Deposition method and deposition device for carbon-based film

Abstract

To suppress the formation of carbon-based film overhangs and also improve the throughput when the carbon-based film is formed selectively on tops of a pattern of trenches, holes, etc.SOLUTION: A deposition device executes deposition processing such that a wafer W is held at a temperature at least higher than 200°C and the rate of addition of a hydrogen gas to a deposition gas consisting of only an acethylene gas, an argon gas, and the hydrogen gas is set to 3% or higher.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a method and an apparatus for forming a carbon-based film.

Background Art

[0002] In semiconductor devices, in order to realize wiring with a more complex shape and fine wiring, a technique for selectively forming a carbon-based film on the top of trenches and holes formed in a mask or an etching target film is known. For example, in the technique described in Patent Document 1, a carbon-based film is formed on the top of a trench formed in a substrate made of silicon. Specifically, in the substrate, a fluid film which is an amorphous carbon polymer film is mainly deposited on the bottom of the trench, and then the fluid film at the bottom is exposed to nitrogen plasma to etch the fluid film at the bottom, and gaseous C x N y H z species are formed. At this time, since the adhesion coefficient of C x N y H z species to the fluid film at the bottom is lower than the adhesion coefficient of C x N y H z species to the top of the trench where silicon is exposed, C x N y H z species are selectively redeposited on the top of the trench. As a result, a carbon-based film is selectively formed on the top of the trench.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The technology according to the present disclosure suppresses the generation of overhang of the carbon-based film and improves throughput when selectively forming a carbon-based film on the top of a pattern such as a trench or a hole.

Means for Solving the Problems

[0005] One aspect of the technology according to the present disclosure is a method for forming a carbon-based film, which includes a film-forming step of forming a carbon-based film on a substrate having a pattern. In the film-forming step, plasma is generated from a film-forming gas consisting only of a hydrocarbon gas, an argon gas, and a hydrogen gas, and the carbon-based film is selectively formed on the top of the pattern.

Effects of the Invention

[0006] According to the technology of the present disclosure, when selectively forming a carbon-based film on the top of a pattern such as a trench or a hole, the generation of overhang of the carbon-based film can be suppressed and the throughput can be improved.

Brief Description of the Drawings

[0007]

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Embodiments for Carrying Out the Invention

[0008] By the way, in the technique described in Patent Document 1, after depositing a fluid film on the bottom of the trench, re-depositing the carbon-based film on the top of the trench by exposure to nitrogen plasma is required, so two steps are necessary for forming the carbon-based film on the top of the trench, and the throughput decreases.

[0009] In addition, in the technology described in Patent Document 1, when the re-deposition of the carbon-based film progresses to the top of the trench, an overhang of the carbon-based film may occur, which may block the trench.

[0010] On the other hand, the technology according to the present disclosure suppresses the occurrence of overhang of the carbon-based film and improves throughput when selectively forming a carbon-based film on the top of a pattern such as a trench or a hole.

[0011] Hereinafter, an embodiment of the technology according to the present disclosure will be described with reference to the drawings. FIG. 1 is a cross-sectional view schematically showing the configuration of a film forming apparatus as this embodiment. This film forming apparatus is a PECVD (Plasma-Enhanced Chemical Vapor Deposition) apparatus that generates plasma from a film forming gas to perform film formation.

[0012] In FIG. 1, a film forming apparatus 100 includes a substantially cylindrical chamber 11 (processing chamber) that houses a wafer W (substrate). In the chamber 11, plasma is generated from a film forming gas inside as will be described later. The chamber 11 has a loading / unloading port 12 on the side wall for loading and unloading the wafer W into and out of the interior, and the loading / unloading port 12 is opened and closed by a gate valve 13.

[0013] Inside the chamber 11, a substantially disk-shaped mounting table 14 is disposed, and the mounting table 14 mounts the wafer W. Further, an annular guide ring 15 is disposed at the outer edge of the mounting table 14 so as to surround the mounted wafer W. The mounting table 14 is supported by a cylindrical support member 16 extending upward from the bottom of the chamber 11.

[0014] Furthermore, a lower electrode 17, a heater 18, and a refrigerant passage (not shown) are embedded inside the mounting table 14. The heater 18 generates heat by the electric power supplied from a heater power supply 19 to heat the mounted wafer W, and the refrigerant passage cools the mounted wafer W by circulating refrigerant supplied from the outside. In addition, in order to improve the heat transfer property between the mounting table 14 and the wafer W, a heat transfer gas is supplied between the mounting table 14 and the wafer W.

[0015] Also, an upper electrode 20 is disposed on the ceiling portion of the chamber 11 so as to face the mounting table 14, and an insulating member 21 is disposed between the chamber 11 and the upper electrode 20. The upper electrode 20 includes a base member 22, a top plate 23, and an intermediate member 24. The base member 22, the top plate 23, and the intermediate member 24 are made of a conductive member, for example, an aluminum material. The top plate 23, the intermediate member 24, and the base member 22 are arranged in this order from below, but the top plate 23 and the base member 22 are separated by a substantially annular intermediate member 24 to form a gas diffusion space 25 therebetween. A gas introduction port 26 communicating with the gas diffusion space 25 from above is formed in the base member 22, while a plurality of gas holes 27 communicating the gas diffusion space 25 with the inside of the chamber 11 are formed in the top plate 23.

[0016] The film forming apparatus 100 further includes a gas supply unit 28, and the gas supply unit 28 is connected to the gas introduction port 26 via a gas pipe 29. The gas supply unit 28 has a gas source, a flow rate controller, and an opening / closing valve, and supplies a processing gas to be plasmaized, for example, a film forming gas. The supplied film forming gas is introduced into the gas diffusion space 25 through the gas introduction port 26, and further diffuses and is introduced into the chamber 11 from each gas hole 27. Thereby, the upper electrode 20 functions as a shower head. A heat insulating member 30 is disposed on the upper electrode 20. In the present embodiment, the film forming gas supplied by the gas supply unit 28 consists only of acetylene gas (hydrocarbon gas), argon gas, and hydrogen gas.

[0017] The film forming apparatus 100 further includes an exhaust device 31. The exhaust device 31 is composed of, for example, a turbo molecular pump or a dry pump, and the exhaust device 31 decompresses the inside of the chamber 11 through an exhaust pipe 31a connected to the bottom of the chamber 11.

[0018] The film forming apparatus 100 further includes a high-frequency power supply 32, and the high-frequency power supply 32 is connected to the upper electrode 20 via a matching unit 33. The matching unit 33 matches the impedance of the load of the high-frequency power supply 32 with the output impedance of the high-frequency power supply 32. The high-frequency power supply 32 supplies high-frequency power with a frequency of 40 MHz to 460 MHz to the upper electrode 20.

[0019] Therefore, in the film forming apparatus 100, high-frequency power with a frequency of 40 MHz or higher is supplied to the upper electrode 20. Generally, when generating plasma by supplying high-frequency power with a frequency of 40 MHz or higher to the upper electrode 20, the generated plasma becomes high-density plasma, and the electrical impedance of the plasma decreases. As a result, the maximum value of the high-frequency voltage applied to the upper electrode 20 becomes lower than when supplying a low-frequency voltage (frequency: 200 kHz to 13 MHz). That is, when supplying high-frequency power to the upper electrode 20, due to the decrease in the plasma potential, the sheath voltage contributing to the acceleration of ions in the plasma decreases. In addition, since the sheath vibrates at a higher speed as the applied voltage becomes higher frequency, the followability of ions to the sheath voltage decreases. As a result, the ion energy applied from the plasma to the wafer W placed on the mounting table 14 is reduced.

[0020] The film forming apparatus 100 further includes a control unit 34, and the control unit 34 controls each component of the film forming apparatus 100. The control unit 34 is a computer including a processor, a memory, an input device, a display device, an input / output interface for signals, etc., and a control program and recipe data are stored in the memory of the control unit 34. In the film forming apparatus 100, when executing a film forming process, the processor of the control unit 34 executes the corresponding control program and controls each component of the film forming apparatus 100 according to the recipe data.

[0021] Specifically, the control unit 34 controls the gas supply unit 28 and the exhaust device 31 to adjust the pressure inside the chamber 11, and controls the high-frequency power supply 32 to supply high-frequency power to the upper electrode 20. Further, the control unit 34 controls the gas supply unit 28 to diffuse and introduce the film-forming gas into the chamber 11. At this time, each gas molecule of the film-forming gas is excited by the electric field generated by the high-frequency power supplied to the upper electrode 20, plasma is generated, and the wafer W is subjected to a film-forming process by this plasma.

[0022] The film-forming apparatus 100 further includes a first impedance circuit 35. The first impedance circuit 35 is disposed in a first electrical path 37 that connects the lower electrode 17 and the ground. The first impedance circuit 35 includes at least one of an inductor and a capacitor, and can change the impedance between the lower electrode 17 and the ground by connecting them in series or in parallel. Further, the inductor and capacitor included in the first impedance circuit 35 may be either fixed elements or variable elements.

[0023] By changing this impedance, it is also possible to control so as to weaken the electrical coupling between the upper electrode 20 and the lower electrode 17 and further reduce the high-frequency current flowing through the lower electrode 17. As a result, the energy value of the ions incident on the wafer W can be controlled more precisely.

[0024] Incidentally, the applicant of the present application used an evaluation apparatus 40 having a similar structure to the film-forming apparatus 100 of FIG. 1, changed the temperature of the wafer W and the addition rate of hydrogen gas in the film-forming gas, performed a film-forming process on the wafer W, and confirmed the film-forming form of the carbon-based film on the wafer W. Note that the temperature of the wafer W in the present embodiment is actually the temperature of the mounting table 14 on which the wafer W is mounted.

[0025] The configuration of the evaluation apparatus 40 is shown simplified in Fig. 16(A), and the configurations other than those shown are the same as those of the film forming apparatus 100. In the evaluation apparatus 40, high-frequency power with an extremely high frequency, for example, high-frequency power with a frequency higher than 40 MHz, is supplied from the high-frequency power supply 32 to the upper electrode 20. The plasma generated at this time becomes high-density plasma, and the electrical impedance of the plasma decreases. As a result, the voltage amplitude Vpp at the upper electrode 20 decreases, so the plasma potential between the upper electrode 20 and the lower electrode 17 decreases, and the sheath voltage decreases. In addition, since the sheath vibrates at high speed, the followability of ions to the sheath voltage decreases. As a result, similar to the film forming apparatus 100, the ion energy applied to the wafer W placed on the mounting table 14 is reduced. That is, the film forming process in the film forming apparatus 100 can be reproduced by the evaluation apparatus 40.

[0026] Fig. 2 is a diagram showing the film forming form when the temperature of the wafer W is changed during the film forming process in the evaluation apparatus 40. In Fig. 2, an enlarged partial cross section of an oxide layer 44 formed on the surface of a wafer W having silicon as a base material 43 and having a plurality of trenches as patterns formed therein is shown. Note that the oxide layer 44 is an underlayer of the carbon-based film 45 to be formed.

[0027] At this time, the applicant set the addition rate of acetylene gas in the film forming gas to 3% (flow rate: 30 sccm), the addition rate of argon gas to 94% (flow rate: 1000 sccm), and the addition rate of hydrogen gas to 3% (flow rate: 30 sccm). Note that the addition rate of each gas in this embodiment is the flow rate ratio of each gas to the total gas flow rate of the film forming gas. Then, the pressure inside the chamber 11 was set to 1 Torr, high-frequency power with a frequency of 40 MHz was supplied from the high-frequency power supply 32 to the upper electrode 20 at 500 W, and plasma was generated from the film forming gas to perform a film forming process on the wafer W. Also, the temperature of the wafer W was set to 200°C and 400°C.

[0028] FIG. 2(A) shows the film formation morphology of the carbon-based film 45 when the film formation process is performed with the temperature of the wafer W set at 200°C, and FIG. 2(B) shows the film formation morphology of the carbon-based film 45 when the film formation process is performed with the temperature of the wafer W set at 400°C.

[0029] First, when the temperature of the wafer W was set at 200°C, it was confirmed that at the top of the fin 44a (corresponding to the top of the trench) sandwiched between the trenches of the oxide layer 44, the carbon-based film 45 was formed so as to overhang and block the trench. Also, it was confirmed that the carbon-based film 45 was formed inside the trench as well. That is, it was confirmed that an inappropriate carbon-based film 45 was formed as the carbon-based film to be selectively formed on the top of the fin 44a. On the other hand, when the temperature of the wafer W was set at 400°C, the carbon-based film 45 was formed only on the top of the fin 44a, the carbon-based film 45 did not overhang toward the trench, and it was confirmed that the carbon-based film 45 was hardly formed inside the trench. That is, it was confirmed that an appropriate carbon-based film 45 was formed as the carbon-based film to be selectively formed on the top of the fin 44a.

[0030] Furthermore, without changing the flow rates of acetylene gas and argon gas in the film formation gas, the present applicant changed the hydrogen gas addition rate to 10% (flow rate: 100 sccm), and then set the temperature of the wafer W at 300°C. Then, plasma was generated from the film formation gas to perform a film formation process on the wafer W. The film formation morphology of the carbon-based film 45 at this time is shown in FIG. 2(C).

[0031] When the temperature of the wafer W was set at 300°C as well, the carbon-based film 45 was formed only on the top of the fin 44a, the carbon-based film 45 did not overhang toward the trench, and it was confirmed that the carbon-based film 45 was hardly formed inside the trench. That is, similar to when the temperature of the wafer W was set at 400°C, it was confirmed that an appropriate carbon-based film 45 was formed as the carbon-based film to be selectively formed on the top of the fin 44a.

