Method and apparatus for forming metal film of molybdenum

Abstract

To provide a technique capable of forming a metal film of molybdenum having a small specific resistance.SOLUTION: When a metal film of molybdenum is formed on a substrate, a step of forming a metal base film of tungsten on the substrate and a step of forming the metal film on the metal base film are performed. By forming the metal film of molybdenum on the metal base film of tungsten, the grain size of molybdenum is increased, and the metal film of molybdenum having a small specific resistance can be formed.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a method and apparatus for depositing molybdenum metal films. [Background technology]

[0002] Copper has traditionally been used as a wiring material in semiconductor manufacturing equipment, but as conductor devices become increasingly miniaturized, the problem of increased resistivity due to the thin-line effect has become apparent in copper wiring. For this reason, we are considering replacing copper with wiring materials that are less susceptible to the thin-line effect than copper. As a method for forming a low-resistance thin film, Patent Document 1 describes a technique for forming a low-resistance tungsten film by stacking a tungsten liner layer and a tungsten film in the manufacture of electronic devices. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2023-516859 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a technique that can form a molybdenum metal film with low resistivity. [Means for solving the problem]

[0005] The present disclosure provides: 1. A method for depositing a molybdenum metal film on a substrate, comprising: forming a tungsten metal underlayer on the substrate; and forming the metal film on the metal underlayer. [Effects of the Invention]

[0006] According to the present disclosure, it is possible to form a molybdenum metal film having low resistivity. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a first process chart showing a first embodiment of a method for forming a molybdenum metal film. [Figure 2] FIG. 1 is a first characteristic diagram showing the relationship between the film thickness and resistivity of a molybdenum film. [Figure 3] FIG. 2 is a second characteristic diagram showing the relationship between the film thickness and resistivity of a molybdenum film. [Figure 4] 1 is a first grain map of a molybdenum film. [Figure 5] 1 is a second grain map of a molybdenum film. [Figure 6] 1 is a grain map of a tungsten film. [Figure 7] 1 is a first XRD crystal structure analysis result of a tungsten film. [Figure 8] FIG. 10 is a third characteristic diagram showing the relationship between the film thickness of a laminated film of a tungsten film and a molybdenum film and the resistivity of the laminated film. [Figure 9] FIG. 4 is a fourth characteristic diagram showing the relationship between the film thickness of a laminated film of a tungsten film and a molybdenum film and the resistivity of the laminated film. [Figure 10] FIG. 5 is a fifth characteristic diagram showing the relationship between the film thickness of a laminated film of a tungsten film and a molybdenum film and the resistivity of the laminated film. [Figure 11] FIG. 6 is a second process chart showing a second embodiment of the method for forming a molybdenum metal film. [Figure 12] FIG. 6 is a sixth characteristic diagram showing the relationship between the film thickness and resistivity of a molybdenum film. [Figure 13] FIG. 7 is a seventh characteristic diagram showing the relationship between the film thickness and resistivity of a molybdenum film. [Figure 14] 2 shows the second XRD crystal structure analysis result of the tungsten film. [Figure 15] FIG. 11 is an eighth characteristic diagram showing the relationship between the film thickness of a laminated film of a tungsten film and a molybdenum film and the resistivity of the laminated film. [Figure 16] FIG. 10 is a third process diagram showing the process of forming a tungsten film and a molybdenum film. [Figure 17] FIG. 1 is a plan view showing an example of the configuration of a film forming apparatus for forming a molybdenum film. [Figure 18] 1 is a vertical cross-sectional side view showing an example of the configuration of a first processing module that forms a tungsten film. [Figure 19] FIG. 10 is a vertical cross-sectional side view showing an example of the configuration of a second processing module that forms a molybdenum film. [Figure 20] FIG. 10 is a fourth process diagram showing the process of forming a tungsten film and a molybdenum film. [Figure 21] FIG. 10 is a plan view showing another example of the configuration of a film forming apparatus for forming a molybdenum film. DETAILED DESCRIPTION OF THE INVENTION

[0008] The present inventors have been investigating the use of molybdenum (Mo) as an alternative wiring material to copper (Cu) in semiconductor devices. Mo is a material that is less susceptible to the thin-line effect than Cu or tungsten (W). Therefore, even when the electrode line width is reduced, the influence of the thin-line effect is small, and it is expected that an increase in resistivity can be suppressed. On the other hand, W also has an advantage of having a smaller grain size than Mo. Generally, there is a relationship between grain size and resistivity: if the grain size can be increased, the number of crystal grain boundaries decreases and the resistivity decreases. Therefore, with Mo, the challenge in suppressing an increase in resistivity is to increase the grain size as much as possible.

[0009] For example, when the film thickness of Mo is 10 nm or more, the resistivity is similar to that of W, but as the Mo film becomes thinner, the effect of its small grain size becomes greater. Therefore, we investigated a technology to reduce the resistivity of Mo even in thin films by increasing the Mo grain size. We then focused on increasing the Mo grain size by using an underlayer formed on the lower side of the Mo film, and found that the Mo grain size could be increased by using W, which has a larger grain size than Mo, as the underlayer. Thus, the present disclosure involves forming a tungsten (W) metal base film on a semiconductor wafer (hereinafter referred to as "wafer"), which is a substrate, and then forming a molybdenum (Mo) metal film on this metal base film.

[0010] First Embodiment Next, a first embodiment of the method for forming a Mo metal film according to the present disclosure will be described. Fig. 1(a) shows a silicon oxide film (SiO2 film) 11 formed on a wafer 10 (see Fig. 18 described later) which is a substrate. The SiO2 film 11 has recesses (not shown) that form trenches, via holes, etc.

[0011] Then, as shown in FIG. 1(b), a step of forming a metal base film 12 of W on the wafer 10 on which the SiO2 film 11 has been formed is carried out. This W metal underlayer 12 can be formed by, for example, sputtering, vapor deposition, ALD (Atomic Layer Deposition), or CVD (Chemical Vapor Deposition). This W metal underlayer 12 is formed so as to cover, for example, the entire bottom and side surfaces of the recess, but may also be formed only on the bottom surface or only on the side surfaces of the recess formed in the SiO2 film 11. The thickness of the W metal underlayer 12 is set to a value within the range of 1 to 5 nm, as will be described later.

[0012] Next, as shown in FIG. 1(c), a step of forming a metal film 13 of Mo on the metal base film 12 of W is carried out. This Mo metal film 13 can be formed by, for example, sputtering, ALD, or CVD. The Mo metal film 13 is formed so as to fill recesses formed in the SiO2 film 11, for example, and its thickness is selected appropriately depending on the device structure, such as the depth of the recesses. In the following description, the W metal base film 12 will be referred to as the "W film 12," and the Mo metal film 13 will be referred to as the "Mo film 13."

[0013] In this way, when forming the Mo film 13 on the wafer 10 on which the SiO2 film 11 is formed, forming the W film 12 as an underlayer film for the Mo film 13 can reduce the resistivity of the Mo film 13. Hereinafter, this will be described with reference to data on the resistivity of the Mo film 13. FIG. 2 is a characteristic diagram showing the resistivity of the Mo film 13 for the W film 12 and Mo film 13 formed under ex-situ conditions. The thickness of the W film 12 was set to 5 nm, and the thickness of the Mo film 13 was varied within the range of 5 nm to 15 nm. The horizontal axis in the diagram represents the thickness (nm) of the Mo film 13, and the vertical axis represents the resistivity (μΩcm) of the Mo film 13. The resistivity of the Mo film 13 was calculated by measuring the resistance of the laminated film of the W film 12 and the Mo film 13, and then using the measurement results to calculate the resistivity of the W film 12 and the thickness of the Mo film 13. Unless otherwise specified, the resistivity of the Mo film 13 in the following examples was also calculated using the same method.

[0014] Here, forming a film under ex-situ conditions means that after a W film 12 is formed on a wafer 10 in a first processing module, the wafer 10 is temporarily transferred from a vacuum atmosphere to an atmospheric atmosphere. Next, in a second processing module, a Mo film 13 is formed on the W film 12 on the wafer 10. In the experiment, the first processing module and the second processing module may be different modules or may be the same module. The formation of the W film 12 and the Mo film 13 under ex-situ conditions was performed to confirm the effect of transferring the wafer 10, on which the W film 12 has been formed, into an atmospheric atmosphere.

[0015] Example 1-1 is an example in which a W film 12 is formed by sputtering on a wafer 10 on which a SiO2 film 11 has been formed in advance and on which a recess has been formed, and then a Mo film 13 is formed by sputtering, and this is plotted as a hollow diamond (◇) in Figure 2. The SiO2 film is, for example, a thermal oxide film, which is formed by heating the silicon wafer in an oxygen atmosphere and oxidizing the surface of the silicon wafer. 。An example of the configuration of a sputtering apparatus for carrying out the sputtering method will be described later with reference to FIG. 18. The deposition conditions for the W film 12 carried out using this apparatus are deposition temperature: room temperature, pressure: 2.3×10 -1 The deposition conditions for the Mo film 13 were: deposition temperature: room temperature, pressure: 6.2 × 10 -2 It was Pa.

[0016] In Examples 1-2 and 1-3, a W film 12 was formed by sputtering on a wafer 10 on which a SiO2 film 11 had been formed and a recessed portion had been formed, and then a Mo film 13 was formed by ALD. In Example 1-2, MoO2Cl2 gas (first Mo-containing gas) was used as the source gas for the Mo film 13, and this is plotted as a white square (□) in Figure 2. In Example 1-3, a gas containing a molybdenum halide that does not contain oxygen (second Mo-containing gas) was used as the source gas for the Mo film 13, and this is plotted as a white circle (◯) in Figure 2. The SiO2 film 11 and W film 2 were formed in the same manner as in Example 1-1. An example of the configuration of a film formation module for performing the ALD method will be described later with reference to Figure 19. The deposition conditions for the Mo film 13 performed using this deposition module were a deposition temperature of 580° C. and a pressure of 5.33 kPa in Example 1-2, and a deposition temperature of 530° C. and a pressure of 1.33 kPa in Example 1-3.

[0017] 2, a comparative example 1-1 is plotted by a black triangle (▲) in which only a Mo film 13 is formed on a wafer 10 on which a SiO film 11 has been formed in advance and a recess has been formed, without forming a W film 12. Comparative example 1-1 is an example in which a Mo film 13 is formed by sputtering, and the SiO film 11 and Mo film 13 were formed in the same manner as in Example 1-1.

[0018] 2, it was confirmed that the resistivity of the Mo film 13 in Examples 1-1, 1-2, and 1-3 was lower than that in Comparative Example 1-1. In particular, under the condition of a Mo film thickness of 5 nm, where the influence of the thin wire effect is significant, the resistivity of each Example was significantly lower than that of Comparative Example 1-1. Furthermore, although the thin wire effect was observed in each of Examples 1-1, 1-2, and 1-3, the increase in resistivity with decreasing film thickness was small, and in particular, the change in resistivity in Example 1-3 was extremely small. Furthermore, when the thickness of the Mo film 13 was approximately 10 nm, the resistivity was slightly above 10 μΩcm in Example 1-1, but was below 10 μΩcm in Examples 1-2 and 1-3, which was significantly lower than that of Comparative Example 1-1.

[0019] Furthermore, it was confirmed that the resistivity of the Mo film 13 in Example 1-3 was further reduced compared to Examples 1-1 and 1-2. The reason for this is presumably that the second Mo-containing gas used in Example 1-3 is a gas containing a halogen but not oxygen, and exhibits the effect of etching the Mo oxide film while suppressing Mo oxidation. In other words, under ex-situ conditions, the wafer 10 on which the W film 12 is formed is temporarily transferred into the air atmosphere, so the surface of the W film 12 is oxidized. In Example 1-3, during the formation of the Mo film 13, the oxide layer formed on the surface of the W film 12 is etched by the halogen contained in the second Mo-containing gas, and the Mo film 13 is formed while removing the oxide layer.

[0020] In particular, because the second Mo-containing gas does not contain oxygen, oxidation of the W film 12 after the oxide layer is removed and the Mo film 13 itself to be deposited are also suppressed. In contrast, in Example 1-1, the Mo film 13 is deposited on the oxide layer, and the presence of the oxide layer is presumably responsible for the increased resistivity of the Mo film 13 compared to Example 1-3. Furthermore, the first Mo-containing gas (MoO2Cl2 gas) used in Example 1-2 contains a halogen and has the ability to etch and remove the oxide layer on the surface of the W film 12. On the other hand, because the first Mo-containing gas contains oxygen, the deposited Mo film 13 may contain oxygen, which is thought to result in a higher resistivity compared to Example 1-3.

[0021] 3 is a characteristic diagram showing the resistivity of the Mo film 13 for the W film 12 and Mo film 13 formed under in-situ conditions. The thickness of the W film 12 was set to 5 nm, and the thickness of the Mo film 13 was varied within the range of 5 nm to 15 nm. In the diagram, the horizontal axis represents the thickness (nm) of the Mo film 13, and the vertical axis represents the resistivity (μΩcm) of the Mo film 13.

[0022] Deposition under in-situ conditions refers to depositing a W film 12 on a wafer 10 in a first processing module, then transferring the wafer 10 to a second processing module in a vacuum atmosphere, and depositing a Mo film 13 on the W film 12 on the wafer 10 in the second processing module. This also includes a case where the first processing module and the second processing module are a common module, and the Mo film 13 is deposited in the same processing module after the W film 12 is deposited.

