Thin film forming method

Abstract

This invention relates to a thin film formation method, particularly a thin film formation method for forming tungsten thin films. According to an exemplary embodiment, the thin film formation method includes supplying a reducing gas to a substrate located in a reaction space, applying a power source to generate plasma in the reaction space, and supplying a tungsten-containing gas to the substrate, wherein the supply of the tungsten-containing gas is performed intermittently while the reducing gas is being supplied.

Description

Technical Field

[0001] This invention relates to a thin film forming method, and more particularly to a thin film forming method for forming tungsten thin films. Prior Technology

[0002] Because of its low resistance and high thermal stability, tungsten thin films have been widely used in electrode or circuit structures in semiconductor components or electronic devices.

[0003] Tungsten thin films can be formed on substrates or semiconductor layers using methods such as chemical vapor deposition (CVD) and atomic layer deposition (ALD). When gaseous raw materials are used to form tungsten thin films, a good coating rate can be obtained in stepped structures with a large aspect ratio.

[0004] To form a tungsten thin film, a tungsten layer is deposited on a substrate as a nucleation layer or seed layer using a tungsten-containing material, and the remaining tungsten layers are deposited on the nucleation layer or seed layer as a bulk layer. Generally, tungsten thin films are produced through chemical vapor deposition by reducing tungsten hexafluoride gas (WF6), a fluorine-based tungsten material, using hydrogen (H2) as a reducing agent.

[0005] However, when tungsten hexafluoride gas (WF6) is used to form tungsten thin films, fluorine (F) can remain as an impurity inside and on the surface of the tungsten film. Residual fluorine (F) can lead to fluorine (F) diffusion or electromigration in adjacent components, and the overall performance of the semiconductor device may be reduced due to damage to the electrical contacts of the semiconductor device.

[0006] [Related Technical Documents]

[0007] [Patent Documents]

[0008] (Patent Document 1) KR10-2017-0120443 A Summary of the Invention

[0009] This invention provides a thin film forming method that can form tungsten thin films with reduced impurity concentration.

[0010] According to an exemplary embodiment, the thin film forming method includes: supplying a reducing gas to a substrate located in a reaction space, applying a power source to generate plasma in the reaction space, and supplying a tungsten-containing gas to the substrate, wherein the supply of the tungsten-containing gas is performed intermittently while the reducing gas is being supplied.

[0011] Reducing gas and tungsten-containing gas can be supplied to the substrate through independent pathways.

[0012] The power supply can be applied intermittently while the reducing gas is being supplied, and the supply of tungsten-containing gas can be carried out while the power supply is applied to generate plasma in the reaction space.

[0013] The application of power can begin before the supply of tungsten-containing gas.

[0014] This method can further include supplying a silicon-containing gas to the substrate before supplying the reducing gas.

[0015] The supply of silicon-containing gas can be completed before the supply of reducing gas.

[0016] The application of power can be completed when the supply of tungsten-containing gas is finished.

[0017] This method can be further incorporated into blowing out the reaction space when no power is applied.

[0018] According to another exemplary embodiment, the thin film forming method includes: supplying a reducing gas to a substrate located in a reaction space, depositing a tungsten thin film on the substrate, and removing a plurality of impurities remaining on the tungsten thin film, wherein the deposition of the tungsten thin film and the removal of the impurities are performed alternately while the reducing gas is supplied.

[0019] The deposition of tungsten thin films can be achieved by generating plasma in the reaction space and supplying a tungsten-containing gas onto the substrate.

[0020] Reducing gas and tungsten-containing gas can be supplied to the substrate through independent pathways.

[0021] This method may further include forming a silicon layer on the substrate before supplying the reducing gas.

[0022] The deposition of tungsten thin films can be achieved by replacing silicon atoms contained in the silicon matrix with tungsten atoms.

[0023] Impurities can be removed by generating plasma in the reaction space and stopping the supply of tungsten-containing gas to the substrate.

[0024] This method can further include blowing out the reaction space between depositing tungsten films and removing impurities.

[0025] The reaction space can be purged by not generating plasma in the reaction space.

