JPH01222477A - Wiring connecting electrode and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain a contact electrode having a low contact resistance without possibility of forming of an insulation film by a method wherein a natural oxide film of a contact window is removed and a TiC layer is coated or formed thereon, and then an Al wiring layer is deposited. CONSTITUTION:A contact forming region is provided inside an Si substrate 1 and a contact forming window 3 is made on the surface of the substrate 1. The semiconductor substrate 1 is placed in a sputtering system, a natural oxide film formed on the surface of Si inside the window is first removed through a plasma etching of a short period and it follows that a TiC layer 5 is deposited thereon through an active etching. A process follows, where an Al layer 6 of a wiring layer is deposited through a sputtering. As mentioned above, an electrode of this design is structured so as to interpose TiC, so that only SiC and TiSi2 both small in resistivity are formed due to the reaction between TiC and Si even if the electrode is subjected to a heat treatment in the succeeding processes, consequently an excellent ohmic contact can be realized.

Description

[Detailed Description of the Invention] [Summary] The present invention relates to wiring connection electrodes, particularly contact electrodes, for semiconductor devices having Alfjl wires, and aims to form good ohmic contact between a Si substrate and Al wiring. This is a structure in which TiC is used as a barrier film between Aj/Si, and the manufacturing method is to remove the natural oxide film in the contact window, deposit or form a TiC layer, and then deposit an Al wiring layer. Configure it as follows.

[Industrial application field]

The present invention relates to a wiring connection electrode of a semiconductor device having Al wiring, and particularly to a barrier layer formed between A7/Si. Since the present invention exhibits excellent effects when applied to contact electrodes among wiring connection electrodes, the case of contact electrodes will be described below.

Most of the semiconductor devices handled in today's semiconductor industry are integrated circuits formed on Si3 plates.

Al is often used for the internal wiring of this Si-based integrated circuit 11i (IC), but when an Al layer is formed in contact with Si, Si atoms migrate into one layer. The contact becomes defective, and furthermore, the Si
A if the contact formation region on the substrate side is a shallow diffusion region
It occurs that l diffuses into the Si substrate and destroys the junctions within the Si substrate.

[Conventional technology]

In order to prevent such troubles, it is known to interpose a barrier film between Si and Al.

In recent years, titanium nitride (TiN) F@ of about 1,000 to 3,000 has been increasingly used as a material for this barrier film. Since TiN is chemically stable and has a relatively low resistivity, it is highly evaluated as a barrier material.

[Problem to be solved by the invention]

However, when a Si substrate provided with TiN as a barrier layer is subjected to heat treatment, the contact resistance may increase abnormally. This is considered to be because a film of silicon nitride (S i N x ), which is an insulator, was formed on the contact portion.

An object of the present invention is to provide a contact electrode with low contact resistance and a method for forming the same in a Si-based integrated circuit using Al wiring without the risk of forming an insulating film.

[Means to solve the problem]

In order to achieve the above object, the contact electrode of the present invention uses TiC as a barrier material, and in the manufacturing method, the natural oxide film in the contact window is removed,
After depositing or producing the TiC layer, A! A wiring layer is deposited and formed.

Furthermore, as a process for depositing the TiC layer, the TiC layer may be deposited within the contact window by reactive sputtering, or Ti may be deposited within the contact window by sputtering and then heat treated in a hydrocarbon gas atmosphere. It will be done.

[For production]

During the above process, when Ti is deposited on Si, the substances produced by heat treatment in a hydrocarbon gas atmosphere are TiC and Ti51g, and the contact electrode of the present invention is A7/S
A TiC film is provided between t and functions as a barrier.

When Tic reacts with Si, the substances produced are SiC and Ti51g, and SiC is a semiconductor, but if the target is the g iSI region containing impurities as in the present invention, Si
Since C is also doped with impurities, it exhibits conductivity, and Ti
5iz also has low resistance like normal silicide. Therefore T
There is no need to consider the reaction between iC and the Si substrate.

〔Example〕

FIG. 1 is a schematic cross-sectional view showing the structure of a contact electrode of the present invention corresponding to claim (1). As is clear from a comparison with FIG. 4, in the present invention, a T10 layer 5 is provided between the Si-based substrate color Al wiring 6. The TiC layer functions as a barrier film and prevents interaction between Al and Si.

FIG. 2 shows the steps of an embodiment corresponding to claim (2). Hereinafter, the steps of the first embodiment will be explained with reference to FIG.

Although the Si substrate region where the contact is formed is not particularly limited, the shape of this embodiment is assumed to be the base contact region of a bipolar transistor. Si
A contact formation region 2 is present in the substrate 1, and a contact formation window 3 is opened in the surface thereof. This state is shown in FIG. 2 (al), and 4 in the figure is an oxide film formed by selective oxidation.

