JPH07193315A - Semiconductor laser system and manufacture thereof - Google Patents

Abstract

PURPOSE:To increase the radiating capacity for enhancing the reliability and performance by suppressing the chip cracking caused by thermal stress. CONSTITUTION:Irregularities 5 are formed on the semiconductor substrate 6 side of a semiconductor element 1 so as to relieve the thermal stress imposed by the difference in the thermal expansion coefficient between the semiconductor element 1 and a heat sink 4. Accordingly, the chip cracking caused by thermal stress can be avoided while increasing the radialting capacity thereby enabling the saturated optical output to be extended.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser device having a heat sink.

[0002]

2. Description of the Related Art Currently, in the fields of optical communication and optical measurement,
Along with long-distance operation and higher performance, higher output of semiconductor laser devices is required. In order to meet the demand from such a system, a semiconductor laser device has been made to have a long resonator, and a semiconductor laser having a resonator length of more than 900 μm has been developed.

As shown in FIG. 7, a general semiconductor laser device has a structure in which a semiconductor laser element 1 is fused on a heat sink 4 of an integrated type via a solder 3. For a semiconductor laser device with a cavity length of about 300 μm,
Although BN and synthetic diamond having high heat dissipation are used as the heat sink material, since the bonding area between the semiconductor element 1 and the heat sink 4 is large in the high output laser device, the difference in thermal expansion coefficient between the semiconductor element 1 and the heat sink 4 is large. It cannot be ignored. Therefore, in a high-power laser device, deterioration of the semiconductor element due to such a difference in thermal expansion coefficient becomes a problem. In order to avoid this in the conventional high-power laser device,
A heat sink material having a thermal expansion coefficient similar to that of a semiconductor such as Inp, for example, AlN is used. However, in this case, the heat dissipation of the heat sink is less than that of BN or synthetic diamond.
There was a drawback that it became about / 10.

On the other hand, in a semiconductor device such as an integrated circuit, unevenness is formed on the front and back surfaces of the semiconductor element in order to prevent deterioration of the semiconductor element caused by a difference in coefficient of thermal expansion between the semiconductor element and another material in contact with the semiconductor element. It is already known that a groove is formed on the front and back surfaces of a heat sink, and a heat sink is separately formed. As the first example, FIG.
There are those shown in (a) and (b), which are formed by forming the unevenness 5 on the surface of the semiconductor element 11 in the resin-sealed semiconductor device so that the semiconductor element 11 and the resin (resin) are formed.
It is intended to prevent the peeling from 14 (JP-A-62-62
-252156). As a second example, as shown in FIG. 9, in a semiconductor device in which a plated heat sink (PHS) 16 is formed on the back surface of the semiconductor element 11, the PHS 16 is divided to prevent deformation of the semiconductor element 11. (Japanese Patent Laid-Open No. 63-131)
555 publication). As a third example, as shown in FIG. 10, in a semiconductor device in which the hermetically sealed package 17 and the heat sink 4 are bonded by the solder 3 of low melting point glass, the bonding surface of the heat sink 4 is divided. There is one in which thermal stress is reduced to a small extent to prevent the occurrence of cracks (Japanese Patent Laid-Open No. 3-101257). Further, as a fourth example, as shown in FIG. 11, in a semiconductor device having a structure for sealing the semiconductor element 11, the unevenness 5 is formed on the front and back surfaces of the members other than the semiconductor element 11, and the solder 3 used is meshed. There is one in which the thermal stress is dispersed by forming the shape (Japanese Patent Laid-Open No. 4-320873).

These prior arts have taken countermeasures against thermal stress generated when a semiconductor element is fused to a heat sink or other member. Regarding the heat dissipation during operation which is particularly required in the semiconductor laser device. Since it is not taken into consideration, a sufficient effect cannot be obtained even if it is directly applied to a high-power semiconductor laser device. Further, in a high-power semiconductor laser device, the amount of heat generated from the semiconductor laser element during operation is 10 times or more compared to the conventional one, so that the semiconductor laser device to which the above-described conventional technique is applied is saturated by such heat generation. The problem of reduced light output remains.

[0006]

As described above, in the conventional semiconductor laser device, when a heat sink material having high thermal conductivity (good heat dissipation) such as BN or synthetic diamond is used, a chip caused by thermal stress is generated. There is a problem in that the reliability of the semiconductor laser is deteriorated due to cracks, and there is a problem in heat dissipation of the semiconductor laser element when a heat sink material having a small difference in thermal expansion coefficient such as AlN is used.

