JPH06318595A - Method for manufacturing wiring structure of semiconductor integrated circuit - Google Patents

Abstract

(57) [Abstract] [Purpose] When a Cu wiring is used, the wiring of a semiconductor integrated circuit prevents diffusion of Cu of a wiring material into an insulating film or a substrate and suppresses an increase in electric resistance of the entire wiring. A method for manufacturing a structure is provided. [Structure] 4000 Å insulating film 12 on the surface of Si substrate 10
To form. The entire surface of this insulating film 12 has a film thickness of 200Å
W film 14 is formed. Furthermore, on the surface of the W film 14,
Ion energy 10 keV, dose 2 × 10 ¹⁷ at
Nitrogen ions of om / cm ² are implanted to form a tungsten nitride film 16 of about 100 Å on the surface of the W film 14.
A Cu film 18 is formed on the surface of the tungsten nitride film 16.
00Å formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a semiconductor integrated circuit (LS).
I) A method for manufacturing a wiring structure.

[0002]

2. Description of the Related Art At present, as a wiring material of a semiconductor integrated circuit, Al or Al obtained by adding Si or Cu to Al is used.
Alloys are used. Since Al is mainly used for such wiring, the allowable current density of the wiring is limited to (2 to 3) × 10 ⁵ A / cm ² or less.
The reason for this is that if a current exceeding the permissible current density is applied to this wiring, the wiring will be broken due to electromigration. In order to pass a current with a high current density, 0.1 to 5% Cu is contained in Al as a wiring material.
Although an Al-Cu alloy added with may be used,
Resistance to electromigration is unsatisfactory. Moreover, although the allowable current density is improved, the specific resistance of the wiring is increased, which causes a problem of reliability deterioration due to heat generation.

Further, as an underlayer of Al-Cu alloy wiring, T
Although a nitride film such as iN is also formed,
Since nitride has a high electric resistance, there is a problem that the substantial wiring resistance increases. On the other hand, in order to improve the electromigration resistance of the wiring, it has been proposed to use Cu wiring, which is substantially Cu and has high electromigration resistance, instead of the Al wiring or the Al alloy wiring.

[0004]

However, Cu is more likely to diffuse into Si (substrate) or SiO ₂ (insulating film) than Al, which causes a problem that the normal operation of the transistor is hindered. In order to solve this problem, a structure in which the wiring is covered with a metal nitride or boride has been proposed (see Japanese Patent Laid-Open No. 1-202841). However, while these nitrides or borides have the effect of preventing the diffusion of Cu, they have high electrical resistance. Therefore, when the wiring is covered with nitride or boride, the resistance of the entire wiring increases, and the merit of using Cu, which is a low resistance material, for the wiring is reduced.

In view of the above circumstances, the present invention prevents the diffusion of Cu into the insulating film and the substrate and suppresses the increase of the electric resistance of the entire wiring when the Cu wiring is used. An object is to provide a method for manufacturing a structure.

[0006]

A method of manufacturing a wiring structure of a semiconductor integrated circuit according to the present invention for achieving the above object comprises:
In a method of manufacturing a wiring structure for a semiconductor integrated circuit, a metal barrier film is formed on an insulating film, and one surface selected from B, N, and C is ion-implanted on the surface of the metal barrier film,
A wiring is formed on the ion-implanted metal barrier film.

The material of the metal barrier film is not particularly limited, but W, Ta and alloys thereof having a small self-diffusion coefficient among transition metals and an excellent Cu diffusion preventing effect are preferable. Ta film W film Ta-W alloy film Ta alloy film containing one or more metals selected from Nb, Mo, and Ti W alloy containing one or more metals selected from Nb, Mo, Pd, and Pb Film Ta-W alloy film added with Nb and / or Mo is preferable.

[0008]

In the method for manufacturing a wiring structure for a semiconductor integrated circuit according to the present invention, by controlling the energy of ion implantation,
Very thin nitride on the surface of the already deposited metal barrier film,
Borides or carbides can be formed. As a result, it becomes possible to reduce the resistance of the entire wiring as compared with the conventional case where the entire barrier film is made of nitride, boride or carbide. The crystal structure of these nitrides, borides, and carbides obtained by ion implantation is close to an amorphous structure. Therefore, even if the film thickness of these nitrides is thin, Cu grain boundary diffusion can be suppressed and the barrier property is improved. It will not be damaged. Further, as compared with the reactive sputtering of nitrogen and the sputtering method of metal borides, the ion implantation method makes it easier to control the amount of N, B, or C added, and the excessive N, B, or C content in the barrier film can be controlled. It is easy to prevent addition. Therefore, there is also an effect of reducing variations in wiring resistance.

