Embedding method and film forming device

Abstract

An embedding method according to one aspect of the present disclosure comprises the steps of: (a) preparing a substrate having, on the surface thereof, a recess including a bottom surface formed by a first film and a side surface formed by a second film of a material different from the first film; (b) forming a silicon-containing film on the bottom surface and the side surface of the recess; (c) exposing the substrate to plasma generated from an etching gas containing a halogen-containing gas and selectively etching the silicon-containing film relative to the second film; and (d) repeating steps (b) and (c). Step (b) includes repeating the steps of: supplying a nitrogen-containing gas to the substrate and forming more adsorption sites on the surface of the first film than on the surface of the second film; supplying a silicon-containing gas to the substrate and allowing the silicon-containing gas to be adsorbed onto the adsorption sites; and exposing the substrate to hydrogen plasma, in this order.

Description

Embedding method and film forming apparatus

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

[0002] Techniques have been disclosed for filling recesses with a film by repeating film formation and etching (see, for example, Patent Documents 1 to 3).

[0003] JP 2024-504165 A JP 2023-145565 A JP 2020-518134 A

[0004] The present disclosure provides a technique that can fill a recess with a silicon-containing film from the bottom surface thereof.

[0005] A filling method according to one aspect of the present disclosure includes: (a) preparing a substrate having a recess on a surface thereof, the recess including a bottom surface formed by a first film and side surfaces formed by a second film made of a material different from the first film; (b) forming a silicon-containing film on the bottom surface and the side surfaces of the recess; (c) exposing the substrate to plasma generated from an etching gas including a halogen-containing gas to selectively etch the silicon-containing film relative to the second film; and (d) repeating steps (b) and (c), wherein step (b) includes repeating the following steps in this order: supplying a nitrogen-containing gas to the substrate to form more adsorption sites on the surface of the first film than on the surface of the second film; supplying a silicon-containing gas to the substrate to adsorb the silicon-containing gas onto the adsorption sites; and exposing the substrate to hydrogen plasma.

[0006] According to the present disclosure, the silicon-containing film can be embedded into the bottom surface of the recess.

[0007] 1 is a flowchart showing a filling method according to an embodiment; FIG. 2 is a cross-sectional view (1) showing the filling method according to an embodiment; FIG. 3 is a cross-sectional view (2) showing the filling method according to an embodiment; FIG. 4 is a cross-sectional view (4) showing the filling method according to an embodiment; FIG. 5 is a cross-sectional view (5) showing the filling method according to an embodiment; FIG. 6 is a cross-sectional view (6) showing the filling method according to an embodiment. A flowchart showing an example of a film formation process; FIG. 7 is a view showing a surface reaction of a silicon film in a film formation process; FIG. 8 is a view showing a surface reaction of a silicon oxide film in a film formation process; A cross-sectional view showing a substrate according to a modified example; A cross-sectional view showing a film formation apparatus according to an embodiment; A view showing the relationship between the first number of times and the thickness of a SiCN film; FIG. 1 is a view showing the results of measuring the etching amount of each film; FIG. 2 is a view showing the results of measuring the etching amount of each film.

[0008] Hereinafter, non-limiting exemplary embodiments of the present disclosure will be described with reference to the accompanying drawings. In all the accompanying drawings, the same or corresponding reference numerals are used to designate the same or corresponding members or components, and redundant descriptions will be omitted.

[0009] [Filling Method] A filling method according to an embodiment will be described with reference to Figs. 1 to 10. Fig. 1 is a flowchart showing the filling method according to an embodiment. Figs. 2 to 7 are cross-sectional views showing the filling method according to an embodiment. Fig. 8 is a flowchart showing an example of the film forming step S2. Fig. 9 is a diagram showing a surface reaction of the silicon film 110 in the film forming step S2. Fig. 10 is a diagram showing a surface reaction of the silicon oxide film 120 in the film forming step S2.

[0010] As shown in FIG. 1, the filling method according to the embodiment includes a preparation step S1, a film forming step S2, an etching step S3, and a determination step S4.

