Method for controlling the resistivity and stress of tungsten through PVD sputtering.

Abstract

A method for controlling the resistivity and stress of tungsten through a PVD sputtering method capable of controlling the initial interface of tungsten, forming stress in the tensile direction, and obtaining a film having a film quality close to 0 with a compressed film quality. 【Solution means】The present invention is a method for forming a tungsten film of a semiconductor element using a physical vapor deposition sputtering method on a semiconductor substrate, comprising: a) a first deposition step of depositing a tungsten film using magnetron sputtering with a power density of less than 0.5 W / cm 2 on the semiconductor substrate; b) a step of performing an RF biasing treatment in an atmosphere of an inert gas to modify the surface of the deposited tungsten; and c) a second deposition step of additionally depositing a tungsten film on the deposited tungsten film using magnetron sputtering with a power density of 0.5 W / cm 2 or more. The present invention relates to a method for forming a tungsten film of a semiconductor element, characterized by including the above steps.

Description

[Technical Field]

[0001] This invention relates to a method for controlling the resistivity and stress of a semiconductor substrate film using a physical vapor deposition (PVD) sputtering method, and more specifically, to a method for depositing a tungsten (W) film on a semiconductor device using a PVD sputtering method, and to a tungsten film manufactured thereby. [Background technology]

[0002] In recent years, the decreasing size of various devices has led to an increased need for ultra-thin films in semiconductor devices and other applications. However, metals with low resistivity, such as copper (Cu), which are already in use, have a problem in that their resistivity increases sharply as their thickness decreases due to their material properties. Therefore, in next-generation wiring structures resulting from the miniaturization of semiconductor devices and other applications, materials with relatively low resistivity, such as tungsten (W), ruthenium (Ru), molybdenum (Mo), and rhodium (Rh), are being considered.

[0003] Here, the inventors have found that by utilizing tungsten (W) to replace existing materials such as Cu, and by repeatedly performing deposition and plasma treatment during thin film deposition using the PVD sputtering method to improve the initial interface layer of the seed layer, and then growing a tungsten thin film on the improved interface layer, the particle size and orientation of the deposited tungsten thin film can be controlled. As a result, it is possible to obtain a tungsten thin film with significantly improved resistivity, and it has been confirmed that the stress of the thin film can also be controlled. [Overview of the project] [Problems that the invention aims to solve]

[0004] Conventional PVD processes for depositing tungsten and other materials involve depositing a metal film in a single step using a constant DC power. However, unlike existing processes consisting of a single step, the present invention aims to improve the particle size and resistivity of the deposited tungsten by applying only an RF stage bias after tungsten deposition at low power, performing plasma treatment, and repeating this process 1 to 4 times.

[0005] Furthermore, the objective is to control the initial interface of tungsten through the aforementioned iterative process, thereby creating stress in the tensile direction and obtaining a film with a stress close to zero in the compressed film.

[0006] However, the problems that this invention aims to solve are not limited to those mentioned above, and further problems not mentioned can be clearly understood by those with ordinary skill in the art from the following description. [Means for solving the problem]

[0007] According to one embodiment of the present invention, a method for depositing a tungsten (W) film on a semiconductor substrate using a physical vapor deposition (PVD) sputtering method,

[0008] a) 0.5 W / cm² on the semiconductor substrate 2 A first deposition step involves depositing a tungsten film using magnetron sputtering with a power density of less than 100%,

[0009] b) A step of modifying the surface of the deposited tungsten by performing RF biasing treatment in an inert gas atmosphere,

[0010] c) Apply 0.5 W / cm² to the deposited tungsten film. 2 A second deposition step involves additionally depositing a tungsten film using magnetron sputtering with the above power density,

[0011] A method for depositing a tungsten film on a semiconductor device is provided, characterized by including [the following].

[0012] According to another embodiment of the present invention, a tungsten film of a semiconductor device manufactured by a tungsten film deposition method comprising the following steps a) to c),

[0013] a) 0.5 W / cm² on the semiconductor substrate 2 A first deposition step involves depositing a tungsten film using magnetron sputtering with a power density of less than 100%,

[0014] b) A step of modifying the surface of the deposited tungsten by performing RF biasing treatment in an inert gas atmosphere,

[0015] c) Apply 0.5 W / cm² to the deposited tungsten film. 2 A second deposition step involves additionally depositing a tungsten film using magnetron sputtering with the above power density,

[0016] A tungsten film for a semiconductor device is provided, having a tungsten film quality in which the proportion of particles with a particle size of 0.12 μm or larger is 50% or more. [Effects of the Invention]

[0017] A tungsten film deposition method according to one embodiment of the present invention has the advantage of being able to control the particle size and particle orientation of the deposited tungsten thin film by replacing materials such as Cu that are already in use and classifying the PVD process into a first deposition step, a surface modification step, and a second deposition step.

[0018] In addition, by doing so, the particle size of the tungsten film can be increased compared to the existing PVD process, and a low specific resistance can be obtained by increasing the ratio of particles having (110) orientation. When applying the film formation method according to an embodiment of the present invention, since the internal tension is deformed and the inter-plane distances of each crystal grain become different, the stress of tungsten can also be controlled.

[0019] Furthermore, in the tungsten film formation process, by performing the first deposition step and the surface modification step 1 to 4 times before the second deposition step, or by adjusting the film formation conditions of tungsten (such as DC voltage, Ar, Kr flow rate, etc.), the effect of reducing the specific resistance can be adjusted to the most suitable shape, and the tungsten film obtained thereby exhibits excellent quality, which is effective.

[0020] The effects of the present invention are not limited to the above effects, and it should be understood that the effects include all effects that can be inferred from the configuration of the invention described in the detailed description or claims of the present invention.

Brief Description of the Drawings

[0021] [Figure 1] It is a diagram showing a tungsten film formation process according to an embodiment of the present invention. ​​​​​​​​​​​​​This figure shows the ratio of tungsten particles by size obtained through a tungsten film deposition process according to one embodiment of the present invention. [Figure 7] This figure shows the XRD (X-ray diffraction) measurement results of a tungsten film manufactured by a tungsten film deposition process according to one embodiment of the present invention. [Figure 8] This figure compares the EBSD (Electron Back Scatter Diffraction) measurement results of a tungsten film manufactured by a tungsten film deposition process according to one embodiment of the present invention and a tungsten film manufactured by an existing process. [Modes for carrying out the invention]

[0022] The embodiments will be described in detail below with reference to the attached drawings. However, various modifications may be made to the embodiments, and the scope of the patent application will not be limited or restricted by such embodiments. All modifications, equivalents, or substitutes to the embodiments should be understood to be included within the scope of the patent.

[0023] The terms used in the embodiments are for illustrative purposes only and should not be construed as limiting. Singular expressions include plural expressions unless, in context, they have a clearly different meaning. In this specification, terms such as “includes” or “has” indicate the presence of features, figures, steps, actions, components, parts, or combinations thereof described in the specification, and should not be understood as preemptively excluding the possibility of the presence or addition of one or more other features, figures, steps, actions, components, parts, or combinations thereof.

[0024] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as those commonly understood by a person of ordinary skill in the art to which this embodiment belongs. Commonly used predefined terms should be interpreted as having the meaning consistent with their meaning in the context of the relevant art, and not as ideal or overly formal unless expressly defined herein.

[0025] Furthermore, when explaining with reference to the attached drawings, the same components will be assigned the same reference numerals regardless of the reference numerals used in the drawings, and redundant explanations will be omitted. In the description of embodiments, if a specific explanation of related prior art is deemed to unnecessarily obscure the gist of the embodiment, such detailed explanation will be omitted.

[0026] According to one embodiment of the present invention, a method for depositing a tungsten (W) film on a semiconductor substrate using a physical vapor deposition (PVD) sputtering method,

[0027] a) 0.5 W / cm² on the semiconductor substrate 2 A first deposition step involves depositing a tungsten film using magnetron sputtering with a power density of less than 100%,

[0028] b) A step of modifying the surface of the deposited tungsten by performing RF biasing treatment in an inert gas atmosphere,

[0029] c) Apply 0.5 W / cm² to the deposited tungsten film. 2 A second deposition step involves additionally depositing a tungsten film using magnetron sputtering with the above power density,

[0030] A method for depositing a tungsten film on a semiconductor device is provided, characterized by including [the following].

