JPH0220142B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for manufacturing a semiconductor device using an aluminum (Al) film or an alloy film containing Al as a main component as an electrode wiring layer.

[Technical background of the invention and its problems]

Al has been widely used as an electrode wiring layer of semiconductor devices. Figure 1 shows 2 using Al wiring.
FIG. 3 is an element cross-sectional view showing a layer wiring structure. After forming the insulating film 12 on the silicon substrate 11, the first layer is
An Al wiring layer 13 is formed. Next, an interlayer insulating film 14 is deposited, and a second Al wiring layer 15 is formed thereon to obtain a two-layer wiring structure.

In order to obtain such a structure, the interlayer insulating film 14 is usually formed at about 400° C. by the CVD method. At this time, hills 16 are likely to be formed on the first Al wiring layer 13. These hillocks 16 cause abnormal growth of the interlayer insulating film 14, which weakens the mechanical strength of the insulating film 14 and causes cracks 17. The crack 17 may cause a short circuit between the second Al wiring layer 15 on the interlayer insulating film 13 and the first Al wiring layer 13, or corrosion of the Al wiring due to penetration of chemicals through the crack. This causes a significant decrease in the reliability of Al wiring.

As described above, Al hillocks are an important problem that must be solved in multilayer wiring. Various solutions to this problem have been studied over the past ten years, but no perfect method has yet been found.

On the other hand, in semiconductor integrated circuits, the Al wiring width is becoming smaller and smaller from 2μ to 1μ as elements become smaller and more highly integrated. Because the current density is high in fine Al interconnects, disconnection of Al interconnects due to electromigration is a major cause of reduced reliability. Many methods have been proposed to prevent electromigration of Al wiring. For example, if a few percent of Cu is included in Al,
A method has been proposed in which Al--Cu intermetallic compounds are precipitated at the grain boundaries of Al interconnects by heat treatment, thereby preventing migration of Al atoms. However, this method is still not sufficient as a countermeasure against electromigration.

Furthermore, as a method for forming interconnects that are resistant to electromigration, Al
There is a method of providing a metal layer 25 of Ti, Cr, V, Mo, etc. in the middle of the wiring layer 24. After providing a diffusion region 22 in a silicon substrate 21, forming an insulating film 23, making a contact hole and depositing an Al wiring layer ₂₄₁ , a metal layer 25 such as Ti is provided, and then an Al wiring layer 241 is deposited. 24 ₂ was formed.

After forming the wiring layer into a laminated structure as described above, heat treatment causes the Ti and Al in the middle to react.
An alloy layer with Al is formed. This alloy metal has the effect of making the flow of Al atoms uniform due to electromigration and the effect of suppressing the growth of Al hills, and as a result, strengthens the electromigration resistance of the Al wiring.

However, in this method, heat treatment
Not only Al and Ti react, but also Si
It also causes a reaction. That is, a ternary alloy of Al-Si-Ti is formed. Since this Si is supplied from the diffusion layer 22 under the contact hole, which is the contact portion between the Al wiring 24 and the silicon substrate 21, spikes 26 as shown in the figure are formed, which causes junction breakdown.

[Purpose of the invention]

The present invention has been made in view of the above points, and is a semiconductor that suppresses the occurrence of hillocks, improves electromigration resistance characteristics, and realizes highly reliable Al interconnects that do not cause junction breakdown in contact hole areas. A method for manufacturing the device is provided.

[Summary of the invention]

The present invention forms a metal film containing a mixture of three elements, Al, Si, and another type of metal, on at least one of the inside or surface of an Al wiring layer, and heat-treats the metal film to form an alloy consisting of the three elements. It is characterized by forming a film or an intermetallic compound film.

Here, other metals added together with Al and Si may be metals such as Ti, Cr, V, and Mo, as long as they form a ternary alloy with Al and Si. Also, the present invention
The Al wiring layer may be not only a pure Al film, but also an alloy film containing Si, Cu, etc., whose main component is Al.

