JP2001015814A - Substrate for mounting optical component, manufacture therefor and optical module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a substrate for mounting an optical component of a structure, wherein the substrate can favorably be utilized to a even though an electrical signal for driving an optical semiconductor element is the high-frequency signal and moreover, the optical semiconductor element can be provided on the substrate with high accuracy and at the same time, the substrate is very excellent in performance and reliability, the manufacturing method of the substrate and an optical module. SOLUTION: This substrate is a substrate S for mounting an optical component, wherein a V-shaped groove 6 to be made to provide with an optical waveguide body is formed in a substrate 1 and markers 10 for mounting positioned to the groove 6 and conductors for driving an optical semiconductor element 13 which is made to provide on the substrate S on the basis of the markers 10, are formed on the substrate 1. With the conductors 7 and 8 provided on both of a first insulating film 2 formed on the substrate 1 and a second insulating film 4 formed thicker than the film 2 on the substrate 1, the markers 10 are formed on the film 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical component mounting substrate suitably used for optical transmission and optical communication, a method for manufacturing the same, and an optical module.

[0002]

2. Description of the Related Art Conventionally, a marker for mounting (positioning) an optical semiconductor element manufactured on a substrate is sometimes manufactured simultaneously with a V-groove for mounting an optical fiber. For example, FIG.
As shown in (a) and (b), a V-groove marker 52 formed on a substrate 51 by anisotropic etching is a photolithographic pattern using the same mask as a V-groove 53 for mounting an optical fiber. Is formed, the V-groove marker 52
The relative positional accuracy between the optical fiber and the V-groove 53 for mounting the optical fiber is determined by the accuracy of the photomask, and the positional accuracy hardly shifts.

In some cases, the above-mentioned marker is produced simultaneously with an electrode for mounting an optical semiconductor element. For example, FIG.
As shown in (a) and (b), the marker 54 formed of the same electrode material as the electrode 58 for mounting the optical semiconductor element is used.
Since the pattern is formed by directly reflecting the pattern for photolithography, it is easy to form a complicated shape in order to improve the mounting accuracy of the optical semiconductor element.

Further, as shown in FIGS. 8A and 8B, it is also known that an opening-shaped marker 55 is formed by etching a part of an insulating film 57 formed on a main surface of a substrate 51. Have been.

Further, as shown in FIGS. 9A and 9B, a pattern for forming a V-groove 53 for mounting an optical fiber, an electrode 58 for mounting an optical semiconductor element and a driving electrode for an optical semiconductor element. It is also known to form a so-called self-aligned marker that simultaneously creates a pattern for forming the marker 59 and a pattern for forming the marker 56 (for example, see Japanese Patent Application Laid-Open No. 10-170773).

[0006]

SUMMARY OF THE INVENTION As shown in FIG.
In the case of the groove marker, the optical fiber mounting V-groove and the V-groove marker which are finally formed are formed with the same mask in the photolithography process, so that their relative positions do not shift.

However, since the shape of the V-groove marker is generally produced by anisotropic etching,
As shown in FIGS. 10 (a) and 10 (b), even if the mask shape in the plane is circular, the plane is selectively etched by a specific square as shown in FIGS. 10 (c) and 10 (d). The shape is etched, and the shape is limited. It is also conceivable to form a mounting marker for an optical semiconductor element by combining a plurality of V-groove markers in order to increase mounting accuracy. However, when a plurality of mounting markers are combined, the entire mounting marker section becomes large. Becomes for that reason,
In order to increase the mounting accuracy when mounting the optical semiconductor element, it is difficult to enlarge and observe the entire mounting marker.

Further, in the case of the electrode marker and the insulating film marker shown in FIGS. 7 and 8, it is necessary to consider the shape of the marker so as to improve the mounting accuracy, and it is necessary to make the entire mounting marker larger. Therefore, the mounting marker can be enlarged and observed when the optical semiconductor element is mounted.

However, as shown in FIGS. 11 (a) (corresponding to FIG. 7) and (b) (corresponding to FIG. 8), the mounting markers 54 and 55 of the optical semiconductor element are provided with V-grooves for mounting optical fibers. Since the mask is manufactured using a different mask from that of the mask 53, the relative positional accuracy is about the same as the alignment accuracy of the mask alignment device (1-2.
μm).

Furthermore, in the case of the self-aligned marker shown in FIG. 9, since the self-aligned marker is manufactured using the same mask as the V-groove pattern for mounting the optical fiber, a small and complicated mounting marker pattern for the optical semiconductor element can be manufactured with high positional accuracy. Can be.

