Substrate processing method, substrate processing apparatus, and substrate processing system

Abstract

This technology reduces the occurrence of defects in the root portion of the carbon film when forming a carbon film on the upper surface of a patterned undercoat. [Solution] A substrate processing method according to one aspect of the present disclosure comprises: preparing a substrate having a film to be etched and a base film formed on the film to be etched and having an upper surface and side surfaces; exposing the substrate to a plasma generated from a film-forming gas containing a raw material gas containing carbon and hydrogen to selectively form a first carbon film on the upper surface relative to the side surfaces of the base film; heat-treating the substrate to remove the hydrogen from the first carbon film; exposing the substrate to the plasma to form a second carbon film on the first carbon film; and etching the film to be etched using the base film, the first carbon film, and the second carbon film as masks.

Description

[Technical Field]

[0001] This disclosure relates to a substrate processing method, a substrate processing apparatus, and a substrate processing system. [Background technology]

[0002] Patent Document 1 discloses a technique for etching a substrate layer using a patterned carbon film as a mask, then forming an additional carbon film on top of the carbon film to increase its thickness, and further etching the substrate layer using the thickened carbon film as a mask. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Special Publication No. 2022-539699 [Overview of the project] [Problems that the invention aims to solve]

[0004] This disclosure provides a technique that can reduce the occurrence of defects in the root portion of a carbon film when forming a carbon film on the upper surface of a patterned substrate. [Means for solving the problem]

[0005] A substrate processing method according to one aspect of the present disclosure comprises: preparing a substrate having a film to be etched and a base film formed on the film to be etched, having an upper surface and side surfaces; exposing the substrate to a plasma generated from a film-forming gas containing a raw material gas containing carbon and hydrogen to selectively form a first carbon film on the upper surface relative to the side surfaces of the base film; heat-treating the substrate to desorb the hydrogen from the first carbon film; exposing the substrate to the plasma to form a second carbon film on the first carbon film; and etching the film to be etched using the base film, the first carbon film, and the second carbon film as masks. [Effects of the Invention]

[0006] According to this disclosure, it is possible to reduce the occurrence of defects in the root portion of the carbon film when forming a carbon film on the upper surface of a patterned substrate film. [Brief explanation of the drawing]

[0007] [Figure 1] This is a flowchart showing a substrate processing method according to the first example of the embodiment. [Figure 2] This is a cross-sectional view (1) showing a substrate processing method according to the first example of the embodiment. [Figure 3] This is a cross-sectional view (2) showing a substrate processing method according to the first example of the embodiment. [Figure 4] This is a cross-sectional view (3) showing a substrate processing method according to the first embodiment. [Figure 5] This is a cross-sectional view (4) showing a substrate processing method according to the first example of the embodiment. [Figure 6] This is a cross-sectional view (5) showing a substrate processing method according to the first embodiment. [Figure 7] This is a cross-sectional view (6) showing a substrate processing method according to the first embodiment. [Figure 8] Figure (1) shows a conventional substrate processing method. [Figure 9] Figure (2) shows a conventional substrate processing method. [Figure 10] Figure (3) shows a conventional substrate processing method. [Figure 11] Figure (4) shows a conventional substrate processing method. [Figure 12] Figure (5) shows a conventional substrate processing method. [Figure 13] Figure (6) shows a conventional substrate processing method. [Figure 14] This is a flowchart showing a substrate processing method according to a second embodiment. [Figure 15] This is a cross-sectional view (1) showing a substrate processing method according to a second embodiment. [Figure 16]It is a cross-sectional view (2) showing a substrate processing method according to the second example of the embodiment. [Figure 17] It is a cross-sectional view (3) showing a substrate processing method according to the second example of the embodiment. [Figure 18] It is a cross-sectional view (4) showing a substrate processing method according to the second example of the embodiment. [Figure 19] It is a cross-sectional view (5) showing a substrate processing method according to the second example of the embodiment. [Figure 20] It is a cross-sectional view (6) showing a substrate processing method according to the second example of the embodiment. [Figure 21] It is a cross-sectional view (7) showing a substrate processing method according to the second example of the embodiment. [Figure 22] It is a cross-sectional view (8) showing a substrate processing method according to the second example of the embodiment. [Figure 23] It is a cross-sectional view (9) showing a substrate processing method according to the second example of the embodiment. [Figure 24] It is a cross-sectional view (10) showing a substrate processing method according to the second example of the embodiment. [Figure 25] It is a cross-sectional view (11) showing a substrate processing method according to the second example of the embodiment. [Figure 26] It is a cross-sectional view (12) showing a substrate processing method according to the second example of the embodiment. [Figure 27] It is a diagram showing a substrate processing system according to the embodiment. [Figure 28] It is a schematic cross-sectional view showing a substrate processing apparatus according to the embodiment. [Figure 29] It is a diagram showing the result of observing the cross-section of a carbon film. [Figure 30] It is a diagram showing the result of measuring the composition of a carbon film. [Figure 31] It is a diagram showing the result of measuring the density of a carbon film.

Embodiments of the Invention

[0008] Hereinafter, exemplary embodiments of the present disclosure, not limited to those described herein, will be described with reference to the attached drawings. In all attached drawings, identical or corresponding members or components are denoted by the same or corresponding reference numerals, and redundant descriptions are omitted.

[0009] [Substrate processing method] (Example 1) A substrate processing method according to the first embodiment will be described with reference to Figures 1 to 7. Figure 1 is a flowchart of the substrate processing method according to the first embodiment. Figures 2 to 7 are cross-sectional views showing the substrate processing method according to the first embodiment. The substrate processing method according to the embodiment has steps S11 to S16 shown in Figure 1.

