JP2006225198A - Method for manufacturing glass substrate with groove, and chemical microchip obtained by using the substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a glass substrate with grooves the bottom face of which has nearly flat shape by a wet etching process. <P>SOLUTION: This method for manufacturing the glass substrate with grooves comprises fusion-bonding a first glass sheet and a second glass sheet, and forming the grooves by the wet etching process using hydrofluoric acid, where solubility to the acid of the second glass sheet at the bonding face with the first glass sheet and its vicinity is made less than that of the first glass sheet, and the grooves are formed by etching with hydrofluoric acid from the surface of the first glass sheet through the bonding face with the second glass sheet. Compositions of the first glass sheet and the second glass sheet may be made different from each other. Alternatively, a compressive stress layer (a layer having a specific volume smaller than that inside) may be formed at the glass surface being the bonding face of the second glass sheet and its vicinity while the compositions of the first glass sheet and the second glass sheet are made the same. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a method for producing a grooved glass substrate suitable for producing a microchemical chip incorporating a microchannel. More specifically, the present invention relates to a microchemical chip that mixes, separates, reacts, etc. a sample in a very small amount of liquid in a field such as chemical analysis, and a method for producing a grooved glass substrate used therefor.

The microchemical chip refers to a glass substrate on which a groove is formed and a second glass substrate on which a sample solution injection hole and a discharge hole are arranged at positions corresponding to the groove. In this part, a micro flow channel is formed.

The method of forming a groove with a predetermined shape to be a micro-channel on one of the two glass substrates that make up the microchemical chip is the science published by CMC Publishing “Integrated Chemistry”. Section 4.2.2 of Technology-Chapter 4 Microfabrication Technology disclosed in the chip manufacturing process (book number ISBN 4-88231-436-3). That is, a Pyrex (registered trademark) glass plate is polished to an average roughness of about 50 nm, and then heat-treated near the annealing point of the glass in order to remove residual stress existing in the vicinity of the glass surface. A method of forming a groove by chemical etching using hydrofluoric acid (hydrofluoric acid) by covering the main surface of the glass plate with a metal laminated film of Cr and Au as a masking film is described.

Section 4.2.2 of Chapter 4 Microfabrication Technology of CM Publishing “Integrated Chemistry”-Science and Technology Developed by Micro Chemical Chips (Book No. ISBN 4-88231-436-3)

Japanese Patent Application Laid-Open No. 2001-261372 discloses a method for realizing an anisotropic etching shape in order to form a microchannel on the surface of a glass substrate by wet etching using hydrofluoric acid.

JP 2001-261372 A

According to this method, it is described that a groove having a larger curvature at the bottom can be formed than a groove obtained by conventional isotropic wet etching.

A microchemical chip incorporating a microchannel is used to perform qualitative analysis and quantitative analysis of a solute in a sample solution while injecting the sample solution into the microchannel. At this time, the fluorescence emitted by the solute is extracted from the microchannel and detected, and a thermal lens is formed in the sample solution, and the detection light taken out of the microchannel through the thermal lens is measured and measured. A method such as photothermal conversion spectroscopy (thermal lens analysis) is used.

When detecting and measuring light emitted from inside the microchannel to the outside of the microchannel, the shape of the light exit surface of the microchannel affects. In other words, if the wall surface on the light emission side of the microchannel is a plane perpendicular to the light traveling direction, the light does not bend on the wall surface due to refraction or the like. The light quantity can be accurately measured by being guided to the photodetector set in (1). However, if the wall surface of the microchannel is a curved surface, the optical path is bent depending on the position where the light exits the microchannel, and there is a problem that the light quantity measurement cannot be performed with good reproducibility.

A groove formed by a chemical (wet) etching method using hydrofluoric acid in glass described in Non-Patent Document 1 has a substantially semicircular cross-sectional shape, and the bottom of the groove also has a curvature. A microchemical chip with a built-in microchannel made using a groove formed by such a known chemical etching reproduces the detection light when measuring the amount of light by photothermal conversion spectroscopic analysis (thermal lens analysis). In order to measure with good performance, there is a problem that the thermal lens must be accurately formed at the position in the width direction of the microchannel.

Patent Document 1 describes a method for suppressing isotropic etching inherent in a chemical etching method in which a groove wall surface is formed in a curved surface. In this method, the masking film when etching glass with hydrofluoric acid is masked consisting of a laminate of a chromium thin film layer and a resist thin film layer, and a small amount of chromium film moves to the glass side wall to protect the glass wall. Thus, isotropic etching is suppressed and anisotropic etching is performed.

However, the protective effect of the chromium film on the glass wall is not stable and is not sufficient to ensure anisotropy, and it is difficult to form a groove with a flat bottom surface (substantially no curvature). Met.

In order to solve the problem based on the cross-sectional shape (which is a semicircular shape) of a microchannel included in a microchemical chip obtained using a glass substrate obtained by forming a groove by the above method, the present invention It was made. That is, an object of the present invention is to provide a method for producing a grooved glass substrate having a substantially flat bottom surface by a wet etching method.

Claim 1 of this invention joins the 1st glass plate and 2nd glass plate which have a difference in the solubility with respect to an acid by melt | fusion, from the surface of the 1st glass plate with the relatively large solubility with respect to the said acid. Grooves are formed by etching with the acid until reaching the joint surface of the second glass plate.

When a masking film having a predetermined opening shape is formed on the surface of a glass plate and a groove is formed by a chemical (wet) etching method in which the exposed portion is dissolved by an acid, the isotropic dissolution action inherent to the chemical etching method The cross section of the groove is semicircular. However, in the present invention, isotropic etching is performed while etching is performed only on the first glass plate that is relatively soluble in acid (relatively high in dissolution rate by acid). As the etching progresses, the etching is simultaneously performed on glasses having different solubility in acids from the point of time when the surface of the second glass plate having relatively low solubility in acids is reached. Etching with different etch rates is performed between the glass surface, the vertical direction, and the horizontal direction.

In the process in which the etching of the first glass plate having a relatively high etching rate and the etching of the second glass plate having a relatively low etching rate proceed simultaneously, anisotropic etching is performed as an etching process for forming the entire groove. Progresses.

After the etching surface first reaches the surface of the second glass plate (fusion bonding surface), the direction parallel to the first glass surface (the portion that is relatively shallow from the glass surface and becomes the side wall of the groove) is more The etching rate is fast, and the etching rate is slow in the direction perpendicular to the first glass surface (the portion that becomes the bottom surface of the groove far from the first glass surface). As a result, apparent anisotropic etching is performed.

In the present invention, isotropic etching is performed before the etching, and apparently anisotropic etching is performed after the etching. As a result, the bottom surface portion of the groove is removed at a slower etching rate than the side wall portion, so that the bottom surface approaches a surface having a larger curvature than the side wall portion or a surface close to a flat surface (flat surface). In order to adjust the groove width (width / depth ratio) with respect to the groove depth to a larger value, the surface of the first glass plate after the etching can be adjusted by polishing.

A second aspect of the present invention is characterized in that, in the first aspect, the solubility of the first glass plate in the acid is relatively greater than that of the second glass plate due to a composition difference.

Apparently from the stage when the second glass plate is etched, the solubility of the two glass plates in the acid (acid containing hydrofluoric acid as a main component) is made different depending on the composition. An anisotropic etching mode is entered.

In a third aspect of the present invention, in the first or second aspect, a compressive stress layer is formed on a bonding surface of the second glass plate with the first glass plate and in the vicinity thereof, and the solubility of the first glass plate in the acid is the compression surface. The stress layer is more soluble in acid.

Even if the 2nd glass plate of this invention is a glass modified so that the solubility with respect to an acid may become relatively smaller than a 1st glass plate about the joint surface with a 1st glass plate or its vicinity. Good. That is, any surface may be used as long as at least one surface (surface to be joined) of the second glass plate is modified so that acid solubility is smaller than that of the first glass plate. In this case, the first glass plate and the second glass plate may have the same composition or different compositions.

As a method of modifying the glass surface to make the acid solubility in the vicinity of the surface of the second glass plate smaller than the inside thereof, and to make it less than the acid solubility of the first glass plate, an external weight is applied to the glass surface. Thus, a method for forming a layer having a small specific volume in the vicinity of the glass surface (a layer having a higher density than the inside of the glass) has been found. Such a layer is a layer having compressive strain. The reason why the etching rate of the compressive strain layer is less acid-soluble than the other portions and therefore the etching rate for the acid is slow is not clear, but is considered to be related to the high density of the glass.

In the present invention, this glass surface layer modification (decrease in acid solubility) is performed by using a polishing liquid and a polishing pad in which fine particles such as cerium oxide and aluminum oxide are suspended as polishing abrasive grains. It can be performed by moving while pressing. By this method, the surface of the second glass plate can be smoothed and a surface layer having a low etching rate can be formed on the second glass plate. In order to form a microchemical chip by bonding by fusing, the above surface modification method is advantageous because the surface of the glass plate is smoothed at the same time when fusing is performed on the entire bonding surface.

A fourth aspect of the present invention is a grooved glass substrate in which the side wall of the groove obtained by the method for manufacturing a grooved glass substrate according to any one of the first to third aspects is a curved surface and the bottom surface has a substantially flat cross-sectional shape. is there.

According to a fifth aspect of the present invention, there is provided a microchemical chip having a built-in microchannel formed by joining the grooved glass substrate according to the fourth aspect and the second glass substrate.

The microchannel built in the microchemical chip is formed by being surrounded by the groove formed on the grooved glass substrate and the bonding surface of the second glass substrate, and the bottom surface of the groove facing the bonding surface is substantially flat. Since it is (flat) and has substantially no curved surface, the light emitted from the inside of the microchannel to the outside is prevented from being refracted by the wall surface of the microchannel and changing the emitting direction. Thereby, the light intensity emitted from the microchemical chip can be accurately detected with good reproducibility.

According to the present invention, two glass plates having relatively different acid solubilities are joined to each other by fusing the glass substrate forming the groove, and the acid from the surface of the first glass plate having relatively high acid solubility. Since the groove is formed by etching until the second glass plate having a relatively low solubility is reached, isotropic etching is performed when the region to be etched is only in the first glass substrate. When both the first glass substrate and the second glass substrate are etched at the same time, the etching rate at the central portion in the width direction of the groove is greater than the side wall portion of the groove due to the difference in the etching rate between the first and second glass substrates. Get smaller. That is, the entire groove is etched anisotropically. Thereby, the groove | channel which has a cross-sectional shape with a flatter bottom part compared with the side wall part of a groove | channel can be formed with a wet etching method. By polishing the glass substrate surface after forming the groove, the aspect ratio of the groove cross section can be adjusted more greatly.

In addition, the second glass plate having a relatively low acid solubility has the same composition as the first glass plate and is formed by forming a compression strain layer on the joint surface with the first glass plate, thereby heating the second glass plate. The thermal expansion coefficients of the glass plates joined by fusion can be made the same. This prevents warping of the microchemical chip obtained by bonding.

Since the light incident on the microchannel of the microchemical chip obtained by the present invention is emitted from the flat bottom of the microchannel, the light intensity can be stably detected with good reproducibility.