[0031] In step a) above (first deposition step), DC power and RF power (RF stage biasing) are used to achieve a low power density (0.5 W / cm²). 2 A tungsten film can be deposited using a method less than 0.3 nm, and as a result, the thickness of the tungsten film formed on the semiconductor substrate may be 0.3 to 0.6 nm.

[0032] If the thickness of the tungsten film formed via the first deposition step is less than 0.3 nm or exceeds 0.6 nm, a problem arises in which the resistivity of the deposited tungsten film increases, as shown in Table 3 of the embodiment described below.

[0033] In the first deposition step, the DC power is preferably relatively low, specifically less than 1kW, for example, 0.2kW to 0.6kW, and more specifically, 0.4kW. The RF power applied simultaneously with the DC power can be in the range of 50W to 200W.

[0034] On the other hand, the semiconductor substrate used during tungsten film deposition is not limited to any particular type, as long as it is a wafer substrate with the same process effect; for example, an SiO2 wafer may be used.

[0035] Furthermore, step b) may be a surface modification step of the deposited tungsten, which is performed after the first tungsten deposition step a).

[0036] Step b) includes a process of applying only RF power without applying DC power, and forming a plasma of the gas using an inert gas containing one or more selected from the group consisting of Ar, Kr, Ne, and Xe. Here, considering the effective aspects of the invention, the use of Kr gas is preferable to Ar gas, but the type is not greatly limited.

[0037] Furthermore, the RF power may be 50W to 200W, and this is characterized by performing RF biasing treatment for approximately 2 to 10 seconds. This has the advantage of improving the interface of the tungsten film.

[0038] On the other hand, in the tungsten film deposition method for a semiconductor device according to one embodiment of the present invention, steps a) and b) may be performed not only once but up to four times. This allows the tungsten film deposited first to have a thickness of 0.3 nm to 2.4 nm.

[0039] In this way, by performing the first deposition step (step a)) and the surface modification step (step b)) one to four times, the interface of the seed layer can be improved, increasing the particle size of the manufactured tungsten film and improving its resistivity.

[0040] If steps a) and b) are not performed (0 times), or if the number of repetitions of steps a) and b) exceeds 4, the resistivity of the tungsten film increases, as shown in Figure 3, resulting in a problem where it is unsuitable for semiconductor elements used in small devices. In particular, when steps a) and b) are repeated 5, 8, and 12 times, the resistivity is significantly higher, to the extent that there is not much difference compared to the case where only the second deposition process is performed (steps a) and b) are not performed) (Figure 3).

[0041] Furthermore, through the repeatedly performed first deposition step and surface modification step, stress is formed in the attractive direction while controlling the initial interface of the tungsten, making it possible to obtain a film with stress close to zero in the compressed film.

[0042] On the other hand, the method for depositing a tungsten film of a semiconductor device according to one embodiment of the present invention involves performing steps a) and b) which are repeated 1 to 4 times, followed by a high power density (0.5 W / cm²). 2A second deposition step (step c)) of additionally depositing a tungsten film on the deposited tungsten film using magnetron sputtering as described above may be included.

[0043] Thereby, the tungsten film can be deposited to a desired thickness at one time, where the thickness of the tungsten film to be deposited is not greatly limited.

[0044] On the other hand, when considering the specific resistance of the formed tungsten film, it is preferable that the DC power applied in the first deposition step of step a) is smaller than or the same as the DC power applied in the second deposition step of step c).

[0045] As shown in FIG. 5 below, in the case where the DC power applied in the first deposition step is larger than the DC power applied in the second deposition step, a specific resistance similar to that of an existing process in which only the second deposition step is performed is measured, and it can be seen that a somewhat larger specific resistance is shown. As the specific DC power applied in the second deposition step, it may be 1.0 kW or more, and as an example, it 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.

