Film formation method and film formation apparatus

Abstract

The present invention provides a film forming method and a film forming apparatus capable of selectively forming a semiconductor film on a nitride film among a nitride film and an oxide film. The film forming method includes the following steps: supplying a fluorine-containing gas to a substrate in which a region exposing the nitride film and a region exposing the oxide film are adjacent, forming fluorine on the substrate, and selectively etching the nitride film among the nitride film and the oxide film to make the surface of the nitride film recess with respect to the surface of the oxide film to form a stepped surface on the side surface of the oxide film; and after the step of adsorbing fluorine on the substrate and forming the stepped surface, supplying a source gas containing a semiconductor material to the substrate to selectively form a semiconductor film on the nitride film among the nitride film and the oxide film.

Description

Technical Field

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

[0002] The film forming method described in Patent Document 1 includes the following steps: supplying a chlorine-containing gas to a substrate and adsorbing the chlorine-containing gas; and forming a silicon nitride film on the substrate on which the chlorine-containing gas has been adsorbed. The substrate has a silicon nitride film and a silicon oxide film. The chlorine-containing gas prevents the formation of the silicon nitride film with respect to the silicon oxide film. Therefore, a new silicon nitride film can be selectively formed on the old silicon nitride film.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2017-174919 Summary of the Invention

[0006] Problems to be Solved by the Invention

[0007] One aspect of the present disclosure provides a technique capable of selectively forming a semiconductor film on a nitride film among a nitride film and an oxide film.

[0008] Solutions for Solving the Problems

[0009] The film forming method according to one aspect of the present disclosure includes the following steps:

[0010] Supplying a fluorine-containing gas to a substrate in which a region exposing a nitride film and a region exposing an oxide film are adjacent, adsorbing fluorine to the substrate, and selectively etching the nitride film among the nitride film and the oxide film so that the surface of the nitride film is recessed with respect to the surface of the oxide film to form a stepped surface on the side surface of the oxide film; and

[0011] After the step of adsorbing fluorine to the substrate and forming the stepped surface, supplying a source gas containing a semiconductor material to the substrate to selectively form a semiconductor film on the nitride film among the nitride film and the oxide film.

[0012] Effects of the Invention

[0013] According to one aspect of the present disclosure, a semiconductor film can be selectively formed on a nitride film among a nitride film and an oxide film. Brief Description of the Drawings

[0014] Figure 1 is a flowchart showing a film forming method according to one embodiment.

[0015] Figure 2A It is a side view of a substrate prepared by S1 through Figure 1 .

[0016] Figure 2B It is a side view of a substrate obtained by S2 through Figure 1 .

[0017] Figure 2C It is a side view of a substrate obtained by S3 through Figure 1 .

[0018] Figure 2D It is a side view of a substrate obtained by S4 through Figure 1 .

[0019] Figure 2E It is a side view of a substrate obtained by S5 through Figure 1 .

[0020] Figure 2F It is a side view of a substrate obtained by the second S4.

[0021] Figure 2G It is a side view of a substrate obtained by the second S5.

[0022] Figure 3A It is a diagram showing an example of the relationship between the film thickness of a semiconductor film and the film formation time of the semiconductor film.

[0023] Figure 3B It is a diagram showing an example of the change in Δt before and after supplying a fluorine-containing gas.

[0024] Figure 4A It is a diagram showing an example of the change in substrate temperature over time.

[0025] Figure 4B It is a diagram showing another example of the change in substrate temperature over time.

[0026] Figure 5 It is a cross-sectional view showing an example of a film formation apparatus for implementing the Figure 1 film formation method.

