Method for formation of copper diffusion barrier film using aluminum

1. Field of the Invention

The present invention relates to a method for formation of copper diffusion barrier film using aluminum, and more particularly to a method for formation of copper diffusion barrier film in a method for formation of copper wiring employing a chemical-mechanical polishing (CMP) process, in which a thin aluminum film is deposited on a dielectric, the aluminum film is transformed into a nitride film basically composed of aluminum nitride (hereinafter, AlxNy), an aluminum film is deposited again on the transformed nitride film, and copper is deposited on the deposited aluminum film.

2. Description of the Prior Art

As generally known in the art, in a method for formation of metal wiring employing a CMP process, copper, which is one of wiring materials used for wiring semiconductor devices, is utilized as a metalization material which can reduce resistance-capacitance (RC) delay as its electric conductivity is low.

FIG. 1 a and FIG. 1 b are views showing a process for formation of copper diffusion barrier film in accordance with the prior art, wherein copper is deposited through electroplating, and then, is subjected to a conventional CMP process, which is not shown.

Copper is deposited through a Damascene process developed by IBM Inc., and is subjected to a CMP process. That is, a dielectric S 1 pattern is formed on a substrate, then a copper diffusion barrier film S 2 composed of titanium (Ti), titanium nitride (TiN), tantalum (Ta), and tantalum nitride (TaN), etc., is formed on the dielectric pattern, copper S 3 is deposited on the copper diffusion barrier film through electroplating, and the copper is then subjected to the CMP process.

However, because of the high diffusion coefficient of copper in almost all (of the materials used in semiconductor fabrication, resulting in the deterioration of their transistor (TR) property, several kinds of diffusion barrier films have been developed and used in order to suppress the diffusion of copper.

Further, one more significant problem is that leakages between metal lines increase as pitches between the metals decrease, due to the high integration of semiconductor devices.

Accordingly, the present invention has been made to solve the above-mentioned problems occurring in the prior art, and an object of the present invention is to provide a method for formation of copper diffusion barrier film using aluminum, in which a first aluminum film is deposited on a dielectric, a surface of the first aluminum film is transformed to a nitride film basically composed of aluminum nitride (AlxNy) by plasma treating the surface of the first deposited aluminum film with NH 3 or N 2 , then a second aluminum film is deposited again on the transformed aluminum nitride film, and copper is deposited on the second deposited aluminum film.

In order to accomplish this object, there is provided a method for formation of copper diffusion barrier film using aluminum, the method comprising: a first step of depositing a first aluminum film on a dielectric; a second step of plasma treating the surface of the first deposited aluminum with NH 3 or N 2 , thereby transforming the plasma treated surface of the first aluminum film into a nitride film basically composed of aluminum nitride (AlxNy); a third step of depositing a second aluminum film on the transformed nitride film; and a fourth step of depositing a copper on the second aluminum film deposited.

The above and other objects, features and advantages of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIGS. 1 a and 1 b are views showing a process for formation of copper diffusion barrier film in accordance with the prior art, wherein copper is deposited through electroplating, and then, is subjected to a conventional CMP process, which is not shown; and

FIGS. 2 a to 2 d are views showing a process for formation of copper diffusion barrier film using aluminum in accordance with the present invention, wherein a conventional CMP process can be performed after the deposition of copper, which is not shown.

Hereinafter, a preferred embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 2 a to FIG. 2 d show a method for formation of copper diffusion barrier film using aluminum in accordance with the present invention. The method of the present invention comprises steps of: depositing a first aluminum film (Al) S 4 on a dielectric S 1 , plasma treating a surface of the deposited aluminum film S 4 with NH 3 , thereby transforming the plasma treated surface of the first aluminum film S 4 into a nitride film basically composed of aluminum nitride (AlxNy) S 5 , depositing a second aluminum film (Al) S 6 on the transformed nitride film, and depositing copper (Cu) S 7 on the second deposited aluminum film S 6 .

Based on the above-mentioned process, the method for formation of copper diffusion barrier film using aluminum according to the present invention will be described in more detail hereinafter.

As shown in FIG. 2 a , a thin aluminum (Al) film S 4 is firstly deposited on a dielectric S 1 . At this step, the aluminum film S 4 is deposited through a sputtering method or a chemical vapor deposition method (CVD) and has a thickness of at most 100Å.

Then, as shown in FIG. 2 b , a plasma treatment is performed with NH 3 or N 2 on a surface of the first deposited aluminum film S 4 , so that the plasma treated surface of the first aluminum film is transformed into a nitride film basically composed of aluminum nitride (AlxNy) S 5 .

Subsequently, as shown in FIG. 2 c , a second aluminum (Al) film S 6 is again deposited on the transformed nitride film S 5 . At this step, the second aluminum film S 6 is deposited through a sputtering method or a chemical vapor deposition method (CVD) and has a thickness of at most 100Å.

Finally, as shown in FIG. 2 d , copper (Cu) S 7 is deposited on the second deposited aluminum film S 6 in order to form a copper diffusion barrier film.

Therefore, as described above, the method according to the present invention comprises the steps of: depositing a first thin aluminum film on a dielectric, transforming the surface of the first deposited aluminum film into a nitride film basically composed of aluminum nitride (AlxNy) by plasma treatment with NH 3 or N 2 , depositing a second aluminum film on the transformed aluminum nitride film, and depositing a copper on the second deposited aluminum film. Therefore, the method according to the present invention can suppress the diffusion of copper and prevent leakages due to the copper diffusion between metal lines from increasing according to the decrease of pitches between the metals as semiconductor devices are more highly integrated.

Although a preferred embodiment of the present invention has been described for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as defined by the accompanying claims.