JP2000304956A - Manufacture of optical waveguide device, and optical waveguide device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an optical waveguide device which has practically a small optical connection loss and is easily manufactured. SOLUTION: In the manufacture of the optical waveguide device having an optical connection structure between an optical waveguide composed of a core 6 and clad layers 4, 5, and 8 and an optical element formed on a platform, a core end part is positioned nearby the end part of a flat surface of the platform 3 when the core 6 of the optical waveguide is patterned and after an upper clad layer 8 is formed, an end surface is formed by etching the flat part of the upper clad layer 8 where the influence of a projection of the core 6 is eliminated to guide light in and out of the core 6 through the upper clad layer 8. Consequently, the etching time needed to form the end surface of the optical waveguide is shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing an optical waveguide device and an optical waveguide device, and more particularly to a method for manufacturing an optical waveguide device having an optical connection structure between an optical waveguide and an optical element.
And an optical waveguide device having an optical connection structure between an optical waveguide and a fiber.

[0002]

2. Description of the Related Art In order to reduce the size and performance of an optical waveguide device having a planar optical waveguide and to reduce the cost, a light emitting element such as a laser diode and a light receiving element such as a photodiode are mounted on a substrate having an optical waveguide. It is essential to mount it on Therefore, in order to align the position of the active layer of the laser diode with the waveguide core formed on the substrate at the same height, a platform formed on the silicon (Si) substrate has a function as a heat sink of the laser diode. Has been made. In this method, a Si substrate is anisotropically etched using an etchant such as an alkali to form a substrate having a structure in which a part of a platform portion is selectively left, and a quartz optical waveguide is formed thereon. In many cases, a laser diode is mounted on this platform and electric wiring is performed. When mounting the laser diode on the platform, the core and the upper cladding layer surrounding the core are etched perpendicular to the substrate surface just before the laser diode installation position to form vertical walls, and the light from the laser diode is applied to the core. It is configured to introduce a signal (for example, the document “Hybrid optical integration technology using PLC, Electronics Science, July 1995
Moon, pages 97-100 ").

[0003] In an optical connection structure between an optical waveguide and a fiber, Si is generally used to fix the optical fiber.
If a V-groove of the substrate is adopted and a V-groove is formed, S
Anisotropic etching is used in which the surface of the i-substrate has a crystal plane of (100) and the wall of the V-groove is a (111) plane. The part stops just before this inclination and 30 to 30 from the end of the optical waveguide core.
Since the optical connection loss cannot be reduced to 0.2 dB or less as it is, the concave portion having a vertical wall on the Si substrate is cut out by dicing saw or dry-etched at the junction between the optical waveguide and the optical fiber. Grooves were provided (for example, see JP-A-1-12666).
No. 08).

[0004]

A practical target of the optical connection loss at the connection with the optical waveguide is about 0.2 dB or less. In the conventional optical connection structure between the optical waveguide and the optical element, in which the vertical wall is formed in the core and the upper cladding layer, the optical connection loss can be suppressed sufficiently, but it is necessary to etch the quartz film including the core. It takes time to etch the mask material because the mask material is thicker, the quartz film etching time is longer, and
There is a problem that the etching accuracy varies. Further, in the conventional structure in which a concave groove having a vertical wall is provided in an optical connection structure between an optical waveguide and a fiber, the optical connection loss can be suppressed sufficiently, but the concave groove is formed by a dicing saw. Therefore, there is a problem that it is not suitable for mass production and requires a long time by dry etching. Accordingly, an object of the present invention is to provide a manufacturing method capable of obtaining an optical waveguide device with a relatively short etching time, and furthermore, an optical waveguide device whose optical connection loss is sufficiently small for practical use and which is easy to manufacture. Is to provide.

[0005]

