JPS59804B2 - Manufacturing method of optical fiber connection board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing an optical fiber connecting board used for connecting optical fibers together.

This type of optical fiber connection board requires highly precisely formed grooves for arranging the optical fibers, since the fibers must be aligned with each other with high precision. For this reason, conventionally, on the main surface of a silicon single crystal substrate with an alignment flat (orientation flat) formed on the side surface prepared in advance,
An etching protection film made of an oxide film is formed, and then an optical fiber installation groove is formed on the oxide film, which includes an alignment strip pattern and a first optical fiber installation groove formation pattern. A photomask is used to align the alignment strip pattern with the alignment plane of the silicon single crystal substrate to form a second optical fiber placement pattern corresponding to the optical fiber placement groove formation pattern. Forming an etching mask for forming grooves for arranging optical fibers having a pattern for forming grooves, and then etching the etching protection film using this etching mask for forming grooves for arranging optical fibers as a mask. A third layer corresponding to the pattern for forming the second optical fiber groove is formed on the etching protection film.
A pattern for forming a groove for installing an optical fiber is formed, and then,
By performing orientation selective etching on the silicon single crystal substrate using the etching protection film formed with the third optical fiber groove forming pattern as a mask,
A manufacturing method is provided in which a desired optical fiber connection substrate is obtained by forming an optical fiber placement groove corresponding to the third optical fiber placement groove formation pattern on the main surface side of a silicon single crystal substrate. Proposed. However, in this manufacturing method, a silicon single crystal substrate is used, and a groove for arranging an optical fiber is formed in the silicon single crystal substrate by selectively etching the surface orientation. The purpose is to obtain a substrate for fiber connection.

Therefore, the above-described manufacturing method can, in principle, make it possible to obtain grooves for arranging optical fibers with high precision. However, in the case of the above-mentioned manufacturing method, the silicon single crystal substrate is etched by selectively etching the silicon single crystal substrate using the etching protection film formed with the third optical fiber groove formation pattern as a mask. On the main surface side of
In the process of forming the groove for arranging the optical fiber, the etching protection film is an oxide film, so the etching protection film is removed by an etchant such as a KOH solution used in the orientation selective etching process for a silicon single crystal substrate. Therefore, a non-negligible amount is eluted.

Therefore, during orientation selective etching on a silicon single crystal substrate, the width of the third optical fiber groove formation pattern formed in the etching protection film becomes wider over time. Therefore, in the above-mentioned manufacturing method, from the step of forming an etching protection film on the silicon single-crystal substrate to the above-mentioned surface orientation selective etching process on the silicon single-crystal substrate, optical fiber installation grooves are formed in the silicon single-crystal substrate. By performing the steps up to the step of forming the silicon single crystal substrate only once, the required depth (50
500 μm), the third optical fiber groove formed in the etching protection film has an unacceptably large width corresponding to its depth. The width of the forming pattern becomes wider.

Therefore, the width of the optical fiber groove that is finally formed in the silicon single crystal substrate is wider than the initial width of the third optical fiber groove formation pattern that is formed in the etching protection film. It is formed to have an unacceptably large width, and an unacceptably large depth, which is greater than the intended depth.
However, in the above-mentioned manufacturing method, from the step of forming an etching protection film on the silicon single-crystal substrate to the above-mentioned surface orientation selective etching process on the silicon single-crystal substrate, a groove for arranging the optical fiber is formed in the silicon single-crystal substrate. If the steps up to the forming step are repeated several times to form a groove for arranging an optical fiber with a required depth in a silicon single crystal substrate, each time the silicon single crystal substrate is subjected to surface orientation etching. Even if the width of the third optical fiber groove formation pattern formed in the etching protection film becomes wider over time, the increased width will depend on the plane orientation relative to the silicon single crystal substrate each time. The selective etching process time ranges from the step of forming the etching protection film on the silicon single crystal substrate mentioned above to the formation of the groove for arranging the optical fiber in the silicon single crystal substrate by the plane direction selective etching process of the silicon single crystal substrate mentioned above. The process up to the process of forming the optical fiber is completed just once, which is shorter than when forming a groove for installing an optical fiber with the required depth in a silicon single crystal substrate. It is something that cannot happen.

For this reason, the optical fiber groove that is finally formed in the silicon single crystal substrate is equal to the initial width of the third optical fiber groove forming pattern formed in the etching protection film in each etching process. It is formed by having a width that is increased by an allowable width from the original depth, and a depth that is increased by an allowable depth from the intended depth. Therefore, when obtaining an optical fiber connection substrate in which a groove for installing an optical fiber of a required depth is formed in a silicon single crystal substrate by the above-mentioned manufacturing method, it is necessary to form an etching protection layer on the silicon single crystal substrate as described above. The process from forming a film to forming a groove for arranging an optical fiber in a silicon single crystal substrate by the above-mentioned surface orientation selective etching process on the silicon single crystal substrate must be repeated several times.