[0026] The reducing gas may contain hydrogen, the tungsten-containing gas may contain tungsten hexafluoride gas, and the impurities may contain fluorine. Simple Explanation of the Diagram

[0027] The exemplary embodiments can be understood in more detail through the following description and related figures, in which: Figure 1 is a schematic diagram illustrating a substrate processing apparatus according to an exemplary embodiment. Figure 2 is a schematic diagram of a gas injection unit according to an exemplary embodiment. Figure 3 is an exploded view of the gas injection unit in Figure 2. Figure 4 is a diagram illustrating the state of plasma formation according to an exemplary embodiment. Figure 5 is a schematic flowchart illustrating a thin film formation method according to an exemplary embodiment. Figure 6 is a diagram illustrating the process cycle of a thin film formation method according to an exemplary embodiment. Figure 7 is a diagram used to explain the various processes used to form thin films in the process cycle. Implementation

[0028] The following will describe specific embodiments in detail with reference to the relevant drawings. However, the present invention may be embodied in different forms and should not be limited to the embodiments set forth herein. These embodiments are provided rather than intended to enable a thorough and complete understanding of the invention and to fully convey the scope of the invention to those skilled in the art.

[0029] It will also be understood that when a layer, film, region, or plate is referred to as being "on" another, it can be located directly on the other, or it can also have one or more intermediate layers, films, regions, or plates present.

[0030] Furthermore, spatial relative terms such as "above," "top," "below," or "bottom" are used here to conveniently describe a particular element depicted in the diagram or the characteristic relationship to one or more other elements or features. It will be understood that spatial relative terms are intended to cover different orientations of the device in use or operation other than those depicted in the diagram. In the diagram, the thickness of layers and regions is exaggerated for clarity. In the diagram, similar labels throughout refer to similar elements.

[0031] Figure 1 is a schematic diagram illustrating a substrate processing apparatus according to an exemplary embodiment. Figure 2 is a schematic diagram of a gas injection unit according to an exemplary embodiment, and Figure 3 is an exploded view of the gas injection unit in Figure 2. Figure 4 is a diagram illustrating the state of plasma formation according to an exemplary embodiment.

[0032] Referring to Figures 1 to 4, a substrate processing apparatus according to an exemplary embodiment is used for forming a thin film such as a tungsten thin film, and includes a cavity 10, a substrate support unit 20, a gas injection unit 30, and a gas supply unit 40. The substrate support unit 20 supports a substrate S located in the cavity 10. The gas injection unit 30 is located in the cavity facing the substrate support unit 20 and is used to inject process gas toward the substrate support unit 20. The gas supply unit 40 supplies gas to the gas injection unit 30. Furthermore, the substrate processing apparatus may further include an RF power supply 50 for applying power to generate plasma in the cavity 10 and a control unit (not shown) for controlling the RF power supply 50. Here, a first gas supply path for supplying a first gas and a second gas supply path for supplying a second gas are independently formed in the gas injection unit 30.

[0033] The cavity 10 provides a preset reaction space and maintains the seal of the preset reaction space. The cavity 10 may include a body 12 and a cover 14. The body 12 includes a flat portion having a roughly circular or rectangular shape and sidewalls extending upward from the flat portion to provide the preset reaction space. The cover 14 has a roughly circular or rectangular shape and is disposed on the body 12 to maintain the seal of the reaction space. However, the exemplary embodiments are not limited to the cavity 10. For example, the cavity 10 may have various shapes corresponding to the shape of the substrate S.

[0034] An exhaust port (not shown) can be defined in a predetermined area on the bottom surface of the cavity 10, and an exhaust pipe (not shown) connected to the exhaust port can be provided outside the cavity 10. Furthermore, the exhaust pipe can be connected to an exhaust device (not shown). For example, a vacuum pump, such as a turbomolecular pump, can be used as an exhaust device. Therefore, the interior of the cavity 10 can be evacuated by the exhaust device until a predetermined reducing pressure atmosphere (such as a predetermined pressure) is equal to or less than 0.1 mTorr. The exhaust pipe can be installed below the substrate support unit 20. Furthermore, the exhaust pipe can be installed on the side of the cavity 10 located below the substrate support unit 20 (the substrate support unit 20 will be described below). Furthermore, multiple exhaust pipes and exhaust devices for the exhaust pipes can be further installed to reduce exhaust time.

