Method for controlling resistivity and stress of tungsten by using PVD (Physical Vapor Deposition) sputtering method

Abstract

The present invention relates to a method for forming a tungsten film on a semiconductor device, which is a method for forming a tungsten (W) film on a semiconductor substrate by means of a physical vapor deposition sputtering method, and is characterized by comprising: a) a first deposition step for depositing a tungsten film on the semiconductor substrate by means of magnetron sputtering having a power density of less than 0.5 W / cm2; b) a step of performing an RF bias treatment in an inert gas atmosphere, thereby modifying the deposited tungsten surface; and c) a second deposition step for further depositing a tungsten film on the deposited tungsten film by magnetron sputtering having a power density of 0.5 W / cm2 or more.

Description

Technical Field

[0001] The present invention relates to a method for controlling the resistivity and stress of a semiconductor substrate film by using a physical vapor deposition (PVD) sputtering method, and more specifically, to a tungsten (W) film forming method for a semiconductor device by using a PVD sputtering method and a tungsten film manufactured by the method. Background Art

[0002] Recently, as the size of various devices has become smaller, the demand for ultra thin films in semiconductor devices has increased. Therefore, metals with low resistivity such as Cu that have been used in the past have a problem that the resistivity increases sharply as the thickness becomes thinner due to the characteristics of the material. Therefore, due to the miniaturization of semiconductor devices, etc., research is being conducted on using relatively low resistivity materials such as tungsten (W), Ru (ruthenium), molybdenum (Mo), and rhodium (Rh) for the next-generation wiring structure.

[0003] Therefore, the inventors have confirmed that when tungsten (W) is used to replace previous materials such as Cu and the PVD sputtering method is used to deposit the thin film, after repeatedly performing deposition and plasma treatment during the deposition of the seed layer to improve the initial interface layer, a tungsten thin film is grown on the improved interface layer, thereby controlling the particle size and particle orientation of the deposited tungsten thin film, thereby ultimately obtaining a tungsten thin film with significantly improved resistivity, and the stress of the film is also controlled. Summary of the invention

[0004] [Problems to be solved by the invention]

[0005] In the conventional PVD process, a common method of depositing tungsten or the like forms a metal film through a single process step at a constant DC power. However, unlike the conventional process that forms a film through a single process step, the present invention aims to improve the particle size and resistivity of the deposited tungsten by depositing tungsten at a low power, applying only an RF stage bias to perform plasma treatment, and repeating the process 1 to 4 times.

[0006] Another object of the present invention is to control the initial interface of tungsten by repeating the above process, while forming stress in the tensile direction, thereby obtaining a film quality with stress close to zero in a compressive film quality.

[0007] However, the problems to be solved by the present invention are not limited to the problems mentioned above, and those skilled in the art can clearly understand other problems not mentioned based on the following description.

[0008] [Methods of solving the problem]

[0009] According to one embodiment of the present invention, a method for forming a tungsten film of a semiconductor device is provided, which is a method for forming a tungsten (W) film of a semiconductor device implemented by a physical vapor deposition (PVD) sputtering method on a semiconductor substrate, and is characterized by comprising:

[0010] a) a first deposition step of depositing a tungsten film on the semiconductor substrate by magnetron sputtering with a power density of less than 0.5 W / cm2;

[0011] b) performing RF bias treatment in an inert gas environment to modify the surface of the deposited tungsten; and

[0012] c) a second deposition step of further depositing a tungsten film on the deposited tungsten film by magnetron sputtering with a power density of 0.5 W / cm 2 or more.

[0013] According to another embodiment of the present invention, there is provided a tungsten film of a semiconductor device, which is a tungsten film of a semiconductor device manufactured by a tungsten film forming method including the following steps a) to c), and has a tungsten film quality in which the ratio of particles with a particle size of 0.12 μm or more is 50% or more, the method comprising:

[0014] a) a first deposition step of depositing a tungsten film on the semiconductor substrate by magnetron sputtering with a power density of less than 0.5 W / cm2;

[0015] b) performing RF bias treatment in an inert gas environment to modify the surface of the deposited tungsten; and

[0016] c) a second deposition step of further depositing a tungsten film on the deposited tungsten film by magnetron sputtering with a power density of 0.5 W / cm 2 or more.