Further, when a conventional technique for dispersing thermal stress in a semiconductor device such as an integrated circuit is also applied to a semiconductor laser device, there is a problem in heat dissipation and it is insufficient for heat generation of a semiconductor laser element.

The present invention has been made under such a background, and it is possible to obtain high reliability by suppressing the generation of cracks due to thermal stress in the semiconductor element and ensuring sufficient heat dissipation. An object of the present invention is to provide a semiconductor laser device having both high performance.

[0009]

According to a first aspect of the present invention, in a semiconductor laser device, a semiconductor element having an active layer formed on one surface of a plate-shaped semiconductor substrate is attached to a heat sink via a solder. In the semiconductor laser device, unevenness is formed on the other surface of the semiconductor substrate, and the one surface is in contact with the solder.

A second aspect of the present invention is a semiconductor laser device in which a semiconductor element having an active layer formed on one surface of a plate-shaped semiconductor substrate is attached to a heat sink via a solder. An unevenness is formed on the other surface of the semiconductor substrate, and the top of the unevenness is in contact with the solder.

A third aspect of the present invention is a method of manufacturing a semiconductor laser device, wherein a large number of irregularities are formed by photo-etching on the other surface of a semiconductor element having an active layer formed on one surface of a plate-shaped semiconductor substrate. It is characterized by including a step of forming.

A fourth aspect of the present invention is a semiconductor laser device in which a semiconductor element having an active layer formed on one surface of a plate-shaped semiconductor substrate is attached to a heat sink via a solder. The semiconductor device is characterized in that the heat sink is divided into a plurality of blocks to an extent sufficient to alleviate the mechanical stress applied between the semiconductor device and the heat sink due to the temperature rise of the semiconductor device due to laser emission.

[0013]

The plurality of grooves provided in the semiconductor element increases the surface area, promotes heat dissipation during operation as a laser element, and relaxes the thermal stress generated between the semiconductor element and the heat sink.
Prevents chip cracks or chip deformation to improve life. Further, since the temperature of the semiconductor element is kept low by improving the heat dissipation, the saturated light output can be improved.

[0014]

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

(First Embodiment) FIG. 1 is a sectional view showing the structure of the first embodiment of the present invention.

In the first embodiment of the present invention, the semiconductor element 1 is mounted on the integrated heat sink 4 by the AuSn solder 3, for example.

A method of manufacturing the semiconductor device 1 of the first embodiment of the present invention thus constructed will be described with reference to FIG. The active layer 2 and the clad layer 7 are sequentially epitaxially grown on the semiconductor substrate 6 (FIG. 3A), and the photoresist 8 is patterned on the back surface of the device 1 as an etching mask (FIG. 2B). Next, the unevenness 5 having a depth of 50 μm is formed on the semiconductor substrate 6 side by using the dry etching method (the same figure (c)), and the remaining photoresist 8 is removed (the same figure (d)).

When the semiconductor element 1 having the concavities and convexities 5 on the side of the semiconductor substrate 6 thus formed is mounted on the heat sink 4, the thermal stress due to the difference in thermal expansion coefficient from the heat sink 4 is relieved by the concavities and convexities 5. be able to. Further, the heat generated from the semiconductor element 1 can also be diffused into the atmosphere by the unevenness 5, so that the heat dissipation of the semiconductor element 1 is also improved. As a result, generation of chip cracks due to thermal stress is suppressed, and a highly reliable semiconductor device having excellent heat dissipation can be obtained.

(Second Embodiment) FIG. 3 is a sectional view showing the structure of the second embodiment of the present invention.

In the second embodiment of the present invention, the unevenness 5 side in the first embodiment is fused to the heat sink 4 side. In the case of the second embodiment, the thermal stress generated at the joint surface between the semiconductor element 1 and the heat sink 4 is dispersed along the unevenness 5. Therefore,
Also in this case, similarly to the first embodiment, the generation of chip cracks due to thermal stress can be suppressed and sufficient heat dissipation can be provided. (Third Embodiment) FIG. 4 is a sectional view showing the structure of the third embodiment of the present invention. In the third embodiment of the present invention, the semiconductor laser device 1 is mounted on the integrated heat sink 4 via the solder 3, for example, AuSn, and at least one hole 9 is formed on the semiconductor substrate 6 side of the semiconductor device 1. It is formed. In this example, 300 μm (W) × 900 μm (L) × 100
On the semiconductor substrate 6 side of the semiconductor laser device 1 of μm (T),
200μm (W) × 800μ by dry etching method
A hole 9 having a rectangular shape of m (L) × 50 μm (T) is formed. As for the third embodiment, as in the first embodiment,
The holes 9 relax thermal stress and efficiently dissipate generated heat, thereby improving reliability and performance.

