Substrate processing method and substrate processing apparatus

Abstract

This invention provides a technique for selectively etching a portion of the substrate surface while suppressing damage to another portion of the substrate surface. [Solution] The substrate processing method comprises: preparing a substrate having an oxide film containing oxygen and a non-oxide film substantially free of oxygen in different regions of its surface; modifying the surface of the oxide film with a modifying gas in order to etch the surface of the oxide film with an etching gas; selectively forming an etching protective film on the surface of the non-oxide film on the surface of the oxide film modified with the modifying gas; and etching the surface of the oxide film modified with the modifying gas with the etching gas while protecting the surface of the non-oxide film from the etching gas with the etching protective film.

Description

Technical Field

[0001] The present disclosure relates to a substrate processing method and a substrate processing apparatus.

Background Art

[0002] The atomic layer etching (ALE) described in Patent Document 1 alternately repeats reforming the surface of a silicon oxide film with a CF4 gas in which the surface is plasmaized and etching the surface of the reformed silicon oxide film with a H2 gas in which the surface is plasmaized.

Prior Art Documents

Patent Documents

[0006] According to one embodiment of the present disclosure, when selectively etching a portion of the substrate surface, damage to another portion of the substrate surface can be suppressed. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 is a flowchart showing a substrate processing method according to one embodiment. [Figure 2] Figure 2 is a flowchart showing an example of S103 in Figure 1. [Figure 3] Figure 3 is a flowchart showing an example of S107 in Figure 1. [Figure 4] Figure 4 is a cross-sectional view showing a substrate processing method according to one embodiment. [Figure 5] Figure 5 is a plan view showing a substrate processing apparatus according to one embodiment. [Figure 6] Figure 6 is a cross-sectional view showing an example of the first processing unit. [Modes for carrying out the invention]

[0008] Embodiments of this disclosure will be described below with reference to the drawings. In each drawing, identical or similar components are denoted by the same reference numerals, and their descriptions may be omitted. In this specification, the "~" indicating a numerical range means that the numbers before and after it are included as the lower and upper limits. Numerical ranges include rounded ranges. In this specification, the semiconductor element is Si or Ge.

[0009] First, a substrate processing method according to one embodiment will be described with reference to Figures 1 to 4. The substrate processing method includes, for example, steps S101 to S108 shown in Figure 1. However, the substrate processing method only needs to include steps S101 to S106, and does not need to include steps S107 to S108. Furthermore, the substrate processing method may include steps other than steps S101 to S108 shown in Figure 1.

[0010] Step S101 includes preparing the substrate W (see, for example, Figure 4). The substrate W has an oxide film W1 containing oxygen and a non-oxide film W2 substantially free of oxygen in different areas of its surface. The substrate W may be pre-cleaned so that both the oxide film W1 and the non-oxide film W2 are exposed in different areas of the substrate W's surface. In this embodiment, the surface of the substrate W is flat, but it may also be uneven. It is preferable that both the oxide film W1 and the non-oxide film W2 substantially do not contain boron (B). Substantially free of B means that the B content is 0 at% to 5 at%.

[0011] The oxide film W1 contains, for example, a compound of a semiconductor element and oxygen, or a compound of a metal and oxygen. The oxide film W1 preferably has an oxygen content of 20 at% to 60 at%. The oxide film W1 is not particularly limited, but examples include SiO film, TiO film, SnO film, WO film, or HfO film. Here, SiO film means a film containing silicon (Si) and oxygen (O). The atomic ratio of Si to O in the SiO film is not limited to 1:2. Similarly, for films other than SiO, such as TiO film, SnO film, WO film, and HfO film, the meaning is that they contain each element, and are not limited to stoichiometric ratios.

[0012] The non-oxide film W2 may contain, for example, only semiconductor elements, compounds of semiconductor elements and nitrogen, only metals, or compounds of metals and nitrogen. The non-oxide film W2 preferably has an oxygen content of 0 at% to 10 at%. The non-oxide film W2 is not particularly limited, but may include, for example, a Si film, a SiN film, or a SiGe film. If the non-oxide film W2 is a semiconductor film, the semiconductor film may be an amorphous film, a polycrystalline film, or a single-crystal film.

[0013] The oxide film W1 and the non-oxide film W2 are formed on a substrate (not shown). The substrate is a silicon wafer or a compound semiconductor wafer. The compound semiconductor wafer is, for example, a GaAs wafer, a SiC wafer, a GaN wafer, or an InP wafer. A functional film (not shown) may be formed between the oxide film W1 or the non-oxide film W2 and the substrate (not shown). The oxide film W1 may be formed when the film directly beneath it (e.g., a metal film or a semiconductor film) is naturally oxidized by contact with the atmosphere. The oxide film W1 may also be formed when the film directly beneath it (e.g., a metal film or a semiconductor film) is oxidized by a reaction with a reaction gas or the like.

[0014] Step S102 includes modifying the surface of the oxide film W1 with a modifying gas in order to selectively form an etching protective film WB on the surface of the non-oxide film W2 in step S103, and to etch the surface of the oxide film W1 with an etching gas in step S105 (see Figure 4). The modifying gas selectively modifies the surface of the oxide film W1 compared to the surface of the non-oxide film W2. The surface of the non-oxide film W2 is hardly modified. A modified film WA is formed on the surface of the oxide film W1 by reaction with the modifying gas or by adsorption of the modifying gas.

[0015] The modified film WA inhibits the formation of the etching protective film WB in step S103 and is removed by the etching gas in step S105. The modified film WA may also be removed by the etching gas in step S107c. A modified film WA having only one of the properties of (1) inhibiting the formation of the etching protective film WB in step S103 and (2) being removed by the etching gas in step S105 is not the modified film WA of this disclosure.

[0016] The modified gas is not particularly limited. For example, it contains boron and modifies the surface of the oxide film W1 into a boron oxide film. The boron oxide film is an example of the modified film WA. When boron contained in the modified gas夺取 oxygen from the oxide film W1, at least a part of the oxide film W1 is replaced with a boron oxide film. At this time, the semiconductor element or metal element contained in the oxide film W1 becomes a volatile compound and desorbs from the surface of the oxide film W1. In this case, the modified gas is BCl3, BBr3, BI3, B(CH3)3, B2H6, BF3, C9H 24 BN3, C3H9B, C6H 15 It is preferable to contain at least one of B, and B3N3H6.

[0017] When the oxide film W1 is a TiO film and the modified gas is BCl3 gas, the modification reaction represented by the following reaction formula (1) proceeds. (1) TiO2 + 4 / 3BCl3(g) → 2 / 3B2O3 + TiCl4(g) The change in Gibbs energy in the modification reaction represented by the above reaction formula (1) is -27.0 kcal / mol at 100°C.

[0018] When the oxide film W1 is a SiO film and the modified gas is BCl3 gas, the modification reaction represented by the following reaction formula (2) proceeds. (2) SiO2 + 4 / 3BCl3(g) → 2 / 3B2O3 + SiCl4(g) The change in Gibbs energy in the modification reaction represented by the above reaction formula (2) is -9.8 kcal / mol at 100°C.

[0019] When the oxide film W1 is a SnO film and the modified gas is BCl3 gas, the modification reaction represented by the following reaction formula (3) proceeds. (3) SnO2 + 4 / 3BCl3(g) → 2 / 3B2O3 + SnCl4(g) The change in Gibbs energy in the modification reaction represented by the above reaction formula (3) is -46.2 kcal / mol at 100°C.

[0020] When the oxide film W1 is a WO film and the reforming gas is BCl3 gas, the reforming reaction represented by the following reaction equation (4) proceeds. (4)WO3+2BCl3(g)→B2O3+WCl6(g) The change in Gibbs free energy in the reforming reaction represented by the above reaction equation (4) is -13.3 kcal / mol at 100°C.

[0021] When the oxide film W1 is an HfO film and the reformed gas is BCl3 gas, the reforming reaction represented by the following reaction equation (5) proceeds. (5)HfO2+4 / 3BCl3(g)→2 / 3B2O3+HfCl4(g) The change in Gibbs free energy in the reforming reaction represented by the above reaction equation (5) is -16.4 kcal / mol at 100°C.

[0022] When the oxide film W1 is a SnO film and the reformed gas is B(CH3)3 gas, the reforming reaction represented by the following reaction equation (6) proceeds. (6)SnO2+4 / 3B(CH3)3(g)→2 / 3B2O3+Sn(CH3)4(g) The change in Gibbs free energy in the reforming reaction represented by the above reaction equation (6) is -28.2 kcal / mol at 100°C.

[0023] When the oxide film W1 is a SnO film and the reformed gas is B(C2H5)3 gas, the reforming reaction represented by the following reaction equation (7) proceeds. (7)SnO2+4 / 3B(C2H5)3(g)→2 / 3B2O3+Sn(C2H5)4(g) The change in Gibbs free energy in the reforming reaction represented by the above reaction equation (7) is -24.5 kcal / mol at 100°C.

[0024] When the oxide film W1 is a SnO film and the reformed gas is BBr3 gas, the reforming reaction represented by the following reaction equation (8) proceeds. (8)SnO2+4 / 3BBr3(g)→2 / 3B2O3+SnBr4(g) The change in Gibbs free energy in the reforming reaction represented by the above reaction equation (8) is -72.1 kcal / mol at 100°C.

[0025] When the oxide film W1 is a SnO film and the reforming gas is BI3 gas, the reforming reaction represented by the following reaction equation (9) proceeds. (9)SnO2+4 / 3BI3(g)→2 / 3B2O3+SnI4(g) The change in Gibbs free energy in the reforming reaction represented by the above reaction equation (9) is -113.4 kcal / mol at 100°C.

[0026] The more negative and larger the absolute value of the change in Gibbs free energy, the more easily the reforming reaction proceeds. To accelerate reforming, the reformed gas may be plasma-activated. Note that the above values ​​for the change in Gibbs free energy are for the case where the reformed gas is not plasma-activated.

[0027] In step S102, it is preferable to control the temperature of the substrate W to 100°C or higher in order to promote the modification reaction of the oxide film W1. The modification reaction proceeds more easily when the temperature of the substrate W is 100°C or higher. The temperature of the substrate W is preferably 200°C or higher. The temperature of the substrate W is preferably 800°C or lower.

[0028] Step S103 includes selectively forming an etching protective film WB on the surface of the non-oxide film W2 relative to the surface of the oxide film W1 modified in step S102 (the surface of the modified film WA) (see Figure 4). Step S103 includes supplying a source gas containing a desired element X and a reaction gas that reacts with adsorbents of the source gas to the substrate W. The source gas and reaction gas are supplied alternately or simultaneously. In this case, the etching protective film WB contains element X.

[0029] Step S103 includes, for example, steps S103a to S103e, as shown in Figure 2. Step S103 only needs to include at least steps S103a, S103c, and S103e; it does not need to include steps S103b and S103d. Steps S103a to S103e will be described below.

[0030] Step S103a includes supplying a raw material gas to the substrate W. The raw material gas preferably contains a compound of element X and a halogen. The halogen is fluorine, chlorine, bromine, or iodine. Element X is not particularly limited, but is preferably a metallic element, and more preferably a transition metal element. Element X is, for example, Ti, W, V, Al, Mo, Sn, Hf, Ta, Nb, Zr, In, Ga, or Sb. Specific examples of raw material gases include TiCl4, WCl6, WF6, VCl4, AlCl3, MoCl5, SnCl4, HfCl4, TaCl5, NbCl5, ZrCl4, InCl3, GaCl3, or SbCl3. Element X may also be a semiconductor element, specifically Si or Ge. The raw material gas is silicon halide gas or germanium halide gas. Specific examples of silicon halide gases include SiCl4, SiHCl3, SiH2Cl2, SiH3Cl, Si2Cl 6、 Examples include Si2HCl5, Si2Cl3CH3, SiCl3CCl3, SiCl3CH3, or SiH2I2. Specific examples of germanium halide gases include GeCl4. The source gas may be supplied together with a diluent gas. The diluent gas is, for example, Ar or N2.

[0031] Furthermore, the raw material gas may be a hydrogenation gas or an organic compound gas. The hydrogenation gas or organic compound gas contains a metal or semiconductor element. Examples of hydrogenation gases include SiH4, Si2H6, H2Se, GeH4, Ge2H6, H2Te, SbH3, or SnH4. Examples of organic compound gases include Al(CH3)3, Ti[N(CH3)2]4, Co(C5H5)2, Ru(C5H5)2, Ga(CH3)3, In(CH3)3, Sn(C2H5)4, Sn(i-C3H7)4, Mg(C5H5)2, or Si(CH3)4.

[0032] Step S103b includes supplying a purge gas to the substrate W. The purge gas purges any excess raw material gas that was not adsorbed on the substrate W in step S103a. As the purge gas, for example, a noble gas such as Ar gas or N2 gas can be used.

