JPH0537087A - Optical semiconductor device - Google Patents

Abstract

PURPOSE:To provide an optical semiconductor device which can set with high precision a recess depth for installing a semiconductor laser provided on a semiconductor substrate and accurately optically couple a semiconductor laser and an optical fiber on the semiconductor substrate. CONSTITUTION:A recess 10a and a V-groove 10b are formed in a semiconductor substrate 10, where a semiconductor laser 30 is installed in the recess 10a, and an optical fiber 20 in the V-groove 10b to optically couple the semiconductor laser 30 and the optical fiber 20. The semiconductor substrate 10 is constituted of an adhesive substrate 10 comprising two silicon wafers 11, 13 adhered through a silicon oxide film 12: one wafer 13 of this adhesive substrate 10 is selectively etched until reaching the silicon oxide film 12 to form the recess 10a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical semiconductor device in which an optical semiconductor element such as a semiconductor laser and an optical component such as an optical fiber are installed on a semiconductor substrate and these are optically coupled to each other. The present invention relates to an optical semiconductor device having improved mounting means on a substrate.

[0002]

2. Description of the Related Art Conventionally, semiconductor lasers, light emitting diodes,
To couple an optical semiconductor device such as a photodiode to an optical fiber, fix the optical fiber in a groove formed on the silicon substrate and attach the optical semiconductor device to the silicon substrate so that the optical fiber is optically coupled. ing.
In this way, since the V-groove formed by anisotropic etching of the silicon substrate can be used for fixing the optical fiber, the positional accuracy of the optical fiber with respect to the substrate becomes high.

On the other hand, as a method for positioning and fixing the optical semiconductor element, a recess is formed in one of the optical semiconductor element and the silicon substrate.
A method is known in which a convex portion is formed on the other side, and the convex portions are combined and integrated (JP-A-55-157277). At this time, the convex portion or the concave portion can be accurately formed by using anisotropic etching, anisotropic epitaxial growth, or the like.

7 and 8 show a conventional example of this type of apparatus. FIG. 7 is a perspective view showing the overall structure, FIG. 8A is a sectional view taken along the line AA 'of FIG. 7, and FIG. 7B) is a sectional view taken along line BB ′ of FIG. 7. In this conventional example, a trapezoidal convex portion 3a is formed on the semiconductor laser 3, an inverted trapezoidal concave portion 1a having the same size and shape as the convex portion 3a is formed on the substrate 1, and the convex portion 3a and the concave portion 1a are formed. By combining them correctly, it is possible to perform accurate alignment between the substrate 1 and the semiconductor laser 3 and perform highly accurate bonding. Further, if the positional relationship between the V groove 1b that determines the position of the optical fiber 2 and the concave portion 1a is accurately determined, the optical coupling between the optical fiber 2 and the semiconductor laser 3 can be performed with high accuracy.

In this case, the front, rear, left and right alignment of the semiconductor laser 3 on the substrate 1 is performed by aligning the respective convex portions 3a.
The precision is very high because it depends on the precision of lithography when forming a selective etching mask or the like for forming the recess 1a. On the other hand, the vertical alignment with the substrate 1 is determined by the etching conditions and the epitaxial growth conditions when forming the protrusions 3a or the recesses 1a, but it is difficult to control these conditions accurately. Yes, the alignment accuracy is not necessarily high.

For example, when the inverted trapezoidal concave portion 1a is provided on the silicon substrate 1 and the trapezoidal convex portion 3a is provided on the semiconductor laser 3, the concave portion 1a of the silicon substrate 1 is higher than the convex portion 3a of the semiconductor laser 3. If it is shallower than that, the height of the light emitting portion of the semiconductor laser 3 will be higher than designed.
On the contrary, the concave portion 1a of the silicon substrate 1 has the semiconductor laser 3
If the height is lower than the height of the convex portion 3a, a gap is formed between the convex portion 3a and the concave portion 1a, and bonding cannot be performed. The same problem applies to the controllability of the height of the convex portion or the depth of the concave portion provided in the semiconductor laser.

[0007]

As described above, in the conventional optical semiconductor device in which an optical semiconductor element such as a semiconductor laser and an optical component such as an optical fiber are optically coupled on a semiconductor substrate,
The controllability of the height of the convex portion or the depth of the concave portion provided for combining the optical semiconductor element and the semiconductor substrate is poor, and the optical semiconductor element and the optical component cannot be accurately optically coupled, or the optical semiconductor element and the semiconductor substrate are There was a problem that bonding could not be done well.