[0010] In step S11, the substrate 100 is prepared as shown in Figure 2. The substrate 100 has an etching target film 101 and an underlayment film 102. The etching target film 101 is, for example, a laminated film in which silicon nitride films and silicon oxide films are alternately stacked. The underlayment film 102 is formed on the etching target film 101. The underlayment film 102 is patterned. The underlayment film 102 has an upper surface 102a and a side surface 102b. The underlayment film 102 has through holes 102h. The side surface 102b forms the inner surface of the through holes 102h. The etching target film 101 has an exposed surface 101a. The exposed surface 101a is exposed from the underlayment film 102 through the through holes 102h. The underlayment film 102 is, for example, an amorphous carbon film.

[0011] In step S12, as shown in Figure 3, a carbon film 103 is selectively formed on the upper surface 102a of the substrate film 102 relative to the side surface 102b. The carbon film 103 has an upper surface 103a and a side surface 103b. For example, RF power is supplied to generate plasma from a deposition gas containing propylene gas, helium gas, and hydrogen gas, and the generated plasma is supplied to the substrate 100. In this case, a film deposition reaction occurs due to carbon-based deposition species in the plasma, and an etching reaction occurs due to hydrogen-active species in the plasma. Since carbon-based deposition species have a high adhesion coefficient, they tend to adhere to the upper surface 102a relative to the side surface 102b. Since hydrogen-active species have a low adhesion coefficient, they tend to reach and remain in the through-holes 102h. Therefore, film deposition reactions are more likely to occur on the upper surface 102a, and etching reactions are more likely to occur on the side surface 102b. As a result, a carbon film 103 can be selectively formed on the upper surface 102a relative to the side surface 102b of the substrate film 102. The thickness of the carbon film 103 is, for example, 100 nm to 200 nm. In this case, the time the carbon film 103 is exposed to the deposition gas is shortened, making it easier to prevent etching of the carbon film 103 by hydrogen-active species in the plasma generated from the deposition gas. Propylene gas is an example of a raw material gas containing carbon and hydrogen. The raw material gas may also be a hydrocarbon gas other than propylene gas, such as ethylene gas or acetylene gas. Helium gas is an example of an inert gas. The inert gas may also be a noble gas other than helium gas, such as argon gas, neon gas, or krypton gas. The inert gas may also be nitrogen gas. An example of the conditions for step S12 is as follows.

[0012] Conditions for Step S12 Propylene gas: 10 sccm to 50 sccm Helium gas: 300 sccm to 1000 sccm Hydrogen gas: 5 sccm to 50 sccm Pressure: 0.3 Torr to 2 Torr RF power: 300W or more and 1000W or less (40MHz or more) Substrate temperature (first temperature): 200℃ or more and 400℃ or less

[0013] In step S13, as shown in Figure 4, the substrate 100 is heat-treated to remove hydrogen from the carbon film 103. This increases the density of the carbon film 103 and improves its etching resistance to hydrogen-active species. The heat treatment of the substrate 100 may be carried out in an inert gas atmosphere. In this case, oxidation of the carbon film 103 can be prevented. Examples of inert gases include noble gases such as helium, argon, neon, and krypton, or nitrogen gas. The substrate temperature when removing hydrogen from the carbon film 103 may be higher than the substrate temperature when the carbon film 103 is formed. In this case, hydrogen is more easily removed from the carbon film 103. An example of the conditions for step S13 is as follows.

[0014] • Conditions for Step S13 Argon gas: 100 sccm to 5000 sccm Pressure: 0.1 Torr to 5 Torr Substrate temperature: 400℃ or higher and 800℃ or lower Time: 5 minutes or more and 60 minutes or less

[0015] In step S14, as shown in Figure 5, a carbon film 104 is selectively formed on the upper surface 103a of the carbon film 103 relative to the side surface 103b. The carbon film 104 can be formed, for example, in the same way as the carbon film 103. In step S14, the carbon film 103 is exposed to plasma generated from the deposition gas. Therefore, it is conceivable that the carbon film 103 may be etched by hydrogen-active species in the plasma. However, a carbon film 103 from which hydrogen has been removed has high etching resistance to hydrogen-active species, etc. Therefore, even when exposed to plasma generated from the deposition gas, etching reactions by hydrogen-active species in the plasma are unlikely to occur. As a result, a carbon film 104 can be selectively formed on the upper surface 103a of the carbon film 103 relative to the side surface 103b without etching the carbon film 103. The thickness of the carbon film 104 may be thicker than the thickness of the carbon film 103. The thickness of the carbon film 104 is, for example, 200 nm to 400 nm.

[0016] In step S15, as shown in Figure 6, the substrate 100 is heat-treated to remove hydrogen from the carbon film 104. This increases the density of the carbon film 104, improving its etching resistance to hydrogen-active species. The heat treatment conditions in step S15 may be the same as those in step S13. Step S15 may be omitted because the carbon film 104 is not exposed to the plasma (hydrogen-active species) of the film-forming gas after step S15. However, it is preferable to perform step S16 from the viewpoint of increasing etching resistance to the etching gas used in step S16, which will be described later.

[0017] In step S16, as shown in Figure 7, the film to be etched 101 is etched using the underlayer film 102, carbon film 103, and carbon film 104 as masks. This forms holes 101h in the film to be etched 101. For example, an etching gas capable of selectively etching the film to be etched 101 against the underlayer film 102, carbon film 103, and carbon film 104 is supplied to the substrate 100. This allows the film to be etched 101 to form holes 101h. For example, if the film to be etched 101 is a laminated film in which silicon nitride films and silicon oxide films are alternately stacked, the etching gas can be, for example, a gas containing fluorine and carbon (C x F y , C x F y H z (x, y, z can be integers greater than or equal to 1, etc.) Plasma may be generated from the etching gas.

