness of the substrate.

[0036] [Precision polishing process] The precision polishing step can be carried out using a polishing cloth such as suede-based soft polyurethane or urethane-impregnated nonwoven fabric together with an abrasive. The polishing cloth may have grooves so that the polishing agent can be distributed over the entire substrate. The polishing agent is uniformly supplied and distributed throughout the substrate, and the shavings are quickly discharged through the grooves, making it easier to control the polishing rate and surface shape. The grooves of the polishing cloth may be striped or the like.

[0037] Examples of the polishing agent include those containing abrasive grains such as colloidal silica, silica, ceria, alundum, white alundum (WA), FO, zirconia, SiC, diamond, titania, germania, etc., and among these, those containing colloidal silica are preferred. The particle size of the polishing grains is preferably 5 to 1,000 nm, more preferably 5 to 150 nm, and the polishing agent can be suitably used in the form of a water slurry of these.

[0038] The polishing machine may be of either a single-sided type or a double-sided type, but generally, the double-sided type is preferable for achieving high precision finishing to even out variations in thickness and to reduce flatness of the substrate.

[0039] [Surface shape adjustment process] A surface shape adjustment step can be appropriately performed during or before or after the precision polishing step. The surface shape adjustment step is a step of processing all or a part of the substrate surface based on previously measured surface shape data. The processing method may be any method capable of processing the substrate surface on the order of micrometers or less, and examples of the method include etching such as wet etching and dry etching, and polishing with a rotary polishing tool.

[0040] [Microfluidic Devices] In the following, one embodiment of the microchannel device of the present invention will be described with reference to the drawings. However, the drawings are schematic or conceptual, and the dimensions of each component, the sizes between components, the ratios, etc. are not necessarily the same as those in reality. Furthermore, even when the same components, etc. are shown, the dimensions and ratios between them may be represented differently depending on the drawing.

[0041] FIG. 1 shows a microchannel device 100 (hereinafter abbreviated as "device 100") according to one embodiment of the present invention. Specifically, FIG. 1(A) is an exploded oblique view of one embodiment of device 100, FIG. 1(B) is a plan view of device 100, FIG. 1(C) is a cross-sectional view along line CC' in FIG. 1(B), and FIG. 1(D) is a cross-sectional view along line D-D' in FIG. 1(B).

[0042] 1(A), device 100 comprises a first synthetic quartz glass substrate 103 (for forming a flow path) having mutually opposing surfaces 101a, 101a' and having Y-shaped grooves 102 (non-penetrating) formed on surface 101a (surface to be joined by optical contact), and a second synthetic quartz glass substrate 104 (for use as a cover) having mutually opposing surfaces 101b, 101b' and joined to surface 101a of first synthetic quartz glass substrate 103 on which grooves 102 are formed. Second synthetic quartz glass substrate 104 has through holes 105 at positions corresponding to the three ends of grooves 102.

[0043] In this embodiment, the synthetic quartz glass substrate for microchannel devices of the present invention described above is used as the first and second synthetic quartz glass substrates, and the surfaces of these two synthetic quartz glass substrates are joined by optical contact to form a laminate having a joining surface 107 as shown in Figures 1(C) and (D), with the groove portion 102 of the first synthetic quartz glass substrate and the second synthetic quartz glass substrate 104 forming the microchannel 106 of the device 100. In addition, in device 100, through-hole 105 communicates with the outside of device 100 and has the function of supplying a sample to microchannel 106 or discharging a sample from microchannel 106. The microchannels 106 of the microchannel device are formed into an appropriate shape, and samples are supplied from the through-holes 105 to perform various chemical and biological operations such as mixing, reaction, separation, purification, incubation, measurement, and detection.

[0044] 1(A), grooves 102 are formed on surface 101a of first synthetic quartz glass substrate 103, but grooves may be formed on either surface 101a of first synthetic quartz glass substrate 103 or surface 101b' of second synthetic quartz glass substrate 104, or on both. When grooves are formed on the surfaces of both substrates, grooves may be formed in corresponding shapes at corresponding positions, or grooves of different shapes may be formed at different positions, so that the grooves of both substrates match when the two substrates are bonded together. Although the number of grooves 102 in this embodiment is one, the number of grooves provided may be more than one. The cross-sectional shape of the groove pattern may be rectangular, circular, semicircular, approximately semicircular, or the like. The length, width, and depth of the microchannel 106 can be appropriately selected depending on the application of the device 100 .

