Carbon film forming method and semiconductor device manufacturing method

Abstract

To provide a method for forming a carbon film that is plasma etching resistant and easily removable, and a method for manufacturing semiconductor devices.SOLUTION: A method for forming a carbon film has the processes of: preparing a substrate on which a base layer is formed; depositing a first carbon film on the base layer using a carbon-containing compound; and depositing a second carbon film with ruthenium added by a carbon-containing compound and a ruthenium-containing compound on the carbon film.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for forming a carbon film and a method for manufacturing a semiconductor device. [Background technology]

[0002] Patent Document 1 discloses a method for forming an amorphous carbon film that has high plasma resistance and can be formed at a low temperature, and a method for manufacturing a semiconductor device that applies such an amorphous carbon film forming method. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-224383 Summary of the Invention [Problem to be solved by the invention]

[0004] In plasma etching of an underlayer formed on a substrate, a carbon film may be used as a mask material. This carbon film is required to have improved plasma etching resistance. It is also required to be easily removed from the substrate after the plasma etching of the underlayer.

[0005] In response to the above-mentioned problems, an object of the present invention is to provide a method for forming a carbon film that is resistant to plasma etching and can be easily removed, and a method for manufacturing a semiconductor device. [Means for solving the problem]

[0006] In order to solve the above problem, according to one aspect, a method for manufacturing a substrate having a base layer formed thereon is provided. forming a first carbon film on the underlayer using a carbon-containing compound; The first method is to add ruthenium to a carbon film by using a carbon-containing compound and a ruthenium-containing compound. a step of forming a carbon film of 2; The second carbon film is then coated with Ru X C 1-X In this case, the atomic concentration ratio X of Ru and C is in the range of 0.05≦X≦0.3. A method for forming a carbon film is provided. [Effects of the Invention]

[0007] According to one aspect, it is possible to provide a method for forming a carbon film that is resistant to plasma etching and can be easily removed, and a method for manufacturing a semiconductor device. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a flowchart illustrating a substrate processing method according to an embodiment. [Figure 2] 1 is an example of a schematic cross-sectional view of a substrate. [Figure 3] FIG. 1 is a diagram showing a schematic configuration of a film forming apparatus. [Figure 4] 10 is another example of a schematic cross-sectional view of a substrate. [Figure 5] 3 is a flowchart illustrating a method for manufacturing a semiconductor device according to the first embodiment. [Figure 6] 2 is an example of a schematic cross-sectional view of a substrate in the method for manufacturing a semiconductor device according to the first embodiment. [Figure 7] FIG. 2 is a diagram showing a schematic configuration of an ashing device. [Figure 8] 1 is an example of a graph showing plasma etching resistance of a carbon film doped with ruthenium. [Figure 9] 1 is an example of a graph showing an ashing rate of a carbon film to which ruthenium is added. [Figure 10] 10 is a flowchart illustrating a method for manufacturing a semiconductor device according to a second embodiment. [Figure 11] 10 is an example of a schematic cross-sectional view of a substrate in a method for manufacturing a semiconductor device according to a second embodiment. [Figure 12] 10A and 10B are examples of schematic cross-sectional views of a substrate in a method for manufacturing a semiconductor device according to a reference example. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals, and redundant explanations may be omitted.

[0010] <Substrate processing method> A substrate processing method according to one embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a flowchart illustrating a substrate processing method according to one embodiment. FIG. 2 is an example of a cross-sectional schematic view of a substrate W. In the substrate processing method shown in FIG. 1, a carbon film is formed on the substrate W.

[0011] In step S101, a substrate W is prepared. Here, an underlayer 200 (see FIG. 2) is formed on the substrate W. The underlayer 200 is, for example, a film to be etched that is subjected to plasma etching. The underlayer 200 may be, for example, a SiO film, a SiN film, or a laminated film in which SiO films and SiN films are alternately stacked.

[0012] In step S102, a carbon film (first carbon film) 211 (see FIG. 2) is formed on the underlayer 200 of the substrate W. The carbon film (first carbon film) 211 is, for example, a carbon film that does not contain an additive such as a metal (no additive such as a metal is added).

[0013] In step S103, a ruthenium-doped carbon film (second carbon film) 212 is formed on the carbon film 211 of the substrate W. As a result, the carbon film 211 and the ruthenium-doped carbon film 212 form a laminated carbon film 210. FIG. 2 shows an example of a substrate W on which the laminated carbon film 210 is formed on the underlayer 200. The ruthenium-doped carbon film (second carbon film) 212 is formed thinner than the carbon film (first carbon film) 211.