[0023] In Fig. 3, Example 1-4 is plotted as an open triangle (△) and Comparative Example 1-1 as a filled triangle (▲). Example 1-4 is an example in which a W film 12 is formed by sputtering on a wafer 10 on which a SiO2 film 11 has been formed in advance and on which a recess has been formed, and then a Mo film 13 is formed by sputtering. The formation of the SiO2 film 11, the W film 12 by sputtering, and the Mo film 13 is the same as in Example 1-1. Comparative Example 1-1 is as described above. 3, it is confirmed that the resistivity of the Mo film 13 in Example 1-4 is significantly lower than that in Comparative Example 1-1. In particular, when the thickness of the Mo film 13 is about 5 nm, the resistivity in Example 1-4 is about 8.8 μΩcm, which is significantly lower than that of Comparative Example 1-1, which is about 27.5 μΩcm.

[0024] Furthermore, it was found that in Example 1-4, the degree of increase in resistivity with decreasing film thickness was extremely small. Furthermore, comparing Example 1-1, Example 1-2, Example 1-3, and Example 1-4, it was found that the resistivity of the Mo film 13 in Example 1-3 and Example 1-4 was similarly low. The reason for this is presumably that, since the W film 12 and the Mo film 13 were formed in situ in Example 1-4, the formation of an oxide layer on the W film 12 was suppressed, thereby suppressing the increase in resistivity. Therefore, it is believed that the resistivity of the Mo film 13 can be further reduced by adopting a film formation method that suppresses the formation of an oxide layer between the W film 12 and the Mo film 13 (selecting an oxygen-free Mo-containing gas or forming the film under in situ conditions), as in Examples 1-3 and 1-4.

[0025] 2 and 3, it can be seen that when forming a Mo film 13 on a wafer 10 having a SiO2 film 11 formed thereon, forming a W film 12 as an underlayer for the Mo film 13 can significantly reduce the resistivity of the Mo film 13. In particular, in Examples 1-3 and 1-4, even when the Mo film 13 is as thin as 5 nm, it achieves a resistivity of 10 μΩcm or less, making it effective as a wiring material.

[0026] The reason for the decrease in resistivity of the Mo film 13 is understood as follows. One reason is that by forming the Mo film 13 on the underlayer of the W film 12, the grain size of the Mo film 13 can be increased by two to three times. This is presumably because the Mo film 13 grows under the influence of W, which has a larger grain size than Mo. As mentioned above, there is a correlation between grain size and resistivity, and by forming a Mo film 13 with a large grain size, the resistivity of the Mo film 13 can be decreased.

[0027] 4, 5, and 6 each show a crystal grain map analyzed using a TEM (Transmission Electron Microscope). In these crystal grain maps, grains with an orientation difference of 5° or less are defined as the same grain, and the same grains are color-coded by being painted in the same color (the original is in color). FIG. 4 shows the crystal grain map of Example 1-2 (W film: 5 nm, Mo film: 13 nm), FIG. 5 shows the crystal grain map of Example 1-3 (W film: 5 nm, Mo film: 14 nm), and FIG. 6 shows the crystal grain map of Reference Example 1-1. Reference Example 1-1 is a wafer 10 on which a 5-nm W film 12 is formed by sputtering on a wafer 10 on which a SiO2 film 11 has been formed.

[0028] According to these crystal grain maps, the average grain size of the metal crystals contained in each film was 68.9 nm in Example 1-2, 54.4 nm in Example 1-3, and 25.5 nm in Reference Example 1-1. It can be seen that the average grain size in Examples 1-2 and 1-3 is more than twice as large as that of W in Reference Example 1-1. As described above, the grain size of the Mo film 13 is larger in the laminated film (FIGS. 4 and 5) of the W film 12 and the Mo film 13 than in the single W film (FIG. 6). Furthermore, in FIGS. 4 and 5, no boundary separating the W film 12 and the Mo film 13 from each other is observed, and the average grain size is larger than that of the single W film. From this, it is presumed that by forming the Mo film 13 on the W film 12, the grains of the W film 12 grow together with the grains of the Mo film 13. However, as will be described later, it is believed that the increase in the grain size of the W film 12 is little influenced by the annealing effect caused by exposure to a high film-forming temperature (e.g., 580°C) during the formation of the Mo film 13.

[0029] Furthermore, for Example 1-3 (W film: 5 nm, Mo film: 14 nm), particle size analysis of the Mo film 13 using TEM revealed that the average grain size was 48 nm, which is approximately twice the grain size of the Mo film 13 without the W film 12 formed as an undercoat.

[0030] Furthermore, when Examples 1-3 were imaged by TEM, it was confirmed that the SiO2 film 11, W film 12, and Mo film 13 formed a layered structure, and that the Mo crystals and W crystals were approximately the same size (not shown). From this result, it is inferred that Mo is integrated with W, and that Mo grains grow on the underlying W grains. Note that the layered structure of SiO2 11, W film 12, and Mo film 13 was also confirmed by a separate analysis of the elements contained in each film using EDX (Energy Dispersive X-ray spectroscopy). From these results, it can be understood that by forming the W film 12 as an underlayer for the Mo film 13, the grains of W affect the growth of Mo, increasing the grain size of the Mo film 13, and as a result, reducing the resistivity.

[0031] Another reason is that the crystal structure of the W film 12 also contributes to the reduction in the resistivity of the Mo film 13. Figure 7 shows the results of crystal structure analysis obtained by XRD (X-ray diffraction) of a W film (5 nm thick) formed by sputtering on a wafer 10 with an SiO2 film 11. In the figure, the horizontal axis represents the diffraction angle 2θ, and the vertical axis represents intensity (CPS: counts per second). W film crystal structures are known to have a stable body-centered cubic structure (α phase) and a metastable A15 structure (β phase). The diffraction angle of the α phase is shown by the dashed line, and the diffraction angle of the β phase is shown by the solid line.

[0032] As shown in this figure, the W film formed on the SiO2 film 11 by the sputtering method has a peak corresponding to the diffraction angle of the α phase, but also has many peaks corresponding to the diffraction angle of the β phase, indicating that the W film contains a large amount of β phase crystals. As mentioned above, the grain size of the Mo film 13 increases when the W film 12 is used as an underlayer, and this is presumably due to the fact that the W film 12 grows with a β-phase orientation. For example, it is presumed that forming the Mo film 13 on the W film 12, which has a crystalline structure with a high β-phase content, increases the grain size of the Mo film 13 and reduces its resistivity.