[0033] Step S103c includes supplying a reaction gas to the substrate W. The reaction gas reacts with element X contained in the adsorbed material of the raw material gas to form an etching protective film WB. The etching protective film WB contains element X. Examples of reaction gases include oxygen-containing gases, nitrogen-containing gases, or hydrogen-containing gases. Oxygen-containing gases contain oxygen and form an oxide film of element X. Examples of oxygen-containing gases include O2, O3, CO2, N2O, NO, or H2O. Nitrogen-containing gases contain nitrogen and form a nitride film of element X. Examples of nitrogen-containing gases include NH3 or N2H4. Hydrogen-containing gases contain hydrogen and form a film (e.g., a metal film or a semiconductor film) mainly composed of element X. Examples of hydrogen-containing gases include H2 or H2S. The reaction gas may be supplied together with a diluent gas. Examples of diluent gases include Ar or N2.

[0034] Step S103c may include plasmaizing the reaction gas, and may also include supplying the plasmaized reaction gas to the substrate W. Plasmaizing the reaction gas can promote the formation of the etching protective film WB.

[0035] The reaction gas may be supplied not only in step S103c, but also in all of steps S103a to S103d. However, plasma formation of the reaction gas is performed only in step S103c. This is because plasma formation of the reaction gas makes it easier to react with adsorbed material of the raw material gas on the substrate W.

[0036] Step S103c may also include supplying O3 to the substrate W as a reaction gas without plasma formation.

[0037] Step S103d includes supplying a purge gas to the substrate W. The purge gas purges any excess reaction gas that did not react with the substrate W in step S103c. As the purge gas, for example, a noble gas such as Ar gas or N2 gas can be used.

[0038] Step S103e includes checking whether the fourth cycle has been performed N times (where N is an integer greater than or equal to 1). The fourth cycle includes steps S103a to S103d. N may be an integer greater than or equal to 2, and the fourth cycle may be performed repeatedly multiple times. The thickness of the etching protective film WB can be increased.

[0039] If the number of times the fourth cycle is performed is less than N (step S103e, NO), the thickness of the etching protective film WB is less than the target value, so the fourth cycle is performed again. N is preferably 10 or more, more preferably 20 or more. N is preferably 100 or less. The target value for the thickness of the etching protective film WB is preferably 1 nm or more, more preferably 5 nm or more.

[0040] On the other hand, when the number of times the fourth cycle is performed reaches N (step S103e, YES), the thickness of the etching protective film WB has reached the target value, and the current process is terminated.

[0041] The film deposition method shown in Figure 2 is the ALD (Atomic Layer Deposition) method, but the CVD (Chemical Vapor Deposition) method may also be used. In the ALD method, the supply of the raw material gas (step S103a) and the supply of the reaction gas (step S103c) are performed alternately. On the other hand, in the CVD method, the supply of the raw material gas and the reaction gas are performed simultaneously.

[0042] To inhibit the formation of the etching protective film (WB) on the surface of the boron oxide film, it is important that the adsorption of the source gas onto the boron oxide film is weak, and as a result, the adsorbed source gases on the surface of the boron oxide film are desorbed without advancing the film formation reaction (formation of the etching protective film WB). Alternatively, it is important that the adsorption of the source gas onto the surface of the boron oxide film does not occur, or that the dissociation of the source gas on the surface of the boron oxide film is unlikely to occur. If the dissociation of the source gas occurs, the substrate processing reaction will proceed more easily.

[0043] Since the boron oxide film contains boron, it is thought that adsorption of the source gas does not occur on the surface of the boron oxide film, or if it does occur, it is weak, or that dissociation of the source gas is unlikely to occur. As a result, the formation of the etching protective film WB is inhibited on the surface of the boron oxide film.

[0044] On the other hand, since the non-oxide film W2 substantially does not contain boron, it is thought that the source gas is strongly adsorbed on the surface of the non-oxide film W2, or that dissociation of the source gas is likely to occur. As a result, it is thought that the formation of the etching protective film WB progresses on the surface of the non-oxide film W2.

[0045] The raw material gas is preferably a halide. Gases containing halogens, such as TiCl4 and Si2Cl6, are less likely to decompose due to the heat of the substrate W compared to hydrogenated gases such as Si2H6 and organometallic gases such as Ti[N(CH3)2]4. If the raw material gas decomposes after being adsorbed onto the boron oxide film, the formation of the etching protective film WB will proceed. Therefore, in order to inhibit the formation of the etching protective film WB on the surface of the boron oxide film, a halogen-containing gas is suitable as the raw material gas for the etching protective film WB.

[0046] However, the raw material gas may be a hydrogenation gas or an organic compound gas. Even if the raw material gas is a hydrogenation gas or an organic compound gas, the formation of the etching protective film WB is considered to be difficult on the surface of the boron oxide film. This is because the incubation time is longer on the surface of the boron oxide film than on the surface of the non-oxide film W2. Incubation time is the time from the start of the film formation process (e.g., the start of supplying the raw material gas or reaction gas) until the actual film formation begins. The thickness of the etching protective film WB is set so as to prevent damage to the non-oxide film W2 when etching the boron oxide film in the subsequent etching steps (steps S105 and S107c). If the non-oxide film W2 is not exposed by pinholes or the like when etching the boron oxide film, the thickness of the etching protective film WB may be about 1 nm. If the thickness of the etching protective film WB is about 1 nm, the hydrogenation gas and organic compound gas can selectively form the etching protective film WB on the non-oxide film W2 due to the difference in incubation time.

[0047] In plasma CVD, where both the source gas and the reaction gas are plasma-activated, reactive species such as ions or radicals are generated from the dissociation of the source gas. These reactive species from the source gas are highly reactive, and the substrate processing reaction proceeds easily not only on the surface of the non-oxide film W2 but also on the surface of the boron oxide film, making it difficult to selectively form the etching protective film WB on the non-oxide film W2. Therefore, it is preferable not to plasma-activate the source gas, and it is important to use thermal ALD, plasma ALD, or thermal CVD.

[0048] In steps S103a to S103d above, the temperature of the substrate W may be controlled to 100°C or higher in order to promote the desorption of the raw material gas on the surface of the boron oxide film. If the temperature of the substrate W is below 100°C, the desorption of the raw material gas will not occur sufficiently on the surface of the boron oxide film, and the raw material gas will be physically adsorbed, resulting in the formation of the etching protective film WB on the surface of the boron oxide film as well. The temperature of the substrate W is preferably 200°C or higher. The temperature of the substrate W is preferably 800°C or lower.

