JP2005068456A - Film-forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To directly form a tungsten film with an adequate quality and a low value of specific resistance on an insulating film by annealing a substrate before having the film formed thereon and employing a CVD process with the use of W(CO)<SB>6</SB>. <P>SOLUTION: The film-forming method for forming the tungsten film by supplying W(CO)<SB>6</SB>onto the insulating film formed on a substrate to be treated comprises the first step of heating the substrate to be treated to 150°C or higher and the second step of forming the tungsten film from thermally decomposed W(CO)<SB>6</SB>on the substrate. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for forming a film on a substrate to be processed, and further relates to a method for forming a W film.
[0002]
[Prior art]
In recent years, higher performance and higher integration of semiconductor devices have progressed, and the demand for miniaturization of wiring rules for semiconductor devices has increased.
[0003]
Conventionally, a sputtering method (PVD method) has been often used for forming a metal layer in a manufacturing process of a semiconductor device. However, a chemical vapor deposition method (CVD method) capable of forming a fine pattern having a larger aspect with good coverage due to the recent demand for miniaturization has been widely used in the manufacturing process of semiconductor devices.
[0004]
For example, the W film is deposited by using a raw material such as WF ₆ or WCl ₆ and reducing it with H ₂ , SiH ₄ , or NH ₃ , and forming a W film using a carbonyl raw material. Has also been proposed (see Patent Document 1).
[0005]
[Patent Document 1]
US Pat. No. 4,619,840 [0006]
[Problems to be solved by the invention]
However, for example, when WF ₆ or WCl ₆ is used as a raw material, there is a problem that it is difficult to deposit a W film on an insulating film such as a SiO ₂ film. Therefore, it is necessary to form an adhesion layer such as a TiN film when forming a W film wiring layer, a contact layer, or the like on an insulating film such as a SiO ₂ film.
[0007]
As a result, the number of steps for forming the adhesion layer increases, and there is a problem that the manufacturing cost increases, such as the need for a substrate processing apparatus for forming the adhesion layer. It was difficult to form a W film having a low value.
[0008]
Therefore, in the present invention, the overall problem is to propose a new and useful film forming method that solves the above-described problems.
[0009]
A specific problem of the present invention is that in the film formation method for forming a W film, a moisture removal step is performed before film formation, and a CVD method using W (CO) ₆ is used. A W film having a low specific resistance value is formed directly on the insulating film.
[0010]
[Means for Solving the Problems]
In order to solve the above problems, the present invention
As described in claim 1,
A film forming method for forming a W film by supplying W (CO) ₆ onto an insulating film formed on a substrate to be processed,
A first step of heating the substrate to be processed to 150 ° C. or higher;
A film forming method comprising a second step of forming a W film on the substrate to be processed by thermal decomposition of W (CO) ₆ ;
As described in claim 2,
The film forming method according to claim 1, wherein moisture on the insulating film is removed by the first step.
As described in claim 3,
The film forming method according to claim 1 or 2, wherein the first step is performed under a reduced pressure.
As described in claim 4,
The film forming method according to claim 3, wherein the pressure is 1330 Pa or less,
As described in claim 5,
The film forming method according to claim 1, wherein the first step is performed in an inert gas atmosphere,
As described in claim 6,
The film forming method according to claim 5, wherein the inert gas includes at least one of N ₂ , Ar, or He.
As described in claim 7,
The film forming method according to claim 1, wherein the first step and the second step are continuously performed in a substrate processing container for processing the substrate to be processed. And also
As described in claim 8,
The first step is performed in a first substrate processing container for processing the substrate to be processed, and the second step is further performed in a second substrate processing container for processing the substrate to be processed. The film forming method according to any one of claims 1 to 6, wherein
As described in claim 9,
The film-forming method according to any one of claims 1 to 8, wherein the insulating film is formed by a CVD method.
As described in claim 10,
The film formation method according to any one of claims 1 to 8, wherein the insulating film is formed by a spin coating method by coating.
As described in claim 11,
The problem is solved by the film forming method according to claim 1, wherein the insulating film is a silicon oxide film.
[Action]
According to the present invention, W (CO) ₆ is used as a raw material, this is used as a gas phase raw material, and W (CO) ₆ → W + 6CO is used by using a thermal decomposition reaction.
Thus, the W film can be formed directly on the SiO ₂ film.
[0011]
However, the formed W film has a high specific resistance. This is presumably because the quality of the W film formed due to the influence of moisture on the insulating film is reduced.
[0012]
Therefore, a moisture removing step is provided before the film forming step, the substrate to be processed on which the insulating film is formed is heated to remove moisture adsorbed on the insulating film, and then the W (CO) ₆ described above is used. As a result, a good quality W film having a low specific resistance value can be directly formed on the insulating film.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described below with reference to the drawings.
