JPH05288947A - Method for generating reference line for cutting of optical waveguide chip - Google Patents

Abstract

PURPOSE:To provide clear vision and enable highly precise setting by leaving a mask by covering the cutting reference line and depositing an overclad as it is when a mask where a core is formed by patterning is removed. CONSTITUTION:The overclad 6 is deposited on the top surface of the core 2 of the optical waveguide chip 1 without fail, but the cutting reference line 4 is illegible in this state and the reflection factor is made larger to enable the cutting reference line to be seen clearly. For the purpose, the reflection factor can be increased by making the depositing process on the top surface of the core 2 for the cutting reference line different, for example, by providing a reflecting layer (1) or not by depositing the overclad 6 (b), etc. Those processes are performed not by processing the part of the cutting reference line 4 in a series of processes of the manufacture of the optical waveguide chip 1. This cutting reference line 4 is provided outside the area of the optical waveguide chip 1 at a distance, a wafer 3 can be positioned with high precision, and only initial setting is required.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a cutting reference line for a ridge type optical waveguide chip. A large number of chips are integrally formed on one wafer through various processing steps, and finally the wafer is cut into individual chips to obtain one chip.

A ridge type optical waveguide chip is also surrounded by SiO ₂ having a low core refractive index on a silicon wafer, and a large number of chips are formed by pattern forming an optical waveguide with a core material having a high refractive index.

The cutting of the optical waveguide chip from the wafer requires higher dimensional accuracy as the chip becomes smaller. Since the wafer is not provided with a guide mechanism for dimensional accuracy,

[0004]

2. Description of the Related Art FIG. 6 shows a manufacturing flow of a conventional optical waveguide, FIG. 7 shows a conventional core manufacturing flow, and FIG. 8 shows a conventional wafer.

As a conventional example, the manufacture of a ridge type silica optical waveguide will be described with reference to a flow chart. As shown in FIGS. 6A to 6E, the low refractive index [SiO 2] is formed on the Si substrate 91 at (A).
₂ ] 92, and a high-refractive-index [SiO ₂ + Ge] 93 glass soot is deposited on it, and heated in (B) to vitrify to form the lower layer [SiO 2
₂ ] 92 part is under clad layer 71, upper layer [SiO ₂ + Ge] 9
The three parts become the core layer 21.

Next, the core 2 is patterned to form the core 2 in (C), and this step is performed by referring to FIGS.
As shown in (e), a mask material is deposited on the core layer 21 in (a) to obtain a mask layer 51, and then a photoresist material is applied on the mask layer 51 in (b). Then, a Cr mask 95 is provided with a photoresist layer 94 and the pattern shape is provided in (c).
And the photoresist layer 94 is exposed to light, the photoresist layer 94 is etched to form a pattern in (d), and the mask layer 51 is etched to form the mask 5 in (e). The core layer 21 is etched by the mask 5 in f) to pattern the core 2, and the mask 5 is removed in (g) to complete the core fabrication.

Next, as shown in FIG. 6D, a glass soot of [SiO ₂ ] 92 having a low refractive index is deposited on this, and heated at (E) to vitrify to form the overclad 6. Forming and core 2
An optical waveguide is formed by surrounding glass with a glass having a smaller refractive index.

The above steps are not carried out for each optical waveguide chip 1, but as shown in FIG. 8, the wafers 39 are collectively manufactured in a large amount at a time, and then the wafers 39 are diced along the cutting line 49 for each chip. Cut and make with an ing saw.

The cutting line 49 is made as a boundary line between the optical waveguide chips 1 in the same manner as the core 2 is made.

[0010]

However, since the relative refractive index difference between the core 2 and the overclad 6 is small, the cutting line 49 is difficult to see clearly, and it takes time to set the cutting and there is a risk of missetting. There is. To use the cutting line 49 as the positioning reference line for cutting,
Since it is hard to see, it cannot be made highly precise, and it is dangerous if you do not check it every time you cut, and you can not save labor. There was a problem called.

In view of the above problems, it is an object of the present invention to provide a method for producing a cutting reference line that can be clearly seen and can be set with high accuracy without adding a special processing step.

[0012]

The above object is to provide an optical waveguide chip on a wafer 3 in the production of a ridge type optical waveguide chip wafer as shown in the principle explanatory view of FIG. 1 and FIGS. When manufacturing the core 2 of No. 1, the cutting reference line 4 for cutting the chip is formed on the core 2 outside the region of the optical waveguide chip 1, and the deposition process of the cutting reference line 4 on the upper surface of the core 2 is changed in the same process. This is achieved by the method for producing a cutting reference line of an optical waveguide chip of the present invention, which makes the reflectance of the cutting reference line 4 large. [1] Specifically, when removing the mask 5 on which the core 2 is patterned, the mask 5 is left over the cutting reference line 4 and the overclad 6 is deposited as it is. It is suitable depending on the line making method. [2] Further, a mask 55 for the cutting reference line 44 is formed thicker than the core 5 mask 5 of the optical waveguide chip 1, and the mask 5 of the optical waveguide chip 1 portion is completely removed in a subsequent mask removing step.
The mask 55 of the cutting reference line 44 can be applied by the second cutting reference line manufacturing method of the present invention in which the mask 55 is left by the difference in thickness and the overclad 6 is deposited as it is. [3] Further, when the mask 5 on which the core 2 is patterned is removed and the overclad 6 is deposited, the cutting reference line 45
It is also applicable by the third cutting reference line manufacturing method of the present invention in which the core 2 is covered and the overclad 6 is not deposited on the core 2.

