JP2743847B2 - Optical fiber mounted optical waveguide circuit and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber-mounted optical waveguide circuit for high-precision, unadjustable coupling between an optical waveguide and an optical fiber required for optical communication, and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, as a method of connecting an optical waveguide and an optical fiber without adjusting the optical axis, there is a method using an optical fiber guide provided with a V-groove in Si (silicon).

In a circuit in which a quartz glass optical waveguide is formed on a Si substrate, for example, Japanese Patent Publication No. Sho 63-25644 discloses that a high efficiency connection between an optical waveguide and an optical fiber can be achieved. As a method of reducing the alignment error between the position where the groove is formed and the position where the optical waveguide is formed, a pattern for an optical fiber alignment guide at the same time as the optical waveguide circuit patterning on the silica glass based optical waveguide, and A ridge-type optical waveguide pattern is formed, a Si-based substrate is etched to an appropriate depth using a quartz-based optical waveguide layer pattern as a mask, and an optical circuit with a fiber guide as an optical fiber guide and a method of manufacturing the same are proposed. ing.

In this prior art, if the reduction of the waveguide pattern width due to the dry etching of the optical waveguide layer is accurately controlled, the displacement of the optical axis of the optical waveguide and the optical fiber in the in-plane direction of the substrate can be corrected by photolithography. Can be suppressed to about the drawing accuracy of the mask for use.

[0005]

As shown in FIG.
In the conventional optical circuit with a fiber guide and the method of manufacturing the same (referred to as "conventional example") disclosed in Japanese Patent Publication No. 63-25644, the optical fiber core 2f and the optical fiber guide 2 are used.
Patterns can be formed at the same time.

Further, in the above-mentioned conventional example, there is an advantage that the optical fiber guide 2 also serving as a mask for Si etching for adjusting the height of the optical fiber can be formed at the same time when the end face of the optical waveguide 3 is formed.

However, in the conventional example, the side surface of the optical waveguide core 3f is not embedded by the cladding of the low refractive index material, and has a structure in which it is in direct contact with air. In general, the refractive index difference of air with respect to the core of the optical waveguide is much larger than the refractive index difference of the core of the low refractive index material for cladding.

For this reason, when manufacturing a single-mode optical waveguide advantageous for the configuration of the optical waveguide functional device, in the conventional configuration in which the core is not completely buried with the low-refractive-index material cladding, the core has a low refractive index. The cross-sectional dimensions of the core must be much smaller than when embedded in the material cladding.

In this case, due to a mismatch (mismatch) in the mode field such as a difference in spot size and asymmetry of the beam mode profile, the core is completely buried with the low refractive index material clad. It becomes difficult to couple with a single mode optical fiber with high efficiency.

Further, when the side surface of the optical waveguide core comes into contact with air having a large refractive index difference, the guided light is easily affected by scattering due to the surface shape roughness of the side surface of the optical waveguide core, and the loss increases.

Furthermore, in the conventional example, only the side surface of the optical fiber guide 2 made of a silica-based optical waveguide layer formed by dry etching is provided in the substrate surface direction (horizontal direction) to support the optical fiber. In the direction perpendicular to the substrate surface (height direction), it is supported only by grooves formed on the Si substrate by anisotropic etching, that is, the Si (100) surface 1a.

However, in the conventional example, since the optical axis of the optical fiber is positioned by such support, there are various problems as described below.

When the etching is deep, the width of the pattern of the optical fiber guide made of a quartz-based material formed by dry etching is greatly reduced with respect to the original pattern width of the etching mask. Due to this, the width between the two optical fiber guides 2 sandwiching the optical fiber greatly increases with respect to the design value. For this reason, when the optical fiber guide is to be formed, it is necessary to design the optical fiber guide including compensation in which this spread is assumed in advance.

However, since there is an error in the actual etching, if the actual optical fiber guide width becomes wider than the design value in consideration of the compensation, the optical fiber is not fixedly supported in the in-plane direction of the substrate. , An optical axis shift occurs.

Conversely, if the actual width of the optical fiber guide is smaller than the design value in consideration of the compensation, there is a problem that the optical fiber cannot be sandwiched between the optical fiber guides.

Further, since the optical fiber is supported in contact with the Si (100) surface 1a formed by the Si etching, the adjustment of the optical axis position of the optical fiber in the direction perpendicular to the substrate requires the adjustment of the etching depth of Si. Must be done by

Therefore, the deviation from the set value of the Si etching depth directly becomes the positional deviation of the optical axis of the optical fiber.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a light-emitting device that couples an optical fiber to an optical waveguide in which a core is embedded by a cladding without adjustment and with high efficiency. An object of the present invention is to provide a fiber-mounted optical waveguide circuit and a method for manufacturing the same.

