JPH06188328A - Semiconductor device and assembly method thereof - Google Patents

Abstract

PURPOSE:To lower a thermal resistance and to enhance the reliability of an element by a method wherein a substance whose thermal conductivity is excellent is liquefied and filled into a gap at the bonding face of an uneven metallized substrate to a semiconductor chip by utilizing a capillary phenomenon. CONSTITUTION:A groove part 3 for electrode isolation is formed in a metallized substrate 1 provided with an electrode pattern 4, an electrode pattern 5 for a semiconductor chip 2 is aligned with it, and a face-down bonding operation is performed. An insulating filler 6 is applied in advance to one part of the groove part at the outside of the semiconductor chip 2. The filler is melted by heating in the bonding operation, it is conveyed in the groove part due to a capillary phenomenon, and a thermal resistance between the semiconductor chip and the metallized substrate is reduced. Since the heat-dissipating property of the semiconductor chip is improved, the reliability of an element can be enhanced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device and its mounting method, and more particularly to a method of assembling a semiconductor laser.

[0002]

2. Description of the Related Art A multi-beam semiconductor laser has been developed as a light source for a high-speed optical disk device. In such assembly and mounting of the laser array and the submount, in order to independently drive each laser, a complicated heat sink having an electrode pattern corresponding to the electrode pattern of the laser chip is required. Moreover, since a plurality of laser elements are operated simultaneously, a submount having a high heat dissipation effect is required. On the laser chip side, since each element is driven independently, a groove for electrode separation is provided between the arrays by etching. The distance between each element is 50 μm, depending on the application
Since it is as narrow as one hundred and several tens of μm, high precision is required also in the alignment at the time of chip-down mounting of the chip.

As described above, compared with a single-beam laser, the submount design, laser chip manufacturing process, and mounting are complicated, and the yield as an element is low.

[0004]

In the arraying of lasers, a plurality of lasers are integrated into a single chip with a narrow interval. Therefore, thermal interference between individual laser elements raises the temperature of the active layer, shortens the life, and oscillates. Characteristic variations such as wavelength drift have become a serious problem.

In view of the above, the present invention reduces the thermal resistance by liquefying a material having excellent thermal conductivity in the gap between the joint surface of the metallized substrate having irregularities and the semiconductor chip and filling it by utilizing the capillary phenomenon. A semiconductor device having a highly reliable element and a method for assembling the same are provided.

[0006]

[Means for Solving the Problems] By liquefying a substance having excellent thermal conductivity and filling it in a gap between a joint surface of a submount and a semiconductor chip by utilizing a capillary phenomenon, the thermal resistance is lowered, Improve the reliability of.

[0007]

[Function] By forming a groove in the submount, heat dissipation from the laser is effectively performed, and even if one laser is turned on and the other laser is turned on, the temperature rise due to thermal interference is reduced, The change in the optical output of the laser is reduced, which is improved compared to the conventional case.

The method of filling the insulating filler 6 in the groove is also
By heating at the time of die bonding, it is melted and automatically propagates through the groove due to the capillary phenomenon to fill the space between the laser chip and the submount.

[0009]

Embodiments of the present invention will be described below with reference to the illustrated embodiments.

FIG. 1 is a schematic diagram of a semiconductor device according to an embodiment of the present invention. In this example, two laser elements are integrated on one semiconductor laser chip 2. Although not shown in detail in the drawing, the semiconductor laser chip 2 has two elements, which are separated by a V-type mesa. The distance between the two laser elements is 50 μm and the depth is about 10 μm.
It is electrically separated by a μm groove. The separation groove is covered with a SiO ₂ film instead of the electrode metal.

On the other hand, the upper and lower surfaces of the submount are Ti / Pt /
It is metallized with Au, but the sides are not metallized, so it is electrically insulated. Pb / Sn solder for adhesion to a heat sink is vapor-deposited on the upper and lower surfaces. The upper surface of the side to be joined to the semiconductor laser chip is partially covered with Pb in a slightly larger area than the laser chip.
The electrode pattern 4 of / Sn solder is vapor-deposited. further,
Corresponding to the electrode pattern 5 of the semiconductor laser chip, a groove 3 for electrode separation is provided at the center of the electrode pattern 4. The width of the groove 3 is 30
It is as narrow as μm. The depth is about 5 to 10 μm.

