JP2002344057A - Semiconductor light-emitting element module subassembly - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser diode module subassembly, in which optical parts, such as ball lens or the like, can be attached easily to a silicon board, with high positional accuracy. SOLUTION: This module subassembly is provided with a laser diode 2 for emit light, a ball lens 3 located on the optical path of the light emitted from the laser diode 2, a silicon substrate 1 provided with the laser diode 2 and ball lens 3 on its main surface, and a plate spring 4 pinching the ball lens 3 with the main surface of the silicon substrate 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor light emitting element module subassembly incorporated in a semiconductor light emitting element module used in an optical communication device, and more specifically, to a submount substrate for an optical component such as a condenser lens. Related to the fixing structure to

[0002]

2. Description of the Related Art In a conventional semiconductor light emitting element module represented by a laser diode module, as a method of attaching a condensing lens, bonding with a resin-based adhesive, soldering with glass solder, or the like has been common. However, since the condenser lens requires high mounting position accuracy,
In this method, it was difficult to attach a condenser lens at a predetermined position, and the yield was very poor. Further, even if it is mounted at a predetermined position, there is a disadvantage that the position of the condenser lens moves due to a temporal change of heat history or the like, and the parallelism or angle shift of output light occurs.

In order to solve this problem, there has been proposed a structure of a laser diode module having a sectional structure as shown in FIG. 6 (Japanese Patent Application Laid-Open No. 58-98884). In this laser diode module, a laser diode 102, which is a semiconductor light emitting element, includes a conductor film 109 formed on a main surface of a submount substrate 101 such as a silicon substrate.
And the other main surface is mounted on a laser diode mounting jig 111. The laser diode mounting jig 111 is provided with a conical concave portion, and a hole 112 for introducing laser light emitted from the laser diode is provided at the apex of the cone. In this structure, the ball lens 103 as the light condensing means is fitted into the concave portion, and the ball lens 103 is pressed and fixed using the leaf spring 104 as the fixing member.

In the above structure, the condensing lens can be easily mounted by providing a concave portion for fitting the converging lens into the laser diode mounting jig and a leaf spring for pressing the condensing lens. Position adjustment is also easy. Further, the position does not shift due to a temporal change due to a heat history or the like. However, in this structure, since the laser diode and the condenser lens are separately fixed to the submount substrate and the laser diode mounting jig, the miniaturization of the laser diode module has been hindered.

In order to solve the above problem, a method has been developed in which a ball lens is directly fixed to a silicon substrate as a submount substrate. FIG. 7 is a perspective view showing the structure of this type of laser diode module subassembly, and FIG. 8 is a cross-sectional view taken along the line BB 'in FIG.
In this laser diode module subassembly,
The laser diode 102 is mounted on the main surface of the silicon substrate 101 via the solder 108 to form a concave portion 101a on the surface of the silicon substrate 101 in the laser light emission direction of the laser diode 102, and a ball lens 103 is formed in the concave portion 101a. Is arranged. This ball lens 103
Is fixed as follows.
Generally, a method is used in which an aluminum thin film layer 109 is formed on the surface a, and the aluminum thin film layer 109 and the ball lens 103 are thermocompression-bonded by a compression member 113 made of aluminum compound such as Al ₂ O ₃ —Al.

With this structure, not only can a condenser lens with higher positional accuracy be mounted, but also the size of the laser diode module can be reduced.

[0007]

However, in the above-described laser diode module subassembly, since the condenser lens is bonded to the aluminum thin film layer by thermocompression bonding, the bonding strength depends on the state of the aluminum thin film layer and the annealing process. It has been difficult to obtain a stable and highly reliable laser diode module subassembly. Also, since the above structure requires high temperature annealing (annealing) and thermocompression bonding, optical components such as a condenser lens and an optical isolator are mounted on the silicon substrate before soldering the laser diode to the silicon substrate. It is necessary to keep. However, since a laser diode is an element with a very low yield, mounting a condenser lens on a silicon substrate before mounting it requires disposing even the condenser lens if the laser diode is defective. However, this has led to an increase in manufacturing costs. Further, since the temperature at which the condenser lens is bonded is as high as about 350 ° C., the silicon substrate cannot be heated to about 350 ° C. in the subsequent steps. Therefore, when soldering the laser diode to the silicon substrate, a low-melting-point solder, which is liable to creep, must be used, which has been a hindrance to manufacturing a highly reliable laser diode module subassembly.

