Thin film formation method

Abstract

The present invention relates to a method for forming a thin film, and more particularly to a method for forming a tungsten thin film, the method comprising the steps of supplying a reducing gas onto a substrate disposed in a reaction space, supplying power to generate plasma in the reaction space, and supplying a tungsten-containing gas onto the substrate, the step of supplying the tungsten-containing gas being performed intermittently while the reducing gas is being supplied.

Description

[Technical Field]

[0001] The present invention relates to a method for forming a thin film, and more particularly to a method for forming a thin film of tungsten. [Background technology]

[0002] Tungsten thin films have low resistance and high thermal stability, and are therefore widely used in electrodes and wiring structures in semiconductor elements and electronic devices.

[0003] Tungsten thin films can be formed on substrates or semiconductor layers using methods such as chemical vapor deposition (CVD) or atomic layer deposition (ALD). When a gaseous source material is used to form a tungsten thin film, it has the characteristic of providing excellent step coverage in stepped structures with a high aspect ratio.

[0004] To form a tungsten thin film, a tungsten-containing material that acts as a nucleation or seed layer is deposited on a substrate, and a remaining tungsten layer acting as a bulk layer is deposited on top of the nucleation or seed layer. Such tungsten thin films are typically fabricated by reducing tungsten hexafluoride (WF), a fluorine-based tungsten material, using hydrogen (H) as a reducing agent in a chemical vapor deposition process.

[0005] However, when tungsten hexafluoride (WF6) is used to form a tungsten thin film, fluorine (F) remains as an impurity on the surface and inside of the formed tungsten thin film. The remaining fluorine (F) may cause electromigration or diffusion to adjacent components, damaging contacts and reducing the overall performance of the semiconductor device. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Republic of Korea Publication Patent No. 10-2017-0120443 Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention provides a method for forming a thin film that can form a tungsten thin film with a reduced impurity concentration. [Means for solving the problem]

[0008] A method for forming a thin film according to an embodiment of the present invention includes the steps of supplying a reducing gas onto a substrate placed in a reaction space, supplying power to generate plasma in the reaction space, and supplying a tungsten-containing gas onto the substrate, wherein the step of supplying the tungsten-containing gas is performed intermittently while the reducing gas is being supplied.

[0009] The reducing gas and the tungsten-containing gas may be supplied onto the substrate through separate paths.

[0010] The step of supplying power may be performed intermittently while the reducing gas is being supplied, and the step of supplying the tungsten-containing gas may be performed while power is being supplied to generate plasma in the reaction space.

[0011] The step of supplying power may be initiated before supplying the tungsten-containing gas.

[0012] The method may further include supplying a silicon-containing gas onto the substrate before supplying the reducing gas.

[0013] The step of supplying the silicon-containing gas may be terminated before supplying the reducing gas.

[0014] The step of supplying power may be terminated when the supply of the tungsten-containing gas is interrupted.

[0015] The method may further include purging the reaction space while the power is not applied.

[0016] Furthermore, a method for forming a thin film according to an embodiment of the present invention includes the steps of supplying a reducing gas onto a substrate disposed in a reaction space, depositing a tungsten thin film on the substrate, and removing impurities remaining in the tungsten thin film, and the steps of depositing the tungsten thin film and removing the impurities may be performed alternately while supplying the reducing gas.

[0017] The step of depositing the tungsten thin film may be performed by generating a plasma in the reaction space and supplying a tungsten-containing gas onto the substrate.

[0018] The reducing gas and the tungsten-containing gas may be supplied onto the substrate through separate paths.

[0019] The method may further include forming a silicon layer on the substrate before supplying the reducing gas.

[0020] The step of depositing the tungsten thin film may be performed by substituting tungsten atoms for silicon atoms contained in the silicon layer.

[0021] The step of removing the impurities may be performed by generating a plasma in the reaction space and stopping the supply of a tungsten-containing gas above the substrate.

[0022] The method may further include a step of purging the reaction space between the step of depositing the tungsten thin film and the step of removing impurities.

