Carbon film forming method and carbon film forming apparatus

Abstract

The present invention addresses the problem of forming a carbon film having high etching resistance. The solution is that a carbon film raw material is coated on a substrate by a spin coating method to form a carbon-containing film on the substrate, the carbon-containing film is heated and fired to form a carbon film, and the carbon film is irradiated with helium ions.

Description

TECHNICAL FIELD

[0001] The present application relates to a carbon film forming method and a carbon film forming apparatus. BACKGROUND

[0002] Generally, in a semiconductor device, as a base layer of a photoresist film using extreme ultraviolet exposure, an SOC (Spin on Carbon) film is used. For example, in the technology of Patent Literature 1, first, an SOC is applied on a silicon oxide film, and baking treatment is performed to form an organic film (hereinafter referred to as "SOC film") composed of the SOC, and further, a SOG (Spin on Glass) is applied on the SOC film, and baking treatment is performed to form a SOG film. Next, a resist is applied on the SOG film, a hole pattern is formed by a lithography process, and thereafter, RIE (Reactive Ion Etching) is performed with the resist as a mask to transfer the hole pattern to the SOG film. Further, RIE is performed with the SOG film on which the hole pattern is transferred as a mask to transfer the hole pattern to the SOC film. Then, RIE is performed with the SOC film on which the hole pattern is transferred as a hard mask to transfer the hole pattern to the silicon oxide film.

[0003] PRIOR ART DOCUMENTS

[0004] PATENT LITERATURE

[0005] Patent Literature 1: Japanese Patent Application Publication No. 2014-135435 SUMMARY

[0006] PROBLEMS TO BE SOLVED BY THE INVENTION

[0007] The technology of the present application is to form a carbon film having high etching resistance.

[0008] MEANS OF SOLVING THE PROBLEMS

[0009] One embodiment of the technology of the present application is a carbon film forming method in which a carbon film raw material is applied on a substrate by a spin coating method to form a carbon-containing film on the substrate, the carbon-containing film is heated and fired to form a carbon film, and the carbon film is irradiated with helium ions.

[0010] EFFECTS OF THE INVENTION

[0011] According to the technology of the present application, a carbon film having high etching resistance can be formed. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 is a view showing the structure of a carbon film forming apparatus that executes a carbon film forming method that is one embodiment of the technology of the present application.

[0013] Figure 2 is a view showing the structure of a carbon film forming apparatus that executes a carbon film forming method that is one embodiment of the technology of the present application.Figure 1 FIG. 2 is a sectional view of the structure of the plasma processing apparatus in Example 1.

[0014] Figure 3A FIG. 6 is a graph showing various characteristics of the SOC film when the bias electric power at the time of irradiation of ions to the SOC film is changed.

[0015] Figure 3B FIG. 6 is a graph showing various characteristics of the SOC film when the bias electric power at the time of irradiation of ions to the SOC film is changed.

[0016] Figure 4 FIG. 7 is a graph showing the etching rate of RIE of the SOC film when the internal pressure of the processing container at the time of irradiation of ions to the SOC film is changed.

[0017] Figure 5 FIG. 8 is a graph showing the etching rate of RIE of the SOC film when the temperature of the wafer at the time of irradiation of ions to the SOC film is changed.

[0018] Figure 6 FIG. 9 is a graph showing the etching rate of RIE of the SOC film when the irradiation time of ions to the SOC film is changed.

[0019] Figure 7 FIG. 10 is a graph showing the etching rate of RIE of the SOC film when the baking temperature of the carbon-containing film is changed.

[0020] Figure 8 FIG. 11 is a flowchart showing the carbon film forming method according to one embodiment of the present technology.

[0021] Figure 9 FIG. 12 is a graph showing the results of comparing the etching rates of the SOC film formed by the carbon film forming method according to one embodiment of the present technology and the amorphous carbon film.

[0022] Figure 10 FIG. 13 is a graph showing the relative comparison of various characteristics of the SOC film formed by the carbon film forming method according to one embodiment of the present technology and the conventional (existing) SOC film. DETAILED DESCRIPTION

[0023] The etching resistance of the SOC film used as a hard mask in RIE is not very high, and sometimes in the etching of the silicon oxide film, the hard mask is eroded to cause the hole pattern to become large. In this case, the opening of the hole pattern transferred to the silicon oxide film is enlarged.