[0046] All of the steps a), b), and c) are performed in a chamber where physical vapor deposition sputtering is performed, and the pressure condition of the chamber is preferably 1 Pa or less.

[0047] According to another embodiment of the present invention, a tungsten film of a semiconductor device manufactured by a tungsten film forming method including the following steps a) to c),

[0048] a) A first deposition step of depositing a tungsten film using magnetron sputtering with a power density of less than 0.5 W / cm 2 on the semiconductor substrate, and

[0049] b) A step of modifying the surface of the deposited tungsten by performing RF biasing treatment in an inert gas atmosphere,

[0050] c) Apply 0.5 W / cm² to the deposited tungsten film. 2 A second deposition step involves additionally depositing a tungsten film using magnetron sputtering with the above power density,

[0051] A tungsten film for a semiconductor device is provided, having a tungsten film quality in which the proportion of particles with a particle size of 0.12 μm or larger is 50% or more.

[0052] The process for manufacturing the tungsten film of the semiconductor device is substantially the same as the process described in detail above, and unlike existing processes that only perform the second deposition step, the proportion of particles with a particle size of 0.12 μm or larger in the manufactured tungsten film may be 50% or more. In contrast, in existing processes that only perform the second deposition step, the proportion of particles with a particle size of 0.12 μm or larger is only about 9%, showing a significant difference in tungsten film quality (Figure 6).

[0053] In addition, as shown in Figure 7, the tungsten film manufactured by one embodiment of the present invention exhibits a 110 peak shift compared to the existing process, which means that the interplane distances of the crystal grains within the film differ, resulting in the generation of tensile stress within the film. Furthermore, compared to the existing process, the number of crystal grains exhibiting (110) orientation increases, and it is possible to obtain a tungsten film in which this ratio exceeds 50%, resulting in an improved resistivity (Figure 8).

[0054] The present invention will be described in more detail below with reference to embodiments. The embodiments described below are for illustrative purposes only and do not limit the scope of the present invention.

[0055] <Embodiment>

[0056] 1. Method for depositing tungsten films on semiconductor devices

[0057] - Embodiment 1

[0058] 1) First deposition process of tungsten (W)

[0059] Using the ULVAC ENTRON#1 test equipment, a physical vapor deposition (PVD) sputtering system was used to deposit films on a substrate.

[0060] A DC power of 0.4 kW and RF biasing are simultaneously applied to an SiO2 semiconductor substrate, resulting in a low power density (Low Power Density; 0.5 W / cm²). 2 A tungsten film with a thickness of 0.5 nm was deposited (less than ).

[0061] 2) RF biasing process

[0062] An inert gas was supplied into the chamber, and with no DC power applied, only RF power of 50W to 200W was applied to the Stage for 5 seconds to form an inert gas plasma. After that, the fabricated tungsten film was subjected to RF biasing treatment.

[0063] 3) Second deposition process of tungsten (W)

[0064] The 1.2 kW DC power and RF biasing are applied to the RF-biased tungsten film, resulting in a high power density (Low Power Density; 0.5 W / cm²). 2 (The above steps) were followed by the deposition of an additional tungsten film with a thickness of approximately 38 nm, ultimately producing a tungsten film with a thickness of 38.52 nm.

[0065] - Embodiments 2-3 (Changes in the number of first deposition operations)

[0066] Apart from the fact that the first tungsten deposition process and the RF biasing process were performed twice (Embodiment 2) and four times (Embodiment 3), the tungsten film was manufactured in the same manner as in Embodiment 1, and as a result, tungsten films with thicknesses of 38.13 nm and 37.74 nm were obtained, respectively.

[0067] -Comparative example 1 (Normal Deposition)

[0068] On an SiO-2 substrate, the first tungsten (W) deposition process and the RF biasing process of Embodiment 1 were not performed, and only the second deposition process was carried out using 1.2 kW of DC power. As a result, a tungsten film with a total thickness of 38.8 nm was obtained.

