Film deposition method and film deposition apparatus

Abstract

Even at low temperatures, a carbon-based film is selectively and perpendicularly deposited on the top of the pattern. [Solution] When a substrate having a pattern is placed inside a processing chamber, a film-forming gas is supplied inside the processing chamber, and plasma is generated from the film-forming gas by high-frequency power to perform a film-forming process on the substrate, the film-forming gas contains multiple types of hydrocarbon gases and noble gases, and when multiple types of hydrocarbon gases are excited and turned into plasma, the composition of the active species generated from each hydrocarbon gas is different.

Description

Technical Field

[0001] The present disclosure relates to a film forming method and a film forming apparatus.

Background Art

[0002] As a method for manufacturing a hydrogenated amorphous carbon thin film, a film forming method using plasma generated from a hydrocarbon gas is known. In this film forming method, after reducing the pressure of the vacuum layer of the CVD apparatus, a mixed gas composed of ethylene (C2H4) gas and methane (CH4) gas, or ethylene gas and acetylene (C2H2) gas, diluted with an appropriate amount of hydrogen gas, is introduced into the vacuum chamber. Then, while rotating a susceptor on which a substrate is placed inside the vacuum layer, high-frequency power of 13.56 MHz is applied from a high-frequency power source between an electrode and the susceptor at 20 W to 300 W. At this time, plasma is generated from the mixed gas, and a hydrogenated amorphous carbon thin film is formed on the substrate (see, for example, Patent Document 1). However, in the film forming method described in Patent Document 1, only a carbon-based film that entirely covers the surface of the substrate is formed.

[0003] On the other hand, in the manufacture of three-dimensional NAND-type flash memories, a technique for increasing the substantial thickness of a mask film formed on the surface of a substrate when forming deep trenches or deep holes by etching has been developed. As this technique, a film forming method for selectively and vertically forming an amorphous carbon-based film on the top of a pattern (for example, the top of a trench) formed in a mask film has been proposed by the present applicant. In this film forming method, acetylene (C2H2) gas is used as the hydrocarbon gas in the film forming gas, and further, hydrogen (H2) gas is added to the film forming gas. Then, the amorphous carbon-based film formed on the top of the pattern by plasma generated from acetylene gas is etched by hydrogen radicals so as to grow vertically without overhanging the pattern. In particular, since the etching by hydrogen radicals becomes stronger as the temperature of the substrate is higher, the film forming method using a film forming gas containing acetylene gas and hydrogen gas is executed after raising the temperature of the substrate to, for example, around 350°C.

Prior Art Documents

[0004] [Patent Document 1] Japanese Patent Application Publication No. 1-301506 [Overview of the project] [Problems that the invention aims to solve]

[0005] The technology described herein allows for the selective and perpendicular deposition of a carbon-based film on the top of a pattern, even when the substrate is at a low temperature. [Means for solving the problem]

[0006] One aspect of the technology described herein is a film deposition method comprising housing a patterned substrate inside a processing chamber, supplying a film deposition gas to the processing chamber, and generating plasma from the film deposition gas using high-frequency power to perform a film deposition process on the substrate, wherein the film deposition gas includes a plurality of types of hydrocarbon gases and noble gases, and when the plurality of types of hydrocarbon gases are excited and generated into plasma, the composition of the active species generated from each hydrocarbon gas is different. [Effects of the Invention]

[0007] According to the technology described herein, a carbon-based film can be selectively and perpendicularly deposited on the top of a pattern, even when the substrate is at a low temperature. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic cross-sectional view showing the configuration of a film deposition apparatus according to one embodiment of the technology disclosed herein. [Figure 2] This is a partially enlarged cross-sectional view showing the deposition morphology of carbon-based films when the type of hydrocarbon gas contained in the deposition gas is changed. [Figure 3] This is a partially enlarged cross-sectional view showing the film formation morphology of a carbon-based film when a film formation process was carried out using a film formation gas containing ethylene gas and acetylene gas as hydrocarbon gases. [Figure 4]This is a partially enlarged cross-sectional view showing the film deposition morphology of a carbon-based film when the trench aspect ratio is low and the film deposition process is performed using a deposition gas containing only ethylene gas as the hydrocarbon gas. [Modes for carrying out the invention]

[0009] In recent years, with the further miniaturization of wiring in semiconductor devices, it has become necessary to form trenches with widths of several nanometers to several tens of nanometers in mask films. To meet this requirement, patterns are formed on mask films using EUV (Extreme Ultraviolet) light with a wavelength of 13.5 nm. Chemically amplified resists are used as the material for such mask films, but the heat resistance temperature of chemically amplified resists is low, for example, around 200°C.

[0010] However, etching of carbon-based films by hydrogen radicals becomes considerably weaker below 200°C, making it difficult to shape the carbon-based film deposited at the top of the pattern. As a result, even with the addition of hydrogen gas, the carbon-based film grows overhanging and blocking the trenches, which can prevent the shape of the pattern formed on the mask film from being reflected in the subsequent etching of the underlying film covered by the mask film.

[0011] In contrast, the technology described herein controls the shape of a carbon-based film by using a film-forming gas containing multiple types of hydrocarbon gases, without adding hydrogen gas to the film-forming gas.

[0012] Hereinafter, an embodiment of the technology according to this disclosure will be described with reference to the drawings. Figure 1 is a schematic cross-sectional view showing the configuration of a film deposition apparatus according to an embodiment of the technology according to this disclosure. This film deposition apparatus is a capacitively coupled plasma processing apparatus that performs film deposition by generating plasma from a film deposition gas.

[0013] In Figure 1, the film deposition apparatus 10 is equipped with a roughly cylindrical metal chamber 11 (processing chamber), and the chamber 11 is grounded. A wafer W (substrate) is housed inside the chamber 11, and a mounting stage 12 on which the wafer W is placed is also positioned.

[0014] The mounting table 12 is made of an insulator and includes a grounded lower electrode (not shown). Alternatively, the mounting table 12 may be made of metal and function as the lower electrode. A heater and a coolant passage (both not shown) are embedded inside the mounting table 12. The heater generates heat using externally supplied electricity to heat the placed wafer W, and the coolant passage circulates a coolant supplied from the outside to cool the placed wafer W. To improve heat transfer between the mounting table 12 and the wafer W, a heat transfer gas may be supplied between the mounting table 12 and the wafer W. Furthermore, multiple lifting pins (not shown) are inserted into the mounting table 12 so as to be retractable into its upper surface, and these lifting pins move up and down by a lifting mechanism (not shown) to transfer the wafer W to and from the mounting table 12.

[0015] An opening is formed in the upper part of the chamber 11, and a shower head 13 is fitted into this opening via an insulating member 14 so as to face the mounting base 12. The shower head 13 is made of a cylindrical metal member and functions as an upper electrode. Note that only a part of the shower head 13 may be made of metal, and this metal part may function as the upper electrode. The shower head 13 has a shower body 15 with an opening at the bottom and a shower plate 16 provided to close the opening of the shower body 15, and the internal space between them functions as a gas diffusion space. In addition, the shower plate 16 has a plurality of gas discharge holes 17 that penetrate the shower plate 16 in the thickness direction. Furthermore, a gas introduction hole 18 is formed in the shower head 13, and the film-forming gas supplied from the gas supply unit 19 (described later) is introduced into the gas diffusion space via the gas introduction hole 18. The film-forming gas introduced into the gas diffusion space then diffuses and is discharged from each gas discharge hole 17 into the space S between the shower head 13 and the mounting base 12 inside the chamber 11 (hereinafter referred to as the "processing space").

[0016] The film deposition apparatus 10 further includes a gas supply unit 19. The gas supply unit 19 supplies multiple gases, such as a film deposition gas and a purge gas. The gas supply unit 19 has multiple gas sources, a flow rate controller, and on / off valves, and adjusts the flow rate of each gas according to the processing. In this embodiment, a mixed gas containing hydrocarbon gas and noble gas is used as the film deposition gas supplied by the gas supply unit 19.

[0017] A high-frequency power supply 21 is connected to the shower head 13 via a power supply line 20. The high-frequency power supply 21 applies a high-frequency voltage with a frequency of 100kHz to 220MHz, for example, 450kHz, to the shower head 13.

[0018] A matching circuit 22 is connected downstream of the high-frequency power supply 21 in the power supply line 20. The matching circuit 22 matches the load impedance to the internal (or output) impedance of the high-frequency power supply 21. Furthermore, a circuit that limits the applied voltage, such as a clamp circuit 23, is provided downstream of the matching circuit 22 between the high-frequency power supply 21 and the showerhead 13 in the power supply line 20.