[0018] As a result, holes 101h can be formed in the etchable film 101.

[0019] Next, we will explain conventional substrate processing methods with reference to Figures 8 to 13. Figures 8 to 13 are diagrams showing conventional substrate processing methods.

[0020] When a plasma is generated from a deposition gas containing a raw material gas containing carbon and hydrogen, and the generated plasma is supplied to a substrate 100 to form a carbon film 103, a film deposition reaction occurs due to carbon-based deposition species in the plasma, and an etching reaction occurs due to hydrogen-active species in the plasma. Carbon-based deposition species have a high adhesion coefficient, while hydrogen-active species have a low adhesion coefficient. Therefore, when forming a thick carbon film 103, the carbon film 103 formed in the initial stages of deposition is exposed to hydrogen-active species in the initial stages of deposition, as shown in Figure 8, and continues to be exposed to hydrogen-active species during deposition, as shown in Figure 9. In other words, when forming a thick carbon film 103, the carbon film 103 formed in the initial stages of deposition is exposed to hydrogen-active species for a long time. Therefore, the carbon film 103 formed in the initial stages of deposition is more easily etched. As a result, as shown in Figure 10, the base portion of the carbon film 103, which is the part formed in the initial stages of deposition, may become thinner. A thick film thickness is, for example, 300 nm to 1 μm.

[0021] When etching the target film 101 using the carbon film 103, which has a narrowed base, as a mask, the carbon film 103 tilts, as shown in Figure 11, resulting in poor straight-line etching of the target film 101. Also, as shown in Figure 12, the carbon film 103 tilts, causing the opening diameter of the holes 101h formed in the target film 101 to shrink or expand. Furthermore, as shown in Figure 13, the base of the carbon film 103 is brittle, causing it to crumble during etching and generate particles 103p.

[0022] According to the substrate processing method of the first embodiment, first, in step S12, a carbon film 103 is selectively formed on the upper surface 102a of the base film 102 against the side surface 102b. Next, in step S13, the substrate 100 is heat-treated to remove hydrogen from the carbon film 103. Next, in step S14, a carbon film 104 is selectively formed on the upper surface 103a of the carbon film 103 against the side surface 103b. Next, in step S15, the film to be etched 101 is etched using the base film, carbon film 103, and carbon film 104 as masks. Since the carbon film 103 from which hydrogen has been removed in step S13 has high etching resistance to hydrogen-active species, even when exposed to plasma generated from the film-forming gas in step S14, etching reactions by hydrogen-active species in the plasma are unlikely to occur. As a result, a carbon film 104 can be selectively formed on the upper surface 103a of the carbon film 103 against the side surface 103b without etching the carbon film 103. In other words, when forming carbon films (carbon films 103 and carbon films 104) on the upper surface of the patterned base film 102, it is possible to reduce the occurrence of defects in the root portion of the carbon films (carbon films 103 and carbon films 104).

[0023] (Example 2) Referring to Figures 14 to 26, a substrate processing method according to a second embodiment will be described. Figure 14 is a flowchart showing the substrate processing method according to a second embodiment. Figures 15 to 26 are cross-sectional views showing the substrate processing method according to a second embodiment.

[0024] The substrate processing method according to the second embodiment differs from the substrate processing method according to the first embodiment in that it involves forming a carbon film 104 and desorbing hydrogen from the carbon film 104, and then etching the film to be etched 101 after repeating this process a first time. In the following, the first number of repetitions is two or more. In the following, the case where the first number of repetitions is four will be used as an example. The substrate processing method according to the embodiment has steps S21 to S27 shown in Figure 14.

[0025] In step S21, prepare the substrate 100 as shown in Figure 15. Step S21 may be the same as step S11.

[0026] In step S22, as shown in Figure 16, a carbon film 103 is selectively formed on the upper surface 102a of the base film 102 relative to the side surface 102b. Step S22 may be the same as step S12.

[0027] In step S23, as shown in Figure 17, the substrate 100 is heat-treated to remove hydrogen from the carbon film 103. Step S23 may be the same as step S13.

[0028] In step S24, as shown in Figure 18, a carbon film 104-1 is selectively formed on the top surface 103a of the carbon film 103 relative to the side surface 103b. The carbon film 104-1 has a top surface 104-1a and a side surface 104-1b. The carbon film 104-1 can be formed, for example, in the same way as the carbon film 103. In step S24, the carbon film 103 is exposed to plasma generated from the deposition gas. Therefore, it is conceivable that the carbon film 103 may be etched by hydrogen-active species in the plasma. However, the carbon film 103 from which hydrogen has been removed has high etching resistance to hydrogen-active species, etc. Therefore, even when exposed to plasma generated from the deposition gas, etching reactions by hydrogen-active species in the plasma are unlikely to occur. As a result, the carbon film 104-1 can be selectively formed on the top surface 103a of the carbon film 103 relative to the side surface 103b without etching the carbon film 103. The thickness of carbon film 104-1 may be the same as the thickness of carbon film 103. The thickness of carbon film 104-1 is, for example, between 100 nm and 200 nm. In this case, the time that carbon film 104-1 is exposed to the deposition gas is shortened, making it easier to prevent etching of carbon film 104-1 by hydrogen-active species in the plasma generated from the deposition gas.

