Film formation method and film formation apparatus

Abstract

To provide a film deposition method and a film deposition apparatus capable of depositing a carbon film having low stress.SOLUTION: A film deposition method has the steps of: mounting a substrate on a substrate mounting table arranged in a treatment container; decompressing an inside of the treatment container by exhausting; generating plasma by applying high frequency power for plasma generation to the substrate mounting table while supplying a treatment gas containing a carbon containing gas into the decompressed treatment container, and depositing a carbon film on the substrate; and applying the high frequency power for plasma generation and performing plasma treatment by applying a negative DC voltage to a counter electrode facing the substrate mounting table.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a film formation method and a film formation apparatus. [Background technology]

[0002] Patent Document 1 describes a method for depositing an amorphous carbon layer for a hard mask, in which an RF power source and a matching network are coupled to a showerhead or to both the showerhead and the wafer pedestal, an electric field is generated between the showerhead and the wafer pedestal, and plasma is formed, which causes plasma pyrolysis of a hydrocarbon compound to deposit an amorphous carbon layer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-12972 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a film formation method and a film formation apparatus that can form a low-stress carbon film. [Means for solving the problem]

[0005] A film formation method according to one aspect of the present disclosure includes the steps of placing a substrate on a substrate mounting table provided in a processing chamber; evacuating the processing chamber to reduce the pressure; supplying a processing gas containing a carbon-containing gas into the reduced-pressure processing chamber while applying high-frequency power for plasma generation to the substrate mounting table to generate plasma and form a carbon film on the substrate; and applying high-frequency power for plasma generation to the substrate mounting table and applying a negative DC voltage to an opposing electrode facing the substrate mounting table to perform plasma processing. [Effects of the Invention]

[0006] According to the present disclosure, a film formation method and a film formation apparatus capable of forming a low-stress carbon film are provided. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a cross-sectional view schematically illustrating an example of a film formation apparatus for performing a film formation method according to a first embodiment. [Figure 2] 3 is a flowchart showing an example of the flow of a film forming method according to the first embodiment. [Figure 3] 1 is a cross-sectional view showing an example of the structure of a substrate used in a film forming method according to a first embodiment. [Figure 4] FIG. 4 is a cross-sectional view showing a state in which a carbon film is formed on the substrate of FIG. [Figure 5] 10A and 10B are diagrams schematically illustrating a state in which a carbon-containing gas is converted into plasma and a carbon film is formed by plasma CVD in step ST3. [Figure 6] 6 is a diagram schematically showing a state when a negative DC voltage is applied to the upper electrode in the state of FIG. 5. FIG. [Figure 7] 10 is a diagram schematically illustrating a state in which carbon particles sputtered and released from the carbon film of the upper electrode are implanted into the carbon film on the substrate by applying a negative DC voltage to the upper electrode. FIG. [Figure 8] This figure shows the conditions of Depo and DCPlasma in an experiment verifying that stress is relieved by implanting carbon particles into a carbon film. [Figure 9] 10A and 10B show the experimental results verifying that stress is alleviated when carbon particles are implanted into a carbon film, where (a) shows the relationship between the time of step ST4 and the carbon film thickness, and (b) shows the relationship between the time of step ST4 and the film stress. [Figure 10] FIG. 10 is a diagram showing the results of an experiment verifying a preferable range of a DC voltage applied to the upper electrode. [Figure 11]10 is a diagram showing the results of an experiment conducted to verify a preferable range of the thickness of the carbon film per cycle when the process of forming the carbon film in step ST3 and the process of applying a DC voltage in step ST4 are alternately repeated. FIG. [Figure 12] 10A and 10B are diagrams showing experimental results verifying the preferred range of pressure in the process of applying a DC voltage in step ST4, where (a) is a diagram showing the relationship between the pressure in step ST4 and the carbon film thickness, and (b) is a diagram showing the relationship between the pressure in step ST4 and the film stress. [Figure 13] 10A and 10B are diagrams showing experimental results verifying the preferable range of HF power in the process of applying a DC voltage in step ST4, where FIG. 10A shows the relationship between the HF power in step ST4 and the carbon film thickness, and FIG. 10B shows the relationship between the HF power in step ST4 and the film stress. [Figure 14] FIG. 10 is a cross-sectional view showing another example of a film forming apparatus. [Figure 15] 10 is a flowchart showing an example of the flow of a film forming method according to a second embodiment. [Figure 16] FIG. 10 is a schematic view illustrating a main part of another film formation apparatus capable of carrying out the film formation method according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments will be described with reference to the accompanying drawings.

[0009] First Embodiment First, the first embodiment will be described.