[0011] The preparation step S1 includes preparing a substrate 100, as shown in FIG. 2 . The substrate 100 has a silicon film 110 and a silicon oxide film 120. The silicon film 110 has a flat upper surface. The silicon oxide film 120 is provided on the upper surface of the silicon film 110. The silicon oxide film 120 has a convex shape. The silicon film 110 and the silicon oxide film 120 form a recess 130. The recess 130 has a bottom surface 131, side surfaces 132, and an upper surface 133. The silicon film 110 forms the bottom surface 131. The silicon oxide film 120 forms the side surfaces 132 and the upper surface 133. The silicon film 110 is an example of a first film, and the silicon oxide film 120 is an example of a second film. The recess 130 is, for example, a trench. The recess 130 may also be a hole.

[0012] The film forming step S2 is performed after the preparation step S1. As shown in FIG. 3 , the film forming step S2 includes forming a SiCN film 140 thicker on the bottom surface 131 of the recess 130 than on the side surface 132 and the top surface 133. The SiCN film 140 is an example of a silicon-containing film. For example, the film forming step S2 includes steps S21 to S27 shown in FIG. 8 .

[0013] In step S21, as shown in FIG. 9A and FIG. 10A, ammonia (NH ３ ) on the surface of the silicon film 110 than on the surface of the silicon oxide film 120. ｘ Ammonia is an example of a nitrogen-containing gas.

[0014] Step S22 is performed after step S21. Step S22 includes purging the space in which the substrate 100 is accommodated of ammonia.

[0015] Step S23 is performed after step S22. In step S23, 1,1,3,3-tetrachloro-1,3-disilacyclobutane is supplied to the substrate 100. 1,1,3,3-tetrachloro-1,3-disilacyclobutane has an adsorption site (—NH ｘ). For this reason, 1,1,3,3-tetrachloro-1,3-disilacyclobutane is adsorbed to the surface of the silicon film 110 (see FIG. 9B) more than to the surface of the silicon oxide film 120 (see FIG. 10B). This is because the number of adsorption sites on the surface of the silicon film 110 is greater than the number of adsorption sites on the surface of the silicon oxide film 120. 1,1,3,3-tetrachloro-1,3-disilacyclobutane is an example of a silicon-containing gas. 1,1,3,3-tetrachloro-1,3-disilacyclobutane is represented by the following structural formula:

[0016]

[0017] Step S24 is performed after step S23 and includes purging the space in which the substrate 100 is accommodated of 1,1,3,3-tetrachloro-1,3-disilacyclobutane.

[0018] Step S25 is performed after step S24. Step S25 includes exposing the substrate 100 to a plasma generated from hydrogen (hereinafter referred to as "hydrogen plasma"). The hydrogen plasma generates hydrogen ions (H ＋ ) When the substrate 100 is exposed to hydrogen plasma, hydrogen ions contained in the hydrogen plasma act on the adsorption sites on the surfaces of the silicon film 110 and the silicon oxide film 120 where 1,1,3,3-tetrachloro-1,3-disilacyclobutane is adsorbed. As a result, a portion of the 1,1,3,3-tetrachloro-1,3-disilacyclobutane is desorbed from the surfaces of the silicon film 110 and the silicon oxide film 120. At this time, more 1,1,3,3-tetrachloro-1,3-disilacyclobutane is adsorbed on the surface of the silicon film 110 than on the surface of the silicon oxide film 120. Therefore, as shown in FIG. 9C, a portion of the 1,1,3,3-tetrachloro-1,3-disilacyclobutane remains on the surface of the silicon film 110. In contrast, as shown in FIG. 10C, 1,1,3,3-tetrachloro-1,3-disilacyclobutane is completely or almost completely desorbed from the surface of the silicon oxide film 120.

[0019] Step S26 is performed after step S25. Step S26 includes purging the space in which the substrate 100 is housed of residual hydrogen.

[0020] Step S27 is performed after step S26. In step S27, it is determined whether steps S21 to S26 have been performed a first number of times. If the number of times has not reached the first number (NO in step S27), steps S21 to S26 are performed again. If the number of times has reached the first number of times (YES in step S27), the process ends. In this manner, steps S21 to S26 are repeated in this order until the number of times has reached the first number of times. As a result, as shown in FIG. 3 , a SiCN film 140 is formed that is thicker on the bottom surface 131 of the recess 130 than on the side surface 132 and top surface 133. The first number of times is, for example, two or more times.