[0032] FIG. 3 is a diagram showing the film formation morphology when the addition rate of hydrogen gas in the film formation gas is changed during the film formation process in the evaluation apparatus 40. Also in FIG. 3, similar to FIG. 2, an enlarged partial cross-section of the oxide layer 44 in which a plurality of trenches are formed on the surface of the wafer W is shown.

[0033] At this time, the applicant set the pressure inside the chamber 11 to 1 Torr and the temperature of the wafer W to 400°C. Further, high-frequency power with a frequency of 40 MHz was supplied from the high-frequency power supply 32 to the upper electrode 20 at 500 W, and plasma was generated from the film formation gas to perform a film formation process on the wafer W. Then, the flow rate of acetylene gas in the film formation gas was set to 30 sccm, the flow rate of argon gas was set to 1000 sccm, and the addition rates of hydrogen gas in the film formation gas were set to 1.7% and 3%.

[0034] FIG. 3(A) shows the film formation morphology of the carbon-based film 45 when the film formation process is performed with the addition rate of hydrogen gas set to 1.7%, and FIG. 3(B) shows the film formation morphology of the carbon-based film 45 when the film formation process is performed with the addition rate of hydrogen gas set to 3%.

[0035] First, when the addition rate of hydrogen gas was set to 1.7%, although the carbon-based film 45 was formed only on the top of the fin 44a, it was confirmed that the carbon-based film 45 swelled in the lateral direction and overhung toward the trench. That is, it was confirmed that an inappropriate carbon-based film 45 was formed as the carbon-based film to be selectively formed on the top of the fin 44a. On the other hand, when the addition rate of hydrogen gas was set to 3%, the carbon-based film 45 was formed only on the top of the fin 44a, and it was confirmed that the carbon-based film 45 did not overhang toward the trench and that the carbon-based film 45 was hardly formed inside the trench. That is, it was confirmed that an appropriate carbon-based film 45 was formed as the carbon-based film to be selectively formed on the top of the fin 44a.

[0036] Similar to FIG. 3, FIG. 4 is a diagram showing the film formation morphology when the addition rate of hydrogen gas in the film formation gas is changed during the film formation process in the evaluation apparatus 40.

[0037] At this time, the applicant of the present application set the pressure inside the chamber 11 to 1 Torr and the temperature of the wafer W to 350°C. Further, high-frequency power with a frequency of 40 MHz was supplied from the high-frequency power supply 32 to the upper electrode 20 at 500 W, and plasma was generated from the film-forming gas to perform a film-forming process on the wafer W. Then, the flow rate of acetylene gas in the film-forming gas was set to 30 sccm, the flow rate of argon gas was set to 1000 sccm, and the addition rates of hydrogen gas in the film-forming gas were set to 2% (flow rate: 20 sccm) and 4% (flow rate: 40 sccm).

[0038] FIG. 4(A) shows the film-forming morphology of the carbon-based film 45 when the film-forming process is performed with the addition rate of hydrogen gas set to 2%, and FIG. 4(B) shows the film-forming morphology of the carbon-based film 45 when the film-forming process is performed with the addition rate of hydrogen gas set to 4%.

[0039] First, when the addition rate of hydrogen gas was set to 2%, similar to the case when the addition rate of hydrogen gas was set to 1.7%, although the carbon-based film 45 was formed only at the top of the fin 44a, it was confirmed that the carbon-based film 45 bulged laterally and overhung toward the trench. That is, it was confirmed that an inappropriate carbon-based film 45 was formed as the carbon-based film to be selectively formed on the top of the fin 44a. On the other hand, when the addition rate of hydrogen gas was set to 4%, it was confirmed that the carbon-based film 45 was formed only at the top of the fin 44a, the carbon-based film 45 did not overhang toward the trench, and almost no carbon-based film 45 was formed inside the trench. That is, it was confirmed that an appropriate carbon-based film 45 was formed as the carbon-based film to be selectively formed on the top of the fin 44a.

[0040] From the confirmation results shown in FIGS. 2 to 4, it was found that as the temperature of the wafer W and the addition rate of hydrogen gas increased, the overhang of the carbon-based film 45 formed on the top of the fin 44a decreased, and there was a phenomenon that it became difficult for the carbon-based film 45 to be formed inside the trench. As the reason for such a phenomenon, the applicant of the present application speculated the mechanism described below.

[0041] FIG. 5 is a diagram for explaining the influence of the temperature of the wafer W and the addition rate of hydrogen gas in the film-forming gas on the film-forming form of the carbon-based film 45.

[0042] First, the film-forming form when the temperature of the wafer W is low and the addition rate of hydrogen gas is low, as shown in FIG. 5(A), will be described.

[0043] By the way, the plasma generated from acetylene gas, which is the main factor in the film formation of the carbon-based film 45, contains hydrocarbon ions and hydrocarbon radicals. The hydrocarbon ions have strong anisotropy and adhere to the fins 44a of the oxide layer 44 almost vertically. On the other hand, the hydrocarbon radicals have strong isotropy and adhere to the fins 44a of the oxide layer 44 from all directions.

[0044] When the temperature of the wafer W is low, the ambient temperature near the wafer W also becomes low. When the ambient temperature is low, the adhesion probabilities of hydrocarbon radicals and hydrocarbon ions remain high. Therefore, the hydrocarbon ions mainly deposit vertically on the tops of the fins 44a, and the hydrocarbon radicals deposit not only on the tops of the fins 44a but also on the sides of the fins 44a and the bottoms of the trenches. For easy understanding, in FIG. 5(A), the carbon-based film derived from hydrocarbon ions is indicated by reference numeral 45a, and the carbon-based film derived from hydrocarbon radicals is indicated by reference numeral 45b. However, actually, the carbon-based film derived from hydrocarbon ions and the carbon-based film derived from hydrocarbon radicals are mixed to form the carbon-based film 45.

[0045] By the way, the carbon-based film 45 is isotropically etched by hydrogen radicals contained in hydrogen plasma generated from hydrogen gas. However, when the ambient temperature is low, the etching power by hydrogen radicals is weak and hardly etches the carbon-based film 45. In the figure, the magnitude of the etching power is schematically shown by the length of the arrow.

[0046] As a result, when the temperature of the wafer W is low, the growth of the carbon-based film 45 proceeds on the side surface and the top of the fin 44a and the bottom of the trench. In particular, on the top of the fin 44a, not only the carbon-based film 45b derived from hydrocarbon radicals grows, but also the carbon-based film 45a derived from hydrocarbon ions grows significantly, so that the growth of the carbon-based film 45 is remarkable and overhangs toward the trench.

[0047] Next, the film formation morphology when the temperature of the wafer W is high and the addition rate of hydrogen gas is high, as shown in FIG. 5(B), will be described.