(Fourth Embodiment) FIGS. 5A and 5B are a sectional view and a plan view showing the structure of a fourth embodiment of the present invention. The fourth embodiment of the present invention is a split type heat sink 10.
The semiconductor element 1 is mounted on the upper surface of the AuSn solder 3 via, for example, 750 μm (W) × 1200 μ.
75 m (L) x 300 μm (T) BN heat sink
It is divided into four into a size of 0 μm (W) × 300 μm (L) × 300 μm (T). As a result, the thermal stress generated at the joint surface between the semiconductor element 1 and the split heat sink 10 can be dispersed by the split surface, and a heat sink member having a high thermal conductivity (good heat dissipation), such as BN or synthetic diamond, is used. Even in such a case, the generation of chip cracks can be suppressed, and a semiconductor laser device having high reliability and high performance can be obtained.

(Fifth Embodiment) FIG. 6 is a sectional view showing the structure of the fifth embodiment of the present invention. The fifth embodiment of the present invention is constructed by mounting the semiconductor element 1 described in the first embodiment of the present invention on the split heat sink 7 described in the fourth embodiment of the present invention. Also in the case of this example, similarly to the first and fourth embodiments, it is possible to suppress the occurrence of chip cracks due to thermal stress and to provide sufficient heat dissipation.

[0023]

As described above, according to the present invention, the semiconductor is formed by forming unevenness on the semiconductor substrate side of the semiconductor element or on the heat sink side with good heat dissipation, or by separating and arranging the heat sink itself. Thermal stress generated between the semiconductor element and the heat sink can be relaxed by the heat generated during the operation of the laser element that emits laser light. As a result, chip cracks and chip deformation can be suppressed to improve the life, and the improved heat dissipation keeps the temperature of the operating laser element low, thus increasing saturated light output. There is an effect that can be done.

[Brief description of drawings]

FIG. 1 is a sectional view showing the configuration of a first embodiment of the present invention.

2A to 2D are views for explaining a method for manufacturing a semiconductor laser device in the first embodiment of the present invention.

FIG. 3 is a sectional view showing the configuration of a second embodiment of the present invention.

FIG. 4 is a sectional view showing the configuration of a third embodiment of the present invention.

5A and 5B are a sectional view and a plan view showing a configuration of a fourth embodiment of the present invention.

FIG. 6 is a sectional view showing the structure of a fifth embodiment of the present invention.

FIG. 7 is a sectional view showing a configuration of a conventional example.

8A and 8B are a plan view and a cross-sectional view showing a first configuration example of a conventional example of a semiconductor device.

FIG. 9 is a cross-sectional view showing a second configuration example of a conventional example of a semiconductor device.

FIG. 10 is a cross-sectional view showing a third configuration example of a conventional example of a semiconductor device.

FIG. 11 is a cross-sectional view showing a fourth configuration example of a conventional example of a semiconductor device.

[Explanation of symbols]

 1, 11 Semiconductor Element 2 Active Layer 3 Solder 4 Heat Sink 5 Concavo-convex 6 Semiconductor Substrate 7 Clad Layer 8 Photoresist 9 Hole 10 Divided Heat Sink 12 Bonding Pad 13 Wire 14 Resin 15 Tab 16 Plated Heat Sink 17 Airtight Package 18 header

Claims (4)

[Claims] 1. A semiconductor laser device in which a semiconductor element having an active layer formed on one surface of a plate-shaped semiconductor substrate is attached to a heat sink via a solder, and unevenness is formed on the other surface of the semiconductor substrate. And the one surface is in contact with the solder. 2. A semiconductor laser device in which a semiconductor element having an active layer formed close to one surface of a plate-shaped semiconductor substrate is attached to a heat sink via a solder, and unevenness is formed on the other surface of the semiconductor substrate. The semiconductor laser device is characterized in that the tops of the irregularities are in contact with the solder. 3. A method of manufacturing a semiconductor laser device including a step of forming a large number of irregularities by photo-etching on the other surface of a semiconductor element having an active layer formed on one surface of a plate-shaped semiconductor substrate. 4. A semiconductor laser device in which a semiconductor element having an active layer formed on one surface of a plate-shaped semiconductor substrate is attached to a heat sink via a solder, and the temperature of the semiconductor element rises due to laser emission, A semiconductor laser device characterized in that the heat sink is divided into a plurality of blocks to an extent sufficient to relieve the mechanical stress applied between the heat sink and the heat sink.