[0017] [Effects of the Invention]

[0018] The advantage of the tungsten film forming method of one embodiment of the present invention is that it can replace the materials such as Cu used in the past, and divide the PVD method into a first deposition step, a surface modification step and a second deposition step for deposition, thereby controlling the particle size and particle orientation of the deposited tungsten film.

[0019] In addition, compared with the previous PVD process, low resistivity can be obtained by increasing the particle size of the tungsten film and increasing the ratio of particles with (110) orientation. When the film forming method of an embodiment of the present invention is applied, tensile deformation occurs inside and the crystal plane distance of each grain becomes different, so the stress of tungsten can also be controlled.

[0020] Furthermore, it has the following effect: in the tungsten film forming process, the resistivity reduction effect can be optimally adjusted by implementing the first deposition step and the surface modification step 1 to 4 times before the second deposition step, or adjusting the tungsten film forming conditions (DC voltage, Ar, Kr flow, etc.), so that the tungsten film obtained thereby exhibits excellent quality.

[0021] The effects of the present invention are not limited to the above-mentioned effects, and should be understood to include all effects that can be inferred from the configuration of the invention described in the detailed description of the present invention or the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A diagram showing a tungsten film forming process according to an embodiment of the present invention.

[0023] Figure 2 This is a diagram schematically comparing a conventional tungsten film forming process with a tungsten film forming process according to an embodiment of the present invention.

[0024] Figure 3 This is a graph showing the magnitude of resistivity corresponding to the number of repetitions of the first deposition step in a tungsten film forming process according to an embodiment of the present invention.

[0025] Figure 4 The figure compares a conventional process having only the second deposition step and a process having only the first and second deposition steps without performing RF bias treatment, with a tungsten film forming process (performing the first deposition step four times) according to an embodiment of the present invention.

[0026] Figure 5 It is a graph showing the magnitude of resistivity corresponding to the DC power in the first deposition step and the second deposition step.

[0027] Figure 6 This is a graph showing the ratio of each tungsten grain size obtained by the tungsten film forming process according to one embodiment of the present invention.

[0028] Figure 7 This is a diagram showing the results of XRD (X-ray diffraction) measurement of a tungsten film manufactured by a tungsten film forming process according to an embodiment of the present invention.

[0029] Figure 8 The figure compares the EBSD (Electron Back Scatter Diffraction) measurement results of a tungsten film manufactured by the tungsten film forming process according to one embodiment of the present invention and a tungsten film manufactured by a conventional process. DETAILED DESCRIPTION

[0030] Hereinafter, the embodiments are described in detail with reference to the accompanying drawings. However, various changes can be made to the embodiments, so the scope of the patent application is not limited or restricted to these embodiments. It should be understood that all changes, equivalents and substitutes of the embodiments are included in the scope of rights.

[0031] The terms used in the embodiments are for illustrative purposes only and should not be interpreted as limiting the intent. Unless otherwise clearly stated in the context, singular expressions include plural expressions. It should be understood that in this specification, terms such as "including" or "having" are used to specify the presence of features, numbers, steps, actions, constituent elements, parts or combinations thereof recorded in the specification, and do not preclude the presence or additional possibility of one or more other features, numbers, steps, actions, constituent elements, parts or combinations thereof.

[0032] Including technical or scientific terms, unless otherwise defined, all terms used herein have the same meaning as commonly understood by a person of ordinary skill in the technical field to which the embodiments belong. Commonly used pre-defined terms should be interpreted as having the same meaning as that in the context of the relevant technology, and should not be interpreted as idealized or overly formalized unless otherwise clearly defined in this application.

[0033] In addition, when describing the drawings with reference to the drawings, the same components are given the same reference numerals regardless of the reference numerals, and repeated descriptions are omitted. When describing the embodiments, if it is determined that the detailed description of the related known technology will unnecessarily confuse the main purpose of the embodiments, the detailed description will be omitted.

[0034] According to one embodiment of the present invention, a tungsten film forming method for a semiconductor device is provided, which is a tungsten (W) film forming method for a semiconductor device implemented by a physical vapor deposition (PVD) sputtering method on a semiconductor substrate, and is characterized by comprising:

[0035] a) a first deposition step of depositing a tungsten film on the semiconductor substrate by magnetron sputtering with a power density of less than 0.5 W / cm2;

[0036] b) performing RF bias treatment in an inert gas environment to modify the surface of the deposited tungsten; and

[0037] c) a second deposition step of further depositing a tungsten film on the deposited tungsten film by magnetron sputtering with a power density of 0.5 W / cm 2 or more.