[0035] Furthermore, for the thin film formation process, the substrate S loaded into the cavity 10 can be located on the substrate support unit 20. Here, the substrate S can serve as a seed layer or nucleation layer for depositing a tungsten layer to form a tungsten thin film, or it can serve as a substrate on which a nucleation layer or seed layer has already been formed, so that a tungsten layer as the main layer can be formed. The substrate support unit 20 may include, for example, an electrostatic chuck to attract and hold the substrate S by electrostatic force, thereby setting and supporting the substrate S, or supporting the substrate S by vacuum attraction or mechanical force.

[0036] The substrate support unit 20 may have an external shape corresponding to the shape of the substrate S, such as circular or rectangular. The substrate support unit 20 may include a substrate support member 22 for mounting the substrate S and a lifter 24 disposed below the substrate support member 22 to elevate the substrate support member 22. Here, the size of the substrate support member 22 may be larger than the size of the substrate S. The lifter 24 may be provided to support at least one region (such as the central region) of the substrate support member 22 and is movable so that the substrate support member 22 is adjacent to the gas injection unit 30 when the substrate S is mounted. Furthermore, a heater (not shown) may be installed in the substrate support member 22. The heater can generate heat at a preset temperature to heat the substrate support member 22 and the substrate S located on the substrate support member 22, thereby causing a thin film to be uniformly deposited on the substrate S.

[0037] The gas supply unit 40 can be installed through the cover 14 of the cavity 10 and includes a first gas supplier 42 and a second gas supplier 44 that supply a first gas and a second gas to the gas injection unit 30, respectively. Here, the first gas may include a tungsten-containing gas, and the second gas may include a reducing gas. Conversely, 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 (WF6), and the reducing gas may include hydrogen (H2). Therefore, each of the first gas suppliers 42 and the second gas suppliers 44 does not need to supply only one gas. For example, each of the first gas suppliers 42 and the second gas suppliers 44 can be used to supply multiple gases simultaneously or to supply a gas selected from multiple gases.

[0038] The gas injection unit 30 is mounted in the cavity 10 (e.g., on the bottom surface of the cover 14), and a first gas supply path for injecting and supplying a first gas to the substrate and a second gas supply path for injecting and supplying a second gas to the substrate are formed in the gas injection unit 30. The first gas supply path and the second gas supply path can be independently separated from each other and independently supply the first gas and the second gas to the substrate so that the first gas and the second gas do not mix in the gas injection unit 30.

[0039] The gas injection unit 30 may include a top frame 32 and a base frame 34. The top frame 32 is detachably coupled to the bottom surface of the cover 14, with a portion of the top surface of the top frame 32 (such as the central portion of the top surface) and the bottom surface of the cover 14 separated by a predetermined distance. Therefore, the first gas supplied from the first gas supplier 42 can diffuse in the space between the top surface of the top frame 32 and the bottom surface of the cover 14. Furthermore, the base frame 34 is separated from the bottom surface of the top frame 32 by a predetermined distance. Therefore, the second gas supplied from the second gas supplier 44 can diffuse in the space between the bottom surface of the top frame 32 and the top surface of the base frame 34. The top frame 32 and the base frame 34 may be connected along their outer peripheral surfaces and form a separation space therein, thereby integrating them together. Alternatively, the outer peripheral surfaces of the top frame 32 and the base frame 34 may be sealed by separate seals.

[0040] A first gas supply path can be formed such that the first gas supplied from the first gas supplier 42 diffuses in the space between the bottom surface of the cover 14 and the top frame 32 and is supplied into the cavity 10 via the top frame 32 and the base frame 34. Similarly, a second gas supply path can be formed such that the second gas supplied from the second gas supplier 44 diffuses in the space between the bottom surface of the top frame 32 and the top surface of the base frame 34 and is supplied into the cavity 10 via the base frame 34. The first and second gas supply paths do not need to be interconnected; therefore, the first and second gases can be independently supplied from the gas supply unit 40 to the cavity via the gas injection unit 30.

[0041] The first electrode 38 can be mounted on the bottom surface of the base frame 34, and the second electrode 36 can be separated from the bottom side of the base frame 34 and the outer side of the first electrode 38 by a predetermined distance. Here, the base frame 34 and the second electrode 36 can be connected along the outer peripheral surfaces of the base frame 34 and the second electrode 36. Alternatively, the outer peripheral surfaces of the base frame 34 and the second electrode 36 can be sealed by a separate sealing element.

[0042] As described above, when the first electrode 38 and the second electrode 36 are installed, the first gas can be sprayed onto the substrate through the first electrode 38, and the second gas can be sprayed onto the substrate through the space between the first electrode 38 and the second electrode 36.

