Substrate processing method and plasma processing device

Abstract

Provided is a substrate processing method comprising: (A) preparing a substrate; (B) forming a metal-containing film on the surface of the substrate, the metal-containing film including a first ligand and a second ligand which have different thermal reactivities with oxygen; (C) heat-treating the metal-containing film; (D) irradiating the metal-containing film in a prescribed pattern with extreme ultraviolet rays, and forming, on the metal-containing film, an exposed part irradiated with the extreme ultraviolet rays and an unexposed part not irradiated with the extreme ultraviolet rays.

Description

Substrate processing method and plasma processing apparatus

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

[0002] Patent Document 1 discloses a method in which a metal oxide-based EUV photoresist is deposited on a substrate, the substrate is then subjected to a heat treatment called a post-apply bake (PAB), and the resist is then exposed to EUV light to pattern the resist, thereby forming exposed and unexposed regions, and the substrate is then subjected to a heat treatment called a post-exposure bake (PEB), after which the unexposed regions are selectively removed.

[0003] Patent Literature 2 discloses a photoresist-less method for forming a metal hard mask, which includes depositing an EUV-sensitive metal-containing film on a semiconductor substrate, and then patterning the metal-containing film by directly exposing it to EUV in a vacuum environment to form a metal hard mask.

[0004] Patent Document 3 discloses a method for forming a metal oxide-containing hard mask, which includes depositing an EUV-sensitive metal oxide-containing film on a semiconductor substrate by a vapor deposition process, then exposing a portion of the metal oxide-containing film to EUV to form a pattern in the metal oxide-containing film, and then developing the pattern in the metal oxide-containing film to remove one of the exposed and unexposed portions to form a metal oxide-containing hard mask.

[0005] JP-T-2022-538555 A JP-A-2015-201622 JP-A-2017-116923

[0006] The present disclosure provides a substrate processing method and a plasma processing apparatus for forming a metal-containing film that can achieve both stability of the resist film and high sensitivity.

[0007] According to one aspect of the present disclosure, there is provided a substrate processing method including: (A) preparing a substrate; (B) forming a metal-containing film on a surface of the substrate, the metal-containing film including a first ligand and a second ligand having different thermal reactivities with oxygen; (C) heat-treating the metal-containing film; and (D) irradiating the metal-containing film with extreme ultraviolet light in a predetermined pattern to form, in the metal-containing film, exposed portions irradiated with the extreme ultraviolet light and unexposed portions not irradiated with the extreme ultraviolet light.

[0008] According to one aspect, it is possible to form a metal-containing film that can achieve both stability and high sensitivity of the resist film.

[0009] 1 is a schematic cross-sectional view showing an example of a plasma processing apparatus; an example of a film structure in a metal-containing resist film formation step of a reference example; a flowchart showing an example of a method for forming a metal-containing resist film according to the first embodiment; a diagram showing an example of a film cross section in each step of forming a film according to the first embodiment; a diagram showing an example of a film cross section in each step of forming a film according to the first embodiment; a diagram showing an example of a film cross section in each step of forming a film according to the first embodiment; a diagram showing an example of a film cross section in each step of forming a film according to the first embodiment; a diagram showing an example of a film cross section in each step of forming a film according to the first embodiment; a diagram showing an example of a film cross section in each step of forming a film according to the first embodiment; a diagram showing an example of a film structure in each step of forming a film according to the first embodiment; a diagram showing an example of an experiment result on the temperature dependence of the solubility of a metal-containing film; a diagram showing an example of an experiment result on the sensitivity of a metal-containing film; a flowchart showing an example of a method for forming a metal-containing resist film according to the second embodiment; a diagram showing an example of a film cross section in each step of forming a film according to the second embodiment; a diagram showing an example of a film cross section in each step of forming a film according to the second embodiment; a diagram showing an example of a film cross section in each step of forming a film according to the second embodiment; a diagram showing an example of a film cross section in each step of forming a film according to the second embodiment; a diagram showing an example of a film cross section in each step of forming a film according to the second embodiment; a diagram showing an example of a film cross section in each step of forming a film according to the second embodiment; a diagram showing an example of a film cross section in each step of forming a film according to the second embodiment; 10A to 10C show examples of film structures in each step of forming a film according to the second embodiment.

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals, and redundant explanations may be omitted.

[0011] [Plasma Processing Apparatus] An example of a plasma processing apparatus 1 will be described with reference to Fig. 1. Fig. 1 is a schematic cross-sectional view showing the example of the plasma processing apparatus 1. The plasma processing apparatus 1 is an example of an apparatus that forms a metal-containing film on a substrate W such as a semiconductor wafer by a chemical vapor deposition (CVD) method using plasma.

[0012] The plasma processing apparatus 1 includes a substantially cylindrical airtight processing chamber 2. An exhaust chamber 21 is provided in the center of the bottom wall of the processing chamber 2.

[0013] The exhaust chamber 21 has, for example, a substantially cylindrical shape that protrudes downward. An exhaust flow path 22 is connected to the exhaust chamber 21, for example, at a side surface of the exhaust chamber 21.

[0014] An exhaust unit 24 is connected to the exhaust flow path 22 via a pressure adjustment unit 23. The pressure adjustment unit 23 includes a pressure adjustment valve such as a butterfly valve. The exhaust flow path 22 is configured so that the pressure inside the processing vessel 2 can be reduced by the exhaust unit 24. A transfer port 25 is provided on the side of the processing vessel 2. The transfer port 25 is configured to be freely opened and closed by a gate valve 26. The substrate W is loaded and unloaded between the processing vessel 2 and a transfer chamber (not shown) via the transfer port 25.

[0015] A mounting table 3 for holding a substrate W substantially horizontally is provided within the processing chamber 2. The mounting table 3 is substantially circular in plan view and supported by a support member 31. A substantially circular recess 32 for mounting a substrate W having a diameter of, for example, 300 mm is formed in the surface of the mounting table 3. The recess 32 has an inner diameter slightly larger (for example, about 1 mm to 4 mm) than the diameter of the substrate W. The depth of the recess 32 is configured to be substantially the same as the thickness of the substrate W. The mounting table 3 is made of a ceramic material such as aluminum nitride (AlN). Alternatively, the mounting table 3 may be made of a metal material such as nickel (Ni). Note that instead of the recess 32, a guide ring for guiding the substrate W may be provided around the periphery of the surface of the mounting table 3.

[0016] A grounded lower electrode 33, for example, is embedded in the mounting table 3. A temperature adjustment mechanism 34 is embedded below the lower electrode 33. The temperature adjustment mechanism 34 adjusts the mounting table 3 or the substrate W placed thereon to a set temperature based on a control signal from the control unit 9. If the mounting table 3 is made entirely of metal, the entire mounting table 3 functions as the lower electrode, so the lower electrode 33 does not need to be embedded in the mounting table 3. The mounting table 3 is provided with a plurality of (for example, three) lifting pins 41 for holding and lifting up and down the substrate W placed on the mounting table 3. The lifting pins 41 are made of a material such as alumina (Al ２ O ３ The lift pins 41 may be made of ceramics such as quartz or the like. The lower ends of the lift pins 41 are attached to a support plate 42. The support plate 42 is connected to a lift mechanism 44 provided outside the processing vessel 2 via a lift shaft 43.

[0017] The lifting mechanism 44 is installed, for example, at the bottom of the exhaust chamber 21. The bellows 45 is provided between the lifting mechanism 44 and an opening 211 for the lifting shaft 43 formed in the bottom surface of the exhaust chamber 21. The support plate 42 may be shaped so that it can be raised and lowered without interfering with the support member 31 of the mounting table 3. The lifting pins 41 are configured to be able to be raised and lowered between the upper side and the lower side of the surface of the mounting table 3 by the lifting mechanism 44. In other words, the lifting pins 41 are configured to be able to protrude from the top surface of the mounting table 3.

[0018] An upper electrode (gas supply unit 5) is provided on the ceiling wall 27 of the processing vessel 2 via an insulating member 28. The gas supply unit 5 forms the upper electrode and faces the lower electrode 33. An RF power supply 51 is connected to the gas supply unit 5 via a matching box 511. The frequency band of the RF power supply 51 is, for example, 450 kHz to 2.45 GHz. By supplying RF power from the RF power supply 51 to the upper electrode (gas supply unit 5), an RF electric field is generated between the upper electrode (gas supply unit 5) and the lower electrode 33. The gas supply unit 5 includes a hollow gas diffusion chamber 52. A number of holes 53 are arranged, for example, evenly, on the bottom surface of the gas diffusion chamber 52 for dispersing and supplying the processing gas into the processing vessel 2. A heating mechanism 54 is embedded in the gas supply unit 5, for example, above the gas diffusion chamber 52. The heating mechanism 54 is heated to a set temperature by receiving power from a power supply unit (not shown) based on a control signal from the control unit 9.

[0019] A gas supply path 6 is provided in the gas diffusion chamber 52. The gas supply path 6 is in communication with the gas diffusion chamber 52. A gas source 61 is connected to the upstream side of the gas supply path 6 via a gas line 62. The gas source 61 includes, for example, various processing gas supply sources, mass flow controllers, and valves (none of which are shown). The processing gas includes gases used in the substrate processing method described below. The processing gas is introduced from the gas source 61 into the gas diffusion chamber 52 via the gas line 62.

[0020] The process gas may be a first process gas containing a metal-containing precursor gas, which is used to form the metal-containing film 102 (see FIGS. 4B and 9B ) in step S11 (see FIG. 3 ) and step S21 (see FIG. 8 ), which will be described later.

[0021] The plasma processing apparatus 1 includes a control unit 9. The control unit 9 is, for example, a computer and includes a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), an auxiliary storage device, etc. The CPU operates based on a program stored in the ROM or the auxiliary storage device, and controls the operation of the plasma processing apparatus 1. The control unit 9 may be provided inside or outside the plasma processing apparatus 1. If the control unit 9 is provided outside the plasma processing apparatus 1, the control unit 9 can control the plasma processing apparatus 1 via communication means such as wired or wireless.

[0022] Although the plasma processing apparatus 1 has been described as a plasma processing apparatus that generates capacitively coupled plasma (CCP), the present invention is not limited to this. It may also be a plasma processing apparatus that generates remote plasma using high frequency (RF, VHF) or microwave (MW). The plasma processing apparatus that generates remote plasma may be a plasma processing apparatus that generates remote plasma within a processing vessel that accommodates a substrate W, or a plasma processing apparatus that supplies the generated remote plasma into the processing vessel that accommodates a substrate W.

[0023] [Method of forming a resist film according to a reference example] A method of forming a metal-containing resist film according to a reference example will be described with reference to Fig. 2. A method of forming a Sn (tin) oxide resist film as an example of a metal-containing resist film will be described below. Fig. 2 shows an example of a film structure in a process of forming a metal-containing resist film according to a reference example. Fig. 2 shows the film structure on the substrate W in each process, with the substrate W divided into an exposed portion and an unexposed portion. The upper part of Fig. 2 shows the film structure of the exposed portion, and the lower part shows the film structure of the unexposed portion.

[0024] First, a metal-containing precursor gas is supplied to the processing chamber 2. As shown in (1-1) and (2-1) of FIG. 2, the supplied metal-containing precursor gas contains, for example, metal Sn, an alkoxy group L, and a ligand R ３ The alkoxy group L has the formula O—C ｍ H ｎThe ligand R contains a bond, O is an oxygen atom, m is an integer of 0 or 1 or more, and n is an integer of 1 or more. ３ is a substance derived from a precursor contained in the metal-containing precursor gas, and M-C ａ H ｂ M is a metal (Sn), and a and b are integers of 1 or more.

[0025] The plasma processing apparatus 1 forms a metal-containing film using a CVD method. During this process, plasma is generated from a metal-containing precursor gas, and a metal-containing oligomer is deposited on the surface of the substrate W by a plasma polymerization reaction. As a result, a metal-containing film containing the metal-containing oligomer is formed on the surface of the substrate W, as shown in (1-2) and (2-2) in Figure 2. Note that an oligomer refers to a polymer (multimer) formed by the bonding of a relatively small number of monomers (for example, up to a dozen molecules).

