JP2002087847A - Vertical type ion exchange treating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a structure which contributes to the simplification and downsizing of the subject device and dispenses with a smaller amount of molten salt and to manufacture low-loss optical elements at a good yield. SOLUTION: The device is so constituted that the one surface of a glass substrate 20 comes into contact with the positive pole side molten salt 10 and another surface into contact with the negative pole side molten salt 14. The device includes a molten salt container 12 in which the positive pole side molten salt is put and a container-like substrate holder 16 in which the negative pole side molten salt is put. The substrate holder has an opening at its flank and this opening is made attachable and detachable so as to be liquid-tightly closed by the glass substrate 20. The substrate holder is inserted into the molten salt container, by which the glass substrate is immersed into the molten salt so as to face perpendicularly.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vertical ion exchange treatment apparatus having a structure in which one surface of a glass substrate is in contact with a molten salt on a positive electrode side and the other surface is in contact with a molten salt on a negative electrode side. The present invention relates to a vertical ion exchange processing apparatus in which a container-like substrate holding jig having an opening on a side surface and closed in a liquid-tight manner with a glass substrate is inserted into a salt container.
This vertical ion exchange processing apparatus is useful when, for example, a micro optical element such as an optical planar circuit or a flat microlens is manufactured using an electric field ion exchange method.

[0002]

2. Description of the Related Art In recent years, various methods for forming an optical waveguide or a microlens on a glass substrate by an ion exchange method have been proposed. A typical method is to form an ion permeation preventing mask having an opening of a desired waveguide pattern or lens pattern on the surface of a glass substrate, and to pass alkali ions in the glass substrate through this opening to increase the refractive index. In this case, an optical waveguide or a microlens is formed on the surface of the glass substrate by exchanging it for internal diffusion.

The ion exchange method can be roughly classified into a thermal ion exchange method in which no electric field is applied and an ion exchange method in which an electric field is applied. Among them, the electric field application ion exchange method can move ions deeper by applying an electric field during ion exchange. Therefore, for example, in forming an optical waveguide, a two-stage ion exchange method using a thermal ion exchange method in the first stage and an electric field application ion exchange method in the second stage is common.

[0004] By the way, as an ion exchange treatment apparatus,
There have been proposed a horizontal type in which a glass substrate is immersed horizontally in a molten salt and a vertical type in which a glass substrate is immersed vertically in a molten salt. In any case, the molten salt on the positive electrode side contacts one surface of the glass substrate, and the molten salt on the negative electrode side contacts the other surface. Here, the ion exchange surface of the glass substrate is on the positive electrode side. Therefore, in the case of the horizontal type, the ion exchange surface faces downward. A metal plate or the like is placed in a molten salt as an electrode. When the molten salt container is made of metal, the container itself becomes an electrode.

As an example of a conventional vertical ion exchange processing apparatus, two liquid holding members forming a container capable of injecting and holding a liquid by being in close contact with a flat plate are opposed to each other with one glass substrate interposed therebetween. (See, for example, JP-A-63-14).
No. 4147). The positive electrode is inserted into one molten salt, and the negative electrode is inserted into the other molten salt to perform electric field application ion exchange.

[0006]

The horizontal ion exchange processing apparatus has a relatively simple structure, but bubbles generated by an electrochemical reaction from the positive electrode adhere to the lower surface of the glass substrate (that is, the ion exchange surface) and remain. Sometimes. An electric field is not applied to the portion to which the bubbles are attached because the portion is not in contact with the molten salt. Further, when bubbles attached to the surface move in some way during the application of an electric field, distribution occurs in the depth direction of the waveguide formed by ion exchange. These change the embedment depth of the waveguide and result in increased losses in the resulting optical element. Further, after the electric field application ion exchange, when the glass substrate is slowly cooled, the molten salt on the negative electrode side, that is, the molten salt on the upper surface of the glass substrate may be solidified and condensed, so that the glass substrate may be damaged.