[First embodiment]
FIG. 1 shows the configuration of a CVD apparatus 10 used in the first embodiment of the present invention.
[0014]
Referring to FIG. 1, a CVD apparatus 10 includes a processing container 11 evacuated by a turbo molecular pump (TMP) 12 and a dry pump (DP) 13, and a substrate that holds a substrate Wf to be processed in the processing container 11. A holding base 11A is provided. A heater 11a is embedded in the substrate holding table 11A, and the substrate to be processed Wf can be heated to a desired temperature.
[0015]
Further, the above processing vessel 11 and shower head 11B is provided to introduce a process gas, wherein the shower head 11B, the W _{(CO) 6} from bubbler 14 for holding a W _{(CO) 6} which is a liquid material Is supplied together with a carrier gas such as Ar as a gas phase raw material through a valve 14A and a line 14B, and a valve 14C provided in the line 14B. W (CO) ₆ supplied in this way is supplied from the shower head 11B to the processing vessel 11 as indicated by an arrow in the figure, and causes a thermal decomposition reaction on the surface of the substrate to be processed. A decomposed W film is deposited on the insulating film formed on the surface of the substrate to be processed Wf.
[0016]
For example, in a reaction using WF ₆ , WCl ₆ as a raw material and H ₂ , SiH ₄ or the like as a reducing agent, a W film is formed on an adhesion layer such as a TiN film, but for example SiO ₂ or the like Although it is very difficult to form a film on the insulating film, in the present invention, it is possible to use W (CO) ₆ as a raw material.
[0017]
Further, a gas line 14D provided with a valve 14d is connected to the shower head 11B. The gas line 14D is connected to a gas supply source (not shown), and can be filled with the inert gas Ar, He, N ₂ or the like to fill the processing vessel 11 with the inert gas. Accordingly, the pressure in the processing vessel 11 can be adjusted using the inert gas.
[0018]
1 is provided with a bypass line 13B that connects the line 14B to a dry pump via a valve 13A. The valve 13A is closed in a normal film forming step. For example, when the carrier gas containing the raw material is flowed out of the processing container 11 before film formation to stabilize the flow rate, or the processing container 11 is The valve 14C is opened when purging, and the valve 14C is closed at the same time. As a result, during such a flow rate stabilization operation, the vapor phase raw material formed by the bubbler 14 is directly discharged to the dry pump 13. As a result, the state of the bubbler 14 can be maintained constant during the deposition process, during the flow rate stabilization operation, and during the purge process.
[0019]
In this embodiment, a carrier gas made of Ar or the like is supplied to the bubbler 14 via the mass flow controller 15 and the valve 15A, thereby causing bubbling. At this time, the concentration of W (CO) ₆ in the vapor phase raw material supplied into the processing vessel 11 can be controlled by controlling the mass flow controller 15 by the system controller 16.
[0020]
Next, a metal film deposition method according to this embodiment will be described with reference to FIGS. 2 (A) and 2 (B).
[0021]
Referring to FIG. 2A, a SiO ₂ film 21A having a thickness of about 100 nm is formed on the surface of the silicon substrate 21, and in the step of FIG. 2A, the silicon substrate 21 is processed into the substrate Wf to be processed. 1 is introduced into the processing container 11 of the CVD apparatus 10 of FIG. 1 via a gate valve (not shown) and placed on the substrate holding table 11A. At this time, the processing vessel 11 is evacuated by the turbo molecular pump (TMP) 12 and the dry pump (DP) 13 and has a pressure of about 6.5 Pa (0.05 Torr). The silicon substrate 21 placed above is heated by the heater 11a embedded in the substrate holding table 11A and held at 400 ° C. for 3 minutes. By providing a step of heating and holding the wafer in the processing vessel 11 thus depressurized, the water adhering to the SiO ₂ film 21A is removed, and the W film formed in the next step The specific resistance value of the W film can be reduced by reducing the impurities. The effect can be obtained when the heating temperature of the wafer is about 150 ° C. or more and the pressure of the processing container 11 is 1330 Pa or less.
[0022]
In the bubbler 14, W (CO) ₆ is held as a metal carbonyl compound at a temperature of 25 ° C.
[0023]
Next, in the process of FIG. 2B, the mass flow controller 15 is controlled by the system controller 16, and Ar carrier gas is supplied to the bubbler 14 held at a temperature of 25 ° C. at a flow rate of 300 SCCM. The pressure in the container 11 is about 20 Pa (0.15 Torr). In the space near the surface of the SiO ₂ film 21A, a supersaturated state of W (CO) ₆ molecules is generated as in the case of a normal thermal CVD method so that the W film 22 covers the SiO ₂ film 21A on the substrate Wf. The film is grown at a deposition rate of about 3 nm / min.
