JP2003054971A - Method for bonding quartz glass - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform bonding of quartz glass parts at a comparatively low temperature and with high quality. SOLUTION: Joints of the quartz glass parts are closely adhered in a wet state with water and are heated at a temperature being higher than a transition point of the quartz glass and being lower than a softening point thereof in a state where prescribed pressure is applied to the closely adhered part before water at a joint interface dries.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for processing a quartz material, and more particularly to a method for joining a plurality of quartz glass parts by heating.

[0002]

2. Description of the Related Art Quartz processed products have high heat resistance, are less likely to cause precipitation of impurities, have a low expansion coefficient, are hard, and have good ultraviolet to visible light transmission properties. Jigs for high temperature processes and substrates for thin film semiconductor devices,
It is used for optical parts.

Here, in particular, jigs and optical parts are often required to have complicated shapes and precise processing. But,
On the contrary, the high heat resistance and hardness described above are obstacles in processing.

Generally, when manufacturing a complicated shape, the shape is processed or a plurality of parts are formed by cutting out from the material of Muku or applying a temperature higher than the softening point to the material to soften it. We are also joining.

However, the shaving from a solid material causes a problem in terms of cost, because it requires a very long time for processing, and many materials are wasted as shavings. On the other hand, in the method of heating above the softening point, for example, when it is desired to perform uniform bonding while maintaining surface accuracy on a flat surface of a large area, the parts soften,
The surface accuracy is lowered, and air bubbles are mixed in the joint portion, which causes quality problems such as a decrease in dimensional accuracy and optical accuracy.

As a method for solving these problems, a method disclosed in Japanese Patent Laid-Open No. 6-298539 is known. In this method, when the quartz glass materials are bonded to each other, the bonding surfaces are polished and mirror-finished, washed with cleaning water, and the bonding surfaces are brought into close contact with each other while being wet with the cleaning water.
The method includes the steps of drying at a temperature of 90 ° C., preheating at a temperature of 100 to 150 ° C., and then heat-treating at a temperature of 400 ° C. or higher. The characteristic of this method is that the components and impurities contained in the washing water and the attached chemicals form a thin adhesive film on the adhesive surface that acts as an adhesion medium through the steps of drying and preheating, and the quartz glass material is bonded through this adhesive film. It is to bond each other.

According to this method, by heating at a relatively low temperature of 1000 ° C. or less, it is possible to obtain a material having a relatively high transparency even at the joint portion.

[0008]

However, the above-mentioned Japanese Unexamined Patent Publication (Kokai) No.
In the method shown in Japanese Patent No. 298539, the mirror polishing accuracy is about 100 Å for forming a thin adhesive film on the joint surface, and the waviness of the surface is about 0.5 μm.
High polishing accuracy is required, and the cost in this process becomes a problem. In addition, this method is merely adhesion by an adhesive film, and the two parts are not completely fused at the joint portion, so that the optical characteristics are deteriorated at the interface portion,
Further, there is a problem that cracks may occur when this part is heated for additional processing.

An object of the present invention is to perform a polishing process with a relatively low precision, and even if the heating temperature is a relatively low temperature, complete fusion occurs at the bonded portion, and a sufficient bonding accuracy and strength can be obtained even after the bonding. To provide a method.

[0010]

According to the method of joining quartz glass of the present invention, the first step of polishing the joint surfaces of the respective quartz glass parts and further chemically cleaning the quartz glass parts, and the respective quartz glass cleaned as described above. Wetting the joint surfaces of the parts with water and bringing the joint surfaces into close contact with each other; a third step of applying a predetermined pressure to the portion where the joint surfaces are brought into close contact with each other; Before the water between them dries,
The bonding surface contact portion in a state where the predetermined pressure is applied is heated at a temperature higher than the transition point and lower than the softening point of the quartz glass material, and the heating is continued for a predetermined time to thereby bond the bonding surface contact portion. And a fourth step of joining a plurality of quartz glass parts.

According to the method for joining quartz glass of the present invention,
At a relatively low temperature below the softening point, a bonded portion having sufficient strength can be obtained, and the polishing accuracy of the bonded surface may be relatively rough, about several μm.

Although the principle of the present invention has not been elucidated accurately, it is generally known that the transition temperature of the quartz material decreases as the content of OH groups increases, and from this fact, it is known that the bonding of the materials adheres closely to each other. When water is present at the interface between the surfaces, heating while applying a constant pressure causes the OH groups generated from water to enter the bonding surface, and the OH group content near the interface increases, so the transition point temperature decreases, It is thought that this is due to the progress of fusion.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [Embodiment 1] FIG. 1 shows a procedure flow of a method for joining quartz glass parts according to Embodiment 1 of the present invention. Specifically, the joining was performed as follows. (1) Polishing the bonding surface of each quartz component to be bonded to several μm
The surface accuracy is to some degree. (2) Next, at least the entire bonding surface is cleaned with 10% hydrofluoric acid. (3) After thoroughly washing out this hydrofluoric acid with pure water,
With sufficient water remaining, align the parts to be joined and press them so that the joint surfaces are in close contact. In this step, the bonding surface may be dried once, and then the bonding surface may be wetted again with water so that the bonding is performed. (4) In order to maintain a close contact state of the joint surfaces while applying a predetermined amount of pressure to a plurality of (for example, two) parts in which the joint surfaces are in close contact with each other in the next heating step ((5)). Fix it to the jig. The pressure at this time is 100 to 300 g per square centimeter. (5) While the moisture existing at the interface between the closely bonded joint surfaces is not dried, the component fixed to the jig is heated at 1500 ° C. for 2 hours in an oven in a nitrogen atmosphere.