On the other hand, in the case of the vertical type, although there is an advantage that problems such as adhesion of air bubbles hardly occur, there is a problem that the apparatus is large-scale and it is difficult to mass-produce optical elements structurally.

An object of the present invention is to provide a vertical ion-exchange treatment apparatus having a structure capable of simplifying and miniaturizing the apparatus and reducing the amount of molten salt. Another object of the present invention is to provide a vertical ion-exchange processing apparatus which can manufacture low-loss optical elements with high yield and is excellent in mass productivity.

[0009]

SUMMARY OF THE INVENTION The present invention is a vertical ion-exchange treatment apparatus in which one surface of a glass substrate is in contact with a molten salt on a positive electrode side and the other surface is in contact with a molten salt on a negative electrode side. In the present invention, a molten salt container containing the molten salt on the positive electrode side and a container-shaped substrate holding jig for containing the molten salt on the negative electrode side are provided, and the substrate holding jig has an opening on a side surface and the opening. Is detachable so as to be closed in a liquid-tight manner with a glass substrate, and by inserting a substrate holding jig into the molten salt container, the glass substrate is immersed in the molten salt in a vertical direction. Is configured.

The container-shaped substrate holding jig includes a container-shaped jig body having an opening on a side surface, a heat-resistant spacer, and a glass substrate holding jig. A liquid-tight state is obtained by pressing the substrate against the jig body. The holding jig is fixed with screws.

[0011] The substrate holding jig has, for example, a flat rectangular parallelepiped shape and an opening slightly smaller than the glass substrate is formed on a wide area side surface thereof. If the openings are formed on both side surfaces facing each other and the glass substrate is detachable so as to cover each opening, two substrates can be processed simultaneously. In particular, in the case of the substrate holding jig having such a flat structure, a structure in which a portion expanded and opened above a flat rectangular parallelepiped portion is preferable. When a plurality of substrate holding jigs are juxtaposed in a molten salt container in which a molten salt on the positive electrode side is put, it is possible to simultaneously perform ion exchange processing on a large number of glass substrates. Even when a plurality of substrate holding jigs are juxtaposed, it is effective that the substrate holding jigs have a flat structure as described above.

In addition, the substrate holding jig may have a polygonal cylindrical shape, an opening formed in each side surface thereof, and a glass substrate detachable so as to cover each opening.
It may be a regular square cylinder or a regular hexagon cylinder.

The substrate holding jig is made of an electrically insulating material such as ceramics or glass. For example, Al ₂ O ₃ , Mg
O, SiO ₂ or a composite compound.

In the furnace, in addition to the molten salt container into which the substrate holding jig is inserted, another container is installed.
It is also useful that the molten salt on the negative electrode side in the substrate holding jig can be disposed in another container. In addition, a first container containing a molten salt for performing the first-stage ion exchange, a second container containing a molten salt that does not contain a valence ion and does not contribute to ion exchange, and a second stage in the furnace. A third container containing a molten salt for performing the ion exchange is installed, and the substrate holding jig on which the glass substrate is mounted is connected to the molten salt in the first container, the molten salt in the second container, The configuration in which the two-stage ion exchange can be continuously performed by sequentially immersing in the molten salt in the container No. 3 is also effective.

When the vertical ion exchange treatment apparatus as described above is used, the first-stage ion exchange is performed with the molten salt in the first container, and then immersed in the molten salt in the second container. The operation of removing the molten salt for performing the first-stage ion exchange attached to the glass substrate and subsequently performing the second-stage ion exchange with the molten salt in the third container is continuously and efficiently performed. It can be performed well, and an optical element such as an optical waveguide element or a graded index planar microlens can be manufactured. In this case, when a plurality of substrate holding jigs on which glass substrates are mounted are prepared and ion exchange is performed at the same time, ion exchange processing of a large number of glass substrates can be efficiently performed.

