JP2002082245A - Method for manufacturing optical wiring layer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the loss caused by the crack and air bubbles generated in core patterning by dry etching in a method for manufacturing an optical wiring layers having cores and clads. SOLUTION: The optical wiring layer is manufactured by the method including a process step of forming the first clad layer and the core layer on at a base, a process step of relieving the internal stress in the first clad layer and the core layer, a process step of forming the core patterns by using dry etching and a process step of forming the second clad having the core patterns.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing an optical wiring layer.

[0002]

2. Description of the Related Art In order to make a computer capable of performing arithmetic processing faster, the clock frequency of a CPU tends to increase more and more, and a clock frequency of the order of 1 GHz has come to the present. As a result, there is a portion where a high-frequency current flows in the electric wiring made of copper on the printed circuit board in the computer, so that malfunction occurs due to generation of noise, and electromagnetic waves are generated, which adversely affects the surroundings. It will also be.

In order to solve such a problem, a part of copper electric wiring on a printed circuit board is replaced with an optical fiber or an optical waveguide and an optical signal is used instead of an electric signal. I have. This is because, in the case of an optical signal, generation of noise and electromagnetic waves can be suppressed.

[0004] From the viewpoint of high-density mounting or miniaturization, optical and optical wiring are stacked on the same substrate.
It is desirable to make an electrical wiring board. For example, as described in JP-A-3-29905, there has been proposed a substrate in which an optical fiber is fixed on an electric wiring substrate with an insulating film. However, when an optical fiber is used as the optical wiring, due to the limit of its flexibility, it cannot cope with an optical wiring having a complicated shape, and the degree of freedom in design is reduced.
There is a problem that it is impossible to cope with high-density wiring or downsizing of a substrate.

[0005] For this reason, several configurations of optical / electrical wiring boards using so-called optical waveguides have been proposed as optical wirings on electrical wiring boards. The configuration of the optical waveguide is such that a core pattern through which an optical signal propagates is embedded in a cladding layer that confine the optical signal to the core pattern. Here, the method of forming the core pattern is to form a metal mask or a resist mask by a photolithography technique,
A method of manufacturing by dry etching is generally used. According to this method, the optical wiring can be formed based on the pattern of the photomask, so that the degree of design freedom is increased. Also,
It is possible to cope with transmission over a relatively short distance.

However, particularly in the case of an optical waveguide using a polymer material, internal stress sometimes remains in the cladding layer. For this reason, when a core pattern is formed by dry etching, there may be a problem that the internal stress concentrates on the etched portion and a crack occurs.
The cracks may cause air bubbles to form when forming the second cladding that covers the core pattern, and the air bubbles may cause an increase in loss.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned drawbacks of the prior art, and has as its object to suppress cracks generated during dry etching.

[0008]

In order to achieve the above object, the present invention is directed to a method for manufacturing an optical wiring layer having a core and a clad, comprising the steps of: And a step of forming a core layer, a step of relaxing internal stress of the first clad layer and the core layer, a step of forming a core pattern using dry etching, and a step of forming a second clad covering the core pattern. And a method for manufacturing an optical wiring layer. According to a second aspect of the present invention, in the optical wiring layer according to the first aspect, the first cladding layer and the core layer are separated from the support as the step of relaxing the internal stress of the first cladding layer and the core layer. It is a manufacturing method of. Claim 3
The present invention is the method for manufacturing an optical wiring layer according to any one of claims 1 to 2, wherein a polymer is used as a material for forming the first cladding layer. A fourth aspect of the present invention is the method for manufacturing an optical wiring layer according to the third aspect, wherein polyimide is used as the polymer.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for manufacturing an optical wiring layer according to claims 1 to 4 of the present invention will be described with reference to FIGS.

<Factors of Crack Generation> First, the causes of cracks will be described with reference to FIG. When the first clad layer 2 and the core layer 3 formed on the support 1 and having the remaining internal stress are dry-etched (a), the stress concentrates on the corners 4 formed by the dry etching. (B), and a crack 5 is generated therefrom (c). When the internal stress remains due to a difference in thermal expansion coefficient between the substrate and the first cladding layer and the core layer, or due to volume expansion or shrinkage when forming the first cladding layer and the core layer. and so on.

[0011] Therefore, when fabricating an optical wiring layer, it was possible to prevent the occurrence of cracks by relaxing the internal stress before performing dry etching. Hereinafter, FIG.
The method will be described in detail with reference to FIG.

<Formation of First Cladding Layer and Core Layer> First, the first cladding layer 6 is formed (a). Preferably, the first cladding layer 6 is formed on a rigid support 7. The thickness of the first cladding layer 6 is 3 to 1000 μm
Although the degree is preferable, it is not limited to this range. As a method for forming the first cladding layer 6, for example, a rigid support 7 such as a silicon wafer or glass is coated with a polymer material by spin coating or casting,
Thereafter, a method such as curing can be used.

Next, a core layer 8 is formed on the first cladding layer 6 (b). The thickness of the core layer 8 is 3 to 100 μm
Although the degree is preferable, it is not limited to this range. As a method for forming the core layer 8, for example, a method in which a polymer material is coated on the cladding layer 7 formed on the support 6 by spin coating and then cured.