[0049] Step S104 includes checking whether the first cycle has been performed K times (where K is an integer greater than or equal to 1). The first cycle includes supplying reforming gas (step S102) and forming the etching protective film WB (step S103). K may be an integer greater than or equal to 2, and the first cycle may be repeated multiple times. In step S103, if the reforming film WA is damaged by plasma or the like before the thickness of the etching protective film WB reaches the target value, and the surface of the oxide film W1 is exposed, it is effective to repeat the first cycle.

[0050] If the number of times the first cycle is performed is less than K (step S104, NO), the thickness of the etching protective film WB is less than the target value, so the first cycle is performed again. K is preferably 1 or more, more preferably 2 or more. K is preferably 10 or less. The target value for the thickness of the etching protective film WB is preferably 1 nm or more, more preferably 5 nm or more.

[0051] On the other hand, when the number of times the first cycle is performed reaches K (step S104, YES), the thickness of the etching protective film WB has reached the target value, so step S105 is performed. Note that if K is an integer of 2 or more, that is, if the first cycle is performed repeatedly, the etching protective film WB is preferably a non-oxide film that substantially does not contain oxygen. The non-oxide film preferably has an oxygen content of 0 at% to 10 at%. If the etching protective film WB is a non-oxide film, the reforming gas does not reform the etching protective film WB in step S102 from the second time onward.

[0052] Step S105 involves etching the modified film WA with an etching gas while protecting the surface of the non-oxide film W2 from the etching gas with an etching protective film WB (see Figure 4). The etching gas is not particularly limited, but for example, it may be a plasma-formed noble gas. The plasma-formed noble gas sputters the modified film WA, promoting its volatilization. As a result, etching of the modified film WA progresses. The noble gas may include He, Ne, Ar, Kr, or Xe.

[0053] The etching gas is not limited to noble gases. The etching gas may include H2, O2, COS, NH3, SO2, CO2, CO, CH4, NO2, NO, or N2, etc. If the modified film WA is a boron oxide film, the etching gas may include Cl2, F2, HF, XeF2, ClF3, BrF3, HCl, Br2, HBr, I2, HI, NF3, SOCl2, SO2Cl2, or SF6. Also, if the modified film WA is a boron oxide film, the etching gas may include CF4, CH3F, CHF3, C4F6, C4F8, CH3Cl, COCl2, or CH3Br. These etching gases may be plasma-generated.

[0054] The etching gas may etch not only the modified film WA but also the etching protective film WB. In the latter case, it is sufficient that the etching protective film WB remains intact and the surface of the non-oxide film W2 is not exposed. It is sufficient that the surface of the non-oxide film W2 is not damaged by the etching gas.

[0055] ALE is a method that alternately repeats the process of forming a modified film by supplying a modified gas and removing the modified film by supplying an etching gas. If the modified gas selectively reacts with or adsorbs to the surface of, for example, an oxide film W1 to form a modified film, and hardly modifies the surface of the non-oxide film W2, the oxide film W1 can be selectively etched. However, if the surface of the non-oxide film W2 is exposed, it is possible that the non-oxide film W2 may be damaged by the etching gas. Also, if the etching gas is a plasma-generated noble gas, it is possible that the non-oxide film W2 may be damaged by sputtering if ions generated in the plasma collide with it.

[0056] If the oxide film W1 to be etched contains transition metal elements, such as a high-k film, then high substrate temperatures or high ion energy are required to proceed with the etching of the oxide film W1. Therefore, if the surface of the non-oxide film W2 is exposed, it is considered that preventing damage to the non-oxide film W2 will be more difficult.

[0057] According to this embodiment, by modifying the surface of the oxide film W1, the formation of the etching protective film WB on the surface of the oxide film W1 is inhibited, and the etching protective film WB is selectively formed on the surface of the non-oxide film W2. Subsequently, the modified film WA is removed while protecting the surface of the non-oxide film W2 with the etching protective film WB, thereby suppressing damage to the non-oxide film W2.

[0058] Step S106 includes checking whether the second cycle has been performed L times (where L is an integer greater than or equal to 1). The second cycle includes supplying reformed gas (step S102), forming an etching protective film WB (step S103), and supplying etching gas (step S105). L may be an integer greater than or equal to 2, and the second cycle may be repeated multiple times. At the end of step S105, if the thickness of the etching protective film WB does not exceed a set value, it is effective to repeat the second cycle.

[0059] If the number of times the second cycle is performed is less than L (step S106, NO), the etching amount of the oxide film W1 is less than the target value, and the thickness of the etched protective film WB is less than the set value (less than 1 nm), so the second cycle is performed again. L is preferably 10 or more, more preferably 20 or more. L is preferably 100 or less.

[0060] On the other hand, if the number of executions of the second cycle reaches L (step S106, YES), and the etching amount of the oxide film W1 is less than the target value, and the thickness of the etching protective film WB is greater than or equal to the set value (1 nm or more), then step S107 is performed. If the number of executions of the second cycle reaches L (step S106, YES), and the etching amount of the oxide film W1 has reached the target value, then steps S107 to S108 do not need to be performed.

[0061] Furthermore, if L is an integer of 2 or more, that is, if the second cycle is repeated, the etching protective film WB is preferably a non-oxide film that substantially does not contain oxygen. The non-oxide film preferably has an oxygen content of 0 at% to 10 at%. If the etching protective film WB is a non-oxide film, the reformed gas will not reform the etching protective film WB in the second and subsequent steps S102.

[0062] Step S107, as shown in Figure 3, includes, for example, steps S107a to S107e. Step S107 only needs to include at least steps S107a, S107c, and S107e, and does not need to include steps S107b and S107d. Steps S107a to S107e will be described below.

[0063] Step S107a includes supplying a reforming gas to the substrate W. The reforming gas is preferably the same reforming gas used in S102. The reforming gas is not particularly limited, but for example, it contains boron and reforms the surface of the oxide film W1 into a boron oxide film. In this case, the reforming gas is BCl3, BBr3, BI3, B(CH3)3, B2H6, BF3, C9H 24BN3, C3H9B, C6H 15 Preferably, it contains at least one of B and B3N3H6.

[0064] Step S107b includes supplying a purge gas to the substrate W. The purge gas purges any excess reforming gas that was not used to reform the substrate W in step S107a. As the purge gas, for example, a noble gas such as Ar gas or N2 gas may be used.