[0016]

FIG. 1 is a schematic diagram showing one embodiment of a vertical ion exchange apparatus according to the present invention. This apparatus is useful, for example, for manufacturing an optical waveguide device. Basically, the vertically arranged glass substrate is configured so that one surface thereof is in contact with the molten salt on the positive electrode side and the other surface is in contact with the molten salt on the negative electrode side. Since the glass substrate is arranged vertically, it is called a vertical type.

This vertical ion exchange apparatus comprises a molten salt container 12 in which the positive molten salt 10 is placed, and a container-like substrate holding jig 16 in which the negative molten salt 14 is placed.
They are housed in an electric furnace 18. Substrate holding jig 16
Has an opening on the side surface and is detachable so that the opening is closed in a liquid-tight manner with the glass substrate 20, and as shown in FIG. 16
Is inserted, the glass substrate 20 is immersed in the molten salt in the vertical direction. Electrodes 22, 24 in both molten salts
Is inserted and connected to a DC power supply 26 to apply a DC electric field to the glass substrate 20.

The substrate holding jig is desirably made of a material having a sufficiently large electric resistance to the glass substrate. Further, a material that is not ion-exchanged in order to prevent a change in components of the molten salt is preferable. Generally, a material containing an alkali ion undergoes ion exchange and has low electric resistance. The glass substrate is an optical element that forms an optical waveguide or the like therein, and is a glass containing an alkali metal. Therefore, if a material containing as little alkali metal as possible is selected as the substrate holding jig, the electric resistance is sufficiently large and ion exchange does not occur. Specifically, it is made of ceramics or glass, for example, one made of Al ₂ O ₃ , MgO, SiO ₂ or a composite compound.

FIG. 3 shows an example of the substrate holding jig. Here, the substrate holding jig main body 30 preferably has a flat rectangular parallelepiped shape, and has a structure in which an opening 32 slightly smaller than the glass substrate is formed on a wide area side surface thereof. The glass substrate 20 is closed in a liquid-tight manner with the heat-resistant spacer 34 interposed therebetween. The holding of the glass substrate 20 may be performed by any method.

FIG. 4 shows an example of the holding state of the glass substrate. The container-shaped substrate holding jig has a container-shaped jig main body 30 having an opening 32 on a side surface, a heat-resistant spacer 34, and a glass substrate holding jig 36, and the glass substrate 20 is held by the holding jig 36. A liquid-tight state is obtained by pressing the jig body 30 through the heat-resistant spacer 34. Here, the holding jig 36 has a ring shape, and the screws 38 are dispersedly arranged at a plurality of positions (here, four positions) around the ring. On the other hand,
A nut portion 40 is provided around the opening of the jig main body 30 correspondingly. By screwing each screw 38 to the nut portion 40, the glass substrate 20 is pressed by the pressing jig 36 to the jig main body 30 via the heat-resistant spacer 34 to be in a liquid-tight state. Here, irregularities may be circumferentially arranged on one or both of the periphery of the opening of the jig main body and the glass substrate facing surface of the holding jig to enhance the adhesion between the members.

FIG. 5 shows another example of the substrate holding jig. FIG.
In the example shown in FIG. 2A, a flat rectangular parallelepiped is formed, and openings 32 slightly smaller than the glass substrate are formed on both sides of the wide area so as to face each other.
Is a structure in which a glass substrate can be attached and detached so as to cover. The use of this substrate holding jig enables simultaneous processing of two glass substrates. The example shown in FIG. 5B has a structure in which a portion 42 that expands above a flat rectangular parallelepiped portion is continuous. An opening 32 slightly smaller than the glass substrate is formed on the wide area side surface, and the glass substrate is detachable so as to cover the opening 32. The openings may be formed so as to face both wide-area side surfaces. The molten salt raw material put in the substrate holding jig needs to be used in a large amount because the raw material of the molten salt decreases in volume when it is melted. For this purpose, a structure in which the upper portion is expanded is effective. When a substrate holding jig having such a structure is used, a large lump of raw material can be directly contained.