[0019] The clamp circuit 23 includes a capacitor 24 located downstream of the matching circuit 22, and a grounding circuit 26 that branches off from the power supply line 20 downstream of the capacitor 24 and is grounded via a diode 25. The capacitor 24 is one that has sufficient capacitance to reduce the impedance when viewed from the high-frequency power supply 21.

[0020] When the high-frequency power supply 21 outputs a positive voltage, the clamping circuit 23 allows a high-frequency current to pass through the diode 25 and flow to the ground side by virtue of the power storage function of the capacitor 24 and the rectifying function of the diode 25 in the grounding circuit 26. At this time, the high-frequency power output by the high-frequency power supply 21 is stored in the capacitor 24. As a result, the positive voltage among the high-frequency voltages applied to the shower head 13 is suppressed. On the other hand, when the high-frequency power supply 21 outputs a negative voltage, since the diode 25 does not allow a high-frequency current to pass through, the high-frequency current does not flow to the ground side via the grounding circuit 26. And at this time, the power output by the high-frequency power supply 21 and the power stored in the capacitor 24 are supplied to the shower head 13.

[0021] Note that in the film forming apparatus 10, although the clamping circuit 23 is provided as a circuit for suppressing the positive voltage of the high-frequency voltage, another form of circuit capable of suppressing the positive voltage of the high-frequency voltage may be provided instead of the clamping circuit 23. Further, in the clamping circuit 23, instead of the capacitor 24, the blocking capacitor of the matching unit 22 may store the high-frequency power output by the high-frequency power supply 21. In this case, it is possible to eliminate the need to provide the capacitor 24 in the clamping circuit 23.

[0022] Incidentally, in a capacitively coupled plasma processing apparatus, when the lower electrode is grounded, the plasma potential largely depends on the potential of the upper electrode. And in the film forming apparatus 10, since the positive voltage is suppressed by the clamping circuit 23, the voltage of the upper electrode does not swing greatly to the positive side. As a result, the film forming apparatus 10 can reduce the plasma potential. Also, ions in the plasma are accelerated by the sheath voltage and flow into the wafer W. However, when the plasma potential is reduced, the absolute value of the sheath voltage (the difference between the plasma potential and the potential of the wafer W (mounting table 12)) generated in the processing space S becomes small, so the ions are not accelerated as much. As a result, in the film forming apparatus 10, the ion energy imparted from the plasma to the wafer W mounted on the mounting table 12 is reduced.

[0023] Furthermore, the film deposition apparatus 10 is provided with an exhaust port 27 at the bottom of the chamber 11, and an exhaust device 29 is connected to the exhaust port 27 via an exhaust pipe 28. The exhaust device 29 has an automatic pressure control valve and a vacuum pump, and the exhaust device 29 evacuates the inside of the chamber 11 to reduce the pressure and maintains the inside of the chamber 11 at a desired vacuum level. In addition, an inlet / outlet (not shown) for loading and unloading wafers W is provided on the side wall of the chamber 11, and this inlet / outlet is opened and closed by a gate valve (not shown).

[0024] Furthermore, the film deposition apparatus 10 is equipped with a control unit 30, which controls the operation of each component of the film deposition apparatus 10. The control unit 30 is a computer equipped with a processor, memory, input device, display device, and signal input / output interface, and the memory of the control unit 30 stores a control program and recipe data. When the film deposition process is performed in the film deposition apparatus 10, the processor of the control unit 30 executes the corresponding control program and controls the operation of each component of the film deposition apparatus 10 according to the recipe data.

[0025] Specifically, the control unit 30 controls the gas supply unit 19 and the exhaust device 29 to adjust the pressure inside the chamber 11, and controls the high-frequency power supply 21 to apply a high-frequency voltage to the shower head 13. The control unit 30 also controls the gas supply unit 19 to diffuse and introduce the film-forming gas into the chamber 11. At this time, the application of a high-frequency voltage to the shower head 13 generates an electric field in the processing space S, exciting the film-forming gas and turning it into plasma, generating active species. These active species then perform the film-forming process on the wafer W.