[0021] The etching step S3 is performed after the film forming step S2. As shown in FIG. 4, the etching step S3 includes removing the SiCN film 140 formed on the side surface 132 and the top surface 133 while leaving the SiCN film 140 formed on the bottom surface 131. The etching step S3 is performed, for example, in the same processing chamber as the film forming step S2. For example, in the etching step S3, fluoromethane (CH ３ F) and oxygen (O ２ The substrate 100 is exposed to plasma generated from a mixed gas of fluoromethane and oxygen. The plasma generated from the mixed gas of fluoromethane and oxygen has the property of selectively etching the SiCN film 140 relative to the silicon oxide film 120. Therefore, when the substrate 100 is exposed to the plasma generated from the mixed gas of fluoromethane and oxygen, the SiCN film 140 formed on the side surface 132 and the top surface 133 is selectively removed without etching the silicon oxide film 120, as shown in FIG. 4 . This exposes at least a portion of the silicon oxide film 120 on the side surface 132. At this time, the SiCN film 140 formed on the bottom surface 131 is thicker than the side surface 132 and the top surface 133. Therefore, the SiCN film 140 on the bottom surface 131 remains. The mixed gas of fluoromethane and oxygen is an example of an etching gas. Fluoromethane is an example of a halogen-containing gas.

[0022] The determination step S4 is performed after the etching step S3. In the determination step S4, it is determined whether the film forming step S2 and the etching step S3 have been performed a second number of times. If the number of times has not reached the second number of times (NO in the determination step S4), the film forming step S2 and the etching step S3 are performed again. If the number of times has reached the second number of times (YES in the determination step S4), the process ends. The second number of times is, for example, two or more times.

[0023] 5, in the second film forming step S2, the SiCN film 140 is formed thicker on the bottom surface 131 of the recess 130 than on the side surface 132 and the top surface 133. As a result, the SiCN film 140 fills in the recess 130 from the bottom surface 131.

[0024] 6, in the second etching step S3, the silicon oxide film 120 is not etched, and the SiCN film 140 formed on the side surface 132 and the top surface 133 is selectively removed. At this time, since the SiCN film 140 formed on the bottom surface 131 is thicker than the side surface 132 and the top surface 133, the SiCN film 140 on the bottom surface 131 remains.

[0025] In this manner, the film forming step S2 and the etching step S3 are repeated in this order until the number of times of implementation reaches the second number. As a result, as shown in FIG. 7 , the SiCN film 140 can be embedded in the recess 130 from the bottom surface 131. That is, the SiCN film 140 can be embedded in the recess 130 by bottom-up film formation. As a result, the SiCN film 140 can be embedded in the recess 130 without generating voids or seams.

[0026] In contrast, when the SiCN film 140 is embedded not only on the bottom surface 131 of the recess 130 but also on the side surfaces 132 of the recess 130, voids and seams are likely to occur between the SiCN films 140 embedded on the two opposing side surfaces 132.

[0027] Referring to FIG. 11 , a substrate 200 according to a modified example that can be used in the embedding method according to the embodiment will be described. FIG. 11 is a cross-sectional view showing the substrate 200 according to the modified example. The substrate 200 has a silicon film 210 and a silicon oxide film 220. The silicon film 210 has a base portion 211 and a protrusion portion 212. A plurality of protrusion portions 212 are provided on the base portion 211. The silicon oxide film 220 is provided on the side and upper surfaces of the protrusion portion 212. The silicon oxide film 220 covers the side and upper surfaces of the protrusion portion 221 without covering the upper surface of the base portion 211. The silicon film 210 and the silicon oxide film 220 form a recess 230. The recess 230 has a bottom surface 231, a side surface 232, and an upper surface 233. The silicon film 210 forms the bottom surface 231. The silicon oxide film 220 forms the side surface 232 and the upper surface 233. The silicon film 210 is an example of a first film, and the silicon oxide film 220 is an example of a second film. By using the filling method according to the embodiment on such a substrate 200, a silicon-containing film (e.g., a SiCN film) can be filled into the recess 230 without generating voids or seams.

[0028] [Film Forming Apparatus] The film forming apparatus 1 according to the embodiment will be described with reference to Fig. 12. Fig. 12 is a cross-sectional view showing the film forming apparatus 1 according to the embodiment.

[0029] The film forming apparatus 1 includes a processing chamber 2. The processing chamber 2 has a substantially cylindrical shape. The processing chamber 2 is a vacuum chamber capable of reducing the pressure inside. An exhaust chamber 21 is provided in the center of the bottom wall of the processing chamber 2.

