JPS63142834A - Semiconductor device - Google Patents

Abstract

PURPOSE:To suppress the generation of voids and an electromigration by providing a coating film made of high melting point metal or its silicide on an aluminum film or an aluminum alloy film in a metal wiring structure to eliminate a hillock and to prevent the insulating characteristic and moisture resistance of an insulating film from being deteriorated. CONSTITUTION:An element separating field oxide film 12 is formed on a semiconductor substrate 11, and a gate oxide film 13, a gate electrode 14 and an interlayer insulating film 15 are then sequentially formed. An aluminum alloy (e.g., Al. 1%Si) film 16 is first formed by DC magnetron sputtering method on the film 15. Thereafter, a TiW film 17 of approx. 250Angstrom thick is formed under the conditions that the formed film has a compression stress by a DC magnetron sputtering method on the film 16 in the same vacuum. In the case of the TiW, the internal stress in the film is determined by Ar pressure and power. Metal wirings (aluminum alloy film + TiW film) 18 is formed in lithography step. Then, an insulating film 19 is formed, and heat treated.

Description

[Detailed description of the invention] <Industrial application field> The present invention relates to semiconductor devices, and particularly to semiconductor devices.

This relates to the structure of the metal wiring.

<Prior Art> As semiconductor integrated circuit devices become more sophisticated and denser, metal wiring is laid out in multiple layers.

Figure 2 shows the structure of a conventional semiconductor integrated circuit device and its manufacturing process. show.

Figure 1@2: A field oxide film 2 for element isolation is formed on a semiconductor substrate 1, and then a gate oxide film 3. Gate electrode 4 and interlayer insulating film 5 are formed.

- Figure 2 (bl) A metal film (Ai or A1 alloy film) 6' for forming metal wiring is formed.

・FIG. 2 fcl After resist coating, a mask 7 is formed through exposure and development.

2 [dl] Thereafter, reactive ion etching 2 is performed to form metal wiring 6. After cleaning, an insulating film 8 is formed, heat treatment is performed, and then a second layer of metal wiring 9 is formed. Note that in the case of single-layer wiring, a final heat treatment is performed after forming the insulating film.

<Problems to be Solved by the Invention> 75) However, the above-mentioned conventional semiconductor device has the following problems.

Insulating film is formed on metal wiring, and the metal film surface is heated through heat treatment.

Furthermore, electromigration also becomes a big problem with miniaturization.

The present invention aims to solve the above problems.

<Means for Solving the Problems> The structure of the metal wiring is such that a coating film made of a high melting point metal or its silicide is formed on an Ar film or an Ar alloy film. Furthermore, the coating film is a film having compressive pressure.

Effect> The formation of hillocks can be suppressed by providing a hard coating film made of a high melting point metal or its silicide. By making the above-mentioned coating film a film having compressive stress, a force that presses down the Ar film and the A-alloy film will act, which will be more effective in preventing the occurrence of hillocks. Further, by providing the same coating film, the movement of 9A can be suppressed, so it is effective against void generation and electromigration.

<Example> Hereinafter, the invention will be described in detail based on examples.

FIG. 1 is a diagram showing the structure and manufacturing process of an embodiment of the present invention.

・FIG. 1(a) A field oxide film In for element isolation is formed on the semiconductor substrate 11, and then a gate oxide film 13°, a gate electrode 14, and an interlayer insulating film 15 are formed.

First, an A1 alloy (for example, Al/1% Si) film 16 is formed on the interlayer insulating film 15 by DC magnetron sputtering. after that.

In the same vacuum, a TiW film 17 with a thickness of about 250λ is formed on the A1 alloy film 16 by DC magnetron sputtering under conditions that the formed film has compressive stress.

In the case of TiW, the internal stress in the film is determined by the Ar pressure and power (see Figure 3 [al, fb)]. Here, by selecting the conditions of Ar pressure 8 mtorr and power IKw, 5 X l O"dyn,/s"
It is possible to form a TiW film having a compressive stress of .

・Figure 1 ibl Metal wiring (Al alloy film + Ti
W@) Form 1g. After that, an insulating film 19 is formed,
Perform heat treatment.

Normally, as shown in FIG. 4, hillocks are formed in a single layer of Ar.Si, but no hillocks are formed in a structure of TiW/A-Si.

*If the TiW film is thick, Ar・5 i (7) Lateral hillocks will occur in the lateral direction.
) occurs, but this can also be suppressed by selecting a film thickness of 250 to 5 ooi.

In the conventional technology, when a material with a high reflectance such as Ar/Si is used for forming metal wiring.

During the subsequent photolithography process, the resist becomes overexposed due to the reflection of light on the metal film surface, and the resist becomes smaller than the mask width, or the light is concentrated locally, causing the pattern to become blurred. phenomenon is a big problem. The situation is shown in FIG. 5 (top view, an Al/Si film is formed on the entire surface). The arrow indicates the path of the diffusely reflected light.

71 is the constriction of the mask 7.

If a TiW film is formed on an Ar/Si film as previously proposed, the reflectance of the TiW film on Ar/Si will be halved to approximately 50%, as shown in Fig. 6, and the halation prevention as described above will be reduced. is also very effective.

In the above embodiment, the TiW film 1 is placed on the A1 alloy film 16.
After forming 7, microfabrication (etching) is performed to form metal wiring 18.
Formation of Al/1%Si film) → After microfabrication, go through the normal cleaning process.

A coating film made of a high melting point metal or its silicide may be formed by CVD or the like. For example, W.F.
When using a+H2 gas, the temperature is around 400℃, 0.1
A W film can be selectively formed on an Ai alloy film at a pressure of ~1 torr. In this case, as shown in FIG.

Since the W film 23 is formed not only on the upper surface of the A1 alloy film 22 but also on the side walls, hillocks can be suppressed in all directions.

In addition, in the figure, 21 is an interlayer insulating film.

<Effect of the invention> As explained in detail above, according to the invention.

No hillocks occur in metal wiring, and the insulation properties of the insulation film.

Deterioration of moisture resistance can be prevented. Moreover, since the generation of voids and electromigration accompanying the recrystallization of A can be suppressed, it is also possible to prevent disconnection of metal wiring, etc.

As described above, the present invention provides a technology that is extremely effective for increasing the density of semiconductor devices, multilayer wiring, and the like.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the structure and manufacturing process of an embodiment of the invention, FIG. 2 is a diagram showing the structure of a conventional semiconductor integrated circuit device and its manufacturing process, and FIG. 3 is a diagram showing the structure of a conventional semiconductor integrated circuit device and its manufacturing process. Figure 4 shows the relationship between the formation conditions and the internal stress in the film when forming the film, and shows the relationship between the metal wiring in the case of an A-Si single layer and the TiW/A-Si structure. Figure 5 shows the hillock density for each, Figure @5 shows how the strip width narrows due to halation in the conventional technology, Figure 6 shows the reflectance of the TiW film, and Figure 7 FIG. 7 is a cross-sectional view for explaining another embodiment. Explanation of symbols 16: U alloy film, Summer 7: TiW film, 18: Synthetic fiber wiring,
22: A alloy film, 23: W film. Agent: Patent attorney Takeshi Sugiyama (and 1 other person) o
-0 Product C Hebe Ren'cho

Claims (2)

[Claims] (1) A semiconductor device characterized in that a metal wiring is provided with a structure in which a coating film made of a high melting point metal or its silicide is formed on an Al film or an Al alloy film. (2) The semiconductor device according to claim (1), wherein the coating film is a film having compressive stress.