[0026] Next, the substrate W on which the metal-containing film has been formed is subjected to an EUV (Extreme Ultraviolet) exposure process. In the exposure process, for example, the metal-containing film is irradiated with EUV through a photomask having a predetermined pattern under vacuum, to form an exposed portion irradiated with EUV and an unexposed portion not irradiated with EUV. As a result, in the exposed portion, the ligand R in the metal-containing film is oxidized, as shown in (1-3) of FIG. ３ is released and converted into an OH group, and the ligand R ３ The unexposed areas, on the other hand, remain soluble.

[0027] Next, the exposed and unexposed areas are heated by a heat treatment (Post Exposure Bake: PEB). In the exposed areas, the heat promotes a condensation reaction between OH groups, and the metal-containing film solidifies to form an insoluble Sn oxide resist film, as shown in FIG. 2 (1-4). On the other hand, in the unexposed areas, the ligand R ３ Therefore, as shown in FIG. 2 (2-3), in the unexposed area, the ligand R ３The condensation reaction is suppressed by the above reaction, and the metal-containing film does not solidify but remains soluble. In the development process, the negative resist film is processed, and the unexposed areas with the soluble metal-containing film are removed by a wet or dry process, leaving the exposed areas with the insoluble metal-containing film. This results in the formation of a metal-containing film (Sn oxide resist film) with a predetermined pattern.

[0028] The sensitivity of the Sn oxide resist film is determined by the Sn and ligand R ３ For example, the oligomer shown in Figure 2 (1-2) has a binding energy with the ligand R ３ is terminated by the ligand R as shown in (1-3) by exposure treatment (EUV). ３ In order to sufficiently remove Sn, a large amount of exposure is required. ３ This indicates that the binding energy with the metal-containing film is high and the sensitivity of the metal-containing film is low.

[0029] In other words, Sn and the ligand R ３ The lower the bond energy between the Sn—R bond and the metal-containing resist film, the higher the sensitivity of the metal-containing resist film. Therefore, from the viewpoint of high sensitivity, a film structure with a low Sn—R bond energy is desirable. On the other hand, a film with a low Sn—R bond energy increases instability. For this reason, it is difficult to achieve both film stability and high sensitivity with the resist film forming method of the reference example.

[0030] Therefore, in the film formation methods according to the first and second embodiments described below, a substrate processing method is provided in which a metal-containing resist film (Sn oxide resist film) that can achieve both film stability and high sensitivity by forming a metal-containing oligomer containing two types of ligands.

[0031] First Embodiment [Method of Forming Resist Film] A substrate processing method for forming a metal-containing resist film according to the first embodiment will be described with reference to FIGS. 3 to 5. FIG. 3 is a flowchart showing an example of a substrate processing method for forming a metal-containing resist film according to the first embodiment. FIGS. 4A to 4F are views showing an example of a film cross section in each step of forming a film according to the first embodiment. FIG. 5 is a view showing an example of a film structure in each step of forming a film according to the first embodiment. FIG. 5 shows the film structure on the substrate W in each step, with the substrate W divided into an exposed portion and an unexposed portion. The upper part of FIG. 5 shows the film structure of the exposed portion, and the lower part shows the film structure of the unexposed portion. In addition, a substrate processing method for forming a Sn oxide resist film as an example of a metal-containing resist film will be described below.

[0032] (Step S10) In step S10, a substrate W is prepared in the processing chamber 2. As shown in FIG. 4A , the prepared substrate W has an undercoat film 101. The control unit 9 controls a transfer device (not shown) to transfer the substrate W having the undercoat film 101 to the processing chamber 2 of the plasma processing apparatus 1 and place it in the recess 32 of the mounting table 3.

[0033] (Step S11) In step S11, a ligand R having a thermal reactivity different from that of oxygen is ３ and ligand R １ A first process gas having a metal-containing precursor gas containing:

[0034] The alkoxy group L is O—C ｍ H ｎ It contains a bond, O is an oxygen atom, m is 0 or an integer of 1 or more, and n is an integer of 1 or more.

[0035] Ligand R ３ is a substance derived from a precursor contained in the metal-containing precursor gas, and M-C ａ H ｂ M is a metal, and a and b are integers of 1 or more.