Therefore, when obtaining the desired optical fiber connection substrate by the above-mentioned manufacturing method, it takes a lot of time and
Each time, it is necessary to align the alignment strip pattern of the photomask for forming grooves for optical fiber placement with the alignment plane of the silicon single crystal substrate, and since this involves an error, the final This method has a disadvantage in that the precision of the optical fiber groove formed in the silicon single crystal substrate is reduced.

Furthermore, in the case of the above-mentioned manufacturing method, the second optical fiber is arranged using a photomask for positioning the optical fiber, which is aligned with the band pattern for positioning and the plane for positioning of the silicon single crystal substrate. An etching mask for forming an optical fiber groove is obtained, and based on this, a third pattern for forming an optical fiber groove is formed on the etching protection film, and The etching protection film having the third optical fiber groove formation pattern is used to form an optical fiber groove in the silicon single crystal substrate.

By the way, it is undeniable that the alignment plane of the silicon single crystal substrate is accompanied by an angular error with respect to the plane orientation of the silicon single crystal substrate. For this reason, even if the alignment strip pattern of the optical fiber placement photomask and the alignment plane of the silicon single crystal substrate are accurately aligned, the third optical fiber formed on the etching protection film is The groove forming pattern for arrangement is formed with an angular error with respect to the plane orientation of the silicon single crystal substrate. Therefore, in the case of the above-mentioned manufacturing method, even if the alignment strip pattern of the optical fiber placement photomask and the alignment plane of the silicon single crystal substrate are accurately aligned, the optical fiber is formed on the silicon single crystal substrate. Although the optical fiber groove should be formed uniformly in each part with the width of the third optical fiber groove forming pattern formed in the etching protection film, It is formed to have a width that repeatedly changes.

Therefore, the above-described manufacturing method has drawbacks such as the fact that it is extremely difficult to form the optical fiber groove with high precision and without errors.

Therefore, the present invention uses a silicon single-crystal substrate and performs surface orientation selective etching on the silicon single-crystal substrate to form a groove for arranging an optical fiber in the silicon single-crystal substrate. A new substrate for connecting optical fibers can be obtained without the above-mentioned drawbacks by forming grooves for installing optical fibers having the desired depth. This will become clear from the detailed description below. FIGS. 1 to 14 show an example of a method for manufacturing an optical fiber connection substrate according to the present invention. As shown in FIG. A silicon single crystal substrate 3 is prepared in advance, and an etching protection film 4 made of a nitride film is formed on the main surface 2 of the silicon single crystal substrate 3, as shown in FIG.

Next, on this etching protection film 4, as shown in FIG.
Next, as shown in FIG. 4, an alignment strip pattern 7 is formed on the photoresist film 5 at a lower position on a transparent substrate 6 made of glass, for example. A photomask 9 for forming a surface orientation mark, in which a circular pattern 8 for forming a surface orientation mark is formed at the four corners of a transparent substrate 6, is attached to a band pattern 7 for alignment thereof, and a silicon single crystal substrate. 3, and arranged in close contact with the alignment plane 1.

In this case, as will become clear from what will be described later, it should be noted that the circular pattern 8 for forming a surface orientation mark of the photomask 9 for forming a surface orientation mark is literally a circular pattern. Next, using this photomask 9 as a mask, the photoresist film 5 is exposed to ultraviolet rays, followed by a development process, and as shown in FIG. An etching mask 11 for forming a surface orientation mark is formed having a circular pattern 10 for forming a surface orientation mark formed of holes corresponding to the circular pattern 8 for forming a mark.

Next, the etching mask 11 for forming the plane orientation mark is
As shown in FIG. 6, etching is performed on the etching protection film 4 using the etching mask as a mask, and then the etching mask 11 for forming surface orientation marks is removed from above the etching protection film 4. A circular pattern 12 for forming a surface orientation mark, which includes holes corresponding to the circular pattern 10 for forming a surface orientation mark, is formed in the etching protection film 4 .

Next, using the etching protection film 4 formed with the circular pattern 12 for forming a surface orientation mark as a mask, the silicon single crystal substrate 3 is subjected to a surface orientation selective etching process using an etchant such as a KOH solution. As shown in FIG. 7, grooves having square patterns corresponding to the circular patterns 12 for forming surface orientation marks and circumscribing the circular patterns 12 for forming surface orientation marks are formed on the main surface 2 side of the silicon single crystal substrate 3. Surface orientation mark 1
form 3.