[0069] - Comparative Example 2

[0070] On an SiO-2 substrate, the RF biasing process of Embodiment 1 was omitted, and only the first and second tungsten (W) deposition processes were carried out. As a result, a tungsten film with a total thickness of 37.3 nm was obtained.

[0071] - Comparative Examples 3-5 (Changes in the number of first deposition cycles)

[0072] Except for performing the first tungsten deposition step and RF biasing treatment step five times (Comparative Example 3), eight times (Comparative Example 4), and twelve times (Comparative Example 5) respectively, tungsten films were manufactured in the same manner as in Embodiment 1, and as a result, tungsten films with thicknesses of 38.2 nm, 38.39 nm, and 37.70 nm were obtained.

[0073] The resistivity of each tungsten film produced according to Embodiments 1-3 and Comparative Examples 1-5 was measured and is shown in Table 1 and Figure 3 below.

[0074] [Table 1]

[0075] 2. Resistivity measurement results for each DC power level

[0076] - Embodiment 4 (DC power in the first deposition step < DC power in the second deposition step)

[0077] Except for varying the process time in the second tungsten (W) deposition step to obtain a tungsten film with a final thickness of 50.16 nm, the first deposition step, RF biasing step, and second deposition step were carried out in the same manner as in Embodiment 3, and as a result, a tungsten film having a resistivity of 8.47 μΩcm was manufactured.

[0078] - Embodiment 5 (DC power in the first deposition step = DC power in the second deposition step)

[0079] Except for using a DC power of 1.2 kW in the first deposition step of tungsten (W), the tungsten film was manufactured in the same manner as in Embodiment 4, and as a result, a tungsten film with a thickness of 51.24 nm and a resistivity of 9.71 μΩcm was obtained.

[0080] - Comparative Example 6 (DC power in the first deposition step > DC power in the second deposition step)

[0081] Except for using a DC power of 1.6 kW in the first deposition step of tungsten (W), the tungsten film was manufactured in the same manner as in Embodiment 4, and as a result, a tungsten film with a thickness of 53.96 nm and a resistivity of 10.02 μΩcm was obtained.

[0082] -Comparative example 7 (Normal Deposition)

[0083] In contrast to Embodiments 4 and 5 and Comparative Example 6, a tungsten film with a total thickness of 50.14 nm was obtained by performing only the second deposition process using 1.2 kW of DC power on an SiO-2 substrate, without performing the first deposition process and the RF biasing process of tungsten (W). The resistivity measurement of the tungsten film showed a result of 10.18 μΩcm.

[0084] The power size and resistivity of the tungsten films produced through Embodiments 4-5 and Comparative Examples 6-7 are compared and shown in Table 2 and Figure 5 below.

[0085] [Table 2]

[0086] 3. Analysis of resistivity change for each film thickness per first deposition step

[0087] In the first deposition step, the thickness of the film deposited each time was varied by 0.1 nm, 0.3 nm, 0.4 nm, 0.5 nm, 0.6 nm, 0.9 nm, and 1.0 nm, respectively. The first deposition step was repeated four times in the same manner as in Embodiment 3, and after RF bias treatment, the second deposition step was performed to form a tungsten film.

[0088] The resistivity was measured and summarized in Table 3 below.

[0089] [Table 3]

[0090] Therefore, it can be seen that if the thickness of the tungsten film formed via the first deposition step is less than 0.3 nm or exceeds 0.6 nm, the resistivity of the deposited tungsten film increases.

[0091] 4. Analysis of particle size and orientation

[0092] - Grain size and portion analysis by size (Figure 6)

[0093] EBSD (Electron Back Scatter Diffraction) is one method of analyzing the orientation of crystal grains within a specimen by analyzing the diffraction pattern of backscattered electrons in a tungsten film formed by an existing process (Comparative Example 1) and an improved process according to one embodiment of the present invention (Embodiment 3) using an ultra-high-resolution field emission scanning transfer microscope (FESEM) JSM-IT800. Measurements and analyses were performed. The surface grain size was calculated via EBSD, and the portion for each grain size is shown (Figure 6).