[0023] The step of purging the reaction space may be performed without generating a plasma in the reaction space.

[0024] The reducing gas may include hydrogen gas, the tungsten-containing gas may include tungsten hexafluoride gas, and the impurities may include a fluorine component. [Effects of the Invention]

[0025] According to the thin film forming method of the embodiment of the present invention, a tungsten thin film is formed by alternately repeating the steps of depositing a tungsten layer and removing impurities contained in the deposited tungsten layer, thereby making it possible to form a tungsten thin film with reduced thin film stress and impurity concentration.

[0026] In addition, by purging the reaction space before removing impurities contained in the tungsten layer, the efficiency of the impurity removal step can be improved and the content of fluorine components can be reduced to a low fluorine tungsten (LWF) level, which is a level that cannot be detected by component analysis. [Brief explanation of the drawings]

[0027] [Figure 1] 1 is a diagram schematically illustrating a substrate processing apparatus according to an embodiment of the present invention. [Figure 2] FIG. 2 is a diagram schematically illustrating a gas injection unit according to an embodiment of the present invention. [Figure 3] FIG. 3 is an exploded view of the gas injection unit shown in FIG. 2. [Figure 4] 1 illustrates how a plasma is formed according to an embodiment of the present invention; [Figure 5] 1A to 1C are diagrams schematically illustrating a method for forming a thin film according to an embodiment of the present invention. [Figure 6] 1A to 1C are diagrams for explaining a process cycle of a thin film forming method according to an embodiment of the present invention. [Figure 7] 1A to 1C are diagrams for explaining steps in which a thin film is formed within a process cycle. DETAILED DESCRIPTION OF THE INVENTION

[0028] Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, and may be embodied in various different forms. These embodiments are provided merely to complete the disclosure of the present invention and to fully convey the scope of the invention to those skilled in the art.

[0029] Throughout the specification, when a component, such as a layer, film, region, or substrate, is referred to as being "on" another component, it can be interpreted as meaning that the component may be directly "on" and in contact with the other component, or that there may be further components interposed therebetween.

[0030] Additionally, relative terms such as "upper" or "lower" may be used in this disclosure to describe the relative relationship of one element to another element, as illustrated. It will be understood that the relative terms are intended to include other orientations of the elements in addition to the orientation depicted in the figures. The drawings may be exaggerated to better illustrate the invention, and like numerals throughout the drawings refer to like elements.

[0031] Fig. 1 is a diagram schematically illustrating a substrate processing apparatus according to an embodiment of the present invention. Fig. 2 is a diagram schematically illustrating a gas injection unit according to an embodiment of the present invention, and Fig. 3 is an exploded view of the gas injection unit shown in Fig. 2. Meanwhile, Fig. 4 is a diagram illustrating how plasma is generated according to an embodiment of the present invention.

[0032] 1 to 4, a substrate processing apparatus according to an embodiment of the present invention is an apparatus for forming a thin film, for example, a tungsten thin film, and includes a chamber 10, a substrate support unit 20 disposed within the chamber 10 for supporting a substrate S disposed within the chamber 10, a gas injection unit 30 disposed within the chamber 10 facing the substrate support unit 20 for injecting a process gas toward the substrate support unit 20, and a gas supply unit 40 for supplying gas to the gas injection unit 30. The substrate processing apparatus may further include an RF power supply 50 for supplying power to generate plasma within the chamber 10 and a control unit (not shown) for controlling the RF power supply 50. Here, the gas injection unit 30 is provided with a first gas supply path for supplying a first gas and a second gas supply path for supplying a second gas, which are separated from each other.

[0033] The chamber 10 provides a predetermined reaction space and keeps it airtight. The chamber 10 may include a body 12 having a generally circular or rectangular flat surface and a sidewall extending upward from the flat surface to define the predetermined reaction space, and a generally circular or rectangular lid 14 positioned on the body 12 to keep the reaction space airtight. However, the chamber 10 is not limited thereto and may be fabricated in a variety of shapes corresponding to the shape of the substrate S.