The semiconductor substrate that has been processed up to this point is loaded into a sputtering device, and the natural oxide film present on the Si surface within the window is first removed by short-time plasma etching.

Subsequently, TiCJi5 is deposited by reactive sputtering. This is reaction gas Ar+CHn, DC power IKW
This is magnetron sputtering under certain conditions. The thickness of the deposited TiC layer may be 1000 Å or less.

Subsequently, an Al layer 6, which is a wiring layer, is deposited by sputtering.

The above processing realizes the state shown in FIG. 2(b). This is very similar to the structure shown in FIG. The method for forming the Al layer does not have to be sputtering, and may be a conventional vapor deposition method.

With a structure in which TiC is interposed in this way, even if heat treatment is performed in a subsequent process, the reaction between TiC and Si will only produce low resistivity SiC and Ti5iz, without producing an insulating material such as TiN. , a good ohmic contact is formed.

FIG. 3 shows the steps of an embodiment corresponding to claim (3). Hereinafter, the steps of the second embodiment will be explained with reference to FIG.

This embodiment is also the same as the first embodiment up to the point where the window is opened in the contact forming portion. The semiconductor substrate 1 with the contact window 3 opened therein is loaded into a sputtering device, and the natural oxide film present on the Si surface within the window is first removed by short-time plasma etching, and then the Ti layer 7 is deposited to a thickness of 1,000 yen by normal sputtering. Accumulates about the same amount as a person. This situation is shown in Figure 3 (al
is shown.

Subsequently, heat treatment is performed at 1000° C. for 10 minutes in a methane atmosphere. As a result, Ti reacted with Si becomes TiSix, and Ti reacted with C generated from methane becomes TiC. In addition to methane, a hydrocarbon such as propane can be used as the heat treatment atmosphere.

Subsequently, the Al wiring layer 6 is deposited in the same manner as in the first embodiment. This state is shown in FIG. 3(b), where 2 is a contact formation region, 4 is a selective oxide film, and 5 is TiCl3, which is Ti5iz. In this embodiment as well, since the low resistivity Ti5iz and Ti0 layers function as a barrier, a stable contact electrode with low contact resistance is formed.

Although the present invention has been described above in the case of a contact electrode provided on a Si substrate, those skilled in the art will easily understand that the present invention can also be applied to the case where a KL wiring is connected to a poly-Si wiring and exhibits considerable effects. .

〔Effect of the invention〕

As explained above, by the method of the present invention, a good contact of Al wiring can be formed on a Si substrate.

Furthermore, the present invention exhibits considerable effects when applied to the connection between poly-Si distribution and Aj wiring.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional schematic diagram showing the structure of the contact electrode of the present invention. FIG. 2 is a cross-sectional schematic diagram showing the manufacturing process of the first embodiment. FIG. 3 is a cross-sectional diagram showing the manufacturing process of the second embodiment. Schematic diagram FIG. 4 is a schematic cross-sectional diagram showing a known structure provided with a barrier film, in which 1 is a Si substrate, 2 is a contact formation region, 3 is a contact window, 4 is a selective oxide film, 5 is a TiC layer, 6 is an Al layer, 7 is a Ti layer, 8 is a Ti5iz layer, and 9 is a TiN layer. Fig. 1 is a cross-sectional schematic diagram showing the structure of the contact electrode of the present invention. Fig. 1 is a cross-sectional schematic diagram showing the manufacturing process of the first embodiment. Fig. 2 is a cross-sectional schematic diagram showing the manufacturing process of the second embodiment. Fig. 4 is a cross-sectional schematic diagram showing a known structure provided.

Claims (3)

[Claims] (1) A wiring connection electrode characterized in that a TiC film is provided between a monocrystalline or polycrystalline Si layer containing impurities and an Al wiring layer. (2) After opening a wiring connection electrode window on the surface of the single crystal or polycrystalline Si layer containing impurities, the natural oxide film within the wiring connection electrode window is removed, and at least the inside of the window is removed by reactive sputtering. 1. A method for manufacturing a wiring connection electrode, comprising the steps of: depositing a TiC layer on the substrate, and then depositing an Al layer. (3) After opening a wiring connection electrode window on the surface of the single crystal or polycrystalline Si layer containing impurities, removing the natural oxide film within the wiring connection electrode window, and sputtering at least Ti within the window. 1. A method for manufacturing a wiring connection electrode, comprising the steps of: depositing an Al layer, heat-treating it in a hydrocarbon gas atmosphere, and then depositing an Al layer.