JP2003307616A - Dielectric multilayer film filter and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a means to improve the yield for fabricating a multilayer film filter which uses a fluorinated polyimide substrate. <P>SOLUTION: After dielectric films are laminated onto a fluorinated polyimide substrate which has enough thickness for self supporting property and is easily handled, the multilayer film side is adhered and fixed to a supporting material, the back face of the polyimide substrate is ground and polished to control to specified thickness, and the film is cut into a chip size from the fluorinated polyimide substrate side. Or, if the substrate bends by the stress of the film after the dielectric layers are formed on the fluorinated polyimide substrate, a resin film such as polyimide is applied on the surface of the dielectric layer so as to reduce the bend and to protect the dielectric layers. Thus, the dielectric multilayer film filter is manufactured in a high yield. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a dielectric multilayer filter having excellent optical characteristics.

[0002]

2. Description of the Related Art As optical communication technology has spread as a basic technology for information communication systems, multilayer filters have become more important as key devices for optical networks, and there is a demand for cost reduction and mass production. .

An optical thin film filter using a resin material as a substrate is expected to be excellent in durability and easy to handle as compared with a glass substrate. Among them, the fluorinated polyimide resin has excellent transmission characteristics in the near infrared region, and also has the highest heat resistance and high strength, and is therefore most suitable as the substrate material of the multilayer filter.

Dielectric multilayer filters using a polyimide substrate are conventionally made of glass or Si (silicon) having a smooth surface.
Thickness of 1 on substrate such as substrate by dipping method or spin coating method
After preparing a polyimide film substrate with a size of 0 to several μm and laminating a dielectric film on it, dicer is used to obtain a predetermined size (0.5 m
After being cut into m × 1 to 2 mm), the base material was removed to prepare. The multilayer filter is often used by inserting it into an optical fiber, and it is necessary to manufacture it as a thin film of about 30 μm including the substrate.

However, in the conventional methods, since the adhesion between the polyimide film and the base material such as glass or Si (silicon) is weak, the filter chip is separated from the base material during cutting by the dicer, and There is a problem that the yield is extremely poor and it is difficult to reduce the cost.

As a method for preventing this, Japanese Patent Laid-Open No. 2000-1
For 80618, the polyimide film substrate prepared on the substrate is once peeled from the base material, and is again attached to another base material using a soft adhesive such as wax, and then the polyimide film is adhered from the polyimide film according to the chip shape. A method is described in which a cut is made up to the middle of a layer, a dielectric is laminated on the cut, and then the adhesive is dissolved with a solvent or the like to form a chip.

However, since the polyimide film is thin in this method, it is difficult to handle, and the dielectric layer and the polyimide film are cracked or broken during the step of peeling from the substrate or the step of re-adhering to the substrate with an adhesive. There is a problem that cracks are likely to occur.

As described above, when manufacturing a dielectric multilayer filter using a polyimide substrate, defects such as scratches and chip cracks are likely to occur in the chip forming process,
A major problem is that it causes a decrease in yield, and improvement of the manufacturing method has been desired.

An object of the present invention is to produce a fluorinated polyimide multilayer filter with a high yield.

[0010]

According to the present invention, a dielectric film is laminated on a fluorinated polyimide substrate having a self-supporting thickness, and then the dielectric multilayer film side is adhered / fixed to a supporting material such as a glass substrate. Then, after the back surface of the fluorinated polyimide substrate is cut and polished, it is cut to the size of the multilayer filter chip from the side of the fluorinated polyimide substrate on which the dielectric multilayer film is not laminated.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a thickness of 0.5 to 1.0 having self-supporting property and surface smoothness that is easy to handle.
A mm fluorinated polyimide substrate for optics is used. There is no problem with the thickness of the substrate if it is easy to handle, but if it is too thick, polishing will take time, and if it is too thin, handling will be difficult, so a thickness of 0.5 to 1.0 mm is suitable. A fluorinated polyimide substrate having this thickness has hitherto been difficult to produce, but recently, a substrate having optical performance and high surface smoothness can be produced and can be obtained. .

FIG. 1 is a view for explaining the manufacturing process of a fluorinated polyimide multilayer filter according to the present invention. A fluorinated polyimide substrate is shown in FIG. This board is IA
FIG. 1B shows a structure in which a dielectric film is stacked by setting it in D (ion-assisted vapor deposition) or a sputtering device. When the polyimide substrate is set in the substrate holder for vapor deposition, the polyimide substrate may be attached to another substrate with a tape or an adhesive to reinforce it. In FIG. 1C, after stacking the dielectric films, an adhesive such as a UV curable resin or a thermosetting resin is used,
The multilayer film side has a smooth glass substrate or Si (silicon)
Adhesive / fixed to a substrate, resin or other supporting material.

