JPH06163612A - Manufacture and equipment for semiconductor device - Google Patents

Abstract

PURPOSE:To make the thickness of molten solder even, for thermally treating a three-layer solder far jointing a semiconductor element with a supporter body. CONSTITUTION:A three-layer solder 3, wherein on bath sides of the first solder 3a made of a high melting point material, the second solder 3b made of the material whose melting point is lower than the first solder 3a is assigned, is sandwiched between a semiconductor element 1 and a supporter body 2 on which the element 1 is mounted, and then a pressure is applied on the three- layer solder 3 by a weight 5, so that, through heating and thermal treatment, only the second solder 3b is melted far jointing the semiconductor element 1 with the supporter body 2. With this, the thermal treatment period required for making the three-layer solder of higher melting paint can be shortened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device and a manufacturing apparatus for bonding a semiconductor element and a support on which the semiconductor element is mounted by heat treatment.

[0002]

2. Description of the Related Art FIG. 5 is a sectional view showing the structure and manufacturing process of a conventional semiconductor device similar to that disclosed in, for example, Japanese Patent Application No. 3-4832.

In FIG. 5, reference numeral 1 is a semiconductor element, 2 is a support on which the semiconductor element is mounted, for example a die pad, and 3 is a three-layer solder for joining the semiconductor element 1 and the die pad 2. Is 95Pb-5Sn and has a thickness of 50 μm and high melting point (305 ° C.) solder (first solder) 3a
And the upper and lower surfaces of the high melting point solder 3a are formed by plating, vapor deposition, sputtering, or the like, and have a composition of Pb-6, for example.
Eutectic solder (second solder) 3b with 3Sn and a thickness of 10 μm
Consists of.

Reference numeral 4 is a heat block for heating the mounted die pad 2, but this is not a part of the semiconductor device.

In such a semiconductor device, the semiconductor element 1
And the die pad 2 are overlapped with each other via the three-layer solder 3, and the melting point of the eutectic solder 3b is 183 ° C. or higher and the melting point of the high melting point solder 3a is 305 ° C. or lower in a reducing atmosphere, for example, 200
The semiconductor block 1 and the die pad 2 are bonded by heating to ℃ by the heat block 4 to melt only the eutectic solder 3b.

Then, by maintaining the above-mentioned temperature of 200 ° C., P between the eutectic solder 3b and the high melting point solder 3a is obtained.
b and Sn cause mutual diffusion, and as can be seen from the Pb-Sn system phase diagram in FIG. 6, solidification occurs when the Sn concentration in the eutectic solder 3b is about 18% or less, that is, when the Pb concentration is about 82% or more. .

Further, when the temperature is increased to a temperature just below the solidus temperature as the Sn concentration is lowered, the diffusion rate of Sn is further accelerated. Finally, as shown in FIG. 6, the high melting point solder 3a
And the eutectic solder 3b have the same solder composition, and the melting point of the three-layer solder 3 is higher than that of the eutectic solder 3b in the initial state.

Therefore, in addition to the effect of keeping the distance between the semiconductor element 1 and the die pad 2 constant by not melting the high melting point solder 3a, it also has heat resistance higher than the heating temperature of 200 ° C. at the time of joining. A semiconductor device can be obtained.

After the semiconductor element 1 and the die pad 2 are joined, the semiconductor device is taken out from the heat block 4 and an electrode (not shown) on the semiconductor element 1 and an external lead (not shown) are connected by a gold wire (not shown). The semiconductor device is completed through various steps such as a wire bonding step and a molding resin sealing step of sealing the semiconductor device.

[0010]

In the conventional semiconductor device as described above, during the heating for melting the eutectic solder 3b of the three-layer solder 3 and during the heat treatment in which Pb and Sn interdiffuse thereafter. , No stress acts between the semiconductor element 1 and the die pad 2, and the semiconductor element 1 melts the eutectic solder 3b.
It is floating above.

Therefore, in reality, the melted eutectic solder 3b flows and the eutectic solder 3 on the semiconductor element 1 side and the die pad 2 side is melted.
Variation occurs in the thickness of b, and as a result, the thickness of either one of the eutectic solders 3b increases.

The melting point of the three-layer solder 3 is controlled by the thicknesses of the eutectic solder 3b and the high melting point solder 3a.
Since it is determined by the composition ratio of b and Sn, three-layer solder 3
It can be said that the melting point of is controlled by the thickness of the eutectic solder 3b and the high melting point solder 3a.

Therefore, if the thickness of the eutectic solder 3b is large when the melting point of the three-layer solder 3 is increased and the thickness of the eutectic solder 3b varies, the required heat treatment time also correlates well with the measured value in FIG. As can be seen from the simulation results obtained, there was a problem that not only the variation but also the heat treatment for a long time was necessary.

Incidentally, if the thickness of the eutectic solder 3b provided on the three-layer solder 3 is 10 μm, there is a difference in thickness between the semiconductor element 1 side and the die pad 2 side of the eutectic solder 3b after heating and melting. The thickness was about 10 μm. For example, the eutectic solder thickness on the semiconductor element side was 5 μm, while the eutectic solder thickness on the die pad side was 15 μm. For this reason, the heat treatment time is controlled to the thicker side of the eutectic solder, which requires several hours more than the originally expected heat treatment time. (See Figure 7)

The thickness of the eutectic solder 3b is, for example, 10 μm.
When the temperature of the furnace for heat treatment that performs mutual diffusion of Pb and Sn is set to a certain temperature as m, when the difference in the thickness of the eutectic solder 3b is varied as described above, the die pad of 15 μm is used. The side eutectic solder is not sufficiently solidified due to insufficient heat treatment time in the heat treatment stage when the temperature in the subsequent wire bonding step or the like is higher than the set temperature in the furnace,
There is a problem that the semiconductor element 1 is melted and floats on the eutectic solder on the die pad side, and wire bonding cannot be performed.

The present invention has been made in order to solve the above problems, and increases the melting point of the three-layer solder by making the thickness of the molten solder when heat treating the three-layer solder thin and uniform. It is an object of the present invention to provide a method and an apparatus for manufacturing a semiconductor device, which can shorten the heat treatment time required for the above and do not hinder the processing in the subsequent steps.

[0017]

According to the method of manufacturing a semiconductor device of the present invention, the first solder made of a high melting point material is formed on both surfaces of the first solder.
The three-layer solder, in which the second solder made of a material having a melting point lower than that of the first solder is arranged, is sandwiched between the semiconductor element and the support on which the semiconductor element is mounted, and the three-layer solder is pressed. Is added, and only the second solder is melted by heating and heat treatment to bond the semiconductor element and the support.

Further, the semiconductor device manufacturing apparatus of the present invention comprises a pressurizing means for applying pressure to the three-layer solder sandwiched between the semiconductor element and the support on which the semiconductor element is mounted. is there.

[0019]

According to the method of manufacturing the semiconductor device of the present invention,
Since the pressure is applied to the three-layer solder when heating and heat-treating the three-layer solder sandwiched between the semiconductor element and the support, the thickness of the melted solder can be made thin and uniform, The heat treatment time required for raising the melting point of the three-layer solder can be shortened, and the subsequent steps can be performed without any trouble.

In the semiconductor device manufacturing apparatus of the present invention, the pressure is applied to the three-layer solder by the pressing means during the heat treatment. This makes it possible to shorten the heat treatment time required for raising the melting point of the three-layer solder with a simple structure, and to perform the post-process without any trouble.

[0021]

【Example】

Example 1. An embodiment of the present invention will be described below. FIG. 1 is a sectional view showing an embodiment of the present invention.

In FIG. 1, 1, 2, 3, 3a, 3b,
Reference numeral 4 is the same semiconductor element, die pad, three-layer solder, high melting point solder (first solder), eutectic solder (second solder), and heat block as in the conventional example. Reference numeral 5 is a weighting weight placed on the semiconductor element 1.

As described above, the three-layer solder between the semiconductor element 1 and the die pad 2 is subjected to pressure, that is, weighted and subjected to the same heat treatment as in the conventional case, so that the semiconductor element 1 and the die pad 2 are excessively bonded. The eutectic solder 3b is discharged to the side surface, and the entire eutectic solder thickness is reduced. As a result, the difference in thickness between the semiconductor element 1 side and the die pad 2 side of the eutectic solder 3b after heating and melting converges within about 2 μm. did. For example, according to experiments, the eutectic solder thickness on the semiconductor element side was 6 μm, while the eutectic solder thickness on the die pad side was 4 μm.

As described above, in the present embodiment, the heat treatment time can be shortened by several hours by reducing the eutectic solder thickness and making the thickness almost uniform. In addition, since the eutectic solder thickness can be made almost uniform, it does not happen that the solidification is not sufficiently solidified by not reaching the set temperature in the furnace due to insufficient heat treatment time in the conventional heat treatment step, so that it melts in the subsequent wire bonding process. As a result, the problem that the semiconductor element 1 floats on the melted eutectic solder and wire bonding becomes impossible is eliminated.

Example 2. FIG. 2 is a sectional view showing another embodiment of the present invention. Although the weight is directly placed on the semiconductor element 1 as the pressing means in the first embodiment, a jig 6 having a weighting function as shown in FIG. 2 may be used.

In FIG. 2, 6a is a spring for weighting between the semiconductor element 1 and the die pad 2 attached to the lower surface of the jig 6, and 6b is attached to the spring 6a and melts on the surface of the semiconductor element 1. It is a flat plate for uniformizing the weight by applying.