[0027] Explanation of Reference Numerals

[0028] 10: Substrate; 11: Nitride film; 12: Native oxide film; 13: Oxide film; 20: Fluorine; 30: Semiconductor film; 40: Semiconductor material; A1: First region; A2: Second region; 100: Film formation apparatus; 110: Processing container; 120: Substrate holding part; 130: Heating part; 140: Gas supply part; 150: Gas discharge part; 160: Control part. Detailed implementation mode

[0029] Next, embodiments of the present disclosure will be described with reference to the accompanying drawings. In addition, in each drawing, the same or corresponding structures are denoted by the same or corresponding reference numerals, and the description may sometimes be omitted.

[0030] First, with reference to Figure 1 , Figure 2A , Figure 2B , Figure 2C , Figure 2D , Figure 2E , Figure 2F and Figure 2G a film forming method will be described. The film forming method includes, for example, preparing the substrate 10 (S1), removing the natural oxide film 12 (S2), performing fluorine adsorption and step formation (S3), forming the semiconductor film 30 (S4), removing the unnecessary semiconductor material 40 (S5), and these steps are executed in the described order.

[0031] In Figure 1 of S1, the substrate 10 is prepared as shown in Figure 2A . The preparation of the substrate 10 includes, for example, disposing the substrate 10 inside the processing container 110 described later. The substrate 10 has a first region A1 and a second region A2 adjacent to the first region A1 on the main surface.

[0032] The first region A1 is a region where the natural oxide film 12 covering the nitride film 11 is exposed. The nitride film 11 is usually naturally oxidized in the atmosphere and is thus covered with the natural oxide film 12. The material of the nitride film 11 is not particularly limited, and for example, it is silicon nitride.

[0033] The second region A2 is a region where the oxide film 13 is exposed. The material of the oxide film 13 is not particularly limited, and for example, it is silicon oxide.

[0034] The number of the first regions A1 is one in [[ID=3 , but may also be multiple. For example, two first regions A1 can be arranged to sandwich the second region A2. Similarly, the number of the second regions A2 is one in ​ , but may also be multiple. For example, two second regions A2 can be arranged to sandwich the first region A1.

[0035] In addition, in ​ only the first region A1 and the second region A2 exist, but a third region may also exist. The third region is a region where a film of a material different from that of the first region A1 and the second region A2 is exposed.

[0036] In addition to the nitride film 11 and the oxide film 13, the substrate 10 further has a base substrate 14. The base substrate 14 is, for example, a semiconductor substrate such as a silicon wafer. In addition, the base substrate 14 can also be a glass substrate or the like. The nitride film 11 and the oxide film 13 are formed on the surface of the base substrate 14.

[0037] In addition, the substrate 10 can also have a base film between the base substrate 14 and the oxide film 13, and the base film is formed of a material different from that of the base substrate 14 and the oxide film 13. Similarly, the substrate 10 can also have a base film between the base substrate 14 and the nitride film 11, and the base film is formed of a material different from that of the base substrate 14 and the nitride film 11.

[0038] In ​ S2 of, as ​ shown, the native oxide film 12 is removed. This is to expose the nitride film 11 in the first region A1 by removing the native oxide film 12.

[0039] When the nitride film 11 is silicon nitride, the native oxide film 12 contains silicon. In this case, for example, the native oxide film 12 is removed by a process called Chemical Oxide Removal (COR).

[0040] COR supplies HF gas and NH3 gas to the substrate 10, makes these gases react with the native oxide film 12 to generate ammonium hexafluorosilicate ((NH4)2SiF6), and sublimes this product by heating. By this sublimation, the native oxide film 12 is removed, so that the nitride film 11 is exposed in the first region A1.

[0041] After the native oxide film 12 is removed, the nitride film 11 and the oxide film 13 are exposed to HF gas and NH3 gas. These gases remove oxides, so they etch not only the native oxide film 12 but also the oxide film 13.

[0042] If the oxide film 13 in the nitride film 11 and the oxide film 13 is selectively etched after the native oxide film 12 is removed, the surface of the oxide film 13 will be recessed relative to the surface of the nitride film 11, ​ and the processing time of S3 of

[0043] Therefore, COR is carried out under the condition that the nitride film 11 can be continuously etched after the native oxide film 12 is removed. It is preferable to carry out COR under the condition that the etching rates of the oxide film 13 and the nitride film 11 are the same. An example of the processing conditions of COR is as follows.