[0024] For this reason, the SOC formed by spin coating is heated and baked at a relatively high temperature (for example, 500°C or higher), thereby densifying the SOC film to improve the etching resistance.

[0025] However, with the recent complexification of the structure of semiconductor devices, the manufacturing process of the semiconductor devices requires processing at a lower temperature than ever before, for example, there is a demand for heating and baking of the SOC film to be performed at a temperature of less than 500°C. However, in the case where heating and baking of the SOC film is performed at less than 500°C, it is difficult to sufficiently densify the SOC film, and it is difficult to form a SOC film with high etching resistance.

[0026] To address this, the technology of the present application irradiates a SOC film, on which heating and baking has been performed, with helium ions, densifies the SOC film sufficiently, and forms a SOC film with high etching resistance.

[0027] Hereinafter, one embodiment of the technology of the present application will be described with reference to the drawings. Figure 1 is a view showing the structure of a carbon film forming apparatus that performs a carbon film forming method as the present embodiment.

[0028] In Figure 1 , the carbon film forming apparatus 10 includes a coating and developing apparatus 11 and a plasma processing apparatus 12. The coating and developing apparatus 11 has a spin coating section and a heating and baking section (neither of which is shown). The spin coating section forms a carbon-containing film on the surface of a wafer (substrate), specifically, on a silicon oxide film of the wafer, by coating the wafer with a SOC film raw material by spin coating (spin coating method). The heating and baking section heats the wafer on which the carbon-containing film is formed, either one wafer at a time or a plurality of wafers at the same time, and performs a baking process on the carbon-containing film to form a SOC film (carbon film) from the carbon-containing film. As a method of heating the wafer in the heating and baking section, for example, a method of heating using a heater built into a stage on which the wafer is placed, a method of heating by irradiating the wafer with infrared rays, and a method of heating by blowing hot air against the wafer can be given. In addition, the plasma processing apparatus 12 (ion irradiation section) irradiates the wafer on which the SOC film is formed by heating and baking with helium ions.

[0029] Figure 2 is a cross-sectional view schematically showing the structure of the plasma processing apparatus 12 in Figure 1 . In Figure 2 , the plasma processing apparatus 12 includes a processing container 13 that accommodates a wafer W. Inside the processing container 13, a stage 14 on which the wafer W is placed is arranged, and the stage 14 is supported by a column portion 15 from the bottom of the processing container 13. A baffle 16 is arranged between the stage 14 and the side wall of the processing container 13, and a large number of air vents 16a are formed in the baffle 16. In addition, in the processing container 13, a processing space U is formed between the stage 14 and the ceiling portion of the processing container 13. In the processing space U, as will be described later, a plasma is generated from helium gas.

[0030] An electrostatic chuck 17 is provided on the upper portion of the stage 14, and a wafer W placed on the stage 14 is held by electrostatic force of the electrostatic chuck 17. In addition, in the interior of the stage 14, a temperature control mechanism such as a heater 18, a cooler (not shown), and the like is provided in order to control the temperature of the placed wafer W. On the upper surface of the stage 14, a ring-shaped focus ring 19 is arranged in a manner so as to surround the placed wafer W. In addition, a load lock port 20 for loading and unloading the wafer W to and from the processing space U, and a gate valve 21 for opening and closing the load lock port 20 are provided on the side wall of the processing container 13.

[0031] On the ceiling portion of the processing container 13, a processing gas supply device 23 is connected via a gas supply pipe 22. The processing gas supply device 23 supplies a single gas of helium gas as a processing gas to the processing space U. In addition, a first high-frequency power supply 24 and a second high-frequency power supply 25 are connected to the stage 14. Thereby, the stage 14 functions as a lower electrode. The first high-frequency power supply 24 supplies, for example, a high-frequency electric power of 100 MHz for plasma generation to the stage 14, and the second high-frequency power supply 25 supplies, for example, a high-frequency electric power of 400 kHz to 13 MHz for ion attraction (hereinafter referred to as "bias electric power") to the stage 14.