[0010] [Example of film formation equipment] FIG. 1 is a cross-sectional view schematically showing an example of a film forming apparatus for carrying out a film forming method according to a first embodiment.

[0011] The film forming apparatus 100 of this example is configured as a capacitively coupled plasma processing apparatus, and forms a carbon film suitable for a hard mask on a substrate W. The substrate W may be, for example, a semiconductor wafer, but is not limited to this.

[0012] The film forming apparatus 100 has a substantially cylindrical processing vessel (chamber) 10 made of metal, for example, aluminum whose surface is anodized. The processing vessel 10 is protectively grounded.

[0013] A cylindrical metal support table 14 is disposed at the bottom of the processing vessel 10 via an insulating plate 12 made of ceramic or the like, and a substrate mounting table 16 made of metal, such as aluminum, is provided on the support table 14. The substrate mounting table 16 constitutes a lower electrode. An electrostatic chuck 18 is provided on the upper surface of the substrate mounting table 16, which attracts and holds the substrate W by electrostatic force. The electrostatic chuck 18 has a structure in which an electrode 20 is provided inside an insulator, and when a DC voltage is applied to the electrode 20 from an attracting DC power supply 22, the substrate W is attracted and held by electrostatic force such as Coulomb force.

[0014] To improve the uniformity of plasma processing, a conductive focus ring 24 made of, for example, silicon is disposed around the electrostatic chuck 18. A cylindrical inner wall member 26 made of, for example, quartz is provided on the side surfaces of the substrate mounting table 16 and the support table 14.

[0015] A coolant chamber 28 is provided inside the support table 14. A coolant, for example, cooling water, is circulated and supplied to the coolant chamber 28 from an external chiller unit (not shown) via pipes 30a and 30b, and the processing temperature of the substrate W on the substrate mounting table 16 is controlled by the coolant.

[0016] Furthermore, a heat transfer gas, for example, He gas, is supplied between the upper surface of the electrostatic chuck 18 and the rear surface of the substrate W from a heat transfer gas supply mechanism (not shown) via a gas supply line 32 .

[0017] A first high-frequency power supply 88 for generating plasma and a second high-frequency power supply 91 for applying a bias are electrically connected to the substrate mounting table 16, which serves as the lower electrode. A matching box 87 is provided on a power feed line 89 that supplies power from the first high-frequency power supply 88 to the substrate mounting table 16. A power feed line 92 from the second high-frequency power supply 91 is connected to the power feed line 89, and a matching box 90 is provided on the power feed line 92. The first high-frequency power supply 88 has a higher frequency than the second high-frequency power supply 91. The frequency of the high-frequency power supplied from the first high-frequency power supply 88 is preferably 40 MHz or higher. Furthermore, the frequency of the high-frequency power supplied from the second high-frequency power supply 91 is preferably 3.2 MHz or lower. As an example, the first high-frequency power supply 88 may have a frequency of 40 MHz, and the second high-frequency power supply 91 may have a frequency of 3.2 MHz. The power of the high frequency power supplied from the first high frequency power supply 88 is preferably in the range of 100 W to 1 kW, and the power of the high frequency power supplied from the second high frequency power supply 91 is preferably in the range of 500 W to 5 kW.

[0018] The matching devices 87 and 90 are used to match the load (plasma) impedance to the impedance on the side of the first and second high frequency power supplies 88 and 91, respectively. That is, the matching devices 87 and 90 function to make the internal impedance of the first and second high frequency power supplies 88 and 91 and the load impedance appear to match when plasma is generated in the processing vessel 10.

[0019] An upper electrode 34 is provided above the substrate mounting table (lower electrode) 16 so as to face the substrate mounting table 16. The space between the upper electrode 34 and the substrate mounting table (lower electrode) 16 serves as a plasma generation space.

[0020] The upper electrode 34 is supported on the top of the processing chamber 10 via an insulating shielding member 43. The upper electrode 34 is composed of an electrode plate 36, which faces the substrate mounting table 16 and has multiple gas discharge holes 37, and an electrode support 38, which detachably supports the electrode plate 36. The electrode plate 36 is made of a conductor, such as commonly used silicon, but may also be made of carbon, as described below. A gas diffusion chamber 40 is provided inside the electrode support 38, and multiple gas flow holes 41 extending downward from the gas diffusion chamber 40 communicate with the gas discharge holes 37. A gas inlet 42 is formed in the electrode support 38 to introduce processing gas into the gas diffusion chamber 40. A gas pipe 51, which is connected to a gas supply unit 50 (described below), is connected to the gas inlet 42. The processing gas supplied from the gas supply unit 50 is supplied to the gas diffusion chamber 40, and then is supplied to the processing vessel 10 through the gas flow holes 41 and the gas discharge holes 37 toward the substrate mounting table 16, which is the lower electrode. In other words, the upper electrode 34 is configured as a shower head.

