JPS6322063B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the structure of a metal electrode for bonding provided on a metal wiring formed on a semiconductor element.

Semiconductor devices generally have a semiconductor element bonded onto a stem, and a metal electrode (hereinafter referred to as a bonding pad) made of aluminum provided on the element.
and the electrode terminal of the stem are connected with a lead wire made of gold (Au) or the like.

For the lead bonding between the bonding pad and the lead wire, thermocompression bonding of gold wire using the well-known nail head method is used. In this thermocompression bonding, the connection is made by heating the connection part and strongly pressing the Au lead wire against the aluminum (Al) bonding pad. In this case, dissimilar metals coexist in the bonding area, and when the temperature rises to a certain degree, intermetallic compounds are generated, and while the semiconductor device is in operation, these compounds progress from the surface to the bottom of the bonding area, and the underlying SiO ₂ reaching the layers. Since this compound layer is brittle, it has the disadvantage that the gold wire will peel off from the electrode even if a small force is applied.

The present invention eliminates the above drawbacks and
The bonding pad formed on SiO ₂ is
formed by an Al layer and a second Al layer, and the first and second
It is characterized by providing an upper layer with a predetermined shape to suppress the progress of intermetallic compounds between the aluminum layers, and this upper layer has a mesh-like or island-like Al ₂ O ₃ formed by oxidizing Al. form a layer. Note that forming a layer of Ti, Cr, Mo, etc. instead of the Al ₂ O ₃ inhibiting layer also has the same effect.

Hereinafter, one embodiment of the present invention in which Al ₂ O ₃ is formed in the inhibiting layer will be described with reference to FIGS. 1 to 3. In each figure, the same functional parts are given the same reference numerals and explained.

Figure 1 shows a cross section of the bonding pad part of a semiconductor device, where 1 is a Si substrate, 2 is a SiO ₂ layer,
3 is phosphor glass (PSG), 4 is the first Al layer, 5 is the second Al layer, 6 is the Au lead wire, 7 is the intermetallic compound (layer), and 8 is the metal made of reticulated Al ₂ O ₃ 1 shows an interlayer compound growth inhibiting layer.

To manufacture the bonding pad section having _the above structure, at the same time as the Al wiring shown in 9 of FIG. This is deposited to a thickness of μm, patterned, and then the entire surface of the semiconductor element is covered with a photoresist film. Only the network-shaped Al ₂ O ₃ forming portion of the bonding pad portion 20 is exposed to an opening, and the Al in the opening is exposed. A suppression layer made of Al ₂ O ₃ is formed by oxidation by a method such as anodic oxidation, plasma oxidation, oxygen ion implantation, or the like. The thickness of this Al ₂ O ₃ layer may be approximately 5000 Å. Thereafter, the resist film on the bonding pad portion 20 is removed and a second resist film is placed on the upper surface thereof.
An Al layer of approximately 1 to 1.5 μm is deposited, and then a PSG film 3 is deposited.
After that, thermocompression bonding of the Au lead wire 6 is performed to complete the semiconductor device. However, in a semiconductor device with such a configuration, there is no need for thermocompression bonding at the bonding pad portion of the semiconductor element or during operation of the semiconductor device. During the process, the temperature of the device increases and the intermetallic compound layer 7 advances toward the SiO ₂ layer 2 on the substrate side.
The Al ₂ O ₃ layer prevents the compound 7 from progressing, and the Al layer in the bonding pad portion 20
The intermetallic compound with Au lead wire 6 material (Au) is SiO ₂
The time it takes to reach the layer can be extended, and the life of the device can be extended.

FIG. 2 is a top view of FIG. 1, and numeral 9 indicates wiring led out from the electrodes of the semiconductor element, the upper surface of which is covered with a PSG film 3.

FIG. 3 shows the first bonding pad portion 20.
This is a top view showing a state in which an inhibition layer 8 made of a mesh-like Al ₂ O ₃ layer is formed on the Al layer 4, and 10 is a first Al
The layer 4 and the second Al layer 5 are connected to each other, and have electrical continuity at this portion.

Since this Al ₂ O ₃ suppression layer 8 is an insulator, the area of a typical bonding pad is 100 μm x 100 μm.
m, the area of the connecting part 10 in this part is reduced to 1/2 to 2/3, and the area of the suppression layer is reduced to 1/2 to 1/3 to ensure sufficient electrical continuity of the electrode part. The structure has the effect of inhibiting the progress of intermetallic compounds.

By configuring the bonding pad portion as described above, the reliability of the semiconductor device can be greatly improved.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the bonding pad portion of a semiconductor element, FIG. 2 is a top view of FIG. 1, and FIG.
A top view showing a state in which a suppression layer 8 made of Al ₂ O ₃ is formed, 1: Si substrate, 2: SiO ₂ layer, 3: PSG film,
4: First Al layer, 5: Second Al layer, 6: Au lead wire, 7: Intermetallic compound, 8: Inhibition layer made of Al ₂ O ₃ , 9: Wiring, 10: First and second 20: Bonding pad portion.

Claims (1)

[Claims] 1. In a semiconductor device comprising a metal electrode for bonding a lead wire to a metal wiring portion provided in a semiconductor element, the metal electrode is composed of a first aluminum layer and a second aluminum layer, and the first and second A semiconductor device characterized in that a mesh-shaped alloy growth inhibiting layer is formed between the aluminum layers to inhibit the growth of an alloy of the lead wire and aluminum.