JPS59150427A - Semiconductor device and manufacture of the same - Google Patents

Abstract

PURPOSE:To sufficiently protect the wiring layer consisting of aluminium or aluminium alloy from contamination and also prevent corrosion and its elution by forming an aluminium fluoride film on the surface of metal wiring layer consisting of aluminium or aluminium alloy formed on wafer as a contamination preventing film. CONSTITUTION:Wafers 10 are placed in a gas plasma apparatus and the fleon gas is then introduced thereto. Through reaction of fluorine radical and a metal wiring layer 4, a fluoride film 6 of aluminium or aluminium alloy is formed on the surface of metal wiring layer 4 in the thickness of about 100-1,000Angstrom . Thereafter, a protection film 5 consisting of silicon nitride film, etc. is deposited on the wafers 10. Thereafter, the protection film 5 on the bonding pad is selectively eliminated. The fluoride film of aluminium or aluminium alloy on the bonding pad can be eliminated by adequately heating the wafers with water.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a semiconductor device using aluminum and its alloy as a wiring material, and a method for manufacturing the same.

[Technical background of the invention]

Currently, aluminum A is used as a wiring material in various semiconductor devices.
A and aluminum alloys are often used. These aluminum and its alloys easily react with acids, alkalis, etc. and corrode and elute, so some kind of countermeasure is required.

Therefore, in order to prevent acid ions, alkali metals, etc. from adhering to aluminum or aluminum alloys from the outside, as shown in FIG. Then, a protective film 5 made of silicon oxide, silicon nitride, or the like is formed. This protective film 5 has the function of preventing most of the external contaminants from passing through or being trapped in the film, thereby preventing them from reaching the inside of the semiconductor wafer. In FIG. 1, 1 is a semiconductor substrate, 2 is a diffusion layer,
3 is an oxide film, and 4 is a metal wiring layer made of aluminum or aluminum alloy.

[Problems with background technology]

The conventional protective film described above is effective against external contamination after the protective film is formed by preventing it from sticking to the surface of the semiconductor wafer. It has no effect on contaminants attached to the surface. For example, many chemicals or gases are used when photographically engraving layers made of aluminum or its alloys, but these chemicals or gases are not removed sufficiently and remain on the semiconductor wafer, resulting in a subsequent protective film. Even if the aluminum or aluminum alloy layer is formed on a wafer, it often causes deterioration such as corrosion or elution of the aluminum or aluminum alloy layer.

Furthermore, even a protective film is not perfect, and there are minute pinholes, etc., and water and contaminants that enter through these holes can cause deterioration of the aluminum or aluminum alloy wiring layer.

Furthermore, if a silicon oxide film containing added impurities such as phosphorus is used as a protective film, if the concentration is incorrectly controlled and a high concentration of impurities enters, the impurities themselves may cause deterioration of aluminum or aluminum alloys. Become. On the other hand, if the concentration of added impurities is too low, the effect of trapping external contaminants in the protective film will be reduced.

[Purpose of the invention]

The present invention has been made in view of the above points, and its purpose is not only to prevent contamination from the outside of the protective film formed on the semiconductor urchin/...-L, but also to prevent contamination of the semiconductor before the protective film is formed. To provide a semiconductor device that is sufficiently protected against contamination caused by surface contamination and added impurities in a protective film, and in which corrosion and elution of wiring layers made of aluminum and aluminum alloys are prevented. Also, upper h1;
An object of the present invention is to provide a method for manufacturing a semiconductor device that can efficiently manufacture a semiconductor device such as the one described above.

[A essential point of the invention]

By the way, when aluminum or aluminum alloy is subjected to high-temperature heat treatment, abnormal growth parts of aluminum such as hillocks are formed, and for example, PSG is formed on this aluminum layer.
It is known that when a protective Bt film or the like is formed, problems such as deterioration of the adhesion of the protective film and generation of pinholes occur.

In addition, moisture and chemicals remaining on the aluminum can easily cause corrosion of the aluminum, and even if contaminants stick to the aluminum wiring, if there is no moisture, the aluminum will corrode.
p1tillI is difficult to progress.

From the above points, the semiconductor device IIV'i according to the present invention
In this case, as a contamination prevention film, a dense aluminum fluoride film is formed on the surface of a metal wiring layer made of aluminum or aluminum alloy formed on a semiconductor wafer.

In addition, in the method for manufacturing a semiconductor device according to the invention, in order to form the above-described dense aluminum fluoride shell with good adhesion, a wafer having a metal wiring layer made of aluminum or an alloy thereof formed on the upper surface is used. The metal wiring layer surface is fluorinated in a dry atmosphere to form a fluoride film of aluminum or its alloy.

[Embodiments of the invention]

An embodiment of the present invention will be described and explained below with reference to the drawings.