[0021] A DC power supply 94 for applying a negative DC voltage is electrically connected to the upper electrode 34 via a power supply line 95. A low-pass filter 93 is connected to the power supply line 95 downstream of the DC power supply 94. The low-pass filter 93 prevents high-frequency power from the high-frequency power supplies 88 and 91 from being supplied to the DC power supply 94. The absolute value of the DC voltage from the DC power supply 94 is preferably 300 V or more.

[0022] The gas supply unit 50 supplies a carbon-containing gas (C x H yThe system has a plurality of gas supply sources that supply gases such as rare gases, e.g., Ar gas, He gas, and hydrogen gas (H2 gas), and a plurality of gas supply pipes for supplying each gas from these gas supply sources. Each gas supply pipe is provided with an on-off valve and a flow rate controller such as a mass flow controller (neither of which is shown), which enable the supply and stop of the gas and the flow rate of each gas to be controlled. In this example, He gas and Ar gas are supplied as rare gases, but this is not limiting, and for example, only Ar gas or another rare gas may be used. Alternatively, only a carbon-containing gas may be used.

[0023] An exhaust port 60 is provided at the bottom of the processing vessel 10, and an exhaust device 64 is connected to the exhaust port 60 via an exhaust pipe 62. The exhaust device 64 has an automatic pressure control valve and a vacuum pump, and is capable of evacuating the processing vessel 10 and maintaining the processing vessel 10 at a desired vacuum level. A load / unload port 65 is provided on the sidewall of the processing vessel 10 for loading and unloading the substrate W into and out of the processing vessel 10, and the load / unload port 65 is configured to be opened and closed by a gate valve 66. A removable deposit shield (not shown) is provided along the inner wall of the processing vessel 10 to prevent etching by-products (deposits) from adhering to the processing vessel 10.

[0024] Components of the film forming apparatus 100, such as the valves and flow rate controllers of the gas supply unit 50, the high-frequency power supplies 88 and 91, and the DC power supply 94, are controlled by a control unit 80. The control unit 80 has a main control unit with a CPU, an input device, an output device, a display device, and a storage device. The control unit 80 controls the processing of the film forming apparatus 100 based on a processing recipe stored in a storage medium of the storage device.

[0025] [Film forming method] Next, a film forming method according to the first embodiment, which is carried out by the film forming apparatus of FIG. 1, will be described.

[0026] FIG. 2 is a flowchart showing an example of the flow of the film forming method according to the first embodiment. As shown in FIG. 2, in this embodiment, steps ST1 to ST4 are performed.

[0027] In step ST1, the substrate W is loaded into the processing chamber 10 and placed on the substrate placement table 16. At this time, the temperature of the substrate placement table 16 is preferably set so that the temperature of the placed substrate W is 150° C. or less. The substrate W may be, for example, a semiconductor wafer. As shown in FIG. 3, an example of the semiconductor wafer that is the substrate W is a substrate in which an underlayer film 102 is formed on a Si base 101. The underlayer film 102 may be a SiO2 film (for example, a thermal oxide film) or a SiN x Examples include Si-containing films such as films.

[0028] In step ST2, the inside of the processing chamber 10 is evacuated to reduce the pressure. At this time, an inert gas, such as a rare gas such as Ar gas or He gas, is supplied while evacuating the inside of the processing chamber 10. The pressure inside the processing chamber 10 is preferably 20 mTorr (2.66 Pa) or less.

[0029] In step ST3, while supplying a process gas containing a carbon-containing gas into the reduced-pressure processing chamber 10, plasma is generated by applying plasma-generating high-frequency power from the first high-frequency power supply 88 to the substrate mounting table 16, which serves as the lower electrode, to form a carbon film on the substrate. As a specific example, as shown in FIG. 4, a carbon film 103 is formed on the base film 102 of the substrate W in FIG. 3. During step ST3, it is preferable to perform a step of applying a bias from the second high-frequency power supply 91 to the substrate mounting table 16. Applying a bias from the second high-frequency power supply 91 to the substrate mounting table 16 can reduce stress on the carbon film.