[0034] An exhaust port (not shown) may be formed in a predetermined region of the bottom surface of the chamber 10, and an exhaust pipe (not shown) connected to the exhaust port may be provided on the outside of the chamber 10. The exhaust pipe may also be connected to an exhaust device (not shown). A vacuum pump such as a turbomolecular pump can be used as the exhaust device. Therefore, the inside of the chamber 10 can be evacuated to a predetermined reduced pressure atmosphere, for example, a predetermined pressure of 0.1 mTorr or less, using the exhaust device. The exhaust pipe may be provided not only on the bottom surface of the chamber 10, but also on the side surface of the chamber 10 below the substrate support part 20 (described later). Needless to say, multiple exhaust pipes and associated exhaust devices may be provided to shorten the exhaust time.

[0035] Meanwhile, a substrate S disposed within the chamber 10 for the thin film formation process may be placed on the substrate support unit 20. Here, the substrate S may be a substrate on which a tungsten layer serving as a nucleation layer or seed layer is deposited to form a tungsten thin film, or a substrate on which a nucleation layer or seed layer has already been formed to form a tungsten layer as a bulk layer thereon. The substrate support unit 20 may be provided with, for example, an electrostatic chuck or the like to adsorb and hold the substrate S by electrostatic force, or may support the substrate S by vacuum adsorption or mechanical force.

[0036] The substrate support unit 20 may have a shape corresponding to the shape of the substrate S, for example, a circular or rectangular shape. The substrate support unit 20 may include a substrate support stage 22 on which the substrate S is placed, and an elevator 24 disposed below the substrate support stage 22 to raise and lower the substrate support stage 22. The substrate support stage 22 may be larger than the substrate S, and the elevator 24 may be disposed to support at least one region, for example, the center, of the substrate support stage 22. Once the substrate S is placed on the substrate support stage 22, the elevator 24 may move the substrate support stage 22 closer to the gas injection unit 30. A heater (not shown) may be disposed inside the substrate support stage 22. The heater generates heat at a predetermined temperature to heat the substrate support stage 22 and the substrate S placed on the substrate support stage 22, thereby ensuring uniform deposition of a thin film on the substrate S.

[0037] The gas supply unit 40 may be disposed to penetrate the lid 14 of the chamber 10 and may include a first gas supplier 42 and a second gas supplier 44 to supply a first gas and a second gas, respectively, to the gas injection unit 30. Here, the first gas may include a tungsten-containing gas, and the second gas may include a reducing gas. Conversely, it goes without saying that the first gas may include a reducing gas, and the second gas may include a tungsten-containing gas. Furthermore, the tungsten-containing gas may include tungsten hexafluoride (WF) gas, and the reducing gas may include hydrogen (H). Meanwhile, the first gas supplier 42 and the second gas supplier 44 do not necessarily supply a single type of gas. The first gas supplier 42 and the second gas supplier 44 may each be configured to simultaneously supply multiple types of gases or to supply a gas selected from multiple types of gases.

[0038] The gas injection unit 30 is disposed inside the chamber 10, for example, on the underside of the lid 14, and a first gas supply path for injecting and supplying a first gas onto the substrate and a second gas supply path for injecting and supplying a second gas onto the substrate are formed inside the gas injection unit 30. The first gas supply path and the second gas supply path may be formed to be independent and separated from each other, so that the first gas and the second gas are supplied separately onto the substrate to prevent mixing within the gas injection unit 30.

[0039] The gas injection unit 30 may include an upper frame 32 and a lower frame 34. The upper frame 32 is detachably coupled to the lower surface of the lid 14, and a portion of the upper surface, for example, the center of the upper frame 32, is spaced a predetermined distance from the lower surface of the lid 14. This allows a first gas from a first gas supply unit 42 to be distributed throughout the space between the upper surface of the upper frame 32 and the lower surface of the lid 14. The lower frame 34 is disposed at a predetermined distance from the lower surface of the upper frame 32. This allows a second gas from a second gas supply unit 44 to be distributed throughout the space between the upper surface of the lower frame 34 and the lower surface of the upper frame 32. The upper frame 32 and the lower frame 34 may be integrally formed, connected along their outer peripheries to form an internally separated space, or may be configured such that the outer peripheries are sealed by a separate sealing member.