[0019]

In order to achieve the above object, the present invention provides an optical fiber-mounted optical waveguide circuit in which an optical waveguide and an Si V-groove for mounting an optical fiber are formed on a Si substrate. Rights of the manufacturing process, the (a) Si
A step of simultaneously patterning the V groove forming mask pattern of the optical waveguide core pattern and Si after depositing the optical waveguide core layer on a surface substrate, etching the to (a-1) the optical waveguide core layer (B) removing the mask of only the portion of the optical waveguide core pattern while leaving the mask of the portion of the V-groove forming mask pattern; and (c) refracting the upper surface and side surfaces of the optical waveguide core from the optical waveguide core. (E) a step of simultaneously forming an optical waveguide end face by etching and forming a block of an optical waveguide layer serving as a mask for forming a Si V-groove, and (e)
And an anisotropic etching of Si using the block as a mask.

In the present invention, in order to increase the precision of forming the V-groove for supporting the optical fiber, preferably, a Si-substrate is provided between the block composed of the optical waveguide layer serving as a mask for forming the V-groove of Si and the Si substrate. A layer made of a material that is difficult to be etched by the V-groove forming etchant and formed in the form of a Si V-groove mask pattern is inserted, and this layer is used as a mask when forming the Si V-groove. It may be.

Further, in the present invention, preferably, the layer inserted between the block and the Si substrate is made of WSi.

Further, in the present invention, preferably,
After the step (a), a step of etching up to the optical waveguide core layer is included.

In the method of manufacturing an optical fiber-mounted optical waveguide circuit according to the present invention, an optical fiber-mounted optical waveguide having an Si waveguide and a V-shaped groove for mounting the optical fiber on a Si substrate. In the method of manufacturing a waveguide circuit, (a) a step of simultaneously patterning an optical waveguide core pattern and a mask pattern for forming a V-groove of Si after deposition of an optical waveguide core layer; and (b) a step of forming the mask pattern for forming the V-groove. Removing the mask of only the portion of the optical waveguide core pattern while leaving the partial mask; and (c) covering the region from the V-groove forming portion of the Si substrate to the end surface of the optical waveguide core with a cover mask. (D) forming an upper cladding layer on the cover mask and the optical waveguide region and embedding the optical waveguide core in the upper cladding layer; and (e) removing the cover mask and removing the Si. Removing the upper cladding layer located above the groove forming portion, and (f) forming an optical waveguide end face forming dry etching mask so as to cover the upper cladding layer above and on the side of the optical waveguide core. (G) simultaneously forming the optical waveguide end face and forming the Si V-groove forming mask; and (h) forming a V-groove in the Si substrate by anisotropic etching.
May be included.

In the present invention, preferably, the Si
A cutting groove deeper than the V-groove is provided on the substrate to shape an end face of the optical waveguide core.

According to another aspect of the present invention, an optical waveguide including an optical waveguide core is provided on a Si substrate, and a Si V-groove for mounting an optical fiber on the Si substrate is provided. An optical fiber-mounted optical waveguide circuit, wherein a pattern of a Si V-groove is formed using the same mask, wherein the optical fiber is mounted on the side surface (111) of the Si V-groove at the time of mounting the optical fiber. The present invention provides an optical fiber-mounted optical waveguide circuit characterized in that it is supported in contact with the optical fiber.

In the optical fiber mounted optical waveguide circuit according to the present invention, preferably, the optical waveguide core is covered with a clad having a lower refractive index than the core.

Further, in the optical fiber package type optical waveguide circuit according to the present invention, a cut groove deeper than the V groove is provided in the Si substrate.

[0028]

According to the present invention, the core pattern of the optical waveguide and the pattern of the mask for forming the Si V-groove for the optical fiber are simultaneously formed using the same light exposure mask in photolithography. An anisotropic etching mask for forming a Si V-groove is also formed at the same time.

As a result, as in the above-described conventional example, the optical waveguide core pattern and the V
There is no need to align the pattern of the groove forming mask.

Therefore, according to the present invention, the Si V-groove (1
11) The positional accuracy of the optical axes of the optical fiber and the optical waveguide core supported by the surface in the in-plane direction of the substrate can be remarkably improved to the same level as the drawing accuracy of the mask pattern in photolithography.