[0030] The exhaust chamber 21 has a generally cylindrical shape that protrudes downward. An exhaust flow path 22 is connected to the side of the exhaust chamber 21. An exhaust unit 24 is connected to the exhaust flow path 22 via a pressure adjustment unit 23. The pressure adjustment unit 23 includes a pressure adjustment valve such as a butterfly valve. The pressure adjustment unit 23 adjusts the pressure inside the processing vessel 2. The exhaust unit 24 includes a vacuum pump. The exhaust unit 24 reduces the pressure inside the processing vessel 2 via the exhaust flow path 22. A transfer port 25 is provided on the side of the processing vessel 2. The transfer port 25 is an opening through which the substrate W passes when being loaded into the processing vessel 2 and when being unloaded from the processing vessel 2. The transfer port 25 is opened and closed by a gate valve 26.

[0031] A mounting table 3 is provided within the processing chamber 2. The mounting table 3 holds the substrate W in a substantially horizontal position. The mounting table 3 has a substantially circular shape in a plan view. The mounting table 3 is supported by a support member 31. A recess 32 is provided in the surface of the mounting table 3. The recess 32 has a substantially circular shape in a plan view. The substrate W is mounted in the recess 32. The recess 32 has an inner diameter slightly larger than the diameter of the substrate W. The recess 32 has a depth substantially equal to the thickness of the substrate W. The mounting table 3 is made of a ceramic material such as aluminum nitride (AlN). The mounting table 3 may also be made of a metal material such as nickel (Ni). Instead of the recess 32, an annular guide member that guides the peripheral edge of the substrate W may be provided on the surface of the mounting table 3.

[0032] A lower electrode 33 is provided inside the mounting table 3. An RF power supply 34 is connected to the lower electrode 33 via a matching box 35. The RF power supply 34 supplies a first RF (Radio Frequency) power to the lower electrode 33. The first RF power is bias RF power for attracting ions into the substrate W. The first RF power has a frequency in the range of 100 kHz to 60 MHz, for example. A DC (Direct Current) power supply may be connected to the lower electrode 33. The DC power supply supplies bias DC power or pulsed DC power to the lower electrode 33. The lower electrode 33 may be grounded. When the entire mounting table 3 is made of metal, the entire mounting table 3 functions as the lower electrode. Therefore, the lower electrode 33 does not need to be provided inside the mounting table 3.

[0033] A temperature adjustment mechanism 36 is provided inside the mounting table 3. The temperature adjustment mechanism 36 is located below the lower electrode 33. The temperature adjustment mechanism 36 adjusts the temperature of the substrate W placed in the recess 32 to a set temperature based on a control signal from the controller 9. The temperature adjustment mechanism 36 includes, for example, a heater. The temperature adjustment mechanism 36 may also include a fluid flow path through which a temperature adjustment fluid flows.

[0034] The mounting table 3 is provided with a plurality of (for example, three) lift pins 41. The lift pins 41 hold and lift up and down the substrate W placed in the recess 32. Each lift pin 41 is made of, for example, alumina (Al ２ O ３ The lift pins 41 are made of ceramics such as quartz. The lift pins 41 may be made of quartz. The lower ends of the lift pins 41 are attached to a support plate 42. The support plate 42 is connected to a lift mechanism 44 provided outside the processing vessel 2 via a lift shaft 43.

[0035] The lifting mechanism 44 is provided below the exhaust chamber 21. A bellows 45 is provided between the lifting mechanism 44 and an opening 21a for the lifting shaft 43 formed in the lower surface of the exhaust chamber 21. The support plate 42 has a shape that allows it to rise and fall without coming into contact with the support member 31 of the mounting table 3. The lifting mechanism 44 raises and lowers the upper ends of the lifting pins 41 between a position above the bottom surface of the recess 32 and a position below the bottom surface of the recess 32. This causes the substrate W to rise and lower between a position where it is placed on the bottom surface of the recess 32 (the position shown in FIG. 12 ) and a position away from the bottom surface of the recess 32 (not shown).

[0036] The lower end of the support member 31 passes through the opening 21b of the exhaust chamber 21. The lower end of the support member 31 is supported by a lifting mechanism 46 via a lifting plate 47 provided below the processing vessel 2. A bellows 48 is provided between the bottom of the exhaust chamber 21 and the lifting plate 47. This allows the airtightness inside the processing vessel 2 to be maintained even when the lifting plate 47 moves up and down.