[0038] In the step a) (first deposition step), DC power and RF power (RF level bias) can be used to deposit a tungsten film at a low power density (less than 0.5 W / cm2), so that the thickness of the tungsten film formed on the semiconductor substrate can be 0.3 to 0.6 nm.

[0039] When the thickness of the tungsten film formed by the first deposition step is less than 0.3 nm or exceeds 0.6 nm, as shown in Table 3 of Examples described below, there arises a problem that the resistivity of the formed tungsten film increases.

[0040] In the first deposition step, the DC power is preferably as low as possible, and specifically, may be less than 1 kW, and as an example, may be 0.2 kW to 0.6 kW, and more specifically, may be 0.4 kW. In addition, the RF power applied simultaneously with the DC power may be used in the range of 50 W to 200 W.

[0041] On the other hand, the type of the semiconductor substrate used in the tungsten film formation is not generally limited as long as it is a wafer substrate that can exhibit the same process effect, and as one example, a SiO2 wafer can be used.

[0042] Furthermore, after the first deposition step of tungsten in step a), the method may include the step b) of modifying the surface of the tungsten to be deposited.

[0043] The step b) includes the following process: only RF power is applied without applying DC power, and the plasma of the gas is formed by using one or more inert gases selected from the group consisting of Ar, Kr, Ne and Xe. At this time, considering the effect of the invention, it is better to use Kr gas than Ar gas, but the type thereof is generally not limited.

[0044] Furthermore, the RF power may be 50 W to 200 W, and the RF bias treatment is performed for about 2 seconds to 10 seconds, thereby having the advantage of being able to improve the interface of the tungsten film.

[0045] On the other hand, in the tungsten film forming method for a semiconductor device according to an embodiment of the present invention, the steps a) and b) can be performed not only once but also up to 4 times. Thus, the first deposited tungsten film can be deposited to a thickness of 0.3 nm to 2.4 nm.

[0046] As described above, by performing the first deposition step (step a)) and the surface modification step (step b)) for more than one time and less than four times, the interface of the seed layer can be improved, the particle size of the manufactured tungsten film can be increased, and the resistivity can be improved.

[0047] In the case where the steps a) and b) are not performed (0 times), or the steps a) and b) are repeated more than 4 times, Figure 3 As shown in the figure, the resistivity of the tungsten film increases and is not suitable for use as a semiconductor device in a small device. In particular, it can be seen that when the number of repetitions of step a) and step b) is 5 times, 8 times, and 12 times, the resistivity is so large that it is not much different from the case where only the second deposition process is performed (step a) and step b) are not performed) ( Figure 3 ).

[0048] Furthermore, by repeatedly performing the first deposition step and the surface modification step, stress can be formed in the tensile direction while controlling the initial interface of tungsten, and a film quality with stress close to zero can be obtained in a compressive film quality.

[0049] On the other hand, a tungsten film forming method for a semiconductor device according to an embodiment of the present invention may include the following second deposition step (step c): after repeatedly implementing step a) and step b) 1 to 4 times, a tungsten film is further deposited on the deposited tungsten film using high power density (above 0.5 W / cm2) magnetron sputtering.

[0050] Thus, a tungsten film can be deposited to a desired thickness at one time. At this time, the thickness of the deposited tungsten film is not particularly limited.

[0051] On the other hand, considering the resistivity of the formed tungsten film, the DC power applied in the first deposition step of step a) is preferably less than or equal to the DC power applied in the second deposition step of step c).

[0052] According to the following Figure 5 It can be seen that, for the process in which the DC power applied in the first deposition step is greater than the DC power applied in the second deposition step, the measured resistivity is similar to that of the conventional process in which only the second deposition step is performed, showing a slightly larger resistivity. The DC power applied in the second deposition step may be specifically 1.0 kW or more, and as an example, may be 1.0 kW or more and less than 3.0 kW, or 1.0 kW to 1.6 kW, or more specifically 1.2 kW.

[0053] Preferably, the steps a), b) and c) are all carried out in a chamber capable of performing physical vapor deposition sputtering, and the pressure condition of the chamber is below 1 Pa.