In FIG. 1D, the back surface of the polyimide substrate is polished so that the total thickness of the substrate and the multilayer film is 30 μm, for example.
Process to a certain degree.

Next, in FIG. 1 (E), the polyimide substrate together with the supporting material is set in a dicer, and a predetermined chip size (0.
5 mm × 1 to 2 mm), and after cutting, the filter chip is peeled from the support material by UV irradiation, heating, etc. to obtain a product.

After the dielectrics are laminated, if the multilayer film substrate is curved and is difficult to handle due to film stress, the resin layer such as polyimide is thinly formed on the surface of the dielectric layer to correct the curvature. You can do it.

Even if the multilayer substrate is not curved, it is preferable to form a thin resin film such as polyimide on the surface of the dielectric layer because the dielectric layer can be protected.

Resins for correcting the film stress and protecting the dielectric surface include polyimide, fluorinated polyimide, epoxy resin, silicone resin, fluoromethacrylate, and fluorinated epoxy resin with suppressed propagation loss, Deuterated silicone resin, deuterium fluoromethacrylate, etc. are conceivable, but of course other materials may be used as long as they have a small propagation loss at the wavelength required for filter performance.

In the method of the present invention, the polyimide substrate before cutting and polishing has a constant thickness, so that it is easy to handle. Further, since the cutting / polishing step and the chip cutting step after the dielectric layer is laminated are performed from the polyimide side where the multilayer film is not laminated in the state where the dielectric side is adhesively fixed to the support material, peeling of the multilayer film or Film cracks,
A polyimide filter can be obtained in a high yield with less chipping. When cutting the polyimide substrate,
It is possible to cut from the side of the support material to which the multi-layer film is attached, but the fragments of the support such as glass will damage the filter and reduce the yield, so it has more flexibility than these materials. By cutting from the polyimide side which is a thin film, it is possible to improve the yield.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.

[0020]

EXAMPLES Example 1 First, a flat plate-like fluorinated polyimide substrate for optical use (100 mmφ) having a thickness of 1.0 mm and manufactured by a casting method was used.
This substrate is set in the plasma deposition device and the dielectric multilayer film
(About 100 layers, about 20 μm) was deposited by vapor deposition. Then, this vapor deposition surface was bonded to a glass substrate (thickness: 2 mm) having the same diameter with a thermosetting resin adhesive, and the polyimide side was polished with a polishing machine until the total thickness of the polyimide and the dielectric film became 30 μm. . In this state, the whole is set on a dicer, and the polyimide side has a depth of 40μ in a predetermined chip size.
Cut to m. The cutting part is 60mm near the center of the board.
Within the square of the corner, the chip size is 0.5 mm x 2 mm. After that, the chip was peeled off from the glass substrate by heating to obtain a target filter chip.

Visual inspection of the obtained filter chips with a polarizing microscope revealed that out of the total of 3,600 chips, the defective ones were those 25 due to surface scratches, the ones 41 due to peeling of the polyimide and the vapor deposition film, and the chipping of the chips. Thing 193,
104 due to chip breakage or film cracking
The total yield was 363, and the yield rate was 89.9%, which was extremely good.

Example 2 An optical plate-shaped fluorinated polyimide substrate (100 mmφ) having a thickness of 0.5 mm was used.
This substrate was set in an ion assisted sputtering film forming apparatus, and the same dielectric multilayer film (about 100 layers, 20 layers) as in Example 1 was prepared.
(μm) was deposited. Since a slight warpage due to film stress was observed on this substrate, a polyamide varnish was formed on the surface of the multilayer film by a spin coating method and heated to 10
A μm fluorinated polyimide film was formed. As a result, the warpage of the entire substrate is no longer observed. The vapor deposition surface was adhered to a silicon substrate having the same diameter with a thermosetting resin adhesive, and the polyimide side was polished with a polishing machine until the total thickness of the polyimide and the dielectric film became 40 μm. This substrate was cut into a predetermined chip size from the polyimide side to a depth of 50 μm. The cutting portion is within a square of 60 mm square near the center of the substrate, and the chip size is 0.5 mm × 2 mm.
After that, the chip was peeled off from the glass substrate by heating to obtain a target filter chip.

