Film deposition method and film deposition apparatus

Abstract

To improve the barrier properties at the interface between the substrate and the graphene film. [Solution] The film formation method includes a loading step, a first step, and a second step. The loading step involves loading the substrate into the processing container. The first step involves forming an amorphous or microcrystalline interface layer on the substrate using a plasma of a first mixed gas containing a carbon-containing gas. The second step involves forming a graphene film on the interface layer using a plasma of a second mixed gas containing a carbon-containing gas.

Description

Technical Field

[0001] The present disclosure relates to a film forming method and a film forming apparatus.

Background Art

[0002] In recent years, graphene films have attracted attention as new thin film barrier layer materials to replace metal nitride films, and various technologies have been proposed as graphene film forming technologies. For example, it has been proposed to directly form a graphene film on a silicon substrate, an insulating film, etc. by performing graphene film formation at a high radical density and a low electron temperature using a microwave plasma CVD (Chemical Vapor Deposition) apparatus (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present disclosure provides a technique capable of improving the barrier property at the interface between a substrate and a graphene film.

Means for Solving the Problems

[0005] The film forming method according to one aspect of the present disclosure includes a loading step, a first step, and a second step. The loading step loads a substrate into a processing container. The first step forms an interface layer having an amorphous structure or a microcrystalline structure on the substrate by plasma of a first mixed gas containing a carbon-containing gas. The second step forms a graphene film on the interface layer by plasma of a second mixed gas containing a carbon-containing gas.

Effects of the Invention

[0006] According to this disclosure, the barrier properties at the interface between the substrate and the graphene film can be improved. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 is a flowchart showing an example of the flow of a film deposition method according to one embodiment. [Figure 2] Figure 2 shows an example of the state transition of a substrate from the formation of an amorphous or microcrystalline interface layer to the formation of a graphene film in one embodiment. [Figure 3] Figure 3 shows an example of the mechanism in the state transition of a substrate from the formation of an amorphous or microcrystalline interface layer to the formation of a graphene film. [Figure 4] Figure 4 shows an example of the relationship between the flow rate control pattern of H2 gas and the composition ratios of SiC and SiO in an interface layer having an amorphous or microcrystalline structure. [Figure 5] Figure 5 shows an example of the structure of the sample used for evaluation. [Figure 6] Figure 6 shows an example of the analysis results obtained by SIMS analysis of the surface of a sample. [Figure 7] Figure 7 shows an example of the analysis results obtained by SIMS analysis of the surface of a sample. [Figure 8A] Figure 8A shows an example of analysis results obtained by XPS analysis of a heat-treated (annealed) substrate. [Figure 8B] Figure 8B shows an example of analysis results obtained by XPS analysis of a heat-treated (annealed) substrate. [Figure 8C] Figure 8C shows an example of analysis results obtained by XPS analysis of a heat-treated (annealed) substrate. [Figure 9] Figure 9 is a schematic cross-sectional view showing an example of a film deposition apparatus according to one embodiment. [Modes for carrying out the invention]

[0008] Various embodiments will be described in detail below with reference to the drawings. However, the disclosed technology is not limited to the embodiments described below.

[0009] Incidentally, when a graphene film is formed directly on a silicon substrate or insulating film, grain boundaries are generated in the resulting graphene film. The generation of grain boundaries in the graphene film can reduce the barrier properties at the interface between the silicon substrate and the graphene film. In other words, the grain boundaries of the graphene film become diffusion paths, allowing elements to diffuse from the silicon substrate or from a metal-containing film formed on the graphene film to the silicon substrate.

[0010] Therefore, it is expected that this will improve the barrier properties at the interface between the substrate and the graphene film.

[0011] [An example of the flow of a film deposition method according to one embodiment] Figure 1 is a flowchart showing an example of the flow of a film deposition method according to one embodiment.

[0012] First, the substrate is brought into the processing container and placed on a mounting platform located inside the processing container (step S101, loading process).

[0013] Next, an amorphous or microcrystalline interface layer (hereinafter sometimes referred to as the interface amorphous layer) is formed on the substrate by a plasma of a first mixed gas containing a carbon-containing gas (Step S102, interface amorphous layer formation step). Examples of carbon-containing gases include acetylene (C2H2), ethylene (C2H4), methane (CH4), ethane (C2H6), propane (C3H8), propylene (C3H6), methanol (CH3OH), ethanol (C2H5OH), etc. In addition to the carbon-containing gas, the first mixed gas also contains a hydrogen-containing gas and an inert gas. Examples of hydrogen-containing gases include H2 gas and NH3 gas. Examples of inert gases include Ar gas, N2 gas, and He gas. The plasma of the first mixed gas is generated, for example, using microwaves. In the interfacial amorphous layer formation step, the flow rate of the hydrogen-containing gas in the first mixed gas may be controlled to different flow rates over time. The interfacial amorphous layer formation step is an example of the first step.

