JPH09328325A - Quartz substrate and production of quartz-based glass waveguide type optical part using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a quartz substrate capable of accurately aligning a waveguide type optical part with many optical fibers when simultaneously carrying out the connection thereof without causing misdetection or lacerated wounds in hands or fingers when measuring a waveguide core under a laser microscope and to provide a method for producing the quartz-based waveguide type optical part using the quartz substrate. SOLUTION: The method for producing a quartz-based glass waveguide type optical part comprises a stage for forming a core glass film on a quartz substrate 21 having 1mm thickness and a stepped part 22 having 500μm depth over a region in a width of 5mm from the outer periphery thereof at right angles of the surface with the lateral face of the quartz substrate 21 and respective rounded areas from each intersecting line of the surface and the lateral face of the quartz substrate 21 to the substrate surface and a point separated from the substrate surface by 10μm and a stage for forming an optical circuit pattern.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a quartz substrate, in particular, a circular quartz substrate used for manufacturing a silica-based glass waveguide type optical component, and a method for manufacturing a silica-based glass waveguide type optical component using the same. Is.

[0002]

2. Description of the Related Art In the fields of communication, measurement, information processing, etc., optical integrated circuits having various functions such as light combining and branching have been studied in order to utilize light at higher levels. A silica-based glass waveguide type optical component is used as an element constituting an optical integrated circuit.

FIG. 4 shows a manufacturing process of a silica glass waveguide type optical component using a quartz substrate according to the prior art. This manufacturing process is similar to the LSI manufacturing process.

First, a core glass film 12 is formed on a quartz substrate 11.
To form The core glass film 12 is made of SiO ₂ and GeO.
Made of _two . The core film can be formed by appropriately using a flame deposition method, an electron beam evaporation method, or the like, and then heating it at a high temperature in an electric furnace or a sintering furnace.

Next, a metal film 14 such as tungsten seaside is deposited on the core glass film 12. Then, a photoresist is applied on the metal film 14, and the optical circuit pattern 13 is formed by the photolithography technique.
The metal film 14 is etched by using the optical circuit pattern 13 made of this photoresist as a mask material. After that, the core glass film 12 is etched using the metal film pattern as a mask.

Finally, the waveguide core 15 formed by etching is surrounded by a porous glass layer 16, and the porous glass layer 16 is heated in an electric furnace to be transparent vitrified to form a clad 17.

If the core glass film 12 is etched only with the optical circuit pattern 13 made of photoresist, the optical circuit pattern 13 made of photoresist is etched and disappears before the glass etching to a desired depth is completed. The optical circuit cannot be manufactured correctly. Therefore, the metal film 14 is provided.

[0008]

When the porous glass layer 16 is heated to be a transparent glass, the porous glass attached to the side surface of the quartz substrate 11 is heated at a high temperature and contracts. Apply stress. This stress acts to warp the quartz substrate 11, and if the substrate warps, there is a problem that the alignment accuracy is lowered when the waveguide type optical component and a large number of optical fibers are simultaneously connected.

In order to prevent the porous glass from adhering to the side surface of the substrate, the substrate is surrounded by a ring having the same material as the quartz substrate 11 and the same thickness of 1 mm. The ring is removed after the porous glass is deposited. It was found that there is a problem that it takes time and that part of the porous glass deposited on the substrate surface is peeled off.

Further, when a portion having no porous glass is formed on the surface of the substrate, when the porous glass is heated to form transparent glass, the stress applied to the substrate becomes non-uniform and the substrate waviness occurs. This undulation also causes a decrease in alignment accuracy when a waveguide type optical component and a large number of optical fibers are simultaneously connected.

FIG. 5 is a sectional view taken along the line AA 'of the quartz substrate 1 used in the conventional manufacturing method. The vicinity of the intersection line between the surface and the side surface of the quartz substrate 1 is obliquely processed from the intersection line to the points separated by about 10 μm on the substrate surface and the side surface, respectively. This is to prevent laceration of fingers. However, the obliquely processed side surface 2 is not preferable for resist coating in the photolithography technique. That is, the excess resist at the time of application flows from the substrate surface to the side surface, and the side surface 2 is processed obliquely.
Adheres to The adhered resist is carbonized by the reactive ion etching and becomes difficult to peel off. This carbonized resist causes erroneous detection in automatic position detection when measuring the dimensions of the waveguide core with a laser microscope.

Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art, and to provide a quartz substrate and a method of manufacturing a silica glass waveguide type optical component using the quartz substrate, which is free from warpage and undulation. is there. Further, the object of the present invention is to eliminate false detection when measuring a waveguide core with a laser microscope,
It is another object of the present invention to provide a quartz substrate and a method of manufacturing a silica-based glass waveguide type optical component using the quartz substrate, which can prevent tearing of fingers.

[0013]

In order to achieve the above object, the present invention is to provide a step on the outer circumference of the quartz substrate. Further, the angle formed by the surface and the side surface of the quartz substrate was set to a right angle, and the corners near the intersection line between the surface and the side surface of the quartz substrate were slightly rounded.

[0014]

FIG. 1 is a sectional view showing a first embodiment of a quartz substrate of the present invention, in which a step 22 is formed to a thickness 1
A quartz substrate 21 of mm is shown. The step 22 can be formed by polishing. For example, the quartz substrate can be fixed to a polishing jig and rotated, and polishing can be performed with a polishing plate having a polishing cloth attached to a region where a step is provided. Alternatively, it can be chemically etched. The step has a depth of 500 μm over a region of 5 mm from the outer circumference of the quartz substrate 21.

FIG. 2 is an explanatory view showing a second embodiment of the quartz substrate of the present invention, in which the angle between the surface and the side surface of the quartz substrate 1 is set to a right angle, and the line of intersection between the surface and the side surface of the quartz substrate 1 is used. A quartz substrate 1 having roundnesses 3 on the substrate surface and the substrate side surface up to points 10 μm apart is shown. The corner roundness 3 is formed by first processing the side surface of the substrate by polishing so that the angle formed by the surface and the surface becomes a right angle, and then, by using a burner, the corner near the line of intersection between the surface and the side surface of the substrate. 10 μm from the line of intersection between the surface and the side of the substrate to the surface and the side of the substrate
The formation of roundness up to a distant point is confirmed by observation with an optical microscope. The radius of curvature of the roundness 3 is estimated to be about 6 μm.

As described above, by making the angle between the surface and the side surface of the circular quartz substrate to be a right angle and slightly rounding the corner near the intersection line, the intersection line between the surface and the side surface of the substrate at the time of resist coating is formed. Prevents excess resist from adhering to the vicinity,
Moreover, laceration of fingers can be prevented.

FIG. 3 is an explanatory view showing a manufacturing method of the present invention, in which a step 30 is provided on a quartz substrate, an angle formed by the surface and the side surface of the quartz substrate is made a right angle, and an intersection line between the surface and the side surface of the quartz substrate. A method of manufacturing a silica-based glass waveguide type optical component will be described by using the quartz substrate 31 having roundnesses 36 from the substrate surface and the substrate side surface to points 10 μm apart.

A glass film having a refractive index slightly higher than that of the substrate is formed on the quartz substrate 31 to form a core glass film. The core glass film is formed by an electron beam evaporation method or a flame deposition method. The core glass component is SiO
₂ and GeO ₂ . TiO ₂ may be used instead of GeO ₂ .

A metal film is sputtered on the surface of the core glass film to serve as a mask material for etching the core glass film. The resist is applied onto the metal film while rotating the substrate at a high speed with a spin coater. At this time, since the corners of the substrate are rounded, excess resist does not adhere. And
The resist is exposed and developed to form an optical circuit pattern.

Next, the metal film is etched using the resist as a mask material and the core glass film is etched using the metal film as a mask material by reactive ion etching. After removing the mask material, the dimensions of the waveguide core 32 produced by etching the core glass film are measured with a laser microscope.
The measurement is performed by automatically detecting the position. As described above, since the excess resist does not adhere to the vicinity of the intersection line between the substrate surface and the side surface, it is possible to eliminate erroneous recognition in the automatic detection.

Next, porous glass 33 is deposited on the quartz substrate 31 on which the waveguide core 32 is formed. At this time, the ring-shaped quartz 34 is inserted into the step 30 of the substrate. The outer diameter of the ring-shaped quartz 34 is the same as the outer diameter of the substrate, the inner diameter is 10 mm shorter than the outer diameter of the substrate, and the thickness is 500 μm. After depositing the porous glass 33, the ring-shaped quartz 34 is removed, and the substrate 31 on which the porous glass 33 is deposited is heated in an electric furnace,
A transparent glass film 35 to be a clad is obtained.