The grooved glass substrate and microchemical chip according to the present invention will be described below. FIG. 1 is a schematic configuration diagram of a grooved glass substrate according to the present invention and a microchemical chip manufactured using the same. FIG. 1A is a view that serves as both a sketch of an embodiment of the grooved glass substrate 2 of the present invention and an exploded perspective view of the microchemical chip 100. FIG. 1B is a plan view of the microchemical chip 100. FIG. 1C is a cross-sectional view taken along line A-A ′ in FIG. FIG. 1D is a cross-sectional view taken along line B-B ′ in FIG.

In FIG. 1, a microchemical chip 100 of the present invention is formed with a groove 1 having a flattened bottom surface having a width of about 0.2 mm and a depth of about 0.1 mm, both ends of which are bifurcated on a joint surface 8. And a second glass substrate 4 (cover plate) bonded to the bonding surface of the grooved glass substrate 2. The second glass substrate 4 has a through-hole 3 for sample injection / discharge at a position corresponding to the groove 1 (FIG. 1A). The groove 1 constitutes the microchannel 5 of the microchemical chip 100 by bonding these two glass substrates together.

As the material of the grooved glass substrate 2 and the second glass substrate 4 constituting the microchemical chip 100, chemical durability is considered in consideration of microchemical chips used for analysis of ecological samples such as proteins, blood, and DNA and environmental analysis. Glass (having high acid resistance and alkali resistance) is preferable, and borosilicate glass, aluminoborosilicate glass, alkali-free glass, quartz glass, soda-lime silicate glass, and the like are preferable.

Next, the grooved glass substrate 2 of the present invention will be described with reference to FIG. Fig.2 (a) is a cross-sectional schematic diagram of one Example of the glass substrate with a groove | channel of this invention. In FIG. 2A, the grooved glass substrate 2 of the present invention has a glass plate 20 having a relatively high acid solubility and a glass plate 30 having a relatively low acid solubility joined by thermal fusion. Grooves 1 are formed in a predetermined shape on the non-joint surface using a photolithographic patterning method. The joining surface of the glass plate is usually smoothed by polishing using a polishing liquid containing a fine particle of cerium oxide or aluminum oxide as a polishing abrasive and a polishing pad.

The wall surface of the groove 1 includes a side wall portion 21 made of a curved surface formed by isotropic chemical etching and a bottom portion 31 having a larger curvature than the side wall portion 21 or a substantially flat surface. The glass plate 20 and the glass plate 30 can have relatively different acid solubilities by using different glass components or compositions. For example, an aluminoborosilicate glass can be used as the glass plate 20, and a quartz glass plate can be used as the glass plate 30.

A grooved glass substrate 2 shown in FIG. 2B is a schematic cross-sectional view of another embodiment of the present invention. The glass plate 20 and the glass plate 30 are made of glass having the same composition, and the glass plate 30 is pressed from the outside to the joint surface with the glass plate 20 and its vicinity (in the inner depth direction) to form the compression strain layer 301. Is. The compressive strain layer 301 is a layer in which the specific volume of glass is smaller (higher density) than the inside of the glass plate 30. The etching rate of the compressive stress layer 301 by the etching solution containing hydrofluoric acid as a main component is smaller than that of the inside of the glass and smaller than that of the first glass plate.

That is, the compressive strain layer 301 is modified so that the etching rate with respect to acid is smaller than that of the glass plate 20, and therefore, when the glass plate 20 and the glass plate 30 are simultaneously etched with acid, the etching solution is used for the entire groove 1. As an anisotropic chemical etching (etching with different etching rates depending on directions). As a result, a groove having a shape in which the bottom surface has a larger curvature than the side surface or a more flat shape can be formed by a chemical (wet) etching method. A liquid mainly containing hydrofluoric acid is used as a liquid for etching glass. A room temperature or warmed hydrofluoric acid containing liquid is used.

After forming the groove 1 of the glass substrate 2 with grooves of FIG. 2B by etching, the thickness of the glass plate 20 is reduced by polishing so that the aspect ratio is smaller (the groove width dimension is smaller than the groove depth dimension). Larger). For example, a microchannel having a cross-sectional shape with a (depth dimension / width dimension) ratio of 0.5 or less and a flat bottom portion can be obtained.