In addition, V of Si composed of a quartz-based material
When the groove forming mask is formed by dry etching of the optical waveguide layer, the width between the V-groove forming masks is larger than a designed value, and therefore it is necessary to design the V-groove including compensation in advance. However, according to the present invention, since the optical fiber is supported by the (111) plane of the Si V-groove, the width between the V-groove forming masks is reduced due to an error in the actual etching with respect to the compensation design. Even if it spreads, the optical fiber is fixed and supported in the in-plane direction of the substrate.

Further, the position of the optical axis of the optical fiber in the direction perpendicular to the substrate varies due to an error with respect to the design value of the etching depth of Si, but the etching rate of the (111) plane is much smaller than that of the (100) plane. Therefore, in the present invention,
Since the optical fiber is supported by being in contact with the (111) plane, the positioning of the optical fiber optical axis in the direction perpendicular to the substrate is less likely to be affected by errors in the etching depth of Si.

By the above operation, the present invention improves the positional accuracy of the optical axes of the optical waveguide and the optical fiber both in the in-plane direction and in the direction perpendicular to the substrate, as compared with the conventional method.

According to the present invention, after forming the core layer, which is a step before depositing the upper clad layer, the optical waveguide core and the mask pattern for forming the V-groove of Si are simultaneously formed, and then only the optical waveguide core layer is formed. The optical waveguide core can be completely embedded with a low refractive index material cladding for etching and further depositing a cladding layer.

Thus, according to the present invention, the upper and lower surfaces and the side surfaces of the optical waveguide core are in contact with not the air but the clad having a slightly lower refractive index than the core. Therefore, a single mode optical waveguide having a spot size and a beam mode profile close to that of a single mode optical fiber can be easily formed.

Therefore, in the present invention, the optical waveguide and the single mode optical fiber can be coupled with high efficiency. Further, scattering loss due to the surface shape roughness of the core side surface is also smaller than when the core side surface is in contact with air.

[0037]

Embodiments of the present invention will be described below with reference to the drawings.

[0038]

Embodiment 1 FIG. 1 is a perspective view showing a structure of an optical fiber mounted optical waveguide circuit according to an embodiment of the present invention before mounting the optical fiber.

Referring to FIG. 1, by simultaneously patterning the optical waveguide core pattern and the Si V-groove forming mask pattern, the two V-groove portion dry etching masks 4a of FIG. 1 are viewed from the substrate direction. Are formed so as to be aligned with the center line of the optical waveguide core pattern.

The Si V-groove forming mask 7 is formed by dry etching using the V-groove dry etching mask 4a as a mask and the optical waveguide end face 13a using the optical waveguide end face dry etching mask 4b as a mask. Formed at the same time.

The Si V-groove forming mask 7 is
b, a lower cladding layer 3d and a V-groove dry etching mask 4a.

In the figure, reference numeral 3g denotes a cladding layer, which comprises a lower cladding layer 3d and an upper cladding layer 3e.

The sectional size of the optical waveguide core 3f is, for example, 5
× 5 μm and a refractive index slightly lower than the core (the relative refractive index difference of the optical waveguide core with respect to the cladding is, for example, 0.5
%) Is in contact with the cladding layer 3g.

In this embodiment, a single-mode optical waveguide having a spot size and a beam mode profile close to those of a single-mode optical fiber can be easily formed by such a configuration.

Therefore, the optical waveguide and the single-mode optical fiber can be more efficiently coupled as compared with the case where the air and the side surface of the core are in direct contact. The optical waveguide core 3f
The scattering loss due to the surface shape roughness of the side surface of the optical waveguide is also smaller than when the optical waveguide core side surface is in contact with air.

FIG. 2 shows a structure in which the optical fiber 6 is mounted in the Si V-groove 5 in the embodiment of the optical fiber mounted optical waveguide circuit. That is, FIG. 2 corresponds to a cross-sectional view of the optical fiber-mounted optical waveguide circuit of FIG. 1 in which the optical fiber is mounted in the V-groove 5 of Si and cut perpendicular to the optical axis direction of the optical fiber. It is sectional drawing of the XX 'line seen from the line A direction.

Referring to FIG. 2, a block made of an optical waveguide layer of silica glass etched and formed by a V-groove dry etching mask 4a is not used as an optical fiber fixing guide but for an optical fiber non-adjustment fixed mounting. Is used as a mask for forming the Si V-groove 5 by etching.

As shown in FIG. 2, the optical fiber 6 is supported by the V-groove Si (111) surface 1b.

FIGS. 3 to 9 are views showing the steps of an embodiment of a method of manufacturing the optical fiber-mounted optical waveguide circuit of the embodiment of FIG.

