CN1206841A - Production method of optical waveguide device - Google Patents

Abstract

The present invention provides a method for producing optical waveguide device in absence of external biasing of electrode, wherein the optical waveguide device includes an upper cover layer, optical waveguide and a lower cover layer. The method has following steps: (a) forming a lower cover layer on the plate substrate, (b) forming a optical waveguide layer on the lower cover layer, (c) forming a upper cover layer on the optical waveguide layer, (d) forming a predetermined optical waveguide image, (e) etching the upper cover layer and the optical waveguide layer according to the optical waveguide image, (f) forming material layer on the structure formed by etching. As a result damage of the optical waveguide and effect of outside force are reduced.

Description

Production method of optical waveguide device

The present invention relates to a method of producing an optical waveguide device, and more particularly to an optical waveguide device which does not require external bias such as electrodes on the basis of conventional methods.

Many optical waveguide devices have been formed on planar substrates by using planar waveguide technology, and high integration of such devices has been studied. In general, optical waveguide devices are fabricated using semiconductor production techniques or micro-electromechanical systems (MEMS) techniques.

1A to 1F describe a conventional method of manufacturing an optical waveguide device. In a conventional method of producing an optical waveguide device, first, as shown in FIG. 1A, a cladding layer 110 is deposited on a planar substrate 100, and a core layer 140 for forming a waveguide is deposited as shown in FIG. 1B. Then, as shown in FIG. 1C, the core layer 140 is masked with the waveguide pattern, and a mask pattern 150 for the waveguide is formed by performing photolithography and etching. Then, the core layer 140 is etched to form the waveguide 130 as shown in FIG. 1D . Here, reference numeral 170 denotes an etched region. After the waveguide is produced, the mask pattern 150 is removed as shown in FIG. 1E , and then the upper cladding layer 160 is formed as shown in FIG. 1F , thereby completing the fabrication of the optical waveguide device.

The conventional methods of manufacturing optical waveguides described above present no particular practical problems and have been used up to the present. However, without strictly following the steps of the conventional method described above, it is easy to fabricate devices that can operate without external biases such as electrical signals or heat. Also, because the waveguide is sufficiently exposed during production, it is easily damaged.

In order to solve the above-mentioned problems, an object of the present invention is to provide a method of producing an optical waveguide device, which does not require external biasing such as electrodes, wherein the degree of exposure when forming the waveguide is minimized, so that damage to the waveguide is reduced , and no additional steps for removing external stress after forming the waveguide are required.

Correspondingly, in order to achieve the above object, a method for producing an optical waveguide device is provided, wherein the optical waveguide device has a lower cladding layer, an optical waveguide and an upper cladding layer, and the method includes the following steps: (a) A lower cladding layer is formed on the planar substrate; (b) an optical waveguide layer is formed on the lower cladding layer, which has a higher refractive index than the lower cladding layer; (c) an upper cladding layer is formed on the optical waveguide layer, which has a higher refractive index than the optical waveguide layer. low refractive index of the waveguide layer; (d) forming a predetermined optical waveguide pattern on the upper cladding layer; (e) etching the upper cladding layer and the optical waveguide layer according to the optical waveguide pattern; A material layer of the same material as the overcladding.

Preferably, the material forming the lower cladding layer is the same as that of the substrate, and the lower cladding layer, the optical waveguide layer and the upper cladding layer are formed by spin coating as an optical polymer having low transmission loss at an operating wavelength. Also, the structure formed after depositing each of the lower cladding layer, the optical waveguide layer, and the upper cladding layer is heated to improve film quality.

Preferably, the step (d) of forming a predetermined optical waveguide pattern includes the following steps: (d1) forming a material film on the upper cladding layer, which has stronger dry erosion resistance than the optical waveguide layer; (d2) forming a material film on the upper cladding layer Deposit photoresist; (d3) calibrate the photomask with optical waveguide pattern on the structure formed in step (d2) and expose photoresist through photomask ultraviolet; (d4) process photoresist in developing solution developing a photoresist pattern; and (d5) forming a mask pattern as an optical waveguide pattern by dry etching the material film, using the photoresist pattern as an etching mask.

Similarly, step (d) also includes the following steps: (d11) depositing a photoresist on the upper cladding layer; (d21) aligning a photomask having a predetermined optical waveguide pattern with the structure formed in step (d11), and UV exposure of the photoresist through a photomask; (d31) processing the photoresist in a developing solution to develop a photoresist pattern; (d41) depositing a metal film on the photoresist and the upper cladding layer; and (d51) A mask pattern as an optical waveguide pattern is formed by immersing the structure obtained in the sub-step (d41) in an organic solvent for removal.

Preferably, in etching step (e) the lower cladding layer is partially or completely etched. Likewise, in the step (e) of forming the material layer after etching, the material layer may also be formed by a spin coating method or a soaking method.