According to the first aspect of the present invention,
The present invention relates to a method for manufacturing an optical waveguide device for performing optical connection between an optical waveguide and an optical element, comprising a substrate having a platform on which the optical element is mounted, and a lower cladding layer laminated on a predetermined region excluding the platform of the substrate. And a step of producing a substrate laminate including the platform and a height-adjusting cladding layer laminated on the lower cladding layer. Forming a core having one end near the end of the flat surface of the platform by forming a core layer on the substrate laminate and etching and patterning the core layer; . further,
There is a step of vertically removing the entire upper cladding layer and at least a part of the height adjusting cladding layer on the platform by leaving a partial region near the end of the core. According to the first aspect of the present invention, an optical waveguide device having a structure in which an optical element is mounted on a platform of a substrate and light enters and exits from a core through the upper cladding layer by the steps including these steps. Is produced. According to this manufacturing method, since the upper clad layer covering the core is removed after the end of the core pattern, the film thickness to be etched when forming the end face of the waveguide is reduced. The required etching time can be reduced. According to this manufacturing method, although the end of the optical waveguide and the end of the optical element are separated from each other, the optical connection loss can be suppressed to a practically sufficient level. According to the second aspect of the present invention, the V end having an inclined surface at the end of the groove.
A grooved substrate, an optical waveguide formed of a lower cladding layer, a core, and an upper cladding layer, extending in the longitudinal direction of the V-groove and formed on the substrate; and an optical fiber fixed to the V-groove. The present invention relates to an optical waveguide device having an optical waveguide device, wherein an optical waveguide is provided such that an end of the optical waveguide and an end of the optical fiber face each other in a region of an inclined surface at an end of a V-groove. And
An end of the optical waveguide is provided with a cladding region of an upper cladding layer which surrounds the end with a two-dimensional lens shape such as an arc shape. According to this configuration,
Due to the lens effect, even if the distance between the optical waveguide and the optical fiber core is equal to the inclination of the SiV groove, no excessive loss is generated, so that the optical connection loss can be suppressed to a practically sufficient level.
Cutting with a conventional dicing saw becomes unnecessary,
Manufacturing becomes easier.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a first embodiment of the present invention will be described with reference to FIGS. FIGS. 1 to 3 are process explanatory views showing an embodiment of the manufacturing method of the present invention. The optical waveguide device here has an optical connection configuration between an optical waveguide and an optical element. In this embodiment, first, FIG.
As shown in FIG. 1A, a mirror-polished Si substrate 1 having a (100) crystal surface is used to form a 200 nm SiO2 layer 2 on the front and back surfaces of the Si substrate 1 by thermal oxidation. ), A 10% aqueous solution of hydrofluoric acid (H
F aqueous solution) using an ordinary photolithography process.
Unnecessary portions of the second layer 2 are removed and patterned. Next, using the patterned SiO2 layer 2 as a mask, the Si substrate 1 is anisotropically etched at 80 [deg.] C. in an 80% KOH aqueous solution at 25 [deg.] C. Then, as shown in FIG.
The layer 2 is dissolved with an aqueous HF solution to form a platform 3 for mounting a laser diode. Next, as shown in FIG. 1 (D), the entire surface of the Si substrate 1 is subjected to plasma CVD to deposit TEOS (tetraethoxysilane) + O2 gas into C2 gas.
Mixed with F6 gas, refractive index is 1.4510 and thickness is 3
After forming a lower cladding layer 4 of SiO2 having a thickness of 0 [mu] m, unnecessary SiO2 above the platform 3 in the lower cladding layer 4 is removed by polishing as shown in FIG.

Next, as shown in FIG. 1 (F), 4.5 μm SiO 2 is formed by a plasma CVD method under the same conditions as the formation of the lower cladding layer 4 so that the position of the active layer of the laser diode and the position of the active layer are determined. A height adjusting cladding layer 5 for adjusting the height of the waveguide core layer is formed on the lower cladding layer 4 including the platform 3. Next, as shown in FIG. 1 (G), a core layer 6 having a thickness of 8 μm is formed only by TEOS (tetraethoxysilane) + O 2 gas, and then, as shown in FIG. 1μm thick α
The -Si film 7 is formed using an RF sputtering apparatus using an Ar gas and a Si target. Next, as shown in FIG. 1 (J), an organic resist pattern is formed on the α-Si film 7 using a normal photolithography technique, and is formed into a waveguide shape using HBr gas by a reactive ion etching method. Process. At this time, the pattern of the α-Si film 7 is set so that its end ends near the end of the platform 3, and the α-Si film 7 on the platform 3 is etched away. The organic resist is removed by ashing with O2 plasma.

Next, as shown in FIG. 2K, using the α-Si film 7 of the optical waveguide pattern as a mask, C 2 F 6 +
The core layer 6 is patterned by C2H4 gas by a reactive ion etching method so that the cross-sectional shape becomes perpendicular to the waveguide shape.
Remove with F6 gas. In this process, platform 3
Is formed near the end of the core 6. Next, FIG.
As shown in (L), the upper cladding layer 8 having a thickness of 15 μm
Under the same conditions as the formation of the lower cladding layer 4,
Then, as shown in FIG. 2M, a WSix film 9 is formed to a thickness of 1 μm on the entire surface of the upper cladding layer 8 by a sputtering method. Next, as shown in FIG. 2 (N), a resist pattern is formed by a normal photolithography process so as to leave a waveguide region in which the surface of the upper clad 8 is inclined under the influence of the core 6, and FIG. As shown in FIG. 2, W is used by reactive ion etching using CF4 + CHF3 gas.
The Six film 9 is etched. The end face of the waveguide formed by etching at this time is set within a range of about 8 μm or less to suppress loss from the core end to the Si platform side. Next, as shown in FIG. 2 (P), using the WSix film 9 after etching as a mask, an upper cladding layer 8 and a height adjusting cladding layer 5 are formed using C2H4 + C2F6 gas.
Is etched at 18.5 μm while leaving a thickness of 1 μm, and thereafter, as shown in FIG. 2 (Q), the WSix film 9 is removed by etching with SF 6 gas.

