JPS6255705B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semiconductor device (referred to as a glass sleeve type semiconductor device) having a structure in which a glass sleeve is welded to clamp a semiconductor chip and external extraction electrodes extending to both ends of the semiconductor chip.

The glass sleeve type semiconductor device is shown in Figures 1 and 2.
As shown in the figure, a semiconductor 6, which is usually made of silicon and has a predetermined pn junction, and a heat source formed on at least one main surface of the semiconductor,
A semiconductor chip 1 composed of a metal electrode portion 5 with good electrical conductivity and the other metal electrode film 7;
A pair of external extraction electrodes 2 present at both ends
(For example, an alloy of iron and nickel is present in the center, and the alloy is covered with a copper tube, which is a conductive material. Borax is baked into the welded part of the glass sleeve 3, so that it does not wet with the glass.) ) and a pair of lead wires 4 (copper wires are used, for example) with good conductivity, which are welded to one end of each of the external extraction electrodes 2 and have an integral structure with the external extraction electrodes. and the glass sleeve 3.

When manufacturing such a glass sleeve type semiconductor device, the semiconductor chip 1, the external lead-out electrodes 2 and lead wires 4 integrally formed at both ends are placed in a predetermined relationship, and the external lead-out electrodes 2 at both ends are placed in a predetermined relationship.
The glass sleeve 3 is fixed using a jig made of heat-resistant carbon or the like so as to enclose the glass sleeve, and is kept in an inert atmosphere at a temperature sufficient to melt the glass sleeve for the necessary time, until the glass sleeve melts. This is followed by a cooling process. When cooled to a certain temperature, the glass sleeve 3 is fixed to the external lead electrode 2. Since the main surface area of the semiconductor chip is usually smaller than the area of the external lead electrodes, the glass and the semiconductor chip are not directly bonded to each other.

During the cooling process below the fixing temperature of the glass sleeve, the apparent coefficient of thermal expansion of the glass sleeve is usually larger than that of the entire semiconductor chip and that of the glass sleeve. 1 is pressed from both ends thereof, and the semiconductor chip 1 and the external lead electrode 2 are electrically and mechanically connected to have a function as a semiconductor device.

As mentioned above, the pressure bonding strength of this type of semiconductor device is determined by the difference in thermal expansion coefficient between the semiconductor chip and the glass sleeve, but if the pressure bonding force is weak, it will be weak against tensile force applied from outside, and conversely, the pressure bonding force will be weak. If it is too strong, there is a drawback that the metal electrode member formed on the semiconductor chip may deteriorate due to warp deformation or the glass sleeve may be damaged due to residual stress.

Therefore, how the pressure contact force is controlled greatly influences the reliability of the device with this structure.

The present invention aims to improve the reliability of a semiconductor device by making the pressing force on the semiconductor chip moderate, and without changing the conventional manufacturing method of glass sleeve type semiconductor devices. This makes it possible to improve the reliability of the semiconductor device.

According to experiments conducted by the present inventors, the relationship between the hardness of the electrode material and the pressure contact force is as shown in FIG. From this result, it was confirmed that when the Vickers hardness of the metal electrode formed on the semiconductor chip becomes 20 or less, the pressure applied to the semiconductor chip decreases rapidly. Furthermore, as a result of investigating the cause of the decrease in pressure contact force, it was found that if the hardness of the electrode material is too low, the electrode material will be deformed by the pressure contact force applied from the sleeve during element manufacturing, reducing the actual tightening allowance. I understood.

Furthermore, according to other experiments conducted by the present inventors, the relationship between the hardness of the electrode and repeated thermal fatigue is shown in FIG. It has been confirmed that when the number of defects exceeds 50, the failure rate due to repeated thermal fatigue of the semiconductor device increases rapidly.

In the above experiments, Ag formed by plating was used as the metal electrode, and by varying the plating conditions, heat treatment conditions, etc., several types of experimental samples with different Vickers hardness were prepared.

From the above, it is clear that the optimum value of the Vickers hardness of the metal formed on the semiconductor according to the present invention is in the range of 20 to 50.

According to the present invention, in the semiconductor chip manufacturing process, the Vickers hardness of the metal electrode on the semiconductor is 20
By manufacturing a glass sleeve type semiconductor device according to a conventional process using a semiconductor chip manufactured to have a temperature in the range of .about.50, the reliability of the glass sleeve type semiconductor device can be improved.

In addition, although the case where Ag is used as the metal electrode material has been described above, it is obvious that other metal materials can also be used, and the hardness can be controlled by changing the metal film adhesion conditions and heat treatment conditions. is possible.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a glass sleeve type semiconductor device, Fig. 2 is a sectional view of a semiconductor chip, and Fig. 3 is a sectional view of a glass sleeve type semiconductor device.
Regarding the Vickers hardness of metal electrodes on semiconductors,
A diagram showing the relationship between the pressure contact force applied to the semiconductor chip,
FIG. 4 is a diagram showing the relationship between the Vickers hardness of a metal electrode on a semiconductor and the failure rate due to repeated thermal fatigue of the semiconductor device. 1... Semiconductor chip, 2... External extraction electrode, 3... Glass sleeve, 4... Lead wire, 5
...Metal electrode of semiconductor chip, 6...Semiconductor.

Claims (1)

[Claims] 1. A semiconductor chip having a predetermined pn junction between a pair of main surfaces and having electrode films on each of the pair of main surfaces, a pair of electrodes respectively connected to the pair of electrode films, and a pair of electrodes and heating. Glued under;
In a glass sleeve type semiconductor device having a glass sleeve that clamps a semiconductor chip between a pair of electrodes, the hardness of at least one electrode film of the semiconductor chip is in the range of 20 to 50 in terms of hardness expressed by the Vickers method. A semiconductor device characterized by: