JP3724834B2 - Manufacturing method of semiconductor laser device - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a method for manufacturing a semiconductor laser device, and more particularly to an assembly method.
[0002]
[Prior art]
In recent years, semiconductor laser devices are required to have high output. As a manufacturing method for obtaining a higher-power semiconductor laser device, J-down assembly or stack assembly is generally employed. In the J-down assembly, the active layer side (junction side) is set to the lower side (down) in order to improve heat release, and the submount is separated by AuSn solder. The stack assembly is a method of stacking semiconductor laser devices in the vertical direction.
FIG. 4-a shows a J-down assembly method. In the figure, 1 is a semiconductor laser chip, 2 is an active layer that emits light, 3 is a submount, 4 is an AuSn solder pellet, and 5 is an Au layer formed on the submount. FIG. 4B shows a problem in the conventional J-down assembly method. In the figure, 6 is the wraparound of AuSn solder. In the case of J-down assembly, since the distance between the active layer 2 and the submount 3 is only a few μm, it is difficult to control the amount of the AuSn solder pellets 4. An assembly failure occurs that covers and blocks light.
[0003]
FIG. 5 shows a conventional stack assembling method. In the figure, reference numeral 7 denotes AuSn solder, and the semiconductor laser chip 1 and the submount 3 are separated by AuSn solder 7. However, as in the case of J-down assembly, when the amount of AuSn solder is large, the AuSn solder protrudes. In addition, an angle shift between the semiconductor laser chips occurs.
There is also a method in which a solder material is formed at the manufacturing stage of the semiconductor laser device and assembled. FIG. 6 shows an embodiment disclosed in Japanese Patent Laid-Open No. 6-7628. In FIG. 6, 7 is AuSn solder formed at the manufacturing stage of the semiconductor laser device, and 8 is formed at the manufacturing stage of the semiconductor laser device. The Sn layer 9 is an Sn layer formed on the submount. In this method, it is difficult to control the composition of the AuSn alloy layer, and the AuSn alloy layer does not melt at the time of assembly, which may result in an assembly failure. Further, since the semiconductor laser device is cut out by cleavage, a defect at the time of cleavage may occur due to the AuSn solder 7 and the Sn layer 8 formed in micron order.
[0004]
[Problems to be solved by the invention]
As described above, in the conventional method of assembling a semiconductor laser device, it is difficult to control the amount of AuSn solder, and there is a problem in that the AuSn solder protrudes and the angle between semiconductor laser chips during stack assembly occurs. . Further, in the method of forming and assembling the solder material at the manufacturing stage of the semiconductor laser device, there is a problem that it is difficult to control the composition ratio of the AuSn alloy layer and that a defect occurs at the time of cleavage.
[0005]
The present invention has been made to solve the above-described problems. It enables the control of the amount of AuSn solder, prevents the AuSn solder from sticking out during assembly, the occurrence of angular deviation, and the like. It is an object of the present invention to provide a method for manufacturing a semiconductor laser device that does not cause open defects.
[0006]
[Means for Solving the Problems]
A method of manufacturing a semiconductor laser device according to the present invention includes a step of forming a resist pattern at a cleavage site on a laser electrode and selectively plating an Sn layer in a region excluding the cleavage site, and an upper layer of the Sn layer. Forming an Au layer by electroless substitution plating, and further forming an Au layer by electrolytic plating on the upper layer of the Au layer; and the semiconductor laser on the surface of the submount on which the Au layer is formed. A step of stacking a plurality of chips with the active layer side up, and melting an Au layer and an Sn layer interposed between the submount and the semiconductor laser chip, and between the semiconductor laser chips, thereby forming an AuSn alloy layer. Forming a stack.
In addition, a step of selectively plating the Sn layer on the active layer side laser electrode, and after forming an Au layer on the upper layer of the Sn layer by electroless displacement plating, an electrolytic plating is applied on the upper layer of the Au layer. Further, a step of forming an Au layer, a step of stacking the active layer side of the semiconductor laser chip on the surface of the submount on which the Au layer is formed, and an Au interposed between the submount and the semiconductor laser chip J-down assembly is performed with a step of forming an AuSn alloy layer by melting the layer and the Sn layer.
In addition, an Au layer is selectively plated under the Sn layer .
[0007]
[Action]
In the manufacturing method of the semiconductor laser device of this invention, since an Au layer in an electroless substituted plating layer of the hands selectively formed Sn layer plating in a region excluding a cleaved portion, the urging of the Sn layer A strong adherence and an easy-to-peel Au film can be formed. Further, by forming an Au layer by electrolytic plating, oxidation of the Sn layer and etching with a resist stripping solution can be prevented, so that no cleavage failure occurs. The composition of the AuSn alloy is stabilized, and stack assembly and J-down assembly can be performed with high yield.
Further, by selectively plating the Au layer below the Sn layer, the Sn layer is sandwiched between the Au layers, and alloying can be performed more reliably.