In this case, since the circular pattern 12 for forming surface orientation marks formed on the etching protection film 4 is a circular pattern,
It should be noted that the surface orientation mark 13 is formed to have a square pattern, and each side of the square pattern matches the surface orientation of the silicon single crystal substrate 3.

Note that the aspect in which each side of the square pattern of the surface orientation mark 13 matches the surface orientation of the silicon single crystal substrate 3 means that the main surface of the silicon single crystal substrate 3 is the (100) plane, and the surface orientation mark When using an etchant using a KOH solution in the surface orientation selective etching process when forming 13,
Since the groove constituting the surface orientation mark 13 is formed to have an inner surface formed by the (111) plane, each side of the square pattern of the surface orientation mark 13 is formed on the silicon single crystal substrate 3.
It has an aspect in which it extends on a straight line parallel to the intersection line between the (100) plane and the (111) plane. Incidentally, the circular pattern 1 for forming surface orientation marks formed on the etching protection film 4
2 is a square pattern rather than a circular pattern, unless each side of the square pattern matches the plane orientation of the silicon single crystal substrate 3, the plane orientation mark 13 will have each side aligned with the silicon single crystal substrate 3. It is not formed as having a square pattern that matches the plane orientation of the substrate 3. Next, as shown in FIG. 8, a photoresist film 15 similar to the photoresist film 5 described above is applied and disposed on the etching protection film 4, and then, on this photoresist film 15, As shown in FIG. 9, alignment strip patterns 17 are formed at lower positions on a transparent substrate 16 made of glass, for example, and square alignment alignment patterns are formed at four corners of the transparent substrate 16. A photomask 20 for forming grooves for optical fiber placement, in which a grating pattern 18 is formed and a groove formation pattern 19 for optical fiber placement is further formed at the center position on the translucent substrate 16, is formed by forming the strip pattern 17. and the alignment plane 1 of the silicon single-crystal substrate 3, the square lattice pattern 18 for plane orientation alignment, and the plane orientation mark 13 formed on the main surface 2 side of the silicon single-crystal substrate 3. After aligning the surface orientation,
Place them close together.

In this case, a photomask 20 for forming grooves for arranging optical fibers is used.
The surface orientation alignment between the square lattice pattern 18 for surface orientation alignment of the silicon single crystal substrate 3 and the surface orientation mark 13 of the silicon single crystal substrate 3 is performed when the optical fiber placement groove forming pattern 18 is a square lattice pattern (not just a square pattern). It should be noted that with high precision, it can be easily done.

Next, using the photomask 20 as a mask, the photoresistor film 15 is exposed to ultraviolet rays, followed by a development process, and as shown in FIG. Etching mask 2 for forming optical fiber grooves 2 having a pattern 21 for forming optical fiber grooves formed of holes corresponding to the forming patterns 19
form 2.

In this case, a pattern 23 corresponding to the square grid pattern 18 for surface orientation alignment of the photomask 20 is formed on the mask 22. Next, the etching protection film 4 is etched using the etching mask 22 for forming grooves for optical fiber placement as a mask, and then the etching mask 22 for forming grooves for optical fiber placement is used as a mask. By dissolving from above the etching protection film 4, the etching protection film 4 is removed as shown in FIG.
Then, an optical fiber arrangement groove forming pattern 24 consisting of holes corresponding to the optical fiber arrangement groove forming pattern 21 is formed.

Next, the silicon single crystal substrate 3 is subjected to a surface orientation selective etching process using an etchant such as a KOH solution, using the etching protection film 4 formed with the optical fiber groove forming pattern 24 as a mask. By doing this, as shown in FIG.
A pattern 24 for forming grooves for arranging optical fibers is formed on the main surface 2 side of the
An optical fiber installation groove 25 having a pattern corresponding to the pattern is formed.

In this case, on the main surface 2 side of the silicon single crystal substrate 3,
A pattern 26 corresponding to the pattern 24 for forming an optical fiber groove is formed. Next, a silicon single crystal substrate 3 having the optical fiber groove 25 formed therein is prepared.
was then cut along the cutting line 27 shown by the chain line in FIG. 13 in order to cut out the area where the optical fiber groove 25 is formed, and thus, as shown in FIG. 14, The desired optical fiber connection substrate is obtained, in which an optical fiber installation groove 25 is formed on the main surface 2 side of a silicon single crystal substrate 3.