As a method of forming the compressive stress layer 301 on the surface of the glass plate 30, it is preferable to carry out simultaneously with the smoothing treatment by polishing to such an extent that the entire surface of the glass plate can be fusion bonded. For example, a polishing liquid and a polishing pad in which fine particles harder than glass such as cerium oxide or aluminum oxide are suspended as polishing abrasive grains are used and moved on the glass surface while pressing the abrasive grains against the glass surface.

The compressive stress layer formed by moving the abrasive grains of cerium oxide while pressing them against the glass surface is, for example, a polishing liquid in which abrasive grains having an average particle size D50 of 0.4 to 1.4 μm are suspended on the glass surface. It can be formed by supplying and moving the abrasive grains while pressing them against the glass surface with a pressure of several tens gf / cm ² or more with a polishing pad made of urethane or the like. The glass surface can be smoothed by polishing and a compressive stress layer can be formed simultaneously. In addition, fine particles of colloidal silica can be used as the abrasive grains. The magnitude of the strain of the compressive stress layer and the depth from the glass surface are determined by adjusting the type and size of the abrasive grains used, the polishing pressure (the magnitude of the force applied from the outside), and the like. For the formation of the compressive stress layer, a known, for example, Oscar double-side polishing apparatus can be used. Moreover, a compressive stress layer can be formed by pushing a sharp metal needle into the glass surface without a gap.

Next, the groove formation of the grooved glass substrate 2 according to the present invention and the microchemical chip manufacturing method using the substrate will be described. FIG. 2 is a view for explaining a method for producing a grooved glass substrate and a microchemical chip according to the present invention. The cover plate is cut into a predetermined shape, and a through hole 3 serving as an injection hole and a discharge hole is drilled at a predetermined position of the glass plate 6 whose end face is chamfered (step shown in FIG. 3A).

Sputtering a metal masking film 11 made of a laminated film of a chromium film and a gold film on the surface of a glass plate 7 (a fusion bonded body of a first glass plate and a second glass plate) serving as a base plate (a glass substrate 2 with a groove). A thin film forming method is used for coating, and a photoresist layer 12 is further applied. The portion of the photoresist layer that is not masked by the masking pattern 13 is altered, dissolved, and removed by irradiation with ultraviolet light, and the exposed metal masking film is removed with an aqueous solution of ceric ammonium nitrate. The exposed surface of the base glass is etched with an acid-based etchant containing hydrofluoric acid. Etching can be performed using, for example, 49% hydrofluoric acid with heating or room temperature and an etching time of about 2 to 5 minutes. Thus, the grooved glass substrate 2 having the grooves formed on the glass surface is produced (FIG. 3B).

To fuse and bond the grooved glass substrate 2 and the second glass substrate, a pair of glass substrates are aligned and stacked, for example, placed on an alumina base having a smooth surface, An alumina weight plate having a smooth surface is placed as a weight. Thus, the joining surface is placed in an electric furnace in a state of being pressed from the outside, and is heated to a predetermined temperature and fusion-bonded. After slow cooling, the glass substrate assembly is taken out. The heating temperature is a temperature near or above the softening point of the glass. A plurality of glass joined bodies may be fusion-bonded simultaneously by interposing an alumina weighted body between a plurality of sets of glass substrates. The base plate and the cover plate are joined by fusion to obtain a microchemical chip in which the injection hole, the microchannel, and the discharge hole communicate with each other (step of FIG. 3C).

By injecting a sample solution from the through-hole 3 into the microchannel 5 of the microchemical chip 100, and using known analysis methods such as electrophoresis, photothermal conversion spectroscopic analysis (thermal lens analysis), and fluorescence analysis, Qualitative analysis, quantitative analysis, mixing, reaction, extraction, separation, etc. of the sample in the liquid are performed in the microchannel.