[0029] In step S25, as shown in Figure 19, the substrate 100 is heat-treated to remove hydrogen from the carbon film 104-1. This increases the density of the carbon film 104-1, improving its etching resistance to hydrogen-active species and the like. The heat treatment conditions in step S25 may be the same as those in step S23.

[0030] In step S26, it is determined whether the number of times steps S24 and S25 have been performed has reached the first number. In this example, the first number is 4. Steps S24 and S25 have been performed 1 time, and have not reached 4. Therefore, the process returns to step S24 and steps S24 and S25 are performed again.

[0031] In the second step S24, as shown in Figure 20, carbon film 104-2 is selectively formed on the upper surface 104-1a relative to the side surface 104-1b of carbon film 104-1. Carbon film 104-2 can be formed, for example, in the same way as carbon film 103. In the second step S24, carbon film 103 and carbon film 104-1 are exposed to plasma generated from the deposition gas. Therefore, it is conceivable that carbon film 103 and carbon film 104-1 may be etched by hydrogen-active species in the plasma. However, carbon film 103 and carbon film 104-1 from which hydrogen has been removed have high etching resistance to hydrogen-active species, etc. Therefore, even when exposed to plasma generated from the deposition gas, etching reactions by hydrogen-active species in the plasma are unlikely to occur. As a result, carbon film 104-2 can be selectively formed on the upper surface 104-1a relative to the side surface 104-1b of carbon film 104 without etching carbon film 103 and carbon film 104-1. The thickness of carbon film 104-2 may be the same as the thickness of carbon film 103. For example, the thickness of carbon film 104-2 is between 100 nm and 200 nm. In this case, the time that carbon film 104-2 is exposed to the deposition gas is shortened, making it easier to prevent etching of carbon film 104-2 by hydrogen-active species in the plasma generated from the deposition gas.

[0032] In the second step S25, as shown in Figure 21, the substrate 100 is heat-treated to remove hydrogen from the carbon film 104-2. This increases the density of the carbon film 104-2, improving its etching resistance to hydrogen-active species and the like. The heat treatment conditions in the second step S25 may be the same as those in step S23.

[0033] In the second step S26, it is determined whether the number of times steps S24 and S25 have been performed has reached the first count. In this example, the first count is 4. Steps S24 and S25 have been performed 2 times, which is not 4. Therefore, the process returns to step S24 and steps S24 and S25 are performed again.

[0034] In the third step S24, as shown in Figure 22, carbon film 104-3 is selectively formed on the upper surface 104-2a relative to the side surface 104-2b of carbon film 104-2. Carbon film 104-3 can be formed, for example, in the same way as carbon film 103. In the third step S24, carbon films 103, 104-1, and 104-2 are exposed to plasma generated from the deposition gas. Therefore, it is conceivable that carbon films 103, 104-1, and 104-2 may be etched by hydrogen-active species in the plasma. However, carbon films 103, 104-1, and 104-2 from which hydrogen has been removed have high etching resistance to hydrogen-active species, etc. Therefore, even when exposed to plasma generated from the deposition gas, etching reactions by hydrogen-active species in the plasma are unlikely to occur. As a result, carbon film 104-3 can be selectively formed on the upper surface 104-2a of carbon film 104 relative to the side surface 104-2b, without etching carbon film 103, carbon film 104-1, and carbon film 104-2. The thickness of carbon film 104-3 may be the same as the thickness of carbon film 103. The thickness of carbon film 104-3 is, for example, 100 nm to 200 nm. In this case, the time that carbon film 104-3 is exposed to the deposition gas is shortened, making it easier to prevent etching of carbon film 104-3 by hydrogen-active species in the plasma generated from the deposition gas.

[0035] In the third step S25, as shown in Figure 23, the substrate 100 is heat-treated to remove hydrogen from the carbon film 104-3. This increases the density of the carbon film 104-3, improving its etching resistance to hydrogen-active species and the like. The heat treatment conditions in the third step S25 may be the same as those in step S23.

[0036] In the third step S26, it is determined whether the number of times steps S24 and S25 have been performed has reached the first count. In this example, the first count is 4. Steps S24 and S25 have been performed 3 times, and have not reached 4. Therefore, the process returns to step S24 and steps S24 and S25 are performed again.

[0037] In the fourth step S24, as shown in Figure 24, carbon film 104-4 is selectively formed on the upper surface 104-3a relative to the side surface 104-3b of carbon film 104-3. Carbon film 104-4 can be formed, for example, in the same way as carbon film 103. In the fourth step S24, carbon films 103, 104-1, 104-2, and 104-3 are exposed to plasma generated from the deposition gas. Therefore, it is conceivable that carbon films 103, 104-1, 104-2, and 104-3 may be etched by hydrogen-active species in the plasma. However, carbon films 103, 104-1, 104-2, and 104-3 from which hydrogen has been removed have high etching resistance to hydrogen-active species, etc. Therefore, even when exposed to plasma generated from the deposition gas, etching reactions by hydrogen-active species in the plasma are unlikely to occur. As a result, carbon film 104-4 can be selectively formed on the upper surface 104-3a relative to the side surface 104-3b of carbon film 104 without etching carbon film 103, carbon film 104-1, carbon film 104-2, and carbon film 104-3. The thickness of carbon film 104-4 may be the same as the thickness of carbon film 103. The thickness of carbon film 104-4 is, for example, 100 nm to 200 nm. In this case, since the time that carbon film 104-4 is exposed to the deposition gas is shortened, etching of carbon film 104-4 by hydrogen-active species in the plasma generated from the deposition gas is easily prevented.