In FIG. 2, a layer made of aluminum or an alloy thereof is deposited on a semiconductor substrate 1 on which a predetermined diffusion layer 2, oxide M3, etc. have been formed. Thereafter, the metal layer is photographically chained in a predetermined pattern to form a metal wiring layer 4 including bonding pads. Ueno 1 like this
First, θ is set in the gas chamber of the gas plasma apparatus, and Freon gas (CF4) is introduced into the gas chamber. Then, for example, by using high-frequency power, the fluorine F contained in the Freon gas is converted into highly reactive fluorine radicals, and the fluorine radicals are reacted with the metal wiring layer 4 to coat the surface of the metal wiring layer 4 with aluminum or its alloy. 'A tsulfide film 6 is formed to a thickness of 100 to 1000X. In addition,
The formation of the above-mentioned fluoride 6 is carried out at room temperature.

Thereafter, a protective film 5 made of, for example, a silicon oxide film, a PSG film, or a silicon nitride film is deposited on the semiconductor layer 10. Next, the protective film 5 on the denting mud is selectively removed.

Note that the fluoride film of aluminum or aluminum alloy on the bonding pad may reduce bonding properties, so the protective film 5 on the bonding pad may be
After removing the fluoride, the fluoride film on the bonding layer is removed by heating the fluoride with appropriate water.

However, the fluoride film 6 formed on the metal wiring layer j as in step 2 has a very dense structure, and the impurities contained in the protective film 5 are made of metal made of aluminum or aluminum alloy. This prevents it from reaching the wiring layer 4. Of course, the protective film 5 and the fluoride film 6 double protect the metal wiring layer 4 against contamination from the outside of the protective film 5, which is effective.

In addition, in the above-described step of forming the fluoride film 6, the metal wiring layer 4
Since the fluorination treatment is performed in a dry atmosphere without using liquid chemicals, no moisture remains on the surface of Ueno-10. Therefore, the corrosive action of contaminants adhering to the surface of the metal wiring layer 4 can be prevented. Furthermore, by coating the surface of the metal wiring M4 with a fluoride film, contaminants adhering to the surface of the metal wiring layer 4 can be fixed, which is effective.

However, when performing plasma conversion treatment, Freon (CF)
4) As mentioned above, when gas is used as the introduced gas,
This gas can be used as long as it can generate fluorine radicals and there is no risk that the resulting gas will chemically etch aluminum or silicon, such as FS6.
Gas may also be used.

In addition to the method described above, in which the surface of the metal wiring layer is fluorinated using fluorine plasma at room temperature, a fluoride film of aluminum or its alloy can be formed by the following method. That is, fluorine atoms are implanted into the surface of the metal wiring layer in a dry atmosphere, and then the wafer is heated to a temperature below the recrystallization temperature (usually 350 to 400°C) of the aluminum or aluminum alloy that is the material for the metal wiring layer. The aluminum in the metal wiring layer is reacted with fluorine to form a fluoride film.

〔Effect of the invention〕

Figure 3 shows a wafer with a fluoride film formed by the plasma method described above, observed with an optical microscope, and shows abnormalities in the N411 layer made of aluminum or its alloy.
The incidence of alteration is shown as a relative value between the thickness of the fluoride film formed by the plasma method and the case without the fluoride film. As is clear from this figure, the surface of the metal wiring layer is
By fluoridating with a film thickness of 0X to 1oooX,
Abnormalities and deterioration can be reduced to 1/3 to 1/4.

As described above, according to the present invention, an aluminum heptadide film is formed on the metal wiring layer, which has a sufficient ability to prevent not only contamination from the outside of the protective film but also contamination caused by impurities in the protective film. It is possible to provide a semiconductor device in which the metal wiring layer is formed, and corrosion and elution of the metal wiring layer can be prevented.

According to the method for manufacturing a semiconductor device according to the present invention,
A fluoride film can be efficiently formed on a metal wiring layer made of aluminum or its alloy as described above, and since fluoride is carried out in a dry atmosphere, water that promotes the corrosion of contaminants can be removed, making it possible to form a fluoride film on metal wiring layers made of aluminum or its alloys. Corrosion and elution of the layer can be effectively prevented.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an example of a conventional semiconductor device, FIG. 2 is a sectional view illustrating an embodiment of the present invention, and FIG. 3 shows the incidence of abnormality and deterioration of wiring layers in the device according to the invention. This is a graph showing. 4... Metal wiring layer, 5... Capacitive film, 6... Fluoride film. Applicant's representative Patent attorney Takehiko Suzue 1 illustration, 2 illustrations

Claims (4)

[Claims] (1) Surface made of aluminum or its alloy
A semiconductor device having an I layer, characterized in that a fluoride film of aluminum or an alloy thereof is formed on the surface of the wiring layer. (2) The surface of a wiring layer formed on a semiconductor wafer made of aluminum or its alloy is fluorinated in a dry atmosphere below the recrystallization temperature of the wiring layer material, and the surface of the wiring layer is coated with aluminum or aluminum. A method for manufacturing a semiconductor device, comprising forming a fluoride film of the alloy. (3) The method for manufacturing a semiconductor device according to claim 2, wherein the fluorination treatment is a plasma fluorination treatment. (4) As the fluorination treatment, the element atoms are
Claim 2, characterized in that after ion implantation into the surface of the wiring layer, heat treatment is performed at a degree of recrystallization below that of the wiring layer.
A method for manufacturing a semiconductor device according to section 1.