Accordingly, a main object of the present invention is a structure in which a semiconductor light emitting element and an optical component such as a condenser lens are mounted on a sub-mount substrate. An object of the present invention is to provide a semiconductor light emitting element module subassembly that can be attached. Another object of the present invention is to provide an inexpensive and highly reliable semiconductor light emitting element module subassembly.

[0009]

According to the present invention, there is provided a semiconductor light emitting element module subassembly having a main surface including a semiconductor light emitting element and a condensing lens positioned on an optical path of light emitted by the semiconductor light emitting element. And a fixing member attached to the submount substrate and holding the condenser lens between the submount substrate and the main surface.

With the semiconductor light-emitting element module subassembly having this configuration, the condensing lens can be easily fixed on the main surface of the submount substrate by the fixing member. As a result, the operation of attaching the condenser lens can be performed at room temperature, so that the semiconductor light emitting element does not shift in position and no stress is applied to the semiconductor light emitting element due to heat history. In addition, since it is not necessary to use a low melting point solder for mounting the semiconductor light emitting element on the submount substrate, there is no axial displacement due to creep after a long period of time. Furthermore, since the process of raising and lowering the temperature, which is conventionally required, is not required, the condenser lens can be mounted in a short time.

In the semiconductor light emitting element module subassembly of the present invention, for example, the fixing member has an elastic portion,
It is desirable that the condensing lens be sandwiched between the elastic portion and the main surface of the submount substrate by exerting elastic force (claim 2).

According to this structure, since the fixing member has the elastic portion, the stress applied to the condenser lens can be adjusted to a range in which birefringence does not occur. Therefore, the polarization state can be maintained even after light is transmitted. It becomes possible.

The semiconductor light-emitting element module subassembly of the present invention is located, for example, on the optical path of emitted light.
A reverse light attenuating means for suppressing transmission of light traveling backward on the optical path, and an elastic member attached to the submount substrate and sandwiching the reverse light attenuator between the main surface of the submount substrate. (Claim 3).

With this configuration, the backward light attenuating means, which has been difficult to mount on the submount substrate, can be easily mounted by the elastic member. Thereby, the same effect as the above-described attachment of the condenser lens can be obtained also in the attachment of the backward light attenuating means.

In the semiconductor light emitting element module subassembly of the present invention, for example, the fixing member has a band shape,
A locking piece having both ends folded is provided, and the locking piece is attached to the submount substrate by engaging with a peripheral portion of a main surface opposite to the main surface of the submount substrate. ).

According to this configuration, the fixing member can be easily fixed to the submount substrate. In addition, by fixing with the locking pieces provided at both ends of the fixing member, it is possible to easily mount the fixing member without requiring a complicated configuration.

In the semiconductor light emitting element module subassembly of the present invention, for example, the fixing member is made of metal,
The submount substrate has a metal thin film layer area on its main surface,
It is desirable that a fixing member is attached to a metal piece placed on the metal thin film layer region (claim 5).

According to this structure, the shape of the fixing member can be reduced in size, and the structure becomes simple, leading to a reduction in cost. Further, since the mounting position accuracy of the metal piece is not required, the degree of freedom in mounting the metal piece increases. In addition, even when a plurality of optical components such as a condenser lens and a backward light attenuating unit are mounted, the metal thin film layer and the metal piece used for the mounting can be commonly used.
Ease of operation and shortening of manufacturing time are achieved, and manufacturing cost can be reduced.

In the semiconductor light emitting element module subassembly of the present invention, for example, the fixing member is desirably attached to the metal piece by welding.