[0030] The carbon-containing gas used to generate plasma may be, for example, acetylene (C2H2) gas. In addition to acetylene (C2H2) gas, other carbon-containing gases include methane (CH4) gas, ethylene (C2H4) gas, ethane (C2H6) gas, propylene (C3H6) gas, propyne (C3H4) gas, propane (C3H8) gas, and butane (C4H 10 ) gas, butylene (C4H8) gas, butadiene (C4H6) gas, and phenylacetylene (C8H6) gas can be used. A mixed gas containing multiple gases selected from these gases may also be used. A rare gas may also be added in addition to the carbon-containing gas. Ar gas or He gas can be used as the rare gas.

[0031] In step ST4, plasma processing is performed by applying high-frequency power from the high-frequency power supply 88 to the substrate mounting table 16, which is the lower electrode, and applying a negative DC voltage from the DC power supply 94 to the upper electrode 34, which is the counter electrode facing the substrate mounting table 16. During the plasma processing in step ST4, a rare gas such as Ar gas is introduced into the processing chamber 10 to generate plasma. At this time, hydrogen gas (H2 gas) may be added together with the rare gas. The following model can be considered for the effect of adding H2 gas.

[0032] First, consider the case of plasma processing using only a rare gas, such as Ar gas. Carbon atoms sputtered by the rare gas from the upper electrode 34, which is the counter electrode facing the substrate stage 16, are delivered to the substrate without bonding with other atoms. Depending on the ion energy of the carbon atoms, they are implanted into the substrate surface to a depth of several atomic layers. After implantation, the carbon atoms reorganize nearby carbon bonds, resulting in a structural change in the film. However, if the carbon atoms are suddenly implanted into a film that is structurally stable before implantation, the dangling bonds of the carbon atoms may not reorganize to form stable bonds with neighboring carbon atoms, and may remain unstable at the implanted positions. In this case, the unstable dangling bonds may cause local film stress or become reaction sites with moisture in the atmosphere when the film is exposed to the atmosphere after deposition. On the other hand, when hydrogen is added to the rare gas, the carbon atoms sputtered from the upper electrode 34, which is the counter electrode facing the substrate stage, bond with dissociated hydrogen to form CH x In this case, some of the dangling bonds are terminated with hydrogen before penetrating the substrate, so that film reconstruction is likely to occur when the dangling bonds are implanted into the substrate surface, which may result in a reduction in film stress.

[0033] A similar phenomenon can occur in normal plasma CVD film formation. For example, when a film is formed by plasma CVD using a carbon-containing gas such as CH4, hydrogen dissociates from the CH4 molecule through various collision processes, resulting in the formation of CH4. x However, the difference between this embodiment and the conventional method is believed to be the following point. That is, in this embodiment, the distance between the electrodes is on the order of several centimeters, and the pressure zone is a low pressure zone of several tens of mTorr, and so on, an appropriate amount of hydrogen adheres to the carbon atoms sputtered from the counter electrode, and at that time, a more carbon-rich CH xis generated, which is thought to effectively relieve film stress when implanted into the substrate.

[0034] In step ST4, stress on the carbon film formed on the substrate W can be alleviated by applying a DC voltage to the upper electrode 34, which is the counter electrode.

[0035] The specific details will be explained below. The carbon film formed by plasmatizing a carbon-containing gas is an amorphous carbon film, and sp 3 This film is composed of diamond-like carbon with a high bond ratio, and has high density and etching resistance, making it suitable for next-generation hard masks.

[0036] On the other hand, hard masks are required to have not only high density but also low film stress. In other words, even for films with the same stress, the thicker the film, the greater the warpage of the substrate due to film stress. If the film thickness required for a hard mask is 1 μm or more, the warpage may exceed the allowable substrate warpage (e.g., 200 μm) for transportation and lithography, making it difficult to perform post-processing after film formation. However, carbon films formed using conventional carbon-containing gas plasmas exhibit high film stress as the film density increases. In other words, there is a trade-off between film density and film stress; the higher the film density, the higher the film stress, making it difficult to obtain a high-density, low-stress carbon film.

[0037] In this embodiment, when the carbon-containing gas is turned into plasma and a carbon film is formed by plasma CVD in step ST3, as shown in FIG. 5, the carbon film 201 is formed on the substrate W, and at the same time, a carbon film (C x H yThe amount of the carbon film 201 deposited on the substrate W may be considered to be approximately the same as the amount of the carbon film deposited on the substrate W, although this depends on the potential state of the surface. For example, if a carbon film 201 with a thickness of 5 nm is deposited on the substrate W, the carbon film 202 deposited on the upper electrode 34 will also be approximately 5 nm. In this state, when a negative DC voltage is applied to the upper electrode 34 in step ST4, as shown in FIG. 6, secondary electrons 203 are emitted from the upper electrode 34, and ions (e.g., argon ions) 204 in the plasma are attracted to the upper electrode 34 and sputter the carbon film 202 on its surface, forming carbon particles (C x H y 7, the carbon particles 205 having higher energy are implanted into the carbon film 201 formed on the substrate W, which is thought to relieve the stress in the carbon film 201.