The present invention has been made in consideration of the above circumstances, and an object of the present invention is to set the depth of a concave portion or the height of a convex portion provided on a semiconductor substrate with high accuracy. An object of the present invention is to provide an optical semiconductor device capable of accurately optically coupling an optical semiconductor element and an optical component on a substrate.

[0009]

The essence of the present invention is to use, as a semiconductor substrate, an adhesive substrate in which two semiconductor wafers are bonded together via an insulating film.

That is, according to the present invention, a concave portion is formed on one of the semiconductor substrate and the optical semiconductor element, and a convex portion is formed on the other, and the concave portion and the convex portion are fitted together to integrate the semiconductor substrate and the optical semiconductor element, and the semiconductor substrate is formed. In an optical semiconductor device in which an optical component formed or fixed to the substrate and an optical semiconductor element are optically coupled to each other, the semiconductor substrate is composed of an adhesive substrate obtained by adhering two semiconductor wafers with an insulating film interposed therebetween. One of the wafers is selectively etched until it reaches the insulating film to form a concave portion or a convex portion.

Further, the following (1) to (3) are mentioned as preferred embodiments of the present invention. (1) Silicon wafers are used as the two semiconductor wafers forming the adhesive substrate, and a silicon oxide film is used as the insulating film. (2) An optical fiber is used as an optical component, and a V groove for fixing the optical fiber is provided on the adhesive substrate. (3) The constituent substrate of the optical semiconductor element and the silicon wafer are directly adhered to each other, and a part of the element constituent substrate is selectively etched until reaching the silicon wafer to provide a concave portion or a convex portion.

[0012]

In the present invention, as the semiconductor substrate for fixing the optical semiconductor element and the optical component, the adhesive substrate in which two semiconductor wafers are directly adhered via the insulating film is used. It is possible to automatically stop the etching of the semiconductor on the surface of the insulating film. Therefore, the depth of the concave portion to be formed or the height of the convex portion can be determined only by the thickness of the semiconductor wafer before being bonded. Therefore, the height of the light emitting portion of the optical semiconductor element can be controlled as designed, and the optical coupling between the optical semiconductor element and the optical component becomes easy. Further, there is no possibility that a gap is formed between the convex portion and the concave portion and the optical semiconductor element and the semiconductor substrate cannot be properly bonded.

Similarly, if the optical semiconductor element is formed on the compound semiconductor substrate directly bonded to the semiconductor wafer, the height or depth of the convex portion or the concave portion provided on the optical semiconductor element can be accurately determined by selective etching. It can be processed well.

[0014]

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

FIG. 1 is a perspective view showing a schematic structure of an optical semiconductor device according to the first embodiment of the present invention, and FIG. 2 is a line A- in FIG.
It is an A'sectional view. In the figure, 10 is an adhesive substrate in which two silicon wafers are directly adhered, and a concave portion 10a for mounting an optical semiconductor element and a V groove 10b for installing an optical fiber are formed on the upper surface of the adhesive substrate 10. There is. A semiconductor laser (optical semiconductor element) 30 in which a concave portion 10a of the adhesive substrate 10 is provided with a convex portion 30a corresponding to the concave portion 10a.
Is installed. Further, an optical fiber (optical component) 20 is installed in the V groove 10b so that the semiconductor laser 30 and the optical fiber 20 are optically coupled.

More specifically, the adhesive substrate 10 is formed by adhering two silicon wafers 11 and 13 via a silicon oxide film 12, and the concave portion 1 is formed on the upper surface of the adhesive substrate 10.
Fusing material thin film (electrode) such as gold / tin alloy including 0a 14
Are formed.

In order to form the adhesive substrate 10 having the recess 10a, a silicon oxide film (SiO ₂ ) 12 is first formed on a silicon wafer 11 as shown in FIG.
Another silicon wafer 13 is bonded thereon and heat-treated to form the adhesive substrate 10. Then, FIG.
As shown in (b), a silicon nitride mask 17 is deposited on the adhesive substrate 10, and a hole is made in a portion where a semiconductor laser is fixed by a lithography technique. Then, as shown in FIG. 3C, the silicon wafer 13 is anisotropically etched. After that, by removing the silicon nitride mask 17,
As shown in FIG. 3D, the adhesive substrate 10 having the recess 10a can be obtained.