[0045] Furthermore, in this embodiment, the through hole 105 is formed only in the second synthetic quartz glass substrate 104, but it may be formed only in the first synthetic quartz glass substrate, or it may be formed in both the first and second synthetic quartz glass substrates. The shape of the through hole 105 is cylindrical, but may be a prismatic shape, etc. The number of through holes may be multiple as in this embodiment, but at least one should be provided. The size (diameter or width) of the through hole 105 is not particularly limited, but from the viewpoints of manufacturing and handling, a diameter of 0.1 to 5 mm is preferable for a cylindrical shape, and a side length of 0.1 to 5 mm is preferable for a prismatic shape.

[0046] The microchannel device of the present invention is not limited to the above-described embodiment, and various modifications can be made thereto. For example, the device may have a configuration as shown in FIG. FIG. 2 shows a microchannel device 200 (hereinafter abbreviated as "device 200") according to another embodiment of the present invention. Specifically, FIG. 2(A) is an exploded oblique view of device 200 according to another embodiment, FIG. 2(B) is a plan view of device 200, FIG. 2(C) is a cross-sectional view along line CC' in FIG. 2(B), and FIG. 2(D) is a cross-sectional view along line D-D' in FIG. 2(B).

[0047] As shown in Figure 2(A), device 200 comprises a first synthetic quartz glass substrate 203 (for forming a flow path) having opposing surfaces 201a, 201a' and having Y-patterned grooves 202 (non-penetrating) formed on surface 201a (surface joined by optical contact), a second synthetic quartz glass substrate 204 (for forming a flow path and serving as a cover) having opposing surfaces 201b, 201b', bonded to surface 201a of first synthetic quartz glass substrate 203 on which grooves 202 are formed and having Y-patterned grooves 202 (non-penetrating) formed on surface 201b (surface joined by optical contact), and a third synthetic quartz glass substrate 205 (for covering) having opposing surfaces 201c, 201c', and bonded to surface 201b of second synthetic quartz glass substrate 204 on which grooves 202 are formed. The second synthetic quartz glass substrate 204 and the third synthetic quartz glass substrate 205 have through holes 206 for supplying and discharging the sample at positions corresponding to the three ends of the groove portion 202 .

[0048] In this embodiment, the synthetic quartz glass substrates for microchannel devices of the present invention described above are used as the first, second and third synthetic quartz glass substrates, and the surfaces of these three synthetic quartz glass substrates are bonded together by optical contact to form a laminate having bonding surfaces 208, 209 as shown in Figures 2(C) and (D), with groove portion 202 of the first substrate and second substrate 204, and groove portion 202 of the second substrate and third substrate 205 each forming a microchannel 207 of device 200. In addition, in device 200 , through-hole 206 communicates with the outside of device 200 and has the function of supplying a sample to microchannel 207 or discharging a sample from microchannel 207 .

[0049] 2(A), grooves 202 are formed on surface 201a of first synthetic quartz glass substrate 203 and surface 201b of second synthetic quartz glass substrate 204, but grooves may be formed on either or both of surface 201a of first synthetic quartz glass substrate 203 and surface 201b' of second synthetic quartz glass substrate 204. Similarly, grooves may be formed on either or both of surface 201b of second synthetic quartz glass substrate 201 and surface 201c' of third synthetic quartz glass substrate. When grooves are formed on both of the two surfaces to be joined, the grooves may be formed in corresponding positions with corresponding shapes so that the grooves of both substrates will match when the two substrates are joined, or different shapes may be formed in different positions. Furthermore, the number and cross-sectional shape of grooves 202 are as explained in FIG. 1, and the length, width and depth of microchannel 207 can be appropriately selected depending on the application of device 200.

[0050] Furthermore, in this embodiment, the through hole 206 is formed in the second synthetic quartz glass substrate 204 and the third synthetic quartz glass substrate 205, but it may also be formed in the first synthetic quartz glass substrate 203 and the second synthetic quartz glass substrate 204, or it may be formed in the first synthetic quartz glass substrate 203 and the third synthetic quartz glass substrate 205, or it may be formed in all of the first synthetic quartz glass substrate 203, the second synthetic quartz glass substrate 204 and the third synthetic quartz glass substrate 205. The shape and size of the through-hole 206 are as described with reference to FIG.