[0054] According to another embodiment of the present invention, there is provided a tungsten film of a semiconductor device, which is a tungsten film of a semiconductor device manufactured by a tungsten film forming method including the following steps a) to c), and has a tungsten film quality in which the ratio of particles with a particle size of 0.12 μm or more is 50% or more, the method comprising:

[0055] a) a first deposition step of depositing a tungsten film on the semiconductor substrate by magnetron sputtering with a power density of less than 0.5 W / cm2;

[0056] b) performing RF bias treatment in an inert gas environment to modify the surface of the deposited tungsten; and

[0057] c) a second deposition step of further depositing a tungsten film on the deposited tungsten film by magnetron sputtering with a power density of 0.5 W / cm 2 or more.

[0058] The process for manufacturing a tungsten film for a semiconductor device is substantially the same as the process described in detail above. Unlike the conventional process in which only the second deposition step is performed, the ratio of particles having a particle size of 0.12 μm or more in the manufactured tungsten film can be more than 50%. In contrast, in the conventional process in which only the second deposition step is performed, the ratio of particles having a particle size of 0.12 μm or more is only about 9%, showing a significant difference in tungsten film quality ( Figure 6 ).

[0059] And, if Figure 7 As shown in the figure, compared with the conventional process, the tungsten film manufactured according to an embodiment of the present invention achieves a (110) peak shift, which means that the crystal plane distance of the crystal grains in the film changes, thereby generating tensile stress in the film. In addition, it can be seen that compared with the conventional process, the number of crystal grains indicating the (110) orientation increases, and a tungsten film with a ratio of more than 50% can be obtained, which results in an effect of improving the resistivity ( Figure 8 ).

[0060] The present invention will be described in more detail below by way of examples. The following examples are provided for the purpose of illustrating the present invention, but the scope of the present invention is not limited thereto.

[0061] <Example>

[0062] 1. Tungsten film formation method for semiconductor devices

[0063] -Example 1

[0064] 1) The first deposition process of tungsten (W)

[0065] The film formation was performed using ULVAC ENTRON #1 experimental equipment based on a physical vapor deposition (PVD) sputtering system.

[0066] A 0.4 kW DC power and an RF bias are simultaneously applied to a SiO2 semiconductor substrate to form a 0.5 nm thick tungsten film at a low power density (Low Power Density; less than 0.5 W / cm2).

[0067] 2) RF bias treatment process

[0068] An inert gas is supplied into the chamber, and only RF power of 50 W to 200 W is applied to the stage for 5 seconds without applying DC power to form an inert gas plasma, and then an RF bias treatment is performed on the manufactured tungsten film.

[0069] 3) Second deposition process of tungsten (W)

[0070] The 1.2 kW DC power and RF bias are applied to the tungsten film treated with RF bias, and a tungsten film with a thickness of about 38 nm is further formed at a high power density (Low Power Density; above 0.5 W / cm2), and finally a tungsten film with a thickness of 38.52 nm is produced.

[0071] -Examples 2 to 3 (variation in the number of times the first deposition is performed)

[0072] The first tungsten deposition process and RF bias treatment process were implemented twice (Example 2) and four times (Example 3). Otherwise, the tungsten film was manufactured in the same manner as in Example 1. As a result, tungsten films with thicknesses of 38.13 nm and 37.74 nm were obtained, respectively.

[0073] -Comparative Example 1 (Normal Deposition)

[0074] On the SiO-2 substrate, the first deposition process and RF bias treatment process of tungsten (W) in Example 1 were not performed, but only the second deposition process was performed using a DC power of 1.2 kW, resulting in a tungsten film with a total thickness of 38.8 nm.

[0075] -Comparative Example 2

[0076] On the SiO-2 substrate, the RF bias treatment process of the first embodiment is not performed, but only the first deposition process and the second deposition process of tungsten (W) are performed, and as a result, a tungsten film with a total thickness of 37.3 nm is obtained.

[0077] - Comparative Examples 3 to 5 (variation in the number of times the first deposition was performed)

[0078] The first tungsten deposition process and RF bias treatment process were implemented 5 times (Comparison Example 3), 8 times (Comparison Example 4), and 12 times (Comparison Example 5). Otherwise, the tungsten film was manufactured in the same manner as in Example 1. As a result, tungsten films with thicknesses of 38.2nm, 38.39nm, and 37.70nm were obtained, respectively.