[0040] The first gas supply path may be formed so that a first gas from a first gas supply unit 42 spreads throughout the space between the lower surface of the cover 14 and the upper frame 32, passes through the upper frame 32 and the lower frame 34, and is supplied into the chamber 10. The second gas supply path may be formed so that a second gas from a second gas supply unit 44 spreads throughout the space between the lower surface of the upper frame 32 and the upper surface of the lower frame 34, passes through the lower frame 34, and is supplied into the chamber 10. The first gas supply path and the second gas supply path do not need to be connected to each other, so that the first gas and the second gas can be supplied separately from the gas supply unit 40 to the chamber 10 via the gas injection unit 30.

[0041] A first electrode 38 may be disposed on the lower surface of the lower frame 34, and a second electrode 36 may be disposed at a predetermined distance below the lower frame 24 and outside the first electrode 28. In this case, it goes without saying that the lower frame 34 and the second electrode 36 may be formed so as to be connected along the outer circumferential surface, or may be configured so as to seal the outer circumferential surface with a separate sealing member.

[0042] In this manner, when the first electrode 38 and the second electrode 36 are arranged, the first gas can be injected onto the substrate through the first electrode 38, and the second gas can be injected onto the substrate through the separation space between the first electrode 38 and the second electrode 36.

[0043] RF power may be applied to either the lower frame 34 or the second electrode 36 from an RF power supply 50. FIG. 4 shows an example in which the lower frame 34 is grounded and RF power is applied to the second electrode 36. When the lower frame 34 is grounded, the first electrode 38 disposed on the lower surface of the lower frame 34 is also grounded. Therefore, when RF power from the RF power supply 50 is applied to the second electrode 36, a first activation region, i.e., a first plasma region P1, is formed between the gas injection unit 30 and the substrate support unit 20, and a second activation region, i.e., a second plasma region P2, is formed between the first electrode 38 and the second electrode 36.

[0044] Fig. 4 is a diagram showing how plasma is formed according to an embodiment of the present invention. Fig. 4 shows an example in which the first electrode 38 and the substrate support 20 are grounded and RF power is applied to the second electrode 36 from the RF power supply 50, but it goes without saying that the power supply mechanism is not limited to this.

[0045] 4, a first gas, for example, a tungsten-containing gas, may be supplied into the chamber 10 along the solid arrow, and a second gas, for example, a reducing gas, may be supplied into the chamber 10 along the dotted arrow. The first gas may be supplied into the chamber 10 through the first electrode 38, and the second gas may be supplied into the chamber 10 through the space between the first electrode 38 and the second electrode 36. The first gas may be supplied into the chamber 10 through the first electrode 38.

[0046] When the first electrode 38 and the substrate support 20 are grounded and power is supplied to the second electrode 36, a first activation region, i.e., a first plasma region P1, is formed between the gas injection unit 30 and the substrate support 20, and a second activation region, i.e., a second plasma region P2, is formed between the first electrode 38 and the second electrode 36.

[0047] Therefore, when the first gas is supplied through the first electrode 38, the first gas is activated in a first plasma region P1 formed outside the gas injection unit 30. When the second gas is supplied through the space between the first electrode 38 and the second electrode 36, the second gas is activated in the region between the first electrode 38 and the second electrode 36, which corresponds to the interior of the gas injection unit 30, i.e., the region from the second plasma region P2 to the first plasma region P1. Therefore, the substrate processing apparatus according to the embodiment of the present invention can activate the first gas and the second gas in plasma regions of different sizes. By activating the first gas and the second gas in plasma regions of different sizes, each gas can be distributed to an optimal supply path for depositing a thin film.

