JP2004256380A - Method of joining glass substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the formation of bubbles at the joining part of glass substrates to solve a problem that the bubbles damage the appearance of the product and lowers the joining strength. <P>SOLUTION: In a method of joining a plurality of glass substrates, the glass substrates are stacked and heated under a pressure applied in the thickness direction of the glass substrates. Before joining the glass substrates, a dummy groove other than a channel groove to flow a fluid is formed on the joining surface of at least one glass substrate, and through-holes communicating with the dummy groove and opening to the atmosphere are formed. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for joining glass substrates, and more particularly, to a method for joining quartz glass substrates.
[0002]
[Prior art]
Glass and quartz glass are not only excellent in chemical resistance and heat resistance but also extremely stable physicochemical containers, and have been widely used as jig materials for processing tanks for semiconductor manufacturing equipment. Recently, in the fields of chemistry and biotechnology, glass members and quartz glass members having a fine three-dimensional structure, such as microchips and microchemical plants, have attracted attention for the purpose of integrating chemical reactions.
[0003]
When bonding such a glass or quartz glass, if a bonding material such as an adhesive or low-melting glass is interposed, chemical resistance or heat resistance may be impaired. It is desirable to perform heat fusion that can completely integrate itself (for example, see Patent Document 1).
[0004]
[Patent Document 1] JP-A-6-298538 (pages 2 to 5)
[0005]
[Problems to be solved by the invention]
FIG. 2 shows a structural example of a microchemical plant chip. In this microchemical plant chip, a front substrate 17 having a through-hole formed of an inlet A11 for two chemicals, an inlet B12 and one outlet 13 and a flow channel 15 serving as a flow path for a chemical are formed. And the rear substrate 18 thus bonded.
[0006]
Individual chemicals to be reacted are injected from the injection port A11 and the injection port B12, and the two chemicals are mixed at the junction of the grooves 15 serving as flow paths.
[0007]
The reaction time of the two chemicals is controlled by the flow path length of the groove 15 and the flow rate of the chemicals after the confluence, and the chemicals after the reaction are taken out from the outlet 13.
[0008]
In the case of such a microchemical plant chip, there is a problem that large bubbles are likely to be generated in a portion where a flow path is not formed in a relatively large area as shown in a bubble remaining portion 19 in FIG.
[0009]
FIGS. 4 (a) to 4 (e) are illustrations of the mechanism of the above-mentioned residual foam. In the process of raising the temperature of the glass substrate shown in FIG. 4A, the superimposed front substrate 17 and rear substrate 18 have a non-uniform temperature distribution in the glass substrate such that the temperature rises outside the glass substrate before the inside. Due to the warpage of the glass substrate due to the concaved adhesive surface, bubbles 20A are generated between the front substrate 17 and the rear substrate 18.
[0010]
While keeping the high temperature, as shown in FIGS. 4B to 4D, the warpage of the substrate is reduced as the entire glass substrate is soaked, and the outer circumferences of the front substrate 17 and the rear substrate 18 are reduced. Although the bonding proceeds from the portion, the bubble 20D remains between the front substrate 17 and the rear substrate 18 because there is no escape route.
[0011]
When such an unjoined portion (bubble remaining portion) occurs, there is a problem that not only the appearance of the product is impaired, but also the joining strength is reduced. Particularly when a chemical solution is injected at a high pressure as in a microchemical plant chip, the reliability of the bonding strength becomes a problem.
[0012]
[Means for Solving the Problems]
The present inventors have studied the fusion of glass substrates, and as a result, have come to invent a bonding method that does not leave bubbles between the glass substrates when the glass substrates are fused.
[0013]
According to the first aspect of the present invention, in a bonding method in which a plurality of glass substrates are stacked and heated while applying pressure in a thickness direction of the plurality of glass substrates to bond the plurality of glass substrates, Prior to doing so, a dummy groove is formed separately from the flow path groove for flowing a fluid on at least one of the glass substrate bonding surfaces, and the through hole is formed to be connected to the dummy groove and communicate with the atmosphere. This is a method for bonding glass substrates to be bonded.
[0014]
According to the invention of claim 2, the position of the first glass substrate in which the through hole for injecting the liquid and the through hole for injecting the liquid are formed, and the position of the second glass substrate in which the flow channel for flowing the liquid is formed. In the joining method of joining and bonding the first glass substrate and the second glass substrate by heating while applying pressure in the thickness direction, the joining surface of the second glass substrate is parallel to the flow channel. The first glass substrate is connected to the dummy groove, and a through hole communicating with the atmosphere is formed together with a through hole for injecting and discharging a fluid. A method for joining glass substrates, comprising joining two glass substrates.