[0044] Substrate temperature: 60 °C

[0045] Flow rate of HF gas: 300 sccm (standard cc / min)

[0046] Flow rate of NH3 gas: 300 sccm

[0047] Flow rate of N2 gas: 1500 sccm

[0048] Internal air pressure of the processing container: 27 Pa

[0049] Processing time: 1.6 min

[0050] In addition, the N2 gas is a dilution gas. As a substitute for the N2 gas, noble gases such as Ar gas can be used as the dilution gas.

[0051] In addition, in this embodiment, the substrate 10 having the natural oxide film 12 is prepared, but the substrate 10 without the natural oxide film 12 can also be prepared. In this case, of course, the removal of the natural oxide film 12 (S2) is not required.

[0052] In ​ of S3, as ​ shown, the fluorine-containing gas is supplied to the substrate 10 exposing the nitride film 11, so that the fluorine 20 is adsorbed on the substrate 10, and the nitride film 11 in the nitride film 11 and the oxide film 13 is selectively etched, and the surface of the nitride film 11 is recessed with respect to the surface of the oxide film 13 to form the stepped surface 15 on the side surface of the oxide film 13.

[0053] As described above, by adsorbing the fluorine 20 on the substrate 10 in S3 of ​ , it becomes easy to selectively form the semiconductor film 30 on the nitride film 11 in the nitride film 11 and the oxide film 13 in S4 of ​ . The reason will be described with reference to ​ and ​ .

[0054] As ​ shown, in the fixed time Δt from the start of supplying the source gas of the semiconductor film 30, the semiconductor film 30 hardly grows, and the film thickness of the semiconductor film 30 hardly increases. After passing through the fixed time Δt, the nucleus of the semiconductor film 30 is formed, and starting from this nucleus, the growth begins, and the film thickness of the semiconductor film 30 begins to increase. The time Δt is called the incubation time.

[0055] As ​ shown, Δt is determined by the material of the substrate of the semiconductor film 30. The Δt in the case where the substrate is the nitride film 11 is shorter than the Δt in the case where the substrate is the oxide film 13. By supplying the fluorine-containing gas, this difference becomes obvious.

[0056] By supplying a fluorine-containing gas, fluorine 20 is adsorbed onto the substrate 10. As a result, Δt becomes slightly longer when the substrate is the nitride film 11, whereas Δt becomes significantly longer when the substrate is the oxide film 13.

[0057] It can be estimated that the degree of elongation varies depending on the substrate material because, as ​ shown, fluorine 20 is more likely to be adsorbed onto the oxide film 13 than the nitride film 11 among the nitride film 11 and the oxide film 13. However, fluorine 20 can also be adsorbed onto the nitride film 11.

[0058] After supplying the fluorine-containing gas, Δt is shorter when the substrate is the nitride film 11 than when the substrate is the oxide film 13. Moreover, this time difference is sufficiently long. Therefore, the semiconductor film 30 can be selectively formed on the nitride film 11 using this time difference.

[0059] The supply time of the source gas for the semiconductor film 30 is set to be longer than Δt when the substrate is the nitride film 11 and shorter than Δt when the substrate is the oxide film 13. Thus, the semiconductor film 30 hardly forms on the oxide film 13.

[0060] In addition, as described above, in ​ S3, the surface of the nitride film 11 is recessed with respect to the surface of the oxide film 13 to form the stepped surface 15 on the side surface of the oxide film 13. Therefore, in ​ S4, the lateral protrusion of the semiconductor film 30 from the surface of the nitride film 11 can be suppressed.

[0061] The height H of the stepped surface 15 can be smaller than the target film thickness of the semiconductor film 30, but can also be equal to or greater than the target film thickness of the semiconductor film 30. In the latter case, the lateral protrusion of the semiconductor film 30 from the surface of the nitride film 11 can be reliably suppressed. The height H of the stepped surface 15 is, for example, 2 nm or more.

