JP3264284B2 - Optical receiving module - 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 receiving module used for optical fiber communication.

[0002]

2. Description of the Related Art As an optical receiving module, IEICE Technical Report Vo
l. 91, No. 201 (OQE91-60 to 68) are known. Conventionally, such an optical receiving module has a structure shown in FIGS.

In the optical receiving module shown in FIG. 6, an IC chip 6 having a light receiving element 4 and a preamplifier circuit formed therein is fixed inside a lower package 2, and an optical fiber 8 has a terminal end facing a light receiving surface of the light receiving element 4. In this way, the package is vertically fixed to the upper package 10, and the lower package 2 and the upper package 10 are sealed to prevent leakage and incidence of light from the outside.

The light transmitted through the optical fiber 8 is received by the light receiving element 4 and converted into an electric signal. The electric signal is further amplified by the preamplifier circuit of the IC chip 6 and output through the lead terminal 12. I do.

On the other hand, in the light receiving module shown in FIG. 7, an IC chip 18 having a light receiving element 16 and a preamplifier circuit formed inside a package 14 having a sealed structure for preventing leakage and incidence of light from the outside. The optical fiber 20 is fixed so that the terminal end of the optical fiber 20 is arranged in parallel with the light receiving surface of the light receiving element 16. Further, the optical fiber 20
Is polished obliquely so that light transmitted through the optical fiber 20 is reflected by the polished surface 22 and is incident on the light receiving surface of the light receiving element 16.

[0006] The electric signal photoelectrically converted by the light receiving element 16 is amplified by a preamplifier circuit of the IC chip 18 and output via a lead terminal (not shown).

[0007]

However, in the conventional optical receiving module having such a structure,
The IC chip, the light receiving element and the optical fiber are individually arranged and fixed on the package to integrate them. The positioning accuracy of each component determines the facing accuracy between the optical fiber and the light receiving element. There is a problem that productivity is not improved because of variations in sensitivity and complicated manufacturing to obtain the prescribed light receiving sensitivity.

Particularly, in an optical receiving module in which a plurality of optical fibers and a plurality of light receiving elements corresponding thereto are arranged in an array to perform parallel communication, the optical coupling between the optical fibers and the light receiving elements is all combinations. Must be excellent and uniform, and therefore, extremely high mechanical accuracy is required, and there has been a problem that sufficient productivity cannot be obtained in terms of yield and the like.

The present invention has been made in view of such a conventional problem, and it is possible to set good and uniform optical coupling between an optical fiber and a light receiving element and to improve productivity. It is an object of the present invention to provide an optical receiving module having a modified structure.

[0010]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention reflects an optical signal to be transmitted by reflecting the optical signal.
Tilted with respect to the optical axis to change the course of the signal
An optical fiber having an end portion provided with a surface;
A semiconductor substrate having a pair of surfaces, and one of the semiconductor substrates
And reflected by the inclined surface of the optical fiber
Light receiving element for receiving the emitted light and the other surface of the semiconductor substrate
A groove in which the optical fiber is disposed;
Positioned with respect to the light receiving element, the end of the optical fiber
Part is abutted and provided on the other surface of the semiconductor substrate.
A terminal step for terminating the groove.
The bar is positioned by the groove and the terminal step, and
The signal passes through the semiconductor substrate and is incident on the light receiving element.
You.

Further, the present invention reflects a transmitted optical signal.
Angle with respect to the optical axis so as to change the course of the optical signal.
Optical fiber having a terminating end provided with a tilted inclined surface.
A bar; a semiconductor substrate having a pair of opposing surfaces;
The optical fiber is provided on one surface of the conductive substrate, and is tilted.
Multiple light receivers each receiving light reflected by the slope
An element, provided on the other surface of the semiconductor substrate;
A plurality of grooves in which optical fibers are respectively arranged;
An optical fiber positioned with respect to each of the light receiving elements;
Of the semiconductor substrate
And a terminal step portion provided on the surface for terminating each groove.
Each of the optical fibers is formed by the respective groove and the terminal step.
Respectively, and the optical signal is transmitted through the semiconductor substrate.
The light passes through and enters the light receiving elements.

Further, the groove is formed by a photomask and an etching process.