Next, advantages of carrying out photothermal conversion spectroscopic analysis using the microchemical chip of the present invention will be described. FIG. 4 is a schematic configuration diagram of the photothermal conversion spectroscopic analysis system. The photothermal conversion spectroscopic analysis system receives an irradiation unit 101 that irradiates excitation light and detection light to a sample in liquid in the microchannel 5 of the microchemical chip 100, and detection light that has passed through the microchannel 5 of the microchemical chip. And the light receiving unit 102.

The irradiation unit 101 includes an excitation light source 105 that outputs excitation light for forming a thermal lens in a sample solution, an acoustooptic element 107 that modulates excitation light output from the excitation light source 105, and an acoustooptic element. A prism 111 that separates excitation light diffracted by black diffraction by 107 into zero-order light and primary light, a detection light source 106 that outputs detection light, an objective lens 130, primary light from the prism 111, and The dichroic mirror 108 irradiates the detection light from the detection light source 106 coaxially through the objective lens 130 to the micro flow channel 5 of the microchemical chip 100.

The light receiving unit 102 shields the excitation light that has passed through the microchannel 5 of the microchemical chip 100 and selectively filters only the detection light, and the photoelectric converter 401 that detects the filtered detection light. And a lock-in amplifier 404 for synchronizing the signal from the photoelectric converter 401 with the acousto-optic modulator 107, and a computer 405 for analyzing the data of this signal. In order to selectively transmit only part of the detection light, a pinhole is disposed between the microchemical chip 100 and the photoelectric converter 401.

Excitation light emitted from the excitation light source 105 enters the objective lens 130 via the acousto-optic modulator 107, the prism 111, and the dichroic mirror 108. On the other hand, the detection light emitted from the light source for detection light 106 enters the objective lens 130 via the dichroic mirror 108.

The excitation light and detection light incident on the objective lens 130 are perpendicularly incident on the microchemical chip 100 so as to be focused on the sample flowing in the microchannel 5 built in the microchemical chip 100.

The detection light that is refracted and transmitted through the thermal lens in the sample generated by the irradiated excitation light is selectively transmitted by the wavelength filter 403 and then converted into an electrical signal by the photoelectric converter 401. The detection light converted into the electric signal is synchronized with the acousto-optic modulator 107 by the lock-in amplifier 404 and analyzed by the computer 405 to perform photothermal conversion spectroscopic analysis.

Therefore, the incident side wall surface and the output side wall surface (bottom part of the groove formed in the grooved glass substrate) of the microchannel 5 through which the excitation light and the detection light of the microchemical chip 100 pass are such that incident light is not scattered. It is important that it is smooth and does not change due to refraction from the incident direction on the wall surface of the microchannel.

When setting the microchemical chip 100 in the photothermal conversion spectroscopic analysis system of FIG. 4, it is important to set the microchemical chip so that excitation light and detection light are incident on the center of the microchannel in the width direction. That is, in order to accurately measure the intensity of the detection light with high reproducibility, it is important to increase the positioning accuracy of the microchemical chip. This is because the intensity of the detection light is affected by the displacement of the microchemical chip.

FIG. 5 is a diagram for explaining the dependence of the intensity of the detection light on the width direction of the microchannel. Since the bottom of the microchannel cross-sectional shape of the microchemical chip of the present invention is flattened, the dependence of the intensity of emitted light on the position in the width direction of the microchannel is as shown in FIG. It has a trapezoidal or rectangular shape (intensity distribution approximated to a trapezoid or a rectangle) in the width direction, and the distance in the width direction in which the light intensity has a substantially constant value (maximum level value) is long. That is, it can be seen that the variation tolerance of the set position on the chip stage in the photothermal conversion spectroscopic analysis system of the microchemical chip is large. As a result, the intensity of the detection light can be measured stably and with good reproducibility.