[0033] As will be described in the second embodiment, it has been confirmed that in a configuration in which a W film 12 is laminated on a titanium nitride (TiN) film, the crystalline phase contained in the W film 12 is primarily the α phase. Therefore, it is presumed that laminating the W film 12 on the SiO film 11 can form a W film 12 with a high β phase content. In this example, a thermally oxidized SiO film is used, but the deposition method for the SiO film 11 and the W film 12 has little effect on the β phase content in the W film 12. For example, it is believed that the β phase content in the W film 12 can be increased simply by depositing a W film on a film containing silicon (Si) and oxygen (SiO film 11) by the aforementioned sputtering method. The SiO film 11 may be deposited by, for example, a CVD method or an ALD method using SiH gas and O gas as raw materials. Alternatively, a spin coating method may be used in which a polysilazane solution is supplied to a rotating wafer 10 and then the wafer 10 is heated to form the SiO film 11.

[0034] As explained above, Figures 4 to 7 confirm that a Mo film 13 with a large grain size was obtained by the ALD method using two types of raw materials. These experimental results show a correlation between the grain size and resistivity of the Mo film 13. Therefore, it is believed that the formation of the W film 12 has the effect of increasing the grain size not only in Mo films 13 formed by the ALD method but also in Mo films 13 formed by the sputtering method. It is generally known that grain size increases with annealing, but the Mo film is formed at room temperature with the sputtering method. Therefore, when the Mo film 13 is formed on the W film 12 as an underlayer, it is believed that the grain size of the Mo film 13 is not significantly affected by the heat generated during film formation.

[0035] Therefore, in order to confirm the effect of annealing on the stacked film of the W film 12 and the Mo film 13 of Example 1-3, annealing was performed at 850°C for 2 minutes. As a result, no significant change in grain size was observed before and after annealing. In contrast, in the method of the present disclosure, the grain size of the Mo film 13 was already large when the Mo film 13 was formed, so it is presumed that the effect of annealing on growing the grain size is small.

[0036] As described above, the method of the present disclosure can form a Mo film 13 with low resistivity. However, when a stacked film of a W film 12 and a Mo film 13 is actually used in a semiconductor device, the resistivity of the entire stacked film becomes an issue. Therefore, the resistivity of the stacked film of Examples 1-4 was measured. The results are shown in FIG. 8. In the figure, the horizontal axis represents the total thickness (nm) of the W film 12 and the Mo film 13 (stacked film), and the vertical axis represents the resistivity (μΩcm) of the stacked film. The stacked films of Examples 1-4 were formed with a W film 12 thickness of 5 nm and Mo film 13 thicknesses of 5 nm, 10 nm, and 15 nm. In FIG. 8, Examples 1-4 are plotted with open triangles (△), and Comparative Example 1-1 is plotted with filled triangles (▲).

[0037] In Figure 8, comparing Comparative Example 1-1 and Example 1-4, it can be seen that when the film thickness of the Mo film (Comparative Example 1-1) and the laminated film of the W film 12 and the Mo film 13 (Example 1-4) are approximately the same, the laminated film has a smaller resistivity. The resistivity of the laminated film was approximately 17.3 μΩcm when the total film thickness was 10 nm, approximately 12.6 μΩcm when the total film thickness was 15 nm, and approximately 10 μΩcm when the total film thickness was 20 nm. The inventors aim to achieve a resistivity of 20 μΩcm or less for a laminated film with a total film thickness of, for example, 10 nm. In this regard, we believe that the laminated film of the W film 12 and the Mo film 13 obtained by the method of the present disclosure can be fully used as a wiring material for semiconductor devices.

[0038] Next, Fig. 9 shows the effect of changes in the thickness of the W film 12 on the resistivity of the laminated film. Fig. 9 shows the measurement results of the resistivity of the laminated film when the thickness of the W film 12 was set to 5 nm and 3 nm in the laminated film of Example 1-3. In the figure, the horizontal axis is the total thickness (nm) of the W film and Mo film (laminate film), and the vertical axis is the resistivity (μΩcm) of the laminated film. The values ​​for a W film thickness of 3 nm are plotted with open circles (○) and the values ​​for a W film thickness of 5 nm are plotted with filled circles (●).

[0039] As shown in this figure, we found that the resistivity of the laminated film was further reduced by increasing the thickness of the W film 12 from 5 nm to 3 nm. In other words, we confirmed that, when the total thickness of the W film 12 and Mo film 13 is approximately the same, the resistivity of the laminated film can be reduced by decreasing the thickness of the W film 12 and increasing the thickness of the Mo film 13. Since W has a higher resistivity than Mo, decreasing the film thickness further increases the resistivity due to the thin-wire effect. However, increasing the Mo film thickness accordingly decreases the resistivity of the laminated film as a whole. However, if the W film 12 is made too thin, the grain growth of the Mo film 13 may be impaired, raising concerns about the increased resistivity of the Mo film 13. Therefore, there is a preferred range for the thickness of the W film 12. For example, we believe that the thickness of the W film 12 should be set to 1 to 5 nm, with a value in the range of 2 to 3 nm being particularly preferable.

[0040] Next, we investigated the effect of the deposition temperature of the Mo film 13. As mentioned above, the Mo film 13 can be deposited by sputtering, ALD, CVD, or other methods. Sputtering is generally performed at room temperature, but ALD and CVD are often performed at high temperatures, for example, 350°C or higher. Since it is preferable to perform the wiring formation process at a temperature of 400°C or lower, we investigated the relationship between the deposition temperature and resistivity when depositing the Mo film 13 by ALD. Specifically, in the process of Examples 1-3, a Mo film 13 was formed on a W film 12 having a thickness of 3 nm and 5 nm, and a stacked film was formed by varying the film formation temperature and the thickness of the Mo film 13, and the resistivity of the stacked film was measured.

[0041] The results are shown in Figure 10. In the figure, the horizontal axis represents the total film thickness (nm) of the W film 12 and Mo film 13 (laminated film), and the vertical axis represents the resistivity (μΩcm) of the laminated film. In this figure, when the W film 12 is 3 nm thick, the deposition temperatures of the Mo film 13 are plotted as open squares (□), open triangles (△), and open circles (◯) for 350°C, 460°C, and 530°C, respectively. Furthermore, when the W film 12 is 5 nm thick, the deposition temperatures of the Mo film 13 are plotted as filled squares (■), filled triangles (▲), and 530°C, respectively.

[0042] From this figure, it was confirmed that, when the W film 12 had a thickness of 3 nm or 5 nm, the resistivity of the laminated film tended to decrease slightly as the deposition temperature of the Mo film 13 increased, but there was no significant change. Therefore, it was confirmed that a laminated film with low resistivity was formed even when the laminated film of the W film 12 and the Mo film 13 was deposited at a temperature of 400°C or less. Thus, the method of the present disclosure can be effectively applied to a low-temperature wiring formation process carried out at 400°C or less.