[0043] Radio frequency (RF) power can be applied from the RF power supply 50 to either the base 34 or the second electrode 36. Figure 4 illustrates an example of a structure where the base 34 is grounded and RF power is applied to the second electrode 36. When the base 34 is grounded, the first electrode 38 mounted on the bottom surface of the base 34 is also grounded. Therefore, when RF power is applied from the RF power supply 50 to the second electrode 36, a first excitation region (i.e., a first plasma region P1) can be formed between the gas jet unit 30 and the substrate support unit 20, and a second excitation region (i.e., a second plasma region P2) can be formed between the first electrode 38 and the second electrode 36.

[0044] Figure 4 is a diagram illustrating the state of plasma formation according to an exemplary embodiment. Although Figure 4 uses the first electrode 38 and the substrate support unit 20 as grounded, and radio frequency power is applied from the radio frequency power supply 50 to the second electrode 36 as an example, the structure of applying power from the power supply is not limited to this.

[0045] As shown in Figure 4, a first gas (such as a tungsten-containing gas) can be supplied into the cavity 10 along the arrow indicated by the solid line, and a second gas (such as a reducing gas) can be supplied into the cavity 10 along the arrow indicated by the dashed line. The first gas can pass through the interior of the first electrode 38 and be supplied into the cavity 10, and the second gas can pass through the space between the first electrode 38 and the second electrode 36 and be supplied into the cavity 10. The first gas can pass through the first electrode 38 and be supplied into the cavity 10.

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

[0047] Therefore, when the first gas is supplied through the first electrode 38, it is excited in the first plasma region P1 formed outside the gas injection unit 30. Furthermore, when the second gas is supplied through the space between the first electrode 38 and the second electrode 36, it is excited in the region between them, corresponding 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. Thus, the substrate processing apparatus according to an exemplary embodiment can excite the first gas and the second gas in multiple plasma regions of different sizes. And because the first gas and the second gas are excited in multiple plasma regions of different sizes, each gas can be distributed through an optimized supply path for thin film deposition.

[0048] Hereinafter, a thin film forming method according to an exemplary embodiment will be described in detail with reference to FIGS. 5 to 7. In describing the thin film forming method according to an exemplary embodiment, descriptions that are repeated in the above description of the substrate processing apparatus will be omitted.

[0049] Figure 5 is a schematic flowchart illustrating a thin film forming method according to an exemplary embodiment, Figure 6 is a diagram for explaining the process cycle of the thin film forming method according to an exemplary embodiment, and Figure 7 is a diagram for explaining the various processes for forming a thin film in the process cycle.

[0050] Please refer to Figures 5 to 7. A thin film formation method according to an exemplary embodiment includes: a process S100 of supplying a reducing gas to a substrate S located in a reaction space, a process S200 of applying a power source to generate plasma in the reaction space, and a process S300 of supplying a tungsten-containing gas to the substrate S, wherein the process S300 of supplying the tungsten-containing gas to the substrate S is performed intermittently while the reducing gas is being supplied.

[0051] The process S100 of supplying reducing gas supplies reducing gas to the substrate S located in the reaction space of the cavity 10. The process S100 of supplying reducing gas sustains the supply of reducing gas until the tungsten thin film is formed in the thin film formation method according to an exemplary embodiment. Here, the reducing gas may include a hydrogen (H)-containing gas, such as hydrogen (H2).

[0052] The process S100 for supplying reducing gas can supply reducing gas to the substrate S before the tungsten-containing gas is supplied, and the supply of reducing gas is continuously maintained until a tungsten thin film is formed. Here, the reaction space in the cavity 10 can be formed into a reducing atmosphere by a reducing gas (such as hydrogen (H2)) before the tungsten-containing gas (such as tungsten hexafluoride gas (WF6)) is supplied. As described above, when the reducing atmosphere is formed in the reaction space of the cavity 10 by hydrogen (H2) before the tungsten hexafluoride gas (WF6) is supplied, the fluorine (F) component of the tungsten hexafluoride gas (WF6) is mainly removed because the tungsten hexafluoride gas (WF6) reacts with the hydrogen (H) radicals excited by hydrogen (H2) or the plasma in the space between the gas injection unit 30 and the substrate S.