FIG. 6 shows a cross-sectional shape of a groove formed by the conventional technique. The cross-sectional shape of the groove 1 formed on the surface of the glass substrate 2 with a groove has a semicircular curved surface 21. Both the side wall and bottom of the groove are curved. This is because chemical etching (wet etching) on a homogeneous medium depends on an inherent property that isotropic etching.

Since the bottom surface of the microchannel of the microchemical chip manufactured by the conventional technique shown in FIG. 6 has a curvature, the dependence of the intensity of the emitted light on the position in the width direction of the microchannel is shown in FIG. As shown in (b), it is indicated by a substantially parabolic curve, and the light intensity can only be obtained at a narrow portion at the center in the channel width direction. That is, in such a microchemical chip, the intensity of detection light is greatly influenced by the setting position of the microchemical chip, and it is necessary to strictly control the positioning accuracy.
The present invention will be described below with reference to examples and comparative examples.

A quartz glass plate was used as the second glass plate that has a relatively low acid solubility (relatively low etching rate) constituting the grooved glass substrate. A quartz glass plate (thickness: 1.1 mm) having a length of 70 mm and a width of 30 mm was lapped (ground) with 20 alumina abrasive grains to a thickness of about 0.75 mm. The glass plate after lapping was polished. Polishing is performed using a polishing solution obtained by suspending free abrasive grains of cerium oxide having an average grain size D50 of 0.8 μm in water and a polishing pad LP66 made by Rhodes, with a thickness of 0.71 mm (on one side of the machining allowance). Polishing until 20 μm).

On the other hand, a borosilicate glass Pyrex (registered trademark) glass was used as the first glass plate constituting the grooved glass substrate and having relatively high acid solubility. A Pyrex (registered trademark) glass plate (thickness: 1.1 mm) 70 mm long and 30 mm wide was lapped (ground) with 20 alumina abrasive grains to a thickness of about 0.71 mm. Using a polishing solution in which loose abrasive grains having an average grain size D50 of 0.8 μm are suspended in water and a polishing pad LP66 made by Rhodes, the thickness is 0.70 mm by a double-side polishing apparatus. Polished until

Two glass plates smoothed by polishing are superposed and placed on an alumina sintered ceramic base whose surface is polished, and in an electric furnace, at a temperature higher than the softening point of Pyrex (registered trademark) glass and from the softening point of quartz glass The glass plate was fusion bonded by heating to a low temperature to produce a glass plate bonded body.

Next, the glass plate bonded body is cleaned, and a laminated film of a chromium film and a gold film is coated on the surface of the first glass plate by a sputtering thin film forming method, patterned into a predetermined shape, and a masking film (opening width 10 μm) did. Etch exposed portion of glass using 49% hydrofluoric acid at room temperature as etchant, etch first glass plate and second glass plate, and wet chemistry groove with depth of 0.17mm and width of about 0.3mm Grooves were formed in the etching. The etching rate of this glass with hydrofluoric acid was 10 μm / min, and the etching rate of quartz glass with hydrofluoric acid was about 8.3 times. When the cross-sectional shape of the groove was observed with a scanning electron microscope, the cross-sectional shape had a flat bottom surface.

The first glass plate was produced in the same manner as in Example 1, and the second glass plate having a compressive strain layer formed on the first glass surface was used. In order to form a large compressive strain layer on the glass surface, the surface of the glass was pressure polished with a coarser abrasive grain under a larger pressure. A double-side polishing apparatus using a polishing solution in which free abrasive grains of cerium oxide having an average particle size D50 of 1.4 μm are suspended in water and a polishing pad LP66 made by Rhodes, at a polishing pressure of 100 gf / cm ^2. Was polished until the thickness became 0.71 mm (20 μm on one side of the machining allowance).