Visual inspection of the obtained filter chip with a polarizing microscope revealed that out of 3,600 chips, defective ones were due to scratches on the surface 13, peeling of the polyimide and vapor deposition film 72, and chipping of the chips. Thing 221,
The total number of 382 chips was 76 due to breakage or film cracking of the entire chip, and the yield rate was 89.4%, which was extremely good.

[Comparative Example 1] Metal Al having a thickness of 200 nm was sputter-deposited on a glass substrate having a diameter of 100 mm and a thickness of 3 mm.
Was deposited. A fluorinated polyimide film having a thickness of 15 μm was formed thereon by baking by spin coating. This substrate was set in a plasma vapor deposition apparatus, and a dielectric multilayer film (about 100 layers, about 20 μm) was formed by vapor deposition under the same conditions as in Example 1. This substrate was set on a dicer and cut from the dielectric film side to a predetermined chip size to a depth of 40 μm. Similar to the embodiment, the cutting portion is within a square of 60 mm square near the center of the substrate, and the chip size is 0.5 mm × 2 mm. After that, this substrate was immersed in 15% hydrochloric acid to dissolve the metal Al, whereby the chip was peeled off from the glass substrate to obtain the target filter chip.

Visual inspection of the obtained filter chips with a polarizing microscope revealed that out of the total of 3,600 chips, defective ones were 240 due to scratches on the surface, 133 due to peeling of the polyimide and the vapor deposition film, and chipping of the chips. Thing 53
1. 52 due to chip breakage or film cracking
4, the total is 1428, and the non-defective rate (yield) is 60.3%.
The value was considerably lower than that of Example 1.

Comparative Example 2 100 mm as in Comparative Example 1
φ, thickness of 3mm glass substrate 200nm by sputter deposition
Was formed into a film of metal Al. A fluorinated polyimide film having a thickness of 15 μm was formed thereon by baking by spin coating. This substrate was set in an ion assisted sputtering film forming apparatus, and the dielectric multilayer film (about 10
0 layer, about 20 μm) was formed. This substrate is set on a dicer and the depth of 40
Cut to μm. Similar to the embodiment, the cutting portion is within a square of 60 mm square near the center of the substrate, and the chip size is 0.
It is 5 mm × 2 mm. After that, this substrate was immersed in 15% hydrochloric acid to dissolve the metal Al, whereby the chip was peeled off from the glass substrate to obtain the target filter chip.

Visual inspection of the obtained filter chip with a polarizing microscope revealed that out of 3,600 chips, defective ones were 228 due to scratches on the surface, 207 due to peeling of the polyimide and the deposited film, and chipping of the chips. Thing 61
7, 73 due to chip breakage or film cracking
5, the total is 1787, and the non-defective rate (yield) is 50.4%.
The value was lower than that of Example 2.

[0028]

EFFECTS OF THE INVENTION In a filter based on fluorinated polyimide, after laminating a dielectric film on a substrate having a thickness that is easy to handle, the back surface of the substrate is cut and polished to adjust to a predetermined thickness, and then fluorinated. By cutting from the polyimide substrate side, a dielectric multilayer filter is manufactured with good yield.

[Brief description of drawings]

FIG. 1 is a diagram showing steps of manufacturing a multilayer filter by the method of the present invention.

[Explanation of symbols]

1 Fluorinated polyimide substrate 2 Dielectric multilayer film 3 Glass substrate 4 Multi-layer filter chip

Continued front page    F-term (reference) 2H048 GA04 GA09 GA26 GA30                 4F100 AK17B AK49B CB001 CB02                       EH66 EJ273 EJ343 GB41                       GB56 JG05A JJ03 JK01                       JM02A JN00

Claims (3)

[Claims] 1. A dielectric multilayer film is laminated on the surface of a self-supporting fluorinated polyimide substrate, and then the dielectric multilayer film side is adhered and fixed to a supporting material, and the dielectric multilayer film is not laminated. , The back side of the fluorinated polyimide substrate is cut and polished to thin the fluorinated polyimide substrate, and then
A method for manufacturing a dielectric multilayer filter, which is characterized by cutting into a chip size. 2. A method of manufacturing a dielectric multilayer filter, wherein when cutting a fluorinated polyimide substrate having a dielectric multilayer film laminated on the surface, the dielectric multilayer film is not laminated, and the fluorinated polyimide substrate is cut from the back surface. Method. 3. A dielectric multilayer film filter manufactured by the method according to claim 1.