Next, as shown in FIG. 3 (R), a Cr / Au / Sn electrode 10 for dice bonding of a laser diode is vapor-deposited and patterned with reference to the end face of the waveguide. As shown in ()), the laser diode 11 is mounted. As described above, according to the manufacturing method of this embodiment, the upper cladding layer covering the core is removed after the upper cladding layer passes the end of the core pattern. The required film thickness is reduced, and the etching time is reduced. In addition, since the quartz layer is thin, the thickness of the mask material used for etching can be reduced, and the etching time of the mask material can be reduced.
Here, the end of the optical waveguide and the optical element are separated by the interposition of the upper cladding layer, but the upper cladding layer is approximately 8 μm or less from the core end as a guide. By exposing the end face by etching, optical connection with an optical fiber can be performed with a practically sufficiently low loss.

Next, a second embodiment of the present invention will be described with reference to FIGS.
The manufacturing process will be described with reference to FIG. 4 to 6
Is a process explanatory view showing a manufacturing method of an embodiment of the optical waveguide device of the present invention, FIG. 7 is a main part configuration diagram showing an embodiment of the optical waveguide device of the present invention, the optical waveguide device here, It has an optical connection configuration between an optical waveguide and an optical fiber. In the manufacture of the optical waveguide device of this embodiment, first, as shown in FIG. 4A, a V-groove for supporting an optical fiber on the Si substrate 21 by aligning the optical fiber with the waveguide is formed using the Si substrate 21. SiO2 film 2 as a mask material for performing
2 is formed to a thickness of 200 nm by thermal oxidation. Next, FIG.
As shown in (B), an organic resist pattern 23 for forming a V-groove is formed by a normal photolithography process, and thereafter, FIG.
As shown in (C), the organic resist pattern 23 and CF
Using 4 + O2 (5%) gas, the SiO2 film 22 is etched by a reactive ion etching apparatus. Next, as shown in FIG. 4D, a KOH aqueous solution (80%)
After immersing in 80 ° C. and leaving for 115 minutes to form a V-groove 25 having a depth of 133 μm, immersing in hot water and washing with water, as shown in FIG. .

Next, as shown in FIG. 5F, C2F6 gas is mixed with TEOS (tetraethoxysilane) + O2 gas over the entire surface of the Si substrate 1 by a plasma CVD method to have a refractive index of 1.4510 and a thickness of 1.410. A lower cladding layer 26 of SiO2 having a thickness of 25 .mu.m is formed.
The core layer 27 whose refractive index was reduced by 0.3% from the cladding layer by only (tetraethoxysilane) + O2 gas was 8 μm.
Next, as shown in FIG. 5 (G), a thickness of 1 μm
Is formed by an RF sputtering apparatus using an Ar gas and a Si target, and then, as shown in FIG. 5H, the α-Si film 28 is formed using a normal photolithography technique.
An organic resist pattern is formed thereon, and the α-Si film 28 is processed into a waveguide shape by reactive ion etching using HBr gas. At this time, the pattern of the α-Si film 28 is such that its end ends near the end of the V-groove 25, and the α-Si film 28 is also etched at the optical fiber connection end surface at the same time. . Organic resist is O
2 Remove ashing with plasma. Next, as shown in FIG. 5 (J), the core layer is vertically cut into a waveguide shape by a reactive ion etching method using C2F6 + C2H4 gas using the .alpha.-Si film 28 of the optical waveguide pattern as a mask. The core 27 is formed by patterning as follows, and then the α-Si 28 is removed with SF 6 gas in the same vacuum. Next, as shown in FIG.
m upper cladding layer 29 is formed by a plasma CVD method under the same conditions as the formation of the lower cladding layer 26, and then, as shown in FIG. 1 μm is formed by a sputtering method.