[0065] Step S107c includes supplying an etching gas to the substrate W. The etching gas is preferably the same etching gas used in S105. Step S107c includes etching the modified film WA with the etching gas while protecting the surface of the non-oxide film W2 from the etching gas with an etching protective film WB (see Figure 4). The etching gas is not particularly limited, but for example, it may be a plasma-formed noble gas. The plasma-formed noble gas sputters the modified film WA and promotes volatilization. As a result, etching of the modified film WA progresses. The noble gas may include He, Ne, Ar, Kr, or Xe.

[0066] The etching gas is not limited to noble gases. The etching gas may include H2, O2, COS, NH3, SO2, CO2, CO, CH4, NO2, NO, or N2, etc. If the modified film WA is a boron oxide film, the etching gas may also include Cl2, F2, HF, XeF2, ClF3, BrF3, HCl, Br2, HBr, I2, HI, NF3, SOCl2, SO2Cl2, or SF6. Furthermore, if the modified film WA is a boron oxide film, the etching gas may also include CF4, CH3F, CHF3, C4F6, C4F8, CH3Cl, COCl2, or CH3Br. These etching gases may be plasma-generated.

[0067] Step S107d includes supplying a purge gas to the substrate W. The purge gas purges any excess etching gas that did not react with the substrate W in step S107c. As the purge gas, for example, a noble gas such as Ar gas or N2 gas can be used.

[0068] Step S107e includes checking whether the fifth cycle has been performed J times (where J is an integer greater than or equal to 1). The fifth cycle includes steps S107a to S107d. J may be an integer greater than or equal to 2, and the fifth cycle may be repeated multiple times. The amount of etching of the oxide film W1 can be increased.

[0069] If the thickness of the etched protective film WB remains, for example, 1 nm or more, and the number of times the fifth cycle is performed is less than J (step S107e, NO), the etching amount of the oxide film W1 is less than the target value, so the fifth cycle is performed again. J is preferably 10 or more, more preferably 20 or more. J is preferably 100 or less.

[0070] On the other hand, if the number of executions of the fifth cycle reaches J (step S107e, YES), the current process is terminated. Reaching J executions of the fifth cycle may include (1) the etching amount of the oxide film W1 reaching the target value, or (2) the etching amount of the oxide film W1 not reaching the target value, but the thickness of the etching protective film WB becoming less than 1 nm.

[0071] Step S108 includes checking whether the third cycle has been performed M times (where M is an integer greater than or equal to 1). The third cycle includes supplying reformed gas (step S102), forming an etching protective film WB (step S103), and supplying etching gas (step S105), and thereafter including supplying reformed gas (step S107a) and etching gas (step S107c) without intervening the formation of the etching protective film WB. M may be an integer greater than or equal to 2, and the third cycle may be performed repeatedly multiple times. The amount of etching of the oxide film W1 can be increased.

[0072] If the number of times the third cycle is performed is less than M (step S108, NO), the etching amount of the oxide film W1 is less than the target value, so the third cycle is performed again. M is preferably 1 or more, more preferably 2 or more. M is preferably 10 or less.

[0073] On the other hand, when the number of times the third cycle is performed reaches M (step S108, YES), the etching amount of the oxide film W1 has reached the target value, and the current process is terminated. Note that if M is an integer of 2 or more, that is, if the third cycle is repeated, the etching protective film WB is preferably a non-oxide film that substantially does not contain oxygen. The non-oxide film preferably has an oxygen content of 0 at% to 10 at%. If the etching protective film WB is a non-oxide film, the reformed gas does not reform the etching protective film WB in step S102 from the second time onward.

[0074] As described above, the substrate processing method of this embodiment includes steps S102, S103, and S105. Step S102 includes modifying the surface of the oxide film W1 with a modifying gas in order to etch the surface of the oxide film W1 with an etching gas in step S105. Step S103 includes selectively forming an etching protective film WB on the surface of the non-oxide film W2 on the surface of the oxide film W1 modified in step S102. Step S105 includes etching the surface of the oxide film W1 modified with the modifying gas with an etching gas while protecting the surface of the non-oxide film W2 from the etching gas with the etching protective film WB.

[0075] According to this embodiment, in step S102, the film formation inhibiting properties of the modified oxide film W1 surface can be utilized to selectively form an etching protective film WB on the surface of the non-oxide film W2 relative to the surface of the oxide film W1 in step S103. As a result, in step S105, the etching protective film WB can protect the surface of the non-oxide film W2 from etching gas. Therefore, when selectively etching a part of the substrate surface (the surface of the oxide film W1), damage to another part of the substrate surface (the surface of the non-oxide film W2) can be suppressed.

[0076] In this embodiment, the reforming gas contains boron and reforms the surface of the oxide film W1 into a boron oxide film, but the technology of this disclosure is not limited to the above embodiment. For example, the reforming gas may contain halogen and adsorb halogen onto the surface of the oxide film W1. The reforming gas selectively reforms the surface of the oxide film W1 compared to the surface of the non-oxide film W2. The surface of the non-oxide film W2 hardly adsorbs halogen.

[0077] The reformed gas may contain halogens without substantially containing carbon, and the halogens may be adsorbed onto the surface of the oxide film W1. In this case, the reformed gas preferably contains at least one of Cl2, F2, HF, XeF2, ClF3, BrF3, HCl, Br2, HBr, I2, HI, NF3, SOCl2, SO2Cl2, and SF6.

[0078] The reformed gas may contain a compound of carbon and halogen, and halogen may be adsorbed onto the surface of the oxide film W1. In this case, the reformed gas preferably contains at least one of CF4, CH3F, CHF3, C4F6, C4F8, CH3Cl, COCl2, and CH3Br. If the reformed gas contains carbon, a carbon film may be formed on the surface of the non-oxide film W2.

[0079] A halogen-containing reforming gas modifies the surface of the oxide film W1 by adsorbing halogens onto the surface, thereby forming a halogen-containing film. The halogen-containing film is an example of a reformed film WA. It is thought that halogen-containing reforming gases are more readily adsorbed onto the surface of the oxide film W1 than onto the surface of the non-oxide film W2, thus forming a halogen-containing film. Furthermore, reforming gases containing carbon and halogen compounds remove oxygen from the surface of the oxide film W1. The carbon contained in the reforming gas volatilizes as CO and CO2. As a result, it is thought that halogen elements are adsorbed onto the surface of the oxide film W1, forming a halogen-containing film.

[0080] To inhibit the formation of an etching protective film WB on the surface of a halogen-containing film, it is important that halogen elements are sufficiently adsorbed onto the surface of the oxide film W1. If halogen elements are sufficiently adsorbed onto the surface of the oxide film W1, there will be less exposed surface area of ​​the oxide film W1 where the source gas can be adsorbed. It is thought that the source gas will not easily adsorb onto the surface of the halogen-containing film and will instead desorb.

[0081] On the other hand, the surface of the non-oxide film W2 shows almost no halogen adsorption compared to the surface of the oxide film W1. Therefore, it is thought that the raw material gas for the etching protective film WB is adsorbed onto the exposed surface of the non-oxide film W2, and the formation of the etching protective film WB proceeds. On the surface of the oxide film W1, a halogen-containing film is formed due to halogen adsorption, so the formation of the etching protective film WB is delayed.

[0082] The incubation time for the etching protective film WB is longer on the surface of the oxide film W1 compared to the surface of the non-oxide film W2. This difference in incubation time is amplified by selectively adsorbing halogen onto the surface of the oxide film W1. Therefore, in step S103, the etching protective film WB can be selectively formed on the surface of the non-oxide film W2 compared to the surface of the oxide film W1 on which halogen has been adsorbed.

[0083] The etching gas for the halogen-containing film is not particularly limited, but is preferably a plasma-formed rare gas. The plasma-formed rare gas collides with the halogen-containing film, promoting the formation of volatile metal or semiconductor element halides. The plasma-formed rare gas also promotes the desorption of metal or semiconductor element halides by sputtering. As a result, etching of the halogen-containing film progresses. The rare gas includes He, Ne, Ar, Kr, or Xe.

[0084] Etching gases are not limited to noble gases. Etching gases include H2, O2, COS, NH3, SO2, CO2, CO, and CH4. 4、 The etching gas may contain NO2, NO, or N2, etc. These etching gases may be plasma-activated. If the modified film WA is a halogen-containing film, the etching gas may be a ligand-exchange gas containing a highly volatile organometallic gas or a metal halide gas. The ligand-exchange gas exchanges ligands with the metal or semiconductor element of the oxide film W1 that is bonded to the halogen of the halogen-containing film. As a result, a highly volatile organic compound gas or halide gas containing the metal or semiconductor element of the oxide film W1 is produced. This allows the surface of the oxide film W1 to be etched. Examples of ligand-exchange gases include Al(CH3)2Cl, Al(CH3)3, SiCl4, TiCl4, or Sn(CH3COCHCOCH3)2.

[0085] Next, with reference to Figure 5, a substrate processing apparatus 100 that implements the above substrate processing method will be described. As shown in Figure 5, the substrate processing apparatus 100 has a first processing unit 200A, a second processing unit 200B, a third processing unit 200C, a fourth processing unit 200D, a transport unit 400, and a control unit 500. The first processing unit 200A performs step S102 in Figure 1. The second processing unit 200B performs step S103 in Figure 1. The third processing unit 200C performs step S105 in Figure 1. The fourth processing unit 200D performs step S107 in Figure 1. It is also possible for the first processing unit 200A to perform all of steps S102, S103, S105, and S107 in Figure 1.

[0086] The transport unit 400 transports the substrate W to the first processing unit 200A, the second processing unit 200B, the third processing unit 200C, and the fourth processing unit 200D. The transport unit 400 has a first transport chamber 401 and a first transport mechanism 402. The internal atmosphere of the first transport chamber 401 is an atmospheric atmosphere. The first transport mechanism 402 is provided inside the first transport chamber 401. The first transport mechanism 402 includes an arm 403 for holding the substrate W and travels along a rail 404. The rail 404 extends in the direction of the arrangement of the carriers C.

[0087] Furthermore, the transport unit 400 includes a second transport chamber 411 and a second transport mechanism 412. The internal atmosphere of the second transport chamber 411 is a vacuum atmosphere. The second transport mechanism 412 is provided inside the second transport chamber 411. The second transport mechanism 412 includes an arm 413 for holding the substrate W, and the arm 413 is arranged to be movable in the vertical and horizontal directions and rotatable around a vertical axis. The first processing unit 200A, the second processing unit 200B, the third processing unit 200C, and the fourth processing unit 200D are connected to the second transport chamber 411 via different gate valves G.

[0088] Furthermore, the conveying section 400 has a load lock chamber 421 between the first conveying chamber 401 and the second conveying chamber 411. The internal atmosphere of the load lock chamber 421 is switched between a vacuum atmosphere and an atmospheric atmosphere by a pressure regulating mechanism (not shown). This allows the inside of the second conveying chamber 411 to always be maintained in a vacuum atmosphere. It also prevents gas from flowing from the first conveying chamber 401 into the second conveying chamber 411. Gate valves G are provided between the first conveying chamber 401 and the load lock chamber 421, and between the second conveying chamber 411 and the load lock chamber 421.

[0089] The control unit 500 is, for example, a computer and has an arithmetic unit 501 such as a CPU (Central Processing Unit) and a storage unit 502 such as memory. The storage unit 502 stores programs that control various processes performed in the substrate processing apparatus 100. The control unit 500 controls the operation of the substrate processing apparatus 100 by causing the arithmetic unit 501 to execute the programs stored in the storage unit 502. The control unit 500 controls the first processing unit 200A, the second processing unit 200B, the third processing unit 200C, the fourth processing unit 200D and the transport unit 400 to carry out the above substrate processing method.

[0090] The control unit 500 includes an electronic circuit such as a CPU, FPGA (Field Programmable Gate Array), or ASIC (Application Specific Integrated Circuit), and performs various control operations described in this specification by executing instruction codes stored in memory or by designing the circuit for special applications.

[0091] Next, the operation of the substrate processing apparatus 100 will be described. First, the first transport mechanism 402 takes the substrate W from the carrier C, transports the removed substrate W to the load lock chamber 421, and exits the load lock chamber 421. Next, the internal atmosphere of the load lock chamber 421 is switched from an atmospheric atmosphere to a vacuum atmosphere. After that, the second transport mechanism 412 takes the substrate W from the load lock chamber 421 and transports the removed substrate W to the first processing unit 200A.

[0092] Next, the first processing unit 200A performs step S102 in Figure 1. After that, the second transport mechanism 412 removes the substrate W from the first processing unit 200A and transports the removed substrate W to the second processing unit 200B. During this time, the substrate W is protected in a vacuum atmosphere, and contamination of the substrate W by organic compounds in the atmosphere is suppressed.

[0093] Next, the second processing unit 200B performs step S103 in Figure 1. Then, the control unit 500 performs step S104 in Figure 1. If the number of times the first cycle has been performed has not reached K (step S104, NO), the second transport mechanism 412 removes the substrate W from the second processing unit 200B and transports the removed substrate W to the first processing unit 200A. After that, the first cycle is performed again.

[0094] On the other hand, when the number of executions of the first cycle reaches K (step S104, YES), the second transport mechanism 412 removes the substrate W from the second processing unit 200B and transports the removed substrate W to the third processing unit 200C. During this time, the substrate W can be protected in a vacuum atmosphere, and contamination of the substrate W by organic compounds in the atmosphere can be suppressed.

[0095] Next, the third processing unit 200C performs step S105 in Figure 1. Then, the control unit 500 performs step S106 in Figure 1. If the number of times the second cycle has been performed has not reached L (step S106, NO), the second transport mechanism 412 removes the substrate W from the third processing unit 200C and transports the removed substrate W to the first processing unit 200A. After that, the second cycle is performed again.

[0096] On the other hand, when the number of executions of the second cycle reaches L (step S106, YES), the second transport mechanism 412 removes the substrate W from the third processing unit 200C and transports the removed substrate W to the fourth processing unit 200D. During this time, the substrate W can be protected in a vacuum atmosphere, and contamination of the substrate W by organic compounds in the atmosphere can be suppressed.

[0097] Next, the fourth processing unit 200D performs step S107 in Figure 1. Then, the control unit 500 performs step S108 in Figure 1. If the number of times the third cycle has been performed has not reached M (step S108, NO), the second transport mechanism 412 removes the substrate W from the fourth processing unit 200D and transports the removed substrate W to the first processing unit 200A. After that, the third cycle is performed again.

[0098] On the other hand, when the number of executions of the third cycle reaches M (step S108, YES), the second transport mechanism 412 removes the substrate W from the fourth processing unit 200D, transports the removed substrate W to the load lock chamber 421, and exits the load lock chamber 421. Subsequently, the internal atmosphere of the load lock chamber 421 is switched from a vacuum atmosphere to an atmospheric atmosphere. After that, the first transport mechanism 402 removes the substrate W from the load lock chamber 421 and places the removed substrate W into the carrier C. Then, the processing of the substrate W is completed.

[0099] Next, the first processing unit 200A will be described with reference to Figure 6. Note that the configurations of the second processing unit 200B, the third processing unit 200C, and the fourth processing unit 200D are the same as those of the first processing unit 200A, and therefore their illustrations and descriptions are omitted.

[0100] The first processing unit 200A includes a substantially cylindrical, airtight processing container 210. An exhaust chamber 211 is provided in the center of the bottom wall of the processing container 210. The exhaust chamber 211 has a shape that protrudes downward, for example, a substantially cylindrical shape. An exhaust pipe 212 is connected to the exhaust chamber 211, for example, on the side of the exhaust chamber 211.

[0101] An exhaust source 272 is connected to the exhaust piping 212 via a pressure controller 271. The pressure controller 271 includes a pressure regulating valve, such as a butterfly valve. The exhaust piping 212 is configured to reduce the pressure inside the processing container 210 by the exhaust source 272. The pressure controller 271 and the exhaust source 272 constitute a gas discharge mechanism 270 that discharges gas from inside the processing container 210.

[0102] A transport opening 215 is provided on the side of the processing container 210. The transport opening 215 is opened and closed by a gate valve G. The substrate W is loaded and unloaded between the processing container 210 and the second transport chamber 411 (see Figure 5) through the transport opening 215.

[0103] A stage 220, which is a holding part for holding the substrate W, is provided inside the processing container 210. The stage 220 holds the substrate W horizontally with the surface to be etched facing upwards. The stage 220 is formed in a substantially circular shape in plan view and is supported by a support member 221. A substantially circular recess 222 is formed on the surface of the stage 220 for placing a substrate W, for example, with a diameter of 300 mm. The recess 222 has an inner diameter slightly larger than the diameter of the substrate W. The depth of the recess 222 is set to be approximately the same as the thickness of the substrate W, for example. The stage 220 is made of a ceramic material such as aluminum nitride (AlN). Alternatively, the stage 220 may be made of a metallic material such as nickel (Ni). Instead of the recess 222, a guide ring for guiding the substrate W may be provided on the peripheral edge of the surface of the stage 220.

[0104] A lower electrode 223, for example, grounded, is embedded in the stage 220. A heating mechanism 224 is embedded below the lower electrode 223. The heating mechanism 224 is powered by a power supply unit (not shown) based on a control signal from the control unit 500 (see Figure 5), and heats the substrate W placed on the stage 220 to a set temperature. If the entire stage 220 is made of metal, the entire stage 220 functions as the lower electrode, so the lower electrode 223 does not need to be embedded in the stage 220. The stage 220 is provided with a plurality of (e.g., three) lifting pins 231 for holding and raising and lowering the substrate W placed on the stage 220. The material of the lifting pins 231 may be, for example, ceramics such as alumina (Al2O3) or quartz. The lower ends of the lifting pins 231 are attached to a support plate 232. The support plate 232 is connected via a lifting shaft 233 to a lifting mechanism 234 located outside the processing container 210.

[0105] The lifting mechanism 234 is installed, for example, at the bottom of the exhaust chamber 211. The bellows 235 is provided between the opening 219 for the lifting shaft 233 formed on the lower surface of the exhaust chamber 211 and the lifting mechanism 234. The shape of the support plate 232 may be such that it can move up and down without interfering with the support member 221 of the stage 220. The lifting pin 231 is configured to move up and down between the upper surface of the stage 220 and the lower surface of the stage 220 by the lifting mechanism 234.

[0106] A gas supply unit 240 is provided on the top wall 217 of the processing container 210 via an insulating member 218. The gas supply unit 240 forms the upper electrode and faces the lower electrode 223. A high-frequency power supply 252 is connected to the gas supply unit 240 via a matching unit 251. By supplying high-frequency power of 100kHz to 2.45GHz, preferably 450kHz to 100MHz, from the high-frequency power supply 252 to the upper electrode (gas supply unit 240), a high-frequency electric field is generated between the upper electrode (gas supply unit 240) and the lower electrode 223, and a capacitively coupled plasma is generated. The plasma generation unit 250 that generates the plasma includes a matching unit 251 and a high-frequency power supply 252. Note that the plasma generation unit 250 is not limited to generating a capacitively coupled plasma, but may generate other plasmas such as inductively coupled plasma or remote plasma. Note that in steps where plasma is not generated, it is not necessary for the gas supply unit 240 to form the upper electrode, and the lower electrode 223 is also unnecessary.

[0107] The gas supply unit 240 includes a hollow gas supply chamber 241. On the lower surface of the gas supply chamber 241, numerous holes 242 are evenly arranged, for example, to distribute and supply the processing gas into the processing container 210. Above the gas supply chamber 241 in the gas supply unit 240, for example, a heating mechanism 243 is embedded. The heating mechanism 243 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 500.

[0108] A gas supply mechanism 260 is connected to the gas supply chamber 241 via a gas supply passage 261. The gas supply mechanism 260 supplies the gas used in the desired steps of Figure 1 to the gas supply chamber 241 via the gas supply passage 261. Although not shown, the gas supply mechanism 260 includes individual piping for each type of gas, on-off valves installed in the middle of the individual piping, and flow controllers installed in the middle of the individual piping. When the on-off valve opens the individual piping, gas is supplied from the supply source to the gas supply passage 261. The amount of gas supplied is controlled by the flow controller. On the other hand, when the on-off valve closes the individual piping, the supply of gas from the supply source to the gas supply passage 261 is stopped.

[0109] While embodiments of the substrate processing method and substrate processing apparatus relating to this disclosure have been described above, this disclosure is not limited to the above embodiments. Various changes, modifications, substitutions, additions, deletions, and combinations are possible within the scope of the claims. These also naturally fall within the technical scope of this disclosure. [Explanation of symbols]

[0110] W board W1 Oxide film W2 Non-oxide film WA modified membrane WB etching protective film

Claims

1. The method involves preparing a substrate having an oxide film containing oxygen and a non-oxide film substantially free of oxygen in different regions of its surface, In order to etch the surface of the oxide film with an etching gas, the surface of the oxide film is modified with a modifying gas. A selective etching protective film is formed on the surface of the non-oxide film on the surface of the oxide film modified with the aforementioned reforming gas, The surface of the non-oxide film is protected from the etching gas by the etching protective film, while the surface of the oxide film modified with the modified gas is etched with the etching gas. A substrate processing method having the following characteristics.

2. The reformed gas contains boron and reforms the surface of the oxide film into a boron oxide film. The etching protective film contains a desired element X, The substrate processing method according to claim 1, wherein forming the etching protective film includes supplying a raw material gas containing the element X and a reaction gas that reacts with adsorbed substances of the raw material gas to the substrate.

3. The reformed gas is BCl ３ , BBr ３ , BI ３ , B(CH ３ ) ３ , B ２ H ６ , BF ３ , C ９ H ２４ BN ３ , C ３ H ９ B, C ６ H １５ B, and B ３ N ３ H ６ The substrate processing method according to claim 2, comprising at least one of them.

4. The substrate processing method according to claim 2, wherein the raw material gas contains a compound of element X and a halogen.

5. The etching gas is He, Ne, Ar, Kr, Xe, H ２ , O ２ COS, NH ３ SO ２ CO ２ CO, CH ４ NO ２ NO, N ２ , Cl ２ F ２ HF, XeF ２ , CLF ３ , BrF ３ HCl, Br ２ HBr, I ２ , HI, NF ３ , SOCl ２ SO ２ Cl ２ SF ６ CF ４ ,CH ３ F, CHF ３ , C ４ F ６ , C ４ F ８ ,CH ３ Cl, COCl ２ , and CH ３ The substrate processing method according to claim 2, comprising at least one Br.

6. The substrate processing method according to claim 5, wherein the etching gas is plasma-generated.

7. The reformed gas contains halogens without substantially containing carbon, and adsorbs halogens onto the surface of the oxide film. The substrate processing method according to claim 1, wherein forming the etching protective film includes supplying a raw material gas and a reaction gas that reacts with adsorbed substances of the raw material gas to the substrate.

8. The reformed gas is Cl ２ F ２ HF, XeF ２ , CLF ３ , BrF ３ HCl, Br ２ HBr, I ２ , HI, NF ３ , SOCl ２ SO ２ Cl ２ , and SF ６ A substrate processing method according to claim 7, comprising at least one of the following.

9. The reformed gas contains a compound of carbon and halogen, and adsorbs halogen onto the surface of the oxide film. The substrate processing method according to claim 1, wherein forming the etching protective film includes supplying a raw material gas and a reaction gas that reacts with adsorbed substances of the raw material gas to the substrate.

10. The reformed gas is CF ４ ,CH ３ F, CHF ３ , C ４ F ６ , C ４ F ８ ,CH ３ Cl, COCl ２ , and CH ３ The substrate processing method according to claim 9, comprising at least one Br.

11. The substrate processing method according to claim 1, wherein the oxide film comprises a compound of a metal and oxygen or a compound of a semiconductor element and oxygen.

12. The substrate processing method according to claim 1, wherein the non-oxide film has an oxygen content of 0 at% to 10 at%.

13. The etching gas is He, Ne, Ar, Kr, Xe, H ２ , O ２ COS, NH ３ SO ２ CO ２ CO, CH ４ NO ２ NO, N ２ , Al(CH ３ ) ２ Cl, Al(CH ３ ) ３ SiCl ４ TiCl ４ , or Sn(CH ３ COCHCOCH ３ ) ２ A substrate processing method according to claim 7 or 9, comprising at least one of the above.

14. The substrate processing method according to claim 13, wherein the etching gas is plasma-generated.

15. The substrate processing method according to claim 1, wherein the first cycle, which includes supplying the modified gas and forming the etching protective film, is repeated multiple times.

16. The substrate processing method according to claim 1, wherein the second cycle, which includes supplying the modified gas, forming the etching protective film, and supplying the etching gas, is repeated multiple times.

17. The substrate processing method according to claim 1, wherein, after supplying the modified gas, forming the etching protective film, and supplying the etching gas, the supply of the modified gas and the supply of the etching gas are performed once or more times without intervening the formation of the etching protective film.

18. The substrate processing method according to claim 17, comprising supplying the modified gas, forming the etching protective film, and supplying the etching gas, and thereafter repeatedly performing a third cycle multiple times, which includes supplying the modified gas and supplying the etching gas once or more times without intervening the formation of the etching protective film.

19. A processing container for housing the aforementioned substrate, The processing container includes a holding section for holding the substrate inside, A supply unit that supplies gas to the substrate held in the holding unit, A control unit that controls the supply unit, Equipped with, The control unit performs control to carry out the substrate processing method described in any one of claims 1 to 12 and 15 to 18, wherein the control unit is a substrate processing apparatus.

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