As described above, also in this embodiment, the same effect as that of the first embodiment can be obtained by heating and heat treating the semiconductor device weighted by the jig 6.

Example 3. FIG. 3 is a sectional view showing another embodiment of the present invention. In FIG. 3, 7 is an atmosphere furnace main body, 8 is an atmosphere gas ejected from the furnace, 9 is a silicon rubber for weighting, and 10 is a belt conveyor. The semiconductor devices are arranged on the belt conveyor 10 at a predetermined interval and fed into the furnace.

In the furnace, a convex weighting object made of silicon rubber 9 or the like is provided on the in-furnace belt conveyor 10 so as to correspond to each semiconductor device, whereby the semiconductor element 1 and the die pad 2 are connected. You can weight between. Further, the weighting degree can be changed by changing the convex shape.

As described above, also in this embodiment, the heat treatment time required for manufacturing the semiconductor device can be shortened by several hours, and the heat treatment can be efficiently carried out by the flow work without any trouble in the subsequent steps.

Example 4. FIG. 4 is a sectional view showing another embodiment of the present invention. A furnace 11 as shown in FIG. 4 may be used instead of the semiconductor device manufacturing apparatus of the third embodiment. In FIG. 4, reference numeral 12 is a gas injection valve for pressurizing the furnace. By injecting the gas into the furnace 11, the pressure inside the furnace can be increased, and thereby, the weight can be applied between the semiconductor element 1 and the die pad 2.

As described above, in this embodiment as well, the heat treatment time can be shortened and there is no hindrance to the subsequent steps, as in the above embodiments.

[0033]

As described above, according to the method of manufacturing a semiconductor device of the present invention, the second solder made of a material having a melting point lower than that of the first solder is formed on both surfaces of the first solder made of a high melting point material. Sandwiching the three-layer solder having the above-mentioned solder disposed between the semiconductor element and the support on which the semiconductor element is mounted, applying pressure to the three-layer solder, and heating and heat treating only the second solder. Since the semiconductor element and the support are melted and joined together, the thickness of the molten solder during the heat treatment can be made thin and uniform, and the heat treatment time required for increasing the melting point of the three-layer solder can be shortened. At the same time, there is an effect that the subsequent process is not hindered.

Further, according to the semiconductor device manufacturing apparatus of the present invention, since the semiconductor element and the support on which the semiconductor element is mounted are provided with the pressurizing means for applying pressure to the three-layer solder,
With a simple configuration, there is an effect that the heat treatment time required for raising the melting point of the three-layer solder can be shortened without causing any trouble in the subsequent steps.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a sectional view showing another embodiment of the present invention.

FIG. 3 is a sectional view showing another embodiment of the present invention.

FIG. 4 is a sectional view showing another embodiment of the present invention.

FIG. 5 is a cross-sectional view showing a conventional semiconductor device manufacturing apparatus.

FIG. 6 is a state diagram for explaining a solidification process of three-layer solder.

FIG. 7 is a diagram showing a simulation result of a relationship between a thickness of eutectic solder and a heat treatment time.

[Explanation of symbols]

 1 semiconductor element 2 die pad 3 three layer solder 3a high melting point solder (first solder) 3b eutectic solder (second solder) 4 heat block 5 weight for weight 6 jig 6a spring 6b flat plate 7 furnace 9 weight silicon Rubber 11 Furnace 12 Gas injection valve for pressurizing inside the furnace

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[Procedure amendment]

[Submission date] July 8, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0024

[Correction method] Change

[Correction content]

As described above, in the present embodiment, the heat treatment time can be shortened by several hours by reducing the eutectic solder thickness and making the thickness almost uniform. Further, since the eutectic solder thickness can be made substantially uniform, it is possible to prevent the melting point of the entire three-layer solder from being insufficiently increased due to insufficient heat treatment time in the heat treatment step as in the conventional case, and therefore in the subsequent wire bonding step. And the semiconductor element 1 floats on the melted eutectic solder and wire bonding is no longer possible.

Claims (2)

[Claims] 1. A three-layer solder, in which a second solder made of a material having a melting point lower than that of the first solder is provided on both surfaces of a first solder made of a high melting point material, a semiconductor element and the semiconductor The device is sandwiched between the supports on which the device is placed, pressure is applied to the three-layer solder, and only the second solder is melted by heating and heat treatment so that the semiconductor device and the support are joined. A method for manufacturing a characteristic semiconductor device. 2. An apparatus for manufacturing a semiconductor device, wherein a three-layer solder sandwiched between a semiconductor element and a support on which the semiconductor element is mounted is heated and heat-treated to bond the semiconductor element and the support. An apparatus for manufacturing a semiconductor device, comprising pressurizing means for applying pressure to the three-layer solder.