[0051] Although not particularly shown, for example, a microchannel device may be constructed by bonding four or more synthetic quartz glass substrates of the present invention. With such a configuration, a large number of microchannels can be stacked in parallel, resulting in a microchannel device with even greater productivity and throughput. In this case, taking into consideration the effect on optical contact caused by increased warping of the synthetic quartz glass substrates due to stacking a large number of synthetic quartz glass substrates, the number of synthetic quartz glass substrates (number of layers) is preferably 50 or less, more preferably 20 or less.

[0052] Furthermore, for example, grooves may be provided on both surfaces to be joined, or the grooves may be penetrating. By using such a configuration, the microchannels can be formed in various shapes. In addition, since a large number of microchannels can be stacked in parallel, a microchannel device with even greater productivity and throughput can be obtained.

[0053] In the microchannel device of the present invention, the synthetic quartz glass substrates bonded by optical contact can be peeled (separated) at the bonding interface without destroying them, and the bonding interface can be visually observed from above, below, or on the side of the stacked substrates. In addition, by carrying out the heat treatment described below, the surfaces of the synthetic quartz glass substrates can be thermally fused together to form a stronger bond; however, glass substrates bonded by thermal fusion cannot be peeled off (separated) without destroying them, and it may become difficult or impossible to visually observe the bonded interface from above, below, or even from the sides of the stacked substrates.

[0054] [Method of manufacturing microfluidic devices] Next, a method for producing a microchannel device using the synthetic quartz glass substrate for a microchannel device of the present invention will be described.

[0055] The microchannel device of the present invention can be produced, for example, by a method including the following steps. (1) A preparation step of preparing two or more synthetic quartz glass substrates for a microchannel device according to the present invention. (2) A groove forming step of forming a groove on at least one of the two surfaces of the two or more synthetic quartz glass substrates that will form the bonding surfaces of the microfluidic device. (3) A bonding step of bonding two or more synthetic quartz glass substrates after the groove forming step by optical contact so that the surfaces on which the grooves are formed constitute bonding surfaces to produce a laminate.

[0056] [Preparation process] In the preparation step, the synthetic quartz glass of the present invention for use in a microchannel device is prepared. Two or more, preferably three or more, synthetic quartz glass substrates are prepared depending on the application of the microchannel device to be manufactured.

[0057] [Groove formation process] In the groove forming step, a groove is formed on at least one of the two surfaces that will form the bonding surfaces of the microchannel device out of the two or more synthetic quartz glass substrates prepared. For example, as shown in FIG. 1(A), a groove 102 is formed on a surface 101a of a first synthetic quartz glass substrate 103. The grooves 102 can be formed by etching such as wet etching or dry etching, mechanical cutting using a machining center or other numerically controlled machine tools, or physical processing methods such as blasting. Among these, it is preferable to form the grooves by etching, which can achieve both high precision and productivity.

[0058] [Through hole formation process] In the present invention, it is preferable to provide a through hole forming step of forming a predetermined number of through holes at predetermined positions in the synthetic quartz glass substrate so as to correspond to the grooves formed in the groove forming step. When the through hole forming step is performed, through holes 105 can be formed in the second synthetic quartz glass substrate 104. The through holes 105 can be formed by known techniques such as mechanical cutting using a machining center or other numerically controlled machine tools, physical processing methods such as blasting, and etching methods such as wet etching and dry etching. Among these, from the viewpoint of excellent productivity, it is preferable to form the through holes by cutting using a machining center.

[0059] [Cleaning process] In the present invention, it is preferable to provide a cleaning step for cleaning the synthetic quartz glass substrate in which the grooves are formed and the synthetic quartz glass substrate in which the through-holes are formed. When a cleaning step is performed, it is preferable to properly clean the first synthetic quartz glass substrate and the second synthetic quartz glass substrate before bonding the glass substrates together. The synthetic quartz glass substrate may be cleaned by any method capable of removing particles with a width of 100 μm or more, and examples of such methods include methods using pure water, alcohol-based solvents, acidic solutions such as sulfuric acid, alkaline solutions such as ammonia water, surfactants, etc. The cleaning methods exemplified above may be performed alone or in combination. They may also be combined with ultrasonic application.

