JP2007019087A - Semiconductor laser device and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor laser device capable of reducing the distortion of a laser chip and a manufacturing method for the semiconductor laser device. <P>SOLUTION: The semiconductor laser device has a sub-mount and the laser chip joined with the sub-mount. The sub-mount is extended substantially in the vertical direction to the resonator direction of the laser chip, and has a trench dividing a joint surface with the laser chip. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a semiconductor laser device capable of reducing distortion of a semiconductor laser chip (hereinafter referred to as “laser chip”) and a method for manufacturing the same. The present invention is particularly suitably applied to a semiconductor laser device having a laser chip with a long resonator length and a method for manufacturing the same.

As shown in Patent Document 1, a conventional semiconductor laser device includes a fixing member, a submount bonded to the fixing member, and a laser chip bonded to the submount. The laser chip and the submount are joined by melting a silver material provided between them. At this time, the laser chip and the submount are also heated. If the linear expansion coefficients of the laser chip and the submount are different, the laser chip may be distorted during cooling, and the characteristics of the laser chip may deteriorate. Patent Document 1 discloses a technique in which a submount is configured using two materials having different linear expansion coefficients in order to reduce the difference in linear expansion coefficient between the laser chip and the submount.
Japanese Utility Model Publication No. 2-102756

  However, since the submount according to the technique of Patent Document 1 is difficult to manufacture, a method of reducing the distortion of the laser chip by another method is desired.

  The present invention has been made in view of such circumstances, and provides a semiconductor laser device capable of reducing distortion of a laser chip and a manufacturing method thereof.

Means for Solving the Problems and Effects of the Invention

The semiconductor laser device of the present invention includes a submount and a laser chip bonded to the submount, and the submount extends in a direction substantially perpendicular to the resonator direction of the laser chip and is connected to the laser chip. A groove for dividing the joining surface is provided.
According to the present invention, the submount includes the groove, and the distortion of the laser chip is reduced by changing the width of the groove.

The groove preferably penetrates the submount and divides the submount into first and second members. In this case, the width of the groove can be changed relatively easily. Moreover, it is preferable that the 1st and 2nd member is partially connected with the connection material whose Young's modulus is smaller than a submount. In this case, since the first and second members are connected to each other, handling thereof is easy. Further, since the first and second members are connected by a relatively flexible material, the groove width is easily changed, and the effect of reducing distortion of the laser chip is great.
The groove may be non-penetrating through the submount. Since the submount is not separated into the first and second members, it is easy to handle. In addition, this submount can be manufactured by forming a groove in a conventional submount, so that it is easy to manufacture.
The submount is preferably made of SiC. Since SiC has a relatively high thermal conductivity, the use of the groove makes it possible to obtain a semiconductor laser device having excellent performance with high heat dissipation and low distortion of the laser chip.

  In the method of manufacturing a semiconductor laser device according to the present invention, the first and second members to be the submount are connected with a low boiling point material to form a connected body, and the resonator direction is at a temperature equal to or higher than the boiling point of the low boiling point material. Includes a step of bonding the laser chip to the submount so that the connection portion is substantially perpendicular to the connection portion of the connection body and the connection portion divides the bonding surface. According to this method, the distance between the first and second members, that is, the width of the groove formed between the first and second members can be easily adjusted by adjusting the thickness of the low boiling point material. .

According to another aspect of the present invention, there is provided a method of manufacturing a semiconductor laser device, wherein a laser chip is provided on a submount having a groove so that a resonator direction is substantially perpendicular to the groove and the groove divides a bonding surface. A step of joining to the submount. A semiconductor laser device in which the distortion of the laser chip is reduced is obtained.
The groove is preferably formed by a step of partially connecting the first and second members to be the submount with a connecting material having a Young's modulus smaller than that of the submount. In this case, since the first and second members are connected to each other, handling thereof is easy.
The groove is preferably formed by a half die. In this case, since the groove can be formed when the submount wafer is separated into individual submounts by dicing, the groove can be easily formed.
The groove may be formed by etching. Also in this case, the groove can be easily formed.
The laser chip is preferably joined to the submount via a brazing material disposed in a predetermined region excluding the groove vicinity region. In this case, the brazing material is prevented from flowing into the groove and filling the groove.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The drawings are used for convenience of explanation, and the scope of the present invention is not limited to the embodiments shown in the drawings.