[0014] Here, a film formation apparatus 300 that forms a laminated carbon film 210 on the substrate W by forming a carbon film 211 on the substrate W in step S102 and a ruthenium-doped carbon film 212 on the substrate W in step S103 will be described with reference to FIG. 3. FIG. 3 is a diagram showing a schematic configuration of the film formation apparatus 300. The film formation apparatus 300 is a plasma CVD (chemical vapor deposition) apparatus that forms the carbon film 211 and the ruthenium-doped carbon film 212 on the substrate W.

[0015] The film forming apparatus 300 has a substantially cylindrical, airtight processing chamber 1. Inside the processing chamber 1, a stage 2 is provided on which a substrate W is placed. The stage 2 is supported by a cylindrical support member 3. A guide ring 4 for guiding the substrate W is provided on the outer edge of the stage 2. As a result, the stage 2 and the guide ring 4 form a substantially circular recess on the upper surface of the stage 2 for placing the substrate W. A heater 5 made of a high-melting-point metal such as molybdenum is embedded in the stage 2. Power is supplied to the heater 5 from a heater power supply 6, and the heater 5 heats the substrate W placed on the stage 2 to a predetermined temperature. The stage 2 also functions as the lower electrode of a parallel plate electrode. The stage 2 is grounded via a transmission line 43. A high-frequency power supply or a DC power supply may be connected to the stage 2 to apply a bias.

[0016] A shower head 10 is provided on the ceiling wall 1a of the processing chamber 1 via an insulating member 9. The shower head 10 functions as an upper electrode of parallel plate electrodes and faces the stage 2 serving as a lower electrode. A high-frequency power supply 42 is connected to the shower head 10 via a matching box 41. By supplying high-frequency power of, for example, 400 kHz to 100 MHz from the high-frequency power supply 42 to the upper electrode (shower head 10), a high-frequency electric field is generated between the upper electrode (shower head 10) and the lower electrode (stage 2), and capacitively coupled plasma is generated. The plasma generation unit 40 includes the matching box 41 and the high-frequency power supply 42. Note that the plasma generation unit 40 is not limited to generating capacitively coupled plasma, and may also generate other types of plasma, such as inductively coupled plasma.

[0017] The shower head 10 includes a base member 11 and a shower plate 12. A gas diffusion space 13 is formed between the base member 11 and the shower plate 12. The shower plate 12 has a large number of gas outlet holes 14, for example, evenly arranged, for dispersing and supplying gas from the gas diffusion space 13 into the processing chamber 1. A gas inlet hole 15 communicating with the gas diffusion space 13 is formed near the center of the base member 11. The gas inlet hole 15 is connected to gas supply lines 21d to 24d of the gas supply unit 20 via gas piping 16. A heat insulating member 17 is provided in a recess formed in the upper part of the base member 11.

[0018] The gas supply unit 20 includes a carbon-containing gas supply source 21, a ruthenium-containing gas supply source 22, an Ar gas supply source 23, and a He gas supply source 24.

[0019] The carbon-containing gas supply source 21 supplies a carbon (C)-containing compound gas (carbon (C)-containing gas). Specifically, the carbon-containing gas supply source 21 supplies a hydrocarbon gas (C x H y As the hydrocarbon gas, for example, a gas containing at least one of CH4, C2H2, C3H4, C3H6, C3H8, etc. can be used.

[0020] The ruthenium-containing gas supply source 22 supplies a ruthenium (Ru)-containing compound gas (ruthenium (Ru)-containing gas). Specifically, the ruthenium-containing gas supply source 22 supplies a ruthenium precursor gas. Examples of the ruthenium precursor gas include EtCpRu ((C2H5C5H5)2Ru), Ru(C5H4C2H5), and Ru(C 11 H 19 O2)3, Ru3(CO) 12 A gas containing at least one of the organic ruthenium gases such as the above can be used.

[0021] The Ar gas supply source 23 supplies Ar gas used as a plasma generating gas, a purge gas, a carrier gas for the carbon-containing gas, and a ruthenium-containing gas.

[0022] The He gas supply source 24 supplies He gas used as a plasma generating gas, a purge gas, a carrier gas for a carbon-containing gas, a ruthenium-containing gas, and the like.

[0023] The carbon-containing gas supply source 21 is connected to the gas pipe 16 via a gas supply line 21d. The gas supply line 21d is provided with a valve 21a, a mass flow controller 21b, and a valve 21c. The mass flow controller 21b controls the flow rate of the carbon (C)-containing compound gas flowing through the gas supply line 21d. The valves 21a and 21c open and close to supply and cut off the carbon (C)-containing compound gas to the gas pipe 16.