A glass plate bonded body was produced in the same manner as in Example 1, and grooves were formed on the surface of the first glass plate by etching with a 49% hydrofluoric acid solution to obtain a sample of a glass substrate with grooves. The groove had a depth of about 0.10 mm and a width of about 0.2 mm. When the cross-sectional shape of the groove was observed with a scanning electron microscope, the cross-sectional shape had a flat bottom surface.

Comparative Example A grooved glass substrate made only of the first glass plate was produced. That is, grooves were formed on the surface of the first glass plate by etching using hydrofluoric acid as an etchant. The cross-sectional shape of the formed groove was a semicircular curved surface as shown in FIG. 6, and (maximum depth) :( maximum width) was about 1: 2.

When glass compositions having different compositions are used in Example 1, the difference in etching rate between the two glasses is preferably 5 times or more, and more preferably 8 times or more.
That is, it is preferable to select a set of glass plates so that the etching rate of the first glass plate with respect to hydrofluoric acid is at least five times higher than the etching rate of the second glass plate with respect to hydrofluoric acid.

The compressive stress layer formed on the surface of the second glass plate and in the vicinity thereof is not only simultaneously with the smoothing of the glass surface using the abrasive grains shown in the above-mentioned embodiment, but also a sharp needle-like hard metal piece or It can be formed by pressing the diamond indenter against the glass surface without a gap. By making the composition of the 2nd glass plate which forms a compressive-stress layer the same as the composition of a 1st glass plate, since the expansion coefficient of a glass plate becomes the same, the advantage that a curvature does not arise arises.

By the method of the present invention, a groove having a shape with a flattened bottom can be formed by a chemical etching method. This grooved glass substrate is used in the manufacture of microchemical chips.

FIG. 1 is a diagram for explaining a grooved glass substrate and a microchemical chip according to the present invention. FIG. 2 is a schematic cross-sectional view of the grooved glass substrate of the present invention. FIG. 3 is a diagram for explaining a method for producing a grooved glass substrate according to the present invention. FIG. 4 is a schematic configuration diagram of the photothermal conversion spectroscopic analysis system. FIG. 5 is a diagram for explaining the dependency of the intensity of the detection light on the direction of the microchannel width. FIG. 6 is a diagram for explaining a cross-sectional shape of a groove obtained by chemical (wet) etching according to the prior art.

Explanation of symbols

1: Groove 2: Glass substrate with groove (base plate)
3: Through hole (injection hole, discharge hole)
4: Second glass substrate (cover plate)
5: Micro flow path 6, 7: Glass plate 8: Bonding surface (bonding surface)
11: Laminated film of chromium and gold 12: Photoresist layer 13: Masking pattern 20: First glass plate 21 having relatively high acid solubility 21: Groove sidewall 30: Second glass plate having relatively low acid solubility 31: groove bottom 100: microchemical chip 101: irradiation unit 102: light receiving unit 301: compression stress layer

Claims (5)

The first glass plate and the second glass plate having a difference in solubility with respect to the acid are joined by fusion bonding, and the second glass plate is joined from the surface of the first glass plate having a relatively high solubility with respect to the acid. Grooves are formed by etching with the acid until reaching the surface. A method for producing a glass substrate with grooves. The method for producing a grooved glass substrate according to claim 1, wherein the solubility of the first glass plate in the acid is relatively greater than that of the second glass plate due to a composition difference. A compressive stress layer is formed on and near the joint surface of the second glass plate with the first glass plate, and the solubility of the first glass plate in the acid is greater than the solubility of the compressive stress layer in the acid. The manufacturing method of the glass substrate with a groove | channel of Claim 1 or 2. The glass substrate with a groove | channel which has a groove | channel where the side wall part obtained by the manufacturing method of the glass substrate with a groove | channel in any one of Claims 1-3 is a curved surface, and a bottom face part is a substantially flat surface. A microchemical chip having a built-in microchannel formed by joining the grooved glass substrate according to claim 4 and a second glass substrate.

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