1. First Embodiment FIG. 1 is a cross-sectional view showing a semiconductor laser device according to a first embodiment of the present invention. As shown in FIG. 1, the semiconductor laser device of the present embodiment includes a submount 3 and a laser chip 5 bonded to the submount 3, and the submount 3 divides a bonding surface with the laser chip 5. A groove 7 is provided. The groove 7 extends in a direction substantially perpendicular to the resonator direction (indicated by arrow A) of the laser chip 5 (direction perpendicular to the paper surface). The groove 7 faces the laser chip 5, penetrates the submount 3, and divides the submount 3 into first and second members 3a and 3b. The joint surface between the submount 3 and the laser chip 5 is divided into a joint surface between the first member 3 a and the laser chip 5 and a joint surface between the second member 3 b and the laser chip 5.
The position of the groove 7 is preferably near the center of the bonding surface in the resonator direction. The width of the groove 7 is preferably 1 μm or more, more preferably 2 μm or more.
The submount 3 is joined to the stem 11 via the first brazing material 9. The laser chip 5 is joined to the submount 3 via the second brazing material 10. The material of the first brazing material 9 and the second brazing material 10 is not particularly limited. For example, a silver paste, In, or the like can be used for the first brazing material 9, and AuSn solder can be used for the second brazing material 10. SnAgCu or the like can be used. When the laser chip 5 is joined to the submount 3 and then the submount 3 is joined to the stem 11, it is preferable to use the second brazing material 10 having a higher melting point than the first brazing material 9. Note that a metal film such as an AuZn film is usually formed on the surface of the laser chip 5 facing the submount 3, and a Ti / Au multilayer film or the like is usually formed on both main surfaces of the submount 3. A metal film is formed. The stem 11 is usually made of a metal such as Cu or Fe. Therefore, metals are usually joined by the first brazing material 9 and the second brazing material 10.

The submount 3 is preferably formed of a material having a high thermal conductivity and a linear expansion coefficient close to that of the laser chip 5, for example, AlN, SiC, Si or the like. Table 1 shows the linear expansion coefficient and thermal conductivity of these materials.

  According to Table 1, it can be seen that SiC is preferable from the viewpoint of thermal conductivity.

In the case of an AlGaAs type laser, the laser chip 5 is usually formed by forming various semiconductor layers on a GaAs substrate. The linear expansion coefficient of GaAs is 6.8 × 10 ⁻⁶ K ⁻¹ . When this value is compared with the value in Table 1, it can be seen that when the laser chip 5 is formed using a GaAs substrate, AlN is preferable as the material of the submount 3.

  Even when AlN is used as the material of the submount 3, the linear expansion coefficient of the laser chip 5 is larger. Therefore, the laser chip 5 is joined to the submount 3 by melting the second brazing material 10 and solidifying by subsequent cooling, but the laser chip 5 contracts more greatly than the submount 3 during cooling. However, since the positional relationship between the laser chip 5 and the submount 3 is fixed after the second brazing material 10 is solidified, the laser chip 5 cannot be reduced to its original size, and the laser chip 5 As a result, the laser chip 5 is distorted. This distortion becomes larger as the resonator length of the laser chip 5 becomes longer (for example, 1.5 mm or more), and the submount 3 is formed using SiC whose linear expansion coefficient is smaller than AlN with emphasis on thermal conductivity. The case also gets bigger.