[0048] When the temperature of the wafer W is high, the ambient temperature in the vicinity of the wafer W also becomes high. However, when the ambient temperature is high, although the adhesion probability of hydrocarbon ions remains high, the adhesion probability of hydrocarbon radicals decreases. Therefore, the hydrocarbon ions are deposited vertically on the top of the fin 44a, but the degree of deposition of hydrocarbon radicals on the side surface of the fin 44a and the bottom of the trench decreases. That is, the carbon-based film 45a derived from hydrocarbon ions formed on the top of the fin 44a has the same thickness as when the temperature of the wafer W is low. However, the carbon-based film 45b derived from hydrocarbon radicals formed on the side surface of the fin 44a and the bottom of the trench becomes very thin compared to the case where the temperature of the wafer W is low (FIG. 5(B)).

[0049] In addition, when the ambient temperature is high, the etching power by hydrogen radicals increases, and the carbon-based film 45 is etched isotropically. Then, inside the trench, the thin carbon-based film 45b derived from hydrocarbon radicals is removed by etching, and it becomes difficult to form the carbon-based film 45 inside the trench. Furthermore, even on the top of the fin 44a, the thin carbon-based film 45b derived from hydrocarbon radicals is removed by etching, and only the thick carbon-based film 45a derived from hydrocarbon ions remains. As a result, the growth of the carbon-based film 45 is suppressed to some extent and does not overhang toward the trench.

[0050] In addition, the applicant used the evaluation apparatus 40 to change the aspect ratio (length-to-width ratio) of the trenches in the oxide layer 44, perform a film-forming process on the wafer W, and confirm the film-forming morphology of the carbon-based film on the wafer W. FIG. 6 is a diagram showing the film-forming morphology when the aspect ratio of the trenches in the oxide layer 44 is changed in the wafer W on which the film-forming process is performed. Also in FIG. 6, a partial cross-section of the enlarged oxide layer 44 is shown, similar to FIG. 2.

[0051] At this time, the applicant set the pressure inside the chamber 11 to 1 Torr and the temperature of the wafer W to 370°C. Also, high-frequency power with a frequency of 40 MHz was supplied from the high-frequency power supply 32 to the upper electrode 20 at 500 W, and plasma was generated from the film-forming gas to perform a film-forming process on the wafer W. Then, the addition rate of acetylene gas in the film-forming gas was set to 3% (flow rate: 30 sccm), the addition rate of argon gas was set to 94% (flow rate: 1000 sccm), and the addition rate of hydrogen gas was set to 3% (flow rate: 30 sccm).

[0052] FIG. 6(A) shows the film-forming morphology of the carbon-based film 45 when a film-forming process is performed on the wafer W with the aspect ratio of the trenches in the oxide layer 44 set to 4. FIG. 6(B) shows the film-forming morphology of the carbon-based film 45 when a film-forming process is performed on the wafer W with the aspect ratio of the trenches in the oxide layer 44 set to 2.

[0053] First, in the wafer W with the trench aspect ratio set to 4, the carbon-based film 45 was formed only on the top of the fin 44a. It was confirmed that the carbon-based film 45 did not overhang toward the trench and was hardly formed inside the trench. That is, it was confirmed that the appropriate carbon-based film 45 was formed as the carbon-based film to be selectively formed on the top of the fin 44a. Also, in the wafer W with the trench aspect ratio set to 2, the carbon-based film 45 was formed not only on the top of the fin 44a but also inside the trench. However, the carbon-based film 45 inside the trench was very thin and was a film that could be removed by simply performing light ashing later. And the carbon-based film 45 on the top of the fin 44a did not overhang toward the trench. Therefore, it was confirmed that the generally appropriate carbon-based film 45 was formed as the carbon-based film to be selectively formed on the top of the fin 44a.

[0054] From the confirmation results shown in FIG. 6, it was found that if the aspect ratio of the trench of the oxide layer 44 is 2 or more, the generally appropriate carbon-based film 45 is formed as the carbon-based film to be selectively formed on the top of the fin 44a. On the other hand, it was found that there is a phenomenon that it becomes difficult to form the carbon-based film 45 inside the trench when the aspect ratio of the trench is high. As the reason for such a phenomenon, the applicant of the present application speculated the mechanism described below.

[0055] FIG. 7 is a diagram for explaining the influence of the trench aspect ratio on the film formation form of the carbon-based film 45. In FIG. 7, hydrocarbon ions are indicated by "○" and hydrocarbon radicals are indicated by "●".

[0056] As described above, the carbon-based film 45 inside the trench is mainly formed by the attachment of highly isotropic hydrocarbon radicals. And there are also hydrocarbon radicals that are incident obliquely to the trench. Here, as shown in FIG. 7(A), when the aspect ratio of the trench is low, the opening of the trench widens, and hydrocarbon radicals that are incident obliquely to the trench can easily enter the trench and attach to the side wall of the fin 44a and the bottom of the trench. Therefore, when the aspect ratio is low, the carbon-based film 45 tends to be easily formed inside the trench.

[0057] On the other hand, as shown in FIG. 7(B), when the aspect ratio of the trench is high, the opening of the trench becomes narrow, and hydrocarbon radicals that are incident obliquely to the trench are inhibited by the top of the fin 44a (shielding effect). Also, even if the hydrocarbon radicals enter the trench and attach to the side wall of the fin 44a, since the area of the side wall of the fin 44a increases, the adhesion density of the hydrocarbon radicals decreases, and it becomes difficult to form a thick carbon-based film 45 on the side wall of the fin 44a. Furthermore, since the probability of the hydrocarbon radicals attaching to the side wall of the fin 44a before reaching the bottom of the trench also increases, it becomes difficult for the hydrocarbon radicals to reach the bottom of the trench, and it becomes difficult to form a thick carbon-based film 45 on the bottom of the trench. Therefore, when the aspect ratio is high, the carbon-based film 45 tends to be difficult to be formed inside the trench.

[0058] Also, the applicant of the present application used the evaluation apparatus 40 to change the ion energy of the plasma generated when performing a film-forming process on a wafer W provided with trenches in the oxide layer 44 having an aspect ratio (length-to-width ratio) of 4, and confirmed the film-forming form of the carbon-based film on the wafer W. FIG. 8 is a diagram showing the film-forming form when the ion energy of the plasma is changed in the wafer on which the film-forming process is performed. Also in FIG. 8, similar to FIG. 2, an enlarged partial cross-section of the oxide layer 44 is shown.

[0059] At this time, the applicant of the present application set the pressure inside the chamber 11 to 1 Torr and the temperature of the wafer W to 370°C. Further, high-frequency power with a frequency of 40 MHz was supplied from the high-frequency power supply 32 to the upper electrode 20 at 500 W, 1 kW, or 2 kW in order to change the ion energy of the plasma, and plasma was generated from the film-forming gas to perform a film-forming process on the wafer W. Then, the addition rate of acetylene gas in the film-forming gas was set to 3% (flow rate: 30 sccm), the addition rate of argon gas was set to 94% (flow rate: 1000 sccm), and the addition rate of hydrogen gas was set to 3% (flow rate: 30 sccm).

[0060] Furthermore, the applicant of the present application evaluated the maximum value of the ion energy when the high-frequency power was changed to 500 W, 1 kW, and 1.5 kW respectively during the above-described film-forming process using an ion energy measuring device. And it was confirmed that the maximum values of the ion energy at each high-frequency power were 100 eV, 200 eV, and 300 eV respectively.