[0032] The high-frequency electric power for plasma generation generates an electric field in the processing space U, and the electric field excites the helium gas supplied to the processing space U to generate plasma. In addition, helium ions in the plasma are attracted toward the stage 14 by a bias electric potential generated in the stage 14 by the bias electric power, and collide with the wafer W placed on the stage 14 at this time. Thereby, the helium ions are irradiated to the SOC film formed in the wafer W.

[0033] Further, a turbo molecular pump, a dry pump, or the like exhaust device 27 is connected to the bottom portion of the processing container 13 via an exhaust pipe 26. The exhaust device 27 maintains the processing space U at a predetermined pressure lower than the atmospheric pressure when the helium ions are irradiated to the SOC film.

[0034] In addition, a control section 28 is provided in the plasma processing device 12. The control section 28 is constituted by a computer having at least a CPU and a memory, and a program (program) for performing a prescribed film formation process, and deposition judgment of a deposit to be described later is recorded in the memory.

[0035] However, as described above, in the case where the SOC film is formed by performing heat treatment of the carbon-containing film at less than 500°C, it is difficult to sufficiently densify the SOC film, and it is necessary to further densify the SOC film by some method.

[0036] As a densification method of the SOC film, several methods can be considered, and the present applicant (hereinafter referred to as "the present applicant") has studied a method of densifying the SOC film by ion irradiation in view of the recent demand for low-temperature processing in the manufacturing process of semiconductor devices. Also, as a generation source of ions for ion irradiation, various processing gases have been tried, and as a result, it has been found that a gas of a light and small element is advantageous from the viewpoint of ensuring the modification depth (densification depth) in the SOC film and reducing the film shrinkage amount. Thus, as the processing gas used in the technology of the present application, helium gas is used.

[0037] In addition, in order to find conditions for forming an SOC film with high etching resistance by further densifying the SOC film using helium gas for ion irradiation, the present applicant has studied each condition at the time of ion irradiation through experiments.

[0038] First, the present applicant has conducted a study to find an appropriate size of the bias electric power at the time of ion irradiation. Specifically, first, a plurality of wafers as test pieces having SOC films formed by a low-temperature heat firing (heat firing at a temperature of the wafer of, for example, less than 500°C) were prepared. Then, in the plasma processing device 12, the SOC films of the respective wafers were subjected to irradiation of helium ions using bias electric powers of different sizes. Thereafter, each wafer on which helium ions were irradiated was subjected to RIE under conditions for etching a silicon oxide film, and the etching rate of the SOC film was measured. It can be considered that the lower the etching rate of the SOC film in this case, the higher the etching resistance of the SOC film is improved.

[0039] Figure 3A and Figure 3B is a graph showing each characteristic of the SOC film when the bias electric power at the time of irradiation of ions to the SOC film is changed, Figure 3A is the modification depth at the time of ion irradiation and the film shrinkage amount, Figure 3B is the etching rate based on RIE. Among them, each condition other than the bias electric power at the time of ion irradiation is that the internal pressure of the processing vessel 13 is 30 mTorr, the size of the high-frequency electric power for plasma generation is 500 W, and the flow rate of the helium gas supplied to the processing space U is 180 seem. In addition, the temperature of the wafer is 20°C, and the ion irradiation time is 10 seconds.

[0040] First, as shown in Figure 3A , when the bias electric power is increased, the modification depth of the SOC film is increased (refer to "●" in the graph). It can be understood from this that when the bias electric power is increased, the attraction of the helium ions is improved, the helium ions enter the deep part of the SOC film, and the modification layer is thickened. On the other hand, even if the bias electric power is increased, the film shrinkage amount is almost constant (refer to "O" in the graph). It can be understood from this that the etching amount of the SOC film by the helium ions is saturated after a certain degree of progress.

[0041] Furthermore, if Figure 3B As shown in the figure, when the bias power is increased, the etching rate of the SOC film decreases. This shows that the greater the bias power, the more the SOC film densifies and the higher the etching resistance. In addition, even when the bias power is 500W, the etching rate of the SOC film is lower than that of the conventional SOC film that is heated and fired at 500°C or above and not ion irradiated. Therefore, it can be seen that if the bias power during ion irradiation is set to 500W or above, the etching resistance is improved compared to the conventional SOC film.