[0053] Furthermore, as described above, the substrate S can be a substrate that serves as a seed layer or nucleation layer for forming a tungsten thin film, or it can be a substrate on which a nucleation layer or seed layer has already been formed to form a tungsten layer as the main layer.

[0054] In the process S200 of applying power, a high-frequency power supply is applied from the radio frequency power supply 50 to generate plasma in the reaction space. When hydrogen (H2) is supplied as the reducing gas in the process S100 of supplying reducing gas, hydrogen (H2) can be excited into hydrogen (H) radicals by the plasma generated in the reaction space in the process S200 of applying power.

[0055] The process S300, which supplies tungsten-containing gas, supplies the tungsten-containing gas to the substrate S. Here, the tungsten-containing gas may include a gas containing tungsten (W), such as tungsten hexafluoride gas (WF6).

[0056] Therefore, when a high-frequency power supply is applied from the RF power supply 50 during the power application process and tungsten-containing gas is supplied to the substrate S in the tungsten-containing gas supply process S300, tungsten (W) deposition defects are generally generated in the gas injection unit 30. That is, when a high-frequency power supply is applied to a typical shower head type gas injection unit 30 and the first gas (i.e., tungsten-containing gas) and the second gas (i.e., reducing gas) are supplied through the gas injection unit 30, tungsten (W) may be deposited in the gas injection unit 30 because the tungsten-containing gas and the reducing gas react with each other in the gas injection unit 30.

[0057] However, as described above, according to an exemplary embodiment, the first gas supply path and the second gas supply path are formed independently and separately in the gas injection unit 30 rather than being connected to each other. Therefore, because the tungsten-containing gas supplied through the first electrode 38 in FIG. 4 reacts with the reducing gas located below the gas injection unit 30 rather than with the reducing gas supplied between the first electrode and the second electrode 36 in the gas injection unit 30, tungsten (W) deposition in the gas injection unit 30 can be effectively prevented.

[0058] As described above, when the process S300 of supplying tungsten-containing gas is carried out and the process S100 of supplying reducing gas is continued, tungsten hexafluoride gas (WF6) will be reduced by reacting with hydrogen (H2) as shown in the following chemical reaction formula 1, and a tungsten layer will be formed on the substrate S.

[0059] [Chemical Reaction Formula 1]

[0060] Therefore, the process S300 of supplying tungsten-containing gas can be carried out intermittently while the reducing gas is being supplied. That is, the process S100 of supplying reducing gas will continue until the tungsten film is formed, and the process S300 of supplying tungsten-containing gas can be carried out intermittently so that the supply and cessation of tungsten-containing gas are alternately carried out while the reducing gas is being supplied.

[0061] In this process, during the portion where hydrogen-containing gas (i.e., hydrogen (H2)) and tungsten-containing gas (i.e., tungsten hexafluoride gas (WF6)) are simultaneously supplied to the substrate S, the tungsten hexafluoride gas (WF6) and hydrogen (H2) react with each other, and a tungsten thin film is deposited on the substrate S. In other words, when tungsten hexafluoride gas (WF6) and hydrogen (H2) react with each other during the portion where tungsten hexafluoride gas (WF6) and hydrogen (H2) are simultaneously supplied, a process for depositing a tungsten layer on the substrate S can be performed.

[0062] When only hydrogen (H2) is supplied to the substrate S because the tungsten-containing gas supply is stopped, impurities formed on the substrate S, such as fluorine (F) components, can be removed by the supplied hydrogen (H2).

[0063] Even when tungsten hexafluoride gas (WF6) and hydrogen (H2) are supplied simultaneously and react with each other, the fluorine (F) component contained in the tungsten hexafluoride gas (WF6) is not completely removed. Therefore, in the thin film formation method according to an exemplary embodiment, since the supply and cessation of the tungsten hexafluoride gas (WF6) are repeated while the hydrogen (H2) is being supplied, the tungsten layer will be deposited in the portion where both tungsten hexafluoride gas (WF6) and hydrogen (H2) are supplied simultaneously, and the deposited tungsten layer will be treated with hydrogen (H2) to remove impurities (i.e., fluorine (F) components) contained in the deposited tungsten layer in the portion where only hydrogen (H2) is supplied. As described above, in an exemplary embodiment, by alternating between the process of depositing a tungsten layer and the process of removing impurities from the deposited tungsten layer, the fluorine (F) content in the tungsten layer can be reduced to a level of low fluorine tungsten (LWF) where the fluorine (F) content in the tungsten layer cannot be detected by component analysis.