[0048] 5 and 6, the thin film forming method of the present invention will be described in detail. In describing the thin film forming method according to the embodiment of the present invention, descriptions that overlap with the description of the substrate processing apparatus described above will be omitted.

[0049] FIG. 2 is a diagram illustrating a schematic diagram of a method for forming a thin film according to an embodiment of the present invention, FIG. 3 is a diagram illustrating a process cycle of the method for forming a thin film according to an embodiment of the present invention, and FIG. 4 is a diagram illustrating each step in the process cycle for forming a thin film.

[0050] 2 to 4, a method for forming a thin film according to an embodiment of the present invention includes a step (S100) of supplying a reducing gas onto a substrate S disposed in a reaction space, a step (S200) of supplying power to generate plasma in the reaction space, and a step (S300) of supplying a tungsten-containing gas onto the substrate S, wherein the step (S300) of supplying the tungsten-containing gas is performed intermittently while the reducing gas is being supplied.

[0051] In the step of supplying a reducing gas (S100), the reducing gas is supplied onto the substrate S provided in the reaction space of the chamber 10. In the step of supplying a reducing gas (S100), the supply of the reducing gas may be continued until the tungsten thin film is formed in the thin film forming method according to the embodiment of the present invention. Here, the reducing gas may be a gas containing hydrogen (H), for example, hydrogen (H2) gas.

[0052] In the step of supplying a reducing gas (S100), the reducing gas may be supplied onto the substrate S before the tungsten-containing gas is supplied, and the supply of the reducing gas may be continued until a tungsten thin film is formed. Here, a reducing gas, such as hydrogen (H) gas, supplied before the tungsten-containing gas, such as tungsten hexafluoride (WF) gas, is supplied can form a reducing atmosphere in the reaction space within the chamber 10. By forming a reducing atmosphere in the reaction space within the chamber 10 with hydrogen (H) gas before the tungsten hexafluoride (WF) gas is supplied, the tungsten hexafluoride (WF) gas can react with the hydrogen (H) gas or hydrogen (H) radicals activated by plasma in the space between the gas injection unit 30 and the substrate S, thereby primarily removing fluorine (F) components in the tungsten hexafluoride (WF) gas.

[0053] Meanwhile, as described above, the substrate S may be a substrate onto which a tungsten layer that functions as a nucleation layer or seed layer is deposited to form a tungsten thin film, or it may be a substrate on which a nucleation layer or seed layer has already been formed to form a tungsten layer as a bulk layer on the nucleation layer or seed layer.

[0054] In the step of supplying power (S200), high frequency power is supplied from the RF power supply 50 to generate plasma in the reaction space. In the step of supplying reducing gas (S100), when hydrogen (H2) gas is supplied as the reducing gas, the hydrogen (H2) gas can be activated into hydrogen (H) radicals by the plasma generated in the reaction space in the step of supplying power (S200).

[0055] In the step (S300) of supplying a tungsten-containing gas, the tungsten-containing gas is supplied onto the substrate S. Here, the tungsten-containing gas may include a gas containing tungsten (W), for example, tungsten hexafluoride (WF6) gas.

[0056] Here, when high frequency power is supplied from RF power supply 50 in power supply step (S200) and the tungsten-containing gas is supplied onto substrate S in tungsten-containing gas supply step (S300), there is a general problem that tungsten (W) may be deposited within gas injection unit 30. That is, when high frequency power is supplied to a typical showerhead-type gas injection unit 30 and a first gas, i.e., a tungsten-containing gas, and a second gas, i.e., a reducing gas, are supplied via gas injection unit 30, there is a concern that the tungsten-containing gas and the reducing gas may react with each other within gas injection unit 30, resulting in the deposition of tungsten (W) within gas injection unit 30.

[0057] However, as described above, in the gas injection unit 30 according to the embodiment of the present invention, the first gas supply path and the second gas supply path are not connected to each other but are formed to be independent and separated from each other. Therefore, the tungsten-containing gas supplied via the first electrode 38 shown in FIG. 4 does not react with the reducing gas supplied between the first electrode 38 and the second electrode 36 in the gas injection unit 30, but reacts with the reducing gas only at the bottom of the gas injection unit 30, effectively preventing tungsten (W) from being deposited in the gas injection unit 30.