[0014] Next, a graphene film is formed on the interfacial amorphous layer by the plasma of the second mixed gas containing a carbon-containing gas (step S103, graphene film forming step). As the carbon-containing gas, the same gas as the carbon-containing gas contained in the first mixed gas can be used. In addition, the second mixed gas contains a hydrogen-containing gas and an inert gas in addition to the carbon-containing gas. As the hydrogen-containing gas, the same gas as the hydrogen-containing gas contained in the first mixed gas can be used. As the inert gas, the same gas as the inert gas contained in the first mixed gas can be used. Further, the plasma of the second mixed gas is generated using, for example, microwaves. In the graphene film forming step, the flow rate of the hydrogen-containing gas in the second mixed gas is maintained at a constant value. In this case, the flow rate of the hydrogen-containing gas in the second mixed gas is preferably not less than the flow rate of the hydrogen-containing gas in the first mixed gas. The hydrogen-containing gas contributes as an etchant for the graphene film when forming the graphene film. Therefore, by increasing the flow rate of the hydrogen-containing gas in the second mixed gas, unstable carbon bonds can be removed from the graphene film, so that the structure of the graphene film can be stabilized. The graphene film forming step is an example of the second step.

[0015] When the formation of the graphene film is completed, the substrate is carried out of the processing chamber using a conveyance mechanism (not shown) (step S104).

[0016] When the substrate is carried out of the processing chamber, the inside of the processing chamber is cleaned (step S105). For example, a dummy wafer is placed on the mounting table and a cleaning gas is supplied into the processing chamber to remove carbon films such as amorphous carbon films adhering to the inner wall of the processing chamber. As the cleaning gas, O2 gas can be used, but a gas containing oxygen such as CO gas or CO2 gas may also be used. Further, the cleaning gas may contain a noble gas such as Ar gas. Also, the dummy wafer may not be provided. Further, the cleaning may be performed for each film forming process, or may be performed when a predetermined number of film forming processes has been reached. When the cleaning is completed, the process ends.

[0017] Thus, by forming a graphene film after forming an interface layer having an amorphous structure or a microcrystalline structure on a substrate, the grain boundaries of the graphene film can be blocked by the interface layer having an amorphous structure or a microcrystalline structure without grain boundaries. As a result, the barrier property at the interface between the substrate and the graphene film can be improved.

[0018] [State transition until formation of graphene film] Next, with reference to FIG. 2, the state transition of the substrate from the formation of the interface layer having an amorphous structure or a microcrystalline structure to the formation of the graphene film will be described. The interface layer will be described as an interface amorphous layer having an amorphous structure and may be collectively referred to hereinafter. FIG. 2 is a diagram showing an example of the state transition of the substrate from the formation of the interface amorphous layer to the formation of the graphene film in one embodiment. In FIG. 2, the state transition when the interface amorphous layer forming step and the graphene film forming step are performed on the substrate W on which the underlayer film 15 is formed is schematically shown. State 21 is a state in which the substrate W is carried into the processing chamber, and a natural oxide film (an example of an oxygen-containing layer) 17 is formed on the surface of the underlayer film 15. The underlayer film 15 is, for example, a polysilicon (polycrystalline silicon) film or a silicon film, and the natural oxide film 17 is, for example, a silicon oxide film (SiO2). The natural oxide film 17 is formed, for example, by oxidizing the surface of the underlayer film 15 with oxygen derived from oxygen, moisture, etc. in the transfer device, the processing chamber, etc.

[0019] When the interfacial amorphous layer formation process is performed on the substrate W in state 21, the substrate W transitions to state 22. In the interfacial amorphous layer formation process, the active carbon species contained in the plasma of the first mixed gas react with the native oxide film 17 on the underlayment 15, thereby forming an interfacial amorphous layer 18 on the silicon underlayment 15, as shown in state 22. The interfacial amorphous layer 18 is a layer containing at least one of silicon carbide (SiC) and carbon-containing silicon oxide (SiOC). In state 22, when the carbon concentration in the native oxide film 17 increases to a predetermined value and becomes saturated, the reaction between the active carbon species and the native oxide film 17 stops, and the formation of the interfacial amorphous layer 18 is completed.

[0020] Once the formation of the interface amorphous layer 18 is complete, a graphene film formation process is performed on the substrate W in state 22. As the graphene film formation progresses, the substrate W transitions to state 23. In state 23, a graphene film 19 is formed on the interface amorphous layer 18. That is, a state can be achieved in which the interface amorphous layer 18, which does not have grain boundaries, is located between the underlayer film 15 and the graphene film 19.

[0021] The presence of an amorphous interface layer 18 between the undercoat 15 and the graphene film 19 improves the barrier properties at the interface between the substrate W and the graphene film 19 compared to the case where the graphene film is directly formed on a silicon substrate or insulating film. In other words, when a graphene film is directly formed on a silicon substrate or insulating film, the grain boundaries of the graphene film become diffusion paths, allowing elements to diffuse from the silicon substrate or from a metal-containing film formed on the graphene film to the silicon substrate. In contrast, in the film formation method according to one embodiment, by forming an amorphous interface layer 18 between the undercoat 15 and the graphene film 19, the grain boundaries that serve as diffusion paths for the graphene film 19 are blocked by an amorphous interface layer that does not have grain boundaries. As a result, the diffusion of elements through the diffusion paths of the graphene film 19 is suppressed, and the barrier properties at the interface between the substrate W and the graphene film 19 can be improved.