Objects and advantages of this invention will be more clearly understood by referring to the accompanying drawings and detailed description of a preferred embodiment. in:

1A to 1F describe a conventional method of producing an optical waveguide device; and

2A to 2F depict a method of producing an optical waveguide according to a preferred embodiment of the present invention.

Optical polymers used in waveguides according to the invention have low transmission loss at optical wavelengths. Such an optical polymer, having a high refractive index difference ([Delta]n) of more than 0.3% compared to the cladding, is used as a polymer for waveguides. A method of producing an optical waveguide using such an optical polymer according to the present invention will be described below.

A flat substrate 200 having good surface flatness such as a silicon substrate or glass is used as the substrate shown in FIG. 2A. A lower cladding layer 210 is formed on the substrate 200 . Here, a material having a lower refractive index than the waveguide and having optical transparency at an operating wavelength is used as the lower cladding layer 210 . The lower cladding layer 210 is deposited by a spin coating method used in semiconductor production. Preferably, the thickness of the formed lower cladding layer 210 is about 20 μm. After deposition, the resulting structure is dried to improve film quality. The material constituting the lower cladding layer 210 may be the same as that of the substrate 210 .

As shown in FIG. 2B, the optical polymer used for the waveguide has low transmission loss and a refractive index difference (Δn) greater than 0.3% compared with the lower cladding layer 210, and is deposited to the lower cladding layer by a spin-coating method. 210, thereby forming a core layer 240. After deposition, drying is performed to improve film quality. Here, the core layer 240 is formed to have a thickness of about 7 μm.

Then, as shown in FIG. 2C , the upper cladding layer 220 is spin-coated onto the core layer 240 with the same polymer as the lower cladding layer 210 . Here, the optimum thickness of the upper cladding layer is about 20 μm. According to a preferred embodiment of the present invention, the lower cladding layer 210 shown in FIG. 2C , the core layer 240 having a higher refractive index than the lower cladding layer 210 and the upper cladding layer 220 are sequentially stacked on the substrate 200 .

FIG. 2D depicts the step of forming a mask pattern 250 for fabricating the waveguide pattern. The material used for the mask pattern is polymer, metal, silica or silicon, which have stronger dry etching resistance than the core layer 240 . Likewise, metal thin films made of chromium (Cr) can also be used in the release process.

The step of forming the mask pattern 250 by dry etching shown in FIG. 2D will be described below. First, a 300-500 angstrom thick silicon dioxide film, polymer is deposited on the upper cladding layer 220 by a vacuum deposition method such as sputtering, E-beam and thermal evaporation method. After depositing the photoresist (PR) by the spin coating method, a patterned photomask is aligned with the substrate and then selectively irradiated with ultraviolet rays onto the deposited deposited photoresist (PR). Then, the PR is dipped in a developing solution for developing to form a PR pattern, and then the resulting structure is dry-etched using the PR pattern as an etching mask to form a mask pattern 250 .

On the other hand, a mask pattern can be formed by the following lift-off method. First, PR is deposited on the upper cladding layer 200 by a spin-coating method, a patterned photomask is aligned with the substrate, and ultraviolet (UV) rays are selectively irradiated onto the deposited PR, and then, the PR is immersed in a developing solution Used for imaging to form PR graphics. A metal film containing Cr is deposited on the formed structure by a vacuum deposition method such as sputtering, E-beam, or thermal evaporation method, and then immersed in an organic solvent such as acetone for detachment, thereby forming a mask for the waveguide. Film Graphics 250.

After completing the steps described in FIG. 2D , vertical etching is performed on the upper cladding layer 220 and the core layer 240 . When _O2 plasma is supplied to the top of the substrate under vacuum, the portion with the mask pattern 250 is not etched by the plasma and the portion without the mask pattern 250 is etched by the plasma. During the etching process, the etching depth to the core layer 240 which will become the waveguide 230 need not be precisely controlled. That is, the lower cladding layer 210 may be partially etched. Figure 2E shows a case where the lower cladding layer 210 is partially etched vertically to form a waveguide region. Here, reference numeral 270 denotes an etched portion, reference numeral 280 denotes an etched lower cladding layer, and 290 denotes an etched upper cladding layer.

FIG. 2F depicts the final step of depositing the same polymer used for the lower cladding layer 210 to form cladding layer 260 on the etched structure of FIG. 2E by spin-coating or dipping methods, and then thermally treating the resulting structure to complete the optical waveguide. device. In this step, the cladding can be deposited without removing the mask pattern 250, so that the influence of external force on the waveguide can be eliminated.

In the method of producing an optical waveguide device according to the present invention, which does not require external placement such as electrodes, it can be easily produced on the basis of conventional methods. Also, exposure of the waveguide is minimized during production, thereby reducing damage to the waveguide.

