JPH05243228A - Interconnection structure - Google Patents

Abstract

PURPOSE:To obtain an interconnection structure which does not impede hydrogenation and passivation during a sintering process, has a superior barrier characteristic, and permits an ohmic contact to be made by forming an Al interconnection layer on a silicon substrate via silicide and titanium oxynitride layers. CONSTITUTION:An Al interconnection layer 4 is formed on a silicon substrate via a silicide layer 2 and a titanium oxynitride layer 3. For instance, in LSI manufacturing processes, a contact hole which is a connection hole 6 for connecting the Al-based interconnection layer 4 to the Si substrate 1 is formed on an interlayer film 5 made of SiO2 or the like. Thereafter, the titanium silicide layer 2 is formed over the entire interlayer film. The titanium oxynitride layer 3 and the Al-based interconnection layer 4 are formed in this order by sputtering. Alternately, it may be arranged in such a manner that the silicide layer 2 is formed by fitting half the connection hole 6 with TiSi, and the titanium oxynitride layer 3 is formed over the silicide layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wiring structure, and more particularly to a wiring structure in which an Al-based wiring layer is formed on a silicon substrate.

[0002]

2. Description of the Related Art Al wiring layers (pure Al
In addition, when forming a wiring layer made of a material having Al as a main material, such as an alloy of Si, Cu, etc. and Al, the Al wiring has a strong reactivity with Si, and therefore, Al wiring under It requires a barrier layer to prevent reaction. This barrier layer is required to have a function of blocking the reaction between Al and Si, as well as to have good coverage in the contact hole and good ohmic contact (connectivity). Conventionally, for example, as the barrier layer, Ti
And TiON are used.

An example of such a conventional technique is shown in FIG.
Conventionally, as shown in the figure, a Ti layer 2a and a T layer are formed on a Si substrate 1.
The iON layer 3 is laminated in this order, and the Al-based wiring layer 4 is formed thereon. In FIG. 4, 5 is an interlayer film such as SiO ₂ .
Reference numeral 6 is a connection hole (contact hole) formed on the substrate 1.

[0004]

However, in the conventional structure as described above, since Ti forming the Ti layer 2a does not permeate hydrogen, hydrogenation is hindered in the sintering process. Further, in the case of the structure without the Ti layer 2a, there arises a problem that good contact between Si and TiON cannot be obtained.

The present invention solves the above problems and provides a wiring structure in which an Al-based wiring layer is formed on a Si substrate. Hydrogenation in the sintering process is not hindered, and thus passivation is not hindered. Moreover, it is an object of the present invention to provide a wiring structure having a good barrier property and capable of forming an ohmic contact.

[0006]

The present invention is a wiring structure in which an Al-based wiring layer is formed on a silicon substrate via a silicide layer and a titanium oxynitride layer, and thereby achieves the above object. It is a thing.

In the present invention, titanium oxynitride is generally referred to as TiO, and the composition thereof does not necessarily have to be constant, but is generically expressed in the form of TiOx Ny.

[0008]

According to the present invention, since the silicide permeates hydrogen, the inhibition of passivation does not occur as a result of passing through the silicide layer. Further, since the silicide layer and the titanium oxynitride layer are sandwiched between the Al-based wiring layer and Si, the reaction between Al and Si does not occur. In addition, an ohmic contact can be taken for the connection of aluminum-based material / titanium oxynitride / silicide / Si.

FIG. 3 shows how the characteristics change depending on the type of the underlying layer of the Al-based wiring layer in each case. FIG. 3A shows a Ti / TiON / Al-Si structure,
The base of Al-Si (Al-Si alloy containing 1 wt% of Si) which is an Al-based wiring has TiON immediately below and Ti below that. FIG. 3B shows Ti / Al-.
In the Si structure, only Ti is below the Al-based wiring. Figure 3
(C) is a TiON / Al-Si structure, and there is only TiON under the Al-based wiring and no Ti.

As shown in FIGS. 3A and 3B, Ti is formed under Al--Si.
In contrast to the graphs I and II (Figs. 3 (a) and 3 (b)) in which Ti exists, graph III (Fig. 3 (c)) in which Ti is not present in the base
In regard to, the rising characteristics are good, that is, the relationship between the gate voltage and the drain current is good. Also, as indicated by the black circles, in graph III, the drain current is larger by about two digits for the same gate voltage than in graphs I and II, and the characteristics are good. this is,
It is considered that as a result of the absence of Ti, H infiltrated and the hydrogenation (sinter) was performed well.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. Of course, the present invention is not limited to the embodiments.

Example 1 This example is shown in FIG. As shown in the figure, the wiring structure of the present embodiment has an Al-based wiring layer 4 formed on a silicon substrate 1 with a silicide layer 2 (here, titanium silicide) and a titanium oxynitride (TiON) layer 3 interposed. Is.

The wiring structure of this embodiment was formed as follows. First, in the LSI manufacturing process, a contact hole which is a connection hole 6 for connecting the Al-based wiring layer 4 and the Si substrate 1 is formed in the interlayer film 5 (SiO ₂ or the like).

After that, a silicide layer 2, for example, titanium silicide in this case, is formed on the entire surface. Next, the titanium oxynitride (TiON) layer 3 and the Al-based wiring layer 4 are sequentially formed by sputtering.

That is, in this example, Ti 2 in the conventional example of FIG. 4 is used.
The silicide layer 2 is used instead of a.

Hitherto, although the penetration of hydrogen for passivation was impeded by Ti, hydrogenation has been sufficiently performed by replacing Ti with silicide (for example, TiSi).

On the other hand, in the conventional example of FIG. 4, when Si and TiON are directly connected without forming Ti, good ohmic contact cannot be obtained. However, with the structure of this embodiment, Si / TiSi / TiON / With the Al structure, ohmic contact was obtained and good connection could be achieved.

In this embodiment, as described above, the wiring structure of the semiconductor element has the wiring structure using silicide for the barrier layer of the Al-based wiring, so that the sinter functions well,
A device with good performance was obtained.

Second Embodiment FIG. 2 shows a second embodiment. This is a modification of the first embodiment. In this example, in the contact hole which is the connection hole 6,
The silicide layer 2 is selectively formed.

That is, as shown in FIG. 2, a silicide layer 2 is formed by burying TiSi up to the middle of the contact hole 6, and a titanium oxynitride (TiON) layer 3 is formed on the silicide layer 2. It exists only in the connection hole 6. With this structure, the same effect as that of the first embodiment can be obtained.

[0021]

As described above, according to the present invention, in the wiring structure in which the Al-based wiring layer is formed on the Si substrate, the hydrogenation in the sintering process is not hindered, and thus the passivation is not hindered. It was possible to provide a wiring structure having a good barrier property and capable of forming an ohmic contact.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing the structure of Example 1.

FIG. 2 is a cross-sectional view showing the structure of Example 2.

FIG. 3 is a diagram showing a characteristic change of an Al-based wiring layer due to a base structure.

FIG. 4 is a cross-sectional view showing a conventional technique.

[Explanation of symbols]

 1 Si substrate 2 Silicide layer 3 Titanium oxynitride layer 4 Al wiring layer

Claims (1)

[Claims] 1. A wiring structure in which an Al-based wiring layer is formed on a silicon substrate via a silicide layer and a titanium oxynitride layer.