[0022] In the above explanation, the case in which the interface amorphous layer formation process and the graphene film formation process are performed on a substrate W on which the undercoat 15 has been formed has been described. However, the substrate W to be film-formed may also be a silicon substrate 16 that does not have the undercoat 15. In this case as well, in state 21, a native oxide film 17 is formed on the surface of the silicon substrate 16. When the interface amorphous layer formation process is performed on the substrate W in state 21, the substrate W transitions to state 22. In the interface amorphous layer formation process, the active species of carbon contained in the plasma of the first mixed gas react with the native oxide film 17 on the silicon substrate 16, so that an interface amorphous layer 18 is formed on the silicon substrate 16 as shown in state 22. Once the formation of the interface amorphous layer 18 is complete, the graphene film formation process is performed on the substrate W in state 22, and as the graphene film formation progresses, the substrate W transitions to state 23.

[0023] [Mechanisms in the state transitions leading to the formation of graphene films] Next, using Figure 3, the mechanism of the substrate state transition from the formation of the interfacial amorphous layer 18 to the formation of the graphene film 19 will be explained. Figure 3 is a diagram showing an example of the mechanism of the substrate state transition from the formation of the interfacial amorphous layer 18 to the formation of the graphene film 19. State 21a shown in Figure 3 corresponds to state 21 in Figure 2, state 22a corresponds to state 22 in Figure 2, and state 23a corresponds to state 23 in Figure 2. As shown in state 21a, when active species of carbon (C), hydrogen (H), and argon (Ar) are supplied to the surface of the native oxide film 17, the following reactions of equations (1) to (4) occur in the native oxide film 17 and on the surface of the undercoat film 15.

[0024] 2H+O → H2O↑ ···(1) C+O → CO↑ ···(2) C+4H → CH4↑ ···(3) SiO+2C → SiC+CO↑ ···(4)

[0025] In other words, oxygen is removed from the surface of the native oxide film 17 by the reactions of equations (1) and (2). Subsequently, as the oxygen on the surface of the native oxide film 17 decreases, the reaction of equation (4) occurs in the native oxide film 17 and on the surface of the underlayer film 15, as shown in state 22a, thereby forming Si-C bonds. When the reaction of equation (4) reaches saturation, the formation of the interfacial amorphous layer 18 is completed.

[0026] Once the formation of the interface amorphous layer 18 is complete, a graphene film 19 is formed on the surface of the interface amorphous layer 18 by carbon atoms bonding together, as shown in state 23a.

[0027] [Compositional changes of the interfacial amorphous layer in response to H2 gas flow rate control] Next, using Figure 4, we will explain the compositional changes of the interface amorphous layer 18 in response to the flow rate control of the hydrogen-containing gas (H2 gas). Figure 4 is a diagram showing an example of the relationship between the flow rate control pattern of H2 gas and the respective composition ratios of SiC and SiO in the interface amorphous layer 18. In Figure 4, the horizontal axis shows four flow rate control patterns that control the flow rate of H2 gas in the first mixed gas from 0 sccm to 33 sccm over time. The four flow rate control patterns are patterns (1) to (4) below. Pattern (1): A pattern where the H2 gas flow rate is set to 0 sccm for 0 seconds, and then set to 33 sccm for 70 seconds (expressed as "0>70s"). Pattern (2): A pattern where the H2 gas flow rate is set to 0 sccm for 5 seconds, and then set to 33 sccm for 60 seconds (expressed as "5>60s"). Pattern (3): A pattern where the H2 gas flow rate is set to 0 sccm for 20 seconds, and then to 33 sccm for 50 seconds (expressed as "20>50s"). Pattern (4): The pattern involves setting the H2 gas flow rate to 0 sccm for 60 seconds, and then setting it to 33 sccm for 0 seconds (expressed as "60>0s").

[0028] Furthermore, in Figure 4, the vertical axis shows the composition ratios of SiC and SiO in the interface amorphous layer 18. The composition ratios of SiC and SiO were calculated using the analysis results obtained by TEM (Transmission Electron Microscope)-EELS (Electron Energy-Loss Spectroscopy) analysis of the interface amorphous layer 18.

[0029] As shown in Figure 4, as the time spent setting the H2 gas flow rate in the first mixed gas to 0 sccm increases, the composition ratio of SiC in the interface amorphous layer 18 decreases while the composition ratio of SiO increases. On the other hand, as the time spent setting the H2 gas flow rate in the first mixed gas to 0 sccm decreases, the composition ratio of SiC in the interface amorphous layer 18 increases while the composition ratio of SiO decreases.

[0030] As shown in Figure 4, when the flow rate of H2 gas in the first mixed gas is controlled from a first flow rate (0 sccm) to a second flow rate (33 sccm), which is greater than the first flow rate, over time, the composition ratios of SiC and SiO in the interface amorphous layer 18 change. In other words, in the interface amorphous layer formation process, by controlling the flow rate of the hydrogen-containing gas in the first mixed gas to different flow rates over time, the composition of the formed interface amorphous layer 18 can be changed according to the flow rate of the hydrogen-containing gas. For example, in the interface amorphous layer formation process, when controlling the flow rate of the hydrogen-containing gas in the first mixed gas from a first flow rate to a second flow rate, the composition ratio of SiC in the interface amorphous layer 18 can be increased by reducing the setting time of the first flow rate. As a result, a bonding force due to Si-C bonds is imparted to the interface amorphous layer 18 located between the base film 15 and the graphene film 19, thereby improving the adhesion between the base film 15 and the graphene film 19. On the other hand, in the interfacial amorphous layer formation process, the composition ratio of SiC in the interfacial amorphous layer 18 can be reduced by decreasing the setting time of the first flow rate. As a result, the electrical resistance value of the interfacial amorphous layer 18 located between the base film 15 and the graphene film 19 changes, and the contact resistance characteristics between the base film 15 and the graphene film 19 can be appropriately adjusted.