Here, the etching of silicon shown in FIG. 3C can be automatically stopped when the silicon oxide film 12 is reached. Therefore, if the thickness of the silicon wafer 13 is adjusted to match the height of the convex portion 30a of the semiconductor laser 30, the vertical height of the light emitting portion of the semiconductor laser 30 with respect to the adhesive substrate 10 is uniquely determined. be able to. If a narrow opening is provided in the silicon nitride mask 17, V for installing the optical fiber 20 can be provided.
The groove 10b can be formed at the same time.

On the other hand, the semiconductor laser 30 is an InGaAsP type laser (oscillation wavelength 1.3
μm) on the n-InP substrate 31, the n-InP clad layer 32, the non-doped InGaAsP active layer 33, p.
A silicon oxide film (SiO ₂ ) 3 having a convex portion 30a formed of the InP clad layer 34 and the InGaAs contact layer 35 and having a stripe opening on the convex portion 30a side.
6 and Au / AuZn to form a p-side electrode 37,
Further, an n-side electrode 38 made of Au / AuGe is formed on the lower surface of the substrate 31. Each of the layers 32 to 35 of the semiconductor laser 30 is selectively crystallized by using a metal organic chemical vapor deposition method by providing a SiO ₂ mask (not shown) having a stripe-shaped opening on the n-InP substrate 31. grown. The semiconductor laser 30 has a convex portion 30a.
With the side facing down, the convex portion 30a is fixed so as to be fitted into the concave portion 10a of the adhesive substrate 10, and the electrode 37 on the semiconductor laser 30 side and the electrode 14 on the adhesive substrate 10 side are bonded and connected. .

As described above, according to this embodiment, as the semiconductor substrate, the adhesive substrate 10 in which the two silicon wafers 11 and 13 are adhered via the silicon oxide film 12 is used, and one silicon wafer 13 is attached to the silicon oxide film 12. Since the recesses 10a are provided by selective etching until the depth reaches, it is possible to set the depth of the recesses 10a with good controllability. For this reason, the semiconductor laser 30 with respect to the substrate 10 can have extremely high alignment accuracy in the vertical direction as well as alignment accuracy in the horizontal direction. Therefore, an optical semiconductor device having the optical fiber 20 and the semiconductor laser 30 optically coupled on the substrate 10 can be easily manufactured, and the manufacturing yield can be remarkably improved.

FIG. 4 is a sectional view showing a schematic structure of an optical semiconductor device according to the second embodiment of the present invention. Note that FIG.
The same parts as those of the above are denoted by the same reference numerals, and detailed description thereof will be omitted.

This embodiment is different from the first embodiment described above in that the convex portion 10c is provided on the substrate 10 side and the concave portion 30b is provided on the semiconductor laser 30 side. The protrusion 10c may be formed on the adhesive substrate 10 in the same manner as in the first embodiment. On the other hand, the recess 30 is formed in the semiconductor laser 30.
To form b, an InP layer 39 is grown on a normal semiconductor laser structure wafer (31 to 35 in this embodiment), an SiO ₂ mask having stripe-shaped openings is formed, and the openings are formed. The InP layer 39 can be formed by anisotropic selective etching.

Even with such a structure, by using the adhesive substrate 10 in which two silicon wafers 11 and 13 are adhered via the silicon oxide film 12, the height of the convex portion 10c provided on the adhesive substrate 10 can be increased. It can be set with good controllability. Therefore, the same effect as that of the first embodiment can be obtained.

FIG. 5 is a sectional view showing a manufacturing process of an optical semiconductor device according to the third embodiment of the present invention. Although details of the optical semiconductor element are not shown in this embodiment, they are almost the same as those shown in FIG.

First, as shown in FIG. 5A, a double heterojunction is formed on the InP substrate 31 directly bonded on the Si wafer 51 in the same manner as in the first embodiment, and the semiconductor laser 30 is formed. To create. With this structure, the convex portion 30a of the semiconductor laser 30 can be formed by etching. That is, as shown in FIG. 5B, the InP substrate 3
1 (more accurately, the substrate 31, the layers 32 to 35, the silicon oxide film 36, and the electrode 37 formed on the substrate 31) are selectively etched so as to leave a stripe shape.
The convex portion 30a made of the nP substrate 31 is formed.

