Method and apparatus for forming carbon-based film

Abstract

The invention provides a method and a device for forming a carbon-based film, which can suppress the generation of overhang of the carbon-based film and improve productivity when the carbon-based film is selectively formed on the top of a pattern such as a trench or a hole. In the film forming apparatus, the temperature of the wafer (W) is at least higher than 200 DEG C, and the addition rate of hydrogen gas in a film forming gas comprising only acetylene gas, argon gas, and hydrogen gas is set to 3% or more, and the film forming process is performed.

Description

Technical Field

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

[0002] In semiconductor devices, in order to form wiring with more complex shapes and fine wiring, a technique of selectively forming a carbon-based film on the top of trenches and holes formed in a mask and 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 flowable film, which is an amorphous carbon polymer film, is mainly deposited on the bottom of the trench, and then the flowable film at the bottom is exposed to nitrogen plasma to etch the flowable film at the bottom, and gaseous C x N y H z species are formed. At this time, the adhesion coefficient of the C x N y H z species to the top of the trench exposing silicon is higher than the adhesion coefficient of the C x N y H z species to the flowable film at the bottom. Therefore, the C x N y H z species is selectively redeposited on the top of the trench. As a result, a carbon-based film is selectively formed on the top of the trench.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2021-19199 Summary of the Invention

[0006] Technical Problem to be Solved by the Invention

[0007] When the technique of the present invention selectively forms a carbon-based film on the top of patterns such as trenches and holes, the generation of overhang of the carbon-based film is suppressed, and the productivity is improved.

[0008] Technical Solution for Solving the Technical Problem

[0009] One aspect of the technique of the present invention 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, a plasma is generated from a film-forming gas composed only of a hydrocarbon gas, argon, and hydrogen to selectively form the carbon-based film on the top of the pattern.

[0010] Advantageous Effects of the Invention

[0011] According to the technology of the present invention, when selectively forming a carbon-based film on the top of patterns such as grooves and holes, the generation of overhangs of the carbon-based film can be suppressed, and the productivity can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a cross-sectional view schematically showing the structure of a film-forming apparatus as an embodiment of the technology of the present invention.

[0013] Figure 2 It is a diagram showing the film-forming morphology when the temperature of the wafer is changed during film-forming processing in an evaluation apparatus.

[0014] Figure 3 It is a diagram showing the film-forming morphology when the addition rate of hydrogen in the film-forming gas is changed during film-forming processing in an evaluation apparatus.

[0015] Figure 4 It is a diagram showing the film-forming morphology when the addition rate of hydrogen in the film-forming gas is changed during film-forming processing in an evaluation apparatus.

[0016] Figure 5 It is a diagram for explaining the influence of the temperature of the wafer and the addition rate of hydrogen in the film-forming gas on the film-forming morphology of the carbon-based film.

[0017] Figure 6 It is a diagram showing the film-forming morphology when the aspect ratio of the trenches of the oxide layer is changed in a wafer subjected to film-forming processing.

[0018] Figure 7 It is a diagram for explaining the influence of the aspect ratio of the trenches on the film-forming morphology of the carbon-based film.

[0019] Figure 8 It is a diagram showing the film-forming morphology when the ion energy of the plasma is changed in a wafer subjected to film-forming processing.

[0020] Figure 9 It is a diagram schematically showing the calculation results of the change in the angular distribution of the ion energy when the maximum value of the ion energy of the plasma used in the film-forming process is different.

[0021] Figure 10 It is a diagram showing the film-forming morphology when the configuration of the film-forming apparatus is changed in a wafer subjected to film-forming processing.

[0022] Figure 11 It is a step diagram showing an example of selectively forming a carbon-based film on the top of a metal protrusion which is a wiring layer protruding from an interlayer insulating film.

[0023] Figure 12 It is a step diagram showing an example of selectively forming a carbon-based film on the top of the trenches of a hard mask.

[0024] Figure 13 It is a process diagram showing another example of selectively forming a carbon-based film on the top of the trench of the hard mask.

[0025] Figure 14 It is a diagram showing a first modification example of a film forming apparatus for performing the film forming method of the carbon-based film of the present embodiment.

[0026] Figure 15 It is a diagram showing a second modification example of a film forming apparatus for performing the film forming method of the carbon-based film of the present embodiment.

[0027] Figure 16 It is a diagram showing other modification examples of a film forming apparatus for performing the film forming method of the carbon-based film of the present embodiment.

[0028] Description of Reference Numerals

[0029] W Wafer

[0030] 52, 54, 100, 101, 102 Film forming apparatus

[0031] 11 Chamber

[0032] 17 Lower electrode

[0033] 20 Upper electrode

[0034] 40 Evaluation device

[0035] 44 Oxide layer

[0036] 44a Fin

[0037] 45, 48, 51 Carbon-based film

[0038] 47 Wiring layer

[0039] 47a Metal protrusion

[0040] 50 Hard mask. Detailed Description of the Invention

[0041] However, in the technology described in Patent Document 1, after the fluid film is deposited on the bottom of the trench, the carbon-based film is re-deposited on the top of the trench by exposure to nitrogen plasma. Therefore, two steps are required to form the carbon-based film on the top of the trench, resulting in a reduction in productivity.

[0042] In addition, in the technology described in Patent Document 1, when the re-deposition of the carbon-based film on the top of the trench progresses, there is a possibility that a carbon-based film overhang is generated and the trench is blocked.

[0043] In this regard, the technology of the present invention suppresses the generation of overhangs of the carbon-based film when selectively forming the carbon-based film on the tops of patterns such as trenches and holes, and improves the productivity.

[0044] Hereinafter, with reference to the accompanying drawings, an embodiment of the technology of the present invention will be described. Figure 1 It is a cross-sectional view schematically showing the structure 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.

[0045] In Figure 1 it, the film-forming apparatus 100 has a substantially cylindrical chamber 11 (processing chamber) for accommodating a wafer W (substrate). In the chamber 11, as described later, plasma is generated from a film-forming gas inside. The chamber 11 has a loading / unloading port 12 for feeding the wafer W into and out of the inside on the side wall, and the loading / unloading port 12 is opened and closed by a gate 13.

