JPS63209131A - Coating method for fusion-bonding metal in die bonding - Google Patents

Abstract

PURPOSE:To uniformly coat fusion-bonding metal thinly by stretching the metal by the spray pressure of reducing or inert gas, and further removing the excessive metal by the pressure. CONSTITUTION:When fusion-bonding metal 24 of thermally fused state is supplied to the die bonding section 22a of other member 22, the metal 24 remains relatively thick as it is. Then, when reducing or inert gas is sprayed toward the metal 24, the metal 24 is thinly moistened to be spread on the surface of the section 22a by the gas diffusing pressure, and the thickness is uniformized by the fluidity of the metal 24 of fused state. Simultaneously, the excessive metal 24 is blown off by the spraying gas. Thus, a thin and uniform fusion- bonded film is formed.

Description

Detailed Description of the Invention (Objective of the Invention) (Industrial Field of Application) The present invention relates to a method for manufacturing a semiconductor light emitting device such as a semiconductor laser, and relates to a method for manufacturing a semiconductor light emitting device such as a semiconductor laser, etc. by using a fused metal. The present invention relates to a method of applying the fusion metal to a heat sink or the like when performing die bonding to the heat sink or the like.

(Prior Art) As shown in FIG. 4, the semiconductor laser 11 as a semiconductor light emitting device has a main characteristic, the current-light output characteristic, which is very sensitive to temperature. The heat sink 22 has good thermal conductivity such as gold eutectic alloy, lead-
Although tin is lυ, it is necessary to uniformly die-bond it with a fusion metal 24 such as indium.

In this case, the semiconductor laser 11 has dimensions of 0.25
It is very small at X 0.30X 0.1 mtd, and the light emitting part 12 (P-N junction) is very close to the end of the heat sink side (fusion metal side) by 20 to 50 μm. For these reasons, the fusion metal 24 for die-bonding the semiconductor laser 11 to the heat sink 22 needs to be applied uniformly and thinly to the heat sink 22. 13 is a bonding wire.

Conventionally, in order to apply the fusion metal 24, a vacuum evaporation method,
Injection methods using a disbenzer, methods using a metal pellet, etc. have been used, but each of these methods has the following problems.

Although the conventional vacuum evaporation method has excellent uniformity, continuous operation is difficult, and in the heat sink 22 shown in FIG. In this case, it is difficult to cover the insulating material 18 during vapor deposition, and there is a risk that the insulating material 18 will be vapor-deposited and cause insulation failure between the electrodes 16 and 17 and the heat sink 22 (die bonding part 22a). .

Furthermore, in both the conventional injection method using a dispenser and the method using a metal pellet, it is difficult to control the thickness of the welding table 1124. It is difficult to apply the coating uniformly, and this causes short circuits at the joints of the semiconductor lasers 11 and tilting of the semiconductor lasers due to non-uniform thickness, which reduces assembly yield.

Further, as the fusion metal of the semiconductor laser 11, gold-
Gold thread eutectic alloys such as tin, indium, etc. are often used, but these do not necessarily have good wettability with the heat sink 22 when compared to lead-tin solder. Therefore, these fused metals do not thin and spread on the heat sink only by heating, but instead become thickly raised on the upper surface of the die bonding part 22a due to surface tension, as shown in FIG. It is maintained. Therefore, the fusion table WA24a
It is necessary to apply mechanical sliding or the like from the outside to the fused metal without stretching it.

(Problems to be Solved by the Invention) Conventionally, in the case of the vacuum evaporation method, continuous operation was difficult and there were problems such as poor insulation, and in the case of the method using a dispenser or metal pellet, There is a problem in that it is difficult to apply the fusion metal thinly and uniformly.

SUMMARY OF THE INVENTION An object of the present invention is to solve these problems and provide a method for efficiently and uniformly applying a die bonding metal in a thin layer in a continuous operation.

[Structure of the invention]

(Means for Solving the Problems) The present invention, in die bonding in which one member 11 is integrated with the other member 22 using the fusion metal 24, the fusion stand 1i124 in a molten state is Part 5
22, and a reducing or inert gas is sprayed onto the fused metal 24, and the gas is sprayed by pressure to the fused metal 24.
This is a method of applying a fused metal to uniformly obtain a fused metal of a predetermined thickness by stretching 4 thinly and blowing away excess fused metal.

