JPS5828755B2 - semiconductor equipment - Google Patents

Abstract

PURPOSE:To adhere a heat spreader composed of two kinds of metal to a heat sink hard enough in a region except the operating region of a semiconductor chip, without causing strain near the operating region. CONSTITUTION:On electrode 8 near luminous part 10 of semiconductor chip 1, metal layer 12 is formed approximate three times as wide as luminous part 10. This layer, plated with silver, copper, etc., is large in thermal conductivity and hard to be alloyed with In solder. On the remaining part on electrode 8, gold layer 13 is selectively formed which is easy to be alloyed with In. Heat spreaders 12 and 13 are mounted on heat sink 14 and then fixed by solder 15 and, in consequence, the solder remains as soft metal In is since layer 12 is never alloyed, so that no strain will appear in the active region of the chip. As a result, layer 13 is alloyed with In and comes in hard contact with the heat sink.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semiconductor device, and particularly to a structure for soldering a semiconductor chip to a metal body such as a heat sink.

It is extremely important to adhesively mount a semiconductor chip on a heat sink without causing distortion to the semiconductor chip in order to maintain good operating characteristics of the semiconductor device.

A semiconductor laser device will be explained below as an example.

Normally, the electrode side of a semiconductor laser chip, which is closer to the heat generating part, is thermally fused to a heat sink in order to increase the heat dissipation effect.

In this case, indium, which is a soft metal, is widely used as a solder material in order to prevent distortion of the chip.

However, indium does not have sufficient adhesive strength, and over time, the heat sink and semiconductor laser chip peel off, causing the heat sink to lose its function and causing the temperature of the semiconductor laser chip to rise. An undesirable phenomenon of deterioration of characteristics occurs.

On the other hand, in order to increase the adhesive strength, for example, tin Sn, gold/tin Au
The use of hard solder materials such as Sn alloys and gold-silicon AuSi alloys induces large strains within the chip, which also causes rapid characteristic deterioration of the chip.

Therefore, it is not possible to directly bond a semiconductor laser chip to a heat sink using these solder materials.

Therefore, a method of providing a heat spreader on the electrodes of the chip has been conventionally used as a method of dealing with such problems.

FIG. 1 is a sectional view showing an example of a conventional device, and this semiconductor laser chip 1 is manufactured as follows.

That is, an n-type gallium-aluminum-arsenide GaAlAs layer 3, a p-type GaAs layer 4, and a p-type GaAlAs layer 5 are sequentially grown on an n-type gallium-arsenide GaAs substrate 2 by a liquid phase growth method, and a current is concentrated. Electrodes 8 and 9 are provided after a zinc diffusion region 7 is formed using an insulating mask 6 in the area to be exposed.

In such a semiconductor laser chip 1, a current concentration portion of the P-type GaAs layer 4 forms a light emitting portion 10.

Therefore, in order to improve the heat dissipation effect, the light emitting section 10
A heat spreader 11 made of a metal layer with high thermal conductivity is formed on the electrode 8 near the electrode 8 .

This heat spreader 11 is made of a metal layer with a thickness of 5 to 10 μm, and has the function of spreading the heat flow generated in the light emitting part 10 and flowing through the semiconductor layer laterally, and then flowing it into the heat sink bonded thereon. .

Therefore, even if the adhesion to the chip is not good or if a part of the chip peels off, the heat will spread within the heat spreader 11 and then flow into the heat sink.
An extreme increase in thermal resistance is prevented.

However, in the method using this heat spreader 11,
Since the metal layer constituting the heat spreader 11 is thick, alloying with indium, which is a solder material, rapidly progresses during thermal fusion of the heat sink, leaving large distortions and causing characteristic deterioration of the laser chip 1. It was often the case.

Therefore, in order to prevent the above-mentioned alloying, there has been an attempt to construct the heat spreader 11 with silver, etc., which is difficult to form an alloy with indium, but the fact that alloying is difficult to occur means that
This meant that the adhesive strength was low, and there were many problems in this respect.

This invention was made in view of the above points, and by configuring the heat spreader with two types of metals,
It is an object of the present invention to provide a structure of a semiconductor device in which a desired adhesive strength with a heat sink can be obtained in other regions without causing distortion in the vicinity of the operating region of a semiconductor chip.

FIG. 2 is a perspective view showing the structure of an embodiment of the present invention, and the semiconductor laser chip 1 is the same as that used to explain the conventional device in FIG.

For example, the light emitting part 1 is placed on the semiconductor laser chip 10 on the electrode 8 on the side closer to the light emitting part 10 so that the width of the light emitting part 100 is x5.
A first metal layer 12 having a width of 1.0 to 3.0 times the 00 width is formed.

This first metal layer 12 is made of a metal that has high thermal conductivity and is difficult to alloy with indium solder material, such as silver, copper, etc.
It is convenient to form it by plating aluminum, nickel, etc.

Next, a second metal layer 13 made of gold, which is easily alloyed with indium, is selectively formed on a portion of the electrode 8 where the first metal layer 12 is not formed.

In this case, it is naturally desirable that the first metal layer 12 and the second metal layer 13 have the same thickness, and the appropriate thickness is 5 to 10 μm as described above.

FIG. 3 is a cross-sectional view showing the state in which the semiconductor laser chip of this embodiment is mounted on a heat sink. The laser chip 1 is mounted using a solder material 15.

With such a configuration, when the temperature is increased during the thermal fusion process to the heat sink 14, the gold constituting the second metal layer 13, which easily alloys with the indium that is the solder material 15, becomes a gold-indium alloy. It is firmly adhered to the heat sink 14.

On the other hand, since alloying with indium does not progress in the first metal layer 12 of the active region of the semiconductor laser chip 1, the solder material 15 exists in the form of soft metal indium, which acts as a buffer. , no distortion is introduced into the active region of the semiconductor laser chip 10, the light emitting section 10, etc.

Although the above embodiments have been described as being applied to semiconductor laser chips, this invention can also be widely applied to semiconductor devices such as light emitting diodes, Gunn diodes, and invat diodes. Of course, the shape is not limited to the rectangle in the embodiment.

As detailed above, in this invention, near the active region of the semiconductor chip that generates heat, the first metal layer is provided where the solder material is less likely to alloy and harden, so this region is strained. In addition, since the second metal layer is provided in other parts where the solder material is easily alloyed,
...The adhesive strength with the heat sink bonded using the soldering material can be ensured sufficiently in this part.

Therefore, a semiconductor device with good heat dissipation effect can be obtained without impairing the characteristics of the semiconductor chip.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of a conventional device, FIG. 2 is a perspective view showing an embodiment of the present invention, and FIG. 3 is a sectional view showing this embodiment mounted on a heat sink. In the figure, 1 is a semiconductor chip, 8 and 9 are electrodes, 10 is a light emitting part (heat generating part), 12 is a first metal layer, 13 is a second metal layer, 14 is a heat sink, and 15 is a solder material. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] 1. In a device in which a semiconductor chip is bonded to a heat sink via a solder material to dissipate heat generated within the semiconductor chip, an electrode provided on the surface of the semiconductor chip on the side closer to the heat generating part within the semiconductor chip. A first metal layer that is difficult to alloy with the solder material is placed on the part facing the active area that generates heat, and a second metal layer that is easy to alloy with the solder material is placed on the other part of the electrode. 1. A semiconductor device comprising a heat sink bonded to the upper surfaces of the first and second metal layers via the solder material.