As shown in FIG. 6, a plurality (three in this case) of molten salt containers 12 containing a molten salt 10 on the positive electrode side for performing ion exchange are arranged in an electric furnace 18 in parallel. The substrate holding jig 16 on which the molten salt container 20 is mounted
2 are prepared, the molten salt 14 on the negative electrode side is put into each substrate holding jig 16, and the substrate holding jig 16 having the glass substrates 20 mounted in the molten salt 10 of each molten salt container 12 is prepared.
Respectively. Thus, a large number of glass substrates 20 can be subjected to ion exchange processing simultaneously and in parallel. For this purpose, the substrate holding jig 16 preferably has a flat structure as described above. Multiple molten salt containers 12
Can be closely arranged, and the electric furnace 18 can be downsized. In addition, in the following examples including this example, illustration of electrodes, power supplies, and the like is omitted for simplification of the drawings.

The substrate holding jig may have a polygonal cylindrical shape with openings formed on each side surface thereof, and a structure in which a glass substrate can be attached and detached so as to cover each opening. In the example shown in FIG. 7, the substrate holding jig has a regular square cylindrical shape, and has an opening 32 formed on each side surface thereof, and has a structure in which a glass substrate can be attached and detached so as to cover each opening. In the example shown in FIG. 8, the substrate holding jig has a regular hexagonal cylindrical shape, and has an opening 32 formed on each side surface thereof, and has a structure in which a glass substrate can be attached and detached so as to cover each opening. The tubular body can be held by the hanging tool 44.

As shown in FIG. 9, it is effective to provide another container 46 in the electric furnace 18 in addition to the molten salt container 12 into which the substrate holding jig 16 is inserted. The ion exchange processing operation is performed in a state as shown in FIG. Then, FIG.
As shown in B, the substrate holding jig 16 is tilted by 90 degrees or more, and the negative electrode side molten salt 14 in the substrate holding jig 16 flows out and is discarded in another container 46. By doing so, it is possible to prevent the glass substrate from being damaged when the negative electrode-side molten salt in the substrate holding jig solidifies during slow cooling.

As shown in FIG. 10, a first container 52 containing a molten salt 50 for performing the first-stage ion exchange in the electric furnace 18 does not contain monovalent ions and does not contribute to ion exchange. If the second container 56 containing the molten salt 54 and the third container 60 containing the molten salt 58 for performing the second-stage ion exchange are installed, the two-stage ion exchange process can be performed continuously. Substrate holding jig 16 with glass substrate 20 mounted
Is immersed in the molten salt 50 in the first container 52 to perform the first-stage ion exchange, and then the substrate holding jig 16 on which the glass substrate 20 is mounted is immersed in the molten salt 58 of the second container 60. To remove the molten salt for the first stage ion exchange,
Subsequently, the substrate holding jig 16 on which the glass substrate 20 is mounted
Is immersed in the molten salt 58 in the third container 60 to perform the second-stage ion exchange. In this way, it becomes possible to continuously and efficiently form the embedded optical waveguide in the glass substrate.

By using this apparatus, an alkali element in a glass substrate is ion-exchanged with a high-refractive-index ion in a molten salt, and an optical waveguide or a microlens having a high-refractive-index distribution is formed in the glass substrate. Is obtained.

[0027]

As described above, since the present invention is basically of a vertical type, it is difficult for air bubbles and impurities to adhere to a glass substrate, so that a high-quality optical element can be manufactured with a high yield.

Further, the apparatus of the present invention is suitable for miniaturization, can perform ion exchange twice in a continuous manner, or can process a large number of glass substrates simultaneously in parallel. Excellent mass productivity.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing one embodiment of a vertical ion exchange treatment apparatus according to the present invention.

FIG. 2 is an explanatory diagram at the time of setting.

FIG. 3 is an explanatory view showing an example of a substrate holding jig.

FIG. 4 is an explanatory view showing an example of the substrate holding structure.