[0013]

That is, as shown in FIGS. 1 (a) and 1 (b), the overclad 6 is always deposited on the upper surface of the core 2 of the optical waveguide chip 1, but the cutting reference line 4 is unclear as it is. Increase the reflectance so that you can see clearly. Therefore, the deposition process on the upper surface of the core 4 of the cutting reference line 4 is changed, and (a)
The reflectance can be increased by providing a reflective layer as described above or by not depositing the overclad 6 as shown in FIG.
It should be noted that these processes can be easily performed by not performing the process of the cutting reference line 4 in a series of process steps for manufacturing the optical waveguide chip 1.

As shown in FIG. 2, such a cutting reference line 4 is provided outside the region of the optical waveguide chip 1 so that the wafer 3 can be aligned with high accuracy, and the first setting is performed once. It's done.

Further, if the cutting reference line 4 remains in the chip as it is and is incorporated therein, the reflective layer forming material may have a bad influence, but since it is provided separately and cut off, there is no problem.

Specifically, in the first method, the deposition process for increasing the reflectance of the cutting reference line 4 is performed by the core 2 as shown in FIG.
When the patterned mask 5 is removed, the mask 5 is left to cover the cutting reference line 4 and the overclad 6 is deposited as it is to form the mask 5 on the reflective layer.

The second method is, as shown in FIG. 4, from the mask 5 for the core 2 of the optical waveguide chip 1 to the mask of the cutting reference line 44.
55 is thickly formed, the mask 5 of the optical waveguide chip 1 portion is completely removed in the subsequent mask removing step, the mask 55 of the cutting reference line 44 is left by the difference in thickness, and the over cladding 6 is deposited as it is. The mask 55 is formed on the reflective layer as described above. The difference in the thickness of the masks 5 and 55 is that
This can be easily performed by providing a photoresist mask once on the overlaid mask layers 51 to change the thickness, or by partially depositing the mask layer 51 twice.

The third method is to remove the mask 5 on which the core 2 is patterned as shown in FIG.
When the core 2 of the cutting reference line 45 is covered, and the overclad 6 is not deposited on that portion, the cutting reference line 45 is formed by exposing the core 2 itself. appear.

Thus, according to the present invention, it is possible to provide a method for producing a cutting reference line which can be clearly seen and can be set with high accuracy without adding a special processing step.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the embodiments shown in the drawings. Throughout the drawings, the same reference numerals denote the same objects. FIG. 2 shows a wafer of one embodiment of the present invention, FIG. 3 shows a manufacturing flow of an embodiment of the first cutting reference line manufacturing method of the present invention, and FIG.
Is a manufacturing flow of an embodiment of the second cutting reference line manufacturing method of the present invention, and FIG. 5 is a manufacturing flow of an embodiment of the third cutting reference line manufacturing method of the present invention.

Each of the present embodiments is applied to the production of a wafer of a ridge type silica-based optical waveguide chip, and as shown in FIG. The optical waveguide chips 1 are formed to have a high density, and four cutting reference lines 4 that are orthogonal to each other with high precision are provided so as to surround the region apart from each other and serve as a reference for each cutting line of the optical waveguide chip 1. There are various methods for producing the cutting reference line 4 as follows.

The first method is applied to the core fabrication of (C) in the manufacturing process of the optical waveguide chip of FIG. 6 of the above-mentioned conventional example, and as shown in detail in FIG. Three
A mask material is applied to the entire surface of the core layer 21 of 1 to a thickness of about 1 μm to form a mask layer 51, and in (b), a photoresist is further applied to form a photoresist layer 94. ), A Cr molding pattern mask 95 for core molding is applied to expose the photoresist layer 94, and (d) is developed for patterning.
The mask layer 51 is etched in (e) to form the patterned mask 5, the core layer 21 is etched in (f) to form the patterned core 2, and the mask 5 is formed in (g). However, at this time, as shown by the dotted line in the figure, the portion of the cutting reference line 4 is adhered and covered with an adhesive tape, and the mask 5
Is removed, and in step (h), a glass soot of SiO ₂ having a low refractive index is uniformly deposited on the entire surface and vitrified to form an overclad 6, which is completed.