[0038] This was verified through an experiment. The electrode plate 36 of the upper electrode 34 was made of silicon, and a film was formed by applying a DC voltage to the upper electrode 34 while generating a high-frequency plasma. The relationship between film formation time and film stress was investigated. As shown in FIG. 8, the carbon film deposition (Depo) time in step ST3 was set to 5 seconds, and the DC voltage application plasma treatment (DCPlasma) time in step ST4 was varied. This process was repeated eight times. The deposition conditions were: pressure: 20 mTorr; 40 MHz high-frequency power (HF) power: 400 W; 3.2 MHz high-frequency power (LF) power: 500 W; DC voltage: -75 V; carbon-containing gas: C2H2 gas; and C2H2 gas / Ar gas flow rates: 50 / 100 sccm. The DC plasma conditions were a pressure of 100 mTorr, HF power of 400 W, DC: -900 V, and H2 gas / Ar gas flow rates of 200 / 500 sccm.

[0039] The results are shown in Figure 9. Figure 9(a) shows the relationship between DCPlasma time and carbon film thickness, and (b) shows the relationship between DCPlasma time and film stress (compressive). As shown in Figure 9(a), there was a tendency for the film thickness to increase as the DCPlasma time increased. Furthermore, as shown in Figure 9(b), film samples with DCPlasma times up to 20 seconds showed a significant stress reduction effect, but at 30 seconds the stress reduction effect saturated. Furthermore, in samples with a DC voltage application time of up to 20 seconds, the film formed on the substrate was a carbon film, whereas silicon was detected in the film in samples with an application time of 30 seconds.

[0040] This indicates that the carbon film deposited on the upper electrode 34 (electrode plate 36), which is the opposing electrode, is sputtered during plasma processing, and carbon particles are implanted into the film on the substrate, thereby reducing film stress, but that no stress reduction occurs when the carbon film is completely sputtered and silicon is sputtered instead.

[0041] Furthermore, from the results of this experiment, it can be concluded that if the electrode plate 36 is made of carbon, the effect of mitigating film stress is maintained even if the carbon film deposited on the electrode plate 36 is completely sputtered.

[0042] In the step ST4 of applying a DC voltage to perform plasma processing, the absolute value of the DC voltage applied from the DC power supply 94 to the upper electrode 34 is preferably 300V or more.

[0043] The experimental results verifying this are shown in Figure 10. Here, the Depo conditions were the same as those in Figure 8, and the DCPlasma conditions were the same as those in Figure 8, except that the time was fixed at 5 seconds and the DC voltage was varied between -300 and -900V.

[0044] As shown in Figure 10, as the absolute value of the DC voltage increases from 300V, the film thickness increases and the effect of reducing film stress becomes greater. It is believed that the higher the absolute value of the DC voltage, the greater the amount of carbon sputtering from the top plate, so the higher the value, the better. However, depending on the equipment, there are restrictions on the DC power supply specifications, and in the experiment shown in Figure 10, the maximum absolute value of the DC voltage was set to 900V.

[0045] As shown in the experimental results in Figure 9, it is preferable to alternately repeat the carbon film deposition process in step ST3 and the DC voltage application process in step ST4. This allows carbon particles to be implanted into the carbon film after a thin carbon film is deposited on the substrate W, thereby enhancing the stress relaxation effect of the carbon particle implantation. In this case, it is preferable to set the thickness of the carbon film to 10 nm or less in each step.

[0046] Figure 11 shows the experimental results verifying this. Here, the case where deposition was performed for 40 seconds under the same conditions as in Figure 8 without DCPlasma was designated as Reference. Cases 1 to 3 were cases where DCPlasma was fixed at 20 seconds and the deposition time and the number of cycles for steps ST3 and ST4 were varied. The deposition and DCPlasma conditions were the same as in Figure 8 except for the time. Specifically, as shown in Table 1, in Case 1 the deposition time was 5 seconds and the number of cycles was 8, in Case 2 the deposition time was 10 seconds and the number of cycles was 4, and in Case 3 the deposition time was 20 seconds and the number of cycles was 2. The film thickness per cycle was 10 nm in Case 1, 20 nm in Case 2, and 40 nm in Case 3.