[0031] [Evaluation of barrier properties] Next, the evaluation of the barrier properties of a graphene film formed on a substrate by the film deposition method according to the embodiment will be explained using Figures 5 to 7. The inventors formed a graphene film on a sample by the film deposition method according to the embodiment and investigated the barrier properties at the interface between the formed graphene film and the sample. Figure 5 shows an example of the structure of sample 30 used for evaluation. Sample 30 has a phosphorus (P)-doped polysilicon film 32 as an underlayer on a silicon substrate 31. Figure 5 shows a state in which an interface amorphous layer 33 and a graphene film 34 are formed on the phosphorus-doped polysilicon film 32 in this order from bottom to top. A tungsten (W) film 35 is further formed on the graphene film 34 as a metal-containing film. For the evaluation of barrier properties, sample 30 shown in Figure 5 was heated at 800°C for 2 hours in an N2 / H2 gas atmosphere, and then the surface of sample 30 was analyzed by SIMS (Secondary Ion Mass Spectrometry).

[0032] Figures 6 and 7 show examples of analysis results obtained by SIMS analysis of the surface of sample 30. In Figures 6 and 7, the horizontal axis represents the depth [mm] from the surface of sample 30. In Figure 6, the vertical axis represents the atomic concentration of phosphorus (P) [atoms / cm3], and in Figure 7, the vertical axis represents the atomic concentration of silicon (Si) [atoms / cm3]. Note that Figures 6 and 7 show the analysis results for two samples of sample 30.

[0033] The analysis results in Figures 6 and 7 show that the presence of an amorphous interfacial layer 33 between the phosphorus-doped polysilicon film 32 and the graphene film 34 prevents the diffusion of phosphorus and silicon from the phosphorus-doped polysilicon film 32 into the tungsten film 35. In other words, the analysis results in Figures 6 and 7 show that by forming the graphene film 34 using the film formation method according to the embodiment, the barrier properties at the interface between the phosphorus-doped polysilicon film 32, which is the underlying film on the substrate, and the graphene film 34 can be improved.

[0034] [Evaluation of adhesion] Furthermore, the inventors evaluated the adhesion between the phosphorus-doped polysilicon film 32, which is the underlayer on the substrate, and the graphene film 34 using the sample 30 shown in Figure 5. In the adhesion evaluation, the presence or absence of delamination between the phosphorus-doped polysilicon film 32 and the graphene film 34 was examined for the sample 30 shown in Figure 5 in accordance with JIS K5400-8.5 (JIS D0202) "Adhesion - Check Test". As a result, no delamination between the phosphorus-doped polysilicon film 32 and the graphene film 34 occurred. From this evaluation result, it can be seen that by forming the graphene film 34 using the film formation method according to the embodiment, adhesion between the phosphorus-doped polysilicon film 32, which is the underlayer on the substrate, and the graphene film 34 can be obtained.

[0035] [Differentiation] Although one embodiment has been described so far, the embodiment can be further modified.

[0036] In the above embodiment, a third step may be performed between the loading step (step S101) and the interface amorphous formation step (step S102) to modify the native oxide film on the substrate or silicon substrate using a plasma of a third mixed gas containing a hydrogen-containing gas. For example, H2 gas can be used as the hydrogen-containing gas. In addition, the third mixed gas may contain an inert gas in addition to the hydrogen-containing gas. For example, Ar gas can be used as the inert gas. In the third step, the native oxide film on the substrate or silicon substrate can be modified into a film with more oxygen vacancies than the native oxide film (hereinafter referred to as the "modified oxide film"). As a result, in the interface amorphous layer formation step, the active species of carbon can be used to fill the oxygen vacancies in the modified oxide film, and as a result, the film deposition rate of the interface amorphous layer can be increased.

[0037] Furthermore, in the above embodiment, a fourth step may be performed between the interface amorphous formation step (step S102) and the graphene film formation step (step S103) to modify the surface layer of the interface amorphous layer using a plasma of a third mixed gas containing a hydrogen-containing gas. For example, H2 gas can be used as the hydrogen-containing gas. In addition, the third mixed gas may contain an inert gas in addition to the hydrogen-containing gas. For example, Ar gas can be used as the inert gas. In the fourth step, the surface layer of the interface amorphous layer can be modified into a layer with more oxygen vacancies (hereinafter referred to as the "modified layer"). As a result, in the graphene film formation step, the active species of carbon can be used to fill the oxygen vacancies in the modified layer, and as a result, the graphene film deposition rate can be increased.