[0026] Incidentally, when depositing a carbon-based film with vertical growth at the top of a pattern formed on a mask film made of a chemically amplified resist, the heat resistance temperature of the chemically amplified resist is about 200°C, so it is necessary to maintain the wafer W temperature below 200°C. Therefore, the applicant used a film deposition apparatus 10 to confirm the film deposition morphology of the carbon-based film when the type of hydrocarbon gas contained in the film deposition gas was changed while maintaining the wafer W temperature (specifically, the temperature of the mounting stage 14) at 200°C.

[0027] Figure 2 is a partially enlarged cross-sectional view showing the film formation morphology of a carbon-based film when the type of hydrocarbon gas contained in the film formation gas is changed. In Figure 2, on a wafer W, a mask film 32 made of, for example, a chemically amplified resist is formed on the surface of a substrate 31 made of silicon (Si), and a pattern, for example, groove-shaped trenches 33, is formed on the mask film 32. The trenches 33 penetrate the mask film 32, and the substrate 31 is exposed at the bottom of the trenches 33 (Figures 2(A) to 2(C)). In this embodiment, the top of the mask film 32 between two adjacent trenches 33 will be referred to as the "top of the trench 33" below.

[0028] First, the applicant performed a film deposition process on a wafer W using a film deposition gas containing only acetylene gas as the hydrocarbon gas in a film deposition apparatus 10 (hereinafter referred to as "when acetylene gas is used"). In addition to acetylene gas, the film deposition gas also contained argon (Ar) gas as a noble gas. At this time, the carbon-based film 34 was not deposited selectively and perpendicularly on the top of the trench 33, but rather overhanged toward the trench 33, thus sealing the trench 33. Furthermore, a carbon-based film 34 with a certain thickness (for example, a thickness of about 7.6 nm) was also deposited on the bottom of the trench 33, and a carbon-based film 34 was also deposited on the sides of the trench 33 (Figure 2(A)).

[0029] Next, the applicant performed a film deposition process on a wafer W using a film deposition gas in a film deposition apparatus 10 that contained only ethylene gas as the hydrocarbon gas and only argon gas as the noble gas (hereinafter referred to as "when ethylene gas was used"). At this time, a carbon-based film 34 tapered selectively and vertically was deposited on the top of the trench 33. Although a small amount of carbon-based film 34 (for example, with a thickness of about 1.7 nm) was deposited on the bottom of the trench 33, no carbon-based film 34 was formed on the sides of the trench 33 (Figure 2(B)).

[0030] Furthermore, the applicant performed a film deposition process on a wafer W using a film deposition gas in a film deposition apparatus 10 that contained only propylene (C3H6) gas as the hydrocarbon gas and only argon gas as the noble gas (hereinafter referred to as "when propylene gas is used"). In this case, a carbon-based film 34 was deposited on the top of the trench 33, but the carbon-based film 34 did not block the trench 33. In addition, a carbon-based film 34 with some thickness (for example, a thickness of about 10.3 nm) was deposited on the bottom of the trench 33, and a carbon-based film 34 with some thickness (for example, a thickness of about 4.3 nm) was also deposited on the sides of the trench 33 (Figure 2(C)).

[0031] As shown in Figures 2(A) to 2(C), it was found that the deposition morphology of the carbon-based film 34 differed depending on the type of hydrocarbon gas used. For example, when acetylene gas or propylene gas was used, the carbon-based film 34 was deposited not only on the top of the trench 33 but also on the bottom and sides of the trench 33. Therefore, it was found that acetylene gas and propylene gas exhibit conformal properties during the deposition of the carbon-based film 34. On the other hand, when ethylene gas was used, almost no carbon-based film 34 was deposited on the bottom or sides of the trench 33, and the carbon-based film 34 was selectively deposited only on the top of the trench 33. Therefore, it was found that ethylene gas exhibits non-conformal properties during the deposition of the carbon-based film 34. Furthermore, regarding the amount of film deposited, the amount was highest when acetylene gas was used and lowest when ethylene gas was used.

[0032] Therefore, in order to investigate the factors that cause the deposition morphology of the carbon-based film 34 to differ depending on the type of hydrocarbon gas, we used Chemkin, simulation software from ANSYS, to identify the chemical species generated when each deposition gas is plasma-activated.

[0033] First, when acetylene gas was used, it was confirmed that a large amount of carbon-based reactive species such as C and C2, and hydrocarbon-based reactive species with a low hydrogen element ratio were generated. Furthermore, when ethylene gas was used, it was confirmed that a large amount of H2 reactive species (hydrogen radicals) and hydrocarbon-based reactive species were generated. Finally, when propylene gas was used, it was confirmed that a large amount of hydrocarbon-based reactive species with a high hydrogen element ratio were generated.