[0046] A substantially disk-shaped mounting table 14 is disposed inside the chamber 11, and the mounting table 14 mounts the wafer W. In addition, an annular guide ring 15 is disposed at the outer edge portion 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.

[0047] And, a lower electrode 17, a heater 18, and a coolant passage (not shown) are embedded inside the mounting table 14. The heater 18 generates heat using the power supplied from a heater power supply 19 and heats the mounted wafer W. The coolant passage cools the mounted wafer W by circulating a coolant supplied from the outside. In addition, in order to improve the heat transfer performance between the mounting table 14 and the wafer W, a heat transfer gas is supplied between the mounting table 14 and the wafer W.

[0048] In addition, an upper electrode 20 is disposed at the top 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 has 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 such as aluminum. The top plate 23, the intermediate member 24, and the base member 22 are arranged in order from below, but the top plate 23 and the base member 22 are spaced apart by the substantially annular intermediate member 24 to form a gas diffusion space 25 therebetween. A gas inlet 26 communicating with the gas diffusion space 25 from above is provided through the base member 22. On the other hand, a plurality of air holes 27 for communicating the gas diffusion space 25 with the inside of the chamber 11 are provided through the top plate 23.

[0049] In addition, the film forming apparatus 100 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 includes a gas source, a flow controller, and an opening / closing valve, and supplies a plasma-treated processing gas, such as a film forming gas. The supplied film forming gas is introduced into the gas diffusion space 25 through the gas introduction port 26, and then diffuses into the interior of the chamber 11 from each air hole 27 and is introduced therein. Thus, the upper electrode 20 functions as a shower head. A heat insulating member 30 is disposed on the upper electrode 20. In addition, in the present embodiment, the film forming gas supplied by the gas supply unit 28 is composed only of acetylene gas (hydrocarbon gas), argon gas, and hydrogen gas.

[0050] The film forming apparatus 100 further includes an exhaust device 31, and the exhaust device 31 is composed of, for example, a turbo molecular pump or a dry pump. The exhaust device 31 decompresses the interior of the chamber 11 via an exhaust pipe 31a connected to the bottom of the chamber 11.

[0051] 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 matcher 33. The matcher 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.

[0052] Therefore, in the film forming apparatus 100, high-frequency power with a frequency of 40 MHz or more is supplied to the upper electrode 20. Generally, when generating plasma by supplying high-frequency power with a frequency of 40 MHz or more to the upper electrode 20, the generated plasma becomes high-density plasma, and the 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 that in the case of supplying a low-frequency voltage (frequency: 200 kHz to 13 MHz). That is, when supplying high-frequency power to the upper electrode 20, the plasma potential decreases, and thus the sheath voltage that contributes to the acceleration of ions in the plasma decreases. In addition, the higher the applied voltage, the faster the sheath vibrates, so the followability of ions to the sheath voltage decreases. As a result, the ion energy imparted to the wafer W placed on the stage 14 from the plasma decreases.

[0053] 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 having a processor, a memory, an input device, a display device, an input / output interface for signals, etc. A control program and recipe data are stored in the memory of the control unit 34. In the film forming apparatus 100, when performing 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.

[0054] 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. In addition, the control unit 34 controls the gas supply unit 28 to diffuse and introduce the film-forming gas into the interior of 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 to generate plasma, and the film-forming process is performed on the wafer W using this plasma.

[0055] The film-forming apparatus 100 further includes a first impedance circuit 35. The first impedance circuit 35 is disposed on a first electrical path 37 that connects the lower electrode 17 to the ground wire. The first impedance circuit 35 includes at least one of an inductor and a capacitor, and by connecting them in series or in parallel, the impedance between the lower electrode 17 and the ground wire can be changed. In addition, the inductor and capacitor included in the first impedance circuit 35 can be either fixed elements or variable elements.

[0056] It is also possible to control the impedance to be changed to weaken the electrical coupling between the upper electrode 20 and the lower electrode 17 and further reduce the high-frequency current flowing in the lower electrode 17. As a result, the energy value of the ions incident on the wafer W can be controlled more precisely.

[0057] In addition, the applicant of the present invention uses an evaluation apparatus 40 having a structure similar to that of the Figure 1 film-forming apparatus 100, changes the temperature of the wafer W and the addition rate of hydrogen in the film-forming gas to perform a film-forming process on the wafer W, and confirms the film-forming morphology of the carbon-based film on the wafer W. In addition, the temperature of the wafer W in the present embodiment is actually the temperature of the stage 14 on which the wafer W is placed.

[0058] The structure of the evaluation apparatus 40 is schematically shown in Figure 16 (A) below, and the structure other than that shown in the figure is the same as that 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 impedance of the plasma decreases. As a result, the voltage amplitude Vpp in 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 a high speed, the followability of the ions to the sheath voltage decreases. As a result, similar to the film-forming apparatus 100, the ion energy imparted to the wafer W placed on the stage 14 decreases. That is, the film-forming process in the film-forming apparatus 100 can be reproduced using the evaluation apparatus 40.

[0059] Figure 2It is a diagram showing the film formation morphology when the temperature of the wafer W is changed during the film formation process in the evaluation apparatus 40. In Figure 2 a magnified cross-section of the oxide layer 44 formed on the surface of the wafer W with a silicon substrate 43 and having a plurality of grooves as patterns is shown. Further, the oxide layer 44 is a base layer of the carbon-based film 45 to be formed.

[0060] At this time, the present applicant set the addition rate of acetylene gas in the film formation 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). Further, the addition rate of each gas in the present embodiment is the flow rate ratio of each gas to the total gas flow rate of the film formation gas. Then, the pressure inside the chamber 11 was set to 1 Torr, and high-frequency power with a frequency of 40 MHz was supplied to the upper electrode 20 at 500 W from the high-frequency power supply 32, and plasma was generated from the film formation gas to perform a film formation process on the wafer W. In addition, the temperature of the wafer W was set to 200°C and 400°C.

[0061] Figure 2 (A) shows the film formation morphology of the carbon-based film 45 when the temperature of the wafer W is set to 200°C for film formation, Figure 2 (B) shows the film formation morphology of the carbon-based film 45 when the temperature of the wafer W is set to 400°C for film formation.