[0024] The ruthenium-containing gas supply source 22 is connected to the gas pipe 16 via a gas supply line 22d. The gas supply line 22d is provided with a valve 22a, a mass flow controller 22b, and a valve 22c. The mass flow controller 22b controls the flow rate of the ruthenium (Ru)-containing compound gas flowing through the gas supply line 22d. The valves 22a and 22c open and close to supply and cut off the ruthenium (Ru)-containing compound gas to the gas pipe 16.

[0025] The Ar gas supply source 23 is connected to the gas pipe 16 via a gas supply line 23d. A valve 23a, a mass flow controller 23b, and a valve 23c are provided on the gas supply line 23d. The mass flow controller 23b controls the flow rate of the Ar gas flowing through the gas supply line 23d. The valves 23a and 23c open and close to supply and cut off the Ar gas to the gas pipe 16.

[0026] The He gas supply source 24 is connected to the gas pipe 16 via a gas supply line 24d. A valve 24a, a mass flow controller 24b, and a valve 24c are provided on the gas supply line 24d. The mass flow controller 24b controls the flow rate of the He gas flowing through the gas supply line 24d. The valves 24a and 24c open and close to supply and cut off the He gas to the gas pipe 16.

[0027] Gases supplied from gas supply lines 21d to 24d to gas pipe 16 are supplied to gas diffusion space 13 via gas inlet hole 15, and then passed through gas outlet holes 14 of shower plate 12 and discharged into processing chamber 1.

[0028] A substantially circular hole 50 is formed in the center of the bottom wall 1b of the processing vessel 1. An exhaust chamber 51 is provided in the bottom wall 1b, protruding downward to cover the hole 50. An exhaust pipe 52 is connected to the side of the exhaust chamber 51. An exhaust device 53 is connected to the exhaust pipe 52. Thus, the exhaust pipe 52 is configured so that the pressure inside the processing vessel 1 can be reduced by the exhaust device 53.

[0029] The stage 2 is provided with a plurality of (for example, three) wafer support pins 54 for supporting and raising and lowering the substrate W. The plurality of wafer support pins 54 are provided so as to be able to protrude and retract from the surface of the stage 2, and are supported by a support plate 55. The wafer support pins 54 are configured to be able to be raised and lowered via the support plate 55 by a drive mechanism 56.

[0030] A transfer port 57 is provided in a sidewall of the processing vessel 1. The transfer port 57 is opened and closed by a gate valve 58. The substrate W is transferred in and out between the processing vessel 1 and a transfer chamber (not shown) through the transfer port 57.

[0031] The film forming apparatus 300 also includes a control device 60. The control device 60 is, for example, a computer, and includes a control unit 61 and a storage unit 62. The storage unit 62 stores programs that control various processes executed in the film forming apparatus 300. The control unit 61 controls the operation of the film forming apparatus 300 by reading and executing the programs stored in the storage unit 62.

[0032] A user interface 63 is also connected to the control device 60. The user interface 63 has an input device through which an operator inputs commands to manage the film forming apparatus 300, and an output device such as a display that visualizes and displays the operating status of the film forming apparatus 300.

[0033] With this configuration, the film formation apparatus 300 can form a carbon film 211 on the substrate W by plasma CVD processing by supplying a carbon (C)-containing compound gas from the gas supply unit 20 into the processing chamber 1.

[0034] Furthermore, the film formation apparatus 300 can form a carbon film 212 doped with ruthenium on the substrate W by plasma CVD processing by simultaneously supplying a carbon (C)-containing compound gas and a ruthenium (Ru)-containing compound gas from the gas supply unit 20 into the processing vessel 1. In other words, the film formation apparatus 300 supplies a carbon (C)-containing compound gas from the gas supply unit 20 into the processing vessel 1 and forms a carbon film on the substrate W by plasma CVD processing. Here, the film formation apparatus 300 can simultaneously supply a ruthenium (Ru)-containing compound gas from the gas supply unit 20 into the processing vessel 1, thereby doping ruthenium (Ru) into the carbon film and forming a carbon film 212 doped with ruthenium on the substrate W.

[0035] In addition, the film forming apparatus 300 can control the amount of ruthenium added to the carbon film formed on the substrate W by controlling the flow rate of the ruthenium (Ru)-containing compound gas supplied from the ruthenium-containing gas supply source 22 to the gas pipe 16.