[0064] According to an exemplary embodiment, the thin film formation method may further include a process of supplying a silicon-containing gas to a substrate S before supplying a reducing gas. That is, a silicon layer may be formed on the substrate S before the reducing gas is supplied, and then a tungsten thin film may be deposited on the substrate S in a process S300 where tungsten gas is supplied by replacing silicon atoms contained in the silicon layer with tungsten atoms. Here, the silicon-containing gas may include silane (SiH4) gas, and the silicon atoms contained in the silicon layer may react with the tungsten-containing gas and be replaced by tungsten atoms as shown in the following chemical reaction formula 2.

[0065] [Chemical Reaction Equation 2]

[0066]

[0067] Therefore, the process of supplying silicon-containing gas can be completed before the process of supplying reducing gas S100. Furthermore, the process of supplying silicon-containing gas can be performed once before a process cycle including the process of supplying reducing gas to the substrate S located in the reaction space, the process of applying power to generate plasma in the reaction space S200, and the process of supplying tungsten-containing gas to the substrate S300, or can be repeated before the process of supplying reducing gas included in the process cycle, as will be described below.

[0068] Therefore, when hydrogen (H2) is supplied to excite hydrogen (H) radicals by plasma and reacts with tungsten hexafluoride gas (WF6) in the part where hydrogen (H2) and tungsten hexafluoride gas (WF6) are supplied simultaneously, and when the tungsten layer deposited on the substrate S is treated by using hydrogen in the part where only hydrogen (H2) is supplied to excite hydrogen (H2) radicals by plasma to hydrogen (H) radicals, the process S200 of applying power can be carried out continuously.

[0069] However, when reducing gas is supplied, the process S200 of applying power can be performed intermittently, and when power is applied to generate plasma in the reaction space, the process of supplying tungsten-containing gas can be performed. Therefore, the exemplary embodiment may further include a process of purging the reaction space while applying power.

[0070] When tungsten hexafluoride (WF6) gas is supplied intermittently, it remains in the reaction space even immediately after the supply stops. In this case, when the WF6 supply stops and hydrogen (H2) is supplied, the supplied hydrogen (H2) may react with the remaining WF6, potentially resulting in insufficient treatment of the tungsten layer deposited on the substrate S.

[0071] Therefore, in an exemplary embodiment, the process S200 of applying power can be performed intermittently while the reducing gas is being supplied, and the reaction gas can be purged to remove the tungsten hexafluoride gas (WF6) remaining in the reaction space in the cavity 10 when no power is applied.

[0072] After the power supply is stopped and the reaction space is purged, process S200, which applies power, can begin before the tungsten-containing gas is supplied again. Here, only hydrogen (H2) is supplied before power is applied, and the tungsten-containing gas is supplied again. The supplied hydrogen (H2) is excited by plasma to process the tungsten layer deposited on the substrate S, thereby removing the fluorine (F) component contained in the tungsten layer. Furthermore, process S200, which applies power, can be completed simultaneously with the tungsten-containing gas supply stopping, ensuring sufficient time to purge the reaction space.

[0073] Furthermore, the process S100 for supplying reducing gas can supply reducing gas to the substrate S before supplying tungsten-containing gas and continuously maintain the supply of reducing gas until a tungsten thin film is formed. Here, the reaction space in the cavity 10 can be formed into a reducing atmosphere by the reducing gas supplied before the tungsten-containing gas is supplied. Next, since tungsten hexafluoride gas (WF6) is supplied as tungsten-containing gas, the hydrogen (H) component of the reducing gas continuously supplied to the reaction space and the fluorine (F) component of the tungsten hexafluoride gas (WF6) will couple, generating and removing hydrogen fluoride (HF) gas, and a tungsten layer with most of the fluorine (F) component removed can be formed on the substrate S.

[0074] As shown in Figures 6 and 7, in an exemplary embodiment, a process cycle is formed by a portion (part ①) where a tungsten layer is deposited while hydrogen (H2) is supplied, a power source is applied, and tungsten hexafluoride gas (WF6) is supplied, and a portion (part ②) where impurities are removed while hydrogen (H2) is supplied, a power source is applied, but tungsten hexafluoride gas (WF6) is not supplied. Alternatively, a process cycle may further include a portion for purging the reaction space between the portion for depositing the tungsten layer (part ①) and the portion for removing impurities (part ②). The process cycle can be repeated multiple times, and in this way, the portions for depositing the tungsten layer, purging the reaction space, and removing impurities can be repeatedly included to effectively remove the fluorine (F) component contained in the tungsten layer, thereby forming a tungsten film with a significantly reduced impurity concentration.

