JPH0590193A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To contrive a reduction in a contact resistance and the stabilization of the contact resistance by a method wherein in the case where a silicon- containing aluminum alloy wiring is formed, the epitaxial growth of a silicon film, which is generated on a silicon substrate in a contact hole, is prevented from being generated. CONSTITUTION:A BPSG film or an insulating film 13, such as a PSG film, formed on a silicon substrate 11 is selectivery etched using a photoresist as a mask to make a contact hole 14. After the substrate 11 in the hole 14 is subjected to HF cleaning and a natural oxide film or the like is previously removed, a cleaning treatment using SC1 to SC2 is performed to form a silicon oxide film 15 on the surface of the substrate 11 and after that, a silicon- containing aluminum alloy wiring 16 is formed on the film 15.

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 prevent epitaxial growth of silicon in a contact hole of a semiconductor device provided with an aluminum alloy wiring containing silicon to reduce and stabilize the contact resistance. The present invention relates to a method for manufacturing a semiconductor device.

[0002]

2. Description of the Related Art FIG. 2 is a sectional view showing a conventional method for manufacturing a semiconductor device. First, as shown in FIG. 2A, the surface of the silicon substrate (1) is doped with impurities to form a diffusion layer (2), and then BP is formed on the silicon substrate (1).
An insulating film (3) such as an SG film or a PSG film is formed by the CVD method, and then the insulating film (3) is selectively removed by etching using a photoresist as a mask to form a contact hole (4). ..

Then, as shown in FIG. 2B, the surface of the silicon substrate (1) in the contact hole (4) is cleaned with HF (cleaning with hydrofluoric acid diluted with pure water) and adhered to the surface. Remove the natural oxide film, etc.
An aluminum alloy wiring (5) containing 2% is formed by using a sputtering method or the like. Subsequently, heat treatment is performed at 400 ° C. to 450 ° C. to obtain ohmic contact between the diffusion layer (3) and the aluminum alloy wiring (5), and thereafter, a silicon nitride film is formed on the aluminum alloy wiring (5). Etc., a protective film is formed, and the protective film is annealed. During these heat treatments, as shown in FIG. 2C, the silicon contained in the aluminum alloy wiring (5) is precipitated in the wiring (5) and the silicon of the contact hole (4) is also deposited. Epitaxial growth of silicon occurs on the surface of the substrate (1) to form a deposit covering the whole or a part of the contact hole (4). In the figure, (6) indicates an epitaxial growth layer.

[0004]

As described above, according to the conventional method, the silicon substrate (1) of the contact hole (4) is cleaned with HF to remove the natural oxide film and the like, and thus the silicon substrate (1) of the substrate (1) is removed. Since the surface was exposed and the aluminum alloy wiring (5) containing silicon was formed on it, silicon was deposited by the subsequent heat treatment, and the surface of the diffusion layer (2) of the contact hole (4) was covered with silicon. There was a problem that the contact resistance was increased by being covered with the epitaxial growth layer (6).

The present invention has been made in view of the above conventional problems, and it is a method of manufacturing a semiconductor device in which the epitaxial growth of silicon in the contact hole (4) is prevented and the contact resistance is reduced and stabilized. Is intended to provide.

[0006]

According to the present invention, an insulating film (13) such as a BPSG film or a PSG film formed on a silicon substrate (11) is selectively etched using a photoresist as a mask to form a contact hole ( 14) is formed, the silicon substrate (11) in the contact hole (14) is subjected to HF cleaning to remove a natural oxide film and the like in advance, and then SC1 or SC2 cleaning treatment is applied to the surface of the silicon substrate (11). Then, a thin silicon oxide film (15) is formed on the thin silicon oxide film (15), and then an aluminum alloy wiring (16) containing silicon is formed on the thin silicon oxide film (15).

[0007]

According to the above-mentioned means, the silicon substrate (11)
Since the surface of is covered with a thin silicon oxide film (15) formed by the oxidizing action of hydrogen peroxide (H ₂ O ₂ ) contained in the SC1 cleaning liquid and the SC2 cleaning liquid, epitaxial growth of silicon does not occur.