Referring to FIG. 3, optical waveguide core pattern 9
And the V-groove forming mask pattern 8 of Si and the mask (optical waveguide core forming dry etching mask 4c and V-groove dry etching mask 4a) patterned into the respective shapes of the V-groove forming mask pattern 8 are the core layer (also referred to as the “optical waveguide core layer”) Say) 3b
Are formed all at once.

Therefore, the axis of symmetry of the two V-groove forming mask patterns 8 of Si and the center line of the optical waveguide core pattern 9 completely overlap.

More specifically, referring to FIG. 3, first, (1
00) A lower cladding layer 3d made of, for example, quartz glass containing P and B (having a thickness of, for example, 10
μm) is formed by a CVD method, a flame deposition method, or the like (Step 2), and a core layer 3b (for example, having a thickness of 5 μm) made of quartz glass containing P, B, and Ge is formed on the lower cladding layer 3d.
μm) is formed by a CVD method, a flame deposition method, or the like (Step 3).

Next, a layer of, for example, Cr or the like is formed on the core layer 3b by sputtering or vapor deposition (step 4).

Thereafter, a photoresist is applied (step 5), and a dry etching mask 4 for forming an optical waveguide core is formed using a method such as laser drawing or photolithography.
The c and V-groove dry etching masks 4a are collectively formed (step 6).

In this case, the mask formed in the step 6 includes, for example, a Cr layer and a photoresist layer thereover. This mask can be formed by patterning a photoresist into a desired shape by a method such as photolithography, and then patterning a Cr layer under the photoresist with a Cr etching solution using the pattern. .

Referring to FIG. 4, core layer 3 of the optical waveguide is formed by reactive ion dry etching or the like using a CF-based gas or the like.
b is etched (step 7).

As a result, the optical waveguide core 3f is formed under the dry etching mask 4c for forming the optical waveguide core, and the core layer 3b under the V-groove dry etching mask 4a is also used for forming the Si V-groove. Etching is performed simultaneously in the shape of the mask pattern 8.

Next, among the masks used for the dry etching in the step 7, the V-groove dry etching mask 4
The mask 4c for dry etching for forming the optical waveguide core is removed while leaving a as it is (Step 8).

Thereafter, the upper cladding layer 3e (for example, 10 μm) made of, for example, quartz glass containing P and B is subjected to CVD.
A film is formed by a method or a flame deposition method (Step 9).

As a result, as shown in FIG. 5, the optical waveguide core 3f is embedded with a cladding material having a slightly lower refractive index than the core.

FIGS. 5 to 7 are diagrams for explaining this state. 5 is a perspective view, FIG. 6 is a view showing a cross section as viewed from the direction of arrow A in FIG. 5, and FIG. 7 is a view showing a cross section as viewed from the direction of arrow B in FIG.

Next, referring to FIG. 8, after step 9, the upper clad layer 3i in contact with the upper part of the optical waveguide core 3f and the upper clad layer 3j on the side of the optical waveguide core 3f are covered. An optical waveguide end face forming dry etching mask 4b is provided at a position as shown in FIG.

The same method as in the above-described steps 4, 5, and 6 is used for forming the dry etching mask 4b for forming the end face of the optical waveguide.

The position where the mask is formed does not need to be very precise. That is, it is sufficient that the accuracy is such that the boundary of the mask substantially overlaps the position of the end face of the target optical waveguide core. However, since the end face of the optical waveguide core 3f must be exposed outside the upper clad layer 3e by the etching in the next step 11, the boundary line of the mask may be slightly shifted to the optical waveguide core 3f side. .

Next, the upper clad layer 3e and the lower clad layer 3d which are not covered with the optical waveguide end face forming dry etching mask 4b provided in the previous step 10 are removed by reactive ion dry etching or the like (step). 11).

At this time, the core layer 3b and the lower clad layer 3d under the V-groove dry etching mask 4a remain without being removed.

As a result, as shown in FIG. 9, at the same time as forming the end face 13a of the optical waveguide, the two Si V-groove forming masks 7 are positioned with high precision with respect to the position of the optical waveguide core 3f. (Ie, a state in which the central axis of the optical waveguide core 3f is included in the mirrored surfaces of the two V-groove forming masks 7 of Si).

At this point, since the Si (100) surface 1a at the location where the V-groove is to be etched is exposed, the KOH is formed using the Si V-groove forming mask 7 described above.
Anisotropic etching of the Si substrate 1 is performed using an etching solution such as (Step 12).

As a result, a Si V-groove 5 is formed in which the position of the optical axis of the optical waveguide core 3f coincides with the position of the optical axis in the in-plane direction of the substrate, and an optical fiber-mounted optical waveguide circuit as shown in FIG. 1 is produced.