  In the semiconductor laser device of the present embodiment, the submount 3 includes a groove 7 that divides the bonding surface with the laser chip 5, and the width of this groove is narrowed so that the laser chip 5 is located in the vicinity of the groove. The pulled state is canceled. Therefore, the distortion of the laser chip 5 is reduced by that amount. Therefore, in the semiconductor laser device of this embodiment, even when a laser chip having a resonator length of 1.5 mm or more is used and a SiC submount is used, the distortion of the laser chip can be made relatively small.

  In the present embodiment, the groove 7 is formed so as to divide the submount 3 into the first and second members 3a and 3b, so that the width thereof is relatively easy to change, and the distortion of the laser chip 5 is reduced. The effect is great.

  The laser chip 5 may be other than that using a GaAs substrate. Further, when the linear expansion coefficient of the laser chip 5 is smaller than that of the submount, the laser chip 5 is compressed by the submount 3 and is opposite to the above case. By increasing the width, the distortion of the laser chip 5 is reduced as described above.

Next, a method for manufacturing the semiconductor laser device of this embodiment will be described.
First, as shown in FIG. 2A, the first and second members 3a and 3b that become the submount 3 are connected by a low boiling point material 13 to form a connected body. Specifically, for example, the low boiling point material 13 is applied to the first member 3a with a thickness of preferably 1 μm or more, more preferably 2 μm or more, and the second member 3b is applied to the first member material via the low boiling point material 13. Connect to 3a. As the low boiling point material 13, a material having a boiling point lower than the bonding temperature of the laser chip 5 and capable of connecting the first and second members 3a and 3b to each other can be used.

  Next, as shown in FIG. 2B, the laser chip 5 is joined to the connector at a temperature equal to or higher than the boiling point of the low boiling point material 13. The laser chip 5 is preferably bonded so that the resonator direction is substantially perpendicular to the connecting portion. The laser chip 5 is bonded using the second brazing material 10. Since the laser chip 5 is bonded at a temperature equal to or higher than the boiling point of the low boiling point material 13, the low boiling point material 13 is vaporized at the time of bonding, and the submount 3 having the grooves 7 is formed. The second brazing material 10 is previously disposed on the coupling body or the laser chip 5 by coating or vapor deposition.

  Next, the submount 3 is joined to the stem 11 with the first brazing material 9 to obtain the structure shown in FIG. 1, and the manufacture of the semiconductor laser device of this embodiment is completed. The first brazing material 9 is previously disposed on the submount 3 or the stem 11 by coating or vapor deposition.

  The semiconductor laser device of this embodiment can be manufactured by another method. For example, the laser chip 5 may be bonded to the submount 3 after the coupling body is bonded to the stem 11. At this time, the submount 3 having the grooves 7 may be formed by vaporizing the low boiling point material 13 by bonding to the stem 11 at a temperature equal to or higher than the boiling point of the low boiling point material 13.

  Further, after forming the submount 3 having the groove 7 by joining the first and second members 3a and 3b to the stem 11 at a predetermined interval without forming a coupling body, the laser chip 5 is formed. May be joined to the submount 3. After forming the submount 3 having the grooves 7 by joining the laser chip 5 to the first and second members 3a and 3b with the first and second members 3a and 3b spaced apart from each other, The submount 3 may be joined to the stem 11. The brazing material used for joining the members can be appropriately selected from those other than those described above. In particular, when the submount 3 is first joined to the stem 11, it is preferable to use the first brazing material 9 having a higher melting point than the second brazing material 10.

2. Second Embodiment FIG. 3 is a cross-sectional view showing a semiconductor laser device according to a second embodiment of the present invention. As shown in FIG. 3, in the semiconductor laser device of this embodiment, the first and second members 3 a and 3 b that become the submount 3 are partially connected by a connecting material 15 having a Young's modulus smaller than that of the submount 3. In this respect, the semiconductor laser device of the first embodiment is different. The portion not connected by the connecting material 15 becomes the groove 7. Accordingly, the first and second members 3a and 3b are connected so that the groove 7 is formed. The position of the groove 7 is preferably near the center of the bonding surface in the resonator direction. The width of the groove 7 is preferably 1 μm or more, more preferably 2 μm or more. The depth of the groove 7 is preferably about 1/5 to 1/2 of the thickness of the submount 3.
As the connection material 15, a material capable of connecting the first and second members 3 a and 3 b to each other and having a Young's modulus smaller than that of the submount 3 can be used.

