KR100784099B1 - Method for forming wiring in semiconductor device - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a wiring of a semiconductor device for reducing electrical resistance and improving electrical characteristics, the method comprising: forming an amorphous silicide film or an amorphous TiSiN film on a semiconductor substrate on which a predetermined structure is formed; And forming a conductive film for wiring on the amorphous TiSiN film.

Amorphous silicide film, grain size, resistivity

Description

Method for forming wiring in semiconductor device

1 is a graph measuring the specific resistance (Rs) of PVD tungsten according to the type of under layer

2A to 2D are cross-sectional views of a wiring forming process of a semiconductor device according to a first exemplary embodiment of the present invention.

3A to 3C are cross-sectional views of a wiring forming process of a semiconductor device according to a second exemplary embodiment of the present invention.

Figure 4 is a graph comparing the specific resistance (Rs) of the wiring formed by the prior art and the present invention

<Explanation of symbols for main parts of the drawings>

11 adhesive layer 12 barrier metal film

13: amorphous silicide film or amorphous TiSiN film

14: ohmic contact layer 15: conductive film for wiring

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a wiring of a semiconductor element, and more particularly to a method for forming a wiring of a semiconductor element to reduce the resistance of the wiring.

As the line width of semiconductor devices becomes smaller and the degree of integration increases, the wiring formation method using the conventional reactive ion etching (RIE) process cannot satisfy the required wiring line width. Therefore, the wiring formation method using the damascene method is widely used now.

In the case of the damascene method, the wiring material must be deposited and buried in a pattern region formed in trench and contact form unlike the RIE (Reactive Ion Etching) method. do.

In general, semiconductor devices use tungsten (W) as the conductive film for the main wiring material. Tungsten uses WF ₆ as the deposition gas, and thus, TiN, TaN, TiW, etc., which have a higher resistance than tungsten before forming tungsten, are used. As a result, a barrier metal layer must be deposited. Currently, TiN is mainly used by chemical vapor deposition, which has excellent step coverage due to the miniaturization of wiring.

In addition, before forming the TiN film, a general method is to deposit a Ti film, which is an adhesive layer, for the purpose of forming TiSi _x for electrical ohmic contact and improving adhesion.

Such a Ti / TiN film should be deposited over a certain thickness before depositing tungsten (W), which is a conductive film for the main wiring material, and in the actual wiring structure, the Ti / TiN film occupies a considerable thickness. In particular, since the damascene method forms a Ti / TiN film and a tungsten film in the trenches which are already formed, unlike the RIE method, the Ti / TiN film has a three-dimensional structure and thus the Ti / TiN film has a larger specific gravity. In addition, as the wiring structure becomes finer, the specific gravity of the Ti / TiN film becomes larger, resulting in poor deposition and embedding of tungsten, a conductive film for the main wiring material, resulting in a decrease in volume of the conductive film for the main wiring material and a conductive film for the main wiring material. Problems such as void formation in the interior are caused. As a result, the wiring resistance is increased and the electrical characteristics are deteriorated.

In order to improve the embedding and electrical properties of the conductive film for the main wiring material, the easiest and most reliable method is to reduce the thickness of the barrier metal film to increase the specific gravity of the conductive film for the main wiring material, but when the thickness of the barrier metal film becomes less than the critical thickness, The original purpose of the barrier metal film is lost, and there is an increase in resistance caused by the WF ₆ gas used in the deposition of tungsten, the conductive film for the main wiring material, an F attack problem in which the WF ₆ gas penetrates into the semiconductor substrate, and Ti. This can lead to problems with the W volcano, where the membrane and WF ₆ react explosively.

In short, since the pitch of the trench is fixed at a constant value and the thickness of the barrier metal film must be maintained above the critical thickness, a method of improving the specific resistance of the conductive film for the main wiring material itself needs to be sought.

Accordingly, the present invention has been made to solve the above-mentioned problems of the prior art, and before forming the conductive film for the main wiring material, an amorphous silicide film or an amorphous TiSiN film is formed to form a nucleus for forming the conductive film for the subsequent main wiring material. It is an object of the present invention to provide a method for forming a wiring of a semiconductor device in which the resistance of the wiring can be reduced by reducing the specific resistance of the conductive film for the main wiring material deposited thereon.

A method for forming a wiring of a semiconductor device according to the present invention includes forming an amorphous silicide film or an amorphous TiSiN film on a semiconductor substrate, and forming a wiring conductive film on the amorphous silicide film or an amorphous TiSiN film.

Forming an adhesive layer on the semiconductor substrate before forming the amorphous silicide film or amorphous TiSiN film, and further comprising forming a barrier metal film on the adhesive layer. The adhesive layer is formed of Ti, and the barrier metal film is formed of any one of TiN, TaN, and TiW.

