JP3414350B2 - Method of manufacturing master mold for optical element - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding die for manufacturing an optical component mainly used for optical communication by a molding method.
The present invention relates to a master mold for producing a mold and a method for manufacturing an optical element.

[0002]

2. Description of the Related Art In recent years, optical communication has made remarkable progress and has come into practical use in CATV, computer networks and the like. However, for widespread use including FTTH, it is required to solve problems such as drastic cost reduction, mass production and miniaturization of optical components.

For example, an optical mounting circuit board using an optical waveguide has been proposed for integration and miniaturization of an optical transceiver. This is a technique in which a quartz optical waveguide having a desired function is formed on a silicon substrate, and a metal electrode is further wired to mount a semiconductor element or an electric circuit. Optical fibers are arranged in an array by a V-groove guide. An optical module is constructed by connecting the thus-formed one to an optical waveguide (for example, Japanese Patent Laid-Open No. 60940/1993 or Japanese Patent Laid-Open No. 27/1990).
No. 410, etc.).

By using the optical waveguide as described above, an integrated and miniaturized optical module can be realized.

However, these optical modules have a problem in terms of cost.

One is that the optical waveguide is expensive. Optical waveguides are manufactured using semiconductor processes such as flame deposition method, film formation by CVD, core patterning by photolithography, dry etching, etc., but because the chip size is relatively large, cost reduction effect can be achieved even in mass production. I can't expect.

Another problem is that the connection cost between the optical waveguide and the optical fiber is high. As shown in FIG. 7, the substrate on which the optical waveguide is formed and the substrate on which the guide groove for fixing the optical fiber is formed are independent and separated from each other.

In FIG. 7, 71 is a silicon substrate, 72 is an optical waveguide, 73 is an optical fiber, 74 is a V groove block, 75 is a laser diode, 76 is a photodiode, and 77 is an electric circuit pattern.

In order to suppress the optical loss between the optical fiber and the optical waveguide, it is necessary to adjust, assemble and fix the position within ± 1 μm in the case of the single mode. These optical axis adjustments are currently carried out in a system equipped with an automatic adjustment mechanism for many axes, which poses a serious problem in terms of mass productivity and economical efficiency. Further, selective wet etching of a silicon substrate and a grinding method of various substrates are used for the production of the V-grooves, which have drawbacks of poor mass productivity and poor reproducibility of the groove shape.

As a method for solving this problem, a groove for fixing the fiber and a groove corresponding to the core of the optical waveguide are formed by using press molding which has already been put into practical use as a method for manufacturing an aspherical glass lens, and the groove is used for the core. A method for forming an optical waveguide by embedding a core material such as resin in the groove is disclosed in Japanese Patent Laid-Open No. 7-28
It is proposed in Japanese Patent No. 7141. In this method, for example, as shown in FIG. 8, a mold having an uneven shape corresponding to a fiber fixing portion and an optical waveguide portion is pressed against a workpiece and the inverted shape thereof is transferred. For the fiber fixing guide and the optical waveguide, Grooves can be mass-produced with good shape reproducibility.
Here, 81 is an optical fiber guide groove forming part, and 82
Is an optical waveguide pattern forming part.

By embedding a core material such as resin in the groove for the optical waveguide, the groove can be made to function as an optical waveguide, and the relative position of the groove for the fiber and the groove for the optical waveguide can be accurately transferred by copying the shape of the optical fiber. It is possible to easily and optically connect the optical fiber and the optical waveguide with high efficiency without any special position adjustment simply by arranging them in the groove.

[0012]

When transferring an optical waveguide having a fine structure by press molding, obtaining a mold becomes a problem.

In the case of a single mode, the optical waveguide has a rectangular cross section with a width and a depth of about several microns, so it has been difficult to machine it with high precision. It has been proposed so far to form an optical waveguide pattern on a mold by using dry etching (for example, Japanese Patent Laid-Open No. 11-21).
8631).

However, although dry etching is excellent in processing precision of minute shapes, it is difficult to process the dimensions of several tens to several hundreds of microns, and it is difficult to process the shapes having a large dimensional difference. In addition, since the photolithography and vacuum processes are frequently used, the mold production efficiency is not high,
The manufacturing cost of the optical component is increased accordingly.

On the other hand, when the optical waveguide pattern is processed by wet etching, an undercut (a phenomenon in which the lower part of the mask is shaved and thinned) occurs, so that the rectangular cross section necessary for the optical waveguide cannot be obtained.

A single mode optical fiber has a diameter of 12
It is about 5 microns, and the dimensional difference is 10 times or more that of an optical waveguide of about several microns. For this reason, there is a problem that it is difficult to fabricate a mold having the above-mentioned fiber fixing portion and a portion corresponding to the core of the optical waveguide at the same time only by dry etching.