[0011] However, with the development of optical communication, there is a demand for a higher frequency of an electric signal for driving an optical semiconductor element, but it has been difficult to cope with the above technology. In other words, in order to increase the frequency of the electrical signal for driving the optical semiconductor element, even a substrate for mounting an optical semiconductor having a thick insulating film on a part of the substrate can have irregularities on the substrate, thereby forming an optical fiber. The V-groove pattern and the small and complicated mounting marker pattern could not be produced with high accuracy.

Therefore, the present invention can suitably cope with a high-frequency electric signal for driving an optical semiconductor element.
Moreover, it is an object of the present invention to provide an optical component mounting substrate, a method of manufacturing the same, and an optical module, which are capable of disposing optical semiconductor elements with high precision and which are extremely excellent in performance and reliability.

[0013]

In order to achieve the above object, an optical component mounting board according to the present invention has a V-shaped groove on which an optical waveguide is provided, and a V-shaped groove positioned on the V-shaped groove. A mounting marker and a driving conductor for disposing an optical semiconductor element based on the mounting marker are formed, the driving conductor being a first insulating film formed on a substrate, and It is provided on both of the second insulating films formed to be thicker than one insulating film, and a mounting marker is formed on the first insulating film.

In the method of manufacturing a substrate for mounting an optical component according to the present invention, a V-groove and a mounting marker are formed using a photomask on which a V-groove forming pattern and a mounting marker forming pattern are formed. It is characterized by the following.

Further, the optical module of the present invention is an optical semiconductor device which optically couples an optical waveguide in the V-groove of the optical component mounting substrate and a driving conductor formed in the first insulating film with the optical waveguide. It is characterized by being arranged respectively.

[0016]

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

As shown in FIG. 1, an optical component mounting substrate S according to the present invention is provided with an optical fiber, which will be described later, which is an optical waveguide, on a substrate 1 made of silicon single crystal or the like and having a main surface having a predetermined orientation. V-groove 6 to be set, mounting marker 10 positioned with respect to this V-groove 6, and mounting marker 10
(Hereinafter referred to as a driving conductor for an optical semiconductor element, which will be described later) (7: electrode pattern for mounting the light emitting element, 8a to 8c: electrode pattern for driving the light emitting element, 17: electrode pattern for mounting the light receiving element for monitoring, 18a To 18c: a driving electrode pattern of the light emitting element). In the drawing, reference numeral 9 denotes a solder pattern.

The driving conductor is provided on both the first insulating film 2 formed on the substrate 1 and the second insulating film 4 formed thicker than the first insulating film 2. An opening-shaped mounting marker 10 is formed in the insulating film 2.

Here, the first insulating film 2 is formed to a thickness of about several hundreds to several thousand degrees, is very thin, and is formed so as to easily release heat generated from the optical semiconductor element. When the film is formed, the opening of the mounting marker 10 and the pattern for forming the V-groove 6 are simultaneously formed. The second insulating film 4 is formed to a thickness of about 5 μm to 10 μm,
It is formed thicker than the first insulating film. The reason for this is
If the thickness is less than 5 μm, the electric field is absorbed by the substrate side when driving the optical semiconductor element at a high frequency, and the loss increases. If the thickness is more than 10 μm, it becomes difficult to form a slope described later.

Next, a method of manufacturing the optical component mounting substrate S will be described with reference to FIGS.

First, the upper surface of the substrate 1 is thermally oxidized to form a thermal oxide film. Then, as shown in FIGS. 2A1 and 2A2, the thermal oxide film on the optical fiber mounting portion is removed,
The thermal oxide film 2 only on the side on which the optical semiconductor element is mounted is left. Then, a silicon nitride film 3 is formed on the entire upper surface of the substrate 1.

Next, as shown in FIGS. 2 (b1) and 2 (b2), the V-groove forming pattern is the same on the optical fiber mounting portion, and the mounting marker pattern for the optical semiconductor device is the same on the optical semiconductor device mounting portion. And using the photomask, the silicon nitride film is removed only in these regions to form opening patterns 10 (mounting markers) and 15 (V-groove forming patterns) aligned with high precision. I do.

Next, as shown in FIGS. 2 (c1) and 2 (c2), a thick insulating film is formed on the entire upper surface of the substrate 1 and is thick only under a region where a driving electrode of the optical semiconductor element is formed. An insulating film 4 is formed. At this time, the insulating film 4 to be removed is subjected to isotropic etching.

Next, as shown in FIGS. 2 (d1) and 2 (d2), a protective film 5 made of a silicon nitride film is formed on the entire upper surface of the substrate 1. Here, since the insulating film 4 has been subjected to isotropic etching, the edge portion is formed obliquely. As a result, the protection film 5 made of the silicon nitride film can be protected without interruption at the edge of the thick insulating film 4 or the like.