[0047] [Table 1]

[0048] As shown in Figure 11, in all of Cases 1 to 3, the film stress was lower than that of the reference film, and in particular, the film stress was lowest in Case 1. This confirmed that the sequence of performing DCPlasma every 10 nm or less of film thickness by Depo has a high stress reduction effect.

[0049] In the process of applying a DC voltage in step ST4, the higher the pressure at that time, the more effective the stress reduction can be, and the pressure at that time is preferably 30 mTorr (4 Pa) or more.

[0050] The experimental results verifying this are shown in Figure 12. Here, the pressure during DCPlasma was varied between 30 and 100 mTorr, and eight cycles of Depo and DCPlasma were repeated for 5 seconds each. The Depo conditions were the same as in Figure 8, and the DCPlasma conditions, except for time and pressure, were the same as in Figure 8.

[0051] Figure 12(a) shows the relationship between DCPlasma pressure and carbon film thickness, and (b) shows the relationship between DCPlasma pressure and film stress (compressive). As shown in Figure 12(a), as the DCPlasma pressure increases, the film thickness tends to increase. Also, as shown in Figure 12(b), as the DCPlasma pressure increases, the film stress tends to decrease, confirming that the higher the pressure in step ST4, the greater the stress reduction effect.

[0052] In the process of applying a DC voltage in step ST4, the higher the high frequency power (HF power) from the first high frequency power supply 88 for plasma generation, the greater the film stress reduction effect, and it is preferable that the power be 200 W or more.

[0053] The results of an experiment verifying this are shown in Figure 13. Here, the HF power during DCPlasma was varied between 200W, 400W, and 800W, and eight cycles of Depo and DCPlasma were repeated for 5 seconds each. The Depo conditions were the same as in Figure 8, and the DCPlasma conditions, except for the time and HF power, were the same as in Figure 8.

[0054] Figure 13(a) shows the relationship between DCPlasma HF power and carbon film thickness, and (b) shows the relationship between DCPlasma HF power and film stress (compressive). As shown in Figure 13(a), as the DCPlasma HF power increases, the film thickness tends to increase. Also, as shown in Figure 13(b), as the DCPlasma HF power increases, the film stress tends to decrease, confirming that the higher the HF power in step ST4, the greater the stress reduction effect.

[0055] In the film forming apparatus 100 of FIG. 1, the second high frequency power supply 91 applies a high frequency power for bias application having a frequency (for example, 3.2 MHz) lower than that for plasma generation, but a DC bias may also be applied.

[0056] Fig. 14 is a cross-sectional view showing an example of a film formation apparatus that applies a DC bias. In the film formation apparatus 100' of Fig. 14, a DC power supply 97 for applying a bias is electrically connected to a substrate mounting table 16, which serves as a lower electrode. A power feeder 98 from the DC power supply 97 for applying a bias is connected to a power feeder 89 of a first high-frequency power supply 88, and a DC voltage from the DC power supply 97 for applying a bias is applied to the substrate mounting table 16 via the power feeder 98 and the power feeder 89. A low-pass filter 96 is provided in the power feeder 98 connected to the DC power supply 97 to prevent high-frequency power from the first high-frequency power supply 88 from being supplied to the DC power supply 97. The negative electrode of the DC power supply 97 is connected to the substrate mounting table 16.

[0057] The other components of the film forming apparatus 100' in FIG. 14 are the same as those of the film forming apparatus 100 in FIG. 1, and therefore the same reference numerals are used and the description thereof will be omitted.

[0058] <Second embodiment> Next, a film forming method according to a second embodiment will be described. 15 is a flowchart showing an example of the flow of the film forming method according to the second embodiment. This embodiment can be performed using the film forming apparatus 100' shown in FIG. As shown in FIG. 15, in this embodiment, steps ST11 to ST15 are performed.

[0059] In step ST11, the substrate W is carried into the processing chamber 10 and placed on the substrate mounting table 16. This step ST11 is performed in the same manner as step ST1 in the first embodiment.

[0060] In step ST12, the inside of the processing chamber 10 is evacuated and reduced in pressure. This step ST12 is performed in the same manner as step ST2 in the first embodiment.

[0061] In step ST13, plasma is generated by applying plasma-generating high-frequency power from the first high-frequency power supply 88 to the substrate mounting table 16, which is the lower electrode, while supplying a process gas containing a carbon-containing gas into the depressurized process chamber 10. Step ST13 is performed in the same manner as step ST3 in the first embodiment.

[0062] Steps ST14 and ST15 are alternately performed during the period in which the carbon film is formed in step ST13. That is, steps ST14 and ST15 are alternately performed while the high frequency power is continuously applied from the high frequency power supply 88 to the substrate mounting table 16 in step ST13 and the gas containing the carbon-containing gas is continuously supplied into the processing chamber 10.