According to this configuration, attachment of the fixing member to the metal piece becomes easy. In the semiconductor light emitting element module subassembly of the present invention, for example, the semiconductor light emitting element is a laser diode.

The present invention is particularly effective for a laser diode module equipped with a laser diode.

[0022]

An embodiment of the present invention will be described with reference to the drawings.

(Embodiment 1) FIG. 1 is a schematic perspective view showing the structure of a laser diode module subassembly according to Embodiment 1 of the present invention, and FIG. 2 is a cross-sectional view taken along the line AA 'in FIG. FIG. FIG. 3 is a schematic perspective view showing the structure of the leaf spring.

First, the structure of the laser diode module subassembly according to the present embodiment will be described. In FIG. 1, a laser diode 2 as a semiconductor light emitting element is mounted by solder 8 on an aluminum thin film layer 9 formed on a main surface of a silicon substrate 1 as a submount substrate diced to a predetermined size. . The main surface of the silicon substrate 1 is provided with a groove 1a at a predetermined position, and the ball lens 3 as a condenser lens is provided with the groove 1a.
Is located inside. The groove 1a is formed by a fine processing technique such as anisotropic etching in the manufacturing process of the silicon substrate 1.

The ball lens 3 disposed in the groove 1a
Is fixed to the silicon substrate 1 by the leaf spring 4 being extrapolated to the silicon substrate 1. Referring to FIG. 3, the leaf spring 4 is made of a band-shaped thin metal plate with high elasticity.
At both ends, hook-shaped locking pieces 4a are provided. By the locking piece 4a, the leaf spring 4 is locked to the main surface of the silicon substrate 1 opposite to the main surface on which the ball lens 3 is arranged, so that the ball lens 3 is pressed toward the silicon substrate 1. Has been fixed. When pressing the ball lens 3, it is important to appropriately design the pressing force of the leaf spring 4 on the ball lens 3. The appropriate pressing force is a pressing force that is strong enough to prevent the ball lens 3 from detaching from the silicon substrate 1 due to vibration or impact, and is weak enough not to cause birefringence due to the photoelastic effect of the ball lens 3.

The above-mentioned laser diode 2 is positioned with high precision by self-alignment of the solder 8 used for mounting. The ball lens 3 is also positioned with high precision by the groove 1a and the leaf spring 4 provided on the silicon substrate 1. Therefore, the positional relationship between the laser diode 2 and the ball lens 3 with respect to the silicon substrate 1 can be mounted at a desired position with an accuracy of about 0.5 μm or less. This positional accuracy is a necessary and sufficient performance for incorporating the present laser diode module subassembly into a communication device.

With the above arrangement, by fixing the ball lens with a leaf spring having high elasticity, the stress applied to the ball lens can be easily controlled within a range in which birefringence due to photoelasticity does not occur. The polarization state can be maintained even after transmission through the lens.

Next, a process of mounting the laser diode and the ball lens of the laser diode module subassembly on the silicon substrate will be described.

After heating the silicon substrate 1 to about 350 ° C., the laser diode 2 is made of Au—S having a melting point of about 280 ° C.
It is mounted at a predetermined position on the silicon substrate 1 by the solder 8 made of n. Thereafter, the ball lens 3 is moved to the silicon substrate 1
Is fixed by a leaf spring 4 in a groove 1a formed on the main surface of the main body.

The step of fixing the ball lens is performed at room temperature, unlike the conventional thermocompression bonding step. For this reason,
There is no displacement of the laser diode or stress due to thermal history. Also, since there is no need to raise or lower the temperature, the operation time is greatly reduced. Further, since it is not necessary to use solder having a low melting point when mounting the laser diode, there is no fear of axial misalignment due to creep after a long period of time. In addition, since the laser diode can be mounted on the silicon substrate before the ball lens,
Even if the laser diode is defective, it can be easily replaced, and there is no need to discard the ball lens and the silicon substrate. For this reason, the manufacturing cost is greatly reduced.