[0062] First, it was confirmed that when the temperature of the wafer W was set to 200°C, on the top of the fin 44a (corresponding to the top of the groove) sandwiched by each groove of the oxide layer 44, the carbon-based film 45 was formed in a protruding manner so as to block the groove. In addition, it was confirmed that the carbon-based film 45 was also formed inside the groove. That is, it was confirmed that an inappropriate carbon-based film 45 was formed as the carbon-based film that should be selectively formed on the top of the fin 44a. On the other hand, it was confirmed that when the temperature of the wafer W was set to 400°C, the carbon-based film 45 was formed only on the top of the fin 44a, the carbon-based film 45 did not protrude toward the groove, and the carbon-based film 45 was hardly formed inside the groove. That is, it was confirmed that a suitable carbon-based film 45 was formed as the carbon-based film that should be selectively formed on the top of the fin 44a.

[0063] And, without changing the flow rates of acetylene gas and argon gas in the film formation gas, the present applicant changed the addition rate of hydrogen gas to 10% (flow rate: 100 sccm) and set the temperature of the wafer W to 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 as shown in Figure 2 (C).

[0064] It was confirmed that when the temperature of the wafer W was set to 300 °C, the carbon-based film 45 was formed only on the top of the fin portion 44a, the carbon-based film 45 did not protrude toward the trench, and the carbon-based film 45 was hardly formed inside the trench. That is, similarly to when the temperature of the wafer W was set to 400 °C, it was confirmed that a suitable carbon-based film 45 was formed as the carbon-based film that should be selectively formed on the top of the fin portion 44a.

[0065] Figure 3 It is a diagram showing the film formation morphology when the addition rate of hydrogen in the film formation gas is changed during the film formation process in the evaluation apparatus 40. In Figure 3 also, similarly to Figure 2 it shows an enlarged cross-sectional view of the oxide layer 44 having a plurality of trenches formed on the surface of the wafer W.

[0066] 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. In addition, high-frequency power 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 the acetylene gas in the film formation gas was set to 30 sccm, the flow rate of the argon gas was set to 1000 sccm, and the addition rate of hydrogen in the film formation gas was set to 1.7% and 3%.

[0067] Figure 3 (A) of Figure 3 shows the film formation morphology of the carbon-based film 45 when the film formation process was performed with the hydrogen addition rate set to 1.7%,

[0068] First, it was confirmed that when the hydrogen addition rate was set to 1.7%, although the carbon-based film 45 was formed only on the top of the fin portion 44a, the carbon-based film 45 bulged laterally and protruded toward the trench. That is, it was confirmed that an unsuitable carbon-based film 45 was formed as the carbon-based film that should be selectively formed on the top of the fin portion 44a. On the other hand, it was confirmed that when the hydrogen addition rate was set to 3%, the carbon-based film 45 was formed only on the top of the fin portion 44a, the carbon-based film 45 did not protrude toward the trench, and the carbon-based film 45 was hardly formed inside the trench. That is, it was confirmed that a suitable carbon-based film 45 was formed as the carbon-based film that should be selectively formed on the top of the fin portion 44a.

[0069] Figure 4 also, similarly to Figure 3 it is a diagram showing the film formation morphology when the addition rate of hydrogen in the film formation gas is changed during the film formation process in the evaluation apparatus 40.

[0070] At this time, the applicant set the pressure inside the chamber 11 to 1 Torr and the temperature of the wafer W to 350°C. In addition, high-frequency power of 40 MHz was supplied to the upper electrode 20 at 500 W from the high-frequency power supply 32, 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).

[0071] Figure 4 (A) of Figure 4 is the film-forming morphology of the carbon-based film 45 when the addition rate of hydrogen gas is set to 2% for film-forming treatment. Figure 4 (B) of Figure 4 is the film-forming morphology of the carbon-based film 45 when the addition rate of hydrogen gas is set to 4% for film-forming treatment.

[0072] First, it was confirmed that when the addition rate of hydrogen gas was set to 2%, similar to 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 portion 44a, the carbon-based film 45 bulged laterally and protruded toward the trench. That is, it was confirmed that an inappropriate carbon-based film 45 was formed as the carbon-based film that should be selectively formed at the top of the fin portion 44a. On the other hand, it was confirmed that when the addition rate of hydrogen gas was set to 4%, the carbon-based film 45 was formed only at the top of the fin portion 44a, and the carbon-based film 45 did not protrude toward the trench, and the carbon-based film 45 was hardly formed inside the trench. That is, it was confirmed that a suitable carbon-based film 45 was formed as the carbon-based film that should be selectively formed at the top of the fin portion 44a.

[0073] According to Figures 2 to 4 the confirmation results shown in Figures 2 to 4 , there is a phenomenon that the higher the temperature of the wafer W and the higher the addition rate of hydrogen gas, the smaller the protrusion of the carbon-based film 45 formed at the top of the fin portion 44a, and the less likely the carbon-based film 45 is to be formed inside the trench. As the reason for such a phenomenon, the applicant speculates the mechanism described below.

[0074] Figure 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 morphology of the carbon-based film 45.

[0075] First, explain Figure 5 the film-forming morphology in the case where the temperature of the wafer W is low and the addition rate of hydrogen gas is low, as shown in (A) of Figure 5 .

[0076] However, the plasma generated from the acetylene gas that is the main factor for forming the carbon-based film 45 contains hydrocarbon ions and hydrocarbon radicals, but the hydrocarbon ions have strong anisotropy and adhere to the fin-shaped portion 44a of the oxide layer 44 approximately vertically. On the other hand, the hydrocarbon radicals have strong isotropy and adhere to the fin-shaped portion 44a of the oxide layer 44 from all directions.