[0075] In a thin film formation method according to an exemplary embodiment, a tungsten thin film with reduced film stress and reduced impurity concentration can be formed by alternately repeating the process of depositing a tungsten layer and the process of removing impurities contained in the tungsten layer.

[0076] Furthermore, the efficiency of the impurity removal process can be improved by blowing away the reactive gas before removing the impurities contained in the tungsten layer, thereby reducing the fluorine content in the tungsten layer to a level of low-fluorine tungsten where the fluorine content cannot be detected by component analysis.

[0077] While exemplary embodiments of the invention have been described, it should be understood that the invention is not limited to these embodiments, and those skilled in the art can make various changes and modifications within the scope and spirit of the invention as claimed below. Therefore, it should be understood that simple modifications to embodiments of the invention may fall within the technical spirit of the invention.

[0078] 10: Cavity 12:Ontology 14: Cover 20: Substrate support unit 22: Substrate support 24: Lifter 30: Gas injection unit 32: Top Frame 34: Base frame 36: Second electrode 38: First electrode 40: Gas supply unit 42: First gas supply unit 44: Second gas supply unit 50: Radio Frequency Power Supply S:Substrate P1: First Plasma Region P2: Second Plasma Region S100, S200, S300: Manufacturing Process ①, ②: Parts

Claims

1. A method of forming a thin film, comprising: supplying a reducing gas to a substrate located in a reaction space; applying a power source to generate plasma in the reaction space; and supplying a tungsten-containing gas to the substrate, wherein the supply of the tungsten-containing gas is performed intermittently while the reducing gas is being supplied, and wherein the supply of the reducing gas is performed before the tungsten-containing gas is supplied and is continued until a tungsten thin film is formed.

2. The method as described in claim 1, wherein the reducing gas and the tungsten-containing gas are supplied to the substrate through independent paths.

3. The method as claimed in claim 1, wherein the application of the power source is performed intermittently while the reducing gas is supplied, and the supply of the tungsten-containing gas is performed while the power source is applied to generate plasma in the reaction space.

4. The method as described in claim 3, wherein the application of the power source begins before the supply of the tungsten-containing gas.

5. The method as described in claim 1 further includes supplying a silicon-containing gas to the substrate before supplying the reducing gas.

6. The method as described in claim 5, wherein the supply of the silicon-containing gas is completed before the supply of the reducing gas.

7. The method as described in claim 3, wherein the application of the power source is completed when the supply of the tungsten-containing gas is finished.

8. The method as described in claim 3 further includes blowing out the reaction space when no power source is applied.

9. A method of forming a thin film, comprising: supplying a reducing gas to a substrate located in a reaction space; depositing a tungsten thin film on the substrate by supplying a tungsten-containing gas; and removing a plurality of impurities remaining on the tungsten thin film, wherein the deposition of the tungsten thin film and the removal of the impurities are performed alternately while the reducing gas is supplied, and wherein the supply of the reducing gas is performed before the tungsten-containing gas is supplied and is continued until the tungsten thin film is formed.

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

11. The method as described in claim 10, wherein the reducing gas and the tungsten-containing gas are supplied to the substrate through independent paths.

12. The method as described in claim 9 further comprises: forming a silicon layer on the substrate prior to supplying the reducing gas.

13. The method as described in claim 12, wherein the deposition of the tungsten thin film is performed by replacing silicon atoms contained in the silicon mass with tungsten atoms.

14. The method of claim 10, wherein the removal of the impurities is carried out by generating plasma in the reaction space and stopping the supply of the tungsten-containing gas to the substrate.

15. The method as described in claim 10 further comprises: blowing out the reaction space between depositing the tungsten film and removing the impurities.

16. The method as described in claim 15, wherein the purging of the reaction space is carried out in a manner in which no plasma is generated in the reaction space.

17. The method as described in claim 10, wherein the reducing gas comprises hydrogen, the tungsten-containing gas comprises tungsten hexafluoride gas, and the impurities comprise fluorine.

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