[0042] In particular, it was confirmed that the etching rate further decreased when the bias power during ion irradiation was set to 3000 W or higher. On the other hand, even if the bias power was increased to strongly attract helium ions to the SOC film, the SOC film was not easily etched due to the extremely small mass of helium ions. Therefore, it was found that the bias power during ion irradiation was more preferably set to 3000 W or higher.

[0043] Next, the applicant conducted research to find the optimal pressure within the processing chamber 13 during ion irradiation. Specifically, they first prepared a number of test wafers, each containing a silicon oxide (SOC) film formed by relatively low-temperature heating and firing, and irradiated the wafers with helium ions in the plasma processing apparatus 12 while varying the internal pressure of the processing chamber 13. Subsequently, they performed RIE on each of the helium-irradiated wafers under conditions that allowed etching of the silicon oxide film, and measured the etch rate of the SOC film.

[0044] Figure 4 This graph shows the RIE etching rate of the SOC film as the internal pressure of processing vessel 13 during ion irradiation is varied. The conditions other than the internal pressure of processing vessel 13 during ion irradiation are: 500W of high-frequency power for plasma generation, 3000W of bias power, 20°C of wafer temperature, and 10 seconds of ion irradiation time. Furthermore, the internal pressure of processing vessel 13 was set to 30mTorr, 100mTorr, and 300mTorr, and the helium flow rate supplied to processing space U at each pressure was 180sccm, 360sccm, and 900sccm.

[0045] like Figure 4As shown in FIG. 1 , when the internal pressure of the processing container 13 is increased, the etching rate of the SOC film decreases. It can be seen that the higher the internal pressure of the processing container 13, the more the densification of the SOC film is advanced, and the higher the etching resistance. In addition, even when the internal pressure of the processing container 13 is 30 mTorr, the etching rate of the SOC film is lower than the etching rate of the conventional SOC film described above. Therefore, it can be seen that if the internal pressure of the processing container 13 during ion irradiation is set to 30 mTorr or more, the etching resistance is improved compared to the conventional SOC film. However, it can be seen that if the internal pressure of the processing container 13 is set to 100 mTorr or more, the etching rate of the SOC film is further reduced, so it is more preferable to set the internal pressure of the processing container 13 during ion irradiation to 100 mTorr or more.

[0046] Next, the applicant conducted research to find the optimal wafer temperature for ion irradiation. Specifically, they first prepared multiple test wafers, each containing a silicon oxide (SOC) film formed by relatively low-temperature heating and firing, and irradiated them with helium ions while varying the wafer temperature in a plasma processing apparatus 12. Subsequently, they performed RIE on each of the helium-irradiated wafers under conditions that allowed etching of the silicon oxide film, and measured the etch rate of the SOC film.

[0047] Figure 5 This graph shows the RIE etching rate of the SOC film as the wafer temperature during ion irradiation changes. The conditions other than the wafer temperature during ion irradiation are: the internal pressure of the processing container 13 is 300 mTorr, the high-frequency power for plasma generation is 0 W, and the bias power is 3000 W. Furthermore, the flow rate of helium gas supplied to the processing space U is 900 sccm, and the ion irradiation time is 10 seconds.

[0048] like Figure 5 As shown in Figure 2, if the wafer temperature is below 60°C, the etching rate of the SOC film irradiated with helium ions is significantly lower than the etching rate of the conventional SOC film described above. Therefore, it can be seen that if the wafer temperature during ion irradiation is kept below 60°C, the densification of the SOC film is promoted, and the etching resistance is improved compared to conventional SOC films. In particular, considering the recent demand for low-temperature processing in semiconductor device manufacturing processes, it is considered that a wafer temperature of 20°C is more preferable.

[0049] Next, the present applicant conducted a study to find a suitable ion irradiation time. Specifically, first, a plurality of wafers as test pieces were prepared, and irradiation of helium ions was performed in the plasma processing device 12, where the wafers had SOC films formed by heat baking with a low temperature, while varying the ion irradiation time. Thereafter, each of the wafers on which helium ions were irradiated was subjected to RIE under conditions capable of etching a silicon oxide film, and the etching rate of the SOC film was measured.