In the above embodiment, the mask 4c for dry etching for forming the optical waveguide core on the optical waveguide core 3f is removed in step 8, but this removal may be performed as follows. For example, only the upper portion of the V-groove dry etching mask 4a is covered with a thick-film resist or the like.
In the case where a layer of Cr is used as an example,
What is necessary is just to remove the Cr layer by an etchant.

If all the masks used for the reactive ion dry etching in the step 7 are removed, the V
When the reactive ion dry etching is performed again in step 11, even the quartz glass-based optical waveguide layer (core layer 3b, lower clad layer 3d) at a position to be processed and formed to become the groove forming mask 7 is formed. Will be etched away. Therefore, in the mask removal in step 8, V
It is indispensable that the trench dry etching mask 4a is always left without being removed.

The optical fiber mounted optical waveguide circuit thus formed supports the optical fiber on the Si (111) surface 1b of the Si V-groove 5, as shown in FIG. As a result, in both the in-plane direction and the substrate vertical direction of the Si substrate 1, the optical fiber can be fixedly mounted on the optical waveguide core 3f with high precision without adjustment, and the optical waveguide core 3f
Is embedded in a clad 3g layer of a material having a slightly lower refractive index than the core.

[0073]

Embodiment 2 FIGS. 10 and 11 are views showing steps of another embodiment of the manufacturing method according to the present invention, which is partially different from the first embodiment. FIG. 12 is a perspective view showing a configuration of an optical fiber-mounted optical waveguide circuit in a manufacturing process according to the present embodiment.

In this embodiment, after the step 8 of the first embodiment, as shown in FIG. 10A, a portion from the Si V-groove forming portion 14 to the end face of the optical waveguide core 3f is formed. Is thickly covered with a cover mask 10 (step A).

Referring to FIG. 10B, an upper clad layer 3e is formed next, and the optical waveguide core 3f is buried with a clad material having a slightly lower refractive index as shown in FIG. B).

Referring to FIG. 10C, the upper clad layer 3e located above the Si V-groove forming portion is removed by a lift-off effect by removing the cover mask 10 (step C). .

Further, the upper clad layer 3i in contact with the upper part of the optical waveguide core 3f and the upper clad layer 3j on the side of the optical waveguide core 3f are covered by FIGS.
As shown in (1), a dry etching mask 4b for forming an end face of an optical waveguide is provided (Step 10 ').

Then, as shown in FIG. 11E, the formation of the end face of the optical waveguide and the formation of the Si V-groove forming mask 7 are simultaneously performed by reactive ion dry etching or the like (step).
11 ') Finally, a V-groove is formed by anisotropic etching (step 12').

[0079]

[Embodiment 3] In the case where an optical waveguide is made of quartz glass, at the time of forming the V-groove in the above-described step 12,
The end face 13a of the optical waveguide is also slightly etched by an etching solution such as KOH.

For this reason, an undercut may occur under the dry etching mask 4b for forming the end face of the optical waveguide, and the end face 13a of the optical waveguide may not be flat.

Further, of the Si (111) surface appearing by the anisotropic etching, the end of the optical fiber hits the (111) surface whose edge 13a is the edge of the optical waveguide, so that the end of the optical fiber is connected to the optical waveguide portion. Cannot be completely abutted against the end face 13a.

Such a problem, as shown in FIG.
By providing a cutting groove 15 deeper than the V groove with a dicing saw or the like (step 13), the problem can be solved by shaping the end face of the optical waveguide core 3f.

Referring to FIG. 13, by providing a cutting groove 15 deeper than the V groove shown by the broken line, the cover mask in step A in the second embodiment and the first and second steps 10 and Precision is not required for forming the optical waveguide end face forming dry etching mask 4b in 10 '.

[0084]

Fourth Embodiment As another problem, the quartz glass optical waveguide layer is eroded by an etching solution such as KOH during the etching of Si, so that the Si V-groove forming mask 7 recedes in FIG.

For this reason, the formation position of the Si V-groove 5 (FIG. 1)
), And this error appears as an increase in the width of the V-groove.

Therefore, as a method of reducing the above error,
The V-groove dry etching mask 4a layer, the core layer 3b, the lower cladding layer 3
Instead of the structure consisting of only d, as shown in FIG.
The thin film layer 11 made of tungsten silicide WSi or the like
A structure inserted between the i-substrate 1 and the lower clad layer 3d of the optical waveguide can also be used.

The thin film layer 11 made of WSi or the like is hardly etched by an anisotropic etching solution of Si such as KOH.
It becomes a direct mask for forming a Si V-groove.

The thin film layer 11 of WSi or the like is formed by, for example, forming a film by a sputtering method or the like before depositing the optical waveguide clad layer.