[0043] According to this embodiment, the W film 12 is used as a metal underlayer for the Mo film 13, and the Mo film 13 is formed on the W film 12. This increases the grain size of the Mo film 13, enabling the formation of a Mo film 13 with low resistivity. Furthermore, by laminating the W film 12 on the SiO2 film 11 formed on the wafer W, a W film with a high content of β-phase as the crystalline phase can be formed, further reducing the resistivity of the Mo film. As a result, in miniaturized semiconductor devices, using the Mo film 13 formed by the method of the present disclosure as a wiring material suppresses the increase in resistivity due to the thin wire effect, and improves problems such as wiring heat generation and wiring delay caused by increased resistivity.

[0044] Second Embodiment Next, a second embodiment of the present disclosure will be described with reference to FIGS. 11 to 15. In this embodiment, a titanium nitride film (TiN film) 14 is formed on an SiO film 11 having a recess formed on a wafer 10 (FIG. 11(a)), and then a W film 12 is formed on this TiN film 14 (FIG. 11(b)). Then, as shown in FIG. 11(c), a Mo film 13 is formed on the W film 12. Therefore, in this embodiment, the W film 12 is stacked on the TiN film 14.

[0045] The TiN film 14 functions as, for example, an adhesive layer, and its thickness is set to, for example, within a range of 2 nm to 3 nm. Such a TiN film 14 is formed by the ALD method or the CVD method using, for example, a gas containing titanium (Ti), such as titanium tetrachloride (TiCl4) gas, and a gas containing nitrogen (N), such as ammonia (NH3) gas. Also in this example, similarly to the first embodiment, the W film 12 and the Mo film 13 can be formed by the sputtering method, the ALD method, or the CVD method.

[0046] In this way, even when a TiN film 14 is formed on the wafer 10 and a laminated film of a W film 12 and a Mo film 13 is formed thereon, the resistivity of the Mo film 13 can be reduced compared to when only the Mo film 13 is formed on the wafer 10. The following description will be given with reference to data on the resistivity of the Mo film 13. 12 is a characteristic diagram showing the resistivity of the Mo film 13 for the W film 12 and Mo film 13 formed under ex-situ conditions. The thickness of the TiN film 14 was 3 nm, the thickness of the W film 12 was 5 nm, and the thickness of the Mo film 13 was varied within the range of 5 nm to 15 nm. The graph shows the results of measuring the resistivity by plotting the thickness (nm) of the Mo film 13 and the resistivity (μΩcm) of the Mo film 13. In FIG. 12, Example 2-1 is plotted using open inverted triangles (▽) and Comparative Example 2-1 is plotted using filled inverted triangles (▼).

[0047] In Example 2-1, a TiN film 14 was formed by the ALD method on a wafer 10 on which a SiO2 film 11 had been formed in advance and on which a recess had been formed, and then a W film 12 was formed by the sputtering method, and then a Mo film 13 was formed by the ALD method using a second Mo-containing gas as a source gas. The SiO2 film 11, W film 12, and Mo film 13 were formed in the same manner as in Examples 1 to 3. The TiN film 14 was formed using TiCl4 gas as the source gas and NH3 gas as the nitriding gas at a film formation temperature of 460°C and a pressure of 667 Pa.

[0048] In Comparative Example 2-1, a TiN film 14 was formed on a wafer 10 having an SiO2 film 11 formed thereon, and then a Mo film 13 was formed on the TiN film 14 by the ALD method using a second Mo source gas. The thickness of the TiN film 14 was 3 nm, and the film formation conditions for the SiO2 film 11, TiN film 14, and Mo film 13 were the same as those in Example 2-1.

[0049] 13 is a characteristic diagram showing the resistivity of the Mo film 13 for the W film 12 and Mo film 13 formed under in-situ conditions. The thickness of the TiN film 14 was 3 nm, the thickness of the W film 12 was 5 nm, and the thickness of the Mo film 13 was varied within a range of 5 nm to 15 nm. The horizontal axis in the diagram represents the thickness (nm) of the Mo film 13, and the vertical axis represents the resistivity (μΩcm) of the Mo film 13. In FIG. 13, Example 2-2 is plotted with open circles (◯), and Comparative Example 2-2 is plotted with filled circles (●).

[0050] In Example 2-2, a TiN film 14 was formed on a wafer 10 having an SiO2 film 11 formed thereon, and then a W film 12 was formed on the TiN film 14 by sputtering, and then a Mo film 13 was formed on the W film 12 by sputtering. The SiO2 film 11, W film 12, and Mo film 13 were formed in the same manner as in Example 1-4, and the TiN film 14 was formed in the same manner as in Example 2-1. In Comparative Example 2-2, a TiN film 14 was formed on a wafer 10 having an SiO2 film 11 formed thereon, and then a Mo film 13 was formed by sputtering on this TiN film 14. The thickness of the TiN film 14 was set to 3 nm, and the SiO2 film 11, TiN film 14, and Mo film 13 were formed in the same manner as in Example 2-2.

[0051] 12, it was confirmed that the resistivity of the Mo film 13 in Example 2-1 was lower than that in Comparative Example 2-1 when the film thickness of the Mo film 13 was approximately the same. Also, it was confirmed from FIG. 13 that the resistivity of the Mo film 13 in Example 2-2 was lower than that in Comparative Example 2-2 when the film thickness of the Mo film 13 was approximately the same. 12 and 13, it is apparent that even when a TiN film 14 is formed on the wafer 10 and a Mo film 13 is then formed thereon, the resistivity of the Mo film 13 is reduced by forming a W film 12 as an underlayer for the Mo film 13. However, it was found that the resistivity of the Mo film 13 can be further reduced by stacking the W film 12 on the SiO2 film 11, as in the first embodiment.

[0052] The reason for this is thought to be that in the first embodiment, the crystal structure of the W film underlying the Mo film 13 has a high content of β phase, whereas in the second embodiment, the crystal structure of the W film underlying the Mo film 13 mainly contains α phase. 14 shows the results of crystal structure analysis obtained by XRD for a W film 13 (5 nm thick) formed by sputtering on a wafer 10 on which a TiN film 14 (3 nm thick) had been formed. In the figure, the horizontal axis represents the diffraction angle 2θ (°) and the vertical axis represents the intensity (CPS). The diffraction angle of the α phase is shown by a dashed line, and the diffraction angle of the β phase is shown by a solid line.