[0060] [Joining process] In the bonding step, two or more synthetic quartz glass substrates, including a synthetic quartz glass substrate having a groove formed therein, are bonded by optical contact so that the surfaces having the grooves formed therein form bonding surfaces, to produce a laminate. In this process, a first synthetic quartz glass substrate 103 having a groove 102 formed therein and a second synthetic quartz glass substrate 104 having a through hole 105 formed therein are bonded and laminated by optical contact so that the surface having the groove 102 forms the bonding surface. The step of bonding and laminating by optical contact is carried out by bringing surface 101a of first synthetic quartz glass substrate 103 and surface 101b' of second synthetic quartz glass substrate 104 into close contact with each other. Optical contact bonding allows the substrates to be separated and rebonded without damage, making the microchannels easy to clean and reprocess, and allowing them to be reused multiple times.

[0061] [Heat fusion process] In the manufacturing method of the present invention, it is preferable to provide a heat fusion step in which the synthetic quartz glass substrates that have been joined and laminated by optical contact are heat fused. When the heat fusion step is carried out, the synthetic quartz glass substrates laminated by bonding through optical contact are placed in an electric furnace and heated to a temperature of preferably 1000°C or more and less than 1600°C, more preferably 1000°C or more and 1400°C or less. This eliminates the need for heat treatment in a state in which the bonding surfaces are pressed together by the weight of a pressing tool, and prevents problems such as damage to the substrates and transfer of the surface irregularities of the pressing tool to the substrates. In addition, since no weighting step is required, productivity is improved. By carrying out the heat fusion process, Si-O-Si siloxane bonds are formed between the glass surfaces, creating a strong bond that cannot be separated. This makes it possible to prevent problems such as liquid leakage when samples are supplied at high pressure and high flow rates.

[0062] Although an embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications can be made, all of which are included in the technical scope of the present invention. EXAMPLES

[0063] The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0064] [Example 1] The sliced ​​synthetic quartz glass raw material was wrapped by a double-sided lapping machine performing planetary motion to obtain two intermediate raw materials. Thereafter, rough polishing was performed using a double-sided polishing machine with planetary motion, a hard urethane polishing cloth having strip-shaped grooves, and a cerium oxide-based abrasive. Next, precision polishing was performed using a suede-based polishing cloth and colloidal silica-based polishing agent in a double-sided polishing machine performing planetary motion, to obtain a first synthetic quartz glass substrate having a size of 6 inches Φ and a thickness of 0.5 mm.

[0065] An arbitrary area of ​​6.0 mm × 6.0 mm on the surface (surface to be bonded by optical contact) of the obtained first synthetic quartz glass substrate was measured with a white light interferometer (NexView, manufactured by Zygo, hereinafter the same) under the condition of 1240 × 1240 pixels, and a spatial frequency of 0.4 mm was obtained. -1 More than 100mm -1 The maximum annular mean power spectral density is 7.0×10 13 nm 4 It was. Furthermore, when an arbitrary region of 10 μm×10 μm on the same surface was measured with an atomic force microscope (NANO-IM-8 (manufactured by PACIFIC NANOTECHNOLOGY), the arithmetic mean roughness (Ra) was 0.21 nm.

[0066] A second synthetic quartz glass substrate was obtained in the same manner as above.

[0067] The surface of the second synthetic quartz glass substrate (the surface to be joined by optical contact) was also measured in the same way, and the spatial frequency was 0.4 mm -1 More than 100mm -1 The maximum annular mean power spectral density is 7.0×10 13 nm 4 The arithmetic mean roughness (Ra) was 0.21 nm.

[0068] A chrome film and a photoresist were formed on the surface of the first synthetic quartz glass substrate (the surface to be bonded by optical contact), and then exposure and development were carried out using a photomask to form an etching mask of a predetermined shape. Thereafter, wet etching was performed using an aqueous solution of hydrofluoric acid containing ammonium fluoride to form a groove having a maximum width of 70 μm and a depth of 30 μm and having a substantially semicircular cross section. Next, a through hole having a diameter of 1.0 mm was formed at a predetermined position of the second synthetic quartz glass substrate using a machining center. Next, the first synthetic quartz glass substrate with the grooves formed therein and the second synthetic quartz glass substrate with the through holes formed therein were washed with an aqueous potassium hydroxide solution, hot concentrated sulfuric acid, a weak alkaline surfactant, and pure water, and then dried with IPA.

[0069] Next, the surfaces (surfaces to be joined) of the first synthetic quartz glass substrate and the second synthetic quartz glass substrate were brought into close contact with each other and joined by optical contact to produce a laminate, thereby obtaining a microchannel device. When the bonding interface of the microchannel device was visually inspected, no unbonded portions, air bubbles, or the like were observed.

