JPH0472732A - Semiconductor device - Google Patents

Abstract

PURPOSE:To avert the unfavorable effect on the wire bonding properties by a method wherein the two layer structured Al wiring film wherein the Si, Cu concentration in the second Al film as the upper layer is lower than that in the first Al film as the lower layer is used. CONSTITUTION:An NSG film about 8000Angstrom thick as an interlayer insulating film 2 is deposited by e.g. LP-CVD process on an Si substrate l. Next, an Al-Si- Cu film containing Si, Cu is sputter-evaporated as the first A film. Furthermore, another Althermore, another Al film in the lower Cu, an that in the first Al film or not containing Si, Cu is sputter-evaporated as the second Al film 4. Next, the two layer structured Al wiring film 6 comprising Al/Si-Cu thus formed is patterned using drywet process to be further heat-treated. Next, e.g. a plasma SiN film is deposited as a surface protective film 5 to be sintered. Furthermore, the Al film 4 as the upper layer out of the Al wiring film 6 is patterned by dryetching process so as to expose the surface of the Al film 4.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a semiconductor device, and in particular to an AI
Related to wiring structure.

[Conventional technology]

An example of a conventional semiconductor device is shown in FIG. 2 as a cross-sectional structural diagram of a bonding pane. In this semiconductor device, an NSG film is grown as a glabellar insulating film 2 on a Si substrate 1. Further, on top of that, as a wiring film, Al-3i-C containing 1 wt% of St and 0.5 wt% of Cu is formed.
The U film 3 is smoked to a thickness of 1 μm. Furthermore, a plasma SiN film is grown as a surface protection film 5, and the bonding pad 2 is etched away to expose the surface of the Al-3i-Cu film 3, which is the wafer A film.

[Problem to be solved by the invention]

In the case of a conventional semiconductor device, the sintering process after the deposition of the Aj-3i-Cu film 3 causes Si and Cu to move to the surface side, resulting in a problem in that the adhesion of wire bonds deteriorates.

In other words, the A of the Al-3i-Cu film 3 alone as in the conventional example
In the case of a wiring film, when Si and Cu move to the surface during the heat treatment process, the concentration may become twice as high as that in the case of uniform distribution of 5ib on the surface side.

Since the Al wiring film containing Si or Cu generally has higher hardness than the pure Al film 4, it will not adhere unless the power conditions during wire bonding are strict.

Increasing the power increases the impact on the chip, increasing the possibility of cranking (Also, the Al film with a high concentration of Si and Cu has poor adhesion to the Au wire.

[Means to solve the problem]

The semiconductor device of the present invention uses Cu as the wiring film.

On the first Al film containing Si impurities, Cu, S,
A with a two-layer structure in which a second Al film is laminated with a temperature of 71 degrees lower than that of the first An film (which may not contain Cu or Si at all).
1 wiring film is used.

[For production]

According to the configuration of this invention, the first
And the second Al film is made of a second Al film with a low degree of Cu and Si.
Since the AJ wiring film has a two-layer structure with the n film as the upper layer, Si
Even if Si and Cu move onto the surface of the Al wiring film, the concentration of Si and Cu on the surface of the Al wiring film can be maintained lower than in the past, and the influence on the adhesion of the wire pond is reduced.

〔Example〕

An embodiment of the semiconductor device of the present invention is shown in FIG. 1 as a cross-sectional structural diagram of a bonding pad portion.

In this semiconductor device, an NSC film is grown as an interlayer insulating film 2 on a Si substrate 1 to a thickness of approximately 8000 nm by, for example, the LP-CVD method. Next, an Al5i-Cu film 3 containing 1 wt % of Sl and 5 wt % of Cu is sputter-deposited as a first An film to a thickness of about 8,000 mm. Furthermore, an Al film 4 containing no Si or Cu is sputter-deposited as a second Al film to a thickness of approximately 2000 mm.

After forming the Al wiring film 6 having a two-layer structure of Al/Al-3i-Cu in this manner, the Al wiring film 6 is buttered by a dry wet method. Furthermore, heat treatment is performed at 450° C. for about 30 minutes as a sintering treatment.

Next, as the surface protection film 5, for example, a plasma SiN film is grown to a thickness of about 8,000 nm at 380°C.

Perform sintering for about 30 minutes. Furthermore, in order to expose the surface of the upper Al film 4 of the Al wiring film 6 in the bonding pad portion, patterning is performed by dry etching.

In the case of this embodiment, after the deposition of the Al film 4 and the surface protective film 5.
There is a heat treatment step after the growth of the AJ-3i-Cu film 3, and in these heat treatment steps, Si and Cu in the AJ-3i-Cu film 3 move to the surface side, that is, into the 1M film of the kl-3i-Cu film 3. .

However, if the Al wiring film 6 has a two-layer structure as in this embodiment, and the Si and Cu concentrations on the surface side are set to 0, the heat treatment will reduce the concentration of Si and Cu in the lower layer Ajl-5i-Cu film 3. S
i, Even if Cu moves to the surface side, S in the upper layer of the AI film
i and Cu11 degrees are 0.5wt% and 0.2wt, respectively.
%, lower concentration than in the conventional case can be maintained, and the effect on wire bonding properties is small.

In the above example, a two-layer structure of AI/Al-3i-Cu was shown.
Like an Al wiring film in which the upper layer is an An-3iCu film containing 1 wt% Si, Q Q, and 5 wt% gold, the Si, C of the second An film in the upper layer is
The first A with a lower ufi degree! It is effective as long as it is lower than the Si and Cufi degrees of the film.

According to the semiconductor device of the present invention, the concentration of Si and Cu in the second Al film in the upper layer is lower than the concentration of Si and Cu in the first Al film in the lower layer.
Since we use a two-layered Al wiring film with a lower concentration than Therefore, an adverse effect on wire bonding properties can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a structural cross-sectional view of a bonding pad portion of a semiconductor device according to an embodiment of the present invention, and FIG. 2 is a structural cross-sectional view of a bonding pad portion of a conventional semiconductor device. DESCRIPTION OF SYMBOLS 1...Si substrate, 2...Interlayer insulating film, 3...A7
Film-3i-Cu film, 4... Afll, 5... Surface protective film, 6... Al wiring film [Effects of the invention]

Claims (1)

[Claims] It is characterized by using an Al wiring film having a two-layer structure in which a second Al film having a lower Cu and Si concentration than the first Al film is laminated on a first Al film containing impurities of Cu and Si. semiconductor devices.