<Relieving the internal stress of the first cladding layer and the core layer> Next, the internal stress of the first cladding layer 6 and the core layer 8 is relaxed (c). The method of relaxing the internal stress of the first cladding layer 6 and the core layer 8 is not particularly limited as long as it is a method capable of relaxing the remaining internal stress. A method of peeling the one clad layer 6 and the core layer 8 can be used. Examples of the method for peeling include, but are not limited to, a method of immersing in a remover, for example, a method of etching and removing a base such as a metal provided in advance, and a method of performing heat treatment.

<Patterning of Core by Dry Etching> Further, a core pattern 9 is formed by dry etching (d). As a mask for patterning, a mask obtained by etching a metal thin film or the like may be used, or a resist having high resistance to dry etching may be used. The formation of the mask pattern may be performed before the internal stress is relaxed, or may be performed after the internal stress is relaxed.

<Formation of Second Cladding> Finally, after removing the mask pattern, the second cladding 10 is formed to cover the core pattern 9 and obtain the optical waveguide layer 11 (e). The thickness of the second clad is 3 to 1
The thickness is preferably about 000 μm, but is not limited to this range.

[0017]

The present invention will be described below with reference to specific examples. Note that the present invention is not limited to the embodiments described below.

<Embodiment> An embodiment will be described with reference to FIG. The first cladding layer 6 was formed on the support 7 by spin-coating polyimide OPI-N3305 (manufactured by Hitachi Chemical Co., Ltd.) and imidizing (FIG. 2).
(A)). As the support, a silicon wafer on which aluminum was deposited was used.

On top of this, polyimide OPI-N3405
A core layer 8 was formed by spin-coating (manufactured by Hitachi Chemical Co., Ltd.) and imidizing (see FIG. 2B).

Next, a silicon-containing resist was applied on the core layer 8 and exposed and developed. The resist pattern thus formed was used as a dry etching mask.

Next, the first cladding layer 6 and the core layer 8 were once peeled off from the silicon wafer by etching away aluminum (see FIG. 2C).

This was dry-etched by oxygen RIE to form a core pattern 9 (see FIG. 2D).
Thereafter, the silicon-containing resist was stripped.

On top of this, polyimide OPI-N3305
(Hitachi Kasei Kogyo Co., Ltd.) was spin-coated and imidized to form a second cladding layer 10 covering the core pattern 9 to complete the optical wiring layer 11 (FIG. 2E).
reference).

<Conventional Example> Polyimide OPI-N3305 (manufactured by Hitachi Chemical Co., Ltd.) is spin-coated on a support 7 (using a silicon wafer) and imidized to form a first clad layer 6 ( FIG. 3A).

On top of this, polyimide OPI-N3405
Core layer 8 was formed by spin-coating (manufactured by Hitachi Chemical Co., Ltd.) and imidizing (see FIG. 3B).

Next, a silicon-containing resist was applied on the core layer, and was exposed and developed. The resist pattern thus formed was used as a dry etching mask (not shown). This was dry-etched by oxygen RIE to form a core pattern 9 (FIG. 3C).
reference). At this time, cracks 12 were formed along the pattern.
Thereafter, the silicon-containing resist was stripped.

On top of this, polyimide OPI-N3305
The second clad layer 10 was formed by spin coating and imidizing (manufactured by Hitachi Chemical Co., Ltd.), and the optical wiring layer 11 was completed (see FIG. 3D). At this time, the cracks remained as bubbles 13.

[0028]

As can be understood from the above description, the present invention has the following effects.

By performing a relaxation step for releasing the stress once before performing the dry etching, a crack generated at the time of the dry etching can be suppressed. As a result, it is possible to prevent an increase in loss caused by chewing the bubbles.

[0030]

[Brief description of the drawings]

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is an explanatory diagram showing crack generation factors which are problems to be solved by the present invention.

FIG. 2 is an explanatory view showing a method for manufacturing an optical wiring layer according to the present invention.

FIG. 3 is an explanatory view showing a conventional method for manufacturing an optical wiring layer.

[Description of Signs] 1 support 2 first cladding layer 3 core layer 4 corner portion formed by dry etching 5 crack 6 first cladding layer 7 support 8 core layer 9 core pattern 10 second cladding layer 11 optical wiring layer 12 crack 13 bubble

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Atsushi Sasaki, Inventor 1-5-1, Taito, Taito-ku, Tokyo Inside Toppan Printing Co., Ltd. (72) Inventor Hatsune Hara 1-5-1, Taito, Taito-ku, Tokyo Letterpress F Term in Printing Co., Ltd. (Reference) 2H047 PA02 PA24 PA28 QA05

Claims (4)

[Claims] 1. A method of manufacturing an optical wiring layer having a core and a clad, comprising: forming a first clad layer and a core layer on a support; and relaxing internal stress of the first clad layer and the core layer. A method of forming a core pattern using dry etching; and a step of forming a second clad that covers the core pattern. 2. The method of manufacturing an optical wiring layer according to claim 1, wherein the step of relaxing the internal stress of the first cladding layer and the core layer includes separating the first cladding layer and the core layer from the support. Method. 3. The method for manufacturing an optical wiring layer according to claim 1, wherein a polymer is used as a material for forming said first cladding layer. 4. The method according to claim 3, wherein polyimide is used as said polymer.