[0024]
Since the W film formed in this way is formed on the clean surface from which the moisture of the SiO ₂ film 21A has been removed as described above, compared with the case where the process of FIG. The specific resistance of the formed W film can be kept low.
[0025]
2A is performed in a vacuum (about 6.5 Pa) in the processing vessel 11, but the same effect can be obtained even when performed in an atmosphere of inert gas such as N ₂ , He, Ar. Is obtained.
[0026]
Further, as shown in the second embodiment below, the process shown in FIG. 2A and the process shown in FIG. 2B can be performed in different processing containers.
[Second Embodiment]
FIG. 3 shows a configuration of the substrate processing apparatus 30 that performs the process shown in FIG.
[0027]
Referring to FIG. 3, the substrate processing apparatus 30 includes a processing container 31 that is evacuated by a turbo molecular pump (TMP) 32 and a dry pump (DP) 33, and holds a substrate to be processed Wf in the processing container 31. A substrate holder 31A is provided. A heater 31a is embedded in the substrate holding table 31A, and the substrate to be processed Wf can be heated to a desired temperature.
[0028]
Further, a shower head 31B for introducing an inert gas processing gas is provided on the processing container 31, and the valve 34C is opened from a gas line 34B connected to the shower head 31B to generate an inert gas. Ar, He, N ₂ or the like is supplied, and the processing vessel 31 can be filled with an inert gas.
[0029]
By using the substrate processing container 30 as described above and further connecting the CVD apparatus 10 and the substrate processing apparatus 30 with the cluster tool apparatus 100 as shown below, the substrate processing apparatus shown in FIG. And the process shown in FIG. 2B in the CVD apparatus 10 can be continuously executed.
[0030]
FIG. 4 shows a configuration of the cluster tool apparatus 100 to which the processing container 11 of the CVD apparatus 10 and the processing container 31 of the substrate processing apparatus 30 are connected.
[0031]
Referring to FIG. 4, the cluster tool device 100 has a polygonal transport container 102, and the transport container 102 is evacuated by an exhaust device (not shown). The cluster tool apparatus 100 is connected to cassette modules 101A and 101B for installing a cassette (not shown) for storing the substrate to be processed Wf, and the substrate to be processed Wf is inserted / removed from the cassette modules 101A and 101B. I do.
[0032]
The CVD apparatus 10 and the substrate processing apparatus 30 are connected to the cluster tool apparatus 100, and the film forming method according to the present invention can be executed as will be described below.
[0033]
First, the substrate Wf to be processed is loaded from the cassette module 101A, and the loaded substrate Wf is transported to the substrate processing container 30 by a transport arm (not shown) installed in the transport container 102.
[0034]
In the substrate processing container 30, the silicon substrate 21 that is a substrate to be processed is mounted on the substrate mounting table 31 </ b> A. Thereafter, in the step shown in FIG. 2A, the valve 34C is opened from the gas line 34B connected to the processing vessel 31, and for example, N ₂ gas, which is an inert gas, is processed from the shower head 31B. The pressure is introduced into the container 31 and the pressure in the processing container becomes 666 Pa. Further, the silicon substrate 21 placed at this time is set to 410 ° C. by the heater 31a embedded in the substrate placing table 31A, and is held in an N ₂ atmosphere for 3 minutes as described above. In this way, by providing a step of heating and holding the wafer in an inert gas atmosphere in the processing vessel 31, the water adhering to the SiO ₂ film 21A is removed, and the wafer is formed in the next step. Impurities in the W film can be reduced to reduce the specific resistance value of the W film.
[0035]
Thereafter, the silicon substrate 21 is transferred to the processing container 11 of the CVD apparatus 10 connected to the transfer container 102 by a transfer arm (not shown) through the transfer container 102. At this time, since the inside of the processing container 102 is evacuated, moisture is not reattached on the SiO ₂ film 21A, and the surface is kept clean and placed on the substrate mounting table 11A. .
[0036]
Next, in the processing container 11, the process of FIG. 2B is performed as in the case of the first embodiment.
[0037]
First, the mass flow controller 15 is controlled by the system controller 16, and Ar carrier gas is supplied to the bubbler 14 held at a temperature of 25 ° C. at a flow rate of 300 SCCM, so that the pressure in the processing container 11 is about 20 Pa ( 0.15 Torr). In the space near the surface of the SiO ₂ film 21A, a supersaturated state of W (CO) ₆ molecules is generated as in the case of a normal thermal CVD method so that the W film 22 covers the SiO ₂ film 21A on the substrate Wf. The film is grown at a deposition rate of about 3 nm / min.