  According to this embodiment, since the 1st and 2nd members 3a and 3b are mutually connected, the handling is easy. Further, since the first and second members 3a and 3b are connected by a relatively flexible material, the width of the groove 7 is easily changed, and the effect of reducing distortion of the laser chip 5 is relatively large.

Next, a method for manufacturing the semiconductor laser device of this embodiment will be described.
First, as shown in FIG. 4A, the first and second members 3a and 3b to be the submount 3 are partially connected with a connecting material 15 having a low Young's modulus, and the submount 3 having the grooves 7 is produced. To do. Specifically, for example, the connecting material 15 is applied to the first member 3a with a thickness of preferably 1 μm or more, more preferably 2 μm or more, and the second member 3b is connected to the first member 3a via the connecting material 15. Let

  Next, as shown in FIG. 4B, the laser chip 5 is bonded to the submount 3 so that the groove 7 divides the bonding surface. The laser chip 5 is bonded so that the resonator direction is substantially perpendicular to the groove 7. The laser chip 5 is bonded using the second brazing material 10. The second brazing material 10 is previously disposed on the submount 3 or the laser chip 5 by coating or vapor deposition.

  Next, the submount 3 is joined to the stem 11 with the first brazing material 9 to obtain the structure shown in FIG. 3, and the manufacture of the semiconductor laser device of this embodiment is completed. The first brazing material 9 is previously disposed on the submount 3 or the stem 11 by coating or vapor deposition.

The semiconductor laser device of this embodiment can be manufactured by another method. For example, the laser chip 5 may be bonded to the submount 3 after the submount 3 having the grooves 7 is bonded to the stem 11.
The description of the first embodiment also applies to the present embodiment unless it is contrary to the spirit of the first embodiment.

3. Third Embodiment FIG. 5 is a cross-sectional view showing a semiconductor laser device according to a third embodiment of the present invention. As shown in FIG. 5, the semiconductor laser device of this embodiment is different from the semiconductor laser device of the second embodiment in that the submount 3 is made of a single member. The position of the groove 7 is preferably near the center of the bonding surface in the resonator direction. The width of the groove 7 is preferably 1 μm or more, more preferably 2 μm or more. The depth of the groove 7 is preferably about 1/3 to 2/3 of the thickness of the submount 3.

  In the present embodiment, since the submount 3 is made of a single member, it is easy to handle, and the submount 3 can be manufactured by forming a groove in a conventional submount, and thus can be manufactured easily.

Next, a method for manufacturing the semiconductor laser device of this embodiment will be described.
First, as shown in FIG. 6A, the groove 7 is formed in the submount 3 by a half die. “Half die” means that a dicing blade is used to form a groove so as not to separate the submount into the first and second members. Moreover, you may form the groove | channel 7 by an etching instead of a half die. Etching may be dry etching or wet etching. Etching can be performed using a resist mask formed by photolithography.

  Next, as shown in FIG. 6B, the laser chip 5 is bonded to the submount 3 so that the groove 7 divides the bonding surface. The laser chip 5 is bonded so that the resonator direction is substantially perpendicular to the groove 7. The laser chip 5 is bonded using the second brazing material 10. The second brazing material 10 is previously disposed on the submount 3 or the laser chip 5 by coating or vapor deposition. As shown in FIG. 6 (b), the second brazing filler metal 10 has a predetermined region excluding the region near the groove 7 in order to avoid the second brazing filler metal 10 from flowing into the groove 7 and filling the groove 7 when melted. It is preferable to arrange in.