As described above, the thin film layer 11 such as WSi
In the case of a structure inserted between the i substrate 1 and the lower cladding layer 3d, the V groove 5 is formed in the Si substrate 1 by anisotropic etching.
Before the formation of the V-groove, the thin film layer 11 of WSi or the like is patterned in the form of a V-groove formation mask so as to serve as a direct mask for V-groove formation etching. Must be exposed.

As for the patterning of the thin film layer 11 of WSi or the like, one method is as follows.
Subsequent to the reactive ion dry etching of the lower cladding layer 3d, the thin film layer 11 of WSi or the like is etched and patterned using an appropriate etchant (step E). For example, there is a method of performing dry etching using Ar ions or the like. In this case, a manufacturing method basically similar to that described with reference to FIGS. 3 to 9 is used.

FIGS. 14 to 16 show a thin film layer 11 of WSi or the like.
Is inserted between the Si substrate 1 and the lower clad layer 3d in a structure different from that of the first embodiment.
It is process drawing of the manufacturing method which forms the mask for V groove formation of i.

That is, at the time of the reactive ion dry etching of the core layer 3b in the step 7 of the first embodiment, not only the core layer 3b but also the lower cladding layer 3d below the core layer 3b.
Is also etched (step H) as shown in FIG.
Subsequently, as shown in FIG. 14I, a thin film layer of WSi or the like is formed by using an appropriate etchant (for example, Ar ions).
The patterned etching of Step 11 is performed (Step I).

In the latter method, after this etching,
The optical waveguide core forming dry etching mask 4c is removed to obtain the one as shown in FIG. 15 (j) (step J).

Next, as shown in FIG. 15 (k), the portion from the Si V-groove forming portion 14 to the end face of the optical waveguide core 3f is thickly covered with the cover mask 10 (step K), and the upper clad layer is further formed. 3e is formed (Step L).

As a result, the optical waveguide core 3f is buried by the lower cladding layer 3d and the upper cladding layer 3e having a slightly lower refractive index than the core, as shown in FIG.

Thereafter, as shown in FIG. 16 (m), by removing the cover mask 10, the upper clad layer 3e above the V-groove formation portion of Si is lifted off (step M).

Then, as shown in FIG. 16 (n), the upper cladding layer 3e above the optical waveguide core 3f is covered with the optical waveguide end face forming dry etching mask 4b (step N), and reactive ion dry etching or the like is performed. As a result, the formation of the end face of the optical waveguide and the formation of the mask for Si anisotropic etching are performed simultaneously (step O, see FIG. 15 (o)).

When the V-groove is formed by the subsequent anisotropic etching of Si, the end face of the optical waveguide is also slightly etched.

In this regard, the same processing as described in the embodiment with respect to the structure in which the thin film layer of WSi or the like is not inserted between the Si substrate and the lower clad layer may be performed.

That is, as shown in FIG. 13, the end face of the optical waveguide core 3f may be shaped by providing a cutting groove 15 deeper than the V groove with a dicing saw or the like (step 1).
3). In this case, precision is not required for the mask formation in Step 10, Step K, and Step N.

As a method partially different from the above-mentioned method, after the cover mask 10 is removed in the step M, the formation of the optical waveguide end face forming dry etching mask 4b in the step N and the reactivity in the step O are performed. The silicon V-groove formation etching is performed without going through the ion dry etching process, and subsequently, the end face of the optical waveguide is shaped by a dicing saw or the like.

This has the advantage of simplifying the process, in that reactive ion dry etching only needs to be performed once when forming the core.

As an etchant used in the anisotropic etching for forming the Si V-groove in the step 12, in addition to KOH, NaOH, CsOH, NH ₃ OH, N ₂ H ₄ , ethylenediamine, hydrazine and the like are used. Can be

Although the present invention has been described with reference to the above embodiments, the present invention is not limited to the above embodiments but includes various embodiments according to the principle of the present invention.

[0105]

As described above, according to the present invention (claim 1), in the non-adjustment mounting of the optical fiber on the quartz light glass optical waveguide circuit, the in-plane direction of the substrate and the substrate in comparison with the conventional method are reduced. The positional accuracy of the optical axis of the optical waveguide and the optical fiber in the vertical direction can be improved. Therefore, according to the present invention, there is an effect that the loss can be reduced in the unadjusted coupling between the optical waveguide and the optical fiber.