[0058] Meanwhile, as described above, the step of supplying the reducing gas (S100) continues, and if the step of supplying the tungsten-containing gas (S300) is performed while the reducing gas is being supplied, the tungsten hexafluoride (WF) gas reacts with the hydrogen (H) gas according to the following reaction formula 1 and is reduced, thereby forming a tungsten layer on the substrate S.

[0059]

number

[0060] Here, the step of supplying the tungsten-containing gas (S300) may be performed intermittently during the supply of the reducing gas. That is, the step of supplying the reducing gas (S100) may be continued until the tungsten thin film is formed, and the step of supplying the tungsten-containing gas (S300) may be performed intermittently during the step of supplying the reducing gas (S100) so that the supply and interruption of the tungsten-containing gas are alternately performed during the supply of the reducing gas.

[0061] At this time, in a section where a hydrogen-containing gas, i.e., hydrogen (H2) gas, and a tungsten-containing gas, i.e., tungsten hexafluoride (WF6) gas, are simultaneously supplied onto the substrate S, the tungsten hexafluoride (WF6) gas and the hydrogen (H2) gas react with each other as shown in the above reaction formula, thereby depositing a tungsten thin film on the substrate S. That is, in a section where hydrogen (H2) gas and tungsten hexafluoride (WF6) gas are simultaneously supplied, the supplied tungsten hexafluoride (WF6) gas and the hydrogen (H2) gas react with each other to deposit a tungsten layer on the substrate S.

[0062] On the other hand, when the supply of the tungsten-containing gas is stopped and only hydrogen (H2) gas is supplied onto the substrate S, impurities, such as fluorine (F) components, in the tungsten layer formed on the substrate S are removed by the supplied hydrogen (H2) gas.

[0063] Even when tungsten hexafluoride (WF6) gas and hydrogen (H2) gas are supplied simultaneously to react with each other, the fluorine (F) component contained in the tungsten hexafluoride (WF6) is not sufficiently removed. Therefore, in a thin film formation method according to an embodiment of the present invention, the supply and interruption of tungsten hexafluoride (WF6) gas is repeated while supplying hydrogen (H2) gas, so that a tungsten layer is deposited in the section where hydrogen (H2) gas and tungsten hexafluoride (WF6) gas are supplied simultaneously, and in the section where only hydrogen (H2) gas is supplied alone, the deposited tungsten layer is treated with hydrogen (H2) gas to remove impurities, i.e., fluorine (F) components, contained in the deposited tungsten layer. As described above, in the embodiment of the present invention, by alternately performing the step of depositing a tungsten layer and the step of removing impurities from the deposited tungsten layer, the content of fluorine (F) in the tungsten layer can be reduced to a low fluorine tungsten (LWF) level, which is undetectable by elemental analysis.

[0064] Meanwhile, the method for forming a thin film according to an embodiment of the present invention may further include a step of supplying a silicon-containing gas onto the substrate S before supplying a reducing gas. That is, before supplying the reducing gas, a silicon layer may be formed on the substrate S, and then in the step of supplying a tungsten gas (S300), silicon atoms in the silicon layer may be replaced with tungsten atoms to deposit a tungsten thin film on the substrate S. In this case, the silicon-containing gas may include silane (SiH4) gas, and the silicon atoms in the silicone layer may be replaced with tungsten atoms by reacting with the tungsten-containing gas according to the following Reaction Scheme 2:

[0065]

number

[0066] In this case, the step of supplying the silicon-containing gas may be completed before the step of supplying the reducing gas (S100) is performed. Note that the step of supplying the silicon-containing gas may be performed only once before a process cycle including the step of supplying the reducing gas onto the substrate S provided in the reaction space (S100), the step of supplying power to generate plasma in the reaction space (S200), and the step of supplying the tungsten-containing gas onto the substrate S (S300), as will be described later, or may be included in the process cycle and repeatedly performed before the step of supplying the reducing gas (S100).