[0062] Furthermore, in the case where the formation of the semiconductor film 30 (S4) and the removal of the unnecessary semiconductor material 40 (S5) are repeated as ​ shown, the target film thickness of the semiconductor film 30 refers to the total target film thickness of the multiple semiconductor films 30.

[0063] The fluorine-containing gas is, for example, F2 gas. The F2 gas adsorbs fluorine 20 onto the substrate 10 and selectively etches the nitride film 11 to recess the surface of the nitride film 11. The processing conditions of ​ S3 using the F2 gas are as follows, for example.

[0064] Substrate temperature: 250 °C to 300 °C

[0065] Flow rate of F2 gas: 100 sccm to 10,000 sccm

[0066] Internal air pressure of the processing container: 13 Pa to 20,000 Pa

[0067] Processing time: 0.1 min to 30 min.

[0068] In addition, as described above, COR is originally a treatment for removing oxides, but if the conditions are changed, it is also possible to selectively etch the nitride film 11 in the nitride film 11 and the oxide film 13. Therefore, the fluorine-containing gas can also be HF gas. The HF gas is used together with the NH3 gas. An example of the processing conditions for COR that selectively etches the nitride film 11 is as follows.

[0069] Substrate temperature: 60 °C

[0070] Flow rate of HF gas: 100 sccm

[0071] Flow rate of NH3 gas: 300 sccm

[0072] Flow rate of N2 gas: 3000 sccm

[0073] Internal air pressure of the processing container: 26 Pa

[0074] Processing time: 1 min to 30 min.

[0075] The HF gas adsorbs fluorine 20 onto the substrate 10 in the same manner as the F2 gas, and selectively etches the nitride film 11 in cooperation with the NH3 gas, causing the surface of the nitride film 11 to be recessed to form the stepped surface 15. After the fluorine adsorption and step formation (S3), the semiconductor film 30 is formed (S4).

[0076] In ​ S4 of ​ As shown, a raw material gas containing a semiconductor material is supplied to the substrate 10, and the semiconductor film 30 is selectively formed on the nitride film 11 in the nitride film 11 and the oxide film 13. The semiconductor film 30 is formed, for example, by CVD (Chemical Vapor Deposition) method.

[0077] The raw material gas of the semiconductor film 30 contains at least one of silicon (Si) and germanium (Ge), for example. In this case, the semiconductor film 30 contains at least one of silicon (Si) and germanium (Ge).

[0078] The semiconductor film 30 is, for example, an amorphous silicon film. The raw material gas of the amorphous silicon film is a silane-based gas such as silane (SiH4) gas or disilane (Si2H6) gas.

[0079] The film formation conditions of the amorphous silicon film are determined according to the type of source gas. When the source gas is Si2H6 gas, the film formation conditions are as follows, for example.

[0080] Substrate temperature: 350 °C to 450 °C

[0081] Flow rate of Si2H6 gas: 100 sccm to 10,000 sccm

[0082] Internal pressure of the processing chamber: 27 Pa to 1333 Pa

[0083] Processing time: 5 min to 300 min.

[0084] In addition, the semiconductor film 30 can also be a polycrystalline silicon film. The source gas of the polycrystalline silicon film is the same as that of the amorphous silicon film. Additionally, the semiconductor film 30 can be a germanium (Ge) film or a silicon-germanium (SiGe) film.

[0085] The source gas of the Ge film is, for example, a germane-based gas such as germane (GeH4) gas or digermane (Ge2H6) gas. Additionally, the source gas of the SiGe film is, for example, a silane-based gas and a germanium-based gas.

[0086] The semiconductor film 30 can contain dopants or not. Dopants are, for example, carbon (C), phosphorus (P), or boron (B), etc.

