JPH1164629A - Optical element and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve long-term reliability of an optical element by forming an intermediate film between a polyimlde film and a dielectric multilayered film so as to improve adhesion property of these layers. SOLUTION: A temporary base body 11 consists of a glass substrate 11a as a temporary substrate and a fluorinated polyimide film 11b formed thereon. A multilayered film 13 comprising alternately deposited SiO2 films and TiO2 films as a dielectric multilayered film is formed to total 20 to 30 μm thickness on the surface of the temporary base body 11 by sputtering. A specified coupling agent (OPI coupler) as an adhesion improving agent is applied on the dielectric multilayered film 13 by spin coating. Then the coupling agent is heat treated in air to form an intermediate film 15 to improve adhesion property between the dielectric multilayered film 13 and a polyimide film to be formed in the succeeding process. Then a polyimide film 17 as a substrate is formed on the obtd. sample. Further, a dicing tape 19 as a supporting body in the succeeding dividing process is fixed on the polyimide film 17. Then the sample is diced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical device using a polyimide film as a substrate and having a dielectric multilayer film on the polyimide film, and a method for manufacturing the same.

[0002]

2. Description of the Related Art For example, Japanese Patent Laying-Open No. 4-211203 discloses an optical element (actually, an optical filter) in which a substrate is formed of a polyimide film and a dielectric multilayer film is provided on the polyimide film. ing. According to the technology disclosed in this publication, an optical element required for optical communication and the like, which is disposed in a minute gap in an optical path and has a thickness of about several tens μm, can be easily manufactured. Can be realized.

According to the technique disclosed in Japanese Patent Application Laid-Open No. 4-211203, the optical filter is manufactured as follows.

First, on a temporary substrate such as a glass substrate,
A liquid polyimide film forming material is applied. Next, the material is dried and cured to form a polyimide film.
Next, a dielectric multilayer film is formed on the polyimide film by, for example, an ion assisted vapor deposition method. Since the polyimide film has excellent heat resistance, it can withstand an increase in temperature when a dielectric multilayer film is formed. Next, a cut corresponding to the planar shape required for the optical element is formed so as to reach the temporary substrate from the surface of the dielectric multilayer film. Next, the polyimide film and the dielectric multilayer film are separated from the temporary substrate in a shape corresponding to the cut. Accordingly, an optical filter using a dielectric multilayer film, which is thin, can be obtained.

[0005]

However, in the conventional optical element (optical filter), the adhesion between the polyimide film and the dielectric multilayer film has not always been satisfactory.

More specifically, the inventor of the present application uses a dicing saw to cut the above-mentioned cuts into a structure comprising a temporary substrate, a polyimide film and a dielectric multilayer film in order to mass-produce the optical device. As a result, it was found that during dicing, there was a problem that the temporary substrate and the polyimide film were peeled off, or that the dielectric multilayer film itself was partially peeled off from the polyimide film (see a comparative example described later). .

A simple method of peeling the temporary substrate from the polyimide film is a method of immersing a structure composed of the temporary substrate, the polyimide film, and the dielectric multilayer film in water. It has been found that a problem occurs in that the dielectric multilayer film itself partially peels off from the polyimide film during the immersion treatment (see a comparative example described later).

[0008] The problem that the temporary substrate and the polyimide film are separated from each other or the dielectric multilayer film itself is separated as described above reduces the production yield of the optical device. Is not preferable in terms of long-term reliability of the optical element.

[0009] The present application has been made in view of such a point, and an object of the present application is to provide an optical device having excellent adhesion between a polyimide film and a dielectric multilayer film, and to provide such an optical device in a simple manner. And a manufacturing method capable of being manufactured.

[0010]

Therefore, according to the invention of the optical device of this application, in an optical device comprising a polyimide film as a substrate and a dielectric multilayer film on the polyimide film,
An intermediate film is provided between the polyimide film and the dielectric multilayer film to improve the adhesion between them.

According to the optical device of the present invention, the adhesion between the polyimide film and the dielectric multilayer film is improved by the provision of the intermediate film, as compared with the case where the intermediate film is not provided. Therefore, the long-term reliability of the optical element can be improved.

Further, according to the invention of the method for manufacturing an optical device of this application, when manufacturing an optical device having a dielectric multilayer film on a polyimide film, (a) a temporary layer which is peeled off in the subsequent process Forming a dielectric multilayer film on the ground; (b) treating the surface of the formed dielectric multilayer film with an adhesion improver for a polyimide film; and (c) treating with the adhesion improver. Forming a polyimide film on the completed dielectric multilayer film, and (d) removing the temporary base from the dielectric multilayer film, which is performed after the step of forming the polyimide film. It is characterized by.