[0070] Next, the obtained microchannel device was heat fused at 1100° C. in an electric furnace. When the bonding interface of the microchannel device was visually inspected, no unbonded portions, air bubbles, or the like were observed.

[0071] [Example 2] Using the same procedure as in Example 1, a total of six synthetic quartz glass substrates, numbered first to sixth, were prepared. The surfaces of the first to sixth synthetic quartz glass substrates (surfaces to be joined by optical contact) were measured in the same manner as in Example 1, and the spatial frequency was 0.4 mm -1 More than 100mm -1 The maximum annular mean power spectral density is 7.0×10 13 nm 4 The arithmetic mean roughness (Ra) was 0.21 nm.

[0072] Next, a groove having a roughly semicircular cross section was formed on one surface (the surface to be joined by optical contact) of each of the first to fifth synthetic quartz glass substrates in the same manner as in Example 1. Next, through holes were formed at predetermined positions on the second to sixth synthetic quartz glass substrates using the same procedure as in Example 1. Thereafter, the first to sixth synthetic quartz glass substrates were washed and dried in the same manner as in Example 1.

[0073] Next, the grooved surface of the first synthetic quartz glass substrate and the surface facing the grooved surface of the second synthetic quartz glass substrate, the grooved surface of the second synthetic quartz glass substrate and the surface facing the grooved surface of the third synthetic quartz glass substrate, the grooved surface of the third synthetic quartz glass substrate and the surface facing the grooved surface of the fourth synthetic quartz glass substrate, the grooved surface of the fourth synthetic quartz glass substrate and the surface facing the grooved surface of the fifth synthetic quartz glass substrate, and the grooved surface of the fifth synthetic quartz glass substrate and the surface of the sixth synthetic quartz glass substrate were aligned and the surfaces (surfaces to be joined) were brought into close contact with each other and joined by optical contact, producing a laminate in which the first to sixth synthetic quartz glass substrates were stacked in sequence, and a microchannel device in which five channels were stacked was obtained. When the five bonded interfaces of the obtained microchannel device were visually inspected, no unbonded portions, air bubbles, etc. were observed at any of the bonded interfaces.

[0074] Next, the obtained microchannel device was heat-sealed in the same manner as in Example 1. When the five bonding interfaces of the microchannel device were visually inspected, no unbonded portions, air bubbles, etc. were observed at any of the bonding interfaces.

[0075] [Comparative Example 1] A first synthetic quartz glass substrate was prepared in the same manner as in Example 1. The surface of the synthetic quartz glass substrate (the surface to be joined by optical contact) was measured in the same manner as in Example 1, and the spatial frequency was 0.4 mm -1 More than 100mm -1 The maximum annular mean power spectral density is 7.0×10 13 nm 4 The arithmetic mean roughness (Ra) was 0.21 nm.

[0076] Moreover, a second synthetic quartz glass substrate was prepared in the same manner as in Example 1, except that the rough polishing time was shortened and the precision polishing time was also shortened. The surface of the obtained second synthetic quartz glass substrate (the surface to be bonded by optical contact) was measured in an arbitrary area of ​​6.0 mm × 6.0 mm with a white light interferometer in the same manner as in Example 1. The spatial frequency was 0.4 mm. -1 More than 100mm -1 The maximum annular mean power spectral density is 1.0×10 16 nm 4 It was. Furthermore, when an arbitrary region of 10 μm×10 μm on the same surface was measured with an atomic force microscope, the arithmetic mean roughness (Ra) was 0.37 nm.

[0077] Next, a groove having a roughly semicircular cross section was formed on the surface (surface to be bonded) of the first synthetic quartz glass substrate in the same manner as in Example 1. Next, through holes were formed in predetermined positions of the second synthetic quartz glass substrate in the same manner as in Example 1. Thereafter, the first synthetic quartz glass substrate with the grooves formed therein and the second synthetic quartz glass substrate with the through holes formed therein were washed and dried in the same manner as in Example 1, and the surfaces (surfaces to be joined) were brought into close contact with each other and joined by optical contact to produce a laminate, thereby obtaining a microchannel device. When the joining interface of the microchannel device was visually inspected, interference fringes and air bubbles due to non-joining were observed.