[0087] According to this embodiment, since fluorine adsorption and step formation (S3) are performed as described above before forming the semiconductor film 30 (S4), the semiconductor film 30 can be selectively formed on the surface of the nitride film 11.

[0088] However, as ​ shown, granular semiconductor materials 40 sometimes deposit on the surface of the oxide film 13. The semiconductor material 40 is the same material as the semiconductor film 30 and contains, for example, at least one of Si and Ge.

[0089] The deposition of the semiconductor material 40 occurs when the semiconductor film 30 has a thick target film thickness, the continuous supply time of the source gas is long, and the difference between the continuous supply time and Δt is small. Additionally, the deposition of the semiconductor material 40 also occurs due to insufficient adsorption of fluorine 20.

[0090] In ​ S5, as ​ shown, a halogen-containing gas is supplied to the substrate 10 to remove the granular semiconductor material 40 deposited on the surface of the oxide film 13. The unnecessary semiconductor material 40 generated during the formation of the semiconductor film 30 (S4) can be removed.

[0091] The halogen-containing gas etches starting from the surface of the semiconductor material 40, and thus the semiconductor is etched at a rate of volume reduction corresponding to the specific surface area (surface area per unit volume). The larger the specific surface area, the faster the rate of volume reduction.

[0092] The semiconductor material 40 is granular. Therefore, the specific surface area of the semiconductor material 40 is larger than that of the semiconductor film 30. Thus, the semiconductor material 40 can be etched with little etching of the semiconductor film 30.

[0093] The halogen-containing gas contains a halogen. Specifically, it contains at least one selected from fluorine (F), chlorine (Cl), and bromine (Br). Among them, fluorine etches not only the semiconductor material 40 but also the nitride film 11 and the oxide film 13.

[0094] Therefore, in order not to etch the nitride film 11 and the oxide film 13, the halogen-containing gas may not contain fluorine. The halogen-containing gas that does not contain fluorine is, for example, Cl2 gas, HCl gas, Br2 gas, or HBr gas.

[0095] The supply conditions of the halogen-containing gas are determined according to the type of the halogen-containing gas. The supply conditions of Cl2 gas are as follows, for example.

[0096] Substrate temperature: 350 °C to 450 °C

[0097] Flow rate of Cl2 gas: 100 sccm to 5000 sccm

[0098] Internal pressure of the processing container: 27 Pa to 667 Pa

[0099] Processing time: 0.5 min to 30 min.

[0100] According to the present embodiment, the halogen-containing gas is supplied to the substrate 10 as described above to remove the granular semiconductor material 40 deposited on the surface of the oxide film 13. The nuclei that are the starting points of the growth of the semiconductor material 40 can be removed, and Δt can be initialized.

[0101] As ​ shown, setting the formation of the semiconductor film 30 (S4) and the removal of the semiconductor material 40 (S5) as one cycle, the initialization of Δt is effective when this cycle is repeatedly implemented. In S4 after the second time, the granular deposition of the semiconductor material 40 on the surface of the oxide film 13 can be suppressed.

[0102] In ​ S6, it is checked whether the number of cycles has reached the target number. The target number is predetermined through experiments or the like such that when the number of cycles reaches the target number, the film thickness of the semiconductor film 30 reaches the target film thickness. The thicker the target film thickness, the larger the target number.

[0103] When the number of cycles is less than the target number of cycles (in ​ S6 is "No"), the film thickness of the semiconductor film 30 has not reached the target film thickness. Therefore, the formation of the semiconductor film 30 (S4) and the removal of the semiconductor material 40 (S5) are performed again. In ​ the substrate 10 obtained by the second S4 is shown, and in ​ the substrate 10 obtained by the second S5 is shown.

[0104] If the formation of the semiconductor film 30 (S4) is performed in multiple times, the size of the granular semiconductor material 40 deposited each time can be reduced. The smaller the size of the semiconductor material 40, the larger the specific surface area of the semiconductor material 40, and the shorter the time required for the removal of the semiconductor material 40 (S5). Thus, etching of the semiconductor film 30 that may occur during the removal of the semiconductor material 40 can be suppressed.