(Embodiment 2) FIG. 4 is a schematic perspective view showing the structure of a laser diode module subassembly according to Embodiment 2 of the present invention. The same reference numerals in the drawings denote the same parts as in the first embodiment, and a description thereof will be omitted.

The structure of the laser diode module subassembly according to the present embodiment will be described. FIG.
2, a metallized region 5 which is a metal thin film layer region is formed on the main surface of the silicon substrate 1 adjacent to the groove 1a in which the ball lens 3 is arranged. The metallized region 5 is made of Au, and is formed on the surface of the silicon substrate 1 by vapor deposition. On this metallized area 5, Fe-
A metal piece 6 made of a Ni—Co alloy is fixed by brazing an Au—Ge alloy.

Further, a leaf spring 4 for pressing the ball lens 3 and fixing it to the silicon substrate 1 is provided on the metal piece 6.
It is mounted by laser welding with a YAG laser (yttrium-aluminum-garnet laser). Here, YAG laser welding is used as welding.
This is because a predetermined portion of the metal piece 6 can be locally heated,
This makes it possible to prevent the silicon substrate 1 from cracking due to a rise in temperature. The leaf spring 4 is made of a thin metal plate having appropriate elasticity, and the ball lens 3 is fixed in the groove 1 a provided in the silicon substrate 1 by the leaf spring 4.

In this configuration, unlike the first embodiment, a leaf spring is mounted on the main surface of the silicon substrate. Since it is not easy to directly attach a leaf spring made of metal on a silicon substrate, a metallized region is provided on the silicon substrate, and the leaf spring is mounted thereon via a metal piece. With this configuration, it is possible to use a leaf spring having a smaller size and a simpler shape than the leaf spring according to the first embodiment, and cost can be reduced. Furthermore, since the leaf spring and the silicon substrate are firmly fixed,
There is no displacement of the ball lens.

(Embodiment 3) FIG. 5 is a schematic perspective view showing the structure of a laser diode module subassembly according to Embodiment 3 of the present invention. The same reference numerals in the drawings denote the same parts as in the second embodiment, and a description thereof will be omitted.

The structure of the laser diode module subassembly according to the present embodiment will be described. FIG.
As shown in FIG. 1, a groove 1a is formed on the main surface of the silicon substrate 1, and a condenser lens 3 and an optical isolator 10 as a backward light attenuating means are arranged in the groove 1a. The condensing lens 3 and the optical isolator 10 are arranged side by side so as to be located on the optical path of light emitted from the laser diode 2 mounted on the main surface of the silicon substrate 1. From the viewpoint, the ball lens, the optical isolator, and the ball lens are arranged in this order. Here, the optical isolator 10 transmits the light emitted from the laser diode 2 to the outside without loss.
The reflected light traveling backward on the same path has a function of attenuating.

A metallized area 5 is formed on the main surface of the silicon substrate 1 adjacent to the groove 1a. On this metallized area 5, a metal piece 6 is brazed,
Further, on the metal piece 6, a plurality of leaf springs 4
Mounted by laser welding. The plurality of leaf springs 4 are connected to the ball lens 3 and the optical isolator 10 described above.
These are brought into contact with and pressed on the silicon substrate 1.
It is fixed to.

According to this structure, not only the ball lens but also other optical components can be easily fixed to the silicon substrate by the leaf spring. The above-mentioned optical isolator is generally larger than other optical components, and it is not easy to fix the optical isolator to a silicon substrate. However, by applying the fixing structure using a leaf spring according to the present invention, it is possible to fix the plate at a predetermined position with high accuracy. Further, since all the optical components can be mounted at room temperature, the mounting strength of the optical component previously mounted is not reduced, and the axial displacement does not occur.

In the above embodiment of the present invention, the shape of a leaf spring for fixing an optical component such as a ball lens on a silicon substrate may be a shape that is extrapolated to the silicon substrate or a metal piece mounted on the silicon substrate. Although described by exemplifying what is attached by welding, it is not particularly limited to these,
Any structure may be used as long as the optical component is sandwiched and fixed between the leaf spring and the silicon substrate.