[0038] In the fourth step S25, as shown in FIG. 25, the substrate 100 is heat-treated to desorb hydrogen from the carbon film 104-4. As a result, the carbon film 104-4 becomes densified, and the etching resistance against hydrogen active species and the like is improved. The conditions of the heat treatment in the fourth step S25 may be the same as those of the heat treatment in step S23.

[0039] In the fourth step S26, it is determined whether or not the number of times steps S24 and S25 have been performed has reached the first number of times. In this example, the first number of times is 4. The number of times steps S24 and S25 have been performed is 4, and the number of times has reached 4. Therefore, the process proceeds to step S27.

[0040] In step S27, as shown in FIG. 26, the etching target film 101 is etched using the base film 102, the carbon film 103, the carbon films 104-1, 104-2, 104-3, and 104-4 as masks. As a result, holes 101h are formed in the etching target film 101. For example, an etching gas that can selectively etch the etching target film 101 with respect to the base film 102, the carbon film 103, the carbon films 104-1, 104-2, 104-3, and 104-4 is supplied to the substrate 100. As a result, the etching target film 101 can be etched to form holes 101h. For example, when the etching target film 101 is a laminated film in which a silicon nitride film and a silicon oxide film are alternately laminated, for example, a gas containing fluorine and carbon (C x F y 、C x F y H z : x, y, z are integers of 1 or more, etc.) can be used. Plasma may be generated from the etching gas.

[0041] As described above, holes 101h can be formed in the etching target film 101.

[0042] The substrate processing method according to the second embodiment provides the same effects as the substrate processing method according to the first embodiment. Specifically, it reduces the occurrence of defects in the root portion of the carbon film (carbon film 103 and carbon film 104) when forming the carbon film (carbon film 103 and carbon film 104) on the upper surface of the patterned undercoat 102.

[0043] [Substrate Processing System] Referring to Figure 27, a substrate processing system PS according to an embodiment will be described. Figure 27 is a diagram showing the substrate processing system PS according to an embodiment. In the following description, the case in which the substrate processing system PS has four processing chambers will be described, but the number of processing chambers is not limited to four. The number of load lock chambers and load ports is also not limited to the number shown in Figure 27.

[0044] The substrate processing system PS comprises processing units PM1 to PM4, vacuum transport chambers VTM, load lock chambers LLM1 to LLM3, atmospheric transport chamber LM, load ports LP1 to LP4, and control unit CT.

[0045] Processing units PM1 to PM4 are connected to the vacuum transfer chamber VTM via gate valves G11 to G14, respectively. The inside of processing units PM1 to PM4 is reduced to a predetermined vacuum atmosphere, and the substrate W is subjected to the desired processing inside. The substrate W is, for example, the substrate 100 mentioned above.

[0046] The processing apparatus PM1 performs, for example, a process to form a carbon film 103 on the substrate W (step S12 in Figure 1).

[0047] The processing device PM2 performs a process, for example, to remove hydrogen from the carbon film 103 (step S13 in Figure 1).

[0048] The processing device PM3 performs a process (step S14 in Figure 1) to selectively form a carbon film 104 on the upper surface 103a relative to the side surface 103b of the carbon film 103.

[0049] The processing device PM4 performs a process, for example, to remove hydrogen from the carbon film 104 (step S15 in Figure 1).

[0050] The vacuum transport chamber VTM is depressurized to a predetermined vacuum atmosphere. The vacuum transport chamber VTM is equipped with a transport mechanism TR1 capable of transporting substrates W under reduced pressure. The transport mechanism TR1 transports substrates W to the processing units PM1 to PM4 and the load lock chambers LLM1 to LLM3. The transport mechanism TR1 has, for example, two transport arms. However, it may have only one transport arm.

[0051] Load lock chambers LLM1 to LLM3 are connected to the vacuum transport chamber VTM via gate valves G21 to G23, and to the atmospheric transport chamber LM via gate valves G31 to G33. The atmosphere inside load lock chambers LLM1 to LLM3 can be switched between atmospheric and vacuum.

[0052] The atmospheric transport chamber LM is an atmospheric environment, and for example, a downflow of clean air is formed. An aligner (not shown) for aligning the substrate W is provided in the atmospheric transport chamber LM. A transport mechanism TR2 is provided in the atmospheric transport chamber LM. The transport mechanism TR2 has, for example, one transport arm. There may be two or more transport arms. The transport mechanism TR2 transports the substrate W to the load lock chambers LLM1 to LLM3, the carriers C in the load ports LP1 to LP4, and the aligner.

[0053] Load ports LP1 to LP4 are located on the long side walls of the atmospheric transport chamber LM. Load ports LP1 to LP4 are fitted with carriers C containing substrates W or empty carriers C via gate valves G41 to G44. Carrier C is, for example, a FOUP (Front Opening Unified Pod).

[0054] The control unit CT controls various parts of the substrate processing system PS. For example, the control unit CT operates the processing units PM1 to PM4, the transport mechanisms TR1 and TR2, opens and closes the gate valves G11 to G14, G21 to G23, G31 to G33, and G41 to G44, and switches the atmosphere inside the load lock chambers LLM1 to LLM3.

[0055] The substrate processing system PS comprises a plurality of processing chambers (processing devices PM1 to PM4), a vacuum transport chamber (vacuum transport chamber VTM) for vacuum transporting the substrate W between the plurality of processing chambers, and a control device CT. The control device CT controls each process performed by processing devices PM1 to PM4. This allows the substrate W to be processed in each processing chamber without being exposed to the atmosphere, that is, without breaking the vacuum.