[0105] On the other hand, when the number of cycles is the target number of cycles (in ​ S6 is "Yes"), the film thickness of the semiconductor film 30 has reached the target film thickness, so the current process ends.

[0106] The processed substrate 10 is used, for example, in a process of etching only the oxide film 13 among the nitride film 11 and the oxide film 13. In this process, the semiconductor film 30 is used as a protective film for protecting the nitride film 11 when etching the oxide film 13. The semiconductor film 30 protects the nitride film 11, and thereby can also protect an unillustrated conductive film formed between the nitride film 11 and the base substrate 14 in advance.

[0107] As ​ shown, fluorine adsorption and step formation (S3) are performed at a temperature lower than that when forming the semiconductor film 30 (S4). In S3, rapid etching of the nitride film 11 can be suppressed. As a result, the height H of the step surface 15 can be accurately managed during etching. In addition, etching non-uniformity of the nitride film 11 can be reduced.

[0108] Among them, as ​ shown, fluorine adsorption and step formation (S3) can be performed at the same temperature as when forming the semiconductor film 30 (S4). When changing from S3 to S4, there is no time for waiting for temperature change, so the productivity can be improved.

[0109] When S3 is carried out at the same temperature as S4, for example, F2 gas is used as the fluorine-containing gas in S3. F2 gas can also etch the native oxide film 12 in the temperature range of 350°C to 400°C, so it can also be used in S2. When switching from S2 to S3, there is no time waiting for gas switching, and there is also no time waiting for temperature change, so the productivity can be further improved.

[0110] F2 gas removes the native oxide film 12 in S2, and then selectively etches the nitride film 11 among the nitride film 11 and the oxide film 13 in S3. The etching rate of the nitride film 11 is faster than that of the native oxide film 12 and the oxide film 13. In addition, F2 gas adsorbs fluorine 20 on the substrate 10 in S3.

[0111] In addition, the film formation method may not include ​ a part of the multiple processes shown. For example, the film formation method may not include the removal of the semiconductor material (S5). In this case, the film formation method only includes the formation of the semiconductor film once (S4). In addition, as described above, when the substrate 10 without the native oxide film 12 is prepared by preparing the substrate 10 (S1), of course, the removal of the native oxide film 12 (S2) is not required.

[0112] Next, with reference to ​ to explain the film formation apparatus 100 for implementing ​ the film formation method shown. The film formation apparatus 100 is a batch-type vertical heat treatment apparatus for uniformly heat-treating a plurality of substrates.

[0113] The film formation apparatus 100 includes a processing container 110, a substrate holding unit 120, a heating unit 130, a gas supply unit 140, a gas discharge unit 150, and a control unit 160. The processing container 110 houses the substrate 10. The substrate holding unit 120 holds the substrate 10 inside the processing container 110. The heating unit 130 heats the substrate 10 held by the substrate holding unit 120. The gas supply unit 140 supplies gas into the processing container 110. The gas discharge unit 150 discharges gas from the inside of the processing container 110. The control unit 160 controls the heating unit 130, the gas supply unit 140, and the gas discharge unit 150 to implement ​ the film formation method shown.

[0114] The processing container 110 is a vertical double-layer tube, having a cylindrical inner tube 111 and a cylindrical outer tube 112 covering the outside of the inner tube 111. The inner tube 111 has an opening at the lower end and a horizontal top at the upper end. The outer tube 112 has an opening at the lower end and a dome-shaped top at the upper end. The inner tube 111 and the outer tube 112 are formed of, for example, quartz or silicon carbide.

