KR20060112476A - Method for forming metal line of semiconductor device - Google Patents

Abstract

A method for forming a metal interconnection of a semiconductor device is provided to improve electrical properties and reliability of the metal interconnection by preventing segregation of a copper. A first metal film(20) is formed on a semiconductor substrate(10). Aluminum films(30,32,34,36) and copper films(40,42,44) are alternately and sequentially stacked on the first metal film. A second metal film(50) is formed on the resultant structure. Aluminum-copper alloy layers are formed by annealing the aluminum films and the copper films. By patterning the aluminum-copper alloy layers, a metal interconnection is then formed.

Description

METHOD FOR FORMING METAL LINE OF SEMICONDUCTOR DEVICE

1A through 1E are cross-sectional views illustrating a method of forming metal wirings in a semiconductor device according to an embodiment of the present invention.

<Explanation of symbols for main parts of drawing>

10 semiconductor substrate 20 first metal film

30, 32, 34, 36: aluminum film 40, 42, 44: copper film

50: second metal film 60: aluminum-copper alloy film

70: metal wiring

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device, and more particularly, to a method for forming a metal wiring of a semiconductor device, which can prevent the separation of copper when forming a metal wiring using an aluminum-copper alloy to improve electrical characteristics and reliability of the metal wiring. It is about.

In general, the metal material most used in the manufacturing process of the semiconductor device is aluminum (Al). The reason for this is that the electrical conductivity is good, the adhesion to the oxide film is excellent, and the molding is easy.

However, in the aluminum, voids and hillocks are formed on the straps due to electro migration (EM) or stress migration (SM). Here, electromigration is a defect which arises because the current density in metal wiring increases. As the wiring width becomes smaller, the current density in the wiring becomes higher due to the high speed operation of the device. The stress migration is a creep failure mode generated by applying mechanical stress to the wiring. This stress causes a difference in thermal expansion coefficient between the insulating film and the metal wiring in order to protect the wiring, and tends to be large as the wiring width becomes smaller. In other words, when a current flows through the wiring metal aluminum, aluminum atoms diffuse in a high current density region such as a contact region or a step region with silicon, and the metal wire in the portion becomes thin and eventually short-circuited. This electrical mass movement is caused by the slow diffusion of small amounts of electrical mass, which is triggered after considerable time after operation.

In order to solve the above problems, it can be solved by using an aluminum-copper alloy in which a small amount of copper (Cu) is added to aluminum.

However, in the method of forming a metal wiring using an aluminum-copper alloy, galvanic corrosion occurs during the solvent treatment after etching and ashing the metal wiring. This occurs when copper is separated when forming a film during deposition or when the separation is enhanced during etching. In particular, this copper separation occurs in the grain boundaries of aluminum and aluminum. That is, the separation of copper occurs a lot when copper is deposited at the point where the boundaries of the grains of aluminum meet.

Therefore, the method of forming a metal wiring of a semiconductor device using a general aluminum-copper alloy has a problem in that the distribution of aluminum and copper is uneven due to the above-described separation of copper, thereby deteriorating electrical characteristics and reliability of the metal wiring.

Accordingly, an object of the present invention is to solve the problems of the prior art, to prevent the separation of copper when forming a metal wiring using aluminum-copper alloy to improve the electrical properties and reliability of the metal wiring. The present invention provides a method for forming a metal wiring of a semiconductor device.

In order to achieve the above object, the method for forming a metal wiring of a semiconductor device according to an embodiment of the present invention comprises the steps of forming at least one layer of the first metal film on the semiconductor, and the aluminum film on the first metal film; Alternately forming a copper film in multiple layers, forming a second metal film on the semiconductor substrate on which the multilayer aluminum film and the copper film are formed, and forming the multilayer and aluminum film formed on the semiconductor substrate. Heat-treating to form an aluminum-copper alloy film, and patterning the aluminum-copper alloy film to form metal wiring.

The multilayer aluminum film and the copper film are formed by an atomic layer deposition process.

In the alternating multilayer formation of the multilayer aluminum film and the copper film, the uppermost layer is formed of an aluminum film, and in the alternating multilayer formation of the multilayer aluminum film and the copper film, an aluminum film is formed on the first metal film. .

The heat treatment temperature is characterized in that the 350 ℃ ~ 450 ℃ range.

Each copper film is formed to a thickness less than 1% of each aluminum film.

Hereinafter, with reference to the accompanying drawings, the configuration and operation according to a preferred embodiment of the present invention.

1A through 1E are cross-sectional views illustrating a method of forming metal wirings in a semiconductor device according to an embodiment of the present invention.