As a sample, the surface was polished to a surface accuracy of 3
Two quartz glass plates each having a size of 50 μm or less and having a thickness of 5 mm and having a size of 50 μm or less were joined by the above-described flow to prepare a quartz glass plate having a size of 50 mm square and a thickness of 10 mm. Further, as Comparative Example 1, a quartz glass plate having the same dimensions, which was polished to the same surface accuracy, was adhered in a non-wetting state by sufficiently drying the surface in the step (3) of the above flow. Bonding was carried out in exactly the same steps as in the example, and similarly, a 50 mm square and 10 mm thick one was prepared. In the sample of this example,
When the side surfaces are polished after joining, the joints are invisible to the naked eye even when viewed from the side, but in the sample of Comparative Example 1, the joint surfaces are slightly visible even after polishing. Further, when laser light is incident from the surface, in the sample of the present example, the spread of light is not visible even when observed from the side surface, but in Comparative Example 1, the light is diffused at the bonding surface when observed from the side surface. It was observed.

When these two samples were heated above the softening point and tried to be bent, the samples of this example could be processed without problems, but the samples of Comparative Example 1 A crack occurred.

From these facts, it can be seen that in the case where the joining method of the present invention is applied, the joining surfaces are completely fused and no interface remains.

[Embodiment 2] FIG. 2 is an improvement of the step (3) in the flow of Embodiment 1 (FIG. 1). Example 1
In the above, the wet joint surface was brought into close contact with the air, but in this method, dust floating in the air is easily attached to the wet surface. Therefore, dust is mixed into the joint portion as a foreign matter to form bubbles, remain as a foreign matter, or, in the worst case, cause cracking.

Therefore, the bonding surface is brought into close contact with pure water containing few particles to prevent dust floating in the air from adhering to the bonding surface.

In the case of Example 1, some foreign matter was found to be mixed in a 50 mm square, but in this Example, no foreign matter was found.

The contacting work may be carried out either in a water tank containing pure water or in running water.

[Embodiment 3] FIG. 3 is a flow chart of a joining process, which is common to the first and second embodiments, in which a step of applying ultrasonic vibration to the joining surface is adopted in the heating step of the step (5). is there.

The ultrasonic vibration was applied by fixing a jig for fixing the components under pressure on the stage having a structure for transmitting the vibration from the vibrator through the heat insulating structure. If this step is adopted, the movement of molecules at the interface of the joint becomes active, so that the fusion proceeds more smoothly.

[Fourth Embodiment] In the first and second embodiments, the pressure is applied by fixing the component to the jig in a state where the components are in close contact with each other. However, depending on the shape of the component, the alignment is completed. When fixing to a jig with, there arises a problem that a position shift occurs. In the present embodiment, in order to solve this problem, after the alignment is completed, the periphery of the joint surface is temporarily fixed with an ultraviolet curable resin and then fixed to a jig. In this method, the resin sublimes at about 400 ° C., which is much lower than the transition temperature of quartz, so that the joint surface is kept clean. Therefore, it is particularly effective for joining parts having complicated shapes.

In the above Examples 1 to 4, nitrogen was used as the atmosphere during heating, but the atmosphere may be other inert gas such as argon, reducing gas such as hydrogen, vacuum state, atmosphere. , Etc. are possible. Among these, reducing gas, inert gas, and vacuum are particularly preferable.

[0025]

EFFECTS OF THE INVENTION According to the present invention, the bonding of a plurality of quartz glass components is completely fused at the interface of the bonded portion even though the heating is performed at a relatively low temperature, and therefore the optical and mechanical strength is high. It can be done with quality. Moreover, since the heating temperature is equal to or lower than the softening point, deformation of each component can be suppressed.

[Brief description of drawings]

FIG. 1 is a process flow of Example 1

FIG. 2 is a process flow of Example 2

FIG. 3 is a process flow of Example 3

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor, Teru Azumi             621 Uhara, Yamazaki-cho, Shishiwa-gun, Hyogo Prefecture             In Suf Electronics F-term (reference) 4G061 AA02 BA05 BA12 CA02 CB07                       CB12 CC01 DA05 DA06 DA09                       DA13 DA15 DA23 DA42 DA67

Claims (5)

[Claims] 1. A method of joining a plurality of quartz glass parts, which comprises a first step of polishing the joining surfaces of the respective quartz glass parts and further chemically cleaning them, and the cleaned quartz glass parts. The second step of wetting the joining surfaces of with water, and bringing the joining surfaces into close contact with each other, a third step of applying a predetermined pressure to the portion where the joining surfaces have been brought into close contact with each other, While the intervening water is not dried, the joint surface adhesion portion in the state where the predetermined pressure is applied is heated at a temperature higher than the transition point and lower than the softening point of the quartz glass material, and the heating is performed for a predetermined time. A fourth step of continuing the step of joining the plurality of quartz glass parts in the joint surface contact portion by continuing the fourth step. 2. The method of joining quartz glass according to claim 1, wherein in the second step, the joining surfaces are brought into close contact with each other in water in a stationary state or a flowing state. 3. The pressure applied in the third step is
The method for joining quartz glass according to claim 1 or 2, wherein the range is 100 g / cm 2 to 300 g / cm 2. 4. The method of bonding quartz glass according to claim 1, wherein in the fourth step, ultrasonic vibration is further applied to the bonding surface contact portion. 5. On the joint surface, before the fourth step of heating the contact portion, an adhesive material that evaporates or sublimes at a temperature lower than the transition point of the quartz glass material is used to surround the contact portion. 2. The method according to claim 1, wherein
5. The method for joining quartz glass according to any one of 4 to 4.