As a result, the overclad 6 is directly deposited on the core 2 in the optical waveguide chip 1 region, but the overclad 6 is deposited on the core 2 of the cutting reference line 4 while the mask 5 remains. The mask 5 serves as a reflection layer, the cutting reference line 4 molded by the core 2 can be clearly seen, and the wafer 3 can be set on the cutting machine with high accuracy, and only the first set can be performed.

The second method is as shown in detail in FIG.
The thickness of the mask layer 51 is made thicker in the cutting reference line 44 than in the optical waveguide portion, and the thickness difference is about 1/3 when the mask 55 is removed, and only the cutting reference line 44 is masked. The overclad 6 is deposited while leaving 55 to complete.

The steps of forming the mask layers 51 having different thicknesses are steps (b ') to (e') in the figure, which are added to the first method, but conversely, the mask removal of (g ') is performed. Then, it is not necessary to cover with tape or the like.

The third method is applied to the step (D) of glass soot deposition + vitrification in the manufacturing flow of the optical waveguide chip shown in FIG. 6 of the above-mentioned conventional example, as shown in detail in FIG. After completion of the core 2 in which the mask 5 having the pattern formed in (a) is removed, in (b) the portion of the core 2 of the cutting reference line 45 is covered with an adhesive tape as shown by the dotted line in the figure, and in (c). Except for the covered part, glass soot deposition + vitrification is performed (d)
Remove the cover and complete. This allows the cutting reference line 45
Since the overclad 6 is not deposited on the core 2 of FIG.

The above-mentioned embodiments are merely examples, and the dimensions of each part and the etching method are not limited to those described above.

[0028]

As described above, according to the method for producing a cutting reference line of the present invention, a cutting reference line which can be clearly seen and can be set with high precision can be obtained without adding a special processing step, and the optical waveguide chip can be easily cut. In addition, it can be performed accurately, and further, the wafer can be cut only by the initial positioning setting, improving the chip quality,
It greatly contributes to the automation of production.

[Brief description of drawings]

FIG. 1 is an explanatory view of the principle of the present invention.

FIG. 2 is a wafer according to an embodiment of the present invention.

FIG. 3 is a manufacturing flow of an example of a first cutting reference line manufacturing method of the present invention.

FIG. 4 is a manufacturing flow of an example of a second cutting reference line manufacturing method of the present invention.

FIG. 5: Manufacturing flow of an example of a third cutting reference line manufacturing method of the present invention

FIG. 6 is a flow chart of manufacturing a conventional optical waveguide.

FIG. 7: Conventional example core production flow

FIG. 8 is a conventional example wafer.

[Explanation of symbols]

1 Optical waveguide chip 2 Core 3,
39 Wafer 4,44,45 Cutting reference line 5,55 Mask 6
Overclad 21 Core layer 49 Cutting line 51
Mask layer 71 Under clad layer 91 Si substrate 92
[SiO ₂ ] 93 [SiO ₂ + Ge] 94 Photoresist layer 95
Cr mask

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hideki Isono, 2-chome, Kitaichijo Nishi, Chuo-ku, Sapporo-shi, Hokkaido Inside Fujitsu Hokkaido Digital Technology Co., Ltd. (72) Yoshihiko Kaito Kita-ichijo Nishi, Chuo-ku, Sapporo, Hokkaido 2-chome, Fujitsu Hokkaido Digital Technology Co., Ltd.

Claims (4)

[Claims] 1. When manufacturing a wafer of a ridge type optical waveguide chip, for cutting a chip outside the region of the optical waveguide chip (1) when manufacturing a core (2) of the optical waveguide chip (1) on a wafer (3). The cutting reference line (4) of the cutting reference line (4) was produced by the core (2), and the deposition process on the upper surface of the core (2) of the cutting reference line (4) was changed in the same process to reflect the cutting reference line (4). A method for producing a cutting reference line for an optical waveguide chip, which is characterized in that the production rate is increased. 2. A mask (5) having a patterned core (2).
When removing the mask, cover the top of the cutting reference line (4) with the mask (5).
2. The method for producing a cutting reference line for an optical waveguide chip according to claim 1, wherein the overclad (6) is left as it is, and the overclad (6) is deposited as it is. 3. A mask for a core (2) of an optical waveguide chip (1)
From (5), forming a thick mask (55) of the cutting reference line (44),
The mask (5) of the optical waveguide chip (1) is completely removed in the subsequent mask removing step, and the mask (55) of the cutting reference line (44) is removed.
Is left over by the difference in thickness, and overclad as it is
2. The method for producing a cutting reference line for an optical waveguide device according to claim 1, wherein (6) is deposited. 4. A mask (5) having a patterned core (2).
Is removed, and when the overclad (6) is deposited, the core (2) of the cutting reference line (45) is covered and the overclad (6) is not deposited on that part. The method for producing a reference line for cutting an optical waveguide element according to claim 1.