From the above, it is necessary to make full use of different processing methods such as machining the optical fiber fixing portion and dry etching the optical waveguide molding portion. However, in performing such different processing methods, if the optical waveguide and the optical fiber are single mode, the connection accuracy is ± 1.
Since it is less than μm, there is a problem that the die machining is extremely severe in order to ensure its accuracy, the die becomes expensive, and mass production cannot be performed.

[0018]

In order to achieve the above object, a method for manufacturing a master mold for optical elements according to the first aspect of the present invention is provided .
The optical fiber guide part on the first member by grinding.
The second member is provided on a part of the first member, and
The second member is ground to a predetermined thickness, and the second member is polished.
Optical waveguide pattern by photolithography and etching
Is formed .

[0019]

[0020]

[0021]

[0022]

[0023]

As the second method for producing a master mold for optical elements, an optical fiber guide portion is formed on a mold member by grinding, the mold member is partially and selectively coated with a thin film, and the coated portion is formed. Is characterized by forming an optical waveguide pattern by photolithography and etching. According to these first and second methods, an optical waveguide pattern and an optical fiber guide section are provided,
In addition, it becomes possible to manufacture a master mold having extremely high relative accuracy. Using the obtained master mold,
It is possible to obtain molding dies for optical elements by performing molding.
it can. According to this, the cost of the mold, and
Can significantly reduce the cost of optical elements molded by
it can.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) FIG. 1 shows the configuration of a master type for optical elements according to the first embodiment of the present invention. This is intended for single-mode optical waveguides and optical fibers, and the core of the optical waveguide pattern is approximately 10
An optical waveguide groove pattern 11 having a micron width and a depth is provided, and an optical fiber guide groove 12 having a V-shaped cross section is formed adjacent to the optical waveguide groove pattern 11.

A method of manufacturing the master die for optical elements shown in FIG. 1 will be described with reference to FIGS. Here, an example in which quartz glass is used for the master type is shown.

First, the first master mold manufacturing method will be described with reference to FIG.

(A) The optical fiber guide groove 22 is formed on the quartz glass substrate 21 with a grinding wheel having a V-shaped cross section.
In the figure, the number of grooves is one, but several tens can be processed without problems. Grinding machines for performing such processing are commercially available, and the groove pitch accuracy can be adjusted to ± 0.5 μm or less by controlling the temperature. Regarding the V-shape, the angle of V does not matter, but when the optical fiber is arranged as shown in FIG. 4, the V-shape is such that the core center of the optical fiber is above the surface of the quartz glass substrate.

(B) Next, another quartz glass substrate 23 is directly bonded to a part of the V-groove processed portion. Here, the direct bonding is to bond the surfaces of the substrates to each other without using a bonding member after the surfaces of the substrates are hydrophilized. The connection interface is strongly bonded mainly by hydrogen bond of hydroxyl group and covalent bond of oxygen atom.

(C) The quartz glass substrate 23 is polished to a predetermined height with respect to the quartz glass substrate 21. The height at this time will be described later.

(D) Photolithography and dry etching are performed only on the quartz glass substrate 23 to form an optical waveguide pattern.
The groove 24 is formed. Regarding the height of the quartz glass substrate by polishing in (c), when the optical fiber is arranged in the optical fiber guide groove 22, the height between the center of the optical fiber and the center of the optical waveguide pattern groove is within ± 1 μm. It is polished to a height such that Further, the horizontal position of the optical waveguide pattern groove 24 on the quartz glass substrate 23 needs to be ± 1 μm, but the horizontal positioning adjustment can be performed by the photomask alignment during photolithography.

As a result, the master mold for optical elements of the present invention is completed.

Next, the second master mold manufacturing method will be described with reference to FIG.

(A) An optical fiber guide groove 32 having a V-shaped cross section is formed in a quartz glass substrate 31 by the same method as the first manufacturing method.

(B) Next, a thin film is deposited on a portion of the V-groove processed portion to fill the V-groove portion and the quartz glass substrate 31.
The terrace 33 is provided by forming a step higher than the surface. Examples of the coating method at this time include a flame deposition method, a CVD method, a vacuum deposition method, and a sputtering method for a quartz material. Further, if necessary, after the film is formed, annealing at 1000 ° C. may be performed.

(C) The terrace 33 is used as in the first manufacturing method.
Is ground to a predetermined height. The height of the terrace 33 is the same as that described in the first manufacturing method.

(D) The terrace 33 as in the first manufacturing method.
The optical waveguide pattern 34 is formed by performing photolithography and dry etching on only this.

As a result, the master mold for optical elements of the present invention is completed.

A master mold for optical elements can be obtained by using the above-described two manufacturing methods.