[0063] In step ST14, a bias DC voltage is applied from the DC power supply 97 to the substrate mounting table 16. Similar to the high-frequency bias in the first embodiment, this DC bias has the effect of reducing stress on the carbon film being deposited. The bias DC voltage applied to the substrate mounting table 16 is a negative DC voltage, and is preferably 500 to 3 kV. Note that step ST14 may also be performed by applying a high-frequency bias to the substrate mounting table 16 from the second high-frequency power supply 91 using the film formation apparatus 100 of FIG. 1.

[0064] In step ST15, similarly to step ST4 in the first embodiment, a negative DC voltage is applied from the DC power supply 94 to the upper electrode 34, which is the counter electrode, to perform plasma processing.

[0065] In this way, the application of a DC bias to the substrate mounting table 16 in step ST14 reduces the stress on the carbon film to be deposited, and the application of a DC voltage to the upper electrode 34 in step ST15 implants carbon particles into the deposited carbon film, thereby reducing the film stress. During the deposition of the carbon film in step ST13, the stress reduction of the carbon film to be deposited itself in step ST14 and the stress relaxation of the deposited carbon film in step ST15 are alternately repeated, thereby obtaining a carbon film with low stress.

[0066] Steps ST14 and ST15 can be achieved by switching the application of DC voltage to the substrate mounting table 16 (lower electrode) and the upper electrode 34, and can be performed at high speed, thereby enhancing the stress relaxation effect of the carbon film in step ST15.

[0067] In this embodiment, steps ST14 and ST15 can be achieved by switching the application of DC voltages to the substrate table 16 (lower electrode) and the upper electrode 34. Therefore, a single DC power supply may be used to switch the DC voltages applied to the substrate table 16 and the upper electrode 34. An example of such a film formation apparatus is shown in FIG. 16. FIG. 16 is a schematic diagram illustrating the main components of such a film formation apparatus. The film formation apparatus 100″ of this example has a single DC power supply 110, and the negative pole of the DC power supply 110 is connected to a switch 111. The switch 111 is connected to the upper electrode 34 by a power supply line 112 and to the substrate table 16 (lower electrode) by a power supply line 113. Low-pass filters 114 and 115 are installed in the power supply lines 112 and 113, respectively, to prevent high-frequency power from the first high-frequency power supply 88 from being supplied to the DC power supply 110.

[0068] With this configuration, by switching the switch 111, the application of DC voltage from a single DC power supply 110 can be switched between the substrate mounting table 16 and the upper electrode 34 to perform steps ST14 and ST15, thereby realizing a film formation apparatus with a simpler structure.

[0069] <Other applications> Although the embodiments have been described above, the disclosed embodiments should be considered to be illustrative and not restrictive in all respects. The above embodiments may be omitted, substituted, or modified in various ways without departing from the scope and spirit of the appended claims.

[0070] For example, the film forming apparatus of the above embodiment is merely an example, and apparatuses of various configurations can be used. Also, although the case where a semiconductor wafer is used as the substrate has been described, the substrate is not limited to a semiconductor wafer, and may be other substrates such as an FPD (flat panel display) substrate, typified by an LCD (liquid crystal display) substrate, or a ceramic substrate. [Explanation of symbols]

[0071] 10. Processing container 16;Substrate mounting table (lower electrode) 34;Top electrode 50: Gas supply unit 64;Exhaust system 80;Control unit 88: First high frequency power supply 91: Second high frequency power supply 94, 97, 110; DC power supply 100, 100´, 100″; Film deposition equipment 101;Si substrate 102; Base film 103; Carbon film 111;Switch 201; Carbon film on substrate 202: Carbon film (C) deposited on the upper electrode x H y film) 203;Secondary electron 204;Ion 205; Carbon particles (C x H y ) W; substrate

Claims

1. placing a substrate on a substrate placement table provided in a processing chamber; evacuating the processing vessel to reduce the pressure; a step of applying high frequency power for plasma generation to the substrate mounting table to generate plasma while supplying a process gas containing a carbon-containing gas into the depressurized processing vessel, and forming a carbon film on the substrate; a step of applying high frequency power for generating plasma to the substrate mounting table and applying a negative DC voltage to a counter electrode facing the substrate mounting table to perform plasma processing; The film forming method includes the steps of:

2. 2. The film forming method according to claim 1, further comprising the step of applying a bias high frequency power or a DC voltage to the substrate mounting table during the step of forming the carbon film.