[0056] The etching process for the film to be etched 101 (step S16 in Figure 1) may be performed in at least one of the processing devices PM1 to PM4, and may be performed in a device different from the substrate processing system PS.

[0057] Furthermore, two or more of the following processes may be performed in the same apparatus: forming the carbon film 103, removing hydrogen from the carbon film 103, forming the carbon film 104, and removing hydrogen from the carbon film 104. Alternatively, all of the following processes may be performed in the same apparatus: forming the carbon film 103, removing hydrogen from the carbon film 103, forming the carbon film 104, and removing hydrogen from the carbon film 104.

[0058] Furthermore, regarding steps S22, S23, S24, S25, and S27 in Figure 14, all processes may be performed by different processing units, or two or more processes may be performed by the same processing unit.

[0059] [Substrate Processing Equipment] Referring to Figure 28, a substrate processing apparatus 1 applicable as processing apparatus PM1 in the substrate processing system PS will be described. Processing apparatuses PM2, PM3, and PM4 may have the same configuration as processing apparatus PM1. Figure 28 is a schematic cross-sectional view showing a substrate processing apparatus 1 according to an embodiment.

[0060] The substrate processing apparatus 1 comprises a substantially cylindrical, airtight processing container 2. An exhaust chamber 21 is provided in the central part of the bottom wall of the processing container 2.

[0061] The exhaust chamber 21 has a shape that protrudes downward, for example, a substantially cylindrical shape. An exhaust passage 22 is connected to the exhaust chamber 21, for example, on the side of the exhaust chamber 21.

[0062] An exhaust section 24 is connected to the exhaust passage 22 via a pressure adjustment section 23. The pressure adjustment section 23 includes, for example, a pressure adjustment valve such as a butterfly valve. The exhaust section 24 includes, for example, a vacuum pump. The exhaust passage 22 is configured so that the inside of the processing container 2 can be depressurized by the exhaust section 24. A transport port 25 is provided on the side of the processing container 2. The transport port 25 is configured to be openable and closable by a gate valve 26. The loading and unloading of substrates W between the processing container 2 and a transport chamber (not shown) is performed through the transport port 25.

[0063] A mounting table 3 is provided inside the processing container 2 for holding the substrate W in a substantially horizontal position. The mounting table 3 is formed in a substantially circular shape when viewed from above. The mounting table 3 is supported by a support member 31. A substantially circular recess 32 is formed on the upper surface 3a of the mounting table 3 for mounting a substrate W with, for example, a diameter of 300 mm. The recess 32 has an inner diameter that is slightly larger than the diameter of the substrate W (for example, about 1 mm to 4 mm). The depth of the recess 32 is set to be substantially the same as the thickness of the substrate W. The mounting table 3 is formed from a ceramic material such as aluminum nitride (AlN). The mounting table 3 may also be formed from a metallic material such as nickel (Ni). Instead of the recess 32, a guide ring may be provided on the periphery of the upper surface 3a of the mounting table 3 to guide the substrate W.

[0064] A lower electrode 33, for example, is embedded in the mounting base 3. A temperature control mechanism 34 is embedded below the lower electrode 33. The temperature control mechanism 34 adjusts the mounting base 3 or the substrate W placed on it to a set temperature based on a control signal from the control unit 9. If the entire mounting base 3 is made of metal, the entire mounting base 3 functions as the lower electrode, so the lower electrode 33 does not need to be embedded in the mounting base 3. The mounting base 3 is provided with a plurality (for example, three) of lifting pins 41 for holding and raising and lowering the substrate W placed on the mounting base 3. The material of the lifting pins 41 may be, for example, ceramics such as alumina (Al2O3) or quartz. The lower ends of the lifting pins 41 are attached to a support plate 42. The support plate 42 is connected to a lifting mechanism 44 provided outside the processing container 2 via a lifting shaft 43.

[0065] The lifting mechanism 44 is installed, for example, at the bottom of the exhaust chamber 21. The bellows 45 is provided between the opening 21a for the lifting shaft 43 formed on the lower surface of the exhaust chamber 21 and the lifting mechanism 44. The shape of the support plate 42 may be such that it can move up and down without interfering with the support member 31 of the mounting base 3. The lifting pin 41 is configured to move up and down between the upper side of the upper surface 3a of the mounting base 3 and the lower side of the upper surface 3a of the mounting base 3 by the lifting mechanism 44. In other words, the lifting pin 41 is configured to protrude from the upper surface 3a of the mounting base 3.

[0066] A gas supply unit 5 is provided on the top wall 27 of the processing container 2 via an insulating member 28. The gas supply unit 5 forms the upper electrode and faces the lower electrode 33. An RF power supply 51 is connected to the gas supply unit 5 via a matching unit 52. The frequency band of the RF power supply 51 is, for example, 450 kHz to 2.45 GHz. By supplying RF power from the RF power supply 51 to the gas supply unit 5, an RF electric field is generated between the gas supply unit 5 and the lower electrode 33. The gas supply unit 5 includes a hollow gas diffusion chamber 53. On the lower surface of the gas diffusion chamber 53, numerous holes 54 are evenly arranged, for example, for distributing and supplying processing gas into the processing container 2. A heating mechanism 55 is embedded above the gas diffusion chamber 53 in the gas supply unit 5. The heating mechanism 55 is heated to a set temperature by being powered from a power supply unit (not shown) based on a control signal from the control unit 9.