[0037] The lifting mechanism 46 lifts and lowers the lifting plate 47 to lift and lower the mounting table 3. This allows the gap between the mounting table 3 and the gas supply unit 5 to be adjusted.

[0038] A gas supply unit 5 is provided on a ceiling wall 27 of the processing vessel 2 via an insulating member 28. The gas supply unit 5 functions as an upper electrode. The gas supply unit 5 faces the lower electrode 33. An RF power supply 51 is connected to the gas supply unit 5 via a matching unit 52. The RF power supply 51 supplies second RF power to the gas supply unit 5. The second RF power is RF power for generating plasma required for film formation and etching of the substrate W. The second RF power has a frequency in the range of 10 MHz to 1000 MHz, for example. When RF power is supplied from the RF power supply 51 to the gas supply unit 5, an RF electric field is generated between the gas supply unit 5 (upper electrode) and the lower electrode 33.

[0039] The gas supply unit 5 has a gas diffusion chamber 53. The gas diffusion chamber 53 has a hollow shape. A number of holes 54 are arranged, for example, evenly, on the bottom surface of the gas diffusion chamber 53 to distribute and supply the processing gas into the processing vessel 2. A heating mechanism 55 is embedded above the gas diffusion chamber 53 in the gas supply unit 5. The heating mechanism 55 includes, for example, a heater. The heating mechanism 55 heats the gas supply unit 5 to a set temperature based on a control signal from the control unit 9.

[0040] A gas supply line 6 communicates with the gas diffusion chamber 53. A gas source 61 is connected to the upstream side of the gas supply line 6 via a gas line 62. The gas source 61 includes a supply source for various process gases, a mass flow controller, and a valve. The various process gases include the process gases used in the embedding method according to the embodiment. The various process gases are introduced from the gas source 61 into the gas diffusion chamber 53 via the gas line 62.

[0041] The film forming apparatus 1 includes a control unit 9. 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 executes various control operations described in this specification by executing instruction codes stored in a memory or by being a circuit designed for a specific application.

[0042] [Experimental Results] (First Experiment) The following describes the results of an experiment that confirmed that by repeating steps S21 to S26 a first number of times in the film formation process S2, a thicker SiCN film 140 can be formed on the bottom surface 131 of the recess 130 than on the side surface 132 and top surface 133.

[0043] First, a substrate having a silicon film on its surface and a substrate having a silicon oxide film on its surface were prepared. Subsequently, steps S21 to S27 were performed on each substrate to form a SiCN film on the silicon film and the silicon oxide film. In the film-forming process S2, the SiCN film was formed under a plurality of conditions with different first counts in step S27, and the thickness of each SiCN film was measured to determine the first count at which the SiCN film formation on the silicon film and the silicon oxide film started.

[0044] Fig. 13 is a diagram showing the relationship between the first number of times and the thickness of the SiCN film. In Fig. 13, the horizontal axis represents the first number of times, and the vertical axis represents the thickness of the SiCN film. In Fig. 13, the circles and solid line represent the results for substrates having a silicon film on their surfaces, and the triangles and dashed line represent the results for substrates having a silicon oxide film on their surfaces. The circles and triangles represent measured values, and the solid and dashed lines are approximate straight lines.

[0045] As shown in FIG. 13 , when a SiCN film is formed on a silicon film, the thickness of the SiCN film increases in proportion to the first number of repetitions immediately after the start of the SiCN film formation. In contrast, when a SiCN film is formed on a silicon oxide film, the thickness of the SiCN film increases in proportion to the first number of repetitions after a predetermined number of repetitions have elapsed since the start of the SiCN film formation. In other words, the incubation time when forming a SiCN film on a silicon film is shorter than the incubation time when forming a SiCN film on a silicon oxide film. From the results of FIG. 13 , it can be said that by repeating steps S21 to S26 a first number of times in the film formation process S2, a thicker SiCN film 140 can be formed on the bottom surface 131 formed by the silicon film 110 than on the side surface 132 and top surface 133 formed by the silicon oxide film 120.