[0034] The results of this simulation revealed that the composition of active species generated from the film-forming gas differs depending on the type of hydrocarbon gas used. Furthermore, the applicant hypothesized the following mechanism as to why the composition of active species differs in response to changes in the type of hydrocarbon gas.

[0035] In other words, acetylene gas contains a triple bond between carbon atoms, and the bond between carbon atoms and hydrogen atoms dissociates easily, resulting in the generation of many carbon-based reactive species. Also, in acetylene gas, the elemental ratio of hydrogen to carbon is inherently low, so the elemental ratio of hydrogen in the resulting hydrocarbon reactive species is also low. Although ethylene gas contains a double bond between carbon atoms, the elemental ratio of hydrogen to carbon is inherently high, resulting in the generation of many hydrogen radicals and hydrocarbon reactive species. In propylene gas, a methyl (CH3) group is bonded to the carbon atom, so the methyl group dissociates easily, resulting in a high elemental ratio of hydrogen in the resulting hydrocarbon reactive species.

[0036] Incidentally, with hydrocarbon-based active species, the higher the elemental ratio of hydrogen, the lower the adhesion coefficient to carbon. When hydrocarbon-based active species with a low adhesion coefficient enter the trench 33, less adheres near the opening of the trench 33 (i.e., the top), and a relatively large amount of hydrocarbon-based active species reaches the bottom of the trench 33. As a result, a carbon-based film 34 is formed not only on the top of the trench 33, but also on the bottom and sides of the trench 33. On the other hand, with hydrocarbon-based active species, the lower the elemental ratio of hydrogen, the higher the adhesion coefficient to carbon. When hydrocarbon-based active species with a high adhesion coefficient enter the trench 33, most of them adhere near the opening (top) of the trench 33. Also, because carbon-based active species have a very high adhesion coefficient, when carbon-based active species enter the trench 33, most of them also adhere near the opening (top) of the trench 33.

[0037] When acetylene gas is used, as described above, a large number of carbon-based active species and hydrocarbon-based active species with a low hydrogen element ratio are generated. However, because the adhesion coefficient of these active species is high, most of them adhere near the opening (top) of the trench 33. Furthermore, the carbon-based film 34 generated from hydrocarbon-based active species with a low hydrogen element ratio has a high-density film quality, so even if hydrogen radicals are generated, etching by these hydrogen radicals is difficult to carry out. As a result, the carbon-based film 34 is formed so as to overhang the trench 33, sealing the trench 33. In addition, because the adhesion coefficient of the active species generated from acetylene gas is high, these active species that do not adhere near the opening of the trench 33 and enter the interior of the trench 33 adhere to the bottom and sides of the trench 33, and the carbon-based film 34 is also formed on the bottom and sides of the trench 33. Thus, acetylene gas forms a carbon-based film 34 not only on the top of the trench 33 but also on the bottom and sides of the trench 33, and therefore it is a hydrocarbon gas that exhibits conformation during film formation.

[0038] Furthermore, when ethylene gas is used, as described above, hydrocarbon-based active species are generated, but since most of these hydrocarbon-based active species are stable acetylene-based active species, a large amount of hydrocarbon-based active species do not adhere to the mask film 32. In addition, since a large amount of hydrogen radicals are generated simultaneously with the hydrocarbon-based active species, the carbon-based film 34 attached to the bottom and sides of the trench 33 is etched by the hydrogen radicals. As a result, almost no carbon-based film 34 is formed on the bottom and sides of the trench 33, and the carbon-based film 34 is mainly formed selectively and perpendicularly on the top of the trench 33. The carbon-based film 34 formed on the top of the trench 33 is also etched by hydrogen radicals, resulting in a tapered shape. Thus, ethylene gas does not form a carbon-based film 34 on the bottom or sides of the trench 33, but mainly forms a carbon-based film 34 on the top of the trench 33, and therefore falls under the category of hydrocarbon gases that exhibit non-conforming properties during film formation.