3. 3. The film forming method according to claim 1, wherein the step of applying a negative DC voltage to the counter electrode to perform the plasma treatment is carried out in a state where the gas containing the carbon-containing gas is not supplied.

4. 4. The film forming method according to claim 1, wherein the step of forming the carbon film and the step of applying a negative DC voltage to the counter electrode to perform the plasma treatment are alternately repeated.

5. The film forming method according to claim 4 , wherein the carbon film forming step forms a carbon film having a thickness of 10 nm or less per step.

6. 6. The film forming method according to claim 4, wherein a step of applying a bias high frequency power or a DC voltage to the substrate mounting table is not performed during a step of performing the plasma processing by applying a negative DC voltage to the opposing electrode.

7. 7. The film forming method according to claim 4, wherein the step of applying a negative DC voltage to the counter electrode to perform the plasma treatment is performed at a pressure of 4 Pa ​​or more.

8. 8. The film forming method according to claim 2, wherein the DC voltage applied to the counter electrode during the step of applying a negative DC voltage to the counter electrode to perform the plasma treatment has an absolute value of 300 V or more.

9. 9. The film forming method according to claim 1, wherein the power of the high frequency power for plasma generation applied during the step of applying a negative DC voltage to the counter electrode to perform the plasma treatment is 200 W or more.

10. The method further includes applying a bias DC voltage to the substrate mounting table, 2. The film forming method according to claim 1, wherein, during the step of forming the carbon film, a step of applying a bias DC voltage to the substrate mounting table and a step of applying a negative DC voltage to the counter electrode to perform plasma processing are alternately repeated.

11. 11. The film forming method according to claim 10, wherein the step of applying a negative DC voltage to the counter electrode to perform plasma processing and the step of applying a bias DC voltage to the substrate mounting table are performed by switching DC voltages from a single DC power supply.

12. a processing vessel for accommodating a substrate; a substrate mounting table for mounting a substrate in the processing chamber; a counter electrode provided opposite the substrate mounting table; a gas supply unit that supplies a gas used for processing into the processing vessel; an exhaust unit that exhausts the processing vessel to reduce the pressure inside the processing vessel; a high frequency power source that supplies high frequency power for generating plasma to the substrate mounting table; a DC power supply that applies a negative DC voltage to the counter electrode; A control unit; and The control unit With the substrate placed on the substrate placement table, controlling the exhaust unit to reduce the pressure inside the processing vessel to a desired level; a step of applying high frequency power for plasma generation to the substrate mounting table to generate plasma while supplying a process gas containing a carbon-containing gas into the depressurized processing vessel, and forming a carbon film on the substrate; a step of applying high frequency power for generating plasma to the substrate mounting table and applying a negative DC voltage to a counter electrode facing the substrate mounting table to perform plasma processing; The film forming apparatus controls the gas supply unit, the exhaust unit, the high frequency power supply, and the DC power supply so that the above-mentioned is performed.

13. the film forming apparatus further includes a bias power supply that applies a bias high-frequency power or a DC voltage to the substrate mounting table; 13. The film forming apparatus according to claim 12, wherein the control unit controls the apparatus to further execute a step of applying a bias high frequency power or a DC voltage to the substrate mounting table during the step of forming the carbon film.

14. 14. The film forming apparatus according to claim 12, wherein the control unit controls the step of forming the carbon film and the step of applying a negative DC voltage to the counter electrode to perform the plasma treatment so as to alternately repeat the steps.

15. 15. The film forming apparatus according to claim 14, wherein the control unit controls the step of applying a negative DC voltage to the counter electrode to perform the plasma treatment in a state where the gas containing the carbon-containing gas is not supplied.

16. 16. The film forming apparatus according to claim 14, wherein the control unit controls so as not to perform a step of applying a bias high frequency power or a DC voltage to the substrate mounting table during a period in which a DC voltage is applied to the counter electrode.

17. the film forming apparatus further includes a bias power supply that applies a bias DC voltage to the substrate mounting table; the control unit controls the process to further perform a step of applying a bias DC voltage to the substrate mounting table, 13. The film forming apparatus according to claim 12, wherein, during a period in which the carbon film forming step is performed, control is performed so that a step of applying a negative DC voltage to the counter electrode to perform plasma processing and a step of applying a bias DC voltage to the substrate mounting table are alternately repeated.

18. the DC power supply and the bias power supply are a common DC power supply, 18. The film formation apparatus according to claim 17, wherein the control unit controls the process of applying a negative DC voltage to the counter electrode to perform plasma processing and the process of applying a bias DC voltage to the substrate mounting table to be performed by switching the DC voltage from the common DC power supply.

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