[0079] The resistivity of each tungsten film manufactured by Examples 1 to 3 and Comparative Examples 1 to 5 was measured and shown in the following Tables 1 and Figure 3 :

[0080] [Table 1]

[0081]

[0082] 2. Resistivity measurement results at various DC powers

[0083] - Example 4 (DC power of the first deposition step <DC power of the second deposition step)

[0084] The process time in the second deposition step of tungsten (W) is changed to obtain a tungsten film with a final thickness of 50.16 nm. In addition, the first deposition step, the RF bias treatment step, and the second deposition step are implemented in the same manner as in Example 3. As a result, a tungsten film with a resistivity of 8.47 μΩcm is manufactured.

[0085] - Example 5 (DC power of the first deposition step = DC power of the second deposition step)

[0086] A tungsten film was manufactured in the same manner as in Example 4 except that a DC power of 1.2 kW was used in the first deposition step of tungsten (W). As a result, a tungsten film having a thickness of 51.24 nm and a resistivity of 9.71 μΩcm was obtained.

[0087] - Comparative Example 6 (DC power of the first deposition step > DC power of the second deposition step)

[0088] A tungsten film was manufactured in the same manner as in Example 4 except that a DC power of 1.6 kW was used in the first deposition step of tungsten (W). As a result, a tungsten film having a thickness of 53.96 nm and a resistivity of 10.02 μΩcm was obtained.

[0089] -Comparative Example 7 (Normal Deposition)

[0090] In order to compare with Examples 4, 5 and Comparative Example 6, the first deposition process and RF bias treatment process of tungsten (W) are not implemented on the SiO-2 substrate. Instead, only the second deposition process is implemented using a DC power of 1.2 kW to obtain a tungsten film with a total thickness of 50.14 nm. The resistivity of the tungsten film is measured to be 10.18 μΩcm.

[0091] The power level and resistivity of each tungsten film manufactured by the above-mentioned Examples 4 to 5 and Comparative Examples 6 to 7 are compared and shown in the following Tables 2 and Figure 5 :

[0092] [Table 2]

[0093]

[0094]

[0095] 3. Analysis of resistivity change of film thickness per deposition step

[0096] The film thickness of each deposition in the first deposition step is set to 0.1nm, 0.3nm, 0.4nm, 0.5nm, 0.6nm, 0.9nm and 1.0nm respectively, so that the first deposition step is repeatedly performed 4 times in the same way as in the third embodiment, and after performing RF bias treatment, the second deposition step is performed to form a tungsten film.

[0097] The resistivity of these film thicknesses was determined and is summarized in Table 3 below:

[0098] [Table 3]

[0099]

[0100] This shows that when the thickness of the tungsten film formed in the first deposition step is less than 0.3 nm or exceeds 0.6 nm, the resistivity of the formed tungsten film increases.

[0101] 4. Particle size and orientation analysis

[0102] -Analysis of particle size and the proportion of each size ( Figure 6 )

[0103] The tungsten film formed by the conventional process (Comparative Example 1) and the improved process of one embodiment of the present invention (Example 3) was measured and analyzed by EBSD (Electron backscatter diffraction), which is one of the methods for analyzing the grain orientation in the sample by analyzing the diffraction pattern of backscattered electrons using an ultra-high resolution field emission scanning electron microscope (FESEM) JSM-IT800 device. The surface particle size is calculated by the EBSD to express the ratio of each particle size ( Figure 6 ).

[0104] The results show that in the tungsten film manufactured according to Comparative Example 1 (conventional process), the ratio of particles with a particle size of 0.12 μm or more is only about 9%. On the contrary, in the tungsten film manufactured according to Example 3 (improved process), the ratio of particles with a particle size of 0.12 μm or more is 51.9%.

[0105] -XRD (X-ray diffraction) measurement and analysis ( Figure 7 & Table 4)

[0106] In order to analyze the characteristics of the crystalline material, an XRD Rigaku SmartLab (9kW) device was used to perform XRD (X-ray diffraction) analysis on the tungsten films formed according to the conventional process (Comparative Example 1) and the improved process of one embodiment of the present invention (Examples 2 and 3). Figure 7 ).