Regarding the material of the optical waveguide pattern portion, in addition to the quartz glass described above, crystallized glass,
It is possible to accurately dry-etch diamond, DLC, sapphire, silicon, etc. to a depth of several microns. Alternatively, it is also possible to obtain a master mold by a LIGA process using a material that can be plated such as nickel.

The optical fiber guide groove portion is preferably made of the same material as that of the optical waveguide pattern portion, but it can be ground and is kept at about 600 ° C. when forming a mold for an optical element. Any material that can withstand temperature may be used, and cemented carbide, cermet, various ceramics, etc. may be used.

The optical fiber guide groove is not limited to the V shape, but may be a rectangle, a semicircle, a trapezoid, or the like.

When this master mold is used for molding a material made of a glass material, platinum (Pt), osmium (Os), iridium (Ir), rhodium (R) is formed on the press surface.
h), rhenium (Re), ruthenium (Ru), tantalum (Ta), and tungsten (W) can be coated with a protective film to prevent deterioration of the die press surface during molding. it can. Further, when such a protective film is used, peeling of the protective film can be prevented by providing an intermediate layer containing an element contained in the mold or the protective film between the mold and the mold.

Further, in the first master type manufacturing method, the substrates are directly joined to each other, but the present invention is not limited to this, and an adhesive layer may be used, for example. When the adhesive layer is used, it is necessary to maintain the connection between the substrates within the heating temperature range when forming the mold for the optical element.

(Second Embodiment) A second embodiment of the present invention will be described below with reference to the drawings.

First, a method of manufacturing a molding die for an optical element using the obtained master die will be described.

In FIG. 5, 51 is a mother glass and 52
Is a master mold for optical elements, 53 is a lower mold, 54 is a heater block, and 55 is a molding chamber.

As shown in FIG. 5, a mother glass 51 containing a nucleating agent is set in a molding chamber 55, the above-mentioned master mold 52 is set oppositely, and an inert gas flow such as nitrogen or argon is set. Alternatively, the mother glass is softened by heating under vacuum. The heating temperature is around the softening temperature of glass (400 to 550 ° C.). After that, the glass is molded by the master mold 52, then cooled and the glass is taken out. Next, the taken out glass is put into a high temperature furnace and heated under a flow of an inert gas such as nitrogen or argon or under vacuum. The temperature at this time is 600 ° C. or higher.
Then, it is cooled to room temperature to crystallize the glass.

As a result, a mold having an inverted shape of the master mold can be manufactured. In this manufacturing method, the glass size shrinks by about several percent during crystallization, so the master mold is prepared in consideration of this. Alternatively, in order to avoid a dimensional change, the glass may be crystallized by performing molding by a master mold in a molding machine, heating to a high temperature while being pressurized, and then cooling. In this case, it is possible to obtain a molding die with almost no dimensional change from the master die. A mold made of crystallized glass is not only capable of transferring a complicated shape by molding in this way, but also has extremely high mechanical strength and is very effective for molding fine shapes such as optical waveguide patterns. is there.

The nucleating agent contained in the mother glass is titanium (Ti), zirconia (Zr), iron (F).
e), oxides, sulfides, fluorides, or platinum (Pt), gold (Au), silver containing any one element of vanadium (V), nickel (Ni), chromium (Cr) and lithium (Li) If it is (Ag), the molding die manufacturing method described above is effective.

The mold thus obtained has a shape as shown in FIG. In FIG. 6, 61 is an optical fiber guide groove forming portion, and 62 is an optical waveguide pattern forming portion.

It is difficult to realize such a shape by machining or etching, and the manufacturing method described in this embodiment is very effective. In addition, by producing a molding die for an optical element using molding by a master die,
The mold can be obtained at a very low cost, and as a result, the optical element can be manufactured at a low cost.

The shape of the master die does not necessarily have to be the same as that of the target optical element because the degree of dimensional change varies depending on the molding conditions of the molding die and the annealing conditions during crystallization. . The shape of the master mold is determined according to the molding process and annealing conditions.

With respect to the molding die, the material of the optical element molded using the molding die does not matter. For example, any material that is softened by heat, such as resin or glass, may be used. Also, like the master mold, when used to mold materials made of glass-based materials,
Platinum (Pt), Osmium (Os), Iridium (Ir), Rhodium (Rh), Rhenium (Re),
By coating a protective film containing at least one of ruthenium (Ru), tantalum (Ta), and tungsten (W) as a main component, deterioration of the die press surface during molding can be prevented. Further, when such a protective film is used, the adhesion strength of the protective film can be increased by providing an intermediate layer containing an element contained in the mold or the protective film between the mold and the mold. The peeling of the film can be prevented.