According to the invention of the method for manufacturing an optical element, a dielectric multilayer film is first formed on a temporary base. Next, the surface of the dielectric multilayer film is treated with an adhesion improving agent, and thereafter, a polyimide film as a substrate is formed on the dielectric multilayer film. Therefore, the polyimide film serving as the substrate and the dielectric multilayer film serving as the optical element can be laminated with better adhesion than before. The temporary base can be peeled off at any time. From these facts, it is possible to suppress a decrease in yield due to peeling of the dielectric multilayer film at the stage of manufacturing the optical element, and to realize an optical element having excellent reliability.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of each invention of this application will be described below.

The inventions of this application can be applied to various optical devices using a polyimide film as a substrate and having a dielectric multilayer film as an optical element on the polyimide film.

Specific examples of such an optical element include, but are not limited to, an optical filter, a light reflecting element, and a polarizer.

The polyimide film as the substrate is not particularly limited as long as it does not impair the optical characteristics required for the optical device. For example, Japanese Unexamined Patent Application Publication No.
Various polyimide films including a non-fluorinated polyimide film, such as the fluorinated polyimide film disclosed in Japanese Patent Publication No. 3 (JP-A) No. 3 can be used.

When a fluorinated polyimide film is used, as disclosed in JP-A-4-211203,
A substrate having a refractive index close to that of glass and high transparency in a wide wavelength band can be obtained. In the case of using a fluorinated polyimide film, according to the teaching of Japanese Patent Application Laid-Open No. 4-211203, the fluorine content is 10 to 30% from the viewpoint of obtaining a refractive index close to that of glass and a high transmittance in a wide wavelength range. It is preferable to use a fluorinated polyimide film as described above. On the other hand, the fluorinated polyimide film has poor adhesion to inorganic materials. However, in each invention of this application, since the adhesion between the polyimide film and the dielectric multilayer film can be improved, it is particularly effective for a polyimide film having poor adhesion to the dielectric multilayer film such as a fluorinated polyimide film.

Further, the dielectric multi-layer film is formed, for example, as disclosed in
In the case where the polyimide film is formed by the ion assisted vapor deposition method as disclosed in Japanese Patent Application Laid-Open No. 11203, it is preferable that the polyimide film has a thermal expansion property smaller than that of the dielectric multilayer film. This is because an optical element with less warpage can be easily obtained as disclosed in Japanese Patent Application Laid-Open No. 4-211203.

Further, an intermediate film provided between the polyimide film and the dielectric multilayer film in order to improve the adhesion between them is as follows:
There is no particular limitation as long as the adhesion can be improved and the optical characteristics of the optical element are not impaired.

However, it is preferable that the intermediate film is a film formed by using an OPI coupler (trade name) manufactured by Hitachi Chemical Co., Ltd. At least when the OPI coupler is used, it has been confirmed that the adhesion between the polyimide film and the dielectric multilayer film can be improved to a practically acceptable level without impairing the optical characteristics required for the optical element. (See Examples described later).

Alternatively, it is considered that a film formed using a so-called silane coupling agent frequently used as an adhesion enhancer may be used as the intermediate film. Although the composition is not clear, it is considered that a film formed using a coupler called “Semicofine” manufactured by Toray Industries, Inc. may be used as the intermediate film.

The dielectric multilayer film is made of a material, a film thickness and the number of layers selected according to the specifications required for the optical device.

Next, an embodiment of a component unique to the invention of a method for manufacturing an optical element will be described.

The temporary base is not particularly limited as long as a dielectric multilayer film having a desired film quality can be formed and can be peeled off from the dielectric multilayer film later. However, considering the convenience of confirming the optical characteristics at the time when the formation of the dielectric multilayer film is completed, for example, those having high transparency with respect to the wavelength to be used in the optical element are preferable.

Examples of the temporary base include, for example, a plate of an organic polymer material having a flat surface, or a structure composed of a temporary substrate and a layer of the organic polymer material formed thereon. As an example of the latter, a structure including a temporary substrate and a polyimide film formed thereon can be cited. In this case, it is preferable to use a fluorinated polyimide film as the polyimide film. As described above, since the fluorinated polyimide film does not have such high adhesion to both the temporary substrate and the dielectric multilayer film, the temporary underlayer can be easily removed later from the dielectric multilayer film.

Here, as the temporary substrate when the temporary base includes the temporary substrate, typically, glass, for example, BK
-7 glass or quartz glass.

Further, as a method for forming the dielectric multilayer film, a suitable method such as an evaporation method (including an ion-assisted evaporation method) and a sputtering method can be used.

As a method of treating the dielectric multilayer film with the adhesion enhancer, for example, a method of applying the adhesion enhancer on the formed dielectric multilayer film by a spin coating method (spin coating method), or a method of treating the formed dielectric multilayer film Any suitable method such as a method of spraying the adhesion enhancer on the body multilayer film or a method of immersing the sample on which the dielectric multilayer film has been formed in a liquid of the adhesion enhancer can be used. In that case, a suitable heat treatment is typically performed later. Of course, the heat treatment may not be performed in some cases.