Further, in the SC1 cleaning, the etching action of the silicon surface by ammonium hydroxide (NH ₄ OH) contained in the cleaning liquid, and in the SC2 cleaning, the removal of heavy metal of hydrogen chloride (HCl) contained in the cleaning liquid. By the action, it becomes possible to form a high-quality thin oxide film (15) with few defects, and it is possible to reliably prevent the epitaxial growth of silicon.

[0009]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a cross-sectional view showing a method for manufacturing a semiconductor device of the present invention. First, as shown in FIG. 1A, a diffusion layer (12) is formed by doping impurities such as phosphorus and boron on the surface of a silicon substrate (11) as in a conventional method, and then the silicon substrate (11) is formed. ), An insulating film (13) such as a BPSG film or a PSG film is formed by a CVD method, and then the insulating film (13) is selectively removed by etching using a photoresist as a mask to remove the diffusion layer (12). ), A contact hole (14) is formed thereon.

Then, HF cleaning is performed in order to remove the natural oxide film formed on the diffusion layer (12) or the oxide film attached by the reflow heat treatment of the insulating film (13). Then, SC1 cleaning treatment (cleaning treatment with a mixed solution of H ₂ O ₂ , NH ₄ OH and H ₂ O having a predetermined mixing ratio) or SC2 cleaning treatment (mixing of H ₂ O ₂ , HCl and H ₂ O having a predetermined mixing ratio). Then, a thin silicon oxide film (15) of about 10 Å is formed on the surface of the silicon substrate (11) as shown in FIG. 1B. The thin silicon oxide film (15) is formed by the cleaning treatment mainly due to the oxidizing action of hydrogen peroxide (H ₂ O ₂ ), and its growth rate depends on the mixing ratio of pure water (H ₂ O). Controlled. Furthermore, in SC1 cleaning, the silicon etching action of ammonium hydroxide (NH ₄ OH), S
In C2 cleaning, Fe contained in hydrogen chloride (HCl),
Silicon substrate (11) by removing heavy metals such as Cu
The surface is cleaned, and a thin silicon oxide film of good quality is uniformly formed.

In addition, in order to form the thin oxide film (15), a method of leaving it in the air or immersing it in warm water may be considered. However, these have drawbacks such as difficulty in controlling the film thickness and risk of contamination by foreign matter. After this, as shown in FIG. 1C, an aluminum alloy wiring (16) containing 1 to 2% of silicon is formed by a sputtering method or the like. Here, a polysilicon layer of 100 Å to 1000 Å may be provided under the aluminum alloy wiring (16) in order to enhance the effect of preventing silicon deposition in the contact hole.

Thus, according to the present invention, the diffusion layer (12)
A thin silicon oxide film (15) is formed between the aluminum alloy wiring (16) and the aluminum alloy wiring (16) so that the conduction is not substantially affected. Epitaxial growth of silicon is prevented, and contact resistance can be reduced and stabilized.

[0013]

As described above, according to the present invention,
The surface of the silicon substrate (11) has a thin silicon oxide film (1
Since it is covered with 5), the epitaxial growth of silicon in the contact hole (14) is prevented, and the contact resistance can be reduced.

Further, according to the present invention, since a high-quality thin silicon oxide film (15) having no defects is formed, there is no possibility of epitaxial growth of silicon from such a defective portion, and the contact resistance is reduced and its variation is reduced. Also has the effect of reducing

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a method of manufacturing a semiconductor device according to an embodiment of the invention.

FIG. 2 is a cross-sectional view showing a method of manufacturing a semiconductor device according to a conventional example.

Claims (2)

[Claims] 1. A step of selectively etching an insulating film formed on a silicon substrate to form a contact hole, and a step of subjecting the silicon substrate of the contact hole to HF cleaning treatment and SC1 cleaning treatment in sequence to obtain the contact hole. A semiconductor comprising a step of forming a thin silicon oxide film on the surface of a silicon substrate for preventing epitaxial growth of silicon, and a step of forming an aluminum alloy wiring containing silicon on the thin silicon oxide film. Device manufacturing method. 2. A step of selectively etching an insulating film formed on a silicon substrate to form a contact hole, and an HF cleaning process and an SC2 cleaning process being sequentially performed on the silicon substrate of the contact hole, A semiconductor comprising a step of forming a thin silicon oxide film on the surface of a silicon substrate for preventing epitaxial growth of silicon, and a step of forming an aluminum alloy wiring containing silicon on the thin silicon oxide film. Device manufacturing method.