JPH11135534A - Semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a wire from being peeled off even of power on/off is repeated at the time of use by making the form of the crossing face of the connection part between the semiconductor chip and the wire in a semiconductor device in a form where a center is recessed. SOLUTION: Since ultrasonic vibration is transmitted to the connection part 2 for executing bonding by giving ultrasonic vibration in ultrasonic bonding, the wire is tightly suppressed by a wedge 3 and it is fixed. In such a case, the wedge 3 having the projecting form in the center of the tip is used. The wedge has the recessed parts at the ends and has the projecting form in the center. The wire is securely guided by the recessed parts at the ends and sound junction is realized. The center of the wire connection part 2a is recessed by the projecting form the center and the stress of an interface at the time of use is reduced. Thus, the connection part is prevented from being peeled off.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor device having a wire connection.

[0002]

2. Description of the Related Art In a conventional semiconductor device, a CC section of a connecting portion 2a of a wire 2 to a semiconductor chip 1 shown in FIG. 6 has a shape such that a central portion is convex as shown in FIG. Had. The reason why the center is convex is that the groove 3a is formed in the wedge 3 when performing bonding, as shown in FIG. The groove 3a is provided for positioning when holding down the wire 2 as shown in FIG. FIG. 8 is a sectional view taken along the line DD of FIG. A conventional apparatus of this type is disclosed in Japanese Patent Application Laid-Open No. 9-92672.

[0003]

In such a device, when the power is repeatedly turned on and off at the time of use, FIG.
As shown in FIG. 0, a crack 5 may develop between the wire connecting portion 2a and the chip 1 and peeling of the wire may occur. This has been a problem to be solved.

[0004]

The force acting on the interface between the wire and the semiconductor chip is reduced by making the cross-sectional shape of the connecting portion of the wire concave at the center, thereby preventing the wire from coming off. Thus, the above problem can be solved.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to the drawings. FIG. 2 shows a side view of a main part of a semiconductor device according to one embodiment of the present invention. FIG. 1 shows A in FIG.
3A shows a cross section. In FIG. 2, a wire 2 is connected to a semiconductor chip 1 at a connection portion 2a, and the cross section has a concave shape at the center as shown in FIG.

In the conventional device, the center of the connecting portion 2a is convex as shown in FIG. In this device, when the power is turned on and off repeatedly during use, the temperature rise and the temperature drop due to this heat generation are repeated, and the wire connection portion 2a
Temperature rises and falls repeatedly. Here, since the wire 2 is a metal having a large linear expansion coefficient and the chip 1 is made of a semiconductor material having a small linear expansion coefficient, a difference in thermal expansion occurs between the two. Therefore, as a result of performing a stress analysis on this structure, as shown in FIG.
It was found that a large stress 4 occurred at the interface. From this, it was found that this large interface stress 4 caused the interface crack 5 shown in FIG. 10 to grow and peeled off.

On the other hand, a stress analysis was also performed on the apparatus of this embodiment, and it was found that the generated stress was extremely small. As a result, peeling due to the growth of the interface crack was prevented.

In this embodiment, ultrasonic bonding is employed. In the case of thermocompression bonding, it is necessary to raise the temperature of the connection portion during bonding. On the other hand, by using ultrasonic bonding, the temperature does not need to be raised.
Damage can be reduced.

However, in the ultrasonic bonding, since the ultrasonic vibration is applied to perform the bonding, it is important that the wire 2 is firmly held down by the wedge 3 and fixed in order to transmit the ultrasonic vibration to the connecting portion 2a. For this reason, in the conventional apparatus, a wedge having a recess 3a for guiding the wire 2 is used, and the center of the cross section of the wire has a convex shape, thus causing the above-described problem.

In this embodiment, as shown in FIG.
A wedge 3 having a convex shape at the center of the tip is used. FIG. 4 shows a BB cross section of FIG. As shown in FIG. 4, the shape of the wedge 3 as viewed from the side of the tip has a concave shape at the end and a convex shape at the center. By using this wedge 3, the wire 2 was firmly guided by the recess at the end, and sound bonding was enabled, and the central portion of the wire connecting portion 2a was recessed by the central convex shape to reduce the stress at the interface during use. . By superimposing these effects, the reliability of the wire connection portion 2a can be increased.

[0011]

According to the apparatus of the present invention, the stress generated at the connecting portion of the wire can be reduced and the peeling of the connecting portion can be prevented.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing a state when wires are connected to a semiconductor chip according to an embodiment of the present invention.

FIG. 2 is a side sectional view showing a main part of FIG. 1;

FIG. 3 is a cross-sectional view showing a state at the time of bonding of the wire connection part of FIG. 2;

FIG. 4 is a side sectional view showing a state at the time of bonding of the wire connection portion of FIG. 3;

FIG. 5 is a diagram showing a cross section of a main part of a conventional device.

FIG. 6 is a view showing a side surface of a main part of a conventional device.

FIG. 7 is a cross-sectional view showing a state at the time of bonding of a wire connection part of a conventional device.

FIG. 8 is a side cross-sectional view showing a state at the time of bonding of a wire connection portion of a conventional device.

FIG. 9 is a diagram showing a generated stress of a conventional device.

FIG. 10 is a diagram showing crack propagation in a conventional device.

[Explanation of symbols]

1: semiconductor chip, 2: wire, 3: wedge, 4: generated stress, 5: crack.

Claims (1)

[Claims] 1. A semiconductor device having a connection portion of a wire to a semiconductor chip, wherein the cross section of the connection portion has a concave shape at the center.