[0107] As a result, it was found that the positions of the W(110) peaks of the tungsten films manufactured according to Examples 2 and 3 were shifted compared to the tungsten films manufactured according to Comparative Example 1, which indicates that the stress was changed.

[0108] [Table 4]

[0109]

[0110] - Calculation of grain orientation and ratio of tungsten film ( Figure 8 )

[0111] With the Figure 6 Similarly, EBSD measurement and analysis were performed on the tungsten film formed by the conventional process (Comparative Example 1) and the improved process of one embodiment of the present invention (Example 3). The orientation and orientation ratio of the grains were calculated by the EBSD, and the increase in the grain size ( Figure 8 ).

[0112] As a result, in the tungsten film manufactured according to Comparative Example 1 (existing process), the ratio of particles with (110) orientation was 46.24%. On the contrary, in the tungsten film formed according to Example 3, the ratio of particles with (110) orientation was 54.30%. It can be seen that compared with the previous process, the (110) orientation of the improved process increased by about 8%, and it can be seen that the particle size is also larger in the improved process (Example 3).

[0113] As described above, the embodiments are described according to the limited drawings, but a person skilled in the art can apply various technical modifications and variations based on the above description. For example, even if the described techniques are implemented in a different order from the described method, and / or the described constituent elements are combined or combined in a different form from the described method, or replaced or substituted with other constituent elements or equivalents, appropriate results can be achieved.

[0114] Accordingly, other implementations, other embodiments, and equivalents of the claims are within the scope of the appended claims.

Claims

1. A method for forming a tungsten film for a semiconductor device, which is a method for forming a tungsten (W) film for a semiconductor device by physical vapor deposition sputtering on a semiconductor substrate, characterized in that include: a) a first deposition step of depositing a tungsten film on the semiconductor substrate by magnetron sputtering with a power density of less than 0.5 W / cm2; b) performing RF bias treatment in an inert gas environment to modify the surface of the deposited tungsten; and c) a second deposition step of further depositing a tungsten film on the deposited tungsten film by magnetron sputtering with a power density of 0.5 W / cm 2 or more.

2. The tungsten film forming method for a semiconductor device according to claim 1, characterized in that: The thickness of the tungsten film deposited in step a) is 0.3 to 0.6 nm.

3. The tungsten film forming method for a semiconductor device according to claim 1, wherein: Before step c), step a) and step b) are performed 1 to 4 times.

4. The tungsten film forming method for a semiconductor device according to claim 3, wherein: The thickness of the tungsten film deposited through step a) and step b) is 0.3 to 2.4 nm.

5. The tungsten film forming method for a semiconductor device according to claim 1, wherein: The DC power applied in the step a) is less than or equal to the DC power applied in the step c).

6. The tungsten film forming method for a semiconductor device according to claim 1, wherein: The DC power applied in step a) is less than 1.0 kW, and the DC power applied in step c) is greater than 1.0 kW and less than 3.0 kW.

7. The tungsten film forming method for a semiconductor device according to claim 1, wherein: The inert gas in step b) includes at least one selected from the group consisting of Ar, Kr, Ne and Xe.

8. The tungsten film forming method for a semiconductor device according to claim 1, characterized in that: The RF bias treatment in step b) is performed at 50 W to 200 W for 2 seconds to 10 seconds.

9. The tungsten film forming method for a semiconductor device according to claim 1, wherein: In the step b), the plasma treatment is performed by applying only RF bias without applying DC power. 10 . The method for forming a tungsten film for a semiconductor device according to claim 1 , which is performed in a physical vapor deposition chamber at a pressure of 1 Pa or less.

11. A tungsten film for a semiconductor device, which is a tungsten film for a semiconductor device manufactured by a tungsten film forming method comprising the following steps a) to c), and has a tungsten film quality in which the ratio of particles with a particle size of 0.12 μm or more is 50% or more, the method comprising: a) a first deposition step of depositing a tungsten film on the semiconductor substrate by magnetron sputtering with a power density of less than 0.5 W / cm2; b) performing RF bias treatment in an inert gas environment to modify the surface of the deposited tungsten; and c) a second deposition step of further depositing a tungsten film on the deposited tungsten film by magnetron sputtering with a power density of 0.5 W / cm 2 or more.

12. The tungsten film of a semiconductor device according to claim 11, wherein The ratio of crystal grains having a (110) orientation is 50% or more.

Images