Since the step 30 is completely covered by the ring-shaped quartz 34, the porous glass does not adhere to the side surface of the substrate, which causes stress from the side surface of the substrate when the porous glass is heated to be transparent. The warp of the substrate is eliminated. Further, after depositing the porous glass, the ring-shaped quartz 34 is stepped 3
The time taken to remove from 0 is half the time required to fill the entire outer circumference of the conventional substrate having no step, so that the porous glass deposited on the surface of the substrate is not peeled off. Therefore,
Porous glass can be uniformly deposited on the substrate surface,
As a result, a waviness-free substrate is realized.

The material for the ring for filling the step may be other than quartz as long as it has the same coefficient of thermal expansion as quartz. Further, although the effect has been described by assuming that the angle formed by the surface and the side surface of the substrate is a right angle, the same effect can be obtained by forming an acute angle, that is, an inverse taper shape. The inverse tapered shape can be obtained by polishing the side surface of the substrate by setting a desired angle between the polishing jig for fixing the substrate and the polishing plate in the polishing apparatus.

[0024]

According to the present invention, warpage due to stress on the side surface of the substrate can be suppressed. As a result, when the waveguide type optical component and a large number of optical fibers are connected at the same time, the alignment can be performed with high accuracy.

Further, since the porous glass can be uniformly deposited on the surface of the substrate, the substrate does not undulate when the porous glass layer is heated to become transparent glass. Therefore, the waveguide type optical component and a large number of optical fibers can be accurately aligned at the same time. Furthermore, since no extra resist is attached near the corners of the substrate, it is possible to avoid erroneous recognition due to carbonized resist in automatic measurement of the waveguide core. Safety is maintained because measures are taken to prevent laceration of the fingers.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a quartz substrate related to a quartz substrate of a first embodiment of the present invention and provided with a step.

FIG. 2 is a sectional view of a quartz substrate having a roundness according to a second embodiment of the present invention.

FIG. 3 is an explanatory view showing a manufacturing process of a silica-based glass waveguide optical component according to the manufacturing method of the present invention.

FIG. 4 is an explanatory view showing a manufacturing process of a silica-based glass waveguide optical component according to a conventional technique.

FIG. 5 is a cross-sectional view of a quartz substrate according to a conventional technique.

[Explanation of symbols]

 1 Quartz Substrate 2 Diagonally Processed Side Surface 3 Roundness 11 Quartz Substrate 12 Core Glass Film 13 Optical Circuit Pattern 14 Metal Film 15 Waveguide Core 16 Porous Glass Layer 17 Clad 21 Quartz Substrate 22 Step 30 Steps 31 Quartz Substrate 32 Waveguide Core 33 Porous glass 34 Ring-shaped quartz 35 Clad 36 Roundness

Claims (8)

[Claims] 1. A quartz substrate having a circular shape, wherein a step is provided on the outer circumference of the quartz substrate. 2. The quartz substrate according to claim 1, wherein the region where the step is provided is 5 mm from the outer circumference of the quartz substrate. 3. The quartz substrate according to claim 2, wherein the thickness of the substrate is 1 mm. 4. The quartz substrate according to claim 3, wherein the step has a depth of 500 μm. 5. A quartz substrate characterized by slightly rounding the corners near the intersection of the surface and the side surface of the quartz substrate. 6. The quartz substrate according to claim 5, wherein the quartz substrate is rounded from a line of intersection of the surface and the side surface of the quartz substrate to a point separated by 10 μm on the substrate front surface side and the substrate side surface side, respectively. 7. A step of forming a step on the outer periphery of a quartz substrate,
A method of manufacturing a silica-based glass waveguide type optical component, comprising: a step of forming a core glass film on the quartz substrate; and a step of forming an optical circuit pattern on the core glass film. 8. A quartz system comprising: a step of forming roundness on a corner of a surface and a side surface of a quartz substrate; a step of forming a core glass film on the quartz substrate; and a step of forming an optical circuit pattern on the core glass film. Manufacturing method of glass waveguide type optical component.