[0038] Furthermore, in the above embodiment, a fifth step may be performed between the loading step (step S101) and the interface amorphous formation step (step S102) to etch the native oxide film on the underlayment or on the silicon substrate. In the fifth step, for example, a portion of the native oxide film is removed by a plasma of a fourth mixed gas containing a carbon-containing gas, a hydrogen-containing gas, and an inert gas. This allows the active species of carbon to react with the thin native oxide film in the interface amorphous formation step, and as a result, the deposition rate of the interface amorphous layer can be increased.

[0039] Furthermore, a sixth step may be performed between the fifth step and the interface amorphous formation step (step S102), in which an oxygen-containing gas is supplied into the processing container. In the sixth step, after the removal of the native oxide film, a pseudo-native oxide film with more oxygen vacancies than the native oxide film can be formed. This allows the reactive carbon species to fill the oxygen vacancies in the pseudo-native oxide film during the interface amorphous layer formation step, thereby increasing the deposition rate of the interface amorphous layer.

[0040] Furthermore, in the above embodiment, a seventh step may be performed before the loading process (step S101) in which oxygen in the processing container is removed by a hydrogen-containing gas plasma while no substrate is present in the processing container. This makes it possible to suppress oxidation of the surface of the substrate and the surface of the undercoat on the substrate by oxygen in the processing container after the substrate has been loaded into the processing container.

[0041] Furthermore, in the above embodiment, an eighth step may be performed after the graphene film formation step (step S103) in which the interface amorphous layer is modified by heat treatment (annealing) in an atmosphere of a fourth mixed gas containing at least one of hydrogen gas and an inert gas (e.g., argon gas, helium gas, nitrogen gas, etc.). In the eighth step, only the interface amorphous layer can be modified without changing the film quality of the graphene film. The modification of such an interface amorphous layer will be explained with reference to Figures 8A to 8C.

[0042] The inventors sequentially formed an amorphous interface layer and a graphene film on a substrate W, and investigated the bonding strength of the amorphous interface layer when heat treatment (annealing) was performed under hydrogen (H2) gas and nitrogen (N2) gas as the inert gas, respectively. Figures 8A to 8C show examples of analysis results obtained by XPS (X-ray Photoelectron Spectroscopy) analysis of the heat-treated (annealed) substrate W. Figures 8A to 8C show the results of measuring the bonding strength of each bond in the amorphous interface layer when the substrate W, on which the underlying silicon film was formed, was heat-treated (annealed) under hydrogen (H2) gas and nitrogen (N2) gas atmospheres, respectively. The heat treatment (annealing) was performed under the following conditions: temperature: 500°C or higher (e.g., 800°C), flow rate of hydrogen gas and nitrogen gas respectively: 100 to 10000 sccm, and treatment time: 30 minutes or longer.

[0043] In Figures 8A to 8C, "Initial" indicates the bond strength of each bond in the amorphous interface layer before heat treatment (annealing). Also in Figures 8A to 8C, "N2 anl" indicates the bond strength of each bond in the amorphous interface layer after heat treatment (annealing) under a nitrogen gas atmosphere. Also in Figures 8A to 8C, "H2 anl" indicates the bond strength of each bond in the amorphous interface layer after heat treatment (annealing) under a hydrogen gas atmosphere.

[0044] Figure 8A shows that the bond strength of the C-Si bond is slightly reduced by heat treatment (annealing) under the atmospheres of hydrogen (H2) gas and nitrogen (N2) gas, respectively. Figure 8B shows that the bond strength of the C-Si bond is maintained, suggesting that there is no change in the film thickness or quality of the graphene film. Figure 8C shows that the valence of the Si oxide increases from 1 to 3. These results indicate that heat treatment (annealing) can modify only the amorphous interface layer of the graphene film without changing its quality. Furthermore, heat treatment (annealing) makes it possible to control the composition ratios of SiC and SiO.

[0045] Furthermore, in the above embodiments, the case in which the substrate underlayer is a polysilicon (polycrystalline silicon) film or a silicon film was described as an example. However, it is not limited to these, and for example, a metal film such as a titanium (Ti) film may be used as the substrate underlayer.

[0046] [Film deposition apparatus according to one embodiment] Figure 9 is a schematic cross-sectional view showing an example of a film deposition apparatus according to one embodiment. The film deposition apparatus 1 illustrated in Figure 9 is configured, for example, as a plasma processing apparatus using the RLSA® microwave plasma method.

[0047] The film deposition apparatus 1 comprises an apparatus body 10 and a control unit 11 that controls the apparatus body 10. The apparatus body 10 includes a chamber 101, a stage 102, a microwave introduction mechanism 103, a gas supply mechanism 104, and an exhaust mechanism 105.

[0048] The chamber 101 is formed in a substantially cylindrical shape, and an opening 110 is formed in the approximate center of the bottom wall 101a of the chamber 101. The bottom wall 101a is provided with an exhaust chamber 111 that communicates with the opening 110 and protrudes downward. An opening 117 is formed in the side wall 101s of the chamber 101 through which the substrate (hereinafter also referred to as wafer) W passes, and the opening 117 is opened and closed by a gate valve 118. The chamber 101 is an example of a processing container.