[0050] Figure 6 is a graph showing the etching rate of RIE of the SOC film when the ion irradiation time of the SOC film was changed. Here, each of the conditions other than the ion irradiation time was that the internal pressure of the processing vessel 13 was 300 mTorr, the magnitude of the high-frequency electric power for plasma generation was 0 W, the magnitude of the bias electric power was 3000 W, and the temperature of the wafer was 20°C. In addition, the flow rate of helium gas supplied to the processing space U was 900 seem.

[0051] As shown in Figure 6 , if the ion irradiation time was 120 seconds or less, the etching rate of the SOC film on which helium ions were irradiated was significantly reduced from the above-described etching rate of the conventional SOC film. Therefore, it was found that if the ion irradiation time was 120 seconds or less, the densification of the SOC film was promoted, and the etch resistance was improved compared to the conventional SOC film. On the other hand, it was expected that when the ion irradiation time was too short, the densification of the SOC film could not be sufficiently promoted, and the etch resistance would not be much improved, and thus the ion irradiation time was preferably 10 seconds or more in which the improvement in etch resistance could be confirmed.

[0052] Next, the present applicant conducted a study to find a suitable wafer temperature in heat baking of the carbon-containing film (hereinafter referred to as "baking temperature"). Specifically, first, a plurality of wafers as test pieces were prepared, and irradiation of helium ions was performed in the plasma processing device 12, where the wafers had SOC films formed by heat baking with a changed baking temperature. Thereafter, each of the wafers on which helium ions were irradiated was subjected to RIE under conditions capable of etching a silicon oxide film, and the etching rate of the SOC film was measured.

[0053] Figure 7 is a graph showing the etching rate of RIE of the SOC film when the baking temperature of the carbon-containing film was changed. Here, the etching conditions of RIE were the same for each of the test pieces.

[0054] As shown in Figure 7As shown, if the baking temperature is 110°C or higher and 300°C or lower, the etching rate of the SOC film to which the helium ions are irradiated is significantly lower than that of the conventional SOC film. Therefore, it is known that if the baking temperature is made to be any temperature between 110°C and 300°C, the densification of the SOC film before the ion irradiation is also advanced to some extent, and as a result of the subsequent ion irradiation, the densification of the SOC film is further advanced, and the etching resistance is improved as compared with the conventional SOC film.

[0055] wherein Figure 7 The etching rate of the conventional SOC film in which the baking temperature is 110°C in the above formula (1) indicates the etching rate of the SOC film on which the heating baking at 110°C is performed but on which the helium ions are not irradiated. Figure 7 The etching rate of the conventional SOC film in which the baking temperature is 300°C in the above formula (1) indicates the etching rate of the SOC film on which the heating baking at 300°C is performed but on which the helium ions are not irradiated.

[0056] In addition, in the study of the baking temperature, only the etching rates of the SOC film in which the baking temperature is 110°C and the SOC film in which the baking temperature is 300°C are confirmed, but it is considered that if the baking temperature is increased, the densification of the SOC film is further advanced, and the etching resistance is further improved. Therefore, in consideration of the recent requirement for low-temperature processing in the manufacturing process of semiconductor devices, it is considered that although the baking temperature is less than 500°C, which is lower than the conventional one, it is preferably set to a value close to 500°C.

[0057] According to the above research results, as the carbon film forming method of the present application, the following conditions are satisfied in the heating baking and the helium ion irradiation.

[0058] • The processing gas at the time of the ion irradiation is a single gas of helium gas;

[0059] • The bias electric power at the time of the ion irradiation is 500 W or higher;

[0060] • The internal pressure of the processing container 13 at the time of the ion irradiation is 100 mTorr or higher;

[0061] • The temperature of the wafer at the time of the ion irradiation is 60°C or lower and 20°C or higher;

[0062] • The ion irradiation time is 10 seconds or longer and 120 seconds or shorter;

[0063] • The baking temperature at the time of the heating baking is 110°C or higher and 300°C or lower.