[0039] Furthermore, when propylene gas is used, as mentioned above, a large number of hydrocarbon-based active species with a high hydrogen element ratio are generated. However, because the adhesion coefficient of these hydrocarbon-based active species is low, they adhere not only to the top of the trench 33 but also to the bottom and sides of the trench 33. As a result, a carbon-based film 34 is formed not only on the top of the trench 33 but also on the bottom and sides of the trench 33. Thus, propylene gas is a hydrocarbon gas that exhibits conformation during film formation because it causes a carbon-based film 34 to be formed not only on the top of the trench 33 but also on the bottom and sides of the trench 33.

[0040] In the manufacturing of three-dimensional NAND flash memory, it is considered to increase the effective thickness of the mask film 32 by depositing a carbon-based film 34 in order to form deep trenches, etc. However, if the trenches 33 are blocked, or if the carbon-based film 34 is deposited on the bottom or side walls of the trenches 33, the shape of the trenches 33 cannot be accurately reflected in the layer to be etched. Therefore, in order to increase the effective thickness of the mask film 32 by depositing a carbon-based film 34, it is considered preferable to use ethylene gas, which exhibits non-conforming properties during film formation, as the hydrocarbon gas in the film formation gas.

[0041] However, when ethylene gas is used, the amount of carbon-based film 34 deposited is small due to the effects of etching by hydrogen radicals and the effects of acetylene active species generated from ethylene gas, and the carbon-based film 34 exhibits a tapered shape. Therefore, even if only ethylene gas is included as the hydrocarbon gas in the film deposition gas, it is difficult to impart sufficient thickness to the mask film 32 with the carbon-based film 34 in order to form deep trenches, etc.

[0042] Therefore, the applicant considered including ethylene gas and other gases as hydrocarbon gases in the film-forming gas to suppress the effects of etching by hydrogen radicals and the effects of acetylene active species, thereby imparting sufficient thickness to the mask film 32. Specifically, the applicant considered including acetylene gas in addition to ethylene gas as hydrocarbon gases in the film-forming gas, and performed the film-forming process using this film-forming gas in the film-forming apparatus 10. At this time, the temperature of the wafer W (specifically, the temperature of the mounting stage 14) was maintained at 200°C, and the flow rates of acetylene gas / ethylene gas / argon gas in the film-forming gas were set to 3 / 15 / 150 (all in units of sccm). In addition, a high-frequency voltage of 450kHz was applied to the shower head 13 with an output of 100W, and the pressure inside the chamber 11 was set to 2 Torr.

[0043] Figure 3 is a partially enlarged cross-sectional view showing the deposition morphology of a carbon-based film when a film deposition process was performed using a deposition gas containing ethylene gas and acetylene gas as hydrocarbon gases. In this case, as shown in Figure 3, a carbon-based film 34 was selectively and perpendicularly deposited on the top of the trench 33, but the carbon-based film 34 did not exhibit a tapered shape as in the case where ethylene gas was used. Furthermore, the amount of film deposited was sufficient to impart a sufficient thickness to the mask film 32 with the carbon-based film 34. Specifically, the thickness of the carbon-based film 34 at the top of the trench 33 was approximately 54.9 nm, which was almost the same as the thickness of the carbon-based film 34 at the top of the trench 33 when acetylene gas was used (approximately 53.2 nm). In addition, although no carbon-based film 34 was formed on the sides of the trench 33, a carbon-based film 34 with a certain thickness (for example, a thickness of approximately 4.6 nm) was deposited on the bottom of the trench 33. However, the amount of carbon-based film 34 deposited on the bottom was such that it could be sufficiently removed by anisotropic etching, for example, etching using plasma generated from oxygen (O2) gas, which is performed as a post-etching process after the film deposition treatment.

[0044] The mechanism by which the carbon-based film 34 shown in Figure 3 is formed is as follows. Specifically, many carbon-based active species and hydrocarbon-based active species with a low hydrogen element ratio generated from acetylene gas adhere near the opening of the trench 33, increasing the amount of carbon-based film 34 formed by hydrocarbon-based active species generated from ethylene gas. On the other hand, hydrogen radicals generated from ethylene gas moderately etch the carbon-based film 34 formed at the top of the trench 33, preventing the carbon-based film 34 from overhanging toward the trench 33. Furthermore, even if carbon-based active species and hydrocarbon-based active species with a low hydrogen element ratio generated from acetylene gas enter the interior of the trench 33 and adhere to the bottom or sides of the trench 33, they are etched by hydrogen radicals generated from ethylene gas. As a result, a non-tapering carbon-based film 34 is formed selectively and perpendicularly at the top of the trench 33.