[0036] Although the film formation apparatus 300 has been described as forming the ruthenium-doped carbon film 212 on the substrate W by plasma CVD processing, the present invention is not limited thereto. For example, the film formation apparatus 300 may form the ruthenium-doped carbon film 212 on the substrate W by alternately supplying a carbon (C)-containing compound gas and a ruthenium (Ru)-containing compound gas from the gas supply unit 20 into the processing chamber 1. Specifically, the film formation apparatus 300 performs a carbon film formation process in which a carbon film is formed on the substrate W by plasma CVD processing by supplying a carbon (C)-containing compound gas from the gas supply unit 20 into the processing chamber 1. Next, the film formation apparatus 300 performs a ruthenium adsorption process in which ruthenium (Ru) is adsorbed onto the surface of the carbon film formed on the substrate W by supplying a ruthenium (Ru)-containing compound gas from the gas supply unit 20 into the processing chamber 1. Then, the carbon film forming step and the ruthenium adsorption step may be alternately repeated to form the carbon film 212 on the substrate W to which ruthenium has been added.

[0037] Furthermore, for example, the film formation apparatus 300 may intermittently supply a ruthenium (Ru)-containing compound gas into the processing chamber 1 while supplying a carbon (C)-containing compound gas from the gas supply unit 20, thereby forming a ruthenium-doped carbon film 212 on the substrate W. This makes it possible to control the amount of ruthenium added to the carbon film.

[0038] Furthermore, the film formation apparatus 300 has been described as supplying a carbon (C)-containing compound gas and a ruthenium (Ru)-containing compound gas to the processing chamber 1 to form the carbon film 211 and the ruthenium-doped carbon film 212 on the substrate W, but the present invention is not limited thereto. The film formation apparatus for forming the carbon film 211 and the ruthenium-doped carbon film 212 on the substrate W may be a sputtering apparatus that sputters a target to form a film on the substrate W. That is, the film formation apparatus may be a sputtering apparatus having a target of a carbon (C)-containing compound and a target of a ruthenium (Ru)-containing compound. The sputtering apparatus forms the carbon film 211 by sputtering only the carbon (C)-containing compound target using plasma. The sputtering apparatus forms the ruthenium-doped carbon film 212 by sputtering two targets using plasma. When forming the ruthenium-doped carbon film 212, the sputtering apparatus may be configured to sputter two targets simultaneously or two targets alternately. The sputtering apparatus may also be configured to sputter two targets at any timing, thereby allowing the amount of ruthenium to be added to be controlled.

[0039] As described above, the film formation apparatus 300 can form the laminated carbon film 210 on the substrate W. Furthermore, the film formation apparatus 300 can control the amount of ruthenium added when forming the carbon film 212 to which ruthenium is added.

[0040] The laminated carbon film 210 formed by the film forming apparatus 300 is not limited to the configuration shown in FIG. 2. FIG. 4 is another example of a schematic cross-sectional view of a substrate W. The film forming apparatus 300 forms a carbon film 221 on the underlayer 200 of the substrate W. The carbon film 221 is, for example, a carbon film that does not contain an additive such as a metal (no additive such as a metal is added). The film forming apparatus 300 then forms ruthenium-doped carbon films 222 to 225 in order on the carbon film 221 of the substrate W, thereby forming the laminated carbon film 220. Here, the amount of ruthenium added increases in the ruthenium-doped carbon films 222 to 225 toward the top. In FIG. 4, the amount of ruthenium added is schematically indicated by the shade of hatching applied to the ruthenium-doped carbon films 222 to 225.

[0041] The laminated carbon film 220 may be formed so that the amount of ruthenium added increases from the lower layer to the upper layer. The laminated carbon film 220 may also be formed so that the amount of ruthenium added increases continuously from the upper layer. The number of layers in the laminated carbon film 220 is not limited to five.

[0042] <Method of manufacturing a semiconductor device> Next, a method for manufacturing a semiconductor device, in which the above-mentioned ruthenium-doped carbon film is used as a hard mask to etch an underlayer, will be described with reference to Figures 5 and 6. Figure 5 is a flowchart illustrating the method for manufacturing a semiconductor device according to the first embodiment. Figure 6 is an example of a schematic cross-sectional view of a substrate W in the method for manufacturing a semiconductor device according to the first embodiment.

[0043] In step S401, a substrate W is prepared. Here, an underlayer 500 (see FIG. 6(a)) is formed on the substrate W. The underlayer 500 is a film to be etched, which is subjected to plasma etching using a hard mask 510 (described later) as a mask. The underlayer 500 may be, for example, a SiO2 film, a SiN film, or a laminated film in which SiO2 films and SiN films are alternately stacked.