By the production method according to the present invention, when producing a device, it is possible to operate without an external bias such as an electric signal or heat, the process can be smoothly performed, and the exposure of the waveguide is minimized. Thus, any damage to the waveguide during production can be reduced.

Also, there is no need to perform additional steps to remove external forces affecting the waveguide after producing the waveguide device.

Claims (19)

1, a kind of production has the method for the fiber waveguide device of under-clad layer, optical waveguide and top covering, it is characterized in that this method comprises following steps:

(a) on planar substrates, form under-clad layer;

(b) on under-clad layer, form light waveguide-layer with refractive index lower than under-clad layer;

(c) forming the top covering that formation has the refractive index lower than light waveguide-layer on the light waveguide-layer;

(d) on top covering, form predetermined optical waveguide figure;

(e) according to optical waveguide figure etching top covering and light waveguide-layer; And

(f) on the structure that etching forms, form the material layer that has same material with top covering.

2, method according to claim 1 is characterized in that, the material that wherein forms under-clad layer is identical with substrate.

3, method according to claim 1 is characterized in that, under-clad layer, light waveguide-layer and top covering are formed by the optic polymer that has low loss in the operating wave strong point.

4, method according to claim 2 is characterized in that, under-clad layer, light waveguide-layer and top covering are formed by the optic polymer that has low loss in the operating wave strong point.

5, method according to claim 1 is characterized in that, under-clad layer, light waveguide-layer and top covering pass through spin-on deposition.

6, method according to claim 2 is characterized in that, under-clad layer, light waveguide-layer and top covering pass through spin-on deposition.

7, method according to claim 4, it is characterized in that also being included in every layer of deposition after the oven dry resulting structures to improve the step of film quality.

8, method according to claim 1 is characterized in that step (d) also comprises following steps:

(d1) on top covering, form the material film of the anti-dry corrosion stronger than light waveguide-layer;

(d2) on material film, deposit photoresist;

(d3) be aligned in the photomask that has the optical waveguide figure on step (d2) resulting structures and also pass through photomask UV-exposed photoresist;

(d4) in developing-solution, handle photoresist with video picture photoresist figure; And

(d5) utilize photoresist figure as etching mask to form mask pattern by the dry etching material film as the optical waveguide figure.

9, method according to claim 2 is characterized in that step (d) also comprises following steps:

(d1) on top covering, form the material film of the anti-dry corrosion stronger than light waveguide-layer;

(d2) on material film, deposit photoresist;

(d3) be aligned in the photomask that has the optical waveguide figure on step (d2) resulting structures and also pass through photomask UV-exposed photoresist;

(d4) in developing-solution, handle photoresist with video picture photoresist figure; And

(d5) utilize photoresist figure as etching mask to form mask pattern by the dry etching material film as the optical waveguide figure.

10, method according to claim 8 is characterized in that having that than light waveguide-layer the material film of stronger anti-dry corrosion to be arranged be to select from the combination that film constituted by polymkeric substance, metal, silicon dioxide and silicon.

11, method according to claim 9 is characterized in that having that than light waveguide-layer the material film of stronger anti-dry corrosion to be arranged be to select from the combination that film constituted by polymkeric substance, metal, silicon dioxide and silicon.

12, method according to claim 1 is characterized in that step (d) comprises following steps:

(d11) on top covering, deposit photoresist;

(d21) photomask and the formed structural alignment of step (d11) that will have predetermined optical waveguide figure also passes through photomask UV-exposed photoresist;

(d31) in imaging liquid, handle photoresist with video picture photoresist figure;

(d41) depositing metal films on photoresist and top covering; And

(d51) form mask pattern by the formed structure of substep (d41) being immersed the organic solvent that is used for breaking away from as the optical waveguide figure.

13, method according to claim 2 is characterized in that step (d) comprises following steps:

(d11) on top covering, deposit photoresist;

(d21) photomask and the formed structural alignment of step (d11) that will have predetermined optical waveguide figure also passes through photomask UV-exposed photoresist;

(d31) in imaging liquid, handle photoresist with video picture photoresist figure;

(d41) depositing metal films on photoresist and top covering; And

(d51) form mask pattern by the formed structure of substep (d41) being immersed the organic solvent that is used for breaking away from as the optical waveguide figure.

14, method according to claim 12 is characterized in that metallic film is made of chromium (Cr).

15, method according to claim 13 is characterized in that metallic film is made of chromium (Cr).

16, method according to claim 1 is characterized in that in the step (e), and under-clad layer is by partially or completely etching.

17, method according to claim 2 is characterized in that in the step (e), and under-clad layer is by partially or completely etching.

18, method according to claim 1 is characterized in that forming after etching in the step (f) of material layer, forms material layer by spin coating method or immersion method.

19, method according to claim 2 is characterized in that forming after etching in the step (f) of material layer, forms material layer by spin coating method or immersion method.

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