[0046] (Second Experiment) The results of an experiment that confirmed that the SiCN film 140 can be selectively etched relative to the silicon oxide film 120 by exposing it to plasma generated from a mixed gas of fluoromethane and oxygen in the etching step S3 will be described.

[0047] First, a substrate having a silicon nitride (SiN) film on its surface, a substrate having a SiCN film on its surface, a substrate having a silicon carbide (SiC) film on its surface, and a silicon oxide (SiO ２ Substrates having a fluoromethane (fluoroisotope) film on their surface were prepared. Each substrate was then exposed to plasma generated from a mixed gas of fluoromethane and oxygen. The thickness of each film was measured before and after exposure to the plasma, and the etching amount, which is the thickness of each film etched by exposure to the plasma, was calculated.

[0048] 14 is a diagram showing the results of measuring the etching amount of each film. In FIG. 14, the etching amount of the SiN film, the etching amount of the SiCN film, and the etching amount of the SiC film are shown relative to the etching amount of the SiO ２ The etching amount is expressed as a relative value when the etching amount of the film is set to 1.

[0049] 14, it can be seen that the etching amount of the SiN film is 34.1, the etching amount of the SiCN film is 25.1, and the etching amount of the SiC film is 13.7. From the results in FIG. 14, it can be seen that in the etching step S3, by exposing the film to plasma generated from a mixed gas of fluoromethane and oxygen, the SiO ２ It can be said that the SiN film, the SiCN film, and the SiC film can be selectively etched relative to the film.

[0050] (Third Experiment) The results of an experiment that confirmed that the SiCN film 140 can be selectively etched relative to the silicon oxide film 120 when a mixed gas of fluoromethane and hydrogen is used instead of the mixed gas of fluoromethane and oxygen in the second experiment will be described.

[0051] First, a substrate having a SiN film on its surface, a substrate having a SiCN film on its surface, a substrate having a SiC film on its surface, and a SiO ２ Substrates with films on their surfaces were prepared. Each substrate was then exposed to plasma generated from a mixture of fluoromethane and hydrogen gas. The thickness of each film was measured before and after exposure to the plasma, and the etching amount, which is the thickness of each film etched by exposure to the plasma, was calculated.

[0052] 15 is a diagram showing the results of measuring the etching amount of each film. In FIG. 15, the etching amount of the SiN film, the etching amount of the SiCN film, and the etching amount of the SiC film are shown relative to the etching amount of the SiO ２ The etching amount is expressed as a relative value when the etching amount of the film is set to 1.

[0053] 15, it can be seen that the etching amount of the SiN film is 12.0, the etching amount of the SiCN film is 6.5, and the etching amount of the SiC film is 0.7. From the results in FIG. 15, it can be seen that in the etching step S3, by exposing the film to plasma generated from a mixed gas of fluoromethane and hydrogen, the SiO ２ It can be said that the SiN film and the SiCN film can be selectively etched relative to the film.

[0054] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive, and the above-described embodiments may be omitted, substituted, or modified in various ways without departing from the scope and spirit of the appended claims.

[0055] In the above embodiment, the case where the silicon-containing gas is 1,1,3,3-tetrachloro-1,3-disilacyclobutane has been described, but the present disclosure is not limited thereto. The silicon-containing gas is used to adsorb the silicon-containing gas onto the adsorption site (—NH ｘ The silicon-containing gas may be a gas containing silicon, carbon, and a halogen. The halogen may be fluorine (F), chlorine (Cl), bromine (Br), iodine (I), or a combination thereof.

[0056] In the above embodiment, the nitrogen-containing gas is ammonia, but the present disclosure is not limited to this. The nitrogen-containing gas provides more adsorption sites (-NH ｘ The nitrogen-containing gas may be a gas that forms a nitrogen-containing gas such as ammonia, diazene (N ２ H ２ ), hydrazine (N ２ H ４ ), organic hydrazines (e.g., monomethylhydrazine (CH ３ (NH)NH ２ )), nitrogen (N２ ) and hydrogen (H ２ ) or a mixture of these gases.