An insulating filler 6 having excellent thermal conductivity is previously attached to the groove portion 3. As the material of the insulating filler 6, a mixture of AlN, BN and diamond powder having a particle size of 2 to 5 μm with a binder material such as polyimide resin was used. This powder is also excellent in thermal conductivity other than these materials. Any substance can be used. The melting point of this binder is set to 10 to 20 ° C. higher than the temperature at the time of die bonding of the laser chip. The semiconductor laser chip 2 is face-down bonded to the submount 1 at a temperature slightly higher than the melting point of the solder. When the temperature of the submount is raised by 20 to 30 ° C. at the time when bonding is completed by combining the respective electrode patterns,
The insulating filler 6 is melted, flows out along the groove 3 in a few seconds, and the space between the laser chip and the submount is filled with the insulating filler 6 by the capillary phenomenon.

Next, how the characteristics of the laser device are improved will be described with reference to experimental results with reference to FIG. As described with reference to FIG. 1, two laser elements (LD1 and LD2) are integrated on one semiconductor laser chip, and are mounted in the configuration shown in FIG. Each laser can be driven independently.

FIG. 2A shows the light output-current characteristics of the LD 2 when there is a space in the groove portion 3 of FIG. The oscillation threshold current is 42 mA and the optical output is 3 when LD1 is off.
Linearity is maintained up to 0 mW and above. The characteristic temperature when driving only LD2 was 120K. This value is about 20 K lower than the value of the single-beam semiconductor laser having the same structure, and it is considered that the space of the groove 3 deteriorates the heat dissipation characteristic.

When the light output of LD1 is set to 30 mW and the LD2 is operated at a constant current, the light output-current characteristics of LD2 show that the threshold current increases by about 3 mA and the light output tends to be saturated at 20 mW or more. Was given. At the same time, it can be seen that the light output of LD1 also greatly decreases as the drive current of LD2 increases, as indicated by the broken line.

From the characteristic temperature of LD2 and the amount of increase in the threshold current, the temperature rise in the vicinity of the active layer of LD2 by LD1 is estimated to be around 10 ° C. When the current is further increased, the temperature of the active layer further rises due to the interaction of thermal interference, so that the influence of the temperature rise becomes 10 ° C. or more.

FIG. 2B shows L when the space of the groove portion 3 in FIG. 1 is filled with the insulating filler 6 having excellent thermal conductivity.
The optical output-current characteristic of D2 is shown. Due to the improvement of the heat radiation effect, the temperature rise due to thermal interference is reduced, and the characteristics when the LD1 is on are considerably improved. This is a method of filling the groove with the insulating filler 6, but it is melted by heating at the time of die bonding and automatically propagates through the groove by a capillary phenomenon to fill the space between the laser chip and the submount.

[0018]

As described in detail above, according to the present invention, the thermal resistance between the semiconductor chip and the submount is reduced.
Since the heat dissipation characteristics of the semiconductor chip are improved, the reliability of the device can be improved. Also, the assembly method for that is simple,
The effect is great because it can be carried out without significantly changing the conventional process.

[Brief description of drawings]

FIG. 1 is a schematic view of a semiconductor laser device showing an embodiment of the present invention.

FIG. 2 is a drawing for explaining the operation and effect of the present invention.

[Explanation of symbols]

 1 Submount 2 Semiconductor Chip 3 Groove 4 Electrode Pattern (Submount) 5 Electrode Pattern (Semiconductor Chip) 6 Insulating Filler

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor, Yuzaburo 1006, Kadoma, Kadoma, Osaka Prefecture, Matsushita Electric Industrial Co., Ltd. (72) Kiyoji Ohnaka, 1006, Kadoma, Kadoma, Osaka, Matsuda Electric

Claims (4)

[Claims] 1. A semiconductor device in which a semiconductor chip, a submount, and a heat sink are joined by soldering at high temperature to form a heat dissipation structure, and a gap formed between the joining surfaces is filled with a substance having excellent heat conduction. A semiconductor device characterized in that 2. A method for assembling a semiconductor device, wherein a filling substance is filled in the gap by utilizing a capillary phenomenon. 3. A method for assembling, wherein the filling material according to claim 1 is placed on a submount in advance, and its melting point is higher than the die bond temperature of the semiconductor chip and the submount. 4. The filling material according to claim 1, wherein the binder material having the melting point according to claim 3 is uniformly mixed with fine particulate material having excellent thermal conductivity. Semiconductor device.