[0077] Furthermore, when the temperature of the wafer W is low, the temperature of the atmosphere near the wafer W also becomes low, but when the atmosphere temperature is low, the probability of hydrocarbon radicals and hydrocarbon ions attaching is still high. Therefore, hydrocarbon ions are mainly accumulated vertically on the top of the fin-shaped portion 44a, and hydrocarbon radicals are accumulated not only on the top of the fin-shaped portion 44a, but also on the side of the fin-shaped portion 44a and the bottom of the groove. In addition, for easy understanding, Figure 5 In (A), the carbon film derived from hydrocarbon ions is indicated by reference numeral 45a, and the carbon film derived from hydrocarbon radicals is indicated by reference numeral 45b. However, in reality, the carbon film derived from hydrocarbon ions and the carbon film derived from hydrocarbon radicals are mixed to form the carbon film 45.

[0078] The carbon film 45 is isotropically etched by hydrogen radicals contained in hydrogen plasma generated from hydrogen gas, but when the ambient temperature is low, the etching force of the hydrogen radicals is weak and the carbon film 45 is hardly etched. In the figure, the length of the arrow schematically indicates the magnitude of the etching force.

[0079] As a result, the carbon film 45 grows on the side and top of the fin 44a and the bottom of the groove when the temperature of the wafer W is low. In particular, on the top of the fin 44a, not only the carbon film 45b derived from hydrocarbon radicals but also the carbon film 45a derived from hydrocarbon ions grows significantly, so the carbon film 45 grows significantly and overhangs toward the groove.

[0080] Next, explain Figure 5 FIG. 1 shows the film formation state when the temperature of the wafer W is high and the addition rate of hydrogen gas is high, as shown in FIG. 1 (B).

[0081] When the temperature of the wafer W is high, the temperature of the atmosphere near the wafer W also becomes high. However, when the atmosphere temperature is high, although the probability of hydrocarbon ion attachment is still high, the probability of hydrocarbon radical attachment is reduced. Therefore, hydrocarbon ions are vertically accumulated on the top of the fin-shaped portion 44a, but the degree of accumulation of hydrocarbon radicals on the side of the fin-shaped portion 44a and the bottom of the groove is reduced. That is, the carbon film 45a derived from hydrocarbon ions formed on the top of the fin-shaped portion 44a has the same thickness as when the temperature of the wafer W is low. However, compared with the case where the temperature of the wafer W is low, the carbon film 45b derived from hydrocarbon radicals formed on the side of the fin-shaped portion 44a and the bottom of the groove becomes very thin ( Figure 5(B) of

[0082] In addition, when the ambient temperature is high, the etching force of hydrogen radicals increases, and the carbon-based film 45 is etched isotropically. Thus, inside the trench, the thin carbon-based film 45b from hydrocarbon radicals is removed by etching, and it is difficult to form the carbon-based film 45 inside the trench. Moreover, on the top of the fin portion 44a, the thin carbon-based film 45b from hydrocarbon radicals is also removed by etching, and only the thick carbon-based film 45a from carbon hydride ions remains. As a result, the growth of the carbon-based film 45 is inhibited to some extent and does not overhang toward the trench.

[0083] In addition, the present applicant used the evaluation device 40 to perform a film formation process on the wafer W by changing the aspect ratio (aspect ratio) of the trenches of the oxide layer 44, and confirmed the film formation morphology of the carbon-based film on the wafer W. Figure 6 It is a diagram showing the film formation morphology when the aspect ratio of the trenches of the oxide layer 44 is changed in the wafer W on which the film formation process is performed. In Figure 6 it also shows, in the same way as Figure 2 an enlarged cross section of the oxide layer 44.

[0084] At this time, the present applicant set the pressure inside the chamber 11 to 1 Torr and the temperature of the wafer W to 370 °C. In addition, high-frequency power with a frequency of 40 MHz was supplied to the upper electrode 20 at 500 W from the high-frequency power supply 32, and plasma was generated from the film formation gas to perform a film formation process on the wafer W. Then, the addition rate of acetylene gas in the film formation 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).

[0085] Figure 6 (A) shows the film formation morphology of the carbon-based film 45 when the film formation process is performed on the wafer W with the aspect ratio of the trenches of the oxide layer 44 set to 4. Figure 6 (B) shows the film formation morphology of the carbon-based film 45 when the film formation process is performed on the wafer W with the aspect ratio of the trenches of the oxide layer 44 set to 2.

[0086] First, it was confirmed that in the wafer W with the aspect ratio of the trench set to 4, the carbon-based film 45 was formed only on the top of the fin portion 44a, the carbon-based film 45 did not overhang toward the trench, and the carbon-based film 45 was hardly formed inside the trench. That is, it was confirmed that a suitable carbon-based film 45 was formed as the carbon-based film that should be selectively formed on the top of the fin portion 44a. In addition, in the wafer W with the aspect ratio of the trench set to 2, the carbon-based film 45 was formed not only on the top of the fin portion 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 only by slightly performing ashing later. Moreover, the carbon-based film 45 on the top of the fin portion 44a did not overhang toward the trench. Therefore, it was confirmed that a substantially suitable carbon-based film 45 was formed as the carbon-based film that should be selectively formed on the top of the fin portion 44a.

[0087] According to Figure 6 the confirmation results shown, when the aspect ratio of the trench of the oxide layer 44 is 2 or more, a substantially suitable carbon-based film 45 is formed as the carbon-based film that should be selectively formed on the top of the fin portion 44a. On the other hand, it is known that when the aspect ratio of the trench is high, there is a phenomenon that it is difficult to form the carbon-based film 45 inside the trench. As the reason for such a phenomenon, the present applicant speculates the mechanism described below.

[0088] Figure 7 It is a diagram for explaining the influence of the aspect ratio of the trench on the film formation morphology of the carbon-based film 45. In Figure 7 it, the hydrocarbon ions are represented by "○" and the hydrocarbon radicals are represented by "●".

[0089] As described above, the carbon-based film 45 inside the trench is mainly formed by the attachment of hydrocarbon radicals with strong isotropy. Moreover, as the hydrocarbon radicals, there are also hydrocarbon radicals that are incident obliquely to the trench. Here, as shown in (A) of Figure 7 , when the aspect ratio of the trench is low, the opening of the trench expands, and the hydrocarbon radicals incident obliquely to the trench easily enter the trench and attach to the side wall of the fin portion 44a and the bottom of the trench. Therefore, when the aspect ratio is low, there is a tendency that the carbon-based film 45 is also easily formed inside the trench.