Next, as shown in FIG. 6 (M), a resist pattern is formed by a usual photolithography process so as to leave a necessary waveguide region, and the WSix film 30 is formed by reactive ion etching using CF4 + CHF3 gas. Is etched. At this time, a small 2
A WSix film 30 having a lens-shaped region 31 is formed so that a two-dimensional lens-shaped cladding region can be formed. Next, as shown in FIG.
Using 0 as a mask, the upper cladding layer 29 is removed by etching using C2H4 + C2F6 gas, and then the WSix film 30 is removed by etching with SF6 gas as shown in FIG. Thereafter, the optical fiber is inserted into the V-groove, and a UV curable resin having the same refractive index as that of the optical fiber core is applied to the bonding surface and bonded to complete. FIG. 7 shows a main configuration of an optical waveguide device before applying an ultraviolet curable resin. The optical waveguide device uses a substrate 21 on which a V-groove 25 having an inclined surface 25a at an end of the groove is formed. , Comprising a lower cladding layer 26, a core 27 and an upper cladding layer 29.
A type in which an optical waveguide formed on the substrate 21 extending in the longitudinal direction of the groove and the optical fiber 10 arranged in the V groove 25 of the substrate 21 are optically connected in the region of the V groove inclined surface 25a of the substrate 21. belongs to. In the optical waveguide device of this embodiment, a cladding region 29a of an upper cladding layer 29 is provided at the end of the core 27 of the optical waveguide in FIG. Since the upper clad layer 29 has a convex lens structure when viewed in plan, light from the optical waveguide is focused on the core 11 of the optical fiber 10. As described above, according to this embodiment, there is no need to perform a step such as cutting out the Si end face using a dicing saw, and therefore, the manufacturing is easy. In this embodiment, the distance between the optical waveguide and the optical fiber core is equal to the inclination of the V-groove of the Si substrate, but excessive loss is caused by the lens effect of the upper cladding region at the end of the optical waveguide. First, optical connection loss can be suppressed to a practically small value.

[0013]

As described above, in the manufacturing method according to the present invention relating to the optical waveguide device for optically connecting the optical waveguide and the optical element, when forming the core of the optical waveguide, the core end is connected to the platform. Since it is positioned near the end of the flat surface and only the clad layer is etched in etching on the platform, the required etching time can be shortened. Further, in the optical waveguide device for optically connecting the optical waveguide and the optical fiber, the two-dimensional lens-shaped cladding region is provided at the end of the optical waveguide, so that the manufacturing is simple and the optical connection loss is practically sufficient. There is an effect that can be reduced.

[Brief description of the drawings]

FIG. 1 is a process explanatory view showing a first embodiment of the present invention.

FIG. 2 is a process explanatory view showing the first embodiment of the present invention.

FIG. 3 is a process explanatory view showing the first embodiment of the present invention.

FIG. 4 is a process explanatory view showing a manufacturing method in an optical waveguide device according to a second embodiment of the present invention.

FIG. 5 is a process explanatory view showing a manufacturing method in an optical waveguide device according to a second embodiment of the present invention.

FIG. 6 shows a method for manufacturing an optical waveguide device according to a second embodiment of the present invention.

FIG. 7 is a main configuration diagram showing a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Si substrate 2 Si02 film 3 Platform 4 Lower cladding layer 5 High adjustment cladding layer 6 Core layer 7 α-Si layer 8 Upper cladding layer 9 WSix 10 Bonding Cr / Au / Sn10 11 Laser diode

Claims (2)

[Claims] 1. A substrate having a platform on which an optical element is mounted, a lower cladding layer laminated on a predetermined region of the substrate excluding the platform, and a high layer laminated on the lower cladding layer including the platform. A step of manufacturing a substrate laminate comprising: a cladding layer for adjusting the thickness; and, after forming a core layer on the substrate laminate, etching and patterning the core layer to form an edge portion of the platform. Forming a core having one end, and leaving at least a part of the upper cladding layer and at least a part of the height adjusting cladding layer on the platform except for a partial region near the end of the core. Vertically etching away, wherein an optical element is mounted on the platform, and light enters and exits the core part. A method of manufacturing an optical waveguide device, comprising manufacturing an optical waveguide device having a structure adapted to be performed via the upper cladding layer. 2. A substrate having a V-shaped groove having an inclined surface at an end of the groove, a lower clad layer, a core, and an upper clad layer, the V-shaped groove extending in a longitudinal direction of the V-shaped groove on the substrate. The formed optical waveguide, comprising an optical fiber fixed to the V-groove of the substrate, the end of the optical waveguide and the end of the optical fiber in the region of the inclined surface of the substrate facing each other In the optical waveguide device adapted to be optically connected, the end of the optical waveguide is provided with a cladding region of the upper cladding layer, which surrounds the end with a two-dimensional lens shape. Optical waveguide device.