[0036] Ligand R １is a substance derived from a precursor contained in the metal-containing precursor gas, and M-C ｘ H ｙ M is a metal, x is smaller than a, x is an integer of 0 or 1 or more, and y is an integer of 1 or more.

[0037] M may be one selected from Sn, Sb, In, Al, Ti, Mn, Ta, Hf, W, Te, Bi.

[0038] The metal-containing precursor gas is M-C ａ H ｂ a first precursor having a bond, and M-C ｘ H ｙ The metal-containing precursor gas may include, but is not limited to, a plurality of precursors, such as M-C ａ H ｂ Bonding and M-C ｘ H ｙ The compound may include one precursor having a bond.

[0039] As shown in (1-1) and (2-1) of FIG. 5, the metal-containing precursor gas is M-C ａ H ｂ a first precursor having a bond, and M-C ｘ H ｙ and a second precursor having a bond, wherein the first precursor has two alkoxy groups L and two ligands R ３ In the second precursor, Sn is bound to four ligands R １ However, in the second precursor, Sn is bonded to at least one ligand R １ The remaining bonds with Sn are made by the ligand R １ It doesn't have to be.

[0040] Ligand R １ has a first thermal reactivity, and the ligand R ３ has a second thermal reactivity that is lower than the first thermal reactivity. １ is the ligand R ３ The reaction occurs at a lower heating temperature than that of the ligand R ３ has a first photoreactivity and a ligand R １has a second photoreactivity that is lower than the first photoreactivity. ３ is the ligand R １ reacts with less exposure than

[0041] Ligand R １ is an example of a second ligand having a first thermal reactivity. ３ is an example of a first ligand having a second thermal reactivity that is lower than the first thermal reactivity.

[0042] Here, the control unit 9 controls the gas source 61 to supply a first process gas having a metal-containing precursor gas from the gas supply unit 5 into the process vessel 2 through the multiple holes 53. The control unit 9 also controls the RF power supply 51 to supply RF power to the upper electrode (gas supply unit 5). As a result, plasma is generated from the first process gas in the process vessel 2, and the substrate W is exposed to the generated plasma.

[0043] (Step S12) In step S12, a polymerization reaction of the generated plasma forms a metal-containing film 102 on the surface of the substrate W (see FIG. 4B). １ and ligand R ３ 5 (1-2) and (2-2), the metal-containing film 102 is formed by depositing metal-containing oligomers containing a metal (M), oxygen (O), carbon (C), and hydrogen (H). Here, the metal (M) is one selected from Sn, Sb, In, Al, Ti, Mn, Ta, Hf, W, Te, and Bi. This results in the formation of a metal-containing film 102 containing two types of ligands with different thermal reactivities.

[0044] Specifically, the metal-containing precursor gas is, for example, Sn(OC ４ H ９ ) ４ , Sn(OC ４ H ９ ) ２ (CH ３ ) ２ , Sn(OC ４ H ９ ) ２ (C ２ H ５ ) ２ , Sn(OC４ H ９ ) ２ (C ３ H ８ ) ２ 、Sn(OC ４ H ９ ) ２ (C ４ H ９ ) ２ 、Sn(OC ４ H ９ ) ３ (CH ３ ) １ 、Sn(OC ４ H ９ ) ３ 、(C ２ H ５ ) １ 、Sn(OC ４ H ９ ) ３ (C ３ H ８ ) １ 、Sn(OC ４ H ９ ) ３ (C ４ H ９ ) １ 、Sn(CH ３ ) ４ 、SnH(CH ３ )<​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​The two precursor gases selected may be Sn—C ａ H ｂ Bonding and Sn-C ｘ H ｙ It has a bond relationship.

[0045] The first process gas may include an additive gas and / or an inert gas. The additive gas may be H ２ , C.H. ４ , C ２ H ２ , C ２ H ４ , C ３ H ６ The additive gas is at least one gas selected from the group consisting of M-C ａ H ｂ and M.-C. ｘ H ｙ It is possible to form bonds. From the viewpoint of stability and cost, it is not always possible to use a material having the desired M-CaHb bond and M-CxHy bond as a metal-containing precursor gas. Therefore, by adding an additive gas and controlling the concentration, it is possible to impart the desired M-CaHb bond and M-CxHy bond and concentration. This makes it possible to include the desired bond in the film without being restricted by the metal-containing precursor gas. This also improves the degree of freedom in selecting thermal reactivity and photoreactivity. The material is an inert gas, and can be selected from He, Ar, Ne, Xr, N ２ At least one gas selected from:

[0046] An example of a recipe for the process of forming metal-containing film 102 is shown below.