[0061] FIG. 8(A) shows the film-forming morphology of the carbon-based film 45 under the condition that high-frequency power with a frequency of 40 MHz is supplied at 500 W and the maximum value of the ion energy is 100 eV. FIG. 8(B) shows the film-forming morphology of the carbon-based film 45 under the condition that high-frequency power with a frequency of 40 MHz is supplied at 1 kW and the maximum value of the ion energy is 200 eV. FIG. 8(C) shows the film-forming morphology of the carbon-based film 45 under the condition that high-frequency power with a frequency of 40 MHz is supplied at 1.5 kW and the maximum value of the ion energy is 300 eV.

[0062] First, as shown in FIG. 8(A), under the condition that the maximum value of the ion energy is 100 eV, the carbon-based film 45 is formed only on the top of the fin 44a, and it was confirmed that the carbon-based film 45 does not overhang toward the trench and is hardly formed inside the trench. That is, it was confirmed that an appropriate carbon-based film 45 was formed as the carbon-based film to be selectively formed on the top of the fin 44a.

[0063] Also, as shown in Fig. 8(B), under the condition that the maximum value of the ion energy is 200 eV, not only at the top of the fin 44a but also at the bottom of the trench, the carbon-based film 45 was formed. However, the carbon-based film 45 at the bottom of the trench was very thin and was a film that could be removed by simply performing light ashing later. And the carbon-based film 45 at the top of the fin 44a did not overhang toward the trench. Therefore, it was confirmed that a generally appropriate carbon-based film 45 was formed as the carbon-based film to be selectively formed on the top of the fin 44a.

[0064] On the other hand, as shown in Fig. 8(C), under the condition that the maximum value of the ion energy is 300 eV, a large amount of the carbon-based film 45 was formed on the top of the fin 44a. Although the carbon-based film 45 at the top of this fin 44a did not overhang toward the trench, the carbon-based film 45 was also formed at the bottom of the trench. And the carbon-based film 45 at the bottom of the trench had a certain thickness and was a film that could not be removed by simply performing light ashing later.

[0065] That is, from the confirmation results shown in Fig. 8, it was found that if the maximum value of the ion energy of the plasma used in the film formation process is 200 eV or less, almost no carbon-based film 45 is formed at the bottom of the trench, and the carbon-based film 45 can be selectively formed on the top of the fin 44a. On the other hand, if the maximum value of the ion energy of the plasma used in the film formation process is 300 eV or more, a carbon-based film 45 having a certain thickness is formed at the bottom of the trench, and it was found that it is difficult to selectively form the carbon-based film 45 on the top of the fin 44a.

[0066] The applicant qualitatively investigated by plasma state calculation the reason why the formation of the carbon-based film on the bottom of the trench can be suppressed by reducing the maximum value of the ion energy of the plasma. FIG. 9 is a diagram schematically showing the calculation results of the angular distribution of the ion energy when the maximum value of the ion energy of the plasma used for the film formation process is different. FIG. 9(A) shows the case where the maximum value of the ion energy is 100 eV, and FIG. 9(B) shows the case where the maximum value of the ion energy is 300 eV. Also, the arrows in FIG. 9 indicate the magnitude of the ratio of ions at the corresponding angles.

[0067] The applicant performed a calculation (simulation) on the plasma state under the film formation conditions for realizing the shape of a predetermined carbon-based film 45. From the calculation results at this time, it was found that as the maximum value of the ion energy of the plasma is increased, the angular distribution of the ion energy changes due to the improvement of the ion energy. Specifically, when the maximum value of the ion energy is low, for example, 100 eV, it was found that the angular distribution of the ion energy becomes broader (wider range) compared to the case where the maximum value of the ion energy is high, for example, 300 eV. Furthermore, when the maximum value of the ion energy is 100 eV, it was difficult for a difference to occur between the ratios of ions at each angle (FIG. 9(A)). On the other hand, when the maximum value of the ion energy is 300 eV, the angular distribution of the ion energy becomes narrow (narrow range), a difference occurs between the ratios of ions at each angle, and in particular, the ratio of ions at the angle of incidence perpendicular to the wafer W increases (FIG. 9(B)).

[0068] The applicant conjectured the reason why the formation of the carbon-based film on the bottom of the trench can be suppressed by reducing the maximum value of the ion energy of the plasma from the above-described calculation results as follows. That is, when the maximum value of the ion energy decreases and the angular distribution of the ion energy becomes broad, the ratio of ions incident at an angle obliquely to the wafer W increases. Then, compared with the case where the maximum value of the ion energy is high, the ratio of ions at an angle perpendicular to the wafer W relatively decreases. Coupled with the fact that there is a certain distance from the plasma high-density region 53 to the wafer W, ions other than those at an angle completely perpendicular to the wafer W are less likely to reach the bottom of the trench. As a result, the formation of the carbon-based film 45 on the bottom of the trench is suppressed.

[0069] In addition, the ions contributing to the film formation on the side surface of the trench are ions at an angle perpendicular to the wafer W or an angle close to perpendicular. When the maximum value of the ion energy of the plasma decreases and the angular distribution of the ion energy becomes broad, such ions decrease. That is, when the maximum value of the ion energy of the plasma is decreased, the formation of the carbon-based film 45 on the side surface of the trench is also suppressed. At this time, it was also found that when the temperature of the wafer W is high, combined with the improvement of the etching force by the hydrogen radicals, a phenomenon occurs in which the carbon-based film 45 is formed only on the top of the fin 44a.

[0070] Furthermore, the applicant performed a film formation process on the wafer W using a film formation apparatus having different configurations in order to investigate an appropriate form for implementing the technology of the present disclosure. The configurations of the film formation apparatuses used at this time are simplified and shown in FIG. 16.

[0071] In each film formation apparatus, the applicant set the temperature of the wafer W to 400°C. In addition, although the addition rate of acetylene gas in the film formation gas varies depending on the film formation apparatus, in any film formation apparatus, it was adjusted to be at least 3% or more (flow rate is 30 sccm or more). Furthermore, the other components of the film formation gas are argon gas and hydrogen gas, and the flow rate of the argon gas was set to 1000 sccm.

[0072] Figure 10(A) is a diagram showing the film formation morphology when a film formation process is performed on a wafer W using the film formation apparatus (evaluation apparatus) 40 shown in Figure 16(A). At this time, the pressure inside the chamber 11 was set to 1 Torr, and high-frequency power with a frequency of 40 MHz was supplied from the high-frequency power supply 32 to the upper electrode 20 at 500 W. Figure 10(B) is a diagram showing the film formation morphology when a film formation process is performed on a wafer W using the film formation apparatus 52 shown in Figure 16(B). At this time, the pressure inside the chamber 11 was set to 100 mTorr, and high-frequency power with a frequency of 13.56 MHz was supplied from the high-frequency power supply 32 to the upper electrode 20 at 1 kW. Also, the electrode plate 222 was connected to the ground, and a positive voltage of 100 V was applied to the electrode plate 221. Figure 10(C) is a diagram showing the film formation morphology when a film formation process is performed on a wafer W using the film formation apparatus 54 shown in Figure 16(C). At this time, the pressure inside the chamber 11 was set to 1 Torr, and high-frequency power with a frequency of 450 kHz was supplied from the high-frequency power supply 32 to the upper electrode 20 at 1 kW.