The formation of a polyimide film serving as a substrate is typically performed by applying a coating solution for forming a polyimide film on a dielectric multilayer film that has been treated with an adhesion enhancer by a spin coating method. A method of obtaining a polyimide film by heating and curing is used.

As a method of removing the temporary base, any suitable method can be used, but a method of immersing the sample in water is particularly preferable in terms of mass productivity.

In carrying out the invention of the method for manufacturing an optical element, from the viewpoint of mass productivity, a laminate including a dielectric multilayer film and a polyimide film is formed on a temporary base by the procedure of the present invention. It is preferable to adopt a method in which the laminate is divided in a plane and each of the divided portions is used as an optical element. In such a case, during the step of forming the polyimide film and the step of removing the temporary base, the laminated film including the polyimide film and the dielectric multilayer film is divided into two planes to separate individual optical elements. When obtaining, a step of fixing a support for supporting these optical elements on the polyimide film is performed, and thereafter (preferably after the temporary base (at least the temporary substrate when the temporary substrate is included) is removed). It is preferable to perform a step of dividing the laminated film.

Here, as the support, a so-called dicing tape can be used if the above dividing step is a step using a dicing saw.

In the dividing step according to this preferred embodiment, the handling when the laminated body including the dielectric multilayer film and the polyimide film is put into the dividing step and the handling of each optical element after the division is performed well. be able to.

[0035]

EXAMPLES Examples of each invention of this application will be described below together with comparative examples. This description will be made with reference to the drawings. However, the drawings used in the description merely schematically show the dimensions, shapes, and arrangements of the components so that the present invention can be understood. Also, in each of the drawings, the same components are denoted by the same reference numerals, and duplicate description may be omitted.

1. Example FIGS. 1A to 1D and FIGS. 2A to 2C are process diagrams illustrating a procedure for manufacturing an optical element according to an example. Both are diagrams shown by schematic side views.

In this embodiment, the temporary base 11 is composed of a glass substrate 11a as a temporary substrate and a fluorinated polyimide film 11b formed thereon.

For this purpose, a polyamic acid (trade name: OPI-2005) manufactured by Hitachi Chemical Co., Ltd. as a polyimide film forming material is applied to the glass substrate 11a to a predetermined thickness by a spin coating method. Next, this is heat-treated in a nitrogen atmosphere at a temperature of 70 ° C. for 2 hours, further at a temperature of 160 ° C. for 1 hour, further at a temperature of 250 ° C. for 0.5 hour, and further at a temperature of 350 ° C. for 1 hour. As a result, a temporary base 11 having a fluorinated polyimide film 11b having a thickness of 10 μm is obtained on the glass substrate 11a (FIG. 1).
(A)).

Next, on the surface of the temporary base 11, an alternate multilayer film 13 of a SiO ₂ film and a TiO ₂ film is formed as a dielectric multilayer film by sputtering to have a total thickness of 20 to 30.
It is formed to have a thickness of μm (FIG. 1B).

Next, a coupling agent (trade name: OPI coupler) manufactured by Hitachi Chemical Co., Ltd. is applied as an adhesion improving agent on the dielectric multilayer film 13 by a spin coating method.
Next, this is heat-treated in air at a temperature of 100 ° C. for 0.5 hour and further at a temperature of 250 ° C. for 0.5 hour. Thus, it is considered that an intermediate film 15 for improving the adhesion between the dielectric multilayer film 13 and a polyimide film to be formed later is generated (FIG. 1C).

Next, a polyimide film 17 as a substrate is formed on the sample (FIG. 1D). Here, the polyimide film 17 is formed under the same conditions as the above-described polyimide film 11b.

Next, a dicing tape 19 serving as a support in a later dividing step is fixed on the polyimide film 17 (also FIG. 1D).

Next, this sample is immersed in water. When the sample is immersed in water, the sample is generally separated at the interface between the temporary substrate 11a and the polyimide film 11b (FIG. 2).
(A)). In some cases, separation may occur at the interface between the polyimide film 11b and the dielectric multilayer film 13. On the other hand, the dielectric multilayer film 13 and the polyimide film 17 serving as the substrate are firmly adhered to each other due to the action of the intermediate film 15, and no separation occurs at the interface between them.

Next, the polyimide film 11b, the dielectric multilayer film 13, the intermediate film 15, the polyimide film 17, and the support 19
Is set in a dicing machine. Next, the sample is diced by a dicing saw 21 so as to obtain a 1 mm square optical element (FIG. 2).
(B)).

This dicing is performed while pouring cooling water onto the surface of the sample as in the case of ordinary dicing. Temporary groundwork 11
The polyimide film 11b which was a part of the
However, the polyimide film 11b is peeled off during the dicing. On the other hand, peeling between the dielectric multilayer film 13 and the polyimide film 17 as a substrate was not recognized at all.