[0090] On the other hand, as Figure 7As shown in (B), when the aspect ratio of the trench is high, the opening of the trench becomes narrow, and hydrocarbon radicals incident obliquely with respect to the trench are blocked by the top of the fin portion 44a (shielding effect). In addition, even if the hydrocarbon radicals enter the trench and adhere to the side wall of the fin portion 44a, since the area of the side wall of the fin portion 44a increases, the adhesion density of the hydrocarbon radicals decreases and it is difficult to form a thick carbon-based film 45 on the side wall of the fin portion 44a. Furthermore, the probability that the hydrocarbon radicals adhere to the side wall of the fin portion 44a before reaching the bottom of the trench also increases. Therefore, it is difficult for the hydrocarbon radicals to reach the bottom of the trench, and it is also not easy to form a thick carbon-based film 45 at the bottom of the trench. Therefore, when the aspect ratio is high, there is a tendency that it is difficult to form the carbon-based film 45 inside the trench.

[0091] In addition, the present applicant used the evaluation device 40 to change the ion energy of the plasma generated when the film formation process was performed on the wafer W having the trench with the aspect ratio (height-width ratio) of 4 formed thereon, and confirmed the film formation morphology of the carbon-based film on the wafer W. Figure 8 It is a diagram showing the film formation morphology when the ion energy of the plasma is changed in the wafer on which the film formation process is performed. In Figure 8 also, similarly to Figure 2 it shows an enlarged cross section of the oxide layer 44.

[0092] At this time, the present applicant set the pressure inside the chamber 11 to 1 Torr and the temperature of the wafer W to 370 °C. In addition, in order to change the ion energy of the plasma, high-frequency power with a frequency of 40 MHz was supplied to the upper electrode 20 from the high-frequency power supply 32 at 500 W, 1 kW, or 2 kW, and the film formation process was performed on the wafer W by generating plasma from the film formation gas. Then, the addition rate of acetylene gas in the film formation 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).

[0093] Furthermore, during the above film formation process, the present applicant 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, using the ion energy detector. 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.

[0094] Figure 8 (A) is the film formation 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 becomes 100 eV. Figure 8 (B) is the film formation 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 becomes 200 eV.Figure 8 The film formation state of carbon-based film 45 under the condition that (C) supplies high-frequency power of 1.5 kW at a frequency of 40 MHz and the maximum value of ion energy becomes 300 eV.

[0095] First, as shown in (A) of Figure 8 , it was confirmed that under the condition that the maximum value of ion energy becomes 100 eV, the carbon-based film 45 is formed only on the top of the fin portion 44a, the carbon-based film 45 does not protrude toward the groove, and the carbon-based film 45 is hardly formed inside the groove. That is, it was confirmed that a suitable carbon-based film 45 was formed as a carbon-based film that should be selectively formed on the top of the fin portion 44a.

[0096] In addition, as shown in (B) of Figure 8 , under the condition that the maximum value of ion energy becomes 200 eV, the carbon-based film 45 is formed not only on the top of the fin portion 44a but also at the bottom of the groove. However, the carbon-based film 45 at the bottom of the groove is very thin and is a film that can be removed only by slightly performing ashing later. Moreover, the carbon-based film 45 on the top of the fin portion 44a does not protrude toward the groove. Therefore, it was confirmed that a substantially suitable carbon-based film 45 was formed as a carbon-based film that should be selectively formed on the top of the fin portion 44a.

[0097] On the other hand, as shown in (C) of Figure 8 , under the condition that the maximum value of ion energy becomes 300 eV, the carbon-based film 45 is formed more on the top of the fin portion 44a. Although the carbon-based film 45 on the top of the fin portion 44a does not protrude toward the groove, the carbon-based film 45 is also formed at the bottom of the groove. Moreover, the carbon-based film 45 at the bottom of the groove has a certain thickness and is a film that cannot be removed only by slightly performing ashing later.

[0098] That is, according to the confirmation results shown in Figure 8 , when the maximum value of the ion energy of the plasma used for film formation processing becomes 200 eV or less, the carbon-based film 45 is hardly formed at the bottom of the groove, and the carbon-based film 45 can be selectively formed on the top of the fin portion 44a. On the other hand, it is known that when the maximum value of the ion energy of the plasma used in the film formation processing becomes 300 eV or more, the carbon-based film 45 with a certain thickness is formed at the bottom of the groove, and it is difficult to selectively form the carbon-based film 45 on the top of the fin portion 44a.

[0099] The applicant of the present invention qualitatively investigated the reason why the formation of the carbon-based film at the bottom of the groove can be suppressed by reducing the maximum value of the ion energy of the plasma through plasma state calculation. Figure 9 It is a diagram schematically showing the calculation results of the angular distribution of ion energy when the maximum value of the ion energy of the plasma used in the film formation processing is different. Figure 9In (A), the maximum value of the ion energy is 100 eV. Figure 9 In (B), the maximum value of the ion energy is 300 eV. Additionally, Figure 9 The arrows in [figure] indicate the magnitude of the proportion of ions at that angle.

[0100] The present applicant calculated (simulated) the plasma state under the film-forming conditions for achieving the specified shape of the carbon-based film 45. According to the calculation results at this time, when the maximum value of the ion energy of the plasma is increased, due to the increase in ion energy, the angular distribution of the ion energy changes. Specifically, it can be seen that when the maximum value of the ion energy is low, for example, 100 eV, the angular distribution of the ion energy is larger (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 is difficult to generate a difference between the proportions of ions at each angle ( Figure 9 In (A)). On the other hand, when the maximum value of the ion energy is 300 eV, the angular distribution of the ion energy becomes smaller (narrower range), a difference is generated between the proportions of ions at each angle, and in particular, the proportion of ions at an angle perpendicular to the wafer W increases ( Figure 9 In (B)).