[0044] In step S402, a hard mask 510 made of a laminated carbon film is formed on the underlayer 500 of the substrate W. The hard mask 510 is formed by laminating a ruthenium-doped carbon film 512 on a carbon film 511. The carbon film 511 is, for example, a carbon film that does not contain an additive such as a metal (no additive such as a metal is added). The method for forming the hard mask 510 is the same as the method for forming the laminated carbon film 210 shown in FIGS. 1 to 3, and therefore, a redundant description will be omitted. The configuration of the hard mask 510 is not limited thereto, and the carbon film (see FIG. 4) may be formed so that the amount of ruthenium added increases from the lower layer to the upper layer. In the following description, it is assumed that the hard mask 510 is formed by forming a carbon film 511 on the underlayer 500 and then laminating a ruthenium-doped carbon film 512 thereon, as shown in FIG. 6(a).

[0045] In step S403, a pattern is formed in the hard mask 510. Here, a resist film (not shown) having a pattern is formed on the hard mask 510. Next, the hard mask 510 is etched using the resist film on which the pattern is formed as a mask, thereby forming a pattern in the hard mask 510. As a result, as shown in FIG. 6(b), recesses 515 having patterns such as vias, holes, and trenches are formed in the hard mask 510.

[0046] The process of etching the hard mask 510 using a resist film (not shown) as a mask uses, for example, O 2 gas or H 2 gas as an etching gas to etch the ruthenium-added carbon film 512 and the carbon film 511.

[0047] In step S404, the hard mask 510 having the recesses 515 formed therein is used as a mask to plasma etch the base layer 500. As a result, recesses 505 are formed in the base layer 500, as shown in FIG.

[0048] Here, when etching the underlayer 500, the etching process is performed at a low temperature of the substrate W at 0°C or below. Furthermore, the process of etching the underlayer 500 using the hard mask 510 as a mask can be performed under the same conditions as the process of etching the underlayer 500 (e.g., a SiO2 film, a SiN film, a laminated film in which SiO2 films and SiN films are alternately stacked, etc.). For example, the underlayer 500 is etched using a fluorine-containing gas (e.g., a gas containing at least one of C4F6, C4F8, O2, and CH2F2) as an etching gas under the condition of applying a high bias.

[0049] In step S405, the hard mask 510 is removed from the substrate W. As described above, by the process shown in the flowchart of Fig. 5, a pattern of recesses 505 can be formed in the underlayer 500 of the substrate W, as shown in Fig. 6(d).

[0050] Here, the ashing apparatus 600 that removes the hard mask 510 in step S405 will be described with reference to Fig. 7. Fig. 7 is a diagram showing a schematic configuration of the ashing apparatus 600. The ashing apparatus 600 is a film forming apparatus that removes (ashes) the hard mask 510.

[0051] The ashing apparatus 600 (see FIG. 7) differs from the film forming apparatus 300 (see FIG. 3) in the gas supplied to the processing chamber 1. That is, the gas supplied by the gas supply unit 20 is different. The rest of the configuration of the ashing apparatus 600 is the same as the configuration of the film forming apparatus 300, and therefore, a duplicated description will be omitted.

[0052] The gas supply unit 20 of the ashing device 600 has an oxygen-containing gas supply source 25 .

[0053] The oxygen-containing gas supply source 25 supplies an oxygen (O)-containing gas. Specifically, the oxygen-containing gas supply source 25 supplies, for example, O2 gas.

[0054] The oxygen-containing gas supply source 25 is connected to the gas pipe 16 via a gas supply line 25d. The gas supply line 25d is provided with a valve 25a, a mass flow controller 25b, and a valve 25c. The mass flow controller 25b controls the flow rate of the oxygen (O)-containing gas flowing through the gas supply line 25d. The valves 25a and 25c open and close to supply and cut off the oxygen (O)-containing gas to the gas pipe 16.

[0055] Gas supplied from gas supply line 25 d to gas pipe 16 is supplied to gas diffusion space 13 via gas inlet hole 15 , passes through gas outlet holes 14 of shower plate 12 , and is then discharged into processing chamber 1 .

[0056] With this configuration, the ashing device 600 supplies an oxygen (O)-containing gas from the gas supply unit 20 into the processing chamber 1, and generates oxygen plasma in the processing chamber 1, thereby removing the hard mask 510 (the carbon film 511 and the ruthenium-added carbon film 512) formed on the substrate W by ashing.

[0057] Here, carbon (C) in the hard mask 510 combines with oxygen (O) in the plasma and is exhausted as gas by the exhaust device 53.

[0058] C+2O→CO2↑(gas)

[0059] Furthermore, ruthenium (Ru) in the hard mask 510 combines with oxygen (O) in the plasma and is exhausted as a gas by the exhaust device 53.