According to the present invention, after forming the core layer, which is a step before depositing the upper clad layer, the optical waveguide core and the mask pattern for forming the V-groove of Si are simultaneously formed, and then only the optical waveguide core layer is formed. Since the etching process is performed and the clad layer is further deposited, the optical waveguide core can be completely embedded by the low refractive index material clad. As a result, the optical waveguide core comes into contact with the upper and lower surfaces and the side surfaces, not with air, but with the clad having a slightly lower refractive index than the core.

Therefore, according to the present invention, a single-mode optical waveguide having a spot size and a beam mode profile close to those of a single-mode optical fiber can be easily formed. As a result, according to the present invention, a single-mode optical fiber can be efficiently coupled to an optical waveguide. Further, according to the present invention, the scattering loss due to the surface shape roughness of the core side surface is also smaller than when the core side surface is in contact with air.

Further, according to the present invention (claim 2), Si
The groove width of the Si V-groove is formed by inserting a thin film layer made of a material that is hardly etched by the Si V-groove forming etchant between the block made of the optical waveguide layer serving as the V-groove forming mask and the Si substrate. Is suppressed, and the formation accuracy of the optical fiber supporting V-groove is increased.

Further, according to the present invention (claim 5),
The same effect as described above can be achieved even when the substrate is manufactured so as to cover the region from the V-groove forming portion of the substrate to the end face of the optical waveguide core with a cover mask.

According to the present invention (claim 6), V
With the configuration in which the cut groove is provided deeper than the groove, the accuracy required for forming, for example, the mask for dry etching for forming the cover mask and the end face of the optical waveguide is relaxed.

According to the optical fiber mounted optical waveguide circuit of the present invention (claim 7), the direction of the optical axis of each of the optical fiber and the optical waveguide core supported by the Si V-groove (111) surface in the substrate plane. Can be significantly improved to the same level as the drawing accuracy of a mask pattern in photolithography, and the loss can be reduced in the unadjusted coupling between the optical waveguide and the optical fiber.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a configuration of an optical fiber mounted optical waveguide circuit according to an embodiment of the present invention before the optical fiber is mounted.

FIG. 2 is a diagram showing a state of mounting an optical fiber in a V-groove of Si in the embodiment of the optical fiber-mounted optical waveguide circuit of FIG. 1; It corresponds to a sectional view.

FIG. 3 is a diagram sequentially illustrating the steps of an embodiment of the method for manufacturing an optical fiber-mounted optical waveguide circuit of the present invention.

FIG. 4 is a diagram sequentially illustrating the steps of an embodiment of the method for manufacturing an optical fiber-mounted optical waveguide circuit of the present invention.

FIG. 5 is a diagram sequentially illustrating the steps of an embodiment of the method for manufacturing an optical fiber-mounted optical waveguide circuit of the present invention.

FIG. 6 is a view showing a cross section viewed from the direction of arrow A in FIG. 5;

FIG. 7 is a diagram showing a cross section as viewed from the direction of arrow B in FIG.

FIG. 8 is a diagram sequentially illustrating the steps of an embodiment of the method for manufacturing an optical fiber-mounted optical waveguide circuit of the present invention.

FIG. 9 is a diagram sequentially illustrating the steps of one embodiment of the method for manufacturing an optical fiber-mounted optical waveguide circuit of the present invention.

FIG. 10 is a diagram sequentially illustrating the steps of a second embodiment of the method for manufacturing an optical fiber-mounted optical waveguide circuit according to the present invention.

11 is a diagram sequentially illustrating the steps of a second embodiment of the method for manufacturing an optical fiber-mounted optical waveguide circuit of the present invention (FIG. 1).
0 continuation).

FIG. 12 is a perspective view showing a configuration of an optical fiber-mounted optical waveguide circuit according to a second embodiment of the present invention.

FIG. 13 is a view for explaining cut grooves provided near an end face according to a third embodiment of the optical fiber mounted optical waveguide circuit of the present invention.

FIG. 14 is a diagram sequentially illustrating the steps of a fourth embodiment of the method of manufacturing an optical fiber-mounted optical waveguide circuit according to the present invention.

FIG. 15 is a diagram sequentially illustrating the steps of a fourth embodiment of the method of manufacturing an optical fiber-mounted optical waveguide circuit according to the present invention.

FIG. 16 is a diagram sequentially illustrating the steps of a fourth embodiment of the method of manufacturing an optical fiber-mounted optical waveguide circuit according to the present invention.