[0101] Based on the above calculation results, the present applicant speculates that the reason for being able to suppress the formation of the carbon-based film at the bottom of the trench by reducing the maximum value of the ion energy of the plasma is as follows. That is, when the maximum value of the ion energy is reduced and the angular distribution of the ion energy becomes larger, the proportion of ions at an angle incident obliquely to the wafer W increases. Then, compared with the case where the maximum value of the ion energy is high, the proportion of ions at an angle perpendicular to the wafer W direction relatively decreases. Moreover, there is a certain distance from the plasma high-density region 53 to the wafer W, and ions other than those at an angle in the direction completely perpendicular to the wafer W are difficult to reach the bottom of the trench. As a result, the formation of the carbon-based film 45 at the bottom of the trench is suppressed.

[0102] In addition, the ions that contribute to film formation on the side surface of the trench are ions at an angle perpendicular or close to perpendicular to the wafer W. When the maximum value of the ion energy of the plasma is reduced and the angular distribution of the ion energy becomes larger, such ions decrease. That is, when the maximum value of the ion energy of the plasma is reduced, the formation of the carbon-based film 45 on the side surface of the trench can also be suppressed. At this time, it is also known that when the temperature of the wafer W is high, in combination with the increase in the etching force of hydrogen radicals, a phenomenon occurs in which the carbon-based film 45 is formed only on the top of the fin portion 44a.

[0103] Furthermore, in order to investigate suitable forms for implementing the technology of the present invention, the applicant performed a film formation process on the wafer W using film formation apparatuses with different configurations. In addition, regarding the film formation apparatuses used at this time, their structures were simplified and shown in Figure 16 below.

[0104] In each film formation apparatus, the applicant set the temperature of the wafer W to 400 °C. Additionally, although the addition rate of acetylene gas in the film formation gas differed depending on the film formation apparatus, in any film formation apparatus, it was adjusted to at least 3% or more (flow rate of 30 sccm or more). Furthermore, the other components of the film formation gas were argon and hydrogen, and the flow rate of argon was set to 1000 sccm.

[0105] Figure 10 (A) of Figure 16 is a diagram showing the film formation morphology when a film formation process is performed on the wafer W using the film formation apparatus (evaluation apparatus) 40 shown in (A) of Figure 10 (B) of Figure 16 is a diagram showing the film formation morphology when a film formation process is performed on the wafer W using the film formation apparatus 52 shown in (B) of Figure 10 (C) of Figure 16 is a diagram showing the film formation morphology when a film formation process is performed on the wafer W using the film formation apparatus 54 shown in (C) of

[0106] In addition, at this time, when the applicant performed the film formation process in each film formation apparatus, it was confirmed using an ion energy detector that the maximum value of the ion energy of the plasma became 200 eV or less. Moreover, the applicant observed Figure 10 (A) of Figure 10 (B) of Figure 10 (C) of Figure 10When forming the carbon-based film 45 in the film-forming pattern shown in (B), it was confirmed that a thin carbon-based film 45 was formed on the side surface of the trench. However, this carbon-based film 45 was very thin and was a film that could be removed only by slightly performing ashing later. That is, it was confirmed that in the film-forming apparatuses 40, 52, and 54, a substantially suitable carbon-based film 45 was formed as the carbon-based film that should be selectively formed on the top of the fin portion 44a.

[0107] As described above, it can be seen that in the present embodiment, in order to selectively form a suitable carbon-based film 45 on the top of the fin portion 44a, it is necessary to set the temperature of the wafer W to at least higher than 200°C, preferably 300°C or higher. In addition, it can be seen that the addition rate of hydrogen in the film-forming gas composed of only acetylene gas, argon gas, and hydrogen gas needs to be set to 3% or more. Furthermore, it can be seen that the aspect ratio of the trench of the base layer on which the carbon-based film 45 is formed needs to be set to 2 or more, preferably 4 or more. In addition, it can be seen that it is more preferably necessary to control the maximum value of the ion energy of the plasma used for the film-forming process to 200 eV or less.

[0108] In addition, according to the present embodiment, in the film-forming apparatus 100, the temperature of the wafer W is set to at least higher than 200°C, and the addition rate of hydrogen in the film-forming gas is set to 3% or more to perform the film-forming process. Thereby, a suitable carbon-based film 45 can be selectively formed on the top of the fin portion 44a of the oxide layer 44 in one step. That is, when selectively forming the carbon-based film 45 on the top of the trench, the generation of the overhang of the carbon-based film 45 can be suppressed, and the productivity can be improved.

[0109] Next, an application example of the film-forming method of the carbon-based film of the present embodiment will be described. As described above, the film-forming method of the carbon-based film of the present embodiment utilizes the change in the attachment probability of hydrocarbon radicals caused by temperature and the change in the etching force of hydrogen radicals caused by temperature. Therefore, the base of the carbon-based film does not affect the film formation of the carbon-based film. Therefore, the film-forming method of the carbon-based film of the present embodiment can be applied not only to the insulating film and mask whose base is composed of an oxide, but also to the wiring layer whose base is composed of a metal.

[0110] Figure 11 is a step diagram showing an example of selectively forming a carbon-based film on the top of a metal protrusion portion that is a wiring layer protruding from an interlayer insulating film. In Figure 11 , first, in the wafer W, metal is buried in each trench of the 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 ( Figure 11 (A)).

[0111] Next, ashing is performed on the wafer W to selectively remove the interlayer insulating film 46, creating 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, forming a metal protrusion 47a ( Figure 11 of (B)).

[0112] After that, in the film forming apparatus 100, the wafer W is housed inside the chamber 11 and placed on the placement table 14, and the evacuation device 31 decompresses the inside of the chamber 11. At this time, the heater 18 heats the placement table 14 and sets the temperature of the placement table 14 to a temperature higher than 200°C. Further, the gas supply unit 28 supplies a film forming gas composed only of acetylene gas, argon gas, and hydrogen gas via the upper electrode 20. The addition rate of hydrogen gas in the supplied film forming gas is set to 3% or more. In addition, the 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 a film forming process is performed on the wafer W to selectively form a carbon-based film 48 on the top of the metal protrusion 47a of the wiring layer 47 ( Figure 11 of (C)) (film forming step).