[0045] The film deposition method according to this embodiment is based on this finding. Specifically, when performing the film deposition process, the deposition gas contains ethylene gas, which exhibits non-conformity during film deposition, and acetylene gas, which exhibits conformity during film deposition, as hydrocarbon gases. This appropriately balances the non-conformity and conformity of multiple types of hydrocarbon gases, making it possible to deposit a carbon-based film 34 that selectively and vertically does not taper at the top of the trench 33, even when the wafer W is at a low temperature, for example, below 200°C. In this case, as shown in Figure 3, the carbon-based film 34 (carbon-containing residue) is deposited and remains at the bottom of the trench 33, so anisotropic etching is performed on the wafer W after the film deposition process to remove the carbon-based film 34 at the bottom.

[0046] Furthermore, in the example shown in Figure 3, acetylene gas was used as the hydrocarbon gas that exhibits conformation during film formation, but propylene gas, which exhibits conformation during film formation, may be used instead of acetylene gas. Incidentally, as shown in Figure 4, when the aspect ratio of the trench 33 is low, if only ethylene gas is included as the hydrocarbon gas, a carbon-based film 34 with a certain thickness (for example, a thickness of about 3.6 nm) is selectively formed on the top of the trench 33. Also, the carbon-based film 34 was not formed on the bottom or sides of the trench 33 (Figure 2(B)). However, even in this case, it is difficult to impart sufficient thickness to the mask film 32 with the carbon-based film 34 in order to form deep trenches, etc.

[0047] Therefore, it is necessary to include a hydrocarbon gas that deposits a larger amount of carbon-based film 34 than ethylene gas to provide sufficient thickness to the mask film 32. In the example shown in Figure 3, the depth of the trench 33 was approximately 95.6 nm, whereas in the example shown in Figure 4, the depth of the trench 33 was approximately 23.5 nm, indicating that the trench 33 is very shallow. Consequently, if acetylene gas, which deposits a large amount of carbon-based film 34, is included as the hydrocarbon gas, there is a risk that the trench 33 will be completely filled with the carbon-based film 34. Therefore, it is preferable to include propylene gas, which deposits less carbon-based film 34 than acetylene gas, as the deposition gas. This increases the amount of carbon-based film 34 deposited at the top of the trench 33 without completely filling the trench 33, thereby providing sufficient thickness to the mask film 32. At this time, a carbon-based film 34 with a certain thickness is formed on the bottom and sides of the trench 33 due to the propylene gas, but these carbon-based films 34 are removed by performing anisotropic etching on the wafer W after the film formation process is completed.

[0048] Furthermore, as mentioned above, ethylene gas, acetylene gas, and propylene gas have different compositions of active species generated when they are plasma-generated. Therefore, the film deposition method according to this embodiment can be said to involve including multiple types of hydrocarbon gases, each with a different composition of active species generated when plasma-generated, in the film deposition gas when performing the film deposition process.

[0049] Furthermore, in this embodiment, a mask film made of a chemically amplified resist is used as the mask film 32. Therefore, the film deposition method according to this embodiment is performed while maintaining the temperature of the wafer W (specifically, the temperature of the mounting stage 14) at 200°C or lower. However, if a mask film with higher heat resistance than a chemically amplified resist is used as the mask film 32, the film deposition method according to this embodiment may be performed while maintaining the temperature of the wafer W (specifically, the temperature of the mounting stage 14) at a temperature higher than 200°C.

[0050] Furthermore, in the film-forming method according to this embodiment, the film-forming gas includes not only hydrocarbon gases that exhibit conformation during film formation and hydrocarbon gases that exhibit non-conformation during film formation, but also noble gases, such as argon gas. In the following, hydrocarbon gases that exhibit conformation during film formation will be referred to as "conformation hydrocarbon gases," and hydrocarbon gases that exhibit non-conformation during film formation will be referred to as "non-conformation hydrocarbon gases."

[0051] While preferred embodiments of this disclosure have been described above, this disclosure is not limited to the embodiments described above, and various modifications and changes are possible within the scope of its essence.

[0052] In the embodiment described above, acetylene gas and propylene gas were used as conforming hydrocarbon gases, but the conforming hydrocarbon gas is not limited to these gases; for example, methane (CH4) gas may also be used. Since methane gas, like propylene gas, has methyl groups, it can form a carbon-based film 34 not only on the top of the trench 33 but also on the bottom and sides of the trench 33 without blocking it, just like propylene gas. Therefore, it is mainly used as a substitute for propylene gas.