And forming an ohmic contact layer at an interface between the adhesive layer and the semiconductor substrate after forming the amorphous silicide layer or the amorphous TiSiN layer. The ohmic contact layer is a silicide layer formed by reacting metal ions of the adhesive layer with silicon ions of the semiconductor substrate by a heat treatment process.

* The heat treatment process for forming the ohmic contact layer is performed for 10 to 30 seconds at a temperature of 600 to 900 ℃ by a rapid heat treatment method.

The amorphous silicide film is an amorphous WSix film. The amorphous WSix film is formed by using silica (SiH ₄ ) and WF ₆ as a source gas.

On the other hand, the amorphous silicide film is formed using any one of the chemical vapor deposition method, atomic layer deposition method and physical vapor deposition method at a temperature of 350 to 500 ℃, when using the chemical vapor deposition method, the amorphous silicide film to a thickness of 80 ~ 150Å When the atomic layer deposition method is used, the amorphous silicide film is formed to a thickness of 10 to 100 GPa.

The wiring conductive film is formed by depositing tungsten on the amorphous silicide film or the amorphous TiSiN film, and depositing tungsten using H ₂ and WF ₆ gas using one of chemical vapor deposition and physical vapor deposition.

Hereinafter, with reference to the accompanying drawings will be described a preferred embodiment of the present invention. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various forms, and the scope of the present invention is not limited to the embodiments described below. Only this embodiment is provided to complete the disclosure of the present invention and to fully inform those skilled in the art, the scope of the present invention should be understood by the claims of the present application.

FIG. 1 is a graph measuring the specific resistance (Rs) of tungsten according to the type of under layer.

Referring to FIG. 1, a physical vapor deposition (PVD) tungsten film formed on a Ti / TiN film has a very high specific resistance, whereas a thermal oxidized film and a plasma enhanced nitride film (PE— nitride), a PVD tungsten film formed on a Ti / TiN / WSix film has a low specific resistance value.

Therefore, the present invention forms an amorphous WSix film on the Ti / TiN film, resulting in dispersion of the nucleus upon nucleation of the tungsten, thereby increasing the grain size of the tungsten deposited thereon to form a tungsten film having a low specific resistance, thereby providing resistance to wiring. I want to lower it. The use of an amorphous TiSiN film in place of the amorphous WSix film also results in dispersion of the nucleus during tungsten nucleation.

2A through 2D are cross-sectional views illustrating a wiring forming process of a semiconductor device in accordance with a first embodiment of the present invention.

Referring to FIG. 2A, an adhesive layer 11, a barrier metal film 12, and an amorphous silicide film or an amorphous TiSiN film 13 are sequentially formed on the semiconductor substrate 10.

The adhesive layer 11 is formed of Ti, and the barrier metal film 12 uses any one of TiN, TaN, and TiW. The amorphous silicide film 13 is an amorphous WSix film. Amorphous WSix film 13 is formed by using a silica gas (SiH ₄ ) and WF ₆ as a source gas at a temperature of 350 to 550 ℃, the deposition method is CVD (Chemical Vapor Deposition) method, ALD (Atomic Layer Deposition) It is preferable to use either a method or a PVD (Physical Vapor Deposition) method. In the case of using the CVD method, it is formed to a thickness of 80 to 150 kPa, and in the case of using the ALD method, it is formed to a thickness of 10 to 100 kPa.

The amorphous WSix film 13 serves to bring about dispersion of the nucleus upon subsequent tungsten nucleation and to increase the grain size of the bulk tungsten (bulk W) deposited thereon to reduce the resistivity.

Referring to FIG. 2B, an ohmic contact layer 14 is formed at an interface between the adhesive layer 11 and the semiconductor substrate 10. The ohmic contact layer 14 is formed by performing a heat treatment process. When the adhesive layer 11 is formed of titanium (Ti), the ohmic contact layer 14 is formed of titanium (Ti) ions of the adhesive layer 11 and silicon (Si) ions of the semiconductor substrate 10. The reaction mixture is formed of a titanium silicide (TiSix) film, which is a metal silicide film. The heat treatment process is preferably carried out by a rapid thermal process (RTP) method, and at this time, the process temperature is set to 600 to 900 ° C, and the process time is set to 10 to 30 seconds.

Referring to FIG. 2C, the wiring conductive film 15 is formed on the amorphous silicide film or the amorphous TiSiN film 13.

The wiring conductive film 15 is formed by first forming a tungsten nucleus on the amorphous silicide film or the amorphous TiSiN film 13, and then depositing tungsten by flowing H ₂ and WF ₆ . When tungsten is nucleated, tungsten nuclei are dispersed on the amorphous silicide film or amorphous TiSiN film 13, and tungsten is deposited around the dispersed tungsten nuclei, thereby obtaining a tungsten film having a large grain size. Since the tungsten film having a large grain size has a lower specific resistance than the tungsten film having a small grain size, the resistance of the wiring can be lowered. The tungsten film is formed by depositing tungsten by CVD or PVD method.