〔Effect of the invention〕

According to the present invention, the alloy film formed inside or on the surface of the Al wiring layer has the effect of suppressing the occurrence of hillocks in the Al wiring and greatly improving the electromigration resistance. In addition, since these alloy films or intermetallic compound films contain Si in advance, the supply of Si from the substrate is eliminated during the heat treatment process, thereby preventing bond breakdown at the contact hole portion. As described above, according to the present invention, highly reliable Al wiring can be formed.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings. 3A to 3D are process sectional views for explaining the manufacturing process of an embodiment of the present invention. First, Figure 3a
As shown in the figure, a diffusion layer 32 is formed on a P-type silicon substrate 31.
After forming, it is covered with an insulating film 33, a contact hole is opened, and an Al film or a Cu film mainly composed of Al is formed.
Alternatively, an Al alloy film 34 with Si is formed with a thickness of 0.5 to 1.0 μm. Next, a metal film 35 made of the three elements Al--Ti--Si is formed on the Al film 34 to a thickness of 100 to 1000 Å (FIG. 3b). The method for forming the metal film 35 made of the three elements Al-Ti-Si is, for example, Ax,
There are methods of depositing Ti and Si simultaneously from different sources, and methods of forming by sputtering from a target containing predetermined amounts of Ti, Al, and Si. In addition, the composition ratio of Al-Ti-Si is 1 to 1% of the total.
5wt%, and the remaining 99-50% is the composition ratio of Ti and Si.
The amount should be such that TiSi ₂ is obtained. After forming a laminated film of the Al film 34 and the metal film 35 made of the three elements Al-Ti-Si in this way, heat treatment at 300 to 500°C causes the two layers to become alloyed, as shown in Figure 3c. As a result,
Al-Ti-Si alloy film (or Ti ₇ Si ₁₂ Al ₅
An intermetallic compound film) 35' is formed. Since this alloy film 35' mechanically covers the Al film 34 from above and has the effect of suppressing hillocks, hillocks can be almost completely eliminated. After patterning the first wiring layer, an interlayer insulating film 36 is formed on the first wiring layer, as shown in FIG. 3d.
A second wiring layer is formed by depositing an Al film 37.

The two-layer wiring structure obtained in this way has no hills on the first wiring layer, so
Short circuits between wiring layers are completely eliminated. Furthermore, since the insulating film is no longer destroyed by hills, corrosion of the wiring and the like no longer occur. Furthermore, since hillock growth is suppressed, defects caused by electromigration are less likely to occur, and the life of the wiring is extended, allowing more current to flow. Also, in the process of forming the alloy film 35', the substrate 3
Since there is no supply of Si from 1, there is no possibility of junction breakdown of the diffusion layer 32 at the contact hole portion.

Next, another embodiment of the present invention will be described. FIGS. 4a and 4b are process sectional views of the embodiment. After providing the diffusion layer 42 in the silicon substrate 41, the diffusion layer 4
An insulating film 43 is formed on portions other than 2. Thereafter, an Al film 44 ₁ is deposited to a thickness of, for example, 0.4 μm.
Next, a metal film 45 consisting of the three elements Al-Ti-Si is formed.
is formed with a thickness of 500 to 1000 Å. This Al−Ti−
The method and conditions for forming the metal film 45 made of the three elements Si are the same as in the previous embodiment. After this, Al again
A film 44 ₂ is formed (FIG. 4a).

Al44 ₁ /Al-Ti-Si45/Al44 as above
After _{the two} laminated films are formed, heat treatment is performed at 300 to 500°C to obtain an Al wiring layer in which alloying occurs and an Al-Ti-Si alloy film 45' is formed inside (FIG. 4b).

In this embodiment as well, the alloy film 45' has the effect of making the flow of Al atoms uniform due to electromigration and suppressing the growth of Al hillocks, and as a result, strengthens the electromigration resistance characteristics of the Al wiring. do. Furthermore, since Si is included in advance, it has the effect of preventing destruction of the diffusion bond.

Another embodiment will be explained with reference to FIGS. 5 and 6. In the example shown in FIG. 5, after an insulating film 53 is formed on a silicon substrate 51 on which a diffusion layer 52 is formed, the same process as in the above embodiment is repeated to form Al-Ti-Si alloy films 55 ₁ and 55 ₂ inside. and Al film 54 formed on the surface.
The wiring layer is formed using the following methods. This makes it possible to more effectively prevent the occurrence of hillocks in the Al film 54 and improve electromigration resistance. In the example of FIG. 6, after forming an insulating film 63 on a silicon substrate 61 on which a diffusion layer 62 is formed,
An Al film 64 is formed in which two layers of Al-Ti-Si alloy films 65 ₁ and 65 ₂ are formed. In this way, by forming a multilayer Al-Ti-Si alloy film in the Al wiring, the electromigration resistance is further improved.

[Brief explanation of drawings]

1 and 2 are cross-sectional views of an element according to a conventional manufacturing method, FIGS. 3 a to d are cross-sectional views of an element showing steps of an embodiment of the present invention, and FIGS. FIGS. 5 and 6 are cross-sectional views of elements according to still other embodiments. 31, 41, 51, 61...Silicon substrate, 3
2, 42, 52, 62...diffusion layer, 33, 43,
53, 63... Insulating film, 34, 44, 54, 64
...Al film, 35,45...Metal film consisting of Al, Ti, Si, 35', 45', 55 ₁ , 55 ₂ , 65 ₁ ,
65 ₂ ...Al-Ti-Si alloy film.

Claims (1)

[Claims] 1 Al film or Al film is applied to the semiconductor substrate via an insulating film.
A method for manufacturing a semiconductor device including a step of forming a wiring layer made of an alloy film mainly composed of Al,
A method for manufacturing a semiconductor device, comprising the steps of forming a metal film containing a mixture of three elements, Si and other metals, and performing heat treatment to form an alloy film or an intermetallic compound film made of the three elements. .