[0057] In the above embodiment, the etching gas is a mixed gas of fluoromethane and oxygen, but the present disclosure is not limited to this. The etching gas may be any gas that has the property of selectively etching a SiCN film relative to a silicon oxide film. The etching gas may be a fluorocarbon (C ｘ F ｙ ) and oxygen. The fluorocarbon may be, for example, CF ４ , C ３ F ６ , C ３ F ８ , C ４ F ８ , C ４ F ６ or a combination thereof. The etching gas is a hydrofluorocarbon (C ｘ H ｙ F ｚ The hydrofluorocarbon may be, for example, a mixed gas of CHF ３ , C.H. ２ F ２ , C.H. ３ The etching gas may be a mixture of a gas containing fluorine (F) and oxygen. The fluorine-containing gas may be, for example, fluorine (F ２ ), hydrogen fluoride (HF), nitrogen trifluoride (NF ３ ), chlorine trifluoride (ClF ３ ) or a combination thereof. The etching gas may be a mixed gas of a gas containing chlorine (Cl) and oxygen, or a mixed gas of a gas containing bromine (Br) and oxygen. The etching gas may contain sulfur (S). The etching gas may be a mixed gas of hydrogen (H ２ The etching gas may contain nitrogen (N ２ ), and may contain an inert gas such as argon (Ar).

[0058] In the above embodiment, the silicon-containing film is a SiCN film, but the present disclosure is not limited to this. The silicon-containing gas may be a silicon nitride film or a silicon carbide film.

[0059] In the above embodiment, the first film is a silicon film and the second film is a silicon oxide film, but the present disclosure is not limited to this. The first film and the second film may be films formed of different materials.

[0060] In the above embodiment, the film forming apparatus is a single-wafer type apparatus that processes substrates one by one, but the present disclosure is not limited to this. For example, the film forming apparatus may be a batch type apparatus that processes multiple substrates at once.

[0061] REFERENCE SIGNS LIST 100 Substrate 110 Silicon film 120 Silicon oxide film 130 Recess 131 Bottom surface 132 Side surface 133 Top surface 140 SiCN film S1 Preparation step S2 Film formation step S3 Etching step S4 Determination step

Claims

1. A filling method comprising the steps of: (a) preparing a substrate having a recess on its surface, the recess having a bottom surface formed by a first film and side surfaces formed by a second film made of a material different from the first film; (b) forming a silicon-containing film on the bottom surface and side surfaces of the recess; (c) exposing the substrate to plasma generated from an etching gas including a halogen-containing gas to selectively etch the silicon-containing film relative to the second film; and (d) repeating steps (b) and (c), wherein step (b) includes repeating the steps of supplying a nitrogen-containing gas to the substrate to form more adsorption sites on the surface of the first film than on the surface of the second film; supplying a silicon-containing gas to the substrate to adsorb the silicon-containing gas onto the adsorption sites; and exposing the substrate to hydrogen plasma, in this order.

2. The method of claim 1, wherein the exposing to hydrogen plasma includes desorbing a portion of the silicon-containing gas adsorbed on the adsorption sites.

3. The embedding method according to claim 1, wherein step (c) includes exposing at least a portion of the second film on the side surface.

4. The embedding method according to claim 1, wherein the step (c) is carried out in the same processing vessel as the step (b).

5. The filling method according to any one of claims 1 to 4, wherein the first film is a silicon film, the second film is a silicon oxide film, and the silicon-containing film is a SiCN film.

6. The embedding method according to claim 5, wherein the silicon-containing gas is 1,1,3,3-tetrachloro-1,3-disilacyclobutane, the nitrogen-containing gas is ammonia, and the halogen-containing gas is fluoromethane.

7. The embedding method according to claim 6, wherein the etching gas further contains hydrogen or oxygen.

8. A film formation apparatus comprising: a processing vessel that accommodates a substrate; a gas supply unit that supplies a gas into the processing vessel; and a control unit, wherein the control unit is configured to execute the following steps: (a) preparing a substrate having a recess on a surface thereof, the recess including a bottom surface formed by a first film and side surfaces formed by a second film made of a material different from the first film; (b) forming a silicon-containing film on the bottom surface and the side surfaces of the recess; (c) exposing the substrate to plasma generated from an etching gas that includes a halogen-containing gas, to selectively etch the silicon-containing film relative to the second film; and (d) repeating steps (b) and (c), wherein step (b) includes repeating the steps of supplying a nitrogen-containing gas to the substrate to form more adsorption sites on the surface of the first film than on the surface of the second film; supplying a silicon-containing gas to the substrate to cause the silicon-containing gas to adsorb to the adsorption sites; and exposing the substrate to hydrogen plasma, in this order.

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