Referring to FIGS. 1A to 1E, a method of forming metal wirings of a semiconductor device according to an exemplary embodiment of the present invention will be described below.

First, as shown in FIG. 1A, a multilayered first metal film 20 is formed on a semiconductor substrate 10 using a sputtering process. In this case, the multilayer first metal film 20 is continuously formed of a material of titanium (Ti) and titanium nitride (TiN). The multilayered first metal film 20 serves as an adhesive.

Subsequently, as illustrated in FIG. 1B, first through M + 1 (though, on the semiconductor substrate 10 on which the multilayered first metal film 20 is formed using an atomic layer deposition (ALD) process), M alternately deposits the aluminum films 30, 32, 34, 36 of the positive integer) layer and the copper films 40, 42, 44 of the first to M layers. That is, on the first metal film 20 of the semiconductor substrate 10, the first aluminum film 30, the first copper film 40, the second aluminum film 32, the second copper film 42, and the third The aluminum film 34, the first copper film 44, the fourth aluminum film 36, ... are deposited to be repeated in order, and the aluminum film is deposited on the uppermost layer.

Here, each aluminum film 30, 32, 34, 36 and each copper film 40, 42, 44 may be adjusted according to a desired composition. Preferably, each aluminum film 30, 32, 34, 36 is deposited to a thickness of 1000 microseconds, while each copper film 40, 42, 44 is 10 microseconds of the aluminum films 30, 32, 34, 36. It is deposited to the following thickness. That is, each copper film 40, 42, 44 is deposited to a thickness of 1% or less of the aluminum film. For example, when the thickness of the aluminum film is 5000 kPa, M becomes '4' so that the aluminum film is deposited five times and the copper film is deposited four times.

Then, as illustrated in FIG. 1C, a second metal film 50 is deposited on the M + 1 aluminum film 36 formed on the uppermost layer of the semiconductor substrate 10 using a sputtering process. The second metal film 50 is formed by the same material and the same method as the first metal film 20.

Subsequently, as illustrated in FIG. 1D, the semiconductor substrate 10 having the second metal film 50 formed thereon may be thermally treated at a temperature in the range of 350 ° C. to 450 ° C. using a rapid thermal processing (RTP). do. Accordingly, the aluminum films 30, 32, 34, 36 and the copper films 40, 42, 44 alternately formed between the first and second metal films 20, 50 on the semiconductor substrate 10 are applied. Loss of heat turns into solid solution 60. That is, the aluminum films 30, 32, 34, 36 and the copper films 40, 42, 44 are dissolved by the applied heat, diffused, mixed evenly, and then hardened, thereby curing an aluminum-copper alloy film having a very homogeneous distribution ( 60).

Finally, the desired metal is patterned by patterning the aluminum-copper alloy film 60 between the first and second metal films 20, 50 formed on the semiconductor substrate 10 using a patterning process as shown in FIG. 1E. The wiring 70 is formed.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the embodiments, but should be defined by the claims.

As described above, in the method of forming a metal wiring of a semiconductor device according to an exemplary embodiment of the present invention, an aluminum film and a copper film are alternately continuously deposited on an semiconductor substrate, followed by annealing and patterning to use an aluminum-copper alloy. By forming the metal wiring to prevent the separation of copper. Therefore, the present invention can prevent the separation of copper when forming the metal wiring using the aluminum-copper alloy to improve the electrical properties and reliability of the metal wiring.

Claims (7)

Forming a first metal film on the semiconductor, Alternately forming an aluminum film and a copper film on the first metal film in multiple layers; Forming a second metal film on the semiconductor substrate on which the multilayer aluminum film and the copper film are formed; Thermally treating the aluminum film and the copper film formed in the multilayer formed on the semiconductor substrate to form an aluminum-copper alloy film; And forming a metal wiring by patterning the aluminum-copper alloy film. The method of claim 1, The multilayer aluminum film and the copper film are formed by an atomic layer deposition process. The method of claim 1, And wherein the uppermost layer is formed of an aluminum film in the alternating multilayer formation of the multilayer aluminum film and the copper film. The method of claim 1, And forming an aluminum film over the first metal film in the alternating multilayer formation of the multilayer aluminum film and the copper film. The method of claim 1, The heat treatment temperature is a metal wiring forming method of a semiconductor device, characterized in that the range of 350 ℃ ~ 450 ℃. The method of claim 1, Wherein each copper film is formed to a thickness less than 1% of each aluminum film. The method of claim 1, The first and the second metal film is a method of forming a metal wiring of the semiconductor device, characterized in that the titanium (Ti) and titanium nitide (TiN) is formed in multiple layers.

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