[0094] As a result, it can be seen that in the tungsten film produced by Comparative Example 1 (existing process), the proportion of particles with a particle size of 0.12 μm or larger was only about 9%, while in the tungsten film produced by Embodiment 3 (improved process), the proportion of particles with a particle size of 0.12 μm or larger was 51.9%.

[0095] - XRD (X-ray diffraction) measurement and analysis (Figure 7 and Table 4)

[0096] To analyze the properties of the crystalline material, XRD (X-ray diffraction) analysis was performed on tungsten films formed by an existing process (Comparative Example 1) and an improved process according to one embodiment of the present invention (Embodiments 2 and 3) using an XRD Rigaku SmartLab (9kW) instrument (Figure 7).

[0097] As a result, it was found that the position of the W(110)Peak in the tungsten films produced by Embodiments 2 and 3 was shifted compared to the tungsten film produced by Comparative Example 1, indicating that there was a change in stress.

[0098] [Table 4]

[0099] - Calculation of grain orientation and ratio of tungsten film (Figure 8)

[0100] EBSD measurements and analyses were performed on tungsten films formed by an existing process (Comparative Example 1) and an improved process according to one embodiment of the present invention (Embodiment 3), in the same manner as in Figure 6. The ratio of grain orientation to orientation was calculated via the EBSD, and the increase in grain size was observed (Figure 8).

[0101] As a result, in the tungsten film produced by Comparative Example 1 (existing process), the proportion of particles having (110) orientation was 46.24%, while in the tungsten film formed by Embodiment 3, the proportion of particles having (110) orientation was 54.30%, indicating that the improved process increased the (110) orientation by approximately 8% compared to the existing process. Furthermore, the grain size was found to be even larger in the improved process (Embodiment 3).

[0102] Although embodiments of the present invention have been described in detail above with reference to the drawings, the present invention is not limited to the embodiments described above, and a person with ordinary skill in the art can apply various technical modifications and variations based on the above. For example, the described techniques may be performed in a different order than described, and / or the described components may be combined or assembled in a different manner than described, or substituted or replaced by other components or equivalents, and appropriate results may still be achieved.

[0103] Therefore, other realizations, other embodiments, and those equivalent to the claims described below also fall within the scope of the claims.

Claims

1. As a method for depositing tungsten (W) films on semiconductor substrates using physical vapor deposition (PVD) sputtering, a) 0.5 W / cm² on the semiconductor substrate ２ A first deposition step involves depositing a tungsten film using magnetron sputtering with a power density of less than 100%, b) A step of modifying the surface of the deposited tungsten by performing RF biasing treatment under an inert gas atmosphere, c) 0.5 W / cm² on the deposited tungsten film ２ A second deposition step involves additionally depositing a tungsten film using magnetron sputtering with the above power density, A method for depositing a tungsten film on a semiconductor device, characterized by including the following:

2. The method for depositing a tungsten film 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 method for forming a tungsten film of a semiconductor device according to claim 1, characterized in that steps a) and b) are performed one to four times prior to step c).

4. The method for depositing a tungsten film for a semiconductor device according to claim 3, characterized in that the thickness of the tungsten film deposited via steps a) and b) is 0.3 to 2.4 nm.

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

6. A method for depositing a tungsten film on a semiconductor device according to claim 1, characterized in that the DC power applied in step a) is less than 1.0 kW, and the DC power applied in step c) is 1.0 kW or more and less than 3.0 kW.

7. The method for depositing a tungsten film of a semiconductor device according to claim 1, wherein the inert gas in step b) comprises one or more selected from the group consisting of Ar, Kr, Ne, and Xe.

8. The method for depositing a tungsten film on a semiconductor device according to claim 1, characterized in that the RF biasing process in step b) is performed at a power of 50W to 200W for a period of 2 to 10 seconds.

9. The method for depositing a tungsten film on a semiconductor device according to claim 1, wherein the DC power in step b) is not applied, and only RF bias is applied to perform plasma processing.

10. The method for depositing a tungsten film on the semiconductor device according to claim 1, wherein the method is carried out in a physical vapor deposition (PVD) chamber with a pressure of 1 Pa or less.

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