[0115] The processing container 110 also has a manifold 114 with a cylindrical shape. The manifold 114 is formed of, for example, stainless steel. A flange portion 115 is formed at the upper end of the manifold 114. The lower end of the outer tube 112 is provided at the flange portion 115. A sealing member 116 such as an O-ring is disposed between the flange portion 115 and the lower end of the outer tube 112. A circular support portion 117 is provided on the inner wall of the upper portion of the manifold 114. The lower end of the inner tube 111 is provided at the support portion 117.

[0116] The processing container 110 also has a lid 118. The lid 118 closes the opening at the lower end of the manifold 114. A sealing member 119 such as an O-ring is disposed between the lid 118 and the lower end of the manifold 114. The lid 118 is formed of, for example, stainless steel. A through hole penetrating the lid 118 in the vertical direction is formed at the central portion of the lid 118. A rotating shaft 171 is disposed in the through hole. The gap between the lid 118 and the rotating shaft 171 is sealed by a magnetic fluid seal portion 172. The lower end portion of the rotating shaft 171 is rotatably supported by the arm 182 of the lifting portion 181. A rotating plate 173 is provided at the upper end portion of the rotating shaft 171. A substrate holding portion 120 is provided on the rotating plate 173 via a heat insulating table 121.

[0117] The substrate holding portion 120 holds a plurality of substrates 10 at intervals in the vertical direction. The plurality of substrates 10 are each held horizontally. When the lifting portion 181 is raised, the lid 118 and the substrate holding portion 120 are raised, and the substrate holding portion 120 is carried into the interior of the processing container 110, and the opening at the lower end of the processing container 110 is sealed by the lid 118. Further, when the lifting portion 181 is lowered, the lid 118 and the substrate holding portion 120 are lowered, and the substrate holding portion 120 is carried out to the outside of the processing container 110. Further, when the rotating shaft 171 is rotated, the substrate holding portion 120 rotates together with the rotating plate 173.

[0118] The heating portion 130 heats the substrate 10 held by the substrate holding portion 120. The heating portion 130 is formed in a cylindrical shape outside the processing container 110. The heating portion 130 is, for example, an electric heater.

[0119] The gas supply portion 140 supplies gas into the processing container 110. The gas supply portion 140 supplies the gas used in ​ S2, S3, S4, and S5 into the processing container 110. For example, the gas supply portion 140 supplies NH3 gas, HF gas, F2 gas, Si2H6 gas, Cl2 gas, and N2 gas into the processing container 110. In addition, as described above, there is no particular limitation on the type of gas.

[0120] The gas supply unit 140 has a vertical gas supply pipe 141 inside the processing container 110. The gas supply pipe 141 has a plurality of gas supply ports 142 spaced apart in the vertical direction. The plurality of gas supply ports 142 eject gas horizontally. In ​ only one gas supply pipe 141 is illustrated, but a plurality of gas supply pipes 141 are provided corresponding to a plurality of types of gas. In addition, it is possible that one gas supply pipe 141 ejects a plurality of types of gas in sequence. Alternatively, it is possible that a plurality of gas supply pipes 141 eject the same type of gas simultaneously.

[0121] The gas supply unit 140 has a gas supply source 143. The gas supply source 143 supplies gas to the gas supply pipe 141 via a flow controller 144 and an on-off valve 145. The flow controller 144 controls the flow rate of the gas. The on-off valve 145 switches between the supply and the stop of the gas supply. The gas supply source 143, the flow controller 144, and the on-off valve 145 are each illustrated as one in ​ but a plurality of each are provided corresponding to a plurality of types of gas.

[0122] The gas discharge unit 150 discharges gas from the inside of the processing container 110. In order to exhaust the inside of the inner pipe 111, an exhaust port 113 is formed in the inner pipe 111. The exhaust port 113 is arranged to face the gas supply port 142. The gas ejected horizontally from the gas supply port 142 descends along the inner wall of the outer pipe 112 after passing through the exhaust port 113 and is exhausted from the exhaust pipe 151.