FIG. 17 is a perspective view showing a configuration of a conventional optical circuit with a fiber guide.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Si substrate 1a Si (100) surface 1b Si (111) surface 2 Optical fiber guide 3 Optical waveguide 3a Cladding layer 3b Core layer 3c Buffer layer 3d Lower cladding layer 3e Upper cladding layer 3f Optical waveguide core 3g Cladding layer 3i Optical waveguide core Upper clad layer 3j upper clad layer on the side of optical waveguide core 4a V-groove dry etching mask 4b optical waveguide end face formation dry etching mask 4c optical waveguide core formation dry etching mask 5Si V-groove 5a Si V-groove bottom 6 Optical fiber 7 Si V-groove forming mask 8 Si V-groove forming mask pattern 9 Optical waveguide core pattern 10 Cover mask 11 Thin film of WSi or the like which is hardly etched by Si V-groove forming etchant 12 V-groove for optical fiber 13 Optical waveguide 13a End face of optical waveguide 14 Si V-groove forming part 15 Cutting groove

Claims (9)

(57) [Claims] 1. A method of manufacturing an optical fiber-mounted optical waveguide circuit in which a Si V-groove for mounting an optical waveguide and an optical fiber on a Si substrate is provided. a step of simultaneously patterning the optical waveguide core pattern and Si V groove forming mask pattern <br/> after depositing a waveguide core layer, and etching the to (a-1) the optical waveguide core layer (B) removing the mask of only the portion of the optical waveguide core pattern while leaving the mask of the portion of the V-groove forming mask pattern; and (c) refracting the upper surface and side surfaces of the optical waveguide core from the optical waveguide core. A step of embedding with a material having a low efficiency, and (d) forming an end face of the optical waveguide by etching and forming a V of Si.
An optical fiber, comprising: simultaneously forming a block made of an optical waveguide layer serving as a mask for forming a groove; and (e) performing anisotropic etching of Si using the block as a mask. A method for manufacturing a mounted optical waveguide circuit. 2. A Si V-groove mask between a block made of an optical waveguide layer serving as a Si V-groove formation mask and the Si substrate, made of a material which is difficult to be etched by a Si V-groove formation etchant. 2. The method according to claim 1, wherein a layer formed in the form of a pattern is inserted, and the layer is used as a mask when forming a V-groove of Si. 3. The method of manufacturing an optical fiber-mounted optical waveguide circuit according to claim 2, wherein a layer inserted between said block and said Si substrate is made of WSi. 4. A method of manufacturing an optical fiber-mounted optical waveguide circuit in which a Si V-groove for mounting an optical waveguide and an optical fiber on a Si substrate is provided. a step of simultaneously patterning the optical waveguide core pattern and Si V groove forming mask pattern <br/> after depositing a waveguide core layer, and etching the to (a-1) the optical waveguide core layer (B) removing the mask of only the portion of the optical waveguide core pattern while leaving the mask of the portion of the V-groove forming mask pattern; and (c) the end face of the optical waveguide core from the V-groove forming portion of the Si substrate. And (d) forming an upper cladding layer on the cover mask and the optical waveguide region and embedding the optical waveguide core with the upper cladding layer, (e) Remove the cover mask Removing the upper cladding layer located above the V-groove forming portion of the Si; and (f) forming an optical waveguide end face dry so as to cover the upper cladding layer above and on the side of the optical waveguide core. Forming a mask for etching; (g) simultaneously forming an end face of the optical waveguide and forming a mask for forming a V-groove of Si; and (h) forming a V-groove in the Si substrate by anisotropic etching. A method for manufacturing an optical fiber-mounted optical waveguide circuit, comprising: 5. A cutting groove deeper than said V groove in said Si substrate.
And shaping the end face of the optical waveguide core.
The optical fiber mounting type according to any one of claims 1 to 4.
A method for manufacturing an optical waveguide circuit. 6. An optical waveguide including an optical waveguide core on a Si substrate, a Si V-groove for mounting an optical fiber on the Si planar substrate, wherein the optical waveguide core and the Si V-groove are provided. An optical fiber-mounted optical waveguide circuit in which a pattern is formed using the same mask, wherein the optical fiber is in contact with and supported by a side surface (111) of the V groove of the Si when the optical fiber is mounted. An optical waveguide circuit mounted with an optical fiber. 7. An optical waveguide layer serving as a mask for forming a Si V-groove.
Between the block made of Si and the Si substrate .
From materials that are difficult to etch with V-groove forming etchant
And formed in the shape of a Si V-groove mask pattern
7. The method according to claim 6, wherein the layers are sandwiched.
Optical fiber mounted optical waveguide circuit. 8. The optical waveguide core according to claim 1, wherein said optical waveguide core is covered with a clad having a lower refractive index than said core.
7. An optical fiber-mounted optical waveguide circuit according to item 6 . 9. An optical fiber-mounted optical waveguide circuit according to claim 7, wherein a cut groove deeper than said V groove is provided in said Si substrate.