FIG. 5 is an explanatory view showing another example of the substrate holding jig main body.

FIG. 6 is an explanatory view showing still another example of the substrate holding jig main body.

FIG. 7 is an explanatory view showing another example of the substrate holding jig main body.

FIG. 8 is an explanatory diagram showing an example of a use state of the device of the present invention.

FIG. 9 is an explanatory view showing another example of a use state of the device of the present invention.

FIG. 10 is an explanatory view showing still another example of a use state of the device of the present invention.

[Explanation of symbols]

 Reference Signs List 10 molten salt on positive electrode side 12 molten salt container 14 molten salt on negative electrode 16 substrate holding jig 18 electric furnace 20 glass substrate 22, 24 electrode 26 DC power supply

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Tomoyuki Hayashi 5-36-11 Shimbashi, Minato-ku, Tokyo Fuji Electric Chemical Co., Ltd. F-term (reference) 2H047 PA13 4G059 AA08 AC09 HB03

Claims (10)

[Claims] 1. An ion exchange treatment apparatus configured such that one surface of a glass substrate is in contact with a molten salt on a positive electrode side and the other surface is in contact with a molten salt on a negative electrode. , Comprising a container-shaped substrate holding jig into which the molten salt on the negative electrode side is to be put, the substrate holding jig has an opening on a side surface and is detachable so that the opening is liquid-tightly closed by a glass substrate. Wherein the glass substrate is vertically immersed in the molten salt by inserting a substrate holding jig into the molten salt container. 2. The vertical ion exchange apparatus according to claim 1, wherein the substrate holding jig has a flat rectangular parallelepiped shape, and an opening slightly smaller than the glass substrate is formed on a wide area side surface thereof. 3. The vertical ion exchange apparatus according to claim 2, wherein the openings are formed on both opposing side surfaces, and the glass substrate is detachable so as to cover the respective openings. 4. The vertical ion-exchange processing apparatus according to claim 2, wherein the substrate holding jig has a shape in which a portion expanded above a flat rectangular parallelepiped portion is continuous. 5. The vertical ion as claimed in claim 1, wherein a plurality of substrate holding jigs are juxtaposed in a molten salt container into which the molten salt on the positive electrode side is placed, and ion exchange treatment is enabled at the same time. Exchange processing equipment. 6. The vertical type according to claim 1, wherein the substrate holding jig has a polygonal cylindrical shape, an opening is formed on each side thereof, and a glass substrate is detachable so as to cover each opening. Ion exchange processing equipment. 7. A container-shaped substrate holding jig includes a container-shaped jig main body having an opening on a side surface, a heat-resistant spacer, and a glass substrate pressing jig. The vertical ion exchange processing apparatus according to any one of claims 1 to 6, wherein the glass substrate is held in a liquid-tight state by pressing the glass substrate against the jig body. 8. The substrate holding jig is made of Al ₂ O ₃ , MgO,
_{2. The} method according to claim 1, wherein said composition is composed of SiO ₂ or a composite compound.
The vertical ion exchange treatment apparatus according to any one of claims 1 to 7. 9. A separate container is installed in the furnace in addition to the molten salt container into which the substrate holding jig is inserted, and after the ion exchange treatment operation, the negative electrode side molten salt in the substrate holding jig is transferred to another container. 9. The vertical ion exchange treatment device according to claim 1, wherein the ion exchange treatment device can be disposed of. 10. A first container containing a molten salt for performing the first-stage ion exchange in an electric furnace, and a second container containing a molten salt containing no monovalent ions and not contributing to ion exchange. A third container containing a molten salt for performing the second-stage ion exchange is installed, and the substrate holding jig on which the glass substrate is mounted is moved to the molten salt in the first container and the molten salt in the second container. Molten salt,
The vertical ion-exchange treatment apparatus according to any one of claims 1 to 8, wherein the two-stage ion exchange can be continuously performed by being sequentially immersed in the molten salt in the third container.