[0067] A gas supply passage 6 is provided in the gas diffusion chamber 53. The gas supply passage 6 is in communication with the gas diffusion chamber 53. A gas source 61 is connected to the upstream side of the gas supply passage 6 via a gas line 62. The gas source 61 includes, for example, a supply source for various processing gases, a mass flow controller, and valves (none of which are shown). The processing gas includes the gas used in the substrate processing method according to the first and second examples of the embodiments described above. The processing gas is introduced from the gas source 61 to the gas diffusion chamber 53 via the gas line 62.

[0068] The control unit 9 is an electronic circuit such as a CPU (Central Processing Unit), FPGA (Field Programmable Gate Array), or ASIC (Application Specific Integrated Circuit). The control unit 9 performs the various control operations described in this specification by executing instruction codes stored in memory or by circuit design for special applications.

[0069] [Operation of the circuit board processing unit] The operation when step S12 of the substrate processing method according to the embodiment is performed in the substrate processing apparatus 1 will be described.

[0070] First, the control unit 9 opens the gate valve 26 and uses a transport mechanism (not shown) to transport the substrate W into the processing container 2 and place it on the mounting table 3. The substrate W may be the substrate 100 prepared in step S11 described above. After the control unit 9 retracts the transport mechanism from the processing container 2, it closes the gate valve 26.

[0071] Next, the control unit 9 controls each part of the substrate processing apparatus 1 to perform the aforementioned step S12 on the substrate W placed on the mounting table 3 inside the processing container 2.

[0072] Next, the control unit 9 removes the substrate W from the processing container 2 in the reverse order of loading the substrate W into the processing container 2. Thus, step S12 is performed for one substrate W.

[0073] [Experimental results] (Experiment A) In Experiment A, samples A1 to A4, as shown below, were prepared, and the cross-sections of each sample A1 to A4 were observed.

[0074] <Sample A1> First, a substrate was prepared having a film to be etched and an underlayment film formed on the film to be etched, having an upper surface and side surfaces. The underlayment film was a silicon oxide film. Next, by performing step S12 described above, a carbon film with a thickness of 100 nm was selectively formed on the upper surface relative to the side surfaces of the silicon oxide film. Next, by performing step S13 described above, the carbon film was heat-treated. Next, by performing step S14 described above, a carbon film with a thickness of 300 nm was selectively formed on the upper surface relative to the side surfaces of the carbon film. The conditions for step S12, step S13, and step S14 are as follows.

[0075] • Conditions for step S12 and step S14 Propylene gas: 11 sccm Helium gas: 330 sccm Hydrogen gas: 11 sccm Pressure: 0.5 Torr RF power: 300W (40MHz or more) Substrate temperature (1st temperature): 400℃

[0076] • Conditions for Step S13 Argon gas: 1800 sccm Pressure: 2 Torr Substrate temperature: 550℃ Duration: 60 minutes

[0077] <Sample A2> First, the same substrate as sample A1 was prepared. Next, steps S12, S13, and S14 described above were performed. For sample A2, the time in step S13 was changed from 60 minutes to 30 minutes compared to sample A1. The conditions for step S12, step S14, and step S13, other than the time, were the same as for sample A1.

[0078] <Sample A3> First, the same substrate as sample A1 was prepared. Next, steps S12, S13, and S14 described above were performed. For sample A3, the time in step S13 was changed from 60 minutes to 10 minutes compared to sample A1. The conditions for step S12, step S14, and step S13, other than the time, were the same as for sample A1.

[0079] <Sample A4> First, the same substrate as sample A1 was prepared. Next, steps S12 and S14 described above were performed. For sample A2, step S13 was not performed compared to sample A1. The conditions for step S12 and step S14 were the same as for sample A1.

[0080] Figure 29 shows the results of observing the cross-section of the carbon film. The cross-section of each sample was observed using a scanning electron microscope (SEM). Figure 29 schematically shows the SEM image of the cross-section of each sample.

[0081] As shown in Figure 29, no defects were found at the base of the carbon film in samples A1 to A3, whereas in sample A4, the base of the carbon film was narrowed and a defect occurred. This result indicates that by heat-treating the carbon film during its formation to remove hydrogen, it is possible to reduce the occurrence of defects at the base of the carbon film when forming the carbon film on the upper surface of the patterned undercoat.

[0082] (Experiment B) In Experiment B, samples B1 to B3, as shown below, were prepared, and the film composition and film density of each sample B1 to B3 were measured.

[0083] <Sample B1> First, a substrate having a flat underlayer on its surface was prepared. The underlayer was a silicon oxide film. Next, by performing step S12 described above, a carbon film with a thickness of 100 nm was formed on the upper surface of the silicon oxide film. Next, by performing step S13 described above, the carbon film was heat-treated. The conditions for step S12 and step S13 are as follows.

[0084] Conditions for Step S12 Propylene gas: 11 sccm Helium gas: 330 sccm Hydrogen gas: 11 sccm Pressure: 0.5 Torr RF power: 300W (40MHz or more) Substrate temperature (1st temperature): 400℃

[0085] • Conditions for Step S13 Argon gas: 1800 sccm Pressure: 2 Torr Substrate temperature: 550℃ Duration: 60 minutes

[0086] <Sample B2> First, the same substrate as sample B1 was prepared. Next, steps S12 and S13 described above were performed. For sample B2, the time in step S13 was changed from 60 minutes to 30 minutes compared to sample B1. The conditions for step S12 and the conditions for step S13 other than the time were the same as for sample B1.

[0087] <Sample B3> First, the same substrate as sample B1 was prepared. Next, step S12 described above was performed. For sample B2, step S13 was not performed compared to sample B1. The conditions for step S12 were the same as for sample B1.