[0049] The substrate W to be processed is placed on the stage 102. The stage 102 is roughly disc-shaped and made of ceramics such as AlN. The stage 102 is supported by a cylindrical support member 112 made of ceramics such as AlN that extends upward from approximately the center of the bottom of the exhaust chamber 111. An edge ring 113 is provided on the outer edge of the stage 102 so as to surround the substrate W placed on the stage 102. Inside the stage 102, a lifting pin (not shown) for raising and lowering the substrate W is provided so as to be able to protrude from and retract relative to the upper surface of the stage 102.

[0050] Furthermore, a resistance-heating type heater 114 is embedded inside the stage 102, and the heater 114 heats the substrate W placed on the stage 102 according to the power supplied from the heater power supply 115. Also, a thermocouple (not shown) is inserted into the stage 102, and the temperature of the substrate W can be controlled, for example, between 350 and 850°C, based on the signal from the thermocouple. Furthermore, within the stage 102, an electrode 116 of approximately the same size as the substrate W is embedded above the heater 114, and a bias power supply 119 is electrically connected to the electrode 116. The bias power supply 119 supplies bias power of a predetermined frequency and magnitude to the electrode 116. Ions are drawn into the substrate W placed on the stage 102 by the bias power supplied to the electrode 116. Note that the bias power supply 119 may not be provided depending on the characteristics of the plasma processing.

[0051] The microwave introduction mechanism 103 is located at the top of the chamber 101 and includes an antenna 121, a microwave output unit 122, and a microwave transmission mechanism 123. The antenna 121 has a number of slots 121a, which are through holes. The microwave output unit 122 outputs microwaves. The microwave transmission mechanism 123 guides the microwaves output from the microwave output unit 122 to the antenna 121.

[0052] A dielectric window 124 made of dielectric material is provided below the antenna 121. The dielectric window 124 is supported by a ring-shaped support member 132 provided at the top of the chamber 101. A slow wave plate 126 is provided above the antenna 121. A shielding member 125 is provided above the antenna 121. A flow channel (not shown) is provided inside the shielding member 125, and the shielding member 125 cools the antenna 121, the dielectric window 124, and the slow wave plate 126 with a fluid such as water flowing through the flow channel.

[0053] The antenna 121 is formed from, for example, a copper or aluminum plate with a silver or gold-plated surface, and has multiple slots 121a arranged in a predetermined pattern for radiating microwaves. The arrangement pattern of the slots 121a is set appropriately so that microwaves are radiated evenly. An example of a suitable pattern is a radial line slot, in which multiple pairs of slots 121a are arranged concentrically, with two T-shaped slots 121a forming one pair. The length and spacing of the slots 121a are determined appropriately according to the effective wavelength (λg) of the microwaves. The slots 121a may also have other shapes, such as circular or arc-shaped. Furthermore, the arrangement of the slots 121a is not particularly limited and may be arranged in a spiral or radial pattern in addition to concentric circles. The pattern of the slots 121a is set appropriately so that the microwave radiation characteristics result in a desired plasma density distribution.

[0054] The slow wave plate 126 is made of a dielectric material having a dielectric constant greater than that of a vacuum, such as quartz, ceramics (Al2O3), polytetrafluoroethylene, or polyimide. The slow wave plate 126 has the function of shortening the wavelength of microwaves to a shorter wavelength than that in a vacuum, thereby reducing the size of the antenna 121. The dielectric window 124 is also made of a similar dielectric material.

[0055] The thicknesses of the dielectric window 124 and the slow-wave plate 126 are adjusted so that the equivalent circuit formed by the slow-wave plate 126, antenna 121, dielectric window 124, and plasma satisfies the resonance conditions. By adjusting the thickness of the slow-wave plate 126, the phase of the microwaves can be adjusted. By adjusting the thickness of the slow-wave plate 126 so that the junction of the antenna 121 becomes an antinode of the standing wave, microwave reflection can be minimized and the microwave radiation energy can be maximized. In addition, by using the same material for the slow-wave plate 126 and the dielectric window 124, interfacial reflection of microwaves can be prevented.

[0056] The microwave output unit 122 has a microwave oscillator. The microwave oscillator may be a magnetron type or a solid-state type. The frequency of the microwaves generated by the microwave oscillator is, for example, 300 MHz to 10 GHz. As an example, the microwave output unit 122 outputs microwaves at 2.45 GHz using a magnetron type microwave oscillator. Microwaves are an example of electromagnetic waves.

[0057] The microwave transmission mechanism 123 includes a waveguide 127 and a coaxial waveguide 128. It may also include a mode conversion mechanism. Waveguide 127 guides the microwaves output from the microwave output unit 122. The coaxial waveguide 128 includes an inner conductor connected to the center of the antenna 121 and an outer conductor outside of it. The mode conversion mechanism is provided between waveguide 127 and coaxial waveguide 128. Microwaves output from the microwave output unit 122 propagate through waveguide 127 in TE mode and are converted from TE mode to TEM mode by the mode conversion mechanism. Microwaves converted to TEM mode propagate through coaxial waveguide 128 to the slow wave plate 126 and are radiated from the slow wave plate 126 into chamber 101 through the slot 121a of antenna 121 and the dielectric window 124. Furthermore, a tuner (not shown) is provided in the middle of the waveguide 127 to match the impedance of the load (plasma) in the chamber 101 to the output impedance of the microwave output unit 122.