[0053] As shown in this figure, the W film 13 formed on the TiN film 14 has many peaks corresponding to the diffraction angles of the α phase, and almost no peaks corresponding to the diffraction angles of the β phase, so it is recognized that the crystalline phase of the W film 13 is mainly the α phase. From the results of Figures 7 and 14, it was confirmed that when the W film 12 was formed on the SiO2 film 11, the crystalline phase of the W film 12 contained a large amount of β phase, and when the W film 12 was formed on the TiN film 14, the crystalline phase of the W film 12 was mainly α phase.

[0054] As described above, the W film 12 in this embodiment is mainly α-phase, and by using this W film 12 as an underlayer, the resistivity of the Mo film 13 is lower than that of the comparative example. Furthermore, by comparing Example 2-2 in FIG. 13 with Comparative Example 1-1 in FIG. 3 (an example in which the Mo film 13 is formed on the SiO2 film 11), it was found that when the thickness of the Mo film 13 was 5 nm, the resistivity of the Mo film 13 in Example 2-2 was lower. From these results, it is presumed that the grain size of the Mo film 13 is increased by laminating the W film 12 on the TiN film 14, resulting in a decrease in resistivity, although the effect is smaller than when the W film 12 is laminated on the SiO2 film 11.

[0055] In this embodiment, the resistivity of the laminated film in which the W film 12 and the Mo film 13 are laminated on the TiN film 14 was also measured, and the measurement results shown in Fig. 15 were obtained. In the figure, the horizontal axis represents the total thickness (nm) of the W film and the Mo film (laminate film), and the vertical axis represents the resistivity (µΩcm) of the laminated film, with Example 2-2 plotted as an open circle (○) and Comparative Example 2-2 plotted as a filled circle (●). As mentioned above, Example 2-2 is an example in which the W film 12 and the Mo film 13 were formed under in-situ conditions.

[0056] Thus, when Example 2-2 and Comparative Example 2-2 are compared, it is found that when the thickness of the Mo film 13 is 5 nm (the thickness of the laminated film in Example 2-2 is 10 nm), the laminated film of the W film 12 and the Mo film 13 has a lower resistivity than the Mo film 13. Therefore, it is understood that even when, for example, a TiN film 14 is formed on the wafer 10 as an adhesion layer, it can be sufficiently used as a wiring material for semiconductor devices. As described above, also in the second embodiment, the W film 12 is formed as a metal underlayer for the Mo film 13, and the Mo film 13 is formed on the W film 12. This increases the grain size of the Mo film 13, allowing the formation of a Mo film 13 with low resistivity.

[0057] Next, an apparatus for forming a Mo metal film on a wafer 10 (hereinafter referred to as a "film forming apparatus") will be described with reference to Figures 16 and 17, taking as an example the apparatus for forming a W film 12 and a Mo film 13 of the first embodiment. As shown in Figure 16, this film forming apparatus 2 performs step S1 of forming a W film 12 on a wafer 10 having a SiO2 film 11 formed thereon by sputtering (PVD: Physical Vapor Deposition), and step S2 of forming a Mo film 13 on the W film 12 by ALD.

[0058] 17, the film formation apparatus 2 is configured by arranging an atmospheric transfer chamber 21, a load lock chamber 22, a first vacuum transfer chamber 23, and a second vacuum transfer chamber 24. The atmospheric transfer chamber 21 is set to an atmospheric pressure atmosphere, and an atmospheric transfer mechanism 211 disposed therein is configured to transfer the wafers 10 between a carrier C that accommodates a plurality of wafers 10 and the load lock chamber 22. The carrier C is placed on a load port 201, and an SiO2 film 11 is previously formed on the wafers 10 accommodated therein, forming recesses. The load lock chamber 22 transfers the wafer 10 between the atmospheric transfer mechanism 211 and the first substrate transfer mechanism 231 arranged in the first vacuum transfer chamber 23, and its interior is configured to be adjustable between atmospheric pressure and the pressure inside the first vacuum transfer chamber 23.

[0059] The first vacuum transfer chamber 23 and the second vacuum transfer chamber 24 are each configured to have a rectangular shape in a plan view and are connected via, for example, two transfer units 27. The interiors of the first and second vacuum transfer chambers 23, 24 and the transfer unit 27 are set to a vacuum pressure atmosphere, and for example, the first vacuum transfer chamber 23 is configured to have a lower degree of vacuum than the second vacuum transfer chamber 24. The transfer unit 27 transfers the wafer 10 between the first substrate transfer mechanism 231 in the first vacuum transfer chamber 23 and the second substrate transfer mechanism 241 in the second vacuum transfer chamber 24. For this reason, the pressure of the transfer unit 27 is configured to be adjustable to the pressure of the first vacuum transfer chamber 23 and the pressure of the second vacuum transfer chamber 24.

[0060] For example, two Mo film formation modules 3 are connected to the left and right walls of the first vacuum transfer chamber 23. In this example, the Mo film formation modules 3 serve as second processing modules and are configured to form Mo films 13 by the ALD method. The first vacuum transfer mechanism 231 is configured to transfer wafers 210 between these four Mo film formation modules 3, the delivery unit 27, and the load lock chamber 22.

[0061] Furthermore, for example, two W film formation modules 4 are connected to the left and right walls of the second vacuum transfer chamber 24. In this example, the W film formation modules 4 serve as first processing modules and are configured to form W films 12 by sputtering. A second vacuum transfer mechanism 241 is configured to transfer wafers 10 between these four W film formation modules 4 and the transfer unit 27. In FIG. 17, symbols GV1 and GV2 indicate gate valves. Note that, between the first and second vacuum transfer chambers 23, 24 and the transfer section 27, between the load lock chamber 22 and the first vacuum transfer chamber 23, and between the load lock chamber 22 and the atmospheric transfer chamber 21, there are wafer transfer ports and gate valves for opening and closing the transfer ports, but these are not shown in the figure.

[0062] The film forming apparatus 2 having the above-described configuration includes a control unit 100. The control unit 100 is configured with a computer including a storage unit storing a program, a memory, and a CPU. The program is configured to output control signals from the control unit 100 to each part of the film forming apparatus 2 for performing control necessary to process the wafer 10. Such a program is stored in a storage unit of a computer, such as a flexible disk, a compact disk, a hard disk, a magneto-optical disk (MO), or a nonvolatile memory, and is read from the storage unit and installed in the control unit 100. The steps of transporting the wafer 10 in the film formation apparatus 2, forming the W film 12 in the W film formation module 4, and forming the Mo film 13 in the Mo film formation module 3 are executed based on control signals from the control unit 100.

[0063] Next, a configuration example of the W film formation module 4 constituting the first processing module will be described with reference to Fig. 18. This W film formation module 4 is configured as a sputtering device that forms a W film 12 on a wafer 10 by sputtering. As shown in Figure 18, the W film formation module 4 includes a processing container 41, a mounting table 42 provided in the processing container 41 on which a wafer 10 is placed, and a target 43 that emits metal (W) toward the wafer 10 placed on the mounting table 42.

[0064] For example, the processing vessel 41 is configured to include a main body 411, which is a generally cylindrical vessel with an open top, and a lid 412 that closes the opening of the main body 411. A gate valve GV that is connected to the second vacuum transfer chamber 24 is provided on a side wall surface of the main body 411. In addition, a vacuum exhaust unit (not shown) that evacuates the inside of the processing vessel 41 is connected to the main body 411.

[0065] In this example, the lid body 412 includes a horizontal ceiling portion 413 that is smaller than the main body 411 when viewed from above, and an inclined portion 414 that connects the ceiling portion 413 to the upper end of the side wall surface of the main body 411. A gas supply unit 49 is connected to the center of the ceiling portion 413 to supply a source gas of ions for sputtering (e.g., argon gas (Ar gas)) to the internal space of the processing vessel 41. Furthermore, the inclined portion 414 of the cover body portion 412 is provided with a holder 40 that holds a target 43 and a holder support portion 44 made of an insulator for fixing the holder 40 to the cover body portion 412. The holder 40 is connected to a power source 45.

[0066] The mounting table 42 includes a mounting table main body 421 and an electrostatic chuck 422 for fixing the wafer 10 to the mounting table 42. The mounting table 42 is connected to a drive unit 422 provided below the processing vessel 41 by a drive shaft 421 provided in the center of the underside of the mounting table 42. Thus, the mounting table 42 is rotatable about a vertical axis and is configured to move up and down between a transfer position and a processing position shown in FIG. 18. The transfer position is a position where the wafer 10 is transferred between the second substrate transfer mechanism 241 in the second vacuum transfer chamber 24 and the mounting table 42, and the processing position is set above the transfer position and is a position where a film formation process is performed on the wafer 10.

[0067] On the upper surface of the mounting table 42, there are arranged a shield plate 46 for preventing W, a metal emitted from the target 43, from depositing on the surface of the mounting table main body 421, and a mask 47 for forming a non-film-forming region (a region where a metal film is not formed) around the periphery of the wafer 10. The mask 47 is an annular member having a circular opening 471 with a diameter smaller than that of the wafer 10, which corresponds to the region where a W film, a metal film, is to be formed. In FIG. 18 , reference numeral 48 denotes a mask support, which is configured to remove the mask 47 from the mounting table 42 and support the removed mask 47 when transferring the wafer 10 between the mounting table 42 and the second substrate transfer mechanism 241.

[0068] In such a W film formation module 4, when the wafer 10 is placed on the mounting table 42 and placed at the processing position, and power is supplied from the power supply 45 to the holder 40, an electric field is generated near the target 43 held by the holder 40. This electric field dissociates the gas supplied from the gas supply unit 49 to generate ions, and these ions collide with the target 43, thereby releasing W atoms and other materials that serve as raw materials for the W film from the target 43. The W released from the target 43 is then deposited on the wafer 10 through the openings 471 in the mask 47, thereby forming a W film on the surface of the wafer 10.

[0069] Next, a configuration example of the Mo film formation module 3 constituting the second processing module will be described with reference to Fig. 19. This Mo film formation module 3 is configured as an apparatus for forming a Mo film 13 on a wafer 10 by the ALD method. As shown in this figure, the Mo film formation module 3 includes a processing vessel 31 having a substantially cylindrical shape for storing and processing wafers 10, and a mounting table 32 on which the wafers 10 are placed is disposed inside the processing vessel 31. The mounting table 32 is configured, for example, in a flat cylindrical shape and includes a built-in heater 321. A support part 322 extending downward is provided at the center of the underside of the mounting table 32.

[0070] In this example, the processing vessel 31 has a bottom wall with a central portion thereof protruding downward to form an exhaust chamber 33, and a lower end of a support portion 322 is connected to the bottom of the exhaust chamber 33. An exhaust mechanism 35 is connected to a side wall of the exhaust chamber 33 via an exhaust path 34. Furthermore, a transfer port 39 is formed in the side wall of the processing vessel 31, through which wafers 10 are loaded and unloaded from the processing vessel 31, and the transfer port 39 is configured to be freely opened and closed by a gate valve 391.

[0071] A shower head 36 is disposed in a region facing the mounting table 32 within the processing chamber 31. The shower head 36 is configured to discharge gas in a shower-like manner from a number of discharge ports 361 formed on the lower surface thereof toward the wafer 10 placed on the mounting table 32. A supply pipe 37 for supplying gas to the shower head 36 is connected to the processing vessel 31, and the base end of the supply pipe 37 branches to be connected to a metal-containing source gas supply source 381, a reducing gas supply source 382, ​​and a purge gas supply source 383. The branched supply pipe 37 is equipped with flow rate adjusters 371, 372, and 373 each equipped with a valve for opening and closing each flow path, a mass flow meter, etc. In this example, a first Mo-containing gas and a second Mo-containing gas are used as the source gas, hydrogen (H) gas is used as the reducing gas, and an inert gas such as nitrogen (N) gas or Ar gas is used as the purge gas.

[0072] In such a Mo film formation module 3, a wafer 10 on which a W film 12 has been formed is placed on a mounting table 32, the processing chamber 31 is evacuated to adjust the pressure to a predetermined value, and the wafer 10 on the mounting table 32 is heated to a predetermined temperature by a heater 321. Then, a cycle is performed in which the raw material gas and the reducing gas are sequentially supplied to the wafers 10 in the order of raw material gas → purge gas → reducing gas → purge gas into the processing vessel 31. By repeating this cycle a preset number of times, a Mo film 13 having a set thickness is formed.

[0073] 17 , the wafer 10 accommodated in the carrier C is transferred via the atmospheric transfer chamber 21, the load lock chamber 22, the first vacuum transfer chamber 23, the transfer unit 27, the second vacuum transfer chamber 24, and the W film formation module 4. Then, in the W film formation module 4, a W film 12 is formed on the wafer 10 by sputtering. Next, the wafer 10 is transferred via the second vacuum transfer chamber 24, the transfer unit 27, the first vacuum transfer chamber 23, and the Mo film formation module 3, where a Mo film 13 is formed on the W film 12 formed on the wafer 10 by ALD. Then, the wafer 10 is transferred via the first vacuum transfer chamber 23, the load lock chamber 22, the atmospheric transfer chamber 21, and the carrier C, before being stored back in the carrier C. In this example, the wafer 10 is transferred from the W film deposition module 4 to the Mo film deposition module 3 via the first and second vacuum transfer chambers 23 and 24, so that the W film 12 and the Mo film 13 are deposited in situ.