[0088] Figure 30 shows the results of measuring the composition of the carbon films. The composition of the carbon films of each sample was measured by Rutherford Back-Scattering Spectroscopy (RBS) and Hydrogen Forward-Scattering Spectroscopy (HFS). In Figure 30, the carbon (C) composition and hydrogen (H) composition of each sample are shown as relative values ​​[%] with the carbon and hydrogen compositions of sample B3 set to 100%, respectively.

[0089] As shown in Figure 30, samples B1 and B2 have a higher carbon composition and a lower hydrogen composition compared to sample B3. This result indicates that hydrogen is removed from the carbon film by heat treatment.

[0090] Figure 31 shows the results of measuring the density of carbon films. The density of the carbon film for each sample was calculated based on the composition and film thickness measured by Rutherford backscattering analysis and hydrogen forward scattering analysis. In Figure 31, the film density of each sample is shown as a relative value [%] with the film density of sample B3 set to 100%.

[0091] As shown in Figure 31, the carbon film density is higher in samples B1 and B2 compared to sample B3. This result indicates that heat treatment of the carbon film increases its density.

[0092] In the above embodiment, carbon film 103 is an example of a first carbon film, and carbon film 104, carbon film 104-1, carbon film 104-2, carbon film 104-3, and carbon film 104-4 are examples of second carbon films.

[0093] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The above embodiments may be omitted, replaced, or modified in various ways without departing from the scope and spirit of the appended claims.

[0094] In the above embodiment, a case was described in which the substrate processing apparatus 1 has one mounting stage 3 in the processing container 2, but the disclosure is not limited thereto. For example, the substrate processing apparatus 1 may have two independently temperature-controllable mounting stages 3 in the processing container 2. In this case, a process of forming a carbon film 103 (step S12 in Figure 1) and a process of forming a carbon film 104 (step S14 in Figure 1) may be performed by placing the substrate W on one of the mounting stages 3. Alternatively, a process of desorbing hydrogen from the carbon film (steps S13 and S15 in Figure 1) may be performed by placing the substrate W on the other mounting stage 3. Furthermore, for example, the substrate processing apparatus 1 may have three or more independently temperature-controllable mounting stages 3 in the processing container 2. [Explanation of symbols]

[0095] 100 circuit boards 101 Etching target film 102 Undercoat 103 Carbon film 104, 104-1, 104-2, 104-3, 104-4 carbon film

Claims

1. The process involves preparing a substrate having a film to be etched and an underlayer film formed on the film to be etched, which has an upper surface and side surfaces. The substrate is exposed to a plasma generated from a film-forming gas containing a raw material gas containing carbon and hydrogen, thereby selectively forming a first carbon film on the upper surface relative to the side surface of the underlayer film. The substrate is heat-treated to remove the hydrogen from the first carbon film, The substrate is exposed to the plasma to form a second carbon film on the first carbon film, Etching the film to be etched using the aforementioned undercoat, the first carbon film, and the second carbon film as masks, A substrate processing method having the following characteristics.

2. The process involves heat-treating the substrate before etching the film to be etched, thereby removing the hydrogen from the second carbon film. The substrate processing method according to claim 1.

3. The thickness of the second carbon film is greater than the thickness of the first carbon film. The substrate processing method according to claim 1.

4. The process includes repeatedly forming the second carbon film and removing the hydrogen from the second carbon film in this order multiple times. The substrate processing method according to claim 2.

5. The thickness of the second carbon film is the same as the thickness of the first carbon film. The substrate processing method according to claim 4.

6. The temperature at which the hydrogen is removed from the first carbon film is higher than the temperature at which the first carbon film is formed. The substrate processing method according to claim 1.

7. The removal of hydrogen from the first carbon film is carried out in an inert gas atmosphere. The substrate processing method according to claim 1.

8. The aforementioned inert gas is argon gas. The substrate processing method according to claim 7.

9. The aforementioned raw material gas is a hydrocarbon gas. A substrate processing method according to any one of claims 1 to 8.

10. The aforementioned underlayer film is an amorphous carbon film. A substrate processing method according to any one of claims 1 to 8.

11. The formation of the first carbon film and the desorption of hydrogen from the first carbon film are carried out in the same processing vessel. A substrate processing method according to any one of claims 1 to 8.

12. A substrate processing apparatus for etching a film to be etched formed on a substrate, The substrate has an etching target film and an underlayer film formed on the etching target film, having an upper surface and side surfaces. The substrate processing apparatus is The substrate is exposed to a plasma generated from a film-forming gas containing a raw material gas containing carbon and hydrogen, thereby selectively forming a first carbon film on the upper surface relative to the side surface of the underlayer film. The substrate is heat-treated to remove the hydrogen from the first carbon film, The substrate is exposed to the plasma to form a second carbon film on the first carbon film, Etching the film to be etched using the aforementioned undercoat, the first carbon film, and the second carbon film as masks, A control unit configured to perform the following: Circuit board processing equipment.

13. A substrate processing system for etching a film to be etched formed on a substrate, The substrate has an etching target film and an underlayer film formed on the etching target film, having an upper surface and side surfaces. The substrate processing system is A first apparatus that exposes the substrate to a plasma generated from a film-forming gas containing a raw material gas containing carbon and hydrogen, thereby selectively forming a first carbon film on the upper surface of the underlayer with respect to the side surface, A second apparatus for heat-treating the substrate and removing the hydrogen from the first carbon film, A third apparatus for exposing the substrate to the plasma and forming a second carbon film on the first carbon film, A fourth apparatus for etching the film to be etched using the aforementioned undercoat, the first carbon film, and the second carbon film as masks, Equipped with, PCB processing system.

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