[0058] The gas supply mechanism 104 has a shower ring 142 provided in a ring shape along the inner wall of the chamber 101. The shower ring 142 has a ring-shaped flow path 166 provided inside and a number of discharge ports 167 connected to the flow path 166 and opening to the inside thereof. The gas supply unit 163 is connected to the flow path 166 via piping 161. The gas supply unit 163 is provided with a plurality of gas sources and a plurality of flow controllers. In one embodiment, the gas supply unit 163 is configured to supply at least one processing gas to the shower ring 142 from a corresponding gas source via a corresponding flow controller. The gas supplied to the shower ring 142 is supplied into the chamber 101 from the plurality of discharge ports 167.

[0059] Furthermore, when a graphene film is formed on the substrate W, the gas supply unit 163 supplies a carbon-containing gas, a hydrogen-containing gas, and a noble gas, controlled to a predetermined flow rate, into the chamber 101 via the shower ring 142. In this embodiment, the carbon-containing gas is, for example, C2H2 gas. In addition to C2H2 gas, C2H4 gas, CH4 gas, C2H6 gas, C3H8 gas, or C3H6 gas may be used instead. In this embodiment, the hydrogen-containing gas is, for example, hydrogen gas. In addition to hydrogen gas, halogen gases such as F2 (fluorine) gas, Cl2 (chlorine) gas, or Br2 (bromine) gas may be used instead. In this embodiment, the noble gas is, for example, Ar gas. In addition to Ar gas, other noble gases such as He gas may be used.

[0060] The exhaust mechanism 105 includes an exhaust chamber 111, an exhaust pipe 181 provided on the side wall of the exhaust chamber 111, and an exhaust device 182 connected to the exhaust pipe 181. The exhaust device 182 includes a vacuum pump and a pressure control valve, etc.

[0061] The control unit 11 includes a memory, a processor, and an input / output interface. The memory stores a program executed by the processor and a recipe that includes conditions for each process. In each step of the film deposition method according to one embodiment, the processor executes the program read from the memory and controls each part of the apparatus body 10 via the input / output interface based on the recipe stored in the memory.

[0062] (Effects of the embodiment) The film deposition method according to the above embodiment includes a loading step (e.g., step S101), a first step (e.g., step S102, interface amorphous layer formation step), and a second step (e.g., step S103, graphene film formation step). The loading step involves loading a substrate (e.g., substrate W) into a processing container (e.g., chamber 101). The first step involves forming an interface layer (e.g., interface amorphous layer 18) having an amorphous structure or microcrystalline structure on the substrate using a plasma of a first mixed gas containing a carbon-containing gas. The second step involves forming a graphene film (e.g., graphene film 19) on the interface layer having an amorphous structure or microcrystalline structure using a plasma of a second mixed gas containing a carbon-containing gas. As a result, according to the film deposition method according to the embodiment, the barrier properties at the interface between the substrate and the graphene film can be improved.

[0063] Furthermore, the first mixed gas may further contain a hydrogen-containing gas. In the first step, the flow rate of the hydrogen-containing gas in the first mixed gas may be controlled to different flow rates over time, thereby changing the composition of the formed interface amorphous layer according to the flow rate of the hydrogen-containing gas. As a result, according to the film formation method of the embodiment, the composition ratio of SiC in the formed interface amorphous layer can be increased or decreased.

[0064] Furthermore, the second mixed gas may further contain a hydrogen-containing gas. The flow rate of the hydrogen-containing gas in the second mixed gas may be greater than or equal to the flow rate of the hydrogen-containing gas in the first mixed gas. As a result, according to the film formation method of this embodiment, the hydrogen-containing gas can contribute as an etching component to unstable carbon bonds, thereby stabilizing the structure of the formed graphene film.

[0065] Furthermore, the substrate may have a base film (e.g., base film 15) made of polycrystalline silicon or silicon. In the first step, an amorphous interface layer may be formed by reacting the active carbon species contained in the plasma of the first mixed gas with an oxygen-containing layer (e.g., native oxide film 17) on the base film. As a result, according to the film formation method of the embodiment, a state can be achieved in which an amorphous interface layer without grain boundaries is located between the substrate base film and the graphene film, thereby improving the barrier properties at the interface between the substrate and the graphene film.

[0066] Furthermore, the substrate may be a silicon substrate without an underlayer (for example, silicon substrate 16). In the first step, an amorphous interface layer may be formed by reacting the active carbon species contained in the plasma of the first mixed gas with the oxygen-containing layer on the silicon substrate. As a result, according to the film formation method of the embodiment, a state can be achieved in which an amorphous interface layer without grain boundaries is located between the silicon substrate and the graphene film, thereby improving the barrier properties at the interface between the silicon substrate and the graphene film.

[0067] Furthermore, the interface amorphous layer may be a layer containing at least one of SiC and SiOC. As a result, according to the film formation method of the embodiment, the grain boundaries of the graphene film can be blocked with an interface amorphous layer that does not have grain boundaries.