After dicing, the respective optical elements 23 comprising the polyimide film 17, the intermediate film 15, and the dielectric multilayer film 13 are peeled off from the dicing tape 19 as a support to obtain the target optical element 23 (FIG. 2 ( C)). An optical element could be manufactured with a yield of 100% regarding the adhesion at the interface between the polyimide film 17 and the dielectric multilayer film 13.

2. Comparative Example Next, a comparative example will be described with reference to FIGS. Here, FIG. 3 is a process chart for explaining a procedure for manufacturing the optical element of the comparative example.

A glass substrate 31a is prepared as a temporary substrate. Then, on the temporary substrate 31a, a fluorinated polyimide film 31b serving as a substrate in the case of the comparative example is formed under the application conditions and the heat treatment conditions at the time of forming the polyimide film 11b in the example (FIG. )).

Next, a dielectric multilayer film 13 is formed on the polyimide film 31b under the same conditions as in the embodiment (FIG. 3B).

Next, this sample is set in a dicing machine and diced under the same conditions as in the embodiment (FIG. 3).
(C)).

Each chip obtained by dicing is transferred to the temporary substrate 3
Each chip is immersed in water in order to obtain an optical element 33 by separating each at the interface between 1a and the polyimide film 31b (FIG. 3 (D)).

The optical device of the comparative example is manufactured by the procedure as described above. However, in the case of the comparative example, a defect in which the temporary substrate 31a and the polyimide film 31b are separated during dicing, a defect in which separation occurs at the interface between the dielectric multilayer film 13 and the polyimide film 11b, or a case where the chip is It was found that about 80 out of 100 chips were peeled off at the interface between the dielectric multilayer film 13 and the polyimide film 11b during immersion. That is, it was found that the yield in the manufacturing method of the comparative example was only 20%.

[0053]

As is clear from the above description, according to the invention of the optical device of this application, an optical device having better adhesion between the dielectric multilayer film and the polyimide film as the substrate than before can be obtained. An optical element having excellent long-term reliability is realized.

Further, according to the invention of the optical element manufacturing method of this application, a polyimide film can be formed as a substrate on the dielectric multilayer film with good adhesion, so that the manufacturing process and the dielectric multilayer after product completion are completed. Peeling of the film itself from the polyimide film is less likely than in the past. Therefore, it is possible to manufacture an optical device using a polyimide film as a substrate and having a dielectric multilayer film on the polyimide film with a high yield.

[Brief description of the drawings]

FIG. 1 is a manufacturing process diagram for explaining a manufacturing method according to an embodiment.

FIG. 2 is a manufacturing process diagram following FIG. 1 for explaining the manufacturing method of the example.

FIG. 3 is a manufacturing process diagram illustrating a manufacturing method of a comparative example.

[Explanation of symbols]

 11: Temporary base 11a: Temporary substrate 11b: Polyimide film 13: Dielectric multilayer film 15: Intermediate film 17: Polyimide film (substrate) 19: Support 21: Dicing saw 23: Optical element 31a: Temporary substrate 31b: Polyimide film ( 33: Optical element of comparative example

Continuation of front page (72) Inventor Noriyoshi Yamada 1-3-1 Gotenyama, Musashino City, Tokyo Inside NTT Advanced Technology Corporation

Claims (4)

[Claims] 1. An optical device comprising a polyimide film as a substrate and a dielectric multilayer film on the polyimide film, comprising an intermediate film between the polyimide film and the dielectric multilayer film for improving the adhesion between the two. An optical element characterized by the above-mentioned. 2. A method for manufacturing an optical device comprising a polyimide film as a substrate and a dielectric multilayer film on the polyimide film, wherein a dielectric multilayer film is formed on a temporary base which is peeled off in a later process. And a step of treating the surface of the formed dielectric multilayer film with an adhesion improving agent for a polyimide film, and on the dielectric multilayer film treated with the adhesion improving agent,
A method for manufacturing an optical element, comprising: a step of forming a polyimide film; and a step of removing the temporary base from the dielectric multilayer film, which is performed after the step of forming the polyimide film. 3. The method for manufacturing an optical element according to claim 2, wherein the method is performed between the step of forming the polyimide film and the step of removing the temporary base, and includes the polyimide film and the dielectric multilayer film. A step of fixing a support for supporting these optical elements on the polyimide film when obtaining the individual optical elements by dividing the laminated film in a plane, and the step of fixing the support is performed after the step of fixing the support; A method of manufacturing the optical device, further comprising a step of dividing the laminated film. 4. The method for manufacturing an optical element according to claim 2, wherein a structure including a temporary substrate and a polyimide film laminated thereon is used as the temporary base. Method.