In this case, since the etching can be automatically stopped at the InP / Si interface, the height of the light emitting portion in the semiconductor laser 30 can be accurately controlled by adjusting the thickness of the InP substrate 31. can do. The epitaxial growth process for producing the semiconductor laser 30 can be performed either before or after the etching process.

The semiconductor laser 30 having the convex portion 30a thus formed is placed in the concave portion 10a of the adhesive substrate 10 as shown in FIG. 5C, so that the same operation as in the first embodiment is performed. The optical semiconductor device is completed.

FIG. 6 is a sectional view showing a manufacturing process of an optical semiconductor device according to the fourth embodiment of the present invention. This embodiment differs from the third embodiment in that a recess is provided on the semiconductor laser side.

First, as shown in FIG. 6A, a laser element is formed on the InP substrate 31 directly bonded to the Si wafer 51. Then, as shown in FIG.
Part of the substrate 31 is selectively etched to form the recess 30b. Next, as shown in FIG. 6C, the semiconductor laser 30 having the concave portion 30b is placed on the convex portion 10c of the adhesive substrate 10 to complete the optical semiconductor device as in the second embodiment.

The present invention is not limited to the above embodiments. In the embodiment, the semiconductor laser is used as the optical semiconductor element, but the present invention is not limited to this, and a light emitting diode, a photodiode or the like may be used. Also,
The optical component is not limited to the optical fiber, but other optical semiconductor elements fixed on the semiconductor substrate can be used, and further, it can be applied to an optical waveguide formed on the semiconductor substrate itself. The semiconductor wafer forming the adhesive substrate is not limited to silicon, and any semiconductor that can be directly adhered may be used. Further, the insulating film interposed between the semiconductor wafers is not limited to SiO ₂ and may be SiON, Si ₃ N ₄ or the like. In addition, various modifications can be made without departing from the scope of the present invention.

[0031]

As described above in detail, according to the present invention, as a semiconductor substrate on which an optical semiconductor element and an optical component optically coupled to the optical semiconductor element are mounted, two semiconductor wafers are bonded to each other with an insulating film interposed therebetween. By using, it is possible to set the depth of the concave portion or the height of the convex portion provided on the semiconductor substrate with high accuracy, and it is possible to accurately optically couple the optical semiconductor element and the optical component.

[Brief description of drawings]

FIG. 1 is a perspective view showing a schematic configuration of an optical semiconductor device according to a first embodiment of the present invention,

2 is a sectional view taken along the line AA ′ of FIG.

FIG. 3 is a cross-sectional view showing a manufacturing process of the adhesive substrate used in the first embodiment,

FIG. 4 is a sectional view showing a schematic configuration of an optical semiconductor device according to a second embodiment of the present invention,

FIG. 5 is a sectional view showing a manufacturing process of an optical semiconductor device according to a third embodiment of the present invention,

FIG. 6 is a sectional view showing a manufacturing process of an optical semiconductor device according to a fourth embodiment of the present invention,

FIG. 7 is a perspective view showing a schematic configuration of a conventional optical semiconductor device,

FIG. 8 is a view showing a cross section taken along the line AA ′ and the cross section taken along the line BB ′ of FIG. 7;

[Explanation of symbols]

 10 ... Adhesive substrate, 10a ... Recessed portion, 10b ... V groove, 10c ... Convex portion, 11, 13, 51 ... Silicon wafer (semiconductor wafer), 12 ... Silicon oxide film, 17 ... Silicon nitride mask, 20 ... Optical fiber (optical Parts), 30 ... semiconductor laser (optical semiconductor element), 30a ... convex portion, 30b ... concave portion.

Claims (1)

Claim: What is claimed is: 1. An adhesive substrate comprising two semiconductor wafers bonded together via an insulating film, one wafer being selectively etched until reaching the insulating film to form a concave portion or a convex portion. And an optical semiconductor element which has a convex portion or a concave portion corresponding to the concave portion or the convex portion of the adhesive substrate and which is integrated with the substrate by fitting the concave portion and the convex portion, and formed on the substrate or fixed to the substrate Was
An optical semiconductor device comprising the optical semiconductor element and an optical component optically coupled.