(Function) The present invention provides die bonding portion 22a of the other member 22.
When the fused metal 24 in a heated and molten state is supplied to
Although the fused metal 24 tends to wet and spread on the surface of the die bonding portion 22a due to its own fluidity, it remains relatively thick as it is. Therefore, when a reducing or inert gas is blown toward the fused metal, the blown pressure of the gas causes the fused metal to 24
spreads thinly on the surface of the die bonding part 22a,
The thickness of the fused metal is made uniform due to the fluidity of the molten metal. At the same time, the remaining fused metal is blown away by the gas, and a thin and uniform fused metal film is formed. One member 11 is supplied onto this metal crotch, and when the fused metal solidifies, both members are integrated.

(Example) Hereinafter, the present invention will be explained in detail with reference to the example shown in FIGS. 1 to 3.

FIG. 1 is a schematic diagram of a fusion metal coating device for semiconductor laser die bonding, in which a semiconductor laser 11 (FIG. 5) as one member is fused to a boulder 21 that also functions as a heater for heat sink heating. A heat sink 22 as the other member is fitted, and the tip extraction port 2 of the fusion metal extraction port is placed opposite the fusion metal application surface (upper surface) of the die bonding portion 22a of the heat sink 22.
3 and a distal ejection port 25 of a device that ejects gas for stretching the fusing table R24 supplied from the extraction port 23 onto the application surface to a constant thickness.

Then, the heat sink 22, which has been preheated by another heating means (not shown), is set in the main heating holder 21, as shown in FIG. 1, and heated to the melting point of the fusion metal 24. Next, the semiconductor laser die bonding portion 22a1. of this heat sink 22. : When a high-temperature fusion metal that is heated and in a molten state is supplied from the fusion metal extraction port 23, the fusion metal 24 wets and spreads on the surface of the die bonding part 22a due to its own fluidity. Even if there is a tendency, if left as it is, it will remain relatively thick and raised as shown by 24a in FIG.

Therefore, at the same time as this fusion metal is supplied, a reducing gas such as forming gas or an inert gas such as nitrogen is ejected from the ejection port 25, and the die bonding portion 2
When the gas is sprayed onto the fused metal 24a on the 2a, the fused metal thinly spreads over the entire surface of the bonding part 22a due to the pressure of the sprayed gas, and the thickness becomes uniform due to the fluidity of the fused metal. be done. At the same time, the remaining excess welding metal is blown away from the coated surface by the pressure of the ejected gas, and a thin and uniform thin film of welding metal 24b is formed as shown in FIG. The semiconductor laser 11 (FIG. 5) is placed on this fused metal film, and the die bonding portion 22a and the semiconductor laser 11 are bonded to F! by the fused metal 24b. & be looked after.

The reducing nature and inertness of the gas serves to prevent oxidation of the fused metal.

In the experiment, lead-tin solder (W & point 18) was used as the fusion metal.
When using a heating temperature of 220°C and a nitrogen gas pressure of 3 K9/cri, it was possible to uniformly apply a ms metal film with a thickness of 8 to 12 μm.

〔Effect of the invention〕

According to the present invention, the fusion metal is stretched by pressure when the reducing or inert gas is sprayed, and excess metal is removed using this pressure, so the fusion metal can be applied thinly and uniformly. For example, short circuits at the joints of semiconductor light emitting devices (semiconductor lasers) caused by uneven thickness of the fused metal,
Problems such as poor assembly due to inclination etc. are solved. Further, since the fused metal spreads wetly on the coating surface due to the pressure of the gas, there is no need to mechanically stretch the fused metal, and continuous work can be carried out efficiently. Furthermore, there are no problems such as poor insulation that occur with vacuum evaporation methods.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing an embodiment of the fusion metal application method of the present invention, and Fig. 2 shows the state of the fusion metal before gas blowing.
Figure 3 is a perspective view (not showing the wetting and spreading state of the welded metal according to the conventional method), and Fig. 3 shows the state B (wetting and spreading of the welded metal according to the present invention) in which the welded metal is stretched by the pressure applied to the gas spray. FIG. 4 is a perspective view showing a portion to which a semiconductor laser is die-bonded, and FIG. 5 is a perspective view of a heat sink to which a semiconductor laser is die-bonded. 11... Semiconductor laser as one member, 22...
Heat sink as the other member, 24... fused metal. Kagura 4 and Kagura 5 fields

Claims (2)

[Claims] (1) In die bonding, in which one member is integrated with another member using a fusion metal, the fusion metal in a molten state is supplied to the other member, and the fusion metal has a reducible or inert property. In die bonding, which is characterized by uniformly obtaining a predetermined thickness of the fused metal by stretching the fused metal thinly by blowing gas and blowing off and removing excess fused metal. How to apply fused metal. (2) Die bonding according to claim 1, characterized in that a semiconductor light emitting device such as a semiconductor laser as one member is die-bonded to a heat sink for heat dissipation as the other member using a fusion metal. How to apply fused metal in.