[0074] 17, the Mo film formation module 3 may be configured by a sputtering device using Mo as a target, and the Mo film 13 may be formed by a sputtering method. Also, the first vacuum transfer chamber 23 and the second vacuum transfer chamber 24 may be configured to have the same degree of vacuum.

[0075] Next, a configuration example of a film formation apparatus 5 for forming a W film 12 and a Mo film 13 according to the second embodiment will be described with reference to Fig. 20 and Fig. 21. As shown in Fig. 20, this apparatus performs step S11 of forming a TiN film 14 by ALD on a wafer 10 having a SiO2 film 11 formed thereon, step S12 of forming a W film 12 on the TiN film 14 by ALD, and step S13 of forming a Mo film 13 on the W film 12 by ALD.

[0076] 21 differs from the film formation apparatus 2 shown in FIG. 17 in the following configuration. In this film formation apparatus 5, a W film formation module 51 constituting a first processing module is connected to the first vacuum transfer chamber 23, and a TiN film formation module 52 that forms a TiN film 14 is also connected. Furthermore, a Mo film formation module 3 that forms a Mo film 13 by ALD is connected to the second vacuum transfer chamber 24 as a second processing module, and the first vacuum transfer chamber 23 and the second vacuum transfer chamber 24 are kept at the same vacuum level. The other configuration is the same as that of the film formation apparatus 2 shown in FIG. 17, and the same components are designated by the same reference numerals.

[0077] The W film formation module 51 and the TiN film formation module 52 are film formation modules that perform film formation by the ALD method. Therefore, the W film formation module 51 is configured to use, for example, tungsten pentachloride gas (WCl gas) as a raw material gas and, for example, H gas as a reducing gas in the film formation module 3 shown in FIG. The TiN film forming module 52 is configured in the film forming module 3 shown in FIG. 19 so that TiCl4 gas, for example, is used as the source gas and NH3 gas, for example, is used as the nitriding gas.

[0078] 21, the wafers 10 accommodated in the carrier C are transferred via the atmospheric transfer chamber 21, the load lock chamber 22, the first vacuum transfer chamber 23, and the TiN film formation module 52. Then, in the TiN film formation module 52, a TiN film 14 is formed on the wafers 10 by the ALD method. Next, the wafer 10 is transferred from the first vacuum transfer chamber 23 to the W film formation module 51, where the W film 12 is formed on the TiN film 14 by the ALD method.

[0079] Next, the wafer 10 is transferred via the route of the first vacuum transfer chamber 23 → the transfer unit 27 → the second vacuum transfer chamber 24 → the Mo film formation module 3, where a Mo film 13 is formed on the W film 12. Thereafter, the wafer 10 is transferred via the route of the second vacuum transfer chamber 24 → the transfer unit 27 → the first vacuum transfer chamber 23 → the load lock chamber 22 → the atmospheric transfer chamber 21 → the carrier C, and is stored back in the carrier C. In this example, the wafer 10 is also transferred from the W film forming module 51 to the Mo film forming module 3 via the first and second vacuum transfer chambers 23 and 24, so that the W film 12 and the Mo film 13 are formed in situ.

[0080] However, the film formation apparatus 5 shown in Fig. 21 does not necessarily have to include the TiN film formation module 52. Also, the W film formation module 51 and the Mo film formation module 3 may be configured using the sputtering apparatus shown in Fig. 18, and the W film 12 and the Mo film 13 may be formed by sputtering, respectively.

[0081] In the above, the apparatuses for forming the W film 12 and the Mo film 13 of the first and second embodiments do not necessarily have to be configured as in the film formation apparatuses 2 and 5 of Figures 17 and 21, in which the first and second process modules are connected to a vacuum transfer chamber. For example, the sputtering apparatus shown in Figure 18 may be used alone, with one target being W and the other being Mo, so that the first process module for forming the W film and the second process module for forming the Mo film are shared. Even in this case, the W film 12 and the Mo film 13 can be formed under in-situ conditions.

[0082] Furthermore, when the W film 12 and the Mo film 13 are formed by the ALD method, the source gas, reducing gas, and purge gas are not limited to the above examples. Furthermore, the layout of the film formation apparatuses 2 and 5 described above is an example, and the film formation apparatuses 2 and 5, the sputtering apparatus shown in Fig. 18, and the film formation module shown in Fig. 19 are not limited to the above configurations.

[0083] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive, and the above-described embodiments may be omitted, substituted, or modified in various ways without departing from the scope and spirit of the appended claims. [Explanation of symbols]

[0084] 10 wafers 12 W film (tungsten metal undercoat film) 13 Mo film (molybdenum metal film)

Claims

1. 1. A method for depositing a molybdenum metal film on a substrate, comprising: forming a tungsten metal underlayer on the substrate; forming the metal film on the metal underlayer.

2. The method according to claim 1 , wherein the metal underlayer is laminated on a silicon oxide film or a titanium nitride film formed on the substrate.

3. The method of claim 1 , wherein the metal underlayer is deposited by sputtering.

4. The method of claim 1 , wherein the metal film is deposited by ALD or sputtering.

5. When the metal film is formed by the ALD method, MoO ２ Cl ２ The method according to claim 4, wherein a feed gas containing:

6. 5. The method according to claim 4, wherein a source gas containing a molybdenum halide that does not contain oxygen is used when the metal film is formed by the ALD method.

7. 2. The method according to claim 1, wherein the thickness of the metal underlayer is within a range of 1 to 5 nm.

8. An apparatus for depositing a molybdenum metal film on a substrate, comprising: a first processing module for depositing a tungsten metal film on the substrate; a second processing module for depositing a metal film of molybdenum on the substrate; a control unit, the controller is configured to output control signals to perform a step of forming a tungsten metal liner on the substrate in the first processing module and a step of depositing the molybdenum metal film on the metal liner in the second processing module.

9. a vacuum transfer chamber to which the first processing module and the second processing module are connected, and a substrate transfer mechanism disposed in the vacuum transfer chamber; 9. The apparatus according to claim 8, wherein the control unit is configured to output a control signal for performing a step of transferring the substrate from the first processing module to the second processing module via the vacuum transfer chamber between the step of forming the metal underlayer and the step of depositing the molybdenum metal film.

10. 10. The apparatus of claim 9, wherein the first processing module is configured to deposit the tungsten metal liner film by a sputtering process and the second processing module is configured to deposit the molybdenum metal film by an ALD process.

11. 10. The apparatus of claim 9, wherein the first process module is configured to deposit the tungsten metal underlayer by an ALD process and the second process module is configured to deposit the molybdenum metal film by an ALD process.

12. 10. The apparatus according to claim 9, wherein the first processing module is configured to deposit the tungsten metal underlayer by a sputtering method, the second processing module is configured to deposit the molybdenum metal film by a sputtering method, and the first processing module and the second processing module are common.

Images