[0008]
【Example】
Reference Example 1
A reference example of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a flow up to stack assembly in a semiconductor laser device manufacturing method which is a reference example of the present invention. In the figure, 10 is a laser electrode, 11 is active layer side selective Au plating, 12 is a resist pattern for selective plating, 13 is selective Au plating, 14 is selective Sn plating, 15 is an arrow indicating the cleavage direction, and 16 is on the submount. Au layer. The same parts and the same materials as those in the conventional example are denoted by the same reference numerals, and the description thereof is omitted.
[0009]
The assembly method will be described with reference to the drawings. First, the laser electrode 10 is formed on the semiconductor laser chip 1 before cleaving in which the selective Au plating 11 is formed with a thickness of 2 μm on the surface on the active layer side (FIG. 1A). Next, a resist pattern 12 for selective plating is formed to prevent the formation of plating on the cleavage portion (FIG. 1-b). Then, a selective Au plating 13 is formed with a thickness of 1 μm (FIG. 1-c), and a selective Sn plating 14 is formed thereon with a thickness of 2 μm (FIG. 1-d). Thereafter, the resist pattern 12 for selective plating is removed (FIG. 1-e), and separated into individual semiconductor laser chips 1 from the direction of the arrow 15 by cleavage (FIG. 1-f). Further, a stack of two semiconductor laser chips 1 (FIG. 1-g) is placed on the submount 3 on which the Au layer 16 having a thickness of 2 μm is formed, and is placed in an atmosphere of 340 ° C. for a predetermined time. When processed, Au and Sn are alloyed to form Au: Sn = 8: 2 wt% AuSn solder 7 (FIG. 1-h).
[0010]
According to this reference example , since Au and Sn are each formed as a single layer, by controlling the thickness of each, an arbitrary composition of AuSn solder can be obtained and alloyed reliably. Further, since the AuSn solder amount can be easily controlled by changing the plating film thickness of each of the Au layer and the Sn layer and the area of the resist pattern, it is possible to prevent the AuSn solder from protruding and the angular deviation during stack assembly. Further, selective plating is performed while avoiding the cleavage portion to form the AuSn solder material, so that it does not cause cleavage defects. From the above, according to the manufacturing method of this reference example , the stack assembly of the semiconductor laser device can be easily performed, and the yield is improved.
[0011]
Example 1 .
In Reference Example 1, since the selective Sn plating 14 is on the outermost surface of the semiconductor laser chip, it is known that Sn is etched by about 0.3 μm by the stripping solution for removing the selective plating resist pattern 12. In addition, since Sn is easily oxidized, an Au layer for protecting Sn is formed on the Sn plating 14 in this embodiment.
FIG. 2 is a diagram showing a flow of forming an Au layer on the selective Sn plating 14 formed in Reference Example 1. In the figure, 17 is electroless substitutional Au plating.
[0012]
A method of manufacturing the semiconductor laser device according to this embodiment will be described with reference to the drawings. First, according to the flow of Reference Example 1, the electroless substitution type Au plating 17 is applied to the semiconductor laser chip 1 (FIG. 2A) on which the selective Au plating 13 having a thickness of 1 μm and the selective Sn plating 14 having a thickness of 2.7 μm are formed. Form (FIG. 2-b). The substitutional plating is a plating method in which Au is not plated on the outermost surface of Sn, but Sn is dissolved and Au is replaced thereafter. In the Sn layer whose surface is oxidized, the normal electroplating is weak because the adhesion between Sn and Au is weak and easily peeled off, which is an unstable process. However, according to the above electroless substitution Au plating, Sn The adhesion between Au and Au is strong, and the process can be stabilized. The substitution type Au plating 17 has a thickness of about 0.1 μm and is very thin. Therefore, if the substitution type Au plating 17 is left for a long time, it will be eroded and discolored by the underlying Sn.
An electrolytic Au plating 13 having a thickness of 1 μm is further formed on the plating 17 (FIG. 2C). Thereafter, the resist pattern 12 is removed with a resist stripper (FIG. 2D). At this time, since the Sn plating 14 is protected by the Au plating 13, it is not etched by the resist stripping solution.
According to this embodiment, Au plating is formed on Sn plating, Sn can be protected from oxidation and etching by resist stripping solution, and Sn loss can be prevented, so that the relative value of Au plating amount and Sn plating amount is maintained. Therefore, the composition of AuSn solder can be stabilized and assembly failure can be reduced.
[0013]
Example 2 .
FIG. 3 shows a J-down assembly flow to which the AuSn solder structure according to the present invention is applied. In the figure, reference numeral 18 denotes an active layer side laser electrode.