[0015]
According to a third aspect of the present invention, there is provided the method for bonding glass substrates, wherein the glass substrate is quartz glass.
[0016]
According to a fourth aspect of the present invention, there is provided a method of bonding glass substrates, wherein, when heating, the glass substrates to be bonded are bonded in a gas atmosphere having a molecular size smaller than that of air (oxygen, nitrogen) molecules. is there.
[0017]
According to a fifth aspect of the present invention, there is provided a method for bonding glass substrates, wherein when bonding the glass substrates, at least a bonding surface of the glass substrates is wetted with water.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
[Example 1]
FIG. 1 is a diagram illustrating a manufacturing procedure of a microchemical plant chip according to the first embodiment of the present invention.
[0019]
First, as shown in FIG. 1, a front substrate 17 and a rear substrate 18 each made of quartz glass of 100 mm square and 2 mm thick are prepared, and the front substrate 17 is formed with a hole having a diameter of 2 mm penetrating in the thickness direction of the substrate. A certain injection port A11, an injection port B12, a spout 13 and a dummy through hole 14 are formed by a sand blast method or a diamond drill.
[0020]
A flow channel 15 communicating with the two inlets and one spout and a dummy groove 16 communicating with the dummy through hole are formed on the joint surface of the rear substrate 18 at a depth of 500 μm and a width of 500 μm, respectively. Form. The dummy groove 16 is formed in a region on the substrate where bubbles are likely to remain, and is desirably formed in the same step as the formation of the flow channel. Specifically, a substrate portion where the flow channel groove 15 and the dummy groove 16 are not formed is covered with a resistant resist, and is formed by a subtractive method. As the subtractive method, a sand blast method or a chemical etching method using hydrofluoric acid is used.
[0021]
Note that the dummy through holes 14 may be formed in the rear substrate 18.
It is more preferable that the dummy groove has a closed groove pattern as shown in FIG. 1 because the adhesive strength is increased.
[0022]
The pitch of the dummy grooves 16 is preferably 0.5 to 2 mm from the viewpoint of the bonding strength and the bubble remaining property.
[0023]
Next, the joining surface between the front substrate 17 and the rear substrate 18 to be joined is finished to a surface accuracy of about several μm by polishing. This polishing may be performed before the hole processing and the groove processing.
[0024]
After completion of the polishing, at least the entire bonding surface is washed with a 10% hydrofluoric acid solution.
[0025]
After the hydrofluoric acid solution is sufficiently rinsed with pure water, the front substrate 17 and the rear substrate 18 are overlapped while being aligned with each other in a state where sufficient moisture remains, and pressed so that the bonding surfaces are in close contact with each other. In this step, the bonding surface may be once dried and then the bonding surface may be wetted again, or the alignment is performed by immersing the front substrate 17 and the rear substrate 18 in pure water. Adhering the surfaces is more preferable because no foreign matter remains on the joint surface.
[0026]
The front substrate 17 and the rear substrate 18 having the bonding surfaces adhered to each other are fixed to a jig for applying a pressure of 100 to 300 g per square centimeter to maintain the bonding state of the bonding surfaces.
[0027]
The front substrate 17 and the rear substrate 18 which are fixed to the jig are heated in an oven in an air atmosphere at a heating rate of 10 to 50 ° C./min before the moisture existing at the interface between the bonded bonding surfaces is evaporated. And heating at 1500 ° C. for 2 hours. Since bubbles (gas) generated on the substrate bonding surface in the pressurizing and heating steps are discharged out of the substrate through the dummy grooves 16 and the dummy through holes 14, it is possible to prevent bubbles from remaining on the substrate bonding surface. .
[0028]
Note that, when bonding is performed in a helium atmosphere or a hydrogen atmosphere, since the molecular size of the gas is smaller than that of oxygen or nitrogen in air, remaining bubbles can be further reduced.
[0029]
FIG. 1 (b) shows a completed state of the microchemical plant chip thus joined. The microchemical plant chip thus formed has an advantage that the number of steps is not increased because the dummy groove and the flow path groove can be formed at the same time, and the injection port, the spout and the dummy through hole can be formed at the same time.
[0030]
In the first embodiment, quartz glass has been described. However, the glass substrate may be made of a glass material such as soda lime glass or registered trademark Pyrex glass. The temperature is set higher than the transition point of the glass material used and lower than the softening point.