[0060] Ru+4O→RuO4↑(gas)

[0061] In this way, the ashing apparatus 600 can ash the carbon film and also ash the ruthenium (Ru) added to the carbon film, thereby enabling the ashing apparatus 600 to remove the hard mask 510 from the substrate W.

[0062] Next, the characteristics of the ruthenium-doped carbon films 212 and 512 formed in step S102 and step S402 will be described with reference to FIGS.

[0063] FIG. 8 is an example of a graph showing the plasma etching resistance of the ruthenium-doped carbon films 212, 512 in a process of plasma etching the underlayer 200 (underlayer 500).

[0064] Here, a sputtering apparatus was used as the film formation apparatus 300 in step S102 (step S402), and ruthenium-doped carbon films 212, 512 with different amounts of ruthenium added were formed on the substrate W. Then, plasma etching processes were performed under the processing conditions in step S404 on the substrates W on which the ruthenium-doped carbon films 212, 512 had been formed.

[0065] In the graph shown in FIG. 8, the horizontal axis represents the amount of ruthenium added to the carbon film (the carbon film 212, 512 to which ruthenium has been added is represented by Ru X C 1-X The graph shows the atomic concentration ratio X (%) of Ru and C when the horizontal axis is 0%. That is, a value of 0% on the horizontal axis indicates a carbon film with no ruthenium added (indicated by a circle). A value of 100% on the horizontal axis indicates a ruthenium film (indicated by a triangle). A value between 0% and 100% on the horizontal axis indicates a carbon film with ruthenium added (indicated by a diamond).

[0066] In the graph shown in FIG. 8, the vertical axis indicates the etching rate ratio of the ruthenium-added carbon films 212 and 512 normalized with the etching rate of the amorphous carbon film set to 1.

[0067] In the carbon film shown at 0% (see circle), the carbon film formed by sputtering has a higher etching rate than the amorphous carbon film.

[0068] On the other hand, in the ruthenium film shown at 100% (see triangles), the ruthenium film formed by sputtering has a lower etching rate than the amorphous carbon film, meaning that the etching resistance is improved.

[0069] Furthermore, the etching rate significantly decreases when the amount of ruthenium added to the carbon film is 5% or more in atomic concentration ratio (see diamonds). Therefore, the amount of ruthenium added to the carbon film is preferably 5% or more in atomic concentration ratio. This significantly improves the etching resistance of the carbon film 212, 512 to which ruthenium has been added.

[0070] Furthermore, when the amount of ruthenium added to the carbon film reaches 30% or more in atomic concentration ratio (see diamond marks), the etching rate decreases to the same level as that of the ruthenium film (see triangle marks). Therefore, the amount of ruthenium added to the carbon film is preferably 30% or less in atomic concentration ratio. This makes it possible to ensure high etching resistance while suppressing the amount of ruthenium added in the ruthenium-doped carbon film 212, 512. Furthermore, by reducing the amount of ruthenium added, the cost of the ruthenium-doped carbon film 212, 512 can be reduced. Furthermore, since the metal atoms used in the ruthenium-doped carbon film 212, 512 can be reduced, metal contamination in the processing chamber 1 can be suppressed.

[0071] In this way, by using the ruthenium-doped carbon film, it is possible to etch the underlayer 200 (underlayer 500) in the plasma etching process while suppressing etching of the ruthenium-doped carbon films 212, 512. That is, by using the ruthenium-doped carbon film, it is possible to improve the selectivity between the ruthenium-doped carbon films 212, 512 and the underlayer 200 (underlayer 500) in the plasma etching process. This makes it possible to improve the accuracy of the shape (e.g., recess 505) of a recess such as a trench formed in the underlayer 200 (underlayer 500), for example.

[0072] Furthermore, in the plasma etching process of the underlayer 200 (underlayer 500), a fluorine-containing gas is used as the etching gas at a low temperature of the substrate W below 0°C. Therefore, the material of the ruthenium-doped carbon film 212, 512 is required to have a low fluoride vapor pressure at temperatures below room temperature. In other words, the fluoride of the material of the ruthenium-doped carbon film 212, 512 is preferably a material that is not a gas. Here, ruthenium (Ru) fluoride is solid at around room temperature. Therefore, a ruthenium-doped carbon film can be used as the material of the hard mask 510.

[0073] In this way, by using a carbon film doped with ruthenium as the material for the upper layer of the hard mask 510, it is possible to prevent the upper corners of the hard mask 510 from being etched and becoming convex when the base layer 500 is plasma etched, thereby improving the processing accuracy of the recesses 505 formed in the base layer 500.