The above is an example of the manufacturing method of the optical fiber connection substrate according to the present invention. According to this manufacturing method, the etching protection film 4 on which the optical fiber arrangement groove forming pattern 24 is formed is used as a mask. , silicon single crystal substrate 3 is formed by surface orientation selective etching treatment on silicon single crystal substrate 3.
In the step of forming the optical fiber groove 25 on the main surface 2 side of the etching, since the etching protection film 4 is a nitride film, the surface orientation of the etching protection film 4 with respect to the silicon single crystal substrate 3 is KO used during selective etching process
It is not substantially eluted by etchants such as H solution.

For this reason, during the surface orientation selective etching process on the silicon single crystal substrate 3, the width of the optical fiber groove forming pattern 24 formed in the etching protection film 4 is different from that in the conventional manufacturing method described at the beginning. As such, there is virtually no tendency for the width to widen over time. Therefore, according to the manufacturing method of the present invention, the required depth (50 mm 500 μm), the width of the optical fiber groove is substantially equal to the width of the optical fiber groove forming pattern 24 formed on the etching protection film 4. It is formed to have a width equal to , and a desired depth.

Therefore, according to the manufacturing method of the present invention, in order to obtain the optical fiber groove 25 of the required depth (50 to 500 μm) in the silicon single crystal substrate 3, the steps from the steps described above in FIG. Only one step is required up to the step shown in FIG.
A groove for arranging an optical fiber can be obtained with high precision.

Further, according to the manufacturing method of the present invention, the photomask 20 for forming grooves for arranging optical fibers is formed by forming the strip pattern 17 for alignment.
and the alignment plane 1 of the silicon single crystal substrate 3, and the square lattice pattern for surface orientation alignment, and the groove having a square pattern formed in advance on the main surface 2 side of the silicon single crystal substrate 3. By aligning the surface orientation with the surface orientation mark 13, an etching mask 22 for forming optical fiber grooves having a pattern 19 for forming optical fiber grooves is obtained, and based on this, etching is performed. A groove forming pattern 2 for optical fiber placement is formed on the protective film 4.
4, and using the etching protection film 4 having the optical fiber groove forming pattern 24, an optical fiber groove 25 is formed in the silicon single crystal substrate 3. There is.

By the way, the surface orientation mark 13 previously formed on the silicon single crystal substrate has a square pattern, and each side of the square pattern matches the surface orientation of the silicon single crystal substrate 3.

For example, if the main surface of the silicon single crystal substrate 3 is the (100) plane and an etchant using a KOH solution is used for the surface orientation selective etching process when forming the surface orientation mark 13, the silicon single crystal substrate 3 is Since the groove constituting the surface orientation mark 13 is formed to have an inner surface made of a (111) plane, the surface orientation mark 13
Each side of the square pattern of (
It extends on a straight line parallel to the intersection line of the (100) plane and the (111) plane, which corresponds to the plane orientation of the silicon single crystal substrate 3. For this reason, the photomask 20 for forming grooves for arranging optical fibers is connected to the alignment strip pattern 17 and the alignment plane 1 of the silicon single crystal substrate 3.
A square grating pattern for positioning and surface orientation alignment, and a surface orientation mark 1 formed by a groove having a square pattern previously formed on the main surface 2 side of the silicon single crystal substrate 3.
3, the straight lines extending in the horizontal (or vertical) direction of the square lattice pattern for surface orientation alignment of the optical fiber groove forming photomask 20 and the silicon single crystal Horizontal (or vertical) of the square pattern of the plane orientation mark 13 formed on the substrate 3
The alignment strip pattern 17 of the optical fiber groove forming photomask 20 and the alignment plane 1 of the silicon single crystal substrate 3 are aligned so that the sides extending in the direction are parallel to each other. When alignment is performed, the alignment plane 1 of the silicon single-crystal substrate 3 is accompanied by an angular error with respect to the plane orientation of the silicon single-crystal substrate 1. Band-shaped pattern 17 for alignment of a photomask for formation and silicon single crystal substrate 3
Even if an angular error remains between the etching film and the alignment plane 1, the optical fiber groove forming pattern 24 formed in the etching film will be at an angle with respect to the plane orientation of the silicon single crystal substrate 3. It is formed so that the surface orientation coincides with that of the silicon single crystal substrate 3 without any error.