[0009]

EXAMPLES Examples of the present invention will be described below. First, a method of manufacturing a wiring structure using a W film as a metal barrier film will be described with reference to FIG. As shown in FIG. 1A, 4000 Å BPSG (B
orophosphosilicate glass)
The insulating film 12 is formed. On the entire surface of this insulating film 12,
A W film 14 having a film thickness of 200Å is formed at a film forming rate of 10Å / s by RF magnetron sputtering in an Ar atmosphere of 1 mTorr. Further, the surface of the W film 14 has an ion energy of 10 keV and a dose of 2 × 10 ¹⁷ ato.
Nitrogen ions of m / cm ² are implanted to form a tungsten nitride film 16 of about 100 Å. RF is applied to the surface of the tungsten nitride film 16 in an Ar atmosphere at a total pressure of 2 mTorr.
Deposition rate of 60Å by magnetron sputtering
/ S, the Cu film 18 is grown to 5000 Å. afterwards,
As shown in FIG. 1B, the W film 14, the tungsten nitride film 16, and the Cu film 18 are patterned to form a Cu wiring 18a. After that, as shown in FIG. 1 (c), W is added to the base films 14a and 16a by the CVD method.
Then, a W coating film 20 is formed by selectively growing 400 Å only on the outer surface of the Cu wiring 18a. The W coating film 20 has a sample temperature of 200 to 400 ° C., a mixed gas of WF ₆ and H ₂ is supplied to the film forming chamber, and the pressure of the mixed gas is 1 Torr.
It is formed as follows. According to this film forming method, the interface reaction becomes rate-determining, and W can be selectively grown only on the outer surfaces of the base films 14a and 16a and the Cu wiring 18a. here,
In order to make this wiring structure multi-layered, an insulating film such as a SiO ₂ film may be formed on the W coating film 20, and the wiring structure described above may be formed on this insulating film by the same method. .

Next, examples of the wiring structure manufactured by the manufacturing method of the present invention will be described together with comparative examples. Table 1 shows the test results comparing the difference in the barrier properties against Cu of the barrier layers formed of various barrier materials and having a thickness of 1000Å. Here, for example, W-C / W represents a barrier film formed by ion-implanting C into the W film to form a W carbide film (W-C). Further, the comparative examples shown in 1) and 2) were formed by sputtering a compound material and reactive sputtering, respectively.

Each sample is a 500 formed on a Si substrate.
A barrier layer made of the barrier material shown in Table 1 is formed on the Cu film of 0Å, and the barrier layer is formed in a H ₂ gas atmosphere at 610
It was manufactured by applying a heat treatment of ℃ × 4h. Then, the Cu concentration diffused on the Si substrate surface and the resistance value were measured. Si
The Cu concentration on the substrate surface is SIMS (Secondary
-Ion Mass Spectroscopy).

[0012]

[Table 1] As is clear from Table 1, according to the present invention, Cu contamination can be suppressed as compared with the compound film produced by the conventional technique without increasing the effective resistance.

[0013]

As described above, according to the method of manufacturing a wiring structure for a semiconductor integrated circuit of the present invention, the metal compound film formed by ion implantation is used as the underlying film of the wiring.
It is possible to reduce the resistance of the entire wiring without impairing the diffusion of Cu. Therefore, according to the present invention, it is possible to realize a Cu wiring which has a smaller specific resistance than an Al alloy and is excellent in electromigration resistance and has a great industrial significance.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a method for manufacturing a wiring structure of the present invention.

[Explanation of symbols]

 10 Si substrate 12 Insulating film 14 W film 14a, 16a Underlayer film 16 Tungsten nitride film 18 Cu film 18a Cu wiring 20 W coating film

Claims (1)

[Claims] 1. A method for manufacturing a wiring structure of a semiconductor integrated circuit, comprising forming a metal barrier film on an insulating film, and forming one kind of B, N and C on the surface of the metal barrier film. A method of manufacturing a wiring structure of a semiconductor integrated circuit, which comprises ion-implanting and forming wiring on the ion-implanted metal barrier film.