[0067] On the other hand, it goes without saying that the step of supplying power (S200) may be continued while hydrogen (H2) gas is being supplied, and in the section where hydrogen (H2) gas and tungsten hexafluoride (WF6) gas are simultaneously supplied, the hydrogen (H2) gas may be activated by plasma to hydrogen (H) radicals to react with the tungsten hexafluoride (WF6) gas, and in the section where only hydrogen (H2) gas is supplied, the hydrogen (H2) gas may be activated by plasma to hydrogen (H) radicals to treat the tungsten layer deposited on the substrate S with hydrogen (H2) gas.

[0068] However, the step of supplying power (S200) may be performed intermittently while supplying the reducing gas, and the step of supplying the tungsten-containing gas (S300) may be performed while supplying power to generate plasma in the reaction space. In this case, the embodiment of the present invention may further include a step of purging the reaction space while power is not being supplied.

[0069] When tungsten hexafluoride (WF6) gas is supplied intermittently, tungsten hexafluoride (WF6) remains in the reaction space even immediately after the supply of tungsten hexafluoride (WF6) gas is stopped. If tungsten hexafluoride (WF6) remains in the reaction space, if the supply of tungsten hexafluoride (WF6) gas is stopped and hydrogen (H2) gas is supplied, the supplied hydrogen (H2) gas will first react with the remaining tungsten hexafluoride (WF6) gas, resulting in insufficient treatment of the tungsten layer deposited on the substrate S.

[0070] Therefore, in an embodiment of the present invention, the step of supplying power (S200) is performed intermittently while the reducing gas is being supplied, and the reaction space is purged while power is not being supplied, thereby removing tungsten hexafluoride (WF6) gas remaining in the reaction space within the chamber 10.

[0071] After the supply of power is stopped and the reaction space is purged, the step of supplying power (S200) may be initiated before the tungsten-containing gas is supplied again. Here, only hydrogen (H2) gas is supplied to the reaction space after power is supplied and before the tungsten-containing gas is supplied again, and the supplied hydrogen (H2) gas is activated by plasma to treat the tungsten layer deposited on the substrate S and remove fluorine (F) contained in the tungsten layer. The step of supplying power (S200) may be terminated simultaneously with the interruption of the supply of the tungsten-containing gas, ensuring sufficient time for purging the reaction space.

[0072] Meanwhile, in the step of supplying the reducing gas (S100), the reducing gas may be supplied onto the substrate S before the tungsten-containing gas is supplied, and the supply of the reducing gas may be continued until a tungsten thin film is formed. Here, the reducing gas supplied before the tungsten-containing gas is supplied forms a reducing atmosphere in the reaction space within the chamber 10. Next, tungsten hexafluoride (WF6) gas is supplied as the tungsten-containing gas, and the hydrogen (H) component of the reducing gas continuously supplied to the reaction space combines with the fluorine (F) component contained in the tungsten hexafluoride (WF6) gas to generate hydrogen fluoride (HF) gas, which is then removed. As a result, a tungsten layer from which the fluorine (F) component has been primarily removed can be formed on the substrate S.

[0073] As shown in Figures 6 and 7, in an embodiment of the present invention, one process cycle consists of a period (section (1)) in which power is supplied while hydrogen (H) gas is being supplied and tungsten hexafluoride (WF) gas is being supplied to deposit a tungsten layer, and a period (section (2)) in which power is supplied while hydrogen (H) gas is being supplied and impurities are removed by supplying power without supplying tungsten hexafluoride (WF). It should be noted that a process cycle may also be formed by further including a period for purging the reaction space between the period (section (1)) in which the tungsten layer is deposited and the period (section (2)) in which the impurities are removed. The process cycle is repeated multiple times, and the periods for depositing the tungsten layer, purging the reaction space, and removing the impurities are repeatedly included, thereby effectively removing fluorine (F) from the tungsten layer and forming a tungsten thin film with a significantly reduced impurity concentration.