[0013]

According to this structure, the optical signal transmitted through the optical fiber fixed to the groove is reflected by the inclined surface and is incident on the light receiving element from the back side of the semiconductor substrate. It is possible to realize extremely high-precision optical coupling between them, and furthermore, it is possible to eliminate mechanically movable parts, so that it is excellent in durability.

Further, by manufacturing by applying a well-known planar process or the like, since the above-mentioned grooves can be formed with high positioning accuracy, the characteristics can be easily improved and uniformity can be easily achieved. Performance can be improved. Further, by fixing the optical fiber to the terminal step of the groove, the fixing position of the optical fiber can be easily determined.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the optical receiving module according to the present invention will be described below with reference to the drawings.

FIG. 1 shows a basic optical receiving module for receiving an optical signal transmitted by one optical fiber by one light receiving element. In FIG. 1, a light receiving element 26 is provided on the upper surface of a semiconductor substrate 24 made of indium-phosphorus crystal, and an optical fiber 30 is fitted and fixed in a long groove 28 formed on the back surface of the semiconductor substrate 24, and is transmitted by the optical fiber 30. The optical signal is incident on the light receiving element 26 on the upper surface from the back surface side of the semiconductor substrate 24.

Here, the light receiving element 26 is basically a pin formed by forming a pn junction in a gallium-indium-arsenic layer.
A type photodiode or an avalanche photodiode is applied, and the light receiving diameter is set to about 30 μm to 80 μm.

The long groove 28 is formed on the back surface of the semiconductor substrate 24 to a depth of about 50 μm by etching by chemical wet etching, and the terminal step 32 of the long groove 28 is substantially suspended from the light receiving surface of the light receiving element 26. Designed to be a position.

An inclined surface 34 of about 45 ° is formed at the end of the optical fiber 30 by polishing, so that the optical signal transmitted through the optical fiber 30 is reflected by the inclined surface 34 and emitted toward the side end. It has become. Further, the optical fiber 30 is fitted into the long groove 28, and the end of the optical fiber 30 is positioned by contacting the terminal step 32 of the long groove 28, and the optical signal transmitted through the optical fiber 30 is reflected by the inclined surface 34. The inclined surface 34 faces outward so as to radiate in the direction of the light receiving surface of the light receiving element 26, and the optical fiber 30 is fixed in the long groove 28 by a thermosetting adhesive or solder 36 as shown in FIGS. are doing.

The light receiving element 26 and the optical fiber 30
Is housed in a package (not shown) having a sealed structure so as to prevent light from entering from outside, and furthermore, the light receiving element 26 amplifies the electric signal photoelectrically converted. An IC chip (not shown) on which a preamplifier circuit is formed is also provided in the package at the same time.

Next, the manufacturing process of the optical receiving module having such a structure will be described with reference to the flowchart of FIG.

First, in the first step A, the semiconductor substrate 24
Using a double-sided mask aligner, a photoresist is applied to the remaining surface excluding the surface on which the long groove 28 is to be formed.
The end of the long groove 28 is designed to be located at a position substantially facing the light receiving surface of the light receiving element 26.

In the next second step B, using the photoresist as an etching mask, a portion other than the photoresist is made to a thickness of about 50 μm by chemical wet etching using, for example, an etching solution composed of sulfuric acid and hydrogen peroxide.
After etching to a depth to a minimum, the photoresist is removed.
By this processing, the long groove 28 is formed.

In the next third step C, the optical fiber 30
The optical fiber 30 is fitted into the long groove 28, fixed to the back surface of the semiconductor substrate 24 with an adhesive or the like, and further embedded in a package. Completes the assembly process.

According to the structure of this embodiment and the processing steps, the opposing accuracy between the light receiving element 26 and the inclined surface 34 can be easily determined by a well-known basic planar process or the like.
Since the distance can be set within μm, it is possible to realize extremely high-precision optical coupling between the optical fiber 30 and the light receiving element 26, and further, it is possible to eliminate mechanically movable parts. Also has excellent durability.

Next, another embodiment will be described with reference to FIG.
In this embodiment, the manufacturing process is performed in the same manner as in the first embodiment described above so as to face the light receiving surfaces of the respective light receiving elements of the plurality of light receiving element groups 40 provided in an array on the upper surface of the semiconductor substrate 38. By applying this, a plurality of long grooves are formed on the back surface of the semiconductor substrate 38, and the optical fiber group 42 is formed in these long grooves.
Is fixed.