[0073] Incidentally, at this time, the applicant confirmed by an ion energy measuring instrument that the maximum value of the ion energy of the plasma was 200 eV or less when performing the film formation process in each film formation apparatus. Then, the applicant observed the film formation morphologies shown in Figure 10(A), Figure 10(B), and Figure 10(C), and confirmed that even though the configurations of the film formation apparatuses were different, the carbon-based film 45 was formed only on the top of the fin 44a, the carbon-based film 45 did not overhang toward the trench, and almost no carbon-based film 45 was formed inside the trench. When observing the film formation morphology of the carbon-based film 45 shown in Figure 10(B) in more detail, it was confirmed that a thin carbon-based film 45 was formed on the side surface of the trench, but this carbon-based film 45 was very thin and was a film that could be removed by simply performing ashing later. That is, it was confirmed that a generally appropriate carbon-based film 45 was formed as the carbon-based film to be selectively formed on the top of the fin 44a in the film formation apparatuses 40, 52, and 54.

[0074] As described above, in this embodiment, it has been found that in order to selectively form an appropriate carbon-based film 45 on the top of the fin 44a of the fin 44a, it is necessary to set the temperature of the wafer W to be higher than at least 200 ° C, preferably 300 ° C or higher. Further, it has been found that it is necessary to set the addition rate of hydrogen gas in the film-forming gas composed only of acetylene gas, argon gas, and hydrogen gas to 3% or more. Furthermore, it has been found that the aspect ratio of the trench of the underlying layer on which the carbon-based film 45 is formed needs to be set to 2 or more, preferably 4 or more. More preferably, it has been found that it is necessary to control the maximum value of the ion energy of the plasma used for the film-forming process to 200 eV or less.

[0075] Further, according to this embodiment, in the film-forming apparatus 100, the temperature of the wafer W is set to be higher than at least 200 ° C, and the addition rate of hydrogen gas in the film-forming gas is set to 3% or more, and the film-forming process is executed. Thereby, an appropriate carbon-based film 45 can be selectively formed on the top of the fin 44a of the oxide layer 44 in one step. That is, when the carbon-based film 45 is selectively formed on the top of the trench, the generation of the overhang of the carbon-based film 45 can be suppressed, and the throughput can be improved.

[0076] Next, an application example of the carbon-based film forming method according to this embodiment will be described. As described above, since the carbon-based film forming method according to this embodiment utilizes the change in the adhesion probability of hydrocarbon radicals due to temperature and the change in the etching force due to hydrogen radicals due to temperature, the underlying layer of the carbon-based film does not affect the formation of the carbon-based film. Therefore, the carbon-based film forming method according to this embodiment can be applied not only to an insulating film or a mask whose underlying layer is made of an oxide, but also to a wiring layer whose underlying layer is made of a metal.

[0077] FIG. 11 is a process diagram showing a case where a carbon-based film is selectively formed on the top of a metal protrusion as a wiring layer protruding from an interlayer insulating film. In FIG. 11, first, in a wafer W, metal is embedded in each trench of an interlayer insulating film 46 in which a plurality of trenches are formed to form a wiring layer 47. At this time, the upper surface of the interlayer insulating film 46 and the upper surface of the wiring layer 47 are planarized by CMP (Chemical Mechanical Polishing) or the like (FIG. 11(A)).

[0078] Next, the wafer W is subjected to ashing to selectively remove the interlayer insulating film 46, resulting in a recessed shape in which the interlayer insulating film 46 is recessed. At this time, the wiring layer 47 protrudes relative to the interlayer insulating film 46, constituting a metal protrusion 47a (FIG. 11(B)).

[0079] Thereafter, in a film forming apparatus 100, the wafer W is accommodated inside a chamber 11 and placed on a mounting table 14, and an evacuation device 31 evacuates the inside of the chamber 11. At this time, a heater 18 heats the mounting table 14 and sets the temperature of the mounting table 14 to a temperature higher than 200°C. Further, a gas supply unit 28 supplies a film forming gas composed only of acetylene gas, argon gas, and hydrogen gas through an upper electrode 20. The addition rate of hydrogen gas in the supplied film forming gas is set to 3% or more. Also, a high-frequency power supply 32 supplies high-frequency power to the upper electrode 20. At this time, plasma is generated from the film forming gas, and the wafer W is subjected to a film forming process, and a carbon-based film 48 is selectively formed on the top of the metal protrusion 47a of the wiring layer 47 (FIG. 11(C)) (film forming step).

[0080] Next, the wafer W is subjected to a film forming process of an insulating film to grow the interlayer insulating film 46 so as to fill the recessed shape. Also at this time, the upper surface of the interlayer insulating film 46 and the upper surface of the carbon-based film 48 are planarized by CMP or the like (FIG. 11(D)).

[0081] Thereafter, the wafer W is subjected to ashing to completely remove the carbon-based film 48. At this time, the upper part of the interlayer insulating film 46 is also removed simultaneously. However, since the etching rate of the carbon-based film 48 is higher than that of the interlayer insulating film 46, a recessed shape in which the wiring layer 47 is recessed is formed (FIG. 11(E)).

[0082] Next, a via hole 47b is formed through reformation of the interlayer insulating film 46 and partial addition of the wiring layer 47 (FIG. 11(F)). At this time, by reformation of the interlayer insulating film 46, a sufficient separation distance L between the via hole 47b and the wiring layer 47 adjacent to the via hole 47b is ensured.

[0083] FIG. 12 is a process diagram showing an example of selectively forming a carbon-based film on the top of the trench of the hard mask. In FIG. 12, first, using a hard mask 50 having a plurality of trenches, the oxide layer 49 underlying the hard mask 50 is etched on the wafer W (FIG. 12(A)). As a result of the etching of the oxide layer 49, trenches are also formed in the oxide layer 49 corresponding to the trenches of the hard mask 50, but the hard mask 50 also wears out (FIG. 12(B)).

[0084] Next, in the film forming apparatus 100, a film forming process is performed on the wafer W under the same conditions as in the example of FIG. 11. At this time, a carbon-based film 51 is selectively formed on the top of the trench of the worn-out hard mask 50, and the carbon-based film 51 extends the trench of the worn-out hard mask 50 (FIG. 12(C)) (film forming step). Note that the aspect ratio of the trench of the oxide layer 49 when the film forming process is performed is 2 or more.