[0113] Next, a film forming process for an insulating film is performed on the wafer W to grow the interlayer insulating film 46 to fill the recessed shape. At this time, the upper surface of the interlayer insulating film 46 and the upper surface of the carbon-based film 48 are also planarized by CMP or the like ( Figure 11 of (D)).

[0114] After that, ashing is performed on the wafer W to completely remove the carbon-based film 48. At this time, the upper part of the interlayer insulating film 46 is also removed at the same time, but since the etching rate of the carbon-based film 48 is higher than the etching rate of the interlayer insulating film 46, a recessed shape in which the wiring layer 47 is recessed is generated ( Figure 11 of (E)).

[0115] Next, a via hole 47b is formed by re-forming the interlayer insulating film 46 and adding a part of the wiring layer 47 ( Figure 11 of (F)). At this time, by re-forming the interlayer insulating film 46, the distance L between the via hole 47b and the wiring layer 47 adjacent to the via hole 47b is sufficiently ensured.

[0116] Figure 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 Figure 12 , first, using a hard mask 50 having a plurality of trenches, etching of the oxide layer 49, which is the lower layer of the hard mask 50, is performed on the wafer W ( Figure 12 of (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 is also consumed ( Figure 12 of (B)).

[0117] Next, in the film forming apparatus 100, a film forming process is performed on the wafer W under the same conditions as in the Figure 11 example. At this time, a carbon-based film 51 is selectively formed on the top of the trench of the consumed hard mask 50, and the carbon-based film 51 extends the trench of the consumed hard mask 50 ( Figure 12 (C) of). In addition, the aspect ratio of the trench of the oxide layer 49 during the film forming process is 2 or more.

[0118] Next, an etching process is performed on the oxide layer 49 of 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. In addition, during the etching of the oxide layer 49, the consumption of the carbon-based film 51 progresses, and only a very small part of the carbon-based film 51 remains ( Figure 12 (D) of).

[0119] After that, ashing is performed on the wafer W to completely remove the remaining carbon-based film 51 and the consumed hard mask 50 ( Figure 12 (E) of). Thus, a trench with a high aspect ratio can be formed in the oxide layer 49.

[0120] Figure 13 is a process chart showing another example of selectively forming a carbon-based film on the top of the trench of the hard mask. In Figure 13 first, in the film forming apparatus 100, a film forming process is performed on the wafer W having the hard mask 50 with a plurality of trenches formed thereon under the same conditions as in the Figure 11 example. 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 ( Figure 13 (A) of). In addition, the aspect ratio of the trench of the hard mask 50 during the film forming process is 2 or more.

[0121] Next, in the wafer W, using the hard mask 50 having a trench extended by the carbon-based film 51, an etching process is performed on the oxide layer 49, which is the lower layer of the hard mask 50, of the wafer W ( Figure 13 (B) of). As a result of the etching of the oxide layer 49, a trench with a high aspect ratio is formed in the oxide layer 49 corresponding to the extended trench of the hard mask 50, but the carbon-based film 51 is removed and the hard mask 50 is also consumed ( Figure 13 (C) of).

[0122] After that, ashing is performed on the wafer W to completely remove the consumed hard mask 50 ( Figure 13 (D) of).

[0123] As described above, the preferred embodiments of the present invention have been described, but the present invention is not limited to the above-described embodiments, and various modifications and changes can be made within the scope of its gist.

[0124] For example, in the present embodiment, a carbon-based film is selectively formed on the top of the groove as a pattern, but a carbon-based film may also be selectively formed on the top of the hole as a pattern.

[0125] In addition, in the present embodiment, a hydrocarbon gas (acetylene gas) is used as the hydrocarbon gas to form a carbon-based film as a film selectively formed on the top of the pattern. However, as the hydrocarbon gas, other hydrocarbon gases may be used, for example, silane gas as a silicon-based hydrocarbon gas and borane gas as a boron-based hydrocarbon gas may be used instead of the hydrocarbon gas.

[0126] 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 groove or hole can be selectively formed on the top of the pattern. In addition, 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 groove or hole can be selectively formed on the top of the pattern.

[0127] Moreover, the film-forming apparatus for performing the film-forming method of the carbon-based film of the present embodiment is not limited to Figure 1 the film-forming apparatus 100.

[0128] Figure 14 FIG. is a diagram showing a first modification of the film-forming apparatus for performing the film-forming method of the carbon-based film of the present embodiment. As Figure 14 shown, the film-forming apparatus 101 has the same structure as the film-forming apparatus 100, and the difference from the film-forming apparatus 100 is only 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.

[0129] 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, whereby 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.

[0130] In addition, a plurality of through holes 231 and 232 are respectively provided in the electrode plate 221 and the electrode plate 222. When observing the electrode plate 221 and the electrode plate 222 from the side of the mounting table 14, the positions of the respective through holes 231 and the respective through holes 232 are arranged to overlap. And when the potentials of the electrode plate 221 and the electrode plate 222 are controlled, the ions among the free radicals and ions of the plasma generated in the gas diffusion space 25 are accelerated, but due to the strong anisotropy of the ions, they pass through the overlapping through holes 231 and 232. That is, the electrode plate 221 and the electrode plate 222 function as a kind of filter for screening ions with strong anisotropy and supplying them to the wafer W.

[0131] Moreover, by controlling the potentials of the electrode plate 221 and the electrode plate 222, the energy of the passing ions can also be reduced, and the ion energy imparted to the wafer W can be reduced. At this time, for example, the electrode plate 222 is grounded, and a negative voltage of -100V is applied to the electrode plate 221. In addition, 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.

[0132] Figure 15 It is a diagram showing a second modification of the film forming apparatus for performing the film forming method of the carbon-based film of the present embodiment. As Figure 15 shown, the film forming apparatus 102 has the same structure as the film forming apparatus 100, and the difference from the film forming apparatus 100 is only that it further has a second impedance circuit 36 (impedance adjustment unit).

[0133] The second impedance circuit 36 is disposed in a second electrical path 38 that connects the wall portion of the chamber 11 to the ground wire. In addition, a current sensor 39 for measuring the current value flowing in the second electrical path 38 is disposed 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 wire.