[0068] Furthermore, the film deposition method according to the above embodiment may further include a third step between the loading step and the first step, in which the oxygen-containing layer is modified by a plasma of a third mixed gas containing a hydrogen-containing gas. This makes it possible to increase the deposition rate of the interface amorphous layer according to the film deposition method according to the embodiment.

[0069] Furthermore, the film deposition method according to the above embodiment may further include a fourth step between the first and second steps, in which the surface layer of the interface amorphous layer is modified by a plasma of a third mixed gas containing a hydrogen-containing gas. This makes it possible to increase the film deposition rate of the graphene film according to the film deposition method according to the embodiment.

[0070] Furthermore, the film deposition method according to the above embodiment may further include a fifth step of etching the oxygen-containing layer between the loading step and the first step. This makes it possible to increase the deposition rate of the interface amorphous layer according to the film deposition method according to the embodiment.

[0071] Furthermore, the film formation method according to the above embodiment may further include a sixth step between the fifth step and the first step, in which an oxygen-containing gas is supplied into the processing container. This makes it possible to increase the film formation rate of the interfacial amorphous layer according to the film formation method according to the embodiment.

[0072] Furthermore, the film deposition method according to the above embodiment may further include a seventh step in which, before the loading step, oxygen in the processing container is removed by a hydrogen-containing gas plasma while the substrate is not present in the processing container. As a result, according to the film deposition method according to the embodiment, oxidation of the surface of the substrate and the surface of the undercoat on the substrate by oxygen in the processing container after the substrate has been loaded into the processing container can be suppressed.

[0073] [others] In the above-described embodiment, a film deposition apparatus 1 that uses microwave plasma as a plasma source to perform etching, film deposition, and other processing on a wafer W was explained as an example, but the disclosed technology is not limited to this. As long as the apparatus uses plasma to perform processing on a wafer W, the plasma source is not limited to microwave plasma, and any plasma source such as capacitively coupled plasma, inductively coupled plasma, or magnetron plasma can be used.

[0074] It should be noted that the embodiments disclosed herein are illustrative and not restrictive in all respects. Indeed, the embodiments described above can be embodied in a variety of forms. Furthermore, the embodiments described above may be omitted, replaced, or modified in various ways without departing from the scope and spirit of the appended claims. [Explanation of Symbols]

[0075] 1 Film deposition equipment 11 Control Unit 15. Undercoat 16 Silicon substrate 17. Native Oxide Film 18. Amorphous interfacial layer 19 Graphene film 101 Chamber W board

Claims

1. A loading process involves loading a substrate having an oxygen-containing layer on a silicon-containing substrate into a processing container, A first step involves generating a plasma of a first mixed gas containing at least carbon and hydrogen, and reacting the active carbon species contained in the plasma with the oxygen-containing layer on the substrate to form an interface layer having an amorphous structure containing carbon-containing silicon oxide (SiOC). A second step involves forming a graphene film on the interface layer using a plasma of a second mixed gas containing the compound gas. A film deposition method including the above.

2. The first mixed gas and the second mixed gas further contain a hydrogen-containing gas. The film formation method according to claim 1, wherein the flow rate of the hydrogen-containing gas in the second mixed gas is equal to or greater than the flow rate of the hydrogen-containing gas in the first mixed gas.

3. The film formation method according to claim 1, wherein the substrate is polycrystalline silicon or silicon.

4. The film formation method according to claim 1, wherein the substrate is a silicon substrate without an undercoat.

5. The film formation method according to claim 3 or 4, wherein the interface layer further comprises silicon carbide (SiC).

6. The film formation method according to claim 1, further comprising a third step between the loading step and the first step, of modifying the oxygen-containing layer with a plasma of a third mixed gas containing a hydrogen-containing gas.

7. The film formation method according to claim 1, further comprising a fourth step between the first step and the second step of modifying the surface layer of the interface layer with a plasma of a third mixed gas containing a hydrogen gas.

8. The film formation method according to claim 1, further comprising a fifth step of etching the oxygen-containing layer between the loading step and the first step.

9. The film-forming method according to claim 8, further comprising a sixth step of supplying an oxygen-containing gas into the processing container between the fifth step and the first step.

10. The film formation method according to claim 1, further comprising a seventh step of removing oxygen from the processing container by a hydrogen-containing gas plasma before the aforementioned loading step, while the substrate is not present in the processing container.

11. The film-forming method according to claim 1, further comprising an eighth step of modifying the interface layer by performing a heat treatment in an atmosphere of a fourth mixed gas containing at least one of hydrogen gas and an inert gas, after the second step.

12. The method for forming a film according to claim 11, wherein the inert gas is at least one selected from the group consisting of argon gas, helium gas, and nitrogen gas.

13. A processing container capable of housing a substrate, Control unit and It has, The control unit, A loading step involves loading a substrate having an oxygen-containing layer on a silicon-containing substrate into the processing container, A first step involves generating a plasma of a first mixed gas containing at least carbon and hydrogen, and reacting the active carbon species contained in the plasma with the oxygen-containing layer on the substrate to form an interface layer having an amorphous structure containing carbon-containing silicon oxide (SiOC). A second step involves forming a graphene film on the interface layer using a plasma of a second mixed gas containing the compound gas. A film deposition apparatus that controls the execution of a certain process.

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