[0085] Next, the oxide layer 49 is etched on the wafer W. At this time, since the carbon-based film 51 functions as a mask, the trench of the oxide layer 49 extends corresponding to the trench of the carbon-based film 51. Note that during the etching of the oxide layer 49, the carbon-based film 51 is consumed and only a very small part of the carbon-based film 51 remains (FIG. 12(D)).

[0086] Thereafter, the wafer W is subjected to ashing to completely remove the remaining carbon-based film 51 and the consumed hard mask 50 (FIG. 12(E)). Thereby, trenches with a high aspect ratio can be formed in the oxide layer 49.

[0087] FIG. 13 is a process diagram showing another example of selectively forming a carbon-based film on the top of the trench of the hard mask. In FIG. 13, first, in the film forming apparatus 100, a film forming process is performed on the wafer W on which the hard mask 50 having a plurality of trenches is formed under the same conditions as in the example of FIG. 11. At this time, a carbon-based film 51 is selectively formed on the top of the trench of the hard mask 50, and the carbon-based film 51 extends the trench of the hard mask 50 (FIG. 13(A)) (film forming step). Note that the aspect ratio of the trench of the hard mask 50 when the film forming process is performed is 2 or more.

[0088] Next, in the wafer W, using the hard mask 50 having a trench extended by the carbon-based film 51, the oxide layer 49 under the hard mask 50 is etched on the wafer W (FIG. 13(B)). As a result of the etching of the oxide layer 49, trenches with a high aspect ratio are formed in the oxide layer 49 corresponding to the extended trenches of the hard mask 50, but the carbon-based film 51 is removed and the hard mask 50 is also consumed (FIG. 13(B)).

[0089] Thereafter, the wafer W is subjected to ashing to completely remove the consumed hard mask 50 (FIG. 13(C)).

[0090] As described above, the preferred embodiments of the present disclosure have been described. However, the present disclosure is not limited to the above-described embodiments, and various modifications and changes are possible within the scope of the gist thereof.

[0091] For example, in the present embodiment, a carbon-based film is selectively formed on the top of the trench as a pattern, but a carbon-based film may be selectively formed on the top of the trench as a pattern.

[0092] In addition, in the present embodiment, hydrocarbon gas (acetylene gas) is used as the hydrogen compound gas to form a carbon-based film as the film selectively formed on the top of the pattern. However, other hydrogen compound gases, for example, silane gas which is a hydrogen compound gas of silicon or borane gas which is a hydrogen compound gas of boron, may be used instead of the hydrocarbon gas as the hydrogen compound gas.

[0093] When a film-forming gas composed only of silane gas, argon gas, and hydrogen gas is used and a film-forming process is performed on the wafer W using the film-forming apparatus 100, a silicon-based film that does not overhang toward the trench or hole can be selectively formed on the top of the pattern. Further, when a film-forming gas composed only of borane gas, argon gas, and hydrogen gas is used and a film-forming process is performed on the wafer W using the film-forming apparatus 100, a boron-based film that does not overhang toward the trench or hole can be selectively formed on the top of the pattern.

[0094] Furthermore, the film-forming apparatus that executes the carbon-based film-forming method according to the present embodiment is not limited to the film-forming apparatus 100 of FIG. 1.

[0095] FIG. 14 is a diagram showing a first modification of the film-forming apparatus that executes the carbon-based film-forming method according to the present embodiment. As shown in FIG. 14, the film-forming apparatus 101 has the same configuration as the film-forming apparatus 100, and is different from the film-forming apparatus 100 only in that one or more, for example, two electrode plates 221 and 222 are arranged between the upper electrode 20 and the mounting table 14 instead of the top plate 23 and the intermediate member 24.

[0096] In the film-forming apparatus 101, an insulating member 211 is interposed between the base member 22 and the electrode plate 221, and an insulating member 212 is interposed between the electrode plate 221 and the electrode plate 222. Thereby, the base member 22, the electrode plate 221, and the electrode plate 222 are electrically independent of each other. In the film-forming apparatus 101, the base member 22 functions as an upper electrode, and plasma is generated from the film-forming gas in the gas diffusion space 25.

[0097] In addition, a large number of through holes 231 and 232 are respectively provided in the electrode plate 221 and the electrode plate 222. Each through hole 231 and each through hole 232 are arranged such that their positions overlap when the electrode plates 221 and 222 are viewed from the mounting table 14 side. When the potentials of the electrode plate 221 and the electrode plate 222 are controlled, among the radicals and ions of the plasma generated in the gas diffusion space 25, the ions are accelerated. However, since the ions have strong anisotropy, they pass through the through holes 231 and 232 whose positions overlap. That is, the electrode plates 221 and 222 function as a kind of filter for selecting strongly anisotropic ions and supplying them to the wafer W.

[0098] Furthermore, by controlling the potentials of the electrode plate 221 and the electrode plate 222, it is also possible to reduce the energy of the passed ions and reduce the ion energy applied to the wafer W. At this time, for example, the electrode plate 222 is connected to the ground, and a negative voltage of -100 V is applied to the electrode plate 221. In the film forming apparatus 101, the high-frequency power supply 32 supplies high-frequency power with a frequency of 200 kHz to 460 MHz to the upper electrode 20.

[0099] FIG. 15 is a diagram showing a second modification of a film forming apparatus for executing a method for forming a carbon-based film according to the present embodiment. As shown in FIG. 15, the film forming apparatus 102 has the same configuration as the film forming apparatus 100, and is different from the film forming apparatus 100 only in that it further includes a second impedance circuit 36 (impedance adjusting means).

[0100] The second impedance circuit 36 is arranged in a second electrical path 38 that connects the wall portion of the chamber 11 and the ground. In addition, a current sensor 39 for measuring the current value flowing through the second electrical path 38 is arranged in the second electrical path 38. The second impedance circuit 36 includes a series circuit of a variable inductor and a variable capacitor, and can change the impedance between the wall portion of the chamber 11 and the ground.

[0101] In the film forming apparatus 102, the impedance of the first electrical path 37 is set to be higher than that of the second electrical path 38 by the first impedance circuit 35 and the second impedance circuit 36 controlled by the control unit 34. As a result, the electrical coupling between the upper electrode 20 and the lower electrode 17 is weakened and the current flowing through the lower electrode 17 is reduced, so that the ion energy of the plasma in the vicinity of the lower electrode 17 is reduced. As a result, the ion energy applied to the wafer W placed on the mounting table 14 is reduced.

[0102] Also, the carbon-based film forming method according to the present embodiment can be executed using the film forming apparatus 40 shown in FIG. 16(A).

[0103] Furthermore, the carbon-based film forming method according to the present embodiment can also be executed using the film forming apparatus 52 shown in a simplified manner in FIG. 16(B). The film forming apparatus 52 is a capacitively coupled plasma processing apparatus. The film forming apparatus 52 has two electrode plates 221 and 222 disposed between the upper electrode 20 and the mounting table 14, similar to the film forming apparatus 101. Then, similar to the film forming apparatus 101, ions can be selected from the generated plasma by controlling the potentials of the electrode plate 221 and the electrode plate 222.