[0031]
[Example 2]
FIG. 3 shows an example of forming a microchemical plant chip according to the second embodiment, which is different from the first embodiment in that a flow channel 27 is formed up to the end face of the front substrate, and the liquid inlet A24, the inlet B25, It differs in that a spout 26 is provided. In the structure according to the second embodiment, it is possible to arrange the microchemical plant chip upright with the inlet A24 and the inlet B25 facing upward, and the installation area of the microchemical plant chip is larger than in the first embodiment. Can be reduced.
[0032]
In the first and second embodiments, an example of application to a microchemical plant chip has been described. However, various patterns of flow channels are selected, and dummy grooves and through holes are provided in regions where flow channels are not formed. Can be applied to the formation of a chip formed by bonding a glass substrate such as a biochip. In each of the first and second embodiments, the dummy groove and the through hole are each one, but a plurality of dummy grooves and through holes may be provided.
[0033]
5 (a) to 5 (e) show process diagrams of the above-described substrate bonding method in which no bubble remains.
[0034]
Referring to this figure, the mechanism in which no bubble remains will be described. First, in the heating process shown in FIG. 5A, as shown in FIG. A bubble 23A is generated between the front substrate 17 and the rear substrate 18 due to the unevenness of the temperature distribution in the glass substrate such that the temperature rises before the inside of the glass substrate and the inside of the glass substrate causes the bonding surface to be concave. I do.
[0035]
FIGS. 5B to 5D show the movement of the bubbles 23B, 23C, and 23D when keeping the temperature at a high temperature. When the glass substrate is kept at a high temperature, the warpage of the substrate is reduced as the entire glass substrate is soaked, the bonding proceeds from the outer peripheral portions of the front substrate 17 and the rear substrate 18, and the gas in the bubbles flows into the dummy grooves. Since the bubbles gradually escape from the dummy through-holes 14 through the holes 16, the front substrate 17 and the rear substrate 18 are joined together without any remaining bubbles as shown in FIG. .
[0036]
【The invention's effect】
As described in detail above, the present invention provides, when bonding glass substrates, a dummy groove and a through-hole connected to the dummy groove, in addition to a flow channel groove for a fluid such as a chemical solution, so that a glass substrate bonding surface is provided. This can suppress the generation of residual bubbles in the glass, so that the bonding strength between the glass substrates can be increased, and the reliability of the bonding between the glass substrates can be increased.
[Brief description of the drawings]
FIG. 1 is a diagram showing a manufacturing procedure of a microchemical plant chip according to a first embodiment of the present invention.
FIG. 2 is a diagram showing a structural example of a microchemical plant chip.
FIG. 3 is a diagram showing an example of forming a microchemical plant chip according to a second embodiment of the present invention.
FIG. 4 is an explanatory view of a mechanism in which bubbles remain when bonding substrates.
FIG. 5 is an explanatory diagram of a mechanism that does not cause a bubble to remain when bonding substrates.
[Explanation of symbols]
11 Inlet A
12 Inlet B
13 Injection port 14 Dummy through hole 15 Flow path groove 16 Dummy groove 17 Front substrate 18 Back substrate 19 Bubbles remaining portions 20A, 20B, 20C, 20D Bubbles 23A, 23B, 23C, 23D Bubbles 24 Inlet A
25 Inlet B
26 Outlet 27 Flow channel

Claims (5)

In a bonding method of stacking a plurality of glass substrates, heating while applying pressure in the thickness direction of the plurality of glass substrates, and bonding the plurality of glass substrates,
Prior to bonding the glass substrates, a dummy groove is formed separately from a flow channel for flowing a fluid on at least one of the glass substrate bonding surfaces, and a through hole that connects to the dummy groove and communicates with the air is formed. A method of bonding glass substrates, comprising: A first glass substrate having a through hole for injecting a liquid and a through hole for discharging a liquid is aligned with a second glass substrate having a channel groove for flowing the liquid, and the thickness direction. In the joining method of joining the first glass substrate and the second glass substrate by heating while applying pressure to the first glass substrate,
On the bonding surface of the second glass substrate, a dummy groove parallel to the flow channel is formed together with the flow channel, and the first glass substrate is connected to the dummy groove and communicates with the atmosphere. A method for bonding glass substrates, comprising: forming a through hole together with the through hole for injecting and discharging a fluid; and bonding the first and second glass substrates. The method for bonding glass substrates according to claim 1, wherein the glass substrate is quartz glass. 4. The method according to claim 1, wherein when the heating is performed, the glass substrates to be bonded are bonded in a gas atmosphere having a molecular size smaller than that of air (oxygen, nitrogen) molecules. 5. Glass substrate bonding method. The method for bonding glass substrates according to claim 1, wherein when the glass substrates are overlapped, at least a bonding surface of the glass substrates is wetted with water.

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