  Next, the submount 3 is joined to the stem 11 with the first brazing material 9 to obtain the structure shown in FIG. 5, and the manufacture of the semiconductor laser device of this embodiment is completed. The first brazing material 9 is previously disposed on the submount 3 or the stem 11 by coating or vapor deposition.

The semiconductor laser device of this embodiment can be manufactured by another method. For example, the laser chip 5 may be bonded to the submount 3 after the submount 3 having the grooves 7 is bonded to the stem 11.
The description of the second embodiment applies to this embodiment as long as it does not contradict its purpose.

4). Fourth Embodiment FIG. 7 is a cross-sectional view showing a semiconductor laser device according to a fourth embodiment of the present invention. As shown in FIG. 7, the semiconductor laser device of this embodiment is different from the semiconductor laser device of the third embodiment in that a plurality of grooves 7 are provided. The number of grooves 7 is preferably 2-5. The grooves 7 are preferably arranged evenly in the resonator direction. The width of each groove 7 is preferably 1 μm or more, and more preferably 2 μm or more. The depth of each groove 7 is preferably about 1/3 to 2/3 of the thickness of the submount 3. The width or depth of the grooves may be the same or different from each other.
In the present embodiment, since the plurality of grooves 7 are formed in the submount 3, the effect of reducing distortion of the laser chip is great.
The semiconductor laser device of this embodiment can be manufactured by the same method as that of the third embodiment except that a plurality of grooves 7 are formed.
The description of the third embodiment also applies to the present embodiment unless it is contrary to the spirit thereof.

It is sectional drawing which shows the structure of the semiconductor device of 1st Embodiment of this invention. It is sectional drawing which shows the manufacturing process of the semiconductor device of 1st Embodiment of this invention. It is sectional drawing which shows the structure of the semiconductor device of 2nd Embodiment of this invention. It is sectional drawing which shows the manufacturing process of the semiconductor device of 2nd Embodiment of this invention. It is sectional drawing which shows the structure of the semiconductor device of 3rd Embodiment of this invention. It is sectional drawing which shows the manufacturing process of the semiconductor device of 3rd Embodiment of this invention. It is sectional drawing which shows the structure of the semiconductor device of 4th Embodiment of this invention.

Explanation of symbols

3: Submount 3a, 3b: First and second members of submount 5: Laser chip 7: Groove 9: First brazing material 10: Second brazing material 11: Stem 13: Low boiling point material 15: Connecting material

Claims (11)

A submount and a laser chip bonded to the submount,
The submount includes a groove that extends in a direction substantially perpendicular to the cavity direction of the laser chip and divides a bonding surface with the laser chip. The apparatus of claim 1, wherein the groove penetrates the submount and divides the submount into first and second members. The apparatus according to claim 2, wherein the first and second members are partially connected with a connecting material having a Young's modulus smaller than that of the submount. The apparatus of claim 1, wherein the groove is non-penetrating through the submount. The apparatus of claim 1, wherein the submount comprises SiC. The first and second members to be the submount are connected with a low boiling point material to form a connected body,
The laser chip is bonded to the submount so that the resonator direction is substantially perpendicular to the connecting portion of the connecting body and the connecting portion divides the bonding surface at a temperature equal to or higher than the boiling point of the low boiling point material. A method of manufacturing a semiconductor laser device comprising the steps. A method of manufacturing a semiconductor laser device, comprising: a step of bonding a laser chip to a submount so that a resonator direction is substantially perpendicular to the groove and the groove divides a bonding surface on a submount having a groove. The method according to claim 7, wherein the groove is formed by partially connecting the first and second members to be a submount with a connecting material having a Young's modulus smaller than that of the submount. The method of claim 7, wherein the groove is formed by a half die. The method of claim 7, wherein the groove is formed by etching. The method according to claim 7, wherein the laser chip is bonded to the submount via a brazing material disposed in a predetermined area excluding the groove vicinity area.

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