Therefore, according to the manufacturing method of the present invention, even if the alignment plane 1 of the silicon single crystal substrate 3 is
This method has great features such as being able to easily form a groove for arranging an optical fiber with high precision and without error even if there is an angular error with respect to the surface orientation of the optical fiber. In the above description, the groove 25 for arranging the optical fiber is formed in the silicon single crystal substrate 3 as shown in FIG.
Part 3 for arranging the wire diameter (for example, about 100 ttm)
1 and a part 32 for arranging an optical fiber core part (the diameter of which is, for example, about 700 μm), and the optical fiber arranging groove 2 of the optical fiber arranging groove 25.
At the same time as the guide rod (rod diameter: 10001 mm)
Although the detailed explanation is omitted, the guide rod wiring groove 25' for wiring the optical fiber is formed as shown in FIG. 15. Also when it is made to be obtained on the silicon single crystal substrate 3 as a part consisting of a part 31 for arranging the strand part and a pair of parts 32 and 327 for arranging the optical fiber core part, The present invention can be applied thereto.

Furthermore, although the above description deals with the case where one optical fiber connection substrate is obtained from the silicon single crystal substrate 3, it is also possible to simultaneously obtain a plurality of optical fiber connection substrates. Without departing from the spirit of the invention,
Various modifications and changes may be made.

[Brief explanation of drawings]

1A and 13A to 13A and 13A and 13B are line plan views and cross-sectional views taken along the line B--B of successive steps showing an example of the manufacturing method of an optical fiber connection substrate according to the present invention. FIG. 14 is a schematic perspective view showing an example of an optical fiber connection substrate obtained through the sequential steps shown in FIGS. 1A and B to FIGS. 13A and B. Figure 15 is Figure 1 A and B
- FIG. 13 is a schematic perspective view showing another example of an optical fiber connection substrate obtained through steps similar to the sequential steps shown in FIGS. 13A and 13B. 1... Alignment plane, 2...
...Main surface, 3...Silicon single crystal substrate, 4
...Etching protective film, 5...15...
... Photoresist film, 6, 16 ... Transparent substrate, 7, 17 ... Band pattern for positioning,
8, 10, 12...Circular pattern for forming plane orientation marks, 9...Photomask for forming plane orientation marks, 11...Etching mask for forming plane orientation marks, 13 ...plane orientation mark, 18...
...Square grid pattern for surface orientation alignment, 19, 21
, 24...Pattern for forming grooves for arranging optical fibers, 20...Photomask for forming grooves for arranging optical fibers, 22...For forming grooves for arranging optical fibers. Etching mask, 25...Groove for installing optical fiber.

Claims (1)

[Claims] 1. A step of forming an etching protection film made of a nitride film on the main surface of a silicon single crystal substrate prepared in advance and having an alignment plane formed on the side surface, and a step of forming a second etching protection film on the etching protection film. A photomask for surface orientation mark formation having a first alignment strip pattern and a first surface orientation mark formation circular pattern is aligned with the first alignment strip pattern and the silicon single crystal substrate. forming an etching mask for forming a surface orientation mark, which has a second circular pattern for forming a surface orientation mark corresponding to the first circular pattern for forming a surface orientation mark; and an etching process for the etching protection film using the etching mask for forming a surface orientation mark as a mask, so that a third circular pattern corresponding to the second circular pattern for forming a surface orientation mark is formed on the etching protection film. a step of forming a circular pattern for forming a surface orientation mark; and a surface orientation selective etching process for the silicon single crystal substrate using the etching protection film formed with the third circular pattern for forming a surface orientation mark as a mask. A step of forming a plane orientation mark by a groove having a square pattern corresponding to the third circular pattern for forming a plane orientation mark on the main surface side of the silicon single crystal substrate, and on the etching protection film, A photomask for forming grooves for optical fiber arrangement, which has a second strip pattern for alignment, a square lattice pattern for surface orientation alignment, and a first groove formation pattern for optical fiber arrangement, Alignment by the alignment strip pattern and the alignment plane of the silicon single crystal substrate, and the square lattice pattern for surface orientation alignment and a surface orientation mark formed on the main surface side of the silicon single crystal substrate. an etching for forming an optical fiber disposing groove, the etching having a second optical fiber disposing groove forming pattern corresponding to the first optical fiber disposing groove forming pattern; The second optical fiber is disposed on the etching protective film by forming a mask for forming a groove for arranging the optical fiber, and etching the etching protective film using the etching mask for forming the optical fiber disposing groove as a mask. a step of forming a third optical fiber arrangement groove forming pattern corresponding to the optical fiber arrangement groove forming pattern; and masking the etching protection film formed by the third optical fiber arrangement groove forming pattern. arranging an optical fiber having a pattern corresponding to the third optical fiber arrangement groove forming pattern on the main surface side of the silicon single crystal substrate by performing a surface orientation selective etching process on the silicon single crystal substrate; 1. A method for manufacturing an optical fiber connection substrate, the method comprising the step of forming a groove.