[0078] Next, the obtained microchannel device was heat-sealed in the same manner as in Example 1. When the bonding interface of the microfluidic device was visually inspected, interference fringes and bubbles due to non-bonding were observed. In addition, it was observed that the bubble area had expanded compared to before heat fusion due to the expansion of the gas inside the bubbles. [Explanation of symbols]

[0079] 100 Microfluidic Device 102 Groove 103 First synthetic quartz glass substrate (for forming flow path) 104 Second synthetic quartz glass substrate (for cover) 105 Through hole 106 Microchannel 107 Joint surface 200 Microfluidic Device 202 Groove 203 First synthetic quartz glass substrate (for forming flow path) 204 Second synthetic quartz glass substrate (for forming flow path and for cover) 205 Third synthetic quartz glass substrate (for cover) 206 Through Hole 207 Microchannel 208 Joint surface 209 Joint surface

Claims

1. A spatial frequency of 0.4 mm is obtained by measuring an arbitrary area of ​​6.0 mm x 6.0 mm on the surface of a synthetic quartz glass substrate with a white light interferometer. -1 More than 100 mm -1 The maximum value of the annular average power spectral density is 5.0×10 15 nm 4 A synthetic quartz glass substrate for a microchannel device, comprising:

2. 2. The synthetic quartz glass substrate for microchannel devices according to claim 1, wherein the arithmetic mean roughness (Ra) of any 10 μm×10 μm area on the surface of the synthetic quartz glass substrate measured with an atomic force microscope is 1.0 nm or less.

3. A method for producing a synthetic quartz glass microchannel device comprising a laminate having a bonding surface in which two or more synthetic quartz glass substrates are bonded together, and a groove is formed in at least one of the surfaces constituting the bonding surface, comprising: a preparation step of preparing a synthetic quartz glass substrate for a microchannel device according to claim 1 or 2 as the two or more synthetic quartz glass substrates, the synthetic quartz glass substrate having a surface that will constitute the bonding surface and has the annular average power spectral density; a groove forming step of forming a groove on at least one of the surfaces that will form the bonding surface of the two or more synthetic quartz glass substrates that have been prepared; a bonding step of bonding two or more synthetic quartz glass substrates after the groove forming step by optical contact so that the surfaces on which the grooves are formed constitute bonding surfaces to produce a laminate; A method for producing a microchannel device made of synthetic quartz glass, comprising:

4. 4. A method for producing a synthetic quartz glass microchannel device according to claim 3, further comprising a heat fusion step of heat fusion bonding the laminated synthetic quartz glass substrates after the bonding step.

5. 5. The method of claim 4, wherein the temperature for the heat fusion is 1000° C. or higher but lower than 1600° C.

6. A method for manufacturing a synthetic quartz glass microchannel device as described in any one of claims 3 to 5, wherein the synthetic quartz glass substrate for a microchannel device in the preparation step is obtained by forming a synthetic quartz glass ingot into a desired shape, annealing it, slicing it, lapping it, and polishing the outer periphery as necessary to obtain a raw material substrate, which is then roughly polished with a hard urethane abrasive cloth and a cerium oxide abrasive and precisely polished with a suede abrasive cloth and colloidal silica.

7. A synthetic quartz glass microchannel device comprising a laminate having a bonding surface in which two or more synthetic quartz glass substrates are bonded together, and a groove is formed in at least one of the surfaces constituting the bonding surface, A spatial frequency of 0.4 mm is obtained by measuring an arbitrary area of ​​6.0 mm x 6.0 mm on the surface constituting the bonding surface with a white light interferometer. -1 More than 100 mm -1 The maximum value of the annular average power spectral density is 5.0×10 15 nm 4 is as follows: A synthetic quartz glass microchannel device, in which the surfaces of the two or more synthetic quartz glass substrates are bonded together by optical contact.

8. A synthetic quartz glass microchannel device comprising a laminate having a bonding surface in which two or more synthetic quartz glass substrates are bonded together, and a groove is formed in at least one of the surfaces constituting the bonding surface, A spatial frequency of 0.4 mm is obtained by measuring an arbitrary area of ​​6.0 mm x 6.0 mm on the surface constituting the bonding surface with a white light interferometer. -1 More than 100 mm -1 The maximum value of the annular average power spectral density is 5.0×10 15 nm 4 is as follows: A synthetic quartz glass microchannel device in which the surfaces of the two or more synthetic quartz glass substrates are bonded together by thermal fusion.

9. 9. A synthetic quartz glass microchannel device according to claim 7 or 8, wherein the arithmetic mean roughness (Ra) of any 10 μm × 10 μm area of ​​the surface constituting the bonding surface, as measured with an atomic force microscope, is 1.0 nm or less.

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