[0047] Plasma type: CCP, 13.56 MHz, 10 W to 500 W Substrate temperature: -10°C or higher and 310°C or lower Pressure inside processing chamber: 100 mTorr (13.3 Pa) to 20 Torr (26.7 Pa) Next, the control unit 9 controls a transfer device (not shown) to transfer the substrate W out of the processing chamber 2 of the plasma processing apparatus 1. Note that the processes from step S10 to step S12 are performed inside the processing chamber 2 in a reduced pressure atmosphere.

[0048] (Step S13) In step S13, a heat treatment (Post Deposition Bake: PDB) is performed on the metal-containing film 102 (see FIG. 4C). Specifically, the metal-containing film 102 is reacted with oxygen or water at a predetermined temperature to form ligands R １ is eliminated and converted into an OH group, forming a Sn—OH bond, and the ligand R １ As a result, the metal-containing film 102A on the surface of the substrate W is freed from the ligand R １ Ligand R ３ This results in a membrane structure that leaves some of the

[0049] 6 is a diagram showing an example of experimental results of the temperature dependence of the solubility of the metal-containing film 102. The horizontal axis of FIG. 6 represents the temperature of the substrate W, and the vertical axis represents the thickness of the remaining film of the metal-containing film 102. The remaining film thickness increases as the metal-containing film 102 solidifies. The solidification of the metal-containing film 102 is promoted as the ligand R is desorbed and converted to an OH group and removed. The line RA represents the distance between the surface of the metal-containing film 102 and the surface of the substrate W where the ligand R is dissolved. １ The line RB shows the temperature dependence of the solubility of metal-containing films terminated with Sn oxide and the ligand R ３ The graph shows the temperature dependence of the solubility of a metal-containing film terminated with the ligand R. １ The metal-containing film terminated with the ligand R was changed to an insoluble film when the substrate W was controlled to 120° C. or higher. ３ The metal-containing film terminated by remained soluble when the substrate W was controlled to a temperature of 120° C. or higher but lower than 250° C., but changed to an insoluble film when the mounting table 3 was controlled to a temperature of 250° C. or higher.

[0050] Therefore, in step S13, the temperature of the substrate W is controlled to be 120° C. or higher and lower than 250° C., thereby preventing the ligand R １ is removed by detachment, and the ligand R ３ As a result, the metal-containing film 102A can be formed from the metal-containing oligomer with the ligand R ３This suppresses solidification of the metal-containing film 102A. In this way, as shown in (1-3) and (2-3) in Figure 5, after the heat treatment (PDB), a metal-containing oligomer can be formed in which the ligand R3 and an OH group coexist. This allows the formation of a metal-containing film 102A (metal-containing resist film) that has high photoreactivity (sensitivity) and excellent film stability in the subsequent exposure process.

[0051] (Step S14) In step S14, substrate W having metal-containing film 102A formed on underlayer film 101 is subjected to an exposure process (EUV). Here, metal-containing film 102A is irradiated with EUV under vacuum through photomask 103 having a predetermined pattern, as shown in FIG. 4D , to form exposed portion A irradiated with EUV and unexposed portion B not irradiated with EUV.

[0052] As a result, in the exposed area A, the highly photoreactive ligand R ３ The bond between Sn and Sn is broken and reacts with oxygen or water to form a Sn-OH bond, and the ligand R ３ is eliminated and converted into an OH group. In addition, a condensation reaction between the OH groups progresses. As a result, as shown in (1-4) of FIG. 5, the ligand R ３ is removed, and metal-containing film 102A1 of metal-containing oligomer having Sn—OH bonds is formed. Unexposed portion B has not been irradiated with EUV and therefore has the film structure of metal-containing film 102A.