[0074] FIG. 9 is an example of a graph showing the ashing rate of the carbon films 212 and 512 to which ruthenium is added in the ashing process.

[0075] Here, a sputtering apparatus was used as the film formation apparatus 300 in step S102 (step S402), and ruthenium-doped carbon films 212, 512 with varying amounts of ruthenium added were formed on the substrate W. Then, an ashing process was performed on the substrate W on which the ruthenium-doped carbon films 212, 512 had been formed. Here, plasma ashing was performed at a substrate temperature of 60°C, HF of 1 kW, LF of 0.3 kW, pressure of 30 mT, supply gas of O2 gas, flow rate of 800 sccm, and etching time of 20 min.

[0076] In the graph shown in FIG. 9, the horizontal axis represents the amount of ruthenium added to the carbon film (the carbon film 212, 512 to which ruthenium has been added is represented by Ru X C 1-XThe vertical axis shows the atomic concentration ratio X (%) of Ru and C when the atomic concentration is 1 / 2. The vertical axis shows the ashing rate (nm / min).

[0077] As shown in FIG. 9, it is shown that the carbon film without added ruthenium (0%) can be ashed using O2 gas plasma.

[0078] Here, ruthenium (Ru) combines with oxygen (O) to form a compound that is volatile at room temperature and atmospheric pressure. Therefore, as shown in Figure 9, carbon films doped with ruthenium can also be ashed using O2 gas plasma, similar to the ashing process for carbon films (0%).

[0079] As described above, by adding ruthenium to the carbon film, the etching resistance can be improved, and thus the selectivity between the ruthenium-added carbon film 212, 512 and the underlayer 200 (underlayer 500) can be improved during plasma etching.

[0080] Furthermore, by adding ruthenium to the carbon film, it can be removed by ashing in the same manner as a carbon film without adding ruthenium.

[0081] <Method of manufacturing a semiconductor device> Next, a method for manufacturing a semiconductor device according to the second embodiment will be described with reference to Fig. 10 and Fig. 11. Fig. 10 is a flowchart illustrating the method for manufacturing a semiconductor device according to the second embodiment. Fig. 11 is an example of a schematic cross-sectional view of a substrate W in the method for manufacturing a semiconductor device according to the second embodiment.

[0082] In step S701, a substrate W is prepared. Here, an underlayer 800 (see FIG. 11(a)) is formed on the substrate W. The underlayer 800 is a film to be etched, which is subjected to plasma etching using a hard mask 830 (described later) as a mask. The underlayer 800 may be, for example, a SiO2 film, a SiN film, or a laminated film in which SiO2 films and SiN films are alternately stacked.

[0083] In step S702, a carbon film (first carbon film) 831 is formed on the underlayer 800 of the substrate W. The carbon film 831 is, for example, a carbon film that does not contain an additive such as a metal (no additive such as a metal is added). The method for forming the carbon film 831 is the same as the method for forming the carbon film 211 shown in FIGS. 1 to 3, and therefore a duplicated description will be omitted.

[0084] In step S703, a pattern is formed on the carbon film 831. Here, a resist film (not shown) having a pattern is formed on the carbon film 831. Next, the carbon film 831 is etched using the resist film on which the pattern has been formed as a mask, thereby forming a pattern on the carbon film 831. As a result, as shown in FIG. 11(b), recesses 835 having a pattern such as vias, holes, and trenches are formed in the carbon film 831.

[0085] In step S704, a ruthenium-doped carbon film (second carbon film, RuC film) 832 is formed on the upper surface of the patterned carbon film 831 and on the side surfaces of the recesses 835. Here, the ruthenium-doped carbon film 832 is formed thinner than the carbon film 831. As a result, as shown in FIG. 11(c), the ruthenium-doped carbon film 832 is formed on the upper surface of the patterned carbon film 831 and on the side surfaces of the recesses 835. As a result, the patterned carbon film 831 and the ruthenium-doped carbon film 832 form a patterned hard mask 830.

[0086] In step S705, the underlying layer 800 is plasma etched using the patterned hard mask 830 as a mask, thereby forming recesses 805 in the underlying layer 800, as shown in FIG.

[0087] In step S706, the hard mask 830 is removed by ashing from the substrate W. As described above, by the process shown in the flowchart of Fig. 10, a pattern of recesses 805 can be formed in the base layer 800 of the substrate W, as shown in Fig. 11(e).

[0088] Here, a method for manufacturing a semiconductor device according to a reference example will be described with reference to Fig. 12. Fig. 12 is an example of a schematic cross-sectional view of a substrate W in the method for manufacturing a semiconductor device according to a reference example.