(Embodiment 3) Using the optical element molding dies manufactured in the above-described embodiment, in the same manner as in Embodiment 2, a heated and softened substrate is used for the optical element. An optical element can be obtained by pressing and pressing the molding die to transfer the inverted shape of the molding die for optical elements to the base material.

As described above, if the master die is used to form the molding die and the molding die is used to form the optical element, the optical element can be manufactured very efficiently. It goes without saying that it is useful not only for the simultaneous molding of the optical waveguide pattern and the optical fiber guide described in the present embodiment but also for all optical elements that require a shape with a large dimensional difference.

Further, in the master die and the molding die of the present invention, the press surface may have the above-mentioned material and constitution, and the other die constituent parts may be made of other materials.

In the present embodiment, the single mode optical waveguide, the molding die for the optical fiber, and the master die are described. The present invention is particularly effective for the single mode, but the multimode or the plastic is used. It is also effective for optical fibers.

Although the optical waveguide pattern shape has been described by using the example of the rectangular groove, it is effective regardless of the uneven shape.

The optical element molding die can also be manufactured by using the LIGA process although the cost is high, in addition to the method described in this embodiment.

[0062]

As described above, the master type of the present invention
Resulting in the production process therefore the master type, to the use of this
Optical elements having a much more complicated surface shape can be obtained in large quantities and at low cost. In particular, a minute shape such as an optical waveguide and an optical fiber guide having a size larger than that by one digit or more can be collectively molded with high accuracy.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a master type for an optical element of the present invention in a first embodiment of the present invention.

FIG. 2 is a diagram showing a manufacturing process of a first master die for an optical element according to the first embodiment of the present invention.

FIG. 3 is a diagram showing a manufacturing process of a second master die for an optical element according to the first embodiment of the present invention.

FIG. 4 is a cross-sectional view showing a positional relationship between an optical fiber core and a V groove that is an optical fiber guide groove in the first embodiment.

FIG. 5 is a schematic cross-sectional view of a molding machine used when manufacturing the optical element molding die according to the second embodiment by molding.

FIG. 6 is a configuration diagram of a molding die for an optical element of the present invention in a second embodiment.

FIG. 7 is a configuration diagram of a conventional general optical mounting circuit board.

FIG. 8 is a configuration diagram showing an example of a molding die that simultaneously molds an optical fiber fixing groove and an optical waveguide groove.

[Explanation of symbols]

11,24,34 Optical waveguide groove pattern 12, 22, 32 Optical fiber guide groove 21, 31 Quartz glass substrate 23 Unprocessed quartz glass substrate 33 Terrace (Quartz material thin film) 51 mother glass 52 Master type for optical element of the present invention 53 Lower mold 54 heater block 55 Molding room 61 Optical fiber guide groove forming part 62 Optical Waveguide Pattern Forming Section 71 Silicon substrate 72 Optical waveguide 73 optical fiber 74 V groove block 75 Laser diode 76 photodiode 77 electric circuit pattern 81 Optical fiber guide groove forming part 82 Optical Waveguide Pattern Forming Section

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mikihiro Shimada 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Hidenao Kataoka 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. In-company (56) Reference JP-A-7-113924 (JP, A) JP-A-7-287141 (JP, A) JP-A-9-292542 (JP, A) JP-A-8-292332 (JP, A) ) JP-A-11-157851 (JP, A) JP-A-10-139450 (JP, A) JP-A-8-133761 (JP, A) JP-A-7-218739 (JP, A) JP-A-8- 304645 (JP, A) JP 11-218631 (JP, A) JP 2-254404 (JP, A) JP 63-250609 (JP, A) JP 2000-121870 (JP, A) US Patent 5343544 (US, A) A. Rogner et. al. , Mass assembly of passive polymer multimode and single e-mode waveguide de devices, 1994 Optical Fiber Communicance Technology. 279-280 A. Neyer et. al. , Electronics Letters, February 18, 1993, Vol. 29 No. 4, pp. 399-401 (58) Fields surveyed (Int.Cl. ⁷ , DB name) G02B 6/12-6/14 G02B 6/30 C03B 11/00-11/16

Claims (2)

(57) [Claims] 1. An optical fiber guide portion is formed on a first member by grinding, a second member is provided on a part of the first member, and the second member is polished to a predetermined thickness. A method of manufacturing a master die for an optical element, comprising forming an optical waveguide pattern on the second member by photolithography and etching. 2. An optical fiber guide portion is formed on the mold member by grinding, and the thin film is partially and selectively coated on the mold member so that a part of the optical fiber guide portion is embedded and the height is higher than the surface of the mold member. A method of manufacturing an optical element master mold, comprising forming a terrace, then polishing the terrace to a predetermined thickness, and performing photolithography and etching on the terrace to form an optical waveguide pattern.