In the above embodiment of the present invention, a silicon substrate is exemplified as a submount substrate. However, any substrate may be used as long as circuit wiring is patterned on the surface or inside. Good.

Further, in the above embodiment of the present invention, a thin film layer made of Au is exemplified as the metallized region, an Fe—Ni—Co alloy is used as the metal piece, and an Au—Ge alloy is used as the brazing material.
Although an alloy has been described as an example, the present invention is not particularly limited thereto, and may be any as long as it has the same effect.

Therefore, each of the above-described embodiments disclosed this time is an example in all respects, and is not restrictive. The technical scope of the present invention is defined by the appended claims, and includes all modifications within the meaning and scope equivalent to the description of the appended claims.

[0043]

According to the semiconductor light emitting element module subassembly according to the present invention, the semiconductor light emitting element and the optical components such as the condenser lens can be easily and accurately mounted on the submount substrate. In addition, manufacturing costs are reduced. Further, since the optical components can be mounted at room temperature, the yield can be improved, and a highly reliable semiconductor light emitting element module subassembly can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing a structure of a semiconductor light emitting element module subassembly according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of the semiconductor light-emitting element module subassembly according to the first embodiment of the present invention, taken along the line AA ′ in FIG.

FIG. 3 is a schematic perspective view showing a shape of a leaf spring used in the semiconductor light emitting element module subassembly according to the first embodiment of the present invention.

FIG. 4 is a schematic perspective view showing a structure of a semiconductor light emitting element module subassembly according to a second embodiment of the present invention.

FIG. 5 is a schematic perspective view showing a structure of a semiconductor light emitting element module subassembly according to a third embodiment of the present invention.

FIG. 6 is a schematic sectional view showing the structure of a conventional semiconductor light emitting element module.

FIG. 7 is a schematic perspective view showing the structure of a conventional semiconductor light emitting element module subassembly.

8 is a cross-sectional view of the conventional semiconductor light emitting element module subassembly taken along the line BB 'in FIG.

[Explanation of symbols]

1 silicon substrate, 1a groove, 2 laser diode,
3 ball lens, 4 leaf spring, 4a locking piece, 5 metallized area, 6 metal piece, 7 welding nugget, 8 solder, 9 aluminum thin film layer, 10 optical isolator.

Claims (7)

[Claims] A submount substrate having a main surface including a semiconductor light emitting element and a condenser lens positioned on an optical path of light emitted by the semiconductor light emitting element; and a submount mounted on the submount substrate. A semiconductor light-emitting element module sub-assembly, comprising: a fixing member that sandwiches the condenser lens between the substrate and a main surface of the substrate. 2. The fixing member according to claim 1, wherein the fixing member includes an elastic portion, and the elastic portion exerts an elastic force to sandwich the condenser lens between the fixing member and the main surface of the submount substrate. Semiconductor light emitting element module subassembly. 3. The semiconductor light-emitting element module sub-assembly further includes: a backward light attenuating means positioned on the optical path for suppressing transmission of light traveling backward on the optical path; and 3. The semiconductor light emitting element module subassembly according to claim 1, further comprising: an elastic member that sandwiches the backward light attenuating means between the submount substrate and the main surface of the submount substrate. 4. The fixing member has a band shape, and includes a locking piece having both ends folded back, and the locking piece is engaged with a peripheral portion of a main surface opposite to the main surface of the submount substrate. 2. The submount substrate is attached to the submount substrate by joining.
4. The semiconductor light-emitting element module subassembly according to any one of items 1 to 3, 5. The fixing member is made of metal, the submount substrate has a metal thin film layer region on a main surface thereof, and the fixing member is attached to a metal piece placed on the metal thin film layer region. The semiconductor light-emitting element module subassembly according to any one of claims 1 to 3. 6. The semiconductor light emitting element module subassembly according to claim 5, wherein the fixing member is attached to the metal piece by welding. 7. The semiconductor light emitting device module subassembly according to claim 1, wherein said semiconductor light emitting device is a laser diode.