At the end of each optical fiber of the optical fiber group 42, an inclined surface is formed in the same manner as shown in FIG. 1, and an optical signal transmitted through each optical fiber fixed to each long groove is transmitted to these optical fibers. The light is reflected by the inclined surface and is incident on a predetermined light receiving element. Then, the electric signal photoelectrically converted by each light receiving element is amplified by a preamplifier circuit provided independently and output to a predetermined lead terminal via a bonding wire, and further, the whole is supplied with external light. It is housed in a sealed package that blocks incidence.

As shown in this embodiment, the present invention can be applied to an optical receiving module that processes a plurality of optical communications in parallel.
An object of the present invention is to provide an excellent technique for realizing a parallel processing type optical receiving module having excellent optical coupling and durability.

[0029]

As described above, according to the present invention,
A light-receiving element provided on one surface of the semiconductor substrate, a groove formed on the back surface of the semiconductor substrate facing the light-receiving element, and the light received by reflecting transmitted light on an inclined surface formed at a terminal end. An optical fiber fixed in the groove arranged so as to be incident on the light receiving surface of the element from the back surface side of the semiconductor substrate, and an optical signal transmitted through the optical fiber fixed in the groove is reflected on the inclined surface. The structure allows light to enter the light-receiving element from the back side of the semiconductor substrate, so that extremely high-precision optical coupling between the optical fiber and the light-receiving element can be realized, and further, mechanically movable parts are eliminated. It is excellent in durability because it can be.

Further, by manufacturing by applying a well-known planar process or the like, the above-mentioned grooves can be formed with high positioning accuracy, so that the characteristics can be easily improved and uniformized, and the productivity can be improved. Can be achieved. In particular,
When applied to a parallel processing type optical receiving module that requires excellent optical coupling and durability, an extremely excellent technique can be provided.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a longitudinal sectional structure of a main part of one embodiment.

FIG. 2 is a sectional view taken along line XX of FIG.

FIG. 3 is a rear view showing a structure as viewed from the back surface of the semiconductor substrate of one embodiment.

FIG. 4 is a flowchart for explaining a manufacturing process.

FIG. 5 is a perspective view showing an external structure of another embodiment.

FIG. 6 is a sectional view schematically showing a structure of a conventional example.

FIG. 7 is a sectional view schematically showing a structure of another conventional example.

[Explanation of symbols]

24, 38: semiconductor substrate, 26: light receiving element, 28: long groove, 30: optical fiber 32: terminal step, 34: inclined surface, 40: light receiving element group, 4
2. Optical fiber group

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 31/02-31/024 G02B 6/42

Claims (3)

(57) [Claims] An optical signal to be transmitted is reflected to reflect the optical signal.
The inclined surface inclined to the optical axis to change the course
A fiber-optic having an end portion provided a semiconductor substrate having a pair of opposed faces, a surface on the other hand of the semiconductor substrate, the optical fiber
A light receiving element for receiving the light reflected by the inclined surface of the chromatography, provided on the other surface of said semiconductor substrate, said optical fiber
A groove over is located, it is positioned with respect to the light receiving element, the optical fiber
Of the semiconductor substrate is abutted against the other surface of the semiconductor substrate.
Provided with a termination step portion for terminating said groove, the optical fiber over, the groove and the end step portion and the position
Is Me-decided, the optical receiver module, wherein the optical signal is incident on <br/> the light receiving element passes through the semiconductor substrate. 2. An optical signal to be transmitted is reflected to reflect the optical signal.
The inclined surface inclined to the optical axis to change the course
A plurality of fiber-optic having an end portion provided a semiconductor substrate having a pair of opposed faces, a surface on the other hand of the semiconductor substrate, each of said optical fiber
A plurality of light receiving elements respectively receiving light reflected by the inclined surface of the bar; and a plurality of light receiving elements provided on the other surface of the semiconductor substrate.
Aiba is positioned a plurality of grooves are arranged respectively, for each of said light receiving element, the optical file
Of the semiconductor substrate
And a termination step portion for terminating the respective grooves provided on the other surface of the plate, each fiber-optic can the each groove and the termination step portion
Ri is positioned respectively, the optical signal is the semiconductor substrate
A light receiving module that passes through the inside of the light receiving element and is incident on each of the light receiving elements. 3. The optical receiving module according to claim 1, wherein the groove is formed by a photomask and an etching process.