[0064] Figure 8 is a flowchart showing the carbon film forming method of the present embodiment.

[0065] First, in the coating and developing device 11, a carbon-containing film is formed on the silicon oxide film of the wafer W by coating a SOC film raw material on the wafer W by spin coating (step S81). Thereafter, in the same coating and developing device 11, the wafer W on which the carbon-containing film is formed is heated, and the carbon-containing film is heated and fired to form a SOC film (step S82). The firing temperature at the time of heating and firing is set to an arbitrary temperature of 110°C or higher and 300°C or lower.

[0066] Next, the wafer W is carried out from the coating and developing device 11, and further carried into the inside of the processing vessel 13 of the plasma processing device 12 and placed on the placement table 14. Thereafter, the inside of the processing vessel 13 is depressurized to an arbitrary pressure of 100 mTorr or higher and 300 mTorr by the exhaust device 27, and a single gas of helium gas is supplied from the processing gas supply device 23 to the processing space U of the processing vessel 13. Further, the helium gas is excited by high-frequency electric power for plasma generation, and plasma is generated in the processing space U. Also, a bias electric power of 500 W or higher is supplied from the second high-frequency power supply 25 to the placement table 14, and ions in the plasma are attracted to the placement table 14, whereby helium ions are irradiated to the SOC film formed on the wafer W (step S83). At this time, the ion irradiation time is set to an arbitrary time of 10 seconds or longer and 120 seconds or shorter. Thereafter, the wafer W is carried out from the processing vessel 13, and the present processing is ended.

[0067] Figure 9 is a graph showing the results of comparing the etching rates of the SOC film formed by the carbon film forming method of the present embodiment with an amorphous carbon film (hereinafter referred to as "ACL film"). The ACL film is formed by firing and carbonizing a cured molded body of a specific resin, and thus is known to have a very dense structure and to have high etching resistance compared to the conventional SOC film formed by spin coating and heating and firing. In particular, there are ongoing studies on using the ACL film as a base layer of a photoresist film using extreme ultraviolet exposure in the manufacturing process of a logic semiconductor device.

[0068] In Figure 9In the previous examples, the etching rate of an SOC film is shown in which the carbon-containing film is heated and fired at a temperature above 500°C and the SOC film is not irradiated with ions. Example 1 shows the etching rate of an SOC film formed when the bias power during ion irradiation is 2000W, and the other conditions during ion irradiation and the firing temperature during heating and firing are within the range of the conditions of the carbon film forming method of the technology of the present invention. Example 2 shows the etching rate of an SOC film formed when the bias power during ion irradiation is 3000W, and the other conditions during ion irradiation and the firing temperature during heating and firing are within the range of the conditions of the carbon film forming method of the technology of the present invention. Comparative Example 1 shows the etching rate of an ACL film with a firing temperature of 480°C. Comparative Example 2 shows the etching rate of an ACL film with a firing temperature of 630°C. Comparative Example 3 shows the etching rate of an ACL film with a firing temperature of 150°C.

[0069] like Figure 9 As shown, it was confirmed that the etching rates of Examples 1 and 2 were lower than those of the conventional examples. In particular, the etching rate of Example 2 was 65% lower than that of the conventional example, resulting in significantly improved etching resistance. Furthermore, it was confirmed that the etching rates of Examples 1 and 2 were approximately equal to or even lower than those of Comparative Examples 1 to 3. In other words, it was confirmed that the SOC film formed using the carbon film formation method of the present invention has etching resistance equivalent to or higher than that of the ACL film.

[0070] Furthermore, the present applicant has confirmed the characteristics and composition of an SOC film formed by a carbon film forming method as the technique of the present invention. Figure 10 Graphs showing a comparison of various characteristics between an SOC film formed by the carbon film forming method of this embodiment and a conventional SOC film. Figure 10 2 shows the relative comparison of the values ​​of various characteristics of the SOC film formed by the carbon film forming method of this embodiment with the values ​​of various characteristics of the conventional SOC film.