[0038]
Since the W film formed in this way is formed on the clean surface from which the moisture of the SiO ₂ film 21A has been removed as described above, as in the case of the first embodiment described above, FIG. The ratio of the W film formed in the case of the inert gas atmosphere in the step A) and also in the case where the processing is performed in another processing container in the step of FIG. 2A and the step of FIG. Resistance can be kept low.
[Third embodiment]
Next, the specific resistance value of the W film formed according to the present invention is shown in FIG.
[0039]
FIG. 5 shows the specific resistance values of the W films formed by the methods shown in the first and second embodiments as conditions B and C, respectively. For comparison, the specific resistance value when the moisture removal step, which is the step of FIG.
[0040]
Referring to FIG. 5, in the case of the condition A in which the water removal process on the insulating film on the substrate to be processed is not performed, the specific resistance value is as high as 132 Ω-cm. In the case of the conditions B and C, the specific resistance values are suppressed to 42 Ω-cm and 36 Ω-cm, respectively, so that the influence of impurities on the formed W film is eliminated and the specific resistance value is low. It can be seen that the W film can be formed directly on the insulating film.
[0041]
In this embodiment, the case where the W film is formed on the SiO ₂ film is described as an example of the insulating film, but the present invention is not limited to the SiO ₂ film. For example, the same effect can be obtained when another insulating film is formed by CVD or spin coating by coating.
[0042]
For example, a SiC film, a SiCO film, or a SiCO (H) film can be replaced with a SiO ₂ film, and the relative dielectric constant including a SiCN film, a SiN film, or a hydrogenated siloxane film is 3.0 or less. Effective when depositing W films on various low dielectric constant inorganic insulating films, various low dielectric constant organic insulating films such as aromatic polyether films, and inorganic and organic low dielectric constant porous insulating films. It is.
[0043]
Although the present invention has been described with reference to the preferred embodiments, the present invention is not limited to such specific embodiments, and various modifications and changes can be made within the scope described in the claims.
[0044]
【The invention's effect】
According to the present invention, W (CO) ₆ is used as a raw material, this is used as a gas phase raw material, and W (CO) ₆ → W + 6CO is used by using a thermal decomposition reaction.
Thus, the W film can be formed directly on the SiO ₂ film.
[0045]
However, the formed W film has a high specific resistance. This is presumably because the quality of the W film formed due to the influence of moisture on the insulating film is reduced.
[0046]
Therefore, a moisture removing step is performed before the film forming step, the substrate to be processed on which the insulating film is formed is heated to remove moisture adsorbed on the insulating film, and then the W (CO) ₆ described above is used. As a result, a good quality W film having a low specific resistance value can be directly formed on the insulating film.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a CVD apparatus according to the present invention.
FIGS. 2A and 2B are diagrams showing a deposition process of a W film on an insulating film according to the present invention by a CVD method.
FIG. 3 is a diagram showing a configuration of a substrate processing apparatus according to the present invention.
FIG. 4 is a diagram showing a configuration of a cluster tool device according to the present invention.
FIG. 5 is a diagram showing a specific resistance value of a W film.
[Explanation of symbols]
10 CVD apparatus 11, 31 Processing vessel 11A, 31A Substrate holder 11B, 31B Shower head 12, 32 Turbo molecular pump 13, 33 Dry pump 13A, 14A, 14C, 14d, 15A, 34C Valve 13B Bypass line 14 Bubbler 14B, 14D , 34B Line 15 Mass flow controller 16 System controller 21 Silicon substrate 21A SiO ₂ film 22 W film 30 Substrate processing apparatus 100 Cluster tool apparatus 101A, 101B Cassette module 102A Transfer container

Claims (11)

A film forming method for forming a W film by supplying W (CO) ₆ onto an insulating film formed on a substrate to be processed,
A first step of heating the substrate to be processed to 150 ° C. or higher;
A film forming method comprising a second step of forming a W film on the substrate to be processed by thermal decomposition of W (CO) ₆ . The film forming method according to claim 1, wherein moisture on the insulating film is removed by the first step. The film forming method according to claim 1, wherein the first step is performed under a reduced pressure. The film forming method according to claim 3, wherein the pressure is 1330 Pa or less. 3. The film forming method according to claim 1, wherein the first step is performed in an inert gas atmosphere. The film forming method according to claim 5, wherein the inert gas contains at least one of N ₂ , Ar, and He. The film forming method according to claim 1, wherein the first step and the second step are continuously performed in a substrate processing container for processing the substrate to be processed. . The first step is performed in a first substrate processing container for processing the substrate to be processed, and the second step is further performed in a second substrate processing container for processing the substrate to be processed. The film forming method according to any one of claims 1 to 6. The film forming method according to claim 1, wherein the insulating film is formed by a CVD method. The film forming method according to claim 1, wherein the insulating film is formed by a spin coating method by coating. The film forming method according to claim 1, wherein the insulating film is a silicon oxide film.

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