[0123] The gas discharge unit 150 has an exhaust pipe 151, a vacuum pump 152, and a pressure controller 153. The exhaust pipe 151 connects the exhaust port of the manifold 114 to the vacuum pump 152. The vacuum pump 152 sucks gas from the inside of the processing container 110. The pressure controller 153 is provided in the middle of the exhaust pipe 151 and controls the air pressure inside the processing container 110.

[0124] The control unit 160 is, for example, a computer and includes a CPU (Central Processing Unit) 161 and a storage medium 162 such as a memory. Programs for controlling various processes executed in the film forming apparatus 100 are stored in the storage medium 162. The control unit 160 controls the operation of the film forming apparatus 100 by causing the CPU 161 to execute the programs stored in the storage medium 162.

[0125] In addition, the film forming apparatus 100 is not limited to ​The vertical heat treatment apparatus shown. For example, the film forming apparatus 100 may also be a single wafer type apparatus that processes the substrate 10 one by one. Additionally, the film forming apparatus 100 may also be a semi-batch type apparatus. The semi-batch type apparatus rotates a plurality of substrates 10 arranged around the rotation center line of the rotating table together with the rotating table, and causes the plurality of substrates 10 to sequentially pass through a plurality of regions where different gases are supplied.

[0126] The embodiments of the film forming method and the film forming apparatus according to the present disclosure have been described above, but the present disclosure is not limited to the above embodiments and the like. Various changes, corrections, substitutions, additions, deletions, and combinations can be made within the scope described in the claims. These also naturally fall within the technical scope of the present disclosure.

Claims

1. A film forming method, comprising the following steps: Supplying a fluorine-containing gas to a substrate in which a region where a nitride film is exposed and a region where an oxide film is exposed are adjacent, causing fluorine to adsorb to the substrate, and selectively etching the nitride film among the nitride film and the oxide film so that the surface of the nitride film is recessed with respect to the surface of the oxide film to form a stepped surface on the side surface of the oxide film; and After the step of causing fluorine to adsorb to the substrate and forming the stepped surface, supplying a source gas containing a semiconductor material to the substrate, and selectively forming a semiconductor film on the nitride film among the nitride film and the oxide film.

2. The film forming method according to claim 1, wherein: The step of causing fluorine to adsorb to the substrate and forming the stepped surface is performed at a lower temperature than the step of selectively forming the semiconductor film on the nitride film.

3. The film forming method according to claim 1 or 2, wherein: The fluorine-containing gas is F2 gas or HF gas used together with NH3 gas.

4. The film forming method according to claim 1 or 2, wherein: The source gas contains at least one of Si and Ge.

5. The film forming method according to claim 1 or 2, wherein: The nitride film is a silicon nitride film, and the oxide film is a silicon oxide film.

6. The film forming method according to claim 1 or 2, wherein: Before the step of causing fluorine to adsorb to the substrate and forming the stepped surface, there is also a step of removing the native oxide film of the nitride film to expose the nitride film.

7. The film forming method according to claim 6, wherein: NH3 gas and HF gas are used to remove the native oxide film.

8. The film forming method according to claim 1 or 2, wherein: After the step of selectively forming the semiconductor film on the nitride film, there is also a step of supplying a halogen-containing gas to the substrate to remove the semiconductor material deposited on the oxide film.

9. The film forming method according to claim 8, wherein: The halogen-containing gas does not contain fluorine.

10. The film forming method according to claim 8, wherein: It includes the following steps that are repeatedly performed: the step of selectively forming the semiconductor film on the nitride film; and the step of removing the semiconductor material deposited on the oxide film.

11. A film forming apparatus, comprising: A processing container that houses a substrate; A substrate holding part that holds the substrate inside the processing container; A heating part that heats the substrate held by the substrate holding part; A gas supply part that supplies gas to the inside of the processing container; A gas discharge part that discharges gas from the inside of the processing container; and A control part that controls the heating part, the gas supply part, and the gas discharge part to implement the film forming method according to any one of claims 1 to 10.

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