Referring to FIG. 2D, the wiring conductive film 15, the amorphous silicide film or the amorphous TiSiN film 13, the barrier metal film 12, the adhesive layer 11, and the ohmic contact layer 14 are patterned and etched on the front surface by an etching process. After the insulating film 16 is formed, the insulating film 16 is planarized so that the wiring conductive film 15 is exposed, thereby completing the wiring forming process according to the first embodiment of the present invention.

3A to 3B are cross-sectional views of a wiring forming process of a semiconductor device according to a second exemplary embodiment of the present invention, and show a case in which the dual damascene process is applied.

Referring to FIG. 3A, the first interlayer insulating film 21, the etch stop film 22, and the second interlayer insulating film 23 are sequentially formed on the semiconductor substrate 20, and the second interlayer insulating film 23 and the etch stop are sequentially formed. A trench 24a is formed in the film 22, and a contact hole 24b is formed in the first interlayer insulating film 21 to form a dual damascene structure 24. Here, the first and second interlayer insulating films 21 and 23 are formed of an oxide film, and the etch stop layer 22 is the first interlayer insulating film during an etching process for forming the trench 24a in the second interlayer insulating film 23. It is formed of a nitride film to prevent the attack of (21).

The adhesive layer 25, the barrier metal film 26, and the amorphous silicide film or the amorphous TiSiN film 27 are sequentially formed on the entire surface including the dual damascene structure 24.

The adhesive layer 25 is formed of Ti, and the barrier metal film 26 uses any one of TiN, TaN, and TiW. The amorphous silicide film 27 is an amorphous WSix film. The amorphous WSix film 27 is formed by using a silica gas (SiH ₄ ) and WF ₆ as a source gas at a temperature of 350 to 550 ° C., and as a deposition method, a chemical vapor deposition (CVD) method and an atomic layer deposition (ALD) method. It is preferable to use either a method or a PVD (Physical Vapor Deposition) method. In the case of using the CVD method, it is formed to a thickness of 80 to 150 kPa, and in the case of using the ALD method, it is formed to a thickness of 10 to 100 kPa.

The amorphous WSix film 27 serves to bring about dispersion of the nucleus upon subsequent tungsten nucleation and to increase the grain size of the bulk tungsten (bulk W) deposited thereon to reduce the resistivity.

Referring to FIG. 3B, an ohmic contact layer 28 is formed at an interface between the adhesive layer 25 and the semiconductor substrate 20. The ohmic contact layer 28 is formed by performing a heat treatment process. When the adhesive layer 25 is formed of titanium, the ohmic contact layer 28 is formed of titanium (Ti) ions of the adhesive layer 25 and silicon (Si) ions of the semiconductor substrate 20. The reaction mixture is formed of a titanium silicide (TiSix) film, which is a metal silicide film. The heat treatment process is preferably carried out by a rapid thermal process (RTP) method, and at this time, the process temperature is set to 600 to 900 ° C, and the process time is set to 10 to 30 seconds.

Referring to FIG. 3C, the wiring conductive film 29 is formed on the amorphous silicide film or the amorphous TiSiN film 27. Next, the wiring conductive film 29 is planarized so that the second interlayer insulating film 23 is exposed to form wiring.

The wiring conductive film 29 is formed by first forming a tungsten nucleus on the amorphous silicide film or the amorphous TiSiN film 27, and then depositing tungsten by flowing H ₂ and WF ₆ . In the nucleation of tungsten, tungsten nuclei are dispersed on the amorphous silicide film or the amorphous TiSiN film 27, and tungsten is deposited around the dispersed tungsten nucleus, thereby obtaining a tungsten film having a large grain size. Since the tungsten film having a large grain size has a lower specific resistance than the tungsten film having a small grain size, the resistance of the wiring can be lowered. The tungsten film is formed by depositing tungsten by CVD or PVD method. Since the damascene structure lacks a gap fill margin, it is preferable to use a CVD method having excellent step coverage characteristics.

This completes the wiring forming step of the semiconductor device according to the second embodiment of the present invention. In the second embodiment, the process of forming the wiring in the dual damascene structure is described, but it is also applicable to the structures such as single damascene, triple damascene, and the like.

4 is a graph comparing the specific resistance (Rs) of the wiring formed by the prior art and the present invention.

Referring to FIG. 4, in the prior art, the specific resistance of the wiring was about 270 ohm / square, but in the case of the present invention, the specific resistance of the wiring can be clearly reduced.

As described above, the present invention forms an amorphous silicide film or TiSiN film before forming the tungsten film, which is a wiring conductive film, resulting in dispersion of nuclei during subsequent nucleation of tungsten and increasing the grain size of tungsten deposited thereon Can reduce the specific resistance. Therefore, the wiring resistance can be lowered and the electrical characteristics of the device can be improved.

Claims (36)

Forming an amorphous silicide film on the semiconductor substrate; And And forming a conductive film for wiring by generating a nuclear dispersion of the metal on the amorphous silicide film and depositing the metal around the nucleus. The method of claim 1, before forming the amorphous silicide film, Forming an adhesive layer on the semiconductor substrate; And And forming a barrier metal film on the adhesive layer. The method of claim 2, wherein the adhesive layer is formed of Ti. The method of claim 2, wherein the barrier metal film is formed of any one of TiN, TaN, and TiW. The method of claim 2, wherein after forming the amorphous silicide film, And forming an ohmic contact layer at an interface between the adhesive layer and the semiconductor substrate. The method of claim 5, wherein the ohmic contact layer is a metal silicide film formed by reacting metal ions of the adhesive layer with silicon ions of the semiconductor substrate by a heat treatment process. 7. The method of claim 6, wherein the metal silicide film is a titanium silicide film. The method of claim 6, wherein the heat treatment step is performed at 600 to 900 ° C. 8. 7. The method of forming a wiring of a semiconductor device according to claim 6, wherein said heat treatment step is performed by a rapid heat treatment method. The method of claim 6, wherein the heat treatment is performed for 10 to 30 seconds. The method of claim 1, wherein the amorphous silicide film is an amorphous WSix film. 12. The method of claim 11, wherein the amorphous WSix film is formed of silicon gas (SiH ₄ ) and WF ₆ as a source gas. The method of claim 1, wherein the amorphous silicide layer is formed by any one of a chemical vapor deposition method, an atomic layer deposition method, and a physical vapor deposition method. The semiconductor element wiring method according to claim 13, wherein when the chemical vapor deposition method is used, the amorphous silicide film is formed to a thickness of 80 to 150 GPa. The semiconductor element wiring formation method according to claim 13, wherein when the atomic layer deposition method is used, the amorphous silicide film is formed to a thickness of 10 to 100 GPa. The method of claim 1, The amorphous silicide layer is formed at a temperature of 350 to 500 ° C. The method for forming a wiring of a semiconductor device according to claim 1, wherein the wiring conductive film is a tungsten film. The method for forming a wiring of a semiconductor device according to claim 1, wherein the wiring conductive film is formed by depositing tungsten on the amorphous silicide film and then depositing tungsten. 19. The method of claim 18 wherein H ₂ and WF ₆ during deposition of tungsten A wiring forming method of a semiconductor device using gas. 19. The method of claim 18, wherein the tungsten deposition process uses any one of chemical vapor deposition and physical vapor deposition. Forming a barrier metal film on the semiconductor substrate; Forming an amorphous TiSiN film on the barrier metal film; And Forming a conductive film for wiring on the amorphous TiSiN film. The method of claim 21, wherein before forming the barrier metal film, And forming an adhesive layer on the semiconductor substrate. 23. The method of claim 22, wherein the adhesive layer is formed of Ti. 22. The method of claim 21, wherein the barrier metal film is formed of any one of TiN, TaN, and TiW. The method of claim 22, wherein after forming the amorphous TiSiN film, And forming an ohmic contact layer at an interface between the adhesive layer and the semiconductor substrate. 26. The method of claim 25, wherein the ohmic contact layer is a metal silicide film formed by reacting metal ions of the adhesive layer with silicon ions of the semiconductor substrate by a heat treatment process. 27. The method of claim 26, wherein the metal silicide film is a titanium silicide film. 27. The method of claim 26, wherein the heat treatment step is performed at 600 to 900 占 폚. 27. The method of claim 26, wherein the heat treatment step is performed by a rapid heat treatment method. 27. The method of claim 26, wherein the heat treatment step is performed for 10 to 30 seconds. The method for forming a wiring of a semiconductor device according to claim 21, wherein the wiring conductive film is a tungsten film. 22. The method of claim 21, wherein the wiring conductive film is formed by depositing tungsten after generating nuclei of tungsten on the amorphous TiSiN film. 33. The method of claim 32 wherein H ₂ and WF ₆ during deposition of tungsten A wiring forming method of a semiconductor device using gas. 33. The method of claim 32, wherein the tungsten deposition process uses any one of chemical vapor deposition and physical vapor deposition. Forming an amorphous silicide film on the semiconductor substrate; And And forming a tungsten film on the amorphous silicide film. Forming an amorphous TiSiN film on a semiconductor substrate; And And forming a tungsten film on the amorphous TiSiN film.

Images