[0053] Furthermore, in the embodiment described above, the film-forming gas contained one type of conforming hydrocarbon gas, but the film-forming gas may contain multiple types of conforming hydrocarbon gases.

[0054] Furthermore, in the embodiment described above, the film-forming gas contained both non-conformal hydrocarbon gas and conformal hydrocarbon gas as hydrocarbon gases. That is, during the film-forming process, both non-conformal hydrocarbon gas and conformal hydrocarbon gas were simultaneously supplied into the chamber 11.

[0055] However, in the film formation process, non-conformal hydrocarbon gas and conformal hydrocarbon gas may be supplied alternately to the chamber 11. Alternatively, in the film formation process, only non-conformal hydrocarbon gas and a mixed gas of non-conformal hydrocarbon gas and conformal hydrocarbon gas may be supplied alternately to the chamber 11. Furthermore, in the film formation process, only conformal hydrocarbon gas and a mixed gas of non-conformal hydrocarbon gas and conformal hydrocarbon gas may be supplied alternately to the chamber 11. In addition, in the film formation process, the mixing ratio of non-conformal hydrocarbon gas and conformal hydrocarbon gas may be varied while supplying them to the chamber 11. [Explanation of Symbols]

[0056] W wafer 10 Film deposition equipment 11 Chambers 32 Mask film 33 Trench 34 Carbon-based membrane

Claims

1. A film deposition method comprising: housing a substrate having a pattern inside a processing chamber; supplying a film deposition gas to the processing chamber; and generating plasma from the film deposition gas using high-frequency power to perform a film deposition process on the substrate, The aforementioned film-forming gas includes multiple types of hydrocarbon gases and noble gases. A film deposition method wherein, when the aforementioned multiple types of hydrocarbon gases are excited and converted into plasma, the composition of the active species generated from each hydrocarbon gas is different.

2. The film formation method according to claim 1, wherein the film formation gas contains a hydrocarbon gas that exhibits conformation during film formation and a hydrocarbon gas that exhibits non-conformation during film formation.

3. The film deposition method according to claim 2, wherein the hydrocarbon plasma generated from the non-conformable hydrocarbon gas during film deposition mainly deposits a carbon-based film on the top of the pattern.

4. The hydrocarbon gas that exhibits non-conformity during film formation is ethylene (C ２ H ４ ) is a gas, The hydrocarbon gas that exhibits conformation during the aforementioned film formation is acetylene (C ２ H ２ ) gas or propylene (C ３ H ６ The method for forming a film according to claim 2, wherein the gas is...

5. The film formation method according to claim 1, wherein the plurality of hydrocarbon gases are alternately supplied into the processing chamber according to their respective types.

6. The film deposition method according to claim 1, wherein the temperature of the substrate is maintained at 200°C or below when the film deposition process is performed on the substrate.

7. The method for forming a film according to claim 6, wherein the pattern is formed on a mask film made of a chemically amplified resist.

8. The film formation method according to claim 1, wherein, after performing the aforementioned film formation process, an anisotropic etching process is performed on the substrate to remove carbon-containing residues.

9. The method for forming a film according to claim 1, wherein the noble gas is argon (Ar) gas.

10. A film deposition method comprising: housing a substrate having a pattern inside a processing chamber; supplying a film deposition gas to the processing chamber; and generating plasma from the film deposition gas using high-frequency power to perform a film deposition process on the substrate, A film-forming method wherein the film-forming gas comprises ethylene gas, a hydrocarbon gas of a different type than ethylene gas, and a noble gas.

11. The film formation method according to claim 10, wherein the hydrocarbon gas other than the ethylene gas is acetylene gas or propylene gas.

12. It is equipped with a processing chamber with a reduced internal pressure, A film deposition apparatus comprising: housing a substrate having a pattern inside the processing chamber; supplying a film deposition gas into the processing chamber; and generating plasma from the film deposition gas using high-frequency power to perform a film deposition process on the substrate, The aforementioned film-forming gas includes multiple types of hydrocarbon gases and noble gases. A film deposition apparatus in which, when the aforementioned multiple types of hydrocarbon gases are excited and converted into plasma, the composition of the active species generated from each of the hydrocarbon gases is different.

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