A method of manufacturing the semiconductor laser device according to this embodiment will be described with reference to the drawings. On the active layer side laser electrode 18, a selective Sn plating 14 having a thickness of 2 μm, an electroless Au plating 17, and a selective Au plating 13 having a thickness of 2 μm are formed in a resist pattern for selective plating in the same manner as in Example 1. After the pattern is removed, it is separated into individual chips by cleavage (FIG. 3-a). Next, the active layer 2 side is placed on the submount 3 on which the Au layer 16 having a thickness of 1 μm is formed (FIG. 3B). When this is processed for a predetermined time in an atmosphere of 340 ° C., Au and Sn are alloyed to form AuSn solder 7. The Au plating layer has a total of 3 μm, the Sn plating layer has a thickness of 2 μm, and Au = 80 wt% AuSn solder is formed.
[0014]
According to the present embodiment, the AuSn solder area can be controlled at the time of forming the resist pattern for selective plating, and further, the amount of AuSn solder can be controlled by the plating film thickness. The yield of J-down assembly can be improved.
[0015]
【The invention's effect】
As described above, according to the present invention, by forming an Au layer on the Sn layer selectively formed by plating in the region excluding the cleavage site, by electroless displacement plating, the Sn layer is formed. An Au film that has strong adhesion and is difficult to peel off can be formed. Furthermore, by forming an Au layer by electrolytic plating, oxidation of the Sn layer and etching with a resist stripping solution can be prevented, so that no cleavage failure occurs. The composition of the AuSn alloy can be stabilized and assembly failures can be reduced. As a result, there is an effect of improving the yield of stack assembly and J-down assembly .
[Brief description of the drawings]
FIG. 1 is a cross-sectional side view showing a stack assembly flow of a semiconductor laser device according to a first embodiment of the invention.
FIG. 2 is a cross-sectional side view showing a flow of a method of manufacturing a semiconductor laser device according to Embodiment 1 of the present invention.
FIG. 3 is a cross-sectional side view showing a flow of J-down assembly of a semiconductor laser device according to Embodiment 2 of the present invention.
FIG. 4 is a cross-sectional side view showing a flow of J-down assembly of a conventional semiconductor laser device.
FIG. 5 is a cross-sectional side view showing a conventional semiconductor laser device with a four-stage stack assembly.
FIG. 6 is a cross-sectional side view showing an example of a conventional semiconductor laser device.
[Explanation of symbols]
1 semiconductor laser chip, 2 active layer, 3 submount,
4 AuSn solder pellets, 5 Au layer on submount,
6 wrapping around AuSn solder, 7 AuSn solder,
8 Sn layer on the semiconductor laser device, 9 Sn layer on the submount,
10 laser electrode, 11 active layer side selective Au plating,
12 resist pattern for selective plating, 13 selective Au plating,
14 Selective Sn plating, 15 cleavage direction, 16 Au on submount,
17 Electroless substitution type Au plating, 18 Active layer side laser electrode.

Claims (3)

A plurality of continuous semiconductor laser chips in which an Au layer is selectively plated on a surface on the active layer side excluding the cleavage site and a laser electrode is formed on the other surface, and Au on one surface Preparing a submount on which the layer is formed and mounting the semiconductor laser chip;
A step of forming a resist pattern at the cleavage site on the laser electrode;
A step of selectively plating an Sn layer on a region excluding the resist pattern on the laser electrode;
Forming an Au layer on the upper layer of the Sn layer by electroless displacement plating, and then forming an Au layer on the upper layer of the Au layer by electrolytic plating;
Removing the resist pattern;
Separating the plurality of continuous semiconductor laser chips into individual semiconductor laser chips by cleavage;
A step of stacking a plurality of the active layers of the semiconductor laser chip on the surface of the submount on which the Au layer is formed;
Stack assembly is performed by a process including a step of forming an AuSn alloy layer by melting an Au layer and an Sn layer interposed between the submount and the semiconductor laser chip, and between the semiconductor laser chips, respectively. A method for manufacturing a semiconductor laser device. Preparing a plurality of continuous semiconductor laser chips having laser electrodes formed on a surface on the active layer side, and a submount on which an Au layer is formed on one surface and mounting the semiconductor laser chip; ,
A step of forming a resist pattern at the cleavage site on the laser electrode;
A step of selectively plating an Sn layer on a region excluding the resist pattern on the laser electrode;
Forming an Au layer on the upper layer of the Sn layer by electroless displacement plating, and then forming an Au layer on the upper layer of the Au layer by electrolytic plating;
Removing the resist pattern;
Separating the plurality of continuous semiconductor laser chips into individual semiconductor laser chips by cleavage;
Placing the active layer side of the semiconductor laser chip down on the surface of the submount on which the Au layer is formed;
J-down assembly is performed by a process including a step of melting an Au layer and an Sn layer interposed between the submount and the semiconductor laser chip to form an AuSn alloy layer. Method. Method of manufacturing a lower layer of the Sn layer, a semiconductor laser device according to claim 1 or claim 2 wherein, characterized in that it comprises the step of selectively plating an Au layer.

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