[0074] Thus, according to the thin film formation method of the embodiment of the present invention, a tungsten thin film can be formed by alternately repeating the steps of depositing a tungsten layer and removing impurities contained in the deposited tungsten layer, thereby forming a tungsten thin film with reduced thin film stress and impurity concentration.

[0075] In addition, by purging the reaction space before removing impurities contained in the tungsten layer, the efficiency of the impurity removal step can be improved, and the content of fluorine components can be reduced to a low fluorine tungsten (LWF) level, which is a level that cannot be detected by component analysis.

[0076] Although the preferred embodiments of the present invention have been described and illustrated using specific terms, it is clear that these terms are merely for the purpose of clarifying the present invention, and that various modifications and variations can be made to the embodiments of the present invention and the terms used without departing from the technical spirit and scope of the claims. In this manner, the modified and altered embodiments should not be understood separately from the spirit and scope of the present invention, but can be considered to fall within the scope of the claims of the present invention.

Claims

1. supplying a reducing gas onto a substrate disposed in a reaction space; providing a power source to generate a plasma in the reaction space; providing a tungsten-containing gas above the substrate; Including, The method for forming a thin film, wherein the step of supplying the tungsten-containing gas is performed intermittently while the reducing gas is being supplied.

2. 2. The method for forming a thin film according to claim 1, wherein the reducing gas and the tungsten-containing gas are supplied onto the substrate through paths separated from each other.

3. the step of supplying power is performed intermittently while the reducing gas is being supplied; 2. The method for forming a thin film according to claim 1, wherein the step of supplying the tungsten-containing gas is performed while supplying power to generate plasma in the reaction space.

4. 4. The method for forming a thin film according to claim 3, wherein the step of supplying power is initiated before the supply of the tungsten-containing gas.

5. 2. The method for forming a thin film according to claim 1, further comprising the step of supplying a silicon-containing gas onto the substrate before supplying the reducing gas.

6. 6. The method for forming a thin film according to claim 5, wherein the step of supplying the silicon-containing gas is terminated before the supply of the reducing gas.

7. 4. The method of forming a thin film according to claim 3, wherein the step of supplying power is terminated when the supply of the tungsten-containing gas is interrupted.

8. The method for forming a thin film according to claim 3 , further comprising the step of purging the reaction space while the power is not supplied.

9. supplying a reducing gas onto a substrate disposed in a reaction space; depositing a tungsten thin film on the substrate; removing impurities remaining in the tungsten thin film; Including, The method for forming a thin film, wherein the step of depositing the tungsten thin film and the step of removing the impurities are alternately performed while the reducing gas is being supplied.

10. 10. The method for forming a thin film according to claim 9, wherein the step of depositing the tungsten thin film is performed by generating plasma in the reaction space and supplying a tungsten-containing gas onto the substrate.

11. 11. The method for forming a thin film according to claim 10, wherein the reducing gas and the tungsten-containing gas are supplied onto the substrate through paths separated from each other.

12. The method for forming a thin film according to claim 9 , further comprising the step of forming a silicon layer on the substrate before supplying the reducing gas.

13. 13. The method of claim 12, wherein the step of depositing the tungsten thin film is performed by substituting tungsten atoms for silicon atoms contained in the silicon layer.

14. 11. The method for forming a thin film according to claim 10, wherein the step of removing the impurities is carried out by generating a plasma in the reaction space and stopping the supply of the tungsten-containing gas onto the substrate.

15. 11. The method of claim 10, further comprising the step of purging the reaction space between the step of depositing the tungsten thin film and the step of removing the impurities.

16. 16. The method for forming a thin film according to claim 15, wherein the step of purging the reaction space is performed without generating a plasma in the reaction space.

17. the reducing gas comprises hydrogen gas; the tungsten-containing gas includes tungsten hexafluoride gas, The method for forming a thin film according to claim 10 , wherein the impurities include a fluorine component.

Images