[0104] Also, when controlling the potentials of the electrode plate 221 and the electrode plate 222, for example, in order to stabilize plasma generation, the electrode plate 222 is connected to the ground and a positive voltage is applied to the electrode plate 221. At this time, the positive ions in the plasma are accelerated by the potential difference between the electrode plate 221 to which the positive voltage is applied and the electrode plate 222 connected to the ground. That is, the positive ions in the plasma are adjusted to appropriate ion energy and supplied to the wafer W by changing the voltage value of the positive voltage applied to the electrode plate 221.

[0105] In the film forming apparatus 101, if there is at least one electrode plate disposed between the mounting table 14 and the upper electrode 20, the method for forming a carbon-based film according to the present embodiment can be executed. When the number of electrode plates is one, in order to reduce the plasma potential, it is desirable that the frequency of the high-frequency power supplied to the upper electrode 20 is 40 MHz or higher. When the number of electrode plates is two or more, since the potential difference in the region through which positive ions in the plasma pass can be finely adjusted, the controllability of the ion energy is improved. Therefore, the frequency of the high-frequency power applied to the upper electrode 20 can be set in a wide range, for example, from 200 kHz to 460 MHz.

[0106] As described above, even when using the film forming apparatus 52, the ion energy applied to the wafer W placed on the mounting table 14 can be reduced in the same manner as in the film forming apparatus 100. That is, also in the film forming apparatus 52, the film forming process executed in the film forming apparatus 100 can be reproduced.

[0107] Also, the method for forming a carbon-based film according to the present embodiment can be executed even when using the film forming apparatus 54 shown simplified in FIG. 16(C). The film forming apparatus 54 is a normal capacitively coupled plasma processing apparatus. In the film forming apparatus 52, inside the chamber 11, a conductive ring member 41 is disposed so as to surround the mounting table 14 (lower electrode 17). The ring member 41 is directly grounded, while the lower electrode 17 is grounded via the first impedance circuit 35. The first impedance circuit 35 imparts a high impedance to the first electrical path 37. Therefore, since the impedance of the first electrical path 37 becomes higher than the impedance of the third electrical path 42 connecting the ring member 41 and the ground, the ion energy applied to the wafer W placed on the mounting table 14 is reduced in the same manner as in the film forming apparatus 100. That is, the film forming process executed in the film forming apparatus 100 can be reproduced by the evaluation apparatus 40. The evaluation apparatus 40 does not include the second impedance circuit 36 and the second electrical path 38.

Explanation of Reference Numerals

[0108] W wafer 52,54,100,101,102 Film deposition equipment 11. Chamber 17 Lower electrode 20 Upper electrode 40 Evaluation Equipment 44 Oxide layer 44a Fin 45,48,51 Carbon-based membrane 47 Wiring layer 47a Metal protrusion 50 Hard Mask

Claims

1. A film forming step of forming a carbon-based film on a substrate having a pattern, In the film forming step, plasma is generated from a film forming gas composed only of a hydrocarbon gas, an argon gas, and a hydrogen gas, and the carbon-based film is selectively formed on the top of the pattern. A method for forming a carbon-based film.

2. The hydrocarbon gas is acetylene gas. The method for forming a carbon-based film according to claim 1.

3. In the film forming step, the temperature of the substrate is set to a temperature higher than 200°C. The method for forming a carbon-based film according to claim 1.

4. In the film forming step, the temperature of the substrate is set to a temperature of 300°C or higher. The method for forming a carbon-based film according to claim 3.

5. The addition rate of the hydrogen gas in the film forming gas is 3% or more. The method for forming a carbon-based film according to claim 1.

6. The pattern is either a trench or a hole. The method for forming a carbon-based film according to claim 1.

7. The aspect ratio of the trench and the hole is 2 or more. The method for forming a carbon-based film according to claim 6.

8. The aspect ratio of the trench and the hole is 4 or more. The method for forming a carbon-based film according to claim 7.

9. In the film forming step, the substrate is housed in a processing chamber whose interior is depressurized and placed on a mounting table disposed inside the processing chamber. Plasma is generated from the film forming gas inside the processing chamber, and the maximum value of the ion energy of the plasma is controlled to 200 eV or less. The method for forming a carbon-based film according to claim 1.

10. In the film forming step, the substrate is housed in a processing chamber whose interior is depressurized and placed on a mounting table disposed inside the processing chamber. Plasma is generated from the film forming gas inside the processing chamber, and a frequency of 40 MHz or higher is applied to an electrode facing the mounting table. The method for forming a carbon-based film according to claim 1.

11. In the film forming step, the substrate is housed in a processing chamber whose interior is depressurized and placed on a mounting table disposed inside the processing chamber. Plasma is generated from the film forming gas inside the processing chamber, At least one or more electrodes are disposed between the electrode facing the mounting table and the mounting table. The method for forming a carbon-based film according to claim 1.

12. In the film forming step, the substrate is housed in a processing chamber with a reduced internal pressure and placed on a mounting table disposed inside the processing chamber. Plasma is generated from the film forming gas inside the processing chamber, and the impedance between the mounting table and the ground is set higher than the impedance between the wall portion of the processing chamber and the ground. The method for forming a carbon-based film according to claim 1.

13. The pattern is a metal protrusion protruding from an interlayer insulating film, and the carbon-based film is selectively formed on the top of the metal protrusion. The method for forming a carbon-based film according to claim 1.

14. The pattern is a trench or a hole formed in a hard mask, and the carbon-based film is selectively formed on the top of the trench or the hole. The method for forming a carbon-based film according to claim 1.

15. After etching the lower layer of the hard mask using the hard mask, the carbon-based film is selectively formed on the top of the trench or the hole of the hard mask consumed by the etching. The method for forming a carbon-based film according to claim 14.

16. Before etching the lower layer of the hard mask using the hard mask, the carbon-based film is selectively formed on the top of the trench or the hole of the hard mask. The method for forming a carbon-based film according to claim 14.

17. Comprising a processing chamber with a reduced internal pressure, A film forming apparatus that houses a substrate having a pattern inside the processing chamber and generates plasma from a film forming gas consisting only of a hydrocarbon gas, an argon gas, and a hydrogen gas inside the processing chamber to selectively form a carbon-based film on the top of the pattern.

18. The film forming apparatus according to claim 17, characterized in that the maximum value of the ion energy of the plasma generated inside the processing chamber is controlled to 200 eV or less.

19. A mounting table for mounting the substrate, An electrode facing the mounting table, The film forming apparatus according to claim 17, further comprising a high-frequency power supply that supplies high-frequency power having a frequency of 40 MHz or more to the electrode.

20. A mounting table for mounting the substrate, An electrode facing the mounting table, The film forming apparatus according to claim 17, further comprising at least one or more electrodes disposed between the mounting table and the electrode.

21. A mounting table for mounting the substrate, The film forming apparatus according to claim 17, further comprising impedance adjusting means for setting the impedance between the mounting table and the ground to be higher than the impedance between the wall portion of the processing chamber and the ground.

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