JPS6227734B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a structure of a semiconductor device, and particularly to a structure of a semiconductor device in which the area under a bonding electrode is not destroyed during a bonding process.

The element patterns of recent high-frequency bipolar transistors have been extremely miniaturized to increase the figure of merit. As a result, the width of the metal electrode covering the emitter and base contact windows has become narrower, resulting in significantly poor water resistance and poor DC amplification and noise figure. In order to compensate for this deterioration in water resistance, a structure has been adopted in which the entire surface of the pellet is covered with a silicon nitride film using an anodic oxidation method.

However, in the assembly process, labor savings have progressed and bonding has become faster, but this pellet structure has caused problems such as the silicon under the bonding electrode peeling off due to impact force during bonding.

An object of the present invention is to provide a high-frequency transistor structure suitable for high-speed bonding.

According to the present invention, a semiconductor device is obtained in which a buffer layer made of a relatively soft insulator is provided between an electrode pad and a semiconductor substrate.

The present invention will be explained in more detail below using the drawings. Figures 1a to 1c illustrate conventional semiconductor devices and their drawbacks. Figure 1a shows a semiconductor element formed by anodizing the entire surface of a surface oxide film 2 of a semiconductor substrate 1 formed by impurity diffusion. 1 is a cross-sectional view of a conventional semiconductor device in which a silicon nitride film 3 with a thickness of about 300 Å is formed, and then a bonding electrode 4 is formed. FIG. 1b shows that by bonding the bonding electrode 4 with a gold wire 5, a bonding impact force 6 is applied to the bonding electrode 4, the silicon nitride film 3, the silicon oxide film 2, and the semiconductor substrate 1, and a strain 6' is caused to these. FIG. Due to such a bonding impact force 6, the silicon nitride film 3, the silicon oxide film 2, and the semiconductor substrate 1 are separated as shown in FIG. 1c, and a hole 7 is formed. It is presumed that the reason why such peeling occurs is that the silicon nitride film 3 is very thin and has a very weak ability to buffer the bonding impact force 6, and the stress is directly concentrated under the bonding electrode 4. Ru.

According to one embodiment of the present invention, as shown in FIG. 2, a silicon oxide film 12 is covered on a silicon substrate 11 on which a semiconductor element is formed by impurity diffusion, and an electrode extraction portion from a diffusion region is covered with a silicon oxide film 12. Provide an opening,
A metal wiring electrode 15 is led out from here, and a bonding electrode 1 is formed on the silicon oxide film 12.
A silicon nitride film 18 with a thickness of 1,000 to 1,500 Å is provided on the portion where 4 is provided, and a silicon nitride film 13 is provided on the entire surface, and then a bonding electrode 14 of, for example, gold or aluminum is provided.

When a thin gold wire is bonded to this bonding electrode 14, the bonding impact force is buffered by the relatively soft and thick silicon nitride film 18 and is not applied to the underlying silicon oxide film 12 or silicon substrate 11. As described above, according to the semiconductor device having the structure shown in FIG. 2, the peeling defect rate can be improved from 5% to 0.1% by using the silicon nitride film 18 as a buffer layer. Therefore, even if it is unavoidable to increase the bonding impact force, by providing a buffer layer, safe and reliable bonding work can be performed.

Note that the silicon nitride film 18 as a buffer layer is
If it is at least under the bonding electrode 14,
Although it may be present in other parts, the silicon oxide film 12
If the insulating film is provided around the opening, the overall thickness of the insulating film becomes too thick, making it difficult to take out the wiring metal without breaking the wire. Also, since metal is relatively soft, it is suitable as a buffer layer, but it has a large stray capacitance, so care must be taken when using it.

[Brief explanation of the drawing]

FIGS. 1a to 1c are cross-sectional views showing the structure and delamination of a conventional semiconductor device. FIG. 2 is a sectional view showing an embodiment of the present invention with a buffer layer. 1, 11... Silicon substrate, 2, 12... Silicon oxide film, 3, 13... Silicon nitride film, 4,
14... Bonding electrode, 5... Bonding wire, 6... Bonding impact force, 6'...
Bonding distortion, 7...Peeled part, 15...
...Wiring electrode, 18...Buffer layer (silicon nitride film).

Claims (1)

[Claims] 1. An insulating layer covering a semiconductor substrate and having a contact hole; a buffer layer made of an inorganic insulating material selectively formed on the insulating layer; and a buffer layer covering the surface of the buffer layer and the insulating layer and extending to the contact hole. a silicon nitride film formed, a bonding electrode formed on the silicon nitride film covering the buffer layer, and a bonding electrode formed extending on the silicon nitride film and contacting a part of the semiconductor substrate through the contact hole. A semiconductor device including an electrode wiring layer.