Next, as shown in FIGS. 3 (e1) and 3 (e2), the protective film 5 made of a silicon nitride film on the optical fiber mounting portion.
Is removed leaving the silicon nitride film 3 formed first, exposing the V-groove forming pattern 15 for mounting an optical fiber formed in FIGS. 2 (b1) and 2 (b2).

Using the V-groove forming pattern 15 for mounting the optical fiber formed on the silicon nitride film 3 as a silicon etching mask, the V-groove 6 for mounting the optical fiber is anisotropically treated with an alkali solution such as potassium hydroxide (KOH). It is formed with high precision by reactive etching.

When the optical fiber mounting V-groove 6 is formed, the mounting marker 10 of the optical semiconductor element is protected by the protective film 5 made of a silicon nitride film, thereby preventing silicon etching below the mounting marker 10. And the shape of the mounting marker 10 can be maintained. As a result, it is possible to produce a complex shape of the mounting marker 10 such that the mounting accuracy is improved when the optical semiconductor element is mounted.

Next, as shown in FIGS. 3 (f1) and (f2), the silicon nitride film 3 in the optical fiber mounting portion and the silicon nitride film 5 in the optical semiconductor device mounting portion are removed. At this time, the silicon nitride film 3 formed on the optical semiconductor element mounting portion is not removed.

Next, as shown in FIGS. 3 (g1) and (g2), the mounting electrode patterns 7, 17 are mounted on the optical semiconductor element mounting portion.
Then, drive electrode patterns 8 and 18 for the optical semiconductor element are formed, and solder 9 for bonding the optical semiconductor element is formed on the electrode patterns 7 and 17 for mounting the optical semiconductor element. The drive electrode patterns 8 and 18 of the optical semiconductor element are shown in FIGS.
The thick second insulating film 4 formed in 2) and a part thereof are formed on the slope and the first insulating film 2 and are connected to the mounting electrode patterns 7 and 17 of the optical semiconductor element. .

Finally, as shown in FIGS. 3 (h1) and (h2), an optical fiber stopper rectangular groove 11 is formed.

Here, an example of the shape of the mounting marker will be described. As shown in FIG. 5A, a circular marker or a ring-shaped marker shown in FIG. 5B may be used, but it can be easily formed into various shapes so as to minimize the occurrence of angular displacement. That is, for example, FIG.
5 (c), and may be an elliptical marker or an elliptical ring marker shown in FIG. 5 (c), or a polygonal marker such as a regular octagon shown in FIG. 5 (e). Alternatively, a polygonal ring-shaped marker shown in FIG.

Next, the optical module of the present invention will be described. As shown in FIG. 4, the optical module M is a drive conductor in which the optical fiber 12 is formed in the V groove 6 of the optical component mounting substrate S obtained by the above manufacturing method, and the first insulating film 2 is formed. A light emitting element 13 is provided on the mounting electrode pattern 7 via the solder pattern 9, and a monitor light receiving element 14 is provided on the mounting electrode pattern 17 via the solder pattern 9, respectively.
Further, these optical semiconductor elements are connected to the driving electrode patterns 8 (8b) and 18 (18b) by bonding wires, so that the light emitting element 13 and the end of the optical fiber 12 can be optically coupled.

Thus, when the optical semiconductor element is driven at high frequency, the loss can be minimized by preventing the driving electric field from reaching the substrate due to the presence of the thick second insulating film. Also, there is no relative displacement between the V-groove for mounting the optical waveguide and the mounting marker of the optical semiconductor element, so that the optical semiconductor element can be mounted with high accuracy, and the mounting accuracy is improved when mounting the optical semiconductor element. A complicated mounting marker can be easily formed. Thereby, an optical module having excellent optical coupling efficiency can be provided.

[0034]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for manufacturing a semiconductor mounting substrate according to the present invention will be described below.

First, a thermal oxide film (silicon oxide film) having a thickness of 1 μm was formed on a substrate made of silicon single crystal. Next, the thermal oxide film around the V-groove for mounting the optical fiber was removed. Next, a silicon nitride film is formed on the entire surface of the substrate by 0.5.
A film was formed to a thickness of μm to form a V-groove pattern for mounting an optical fiber and a marker pattern for mounting. The mounting marker was formed in a portion where the thermal oxide film was not removed. next,
A silicon oxide film as an insulating film having a thickness of 10 μm was formed on the entire surface of the substrate. Isotropic etching was performed except for the portion corresponding to the lower part of the periphery of the optical semiconductor driving electrode.

Next, a silicon nitride film is formed as a protective film to a thickness of 0.5 μm on the entire surface of the substrate, and the silicon nitride film around the optical fiber mounting V-groove pattern is formed to a thickness of 0.5 μm by the thickness of the protective film.
m. Next, silicon is used as KOH (concentration 43% by weight, temperature 60 ° C.) using the V-groove pattern for mounting the optical fiber formed on the silicon nitride film formed first as an etching mask.
C.) to perform anisotropic etching to form an optical fiber mounting V-groove. Next, the protective film made of a silicon nitride film formed on the optical semiconductor mounting electrode, the driving electrode portion and the peripheral portion, and the silicon nitride film of the etching mask for forming the optical fiber mounting V-groove were removed. Next, Ti / Pt / Au is added to the semiconductor mounting and driving electrodes in the order of lower layer / upper layer by 10%.
It was formed in a configuration of 00/2000/2000. Solder (Au80 / Sn20 (thickness: about 3 μm)) was formed on the semiconductor mounting electrode 8. Finally, the optical fiber stopper rectangular groove was machined and cut.

With this, it is possible to form a mounting marker having a complicated shape such that there is no relative displacement between the V-groove for mounting the optical fiber and the optical semiconductor element and the mounting accuracy is improved when mounting the optical semiconductor element. Was completed.

[0038]

As described in detail above, according to the present invention, the driving conductor of the optical semiconductor element is formed on the substrate by the first insulating film and the second insulating film is formed thicker than the first insulating film. Since it is provided on both sides of the insulating film, it is possible to increase the frequency of the electric signal for driving the optical semiconductor element.

Further, since the mounting marker and the V-groove forming pattern of the optical semiconductor element can be formed using the same photomask, the positional relationship between the mounting marker and the V-groove can be manufactured with high precision. Further, it is possible to easily form a complicated mounting marker for improving the mounting accuracy at the time of mounting the optical semiconductor element, and it is possible to provide an optical module having high optical coupling efficiency between the optical semiconductor element and the optical waveguide. .

[Brief description of the drawings]

FIG. 1 is a perspective view schematically illustrating an embodiment of an optical component mounting board according to the present invention.

FIG. 2 is a process diagram illustrating an example of a manufacturing process of the optical component mounting board according to the present invention, wherein (a1) to (d1) are schematic plan views, and (a2) to (d2) are schematic diagrams. FIG.

FIG. 3 is a process diagram illustrating an example of a manufacturing process of the optical component mounting board according to the present invention, wherein (e1) to (h1) are schematic plan views, and (e2) to (h2) are schematic. FIG.

FIG. 4 is a perspective view schematically illustrating an embodiment of the optical module according to the present invention.

5A to 5F are plan views schematically illustrating one embodiment of a mounting marker according to the present invention.

6A and 6B are schematic views illustrating a conventional optical component mounting board, wherein FIG. 6A is a plan view and FIG. 6B is a side view.

FIGS. 7A and 7B are schematic views illustrating a conventional optical component mounting board, wherein FIG. 7A is a plan view and FIG. 7B is a side view.

8A and 8B are schematic diagrams illustrating a conventional optical component mounting board, wherein FIG. 8A is a plan view and FIG. 8B is a side view.

FIGS. 9A and 9B are schematic views illustrating a conventional optical component mounting substrate, wherein FIG. 9A is a plan view and FIG. 9B is a side view.

FIG. 10 is a schematic view showing that the mounting marker is limited to a quadrangular shape in the related art.
(C) is a plan view, and (b) and (d) are cross-sectional views.

FIG. 11 is a schematic view illustrating that in the related art, when the mounting marker is formed simultaneously with the mounting electrode of the optical semiconductor element, the relative position of the mounting marker is shifted with respect to the V-groove for mounting the optical fiber. , (A) and (b) are plan views, respectively.

[Explanation of symbols]

 1: substrate 2: first insulating film 4: second insulating film 5: protective film 6: V groove 7, 17: mounting electrode pattern (driving conductor) 8, 18: driving electrode pattern (driving conductor) 9 : Solder 10: Mounting marker S: Optical component mounting substrate M: Optical module

Claims (3)

[Claims] 1. A V-groove for disposing an optical waveguide on a substrate, a mounting marker positioned with respect to the V-groove, and a driving conductor for disposing an optical semiconductor element based on the mounting marker. Wherein the driving conductor is disposed on both the first insulating film formed on the substrate and the second insulating film formed thicker than the first insulating film. An optical component mounting substrate, wherein the mounting marker is formed on the first insulating film. 2. The optical component according to claim 1, wherein the V-groove and the mounting marker are formed using a photomask on which a V-groove forming pattern and a mounting marker forming pattern are formed. A method for manufacturing a mounting substrate. 3. The V of the optical component mounting board according to claim 1.
An optical module comprising: an optical waveguide in a groove; and an optical semiconductor element for optically coupling the optical waveguide to a driving conductor formed in the first insulating film.