[0071] like Figure 10 As shown in the graph, the complex refractive index n(633) at a wavelength of 633 nm, density, and hardness of the ion-irradiated SOC film formed by the carbon film formation method of the present invention all show values ​​significantly higher than those of conventional SOC films. This confirms that the ion-irradiated SOC film formed by the carbon film formation method of the present invention (hereinafter referred to as the "ion-irradiated SOC film") has significantly improved densification compared to conventional SOC films.

[0072] In addition, the conventional SOC film and the ion-irradiated SOC film were subjected to spectral analysis, and it was confirmed that the intensity distribution of the conventional SOC film and the intensity distribution of the ion-irradiated SOC film were greatly different. That is, by the carbon film forming method as the technology of the present application, not only densification of the SOC film was promoted, but also it was confirmed that the film itself was modified. In particular, it was confirmed that the intensity distribution of the ion-irradiated SOC film was similar to the intensity distribution of a diamond-like carbon film which is known for high intensity and high density.

[0073] According to the present embodiment, after the carbon-containing film is subjected to heat baking at a low temperature of less than 500°C to form the SOC film, the SOC film is irradiated with helium ions, whereby densification of the SOC film is promoted. Thus, the SOC film having high etching resistance can be formed.

[0074] The above describes the preferred embodiment of the present application, but the present application is not limited to the above-described embodiment, and various modifications and changes can be made within the scope of the gist thereof.

[0075] For example, the carbon film forming apparatus 10 which executes the carbon film forming method as the technology of the present application is composed of two apparatuses, the coating and developing apparatus 11 and the plasma processing apparatus 12, but the coating and developing apparatus 11 can include each component of the plasma processing apparatus 12. In this case, the formation of the carbon-containing film based on spin coating, the heat baking of the carbon-containing film, and the irradiation of the SOC film with helium ions can be performed by the same apparatus, and the transport distance of the wafer W can be shortened, so that the throughput can be improved.

[0076] This application claims priority based on Japanese Patent Application No. 2023-041734 filed on March 16, 2023, and the entire contents described in the Japanese Patent Application are incorporated herein by reference.

[0077] Explanation of Reference Numerals

[0078] 10 Carbon film forming apparatus

[0079] 11 Coating and developing apparatus

[0080] 12 Plasma processing apparatus

[0081] W Wafer

Claims

1. A method for forming a carbon film, characterized in that: A carbon film raw material is applied to a substrate by spin coating to form a carbon-containing film on the substrate. The carbon-containing film is heated and fired to form a carbon film. The carbon film is then irradiated with helium ions.

2. The carbon film forming method according to claim 1, wherein: The temperature of the substrate during the heating and firing is maintained at less than 500°C.

3. The carbon film forming method according to claim 1, wherein: The temperature of the substrate during the helium ion irradiation is maintained at 60° C. or less.

4. The carbon film forming method according to claim 3, wherein: The temperature of the substrate during the helium ion irradiation is maintained at 20° C. or higher.

5. The carbon film forming method according to claim 2, wherein: The temperature of the substrate during the heating and firing is maintained at 300° C. or less.

6. The carbon film forming method according to claim 5, wherein: The temperature of the substrate during the heating and firing is maintained at 110° C. or higher.

7. The carbon film forming method according to claim 1, wherein: The magnitude of the high-frequency electric power for attracting ions, which is supplied to the electrode on which the substrate is placed, is set to 500 W or more when irradiating the helium ions.

8. The carbon film forming method according to claim 7, wherein: The magnitude of the high-frequency electric power for attracting the ions supplied to the electrode during the irradiation with the helium ions is set to 3000 W or more.

9. The carbon film forming method according to claim 1, wherein: The irradiation time of the helium ions to the substrate is 10 seconds or longer.

10. The carbon film forming method according to claim 9, wherein: The irradiation time of the helium ions to the substrate is 120 seconds or less.

11. The carbon film forming method according to claim 1, wherein: During the helium ion irradiation, the internal pressure of the processing container housing the substrate is maintained at 100 mTorr or higher.

12. A carbon film forming apparatus, characterized in that: include: a spin coating unit capable of coating a carbon film raw material on a substrate by a spin coating method to form a carbon-containing film on the substrate; a heating and firing unit capable of heating and firing the carbon-containing film to form a carbon film; and The ion irradiation unit is capable of irradiating the carbon film with helium ions.

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