JPH0582581A - Manufacture of semiconductor device - Google Patents

Abstract

(57) [Summary] [Purpose] Regarding the method of preventing corrosion of aluminum pads,
The purpose is to prevent pad corrosion and improve device reliability. [Structure] 1) An exposed portion of a bonding pad made of an aluminum (Al) -based metal film formed on a semiconductor chip is covered with a gold (Au) film. 2) Wire bonding is performed on the bonding pad made of an aluminum (Al) -based metal film formed on the semiconductor chip, and then gold (Au) is applied to the exposed portion of the bonding pad.
It is configured to cover a film or an alumina (Al ₂ O ₃ ) film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for preventing corrosion of aluminum (Al) pads.

In a general semiconductor device in a plastic package, it is known that outside air enters the internal semiconductor chip through the package. For this reason,
There is a phenomenon of pad corrosion, in which a device failure due to humidity occurs and metal wiring in the pad part corrodes, and countermeasures are required.

[0003]

2. Description of the Related Art The above-mentioned pad corrosion occurs in a sealing method using a resin mold which is directly mounted on a substrate, a film or the like without using a semiconductor device of a plastic package or a package.

The reason for this is that the conventional pad has a cover insulating film coated on the periphery of the pad and is led out from the pad by ball bonding of a gold (Au) wire or the like. This is because the moisture that has entered from the outside acts on it.

When the above-mentioned ball bonding using Au wire is used to prevent pad corrosion, Al is less likely to be corroded due to the alloying of Au and Al due to heating during bonding, but the effect is not sufficient. Was not.

[0006]

In the prior art example, pad corrosion causes a disconnection failure, which lowers the reliability of the device.

It is an object of the present invention to prevent pad corrosion and improve device reliability.

[0008]

[Means for Solving the Problems] 1)
A method of manufacturing a semiconductor device in which an exposed portion of a bonding pad made of an aluminum (Al) -based metal film formed on a semiconductor chip is covered with a gold (Au) film, or 2) aluminum (Al) formed on a semiconductor chip This is achieved by a method of manufacturing a semiconductor device in which wire bonding is performed on a bonding pad made of a system metal film and then an exposed portion of the bonding pad is covered with a gold (Au) film or an alumina (Al ₂ O ₃ ) film.

[0009]

In order to prevent Al from being corroded by moisture, the present invention provides Au with a small ionization tendency in the contact window of the pad.
By coating with a film or an alumina (Al ₂ O ₃ ) film, the moisture resistance is improved.

The means for achieving this are as follows. (1) The uppermost metal wiring film has a two-layer structure of Al + Au. (2) After patterning the uppermost metal wiring film, Au plating is performed. (3) After opening the pad window, apply Au plating. (4) After wire bonding on the pad, apply Au plating.

Instead of the Au plating described in (2), (3) and (4) above, selective growth by vapor phase epitaxy (CVD) may be performed. (5) After wire bonding on the pad, the exposed part of the pad is covered with an Al ₂ O ₃ film by an anodic oxidation method or the like.

[0012]

EXAMPLE 1 FIGS. 1A to 1E are sectional views for explaining Example 1 of the present invention. In Figure 1 (A), silicon (Si) substrate
11 Al film 1A having a thickness of 1 μm as the uppermost wiring film, and by sputtering or vapor deposition or the CVD method on it.
The Au film 1B having a thickness of 100 to 5000Å is applied.

In FIG. 1B, the wiring film including the pad portion is patterned. In FIG. 1C, a two-layer film of a silicon dioxide (SiO ₂ ) film and a silicon nitride (Si ₃ N ₄ ) film is deposited as the cover insulating film 2 by the CVD method.

In FIG. 1D, a window for bonding is opened in the cover insulating film 2. In Fig. 1 (E), wire bonding is performed on the pad. This bonding example is Au
It is ball bonding of wires. In the figure, 3 is an Au ball and 4 is an Au wire.

FIG. 2 is a sectional view for explaining the second embodiment of the present invention. In this embodiment, only the Al film 1A is deposited as the uppermost wiring film, and after this film is patterned, Au plating or CVD Au selective growth is performed on the Al film 1A to obtain a thickness of 100 to 5000Å.
The Au film 1B is formed.

Here, an example of the selective growth condition of CVD Au is as follows. Reactive gas: (Dimethyl 1,1,1 trifluoro 2,4 pentadionade) Gold Gas pressure: 10 mTorr Substrate temperature: 150 ° C RF power: 0.2 W / cm ² After this, see Figures 1 (C) to (E). It is the same.

FIG. 3 is a sectional view for explaining the third embodiment of the present invention. Also in this embodiment, only the Al film 1A is deposited as the uppermost wiring film, the insulating film 2 is deposited after patterning this film, the contact window is opened, and then Au plating or CVD Au is formed on the Al film 1A. By selective growth of 100-5000 Å thick Au film
Form 1B.

After that, wire bonding is performed. Figure 4
(A)-(E) is sectional drawing explaining Example 4 of this invention. In FIG. 4A, an Al film 1A having a thickness of 1 μm is deposited on the Si substrate 11 as the uppermost wiring film.

In FIG. 4B, the wiring film including the pad portion is patterned. In FIG. 4 (C), a two-layer film of SiO ₂ film and Si ₃ N ₄ film is deposited as the cover insulating film 2 by the CVD method.

Next, a window for bonding is opened in the cover insulating film 2. Wire bonding is performed on the pad as shown in FIG. This bonding example is Au ball bonding, 3 is an Au ball, and 4 is an Au wire.

In FIG. 4 (E), an Au plating film (or CVD Au film) 5 is formed on the pad. At this time, the exposed portion of the Al pad is covered with the Au plating film 4. FIG. 5 is a sectional view illustrating a fifth embodiment of the present invention.

After completion of wire bonding, the exposed portion of the Al pad is anodized to form an Al ₂ O ₃ film 6 on the Al surface. An example of anodizing conditions is shown below.

Electrolyte: Aqueous oxalic acid solution Voltage: 20 V Cathode: Chamber inner wall (ground) Temperature: 20 ° C. In the embodiment, Au ball bonding is used.
Other bonding may be used.

The present invention is also applicable when the chip is covered with polyimide.

[0025]

According to the present invention, pad corrosion can be prevented and the device reliability can be improved.

[Brief description of drawings]

FIG. 1 is a sectional view illustrating a first embodiment of the present invention.

FIG. 2 is a sectional view illustrating a second embodiment of the present invention.

FIG. 3 is a sectional view illustrating a third embodiment of the present invention.

FIG. 4 is a sectional view illustrating a fourth embodiment of the present invention.

FIG. 5 is a sectional view illustrating a fifth embodiment of the present invention.

[Explanation of symbols]

11 Semiconductor substrate Si substrate 1A Uppermost wiring film Al film 1B Al film 1A Au film covering 2 A Cover insulating film 3 Au ball 4 Au wire 5 Au plating film (or CVD Au film) 6 Al ₂ O ₃ film

Claims (2)

[Claims] 1. A method of manufacturing a semiconductor device, wherein an exposed portion of a bonding pad made of an aluminum (Al) -based metal film formed on a semiconductor chip is covered with a gold (Au) film. 2. A wire bonding is performed on a bonding pad made of an aluminum (Al) -based metal film formed on a semiconductor chip, and then a gold (Au) film or an alumina (Al ₂ O ₃ ) film is formed on an exposed portion of the bonding pad. A method for manufacturing a semiconductor device, comprising: