JP3765968B2 - Method for forming electrode structure and method for manufacturing semiconductor device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing an electrode structure having a lower layer film made of polysilicon or amorphous silicon and an upper layer film made of a refractory metal, and a method for manufacturing a semiconductor device having a gate electrode made of the electrode structure.
[0002]
[Prior art]
In the conventional MOS transistor, the gate electrode is formed of a polysilicon film. However, with the progress of miniaturization and high speed of LSI, the demand for lower resistance of the gate electrode of the MOS transistor has been increased.
[0003]
Therefore, in order to reduce the resistance of the gate electrode, a technique using a polymetal gate electrode composed of a laminated film of a lower polysilicon film and an upper refractory metal film has been proposed as the gate electrode, A tungsten film has been proposed as the refractory metal film. When a tungsten film is used as the upper refractory metal film, the resistance value of the gate electrode can be reduced.
[0004]
By the way, between the polysilicon film and the tungsten film, tungsten nitride (WN) is used to prevent diffusion of impurities (for example, B, P, As) introduced into the polysilicon film into the tungsten film. _x ) Or a titanium nitride (TiN) barrier film is required (see, for example, Japanese Patent Application Laid-Open No. 11-261559 or Japanese Patent Application Laid-Open No. 7-235542).
[0005]
FIG. 7A shows a cross-sectional structure of a conventional electrode structure. As shown in FIG. 7A, a gate electrode is formed on a semiconductor substrate 1 with a gate insulating film 2 interposed therebetween, and the gate electrode is formed in order from the lower side, a polysilicon film 3, a nitride film Tungsten (WN _x ) Film 4 and tungsten (W) film 5.
[0006]
Hereinafter, a conventional method for forming an electrode structure will be described with reference to FIGS.
[0007]
First, as shown in FIG. 8A, a polysilicon film 3 is formed on a semiconductor substrate 1 via a gate insulating film 2, and a p-type gate electrode is formed on the polysilicon film 3. When p-type impurities such as boron are doped, n-type impurities such as phosphorus are doped when forming an n-type gate electrode. In order to deposit the tungsten nitride film 4 on the polysilicon film 3, the semiconductor substrate 1 is carried into a chamber in which a tungsten target 7 containing tungsten as a main component is disposed, and then argon gas and nitrogen gas are introduced into the chamber. And a gas discharge are caused in the chamber.
[0008]
In this case, a plasma composed of argon gas and nitrogen gas is generated, and tungsten is blown off from the tungsten target 7 by sputtering of argon ions in the plasma, and the blown tungsten and nitrogen react with each other. As shown in FIG. 8B, a tungsten nitride film 4 is formed on the polysilicon film 3 and a tungsten nitride film 8 is also formed on the surface of the tungsten target 7.
[0009]
Next, as shown in FIG. 8C, the introduction of the nitrogen gas is stopped and only the argon gas is introduced into the chamber, and a discharge is caused in the chamber. In this way, a plasma composed of argon gas is generated, and tungsten is blown off from the tungsten target 9 by sputtering of argon ions in the plasma, and the blown tungsten is deposited on the tungsten nitride film 4. A tungsten film 5 is formed on the tungsten nitride film 4.
[0010]
Next, after forming an impurity layer to be the source or drain of the MOS transistor on the semiconductor substrate 1, a heat treatment of, for example, 750 ° C. or higher is performed to activate the impurity layer, as shown in FIG. 7B. In addition, the nitrogen constituting the tungsten nitride 4 evaporates to change the tungsten nitride film 4 into a tungsten film 5, and a barrier film 6 is formed between the polysilicon film 3 and the tungsten film 5.
[0011]
[Problems to be solved by the invention]
By the way, the barrier film 6 formed between the polysilicon film 3 and the tungsten film 5 is a silicon nitride (SiN) film formed by reacting nitrogen of the tungsten nitride film 4 and silicon of the polysilicon film 3; Alternatively, it is made of a tungsten nitride silicide (WSiN) film formed by the reaction between the tungsten nitride film 4 and the polysilicon film 3. Since both the resistance value of the formed silicon nitride film and the resistance value of the tungsten nitride silicide film are extremely large, the resistance value of the barrier film 6 is also increased, whereby the interface between the polysilicon film 3 and the tungsten film 5 is increased. There is a problem that the resistance becomes high.
[0012]
When the interface resistance between the polysilicon film 3 and the tungsten film 5 increases, the operating speed of the MOS transistor decreases. That is, when the gate electrode performs an AC (alternating current) operation, charging / discharging is repeatedly performed on the distributed capacitance generated in the gate insulating film, so that a current flows through the distributed interface resistance, and the influence of the distributed interface resistance appears. This slows down the operating speed of the MOS transistor.
[0013]
When the operating speed of the MOS transistor is slow, there is a problem that the operating speed of the LSI is slowed and the signal delay time is increased. At the present time when the operation speed of LSI is regarded as important, the operation speed of MOS transistors becomes a big problem even if it degrades by several percent.
[0014]
In order to reduce the interface resistance to such an extent that the delay time of the MOS transistor is not affected, the interface resistance value is 300 Ωμm. ² The following values are required:
[0015]
In view of the above, an object of the present invention is to reduce the interface resistance between a polysilicon film and a refractory metal film.
[0016]
[Means for Solving the Problems]
According to the conventional method, the interface resistance between the polysilicon film and the refractory metal film is increased because of the large thickness of the barrier film, and the thickness of the barrier film is large. This is because the thickness of the tungsten nitride film is large and the amount of nitrogen contained in the tungsten nitride film is large. That is, when the thickness of the tungsten nitride film is large or the amount of nitrogen contained in the tungsten nitride film is large, the silicon nitride film or the tungsten nitride silicide is formed by the reaction between the tungsten nitride film and the polysilicon film. Since the thickness of the film is increased, the resistance value of the barrier film is increased, which is considered to increase the interface resistance between the polysilicon film and the tungsten film.
[0017]
It has also been found that according to the conventional method, it is difficult to deposit a small-sized tungsten nitride film on the polysilicon film with good controllability. The reason is that, in the initial stage of the process of depositing the tungsten film, the tungsten nitride film is formed on the surface of the tungsten target in the process of depositing the tungsten nitride film performed before that, so only argon gas is introduced. However, tungsten nitride blown off from the target tungsten nitride film is deposited on the tungsten nitride film already deposited. Further, in the initial stage of the process of depositing the tungsten film, even if only argon gas is introduced, nitrogen gas remains in the chamber, so that nitrogen is mixed into the tungsten film.
[0018]
The present invention has been made on the basis of the above findings, and specifically, is as follows.
[0019]
The method for forming an electrode structure according to the present invention includes a step of forming a metal nitride film made of a refractory metal nitride on the surface of a first target mainly composed of a refractory metal, and a metal nitride on the surface. The first target on which the film is formed is subjected to the first sputtering using the first inert gas substantially free of nitrogen gas, so that the silicon-containing film containing silicon as a main component can be obtained. A step of depositing a refractory metal nitride thereon to form a first metal film, and a second target containing substantially no refractory metal as a main component; Forming a second metal film by depositing a refractory metal on the first metal film by performing a second sputtering using the inert gas, a silicon-containing film, and a first metal film And a laminated film made of the second metal film And training, and a step of forming an electrode structure composed of a laminated film.
[0020]
According to the method for forming an electrode structure according to the present invention, the first inert gas that does not substantially contain nitrogen gas is used for the first target having a metal nitride film formed on the surface. By performing the first sputtering, a first metal film made of a refractory metal nitride is deposited on the silicon-containing film, so that the thickness of the first metal film can be easily controlled and the first metal film can be easily controlled. The nitrogen concentration in the metal film can be lowered. For this reason, since the thickness of the barrier film formed by the reaction between the first metal film and the silicon-containing film is reduced and the resistance value of the barrier film is reduced, the silicon-containing film and the refractory metal film The interfacial resistance between them becomes low.
[0021]
In the method for forming an electrode structure according to the present invention, the first target and the second target are the same target, and the first inert gas and the second inert gas are the same type of gas. It is preferable.
[0022]
In this case, the first metal film and the second metal film can be formed continuously only by switching the sputtering gas using the same target, so that the throughput is improved.
[0023]
In this case, it is preferable that the step of forming the first metal film and the step of forming the second metal film are performed in the same chamber.
[0024]
In this way, the throughput is further improved.
[0025]
In the method for forming an electrode structure according to the present invention, after the step of forming the second metal film, a third gas using a mixed gas of nitrogen gas and a third inert gas is used for the second target. The method further includes a step of forming a metal nitride film made of a refractory metal nitride on the surface of the second target by performing sputtering, and another electrode structure formed after this electrode structure is formed. In this case, it is preferable to use a second target having a metal nitride film formed on the surface as the first target.
[0026]
In this case, the step of forming the metal nitride film on the surface of the first target can be performed subsequent to the step of forming the second metal film, so that the throughput is improved.
[0027]
The method for forming an electrode structure according to the present invention further comprises a step of heat-treating the electrode structure at a temperature of 750 ° C. or higher after the step of forming the electrode structure. A barrier film having a thickness of 5 nm or less is preferably formed between the film and the first metal film.
[0028]
In this way, the interface resistance between the silicon-containing film and the refractory metal film can be reliably reduced.
[0029]
In the method for forming an electrode structure according to the present invention, the refractory metal is preferably tungsten.
[0030]
A method of manufacturing a semiconductor device according to the present invention includes a step of forming a metal nitride film made of a refractory metal nitride on a surface of a first target mainly composed of a refractory metal, and a metal nitride film on the surface. The polysilicon deposited on the semiconductor region by performing the first sputtering using the first inert gas substantially free of nitrogen gas on the first target formed with Nitrogen gas is substantially not included in the step of forming a first metal film by depositing a refractory metal nitride on the film and the second target mainly composed of the refractory metal. Performing a second sputtering using a second inert gas to deposit a refractory metal on the first metal film to form a second metal film; a polysilicon film; Lamination composed of metal film and second metal film A step of forming a gate electrode made of a laminated film, a step of forming an impurity layer to be a source or a drain by ion implantation of impurities using the gate electrode as a mask, and a heat treatment at a temperature of 750 ° C. or higher. And a step of activating the impurity layer. After the heat treatment, a barrier film having a thickness of 5 nm or less is formed between the polysilicon film and the first metal film.
[0031]
According to the method for manufacturing a semiconductor device according to the present invention, the semiconductor device is manufactured using the method for forming an electrode structure according to the present invention. Even when this heat treatment is performed, the interface resistance between the polysilicon film and the refractory metal film in the gate electrode can be lowered.
[0032]
In the method for manufacturing a semiconductor device according to the present invention, the refractory metal is preferably tungsten.
[0033]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
Hereinafter, as a method for forming an electrode structure according to the first embodiment of the present invention, a method for forming a gate electrode will be described with reference to FIGS. 1 (a) to (c), FIGS. 2 (a) to (c) and FIG. 3. The description will be given with reference.
[0034]
First, as shown in FIG. 1A, after a gate insulating film 11 made of a silicon oxide film is formed on a silicon substrate 10, an amorphous silicon film is deposited on the gate insulating film 11 by a low pressure CVD method. To do.
[0035]
Next, phosphorus (P) ions are implanted into the n-type gate electrode formation region of the amorphous silicon film at an energy of 10 KeV and 6 × 10 6. ¹⁵ cm ^-2 The boron (B) ions are implanted into the p-type gate electrode formation region in the amorphous silicon film at an energy of 5 KeV and 5 × 10 6. ¹⁵ cm ^-2 Doping with a dose amount of Next, the amorphous silicon film doped with phosphorus ions or boron ions is subjected to a heat treatment at a temperature of 750 ° C. for 30 seconds to crystallize the amorphous silicon film to form an n-type or p-type polysilicon film 12. After the formation, the silicon oxide film formed on the surface of the polysilicon film 12 is removed using a hydrofluoric acid-based cleaning liquid.
[0036]
Next, as a preparatory step, as shown in FIG. 3, a mixed gas of argon gas and nitrogen gas is introduced into a chamber in which a tungsten target containing tungsten as a main component is disposed, and a discharge is caused in the chamber. Then, a tungsten nitride film is formed on the surface of the tungsten target.
[0037]
Next, as a wafer replacement process, after the semiconductor substrate (wafer) used in the preparation process is unloaded, as shown in FIG. 1B, the semiconductor substrate 10 on which the polysilicon film 12 is formed is nitrided on the surface. The tungsten target 13 on which the tungsten film 13a is formed is carried into the chamber A in which the tungsten target 13 is disposed.
[0038]
Next, as shown in FIG. 3, argon gas is introduced into the chamber A and a discharge is caused in the chamber A. In this way, a plasma composed of argon gas is generated, and argon ions in the plasma sputter the tungsten nitride film 13a of the tungsten target 13, so that the surface of the polysilicon film 12 is formed as shown in FIG. A first tungsten nitride film 14 is deposited as a first metal film. In this step, the tungsten nitride film 13a formed on the surface of the tungsten target 13 disappears. Thereafter, when the introduction of the argon gas into the chamber A and the discharge in the chamber are continued, the argon ions in the plasma sputter the tungsten target 13, so that the first tungsten nitride as shown in FIG. A tungsten film 15 as a second metal film is deposited on the film 14.
[0039]
Next, as shown in FIG. 3, after stopping the discharge, a mixed gas of argon gas and nitrogen gas is introduced into the chamber A, and then the discharge is caused again, as shown in FIG. As described above, the second tungsten nitride film 16 is formed on the tungsten film 15, and the tungsten nitride film 13 a is also formed on the surface of the tungsten target 13.
[0040]
The polysilicon film 12, the first tungsten film 14, the tungsten film 15, and the second tungsten nitride film 16 described above constitute a gate electrode as an electrode structure. In order to prevent the height of the gate electrode from being too large, the thickness of the laminated film composed of the first tungsten titanium film 14, the tungsten film 15, and the second tungsten nitride film 16 is preferably in the range of 40 nm to 100 nm. . In order to do so, as an example, the thickness of the first tungsten titanium film 14 may be set to 3 nm, the thickness of the tungsten film 15 may be set to 50 nm, and the thickness of the second tungsten nitride film 16 may be set to 5 nm.
[0041]
Note that the tungsten nitride film 13 a formed on the surface of the tungsten target 13 in the step of forming the second tungsten nitride film 16 is used for the step of depositing the first tungsten nitride film 14 on the polysilicon film 12. Can do. That is, the formation process of the second tungsten nitride film 16 and the preparation process described above can be performed in the same process. In this way, throughput is improved.
[0042]
Next, although not shown, the semiconductor substrate 10 is doped with impurities using the gate electrode as a mask to form an impurity layer to be a source or drain, and then, for example, 750 ° C. to activate the impurities. The above heat treatment is performed.
[0043]
As a result, the nitrogen in the first tungsten nitride film 14 diffuses into the tungsten film 15 and the nitrogen in the second tungsten nitride film 16 evaporates. Therefore, as shown in FIG. A tungsten film 17 is formed. Further, the first tungsten nitride film 14 and the polysilicon film 12 react to form a barrier film 18 made of a silicon nitride film or a tungsten nitride silicide film between the tungsten film 17 and the polysilicon film 12. .
[0044]
According to the first embodiment, the tungsten target 13 having the tungsten nitride film 13a formed on the surface thereof is used, and only the argon gas is introduced into the chamber A without introducing the nitrogen gas. 14 is formed, the thickness of the first tungsten nitride film 14 can be easily controlled and the amount of nitrogen contained in the first tungsten nitride film 14 can be reduced. For this reason, since the thickness of the barrier film 18 made of the silicon nitride film or the tungsten nitride silicide film formed by the reaction of the first tungsten nitride film 14 and the polysilicon film 12 is reduced, the resistance of the barrier film 18 is reduced. As a result, the interface resistance between the polysilicon film 12 and the tungsten film 17 is lowered.
[0045]
As described above, in order to reduce the interface resistance between the polysilicon film 12 and the refractory metal film 18 to such an extent that the delay time of the MOS transistor is not affected, the interface resistance is 300 Ωμm. ² Although the following values are required, in the first embodiment, when the thickness of the barrier film 18 is controlled to 5 nm or less, heat treatment at 750 ° C. or higher, for example, heat treatment for 30 seconds at a temperature of 950 ° C. is performed. The interface resistance between the polysilicon film 12 and the refractory metal film 18 is 100 Ωμm ² It can be suppressed to a degree.
[0046]
Further, according to the first embodiment, since the tungsten silicide film is not formed between the polysilicon film 12 and the tungsten film 17, it is possible to prevent the tungsten film 17 from being peeled off.
[0047]
FIG. 4 is a result of an experiment conducted to evaluate the method for forming the electrode structure according to the first embodiment, and N (nitrogen) in a laminated film composed of a lower tungsten nitride film and an upper tungsten film. The results of SIMS analysis are shown.
[0048]
In FIG. 4, the embodiment refers to a laminated film of a first tungsten nitride film (thickness = 5 nm) 14 and a tungsten film (thickness = 40 nm) 15 formed on the polysilicon film by the method described above. The case where it has is shown. Note that the second tungsten nitride film 16 was not deposited on the tungsten film 15 for accurate SIMS analysis. Comparative Example 1 and Comparative Example 2 correspond to the above-described conventional example, and have a laminated film of a tungsten nitride film (thickness = 5 nm) 4 and a tungsten film (thickness = 40 nm) 5 on a polysilicon film. In Comparative Example 1, the tungsten nitride film 4 and the tungsten film 5 are deposited in the same chamber, and in Comparative Example 2, the tungsten nitride film 4 and the tungsten film 5 are deposited in different chambers. It is. Comparative Example 3 shows a case where a tungsten film (thickness = 45 nm) is deposited on a polysilicon film without interposing a tungsten nitride film.
[0049]
The following can be seen from FIG. That is, in Comparative Example 1, a large amount of nitrogen is mixed in the tungsten film. In Comparative Example 2, compared to Comparative Example 1, the nitrogen concentration distribution in the tungsten film becomes steeper and the nitrogen concentration becomes lower, and the thickness and nitrogen concentration of the tungsten nitride film can be controlled well. . However, as described above, the method of Comparative Example 2 has a problem in that it requires two chambers including a chamber for depositing tungsten nitride and a chamber for depositing a tungsten film.
[0050]
On the other hand, in the present embodiment, the first tungsten nitride 14 and the tungsten film 15 can be deposited in one chamber. The step of depositing the first tungsten nitride film 14 uses the tungsten film 13 having the tungsten nitride film 13a formed on the surface and introduces only argon gas into the chamber A. Therefore, the first tungsten nitride film 14 is deposited. The film thickness of the film 14 is determined in a self-aligned manner based on the thickness of the tungsten nitride film 13a, and the nitrogen concentration in the first tungsten nitride film 14 is lower than those in the first and second comparative examples.
[0051]
(Second Embodiment)
Hereinafter, a method for fabricating a semiconductor device according to the second embodiment of the present invention will be described with reference to FIGS. 5 (a) and 5 (b) and FIGS. 6 (a) and 6 (b).
[0052]
First, as shown in FIG. 5A, a silicon oxide film 21 that becomes a gate insulating film is formed on a semiconductor substrate 20 made of, for example, a silicon substrate, and then a polysilicon film 22 is formed on the silicon oxide film 21. To deposit.
[0053]
Next, a first tungsten nitride film 24, a tungsten film 25, and a second tungsten nitride film 26 are sequentially deposited on the polysilicon film 22 by the same method as in the first embodiment, and the first A laminated film composed of the tungsten nitride film 24, the tungsten film 25, and the second tungsten nitride film 26 is formed, and then a hard mask 27 for forming a gate electrode composed of a silicon nitride film is formed on the laminated film. To do.
[0054]
Next, as shown in FIG. 5B, the laminated film is etched using a hard mask 27 to form a gate electrode made of the laminated film. Next, after doping the semiconductor substrate 20 with impurities using the gate electrode as a mask to form the low concentration impurity layer 28, a silicon nitride film is deposited over the entire surface of the semiconductor substrate 20, and then the silicon nitride film As shown in FIG. 6A, a sidewall 29 is formed on the wall surface of the gate electrode by anisotropic etching. Next, the semiconductor substrate 20 is doped with impurities using the gate electrode and the sidewall 29 as a mask to form a high concentration impurity layer 30.
[0055]
Next, the semiconductor substrate 20 is subjected to heat treatment for 30 seconds at a temperature of 750 ° C. or higher, for example, 975 ° C., to activate the low concentration impurity layer 28 and the high concentration impurity layer 30. In this case, since the nitrogen of the first tungsten nitride film 24 and the second tungsten nitride film 26 diffuses into the tungsten film 25, one tungsten film 31 is formed as a whole and the first tungsten nitride film 24 and the polysilicon film 22 react to form a barrier film 32 made of a silicon nitride film or a tungsten nitride silicide film between the tungsten film 31 and the polysilicon film 22.
[0056]
According to the second embodiment, since the thickness of the barrier film 32 formed between the polysilicon film 22 and the tungsten film 31 after the heat treatment at 750 ° C. or higher can be suppressed, the polysilicon film 22, the tungsten film 31, Since the interfacial resistance between the MOS transistors can be lowered, the operating speed of the MOS transistor can be prevented from being lowered. Further, it is possible to prevent the tungsten film 31 from being peeled off due to the formation of the tungsten silicide layer.
[0057]
In the first and second embodiments, the tungsten film is used as the refractory metal film, but a molybdenum (Mo) film or the like may be used instead.
[0058]
Further, as the semiconductor substrate, an SOI substrate may be used instead of the silicon substrate.
[0059]
【The invention's effect】
According to the electrode structure forming method of the present invention, the thickness of the first metal film formed between the silicon-containing film and the second metal film (refractory metal film) in the electrode structure is controlled to be thin. In addition, since the nitrogen concentration of the first metal film can be lowered, the interface resistance between the silicon-containing film and the refractory metal film can be lowered.
[0060]
In addition, according to the method for manufacturing a semiconductor device of the present invention, the polysilicon film and the refractory metal film in the gate electrode can be formed even when heat treatment at 750 ° C. or higher is performed to activate the impurity layer serving as the source or drain. The interface resistance between them can be lowered. Therefore, the delay time of the MOS transistor can be reduced and the operation speed of the MOS transistor can be improved.
[Brief description of the drawings]
FIGS. 1A to 1C are cross-sectional views showing respective steps of a method for forming an electrode structure according to a first embodiment.
FIGS. 2A to 2C are cross-sectional views showing respective steps of a method for forming an electrode structure according to the first embodiment. FIGS.
FIG. 3 is a sequence diagram showing the relationship between the type of gas introduced into the chamber and discharge in the first embodiment.
FIG. 4 is a result of an experiment conducted for evaluating the method of forming the electrode structure according to the first embodiment, and N (nitrogen) in a laminated film composed of a lower tungsten nitride film and an upper tungsten film; It is a figure which shows the SIMS analysis result of.
FIGS. 5A and 5B are cross-sectional views illustrating respective steps of a semiconductor device manufacturing method according to a second embodiment.
6A and 6B are cross-sectional views illustrating respective steps of a method for manufacturing a semiconductor device according to a second embodiment.
7A is a cross-sectional view of an electrode structure according to a conventional example, and FIG. 7B is a cross-sectional view when a heat treatment at 750 ° C. or higher is performed on the electrode structure according to the conventional example.
FIGS. 8A to 8C are cross-sectional views showing respective steps of a method for forming an electrode structure according to a conventional example.
FIG. 9 is a sequence diagram showing the relationship between the type of gas introduced into a chamber and discharge in a conventional example.
[Explanation of symbols]
A chamber
10 Semiconductor substrate
11 Gate insulation film
12 Polysilicon film
13 Tungsten target
13a Tungsten nitride film
14 First tungsten nitride film
15 Tungsten film
16 Second tungsten nitride film
17 Tungsten film
18 Barrier film
20 Semiconductor substrate
21 Gate insulation film
22 Polysilicon film
24 First tungsten nitride film
25 Tungsten film
26 Second tungsten nitride film
27 Hard Mask
28 Low-concentration impurity layer
29 sidewall
30 High concentration impurity layer
31 Tungsten film
32 Barrier film

Claims (8)

Forming a metal nitride film made of the refractory metal nitride on the surface of the first target mainly composed of the refractory metal;
The first target having the metal nitride film formed on the surface is subjected to first sputtering using a first inert gas that is substantially free of nitrogen gas, so that silicon is mainly used. Depositing the refractory metal nitride on the silicon-containing film as a component to form a first metal film;
By performing second sputtering using a second inert gas substantially free of nitrogen gas on the second target containing the refractory metal as a main component, the first metal film Depositing the refractory metal thereon to form a second metal film;
And a step of patterning a laminated film made of the silicon-containing film, the first metal film, and the second metal film to form an electrode structure made of the laminated film. Method for forming structure. The first target and the second target are the same target, and the first inert gas and the second inert gas are the same kind of gas. A method for forming an electrode structure according to claim 1. 3. The method for forming an electrode structure according to claim 2, wherein the step of forming the first metal film and the step of forming the second metal film are performed in the same chamber. After the step of forming the second metal film, the second target is subjected to a third sputtering using a mixed gas of nitrogen gas and a third inert gas, thereby the second target. Further comprising a step of forming a metal nitride film made of the refractory metal nitride on the surface of the target,
When forming another electrode structure formed after the electrode structure, the second target having the metal nitride film formed on the surface thereof is used as the first target. The method for forming an electrode structure according to claim 1. After the step of forming the electrode structure, further comprising a step of performing a heat treatment on the electrode structure at a temperature of 750 ° C. or higher,
The electrode structure according to claim 1, wherein a barrier film having a thickness of 5 nm or less is formed between the silicon-containing film and the first metal film after the heat treatment. Forming method. The method for forming an electrode structure according to claim 1, wherein the refractory metal is tungsten. Forming a metal nitride film made of the refractory metal nitride on the surface of the first target mainly composed of the refractory metal;
By performing first sputtering using a first inert gas substantially free of nitrogen gas on the first target having the metal nitride film formed on the surface thereof, the semiconductor region Depositing the refractory metal nitride on the polysilicon film deposited thereon to form a first metal film;
By performing second sputtering using a second inert gas substantially free of nitrogen gas on the second target containing the refractory metal as a main component, the first metal film Depositing the refractory metal thereon to form a second metal film;
Patterning a laminated film composed of the polysilicon film, the first metal film, and the second metal film to form a gate electrode composed of the laminated film;
Using the gate electrode as a mask to implant an impurity to form an impurity layer to be a source or drain;
Providing a heat treatment at a temperature of 750 ° C. or higher to activate the impurity layer,
A method of manufacturing a semiconductor device, wherein a barrier film having a thickness of 5 nm or less is formed between the polysilicon film and the first metal film after the heat treatment. 8. The method of manufacturing a semiconductor device according to claim 7, wherein the refractory metal is tungsten.

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