[0089] In the method for manufacturing a semiconductor device according to the reference example, first, as shown in Fig. 12(a), a carbon film 831 is formed on an underlayer 800 of a substrate W. Next, as shown in Fig. 12(b), a pattern is formed in the carbon film 831. Then, as shown in Fig. 12(c), the underlayer 800 is plasma etched using the patterned carbon film 831 as a mask.

[0090] Here, when the base layer 800 is plasma etched using the carbon film 831 as a mask, the upper corners of the carbon film 831 are also etched, causing the shape of the carbon film 831 to become convex. This may cause the shape of the recess 805 formed in the base layer 800 to become distorted.

[0091] 11(d), in the hard mask 830, the upper surface of the carbon film 831 and the side surfaces of the recesses 835 are covered with a carbon film 832 doped with ruthenium, which has etching resistance. When the base layer 800 is plasma-etched using the hard mask 830 as a mask, the upper corners of the hard mask 830 can be prevented from being etched and becoming convex. This improves the processing accuracy of the recesses 805 formed in the base layer 800. [Explanation of symbols]

[0092] 200,500,800 Base layer 210,220 Laminated carbon film 211,221,511,831 Carbon film 212,222~225,512,832 Ruthenium-doped carbon film 300 Film deposition equipment 510,830 Hard Mask 600 Ashing Device

Claims

1. preparing a substrate on which an underlayer is formed; forming a first carbon film on the underlayer using a carbon-containing compound; forming a second carbon film on the first carbon film by adding ruthenium using a carbon-containing compound and a ruthenium-containing compound; When the second carbon film is represented as Ru X C 1-X , the atomic concentration ratio X of Ru to C is in the range of 0.05≦X≦0.

3. A method for forming a carbon film.

2. The second carbon film has a thickness smaller than that of the first carbon film. The method for forming a carbon film according to claim 1 .

3. The step of forming the second carbon film includes: The second carbon film is formed so that the amount of ruthenium added increases toward the upper layer. The method for forming a carbon film according to claim 1 .

4. The method further includes a step of forming a pattern on a laminated carbon film formed of the first carbon film and the second carbon film. The method for forming a carbon film according to any one of claims 1 to 3.

5. The method further includes forming a pattern on the first carbon film, The step of forming the second carbon film includes: forming the second carbon film on the first carbon film on which the pattern has been formed; The method for forming a carbon film according to any one of claims 1 to 3.

6. The step of forming the second carbon film includes: a gas containing the carbon-containing compound and a gas containing the ruthenium-containing compound are simultaneously supplied into a processing vessel accommodating the substrate, and plasma is generated in the processing vessel to deposit the second carbon film; The method for forming a carbon film according to any one of claims 1 to 5.

7. The step of forming the second carbon film includes: supplying a gas containing the carbon-containing compound into a processing vessel containing the substrate to generate plasma in the processing vessel, thereby forming a carbon film on the substrate; supplying a gas containing the ruthenium-containing compound to the processing vessel to adsorb ruthenium onto the carbon film; The method for forming a carbon film according to any one of claims 1 to 5.

8. The gas containing the carbon-containing compound is CH ４ , C ２ H ２ , C ３ H ４ , C ３ H ６ , C ３ H ８ A gas containing at least one of 8. The method for forming a carbon film according to claim 6 or 7.

9. The gas containing the ruthenium-containing compound is EtCp ２ Ru((C ２ H ５ C ５ H ５ ) ２ Ru), Ru(C ５ H ４ C ２ H ５ ) ２ , Ru(C １１ H １９ O ２ ) ３ , Ru ３ (CO) １２ A gas containing at least one of 9. The method for forming a carbon film according to claim 6.

10. The step of forming the second carbon film includes: sputtering a target containing the carbon-containing compound and a target containing the ruthenium-containing compound to form a carbon film doped with the ruthenium; The method for forming a carbon film according to any one of claims 1 to 5.

11. forming a hard mask on the underlayer formed on the substrate by the method for forming a carbon film according to any one of claims 1 to 10; forming a pattern on the hard mask; plasma etching the underlayer through the patterned hard mask; ashing the hard mask. A method for manufacturing a semiconductor device.

12. The step of etching the underlayer includes: Using a fluorine-containing gas, The method for manufacturing a semiconductor device according to claim 11 .

13. The step of etching the underlayer includes: The substrate is treated at a temperature of 0°C or less. The method for manufacturing a semiconductor device according to claim 11 or 12.

14. The step of ashing the hard mask includes: O ２ Using gas plasma, The method for manufacturing a semiconductor device according to any one of claims 11 to 13.

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