[0134] In the film forming apparatus 102, by using the first impedance circuit 35 and the second impedance circuit 36 controlled by the control unit 34, the impedance of the first electrical path 37 is set higher than the impedance of the second electrical path 38. As a result, the electrical coupling between the upper electrode 20 and the lower electrode 17 is weakened, the current flowing in the lower electrode 17 is reduced, and thus the ion energy of the plasma near the lower electrode 17 is reduced. As a result, the ion energy imparted to the wafer W placed on the mounting table 14 is reduced.

[0135] In addition, it is also possible to use Figure 16 the film forming apparatus 40 shown in (A) of

[0136] In addition, use Figure 16The film forming apparatus 52 in the simplified representation of (B) can also perform the film forming method of the carbon-based film of the present embodiment. Further, 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 stage 14, similarly to the film forming apparatus 101. Then, similarly to the film forming apparatus 101, by controlling the potentials of the electrode plates 221 and 222, ions can be selected from the generated plasma.

[0137] In addition, when controlling the potentials of the electrode plates 221 and 222, for example, in order to stabilize plasma generation, the electrode plate 222 is grounded and a positive voltage is applied to the electrode plate 221. At this time, the positive ions in the plasma are accelerated due to the potential difference between the electrode plate 221 to which the positive voltage is applied and the grounded electrode plate 222. That is, by changing the voltage value of the positive voltage applied to the electrode plate 221, the positive ions in the plasma are adjusted to an appropriate ion energy and supplied to the wafer W.

[0138] In addition, in the film forming apparatus 101, as long as the number of electrode plates disposed between the stage 14 and the upper electrode 20 is at least one or more, the film forming method of the carbon-based film of the present embodiment can be performed. When the number of electrode plates is one, in order to reduce the plasma potential, it is preferable that the frequency of the high-frequency power supplied to the upper electrode 20 is 40 MHz or more. When the number of electrode plates is two or more, the potential difference of the region through which the positive ions in the plasma pass can be finely adjusted, so 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 of, for example, 200 kHz to 460 MHz.

[0139] As described above, by using the film forming apparatus 52, it is also possible to reduce the ion energy imparted to the wafer W placed on the stage 14, similarly to the film forming apparatus 100. That is, in the film forming apparatus 52, it is also possible to reproduce the film forming process performed in the film forming apparatus 100.

[0140] In addition, by using Figure 16The film forming device 54 simplified in (C) can also perform the carbon film forming method of this embodiment. In addition, the film forming device 54 is a conventional capacitively coupled plasma processing device. In the film forming device 52, a conductive ring component 41 is arranged inside the chamber 11 in a manner surrounding the mounting table 14 (lower electrode 17), and the ring component 41 is directly grounded. On the other hand, 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, the impedance of the first electrical path 37 is higher than the impedance of the third electrical path 42 connecting the ring component 41 and the ground wire, so that the ion energy imparted to the wafer W mounted on the mounting table 14 is reduced, similarly to the film forming device 100. That is, the film forming process performed in the film forming device 100 can be reproduced using the evaluation device 40. In addition, the evaluation device 40 does not have the second impedance circuit 36 ​​and the second electrical path 38.

Claims

1. A method for forming a carbon film, characterized in that: The method comprises forming a carbon film on a substrate having a pattern, In the film forming step, plasma is generated from a film forming gas consisting of only hydrocarbon gas, argon gas, and hydrogen gas to selectively form the carbon-based film on the top of the pattern.

2. The method for forming a carbon film according to claim 1, wherein: The hydrocarbon gas is acetylene gas.

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

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

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

6. The method for forming a carbon film according to claim 1, wherein: The pattern is any of grooves and holes.

7. The method for forming a carbon film according to claim 6, wherein: The aspect ratio of the groove and the hole is 2 or more.

8. The method for forming a carbon film according to claim 7, wherein: The aspect ratio of the groove and the hole is 4 or more.

9. The method for forming a carbon film according to claim 1, wherein: In the film forming step, the substrate is received in a processing chamber whose interior is depressurized and placed on a stage arranged inside the processing chamber. The 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 be below 200 eV.

10. The method for forming a carbon film according to claim 1, wherein: In the film forming step, the substrate is received in a processing chamber whose interior is depressurized and placed on a stage arranged inside the processing chamber, the plasma is generated from the film forming gas inside the processing chamber, and a frequency of 40 MHz or more is applied to an electrode opposite to the stage.

11. The method for forming a carbon film according to claim 1, wherein: In the film forming step, the substrate is placed in a processing chamber whose interior is depressurized and mounted on a mounting table arranged inside the processing chamber, and the plasma is generated from the film forming gas inside the processing chamber. At least one electrode is arranged between the electrode facing the mounting table and the mounting table.

12. The method for forming a carbon film according to claim 1, wherein: In the film forming step, the substrate is housed in a processing chamber whose interior is depressurized and is placed on a stage arranged inside the processing chamber. The plasma is generated from the film forming gas inside the processing chamber, and the impedance between the stage and the ground is set to be higher than the impedance between the wall of the processing chamber and the ground.

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

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

15. The method for forming a carbon film according to claim 14, wherein: After etching a 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.

16. The method for forming a carbon film according to claim 14, wherein: Before etching a 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.

17. A film forming device, characterized in that: Including the processing chamber with depressurized interior, A substrate having a pattern is accommodated in the processing chamber, and plasma is generated in the processing chamber from a film forming gas consisting of only hydrocarbon gas, argon gas, and hydrogen gas to selectively form a carbon-based film on top of the pattern.

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

19. The film forming device according to claim 17, wherein: Also includes: a mounting table for mounting the substrate; an electrode opposite to the mounting table; and A high-frequency power source supplies high-frequency power having a frequency of 40 MHz or more to the electrodes.

20. The film forming device according to claim 17, wherein: Also includes: a mounting table for mounting the substrate; an electrode opposite to the mounting table; and At least one electrode is disposed between the mounting table and the electrode.

21. The film forming device according to claim 17, wherein: Also includes: a mounting table for mounting the substrate; and The impedance adjusting unit sets the impedance between the mounting table and the ground to be higher than the impedance between the wall of the processing chamber and the ground.

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