[0053] (Step S15) In step S15, the substrate W that has been subjected to the exposure process (EUV) is subjected to a heat treatment (Post Exposure Bake: PEB). Here, the heat treatment promotes the condensation reaction of the metal-containing oligomer in the exposed portion A.

[0054] That is, by promoting the condensation reaction between Sn—OH bonds in the film in the exposed portion A, the film is solidified, and an insoluble metal-containing resist film 102A2 is formed as shown in Fig. 4E. Fig. 5 (1-5) shows that the condensation reaction of the metal-containing oligomer in the exposed portion A is promoted by the heat treatment (PEB), and an insoluble metal-containing resist film 102A2 (Sn oxide resist film) having Sn—O bonds is formed.

[0055] On the other hand, in the unexposed area B, the ligand R in the metal-containing film 102A ３ This suppresses the condensation reaction of the metal-containing oligomer, maintains solubility, and provides development properties, thereby making the metal-containing film 102A in the unexposed area B a film that can be removed by the development process in the next step.

[0056] (Step S16) In step S16, the substrate W is subjected to a development process. Here, the development process selectively removes the unexposed portion B (see FIG. 4F). The development process can be at least one of a wet process and a dry process.

[0057] When the development treatment is a wet process, the substrate W is exposed to an organic solvent to selectively remove the unexposed portion B. The organic solvent may be, for example, alcohol.

[0058] When the development process is a dry process, the substrate W is exposed to a halogen-containing gas to increase the etching rate of the unexposed portion B, thereby selectively removing the unexposed portion B. The halogen-containing gas may be HBr, HCl, BCl, or the like. ３ At least one of the above can be used.

[0059] As described above, according to the film formation method of the first embodiment, it is possible to form the metal-containing resist film 102A2 on the base film 101. The metal-containing film 102 formed in the plasma processing apparatus 1 can be a negative resist film that allows the unexposed portion B to be selectively removed.

[0060] In addition, two types of ligands R with different thermal reactivity １ , R ３ and forming a metal-containing film having the ligand R １ The ligand R is eliminated and converted into an OH group. ３ The condensation reaction of the OH groups is then accelerated by heat treatment (PEB), thereby forming a metal-containing resist film with high sensitivity and excellent stability.

[0061] 7 is a diagram showing an example of experimental results regarding the sensitivity of a metal-containing film. The horizontal axis of FIG. 7 indicates exposure time, and the vertical axis indicates residual film thickness (residual film thickness). The reference example shown by the dashed line in FIG. 7 is a reference example in which one type of ligand R shown in (1-2) of FIG. 2 is used. ３ 1 shows the relationship between the exposure time and the remaining film thickness when a metal-containing film having the above structure is subjected to an exposure process (EUV).

[0062] The embodiment shown by the solid line in FIG. 7 is a combination of two types of ligands R １ , R ３ The metal-containing film having the ligand R １ 1 shows the relationship between the exposure time and the remaining film thickness when an exposure process (EUV) is performed after removing the film.

[0063] The longer the exposure time, the larger the exposure dose. In the experiment of FIG. 7, the residual film thickness of the embodiment increased more rapidly with a smaller exposure dose than that of the reference example. The timing at which the residual film thickness increases more rapidly indicates that the metal-containing film switches from soluble to insoluble. In other words, the earlier the timing at which the residual film thickness increases more rapidly, the more the ligand R in the metal-containing film is dissolved with a smaller exposure dose. ３ indicates that has been removed.

[0064] In the reference example, all the ligands R ３ In contrast, in the embodiment, the timing at which the residual film thickness increases sharply is earlier than in the reference example, and therefore, the ligand R in the film is irradiated with light with a smaller exposure amount than in the reference example. ３ In other words, in the embodiment, a metal-containing resist film with higher sensitivity than the reference example was obtained. １ had been previously desorbed and removed from the metal-containing film by heat treatment (PDB), an insoluble metal-containing resist film was obtained with a lower exposure dose than in the Reference Example.

[0065] Second Embodiment [Method of Forming Resist Film] Next, a substrate processing method for forming a metal-containing resist film according to a second embodiment will be described with reference to FIGS. 8 to 10. FIG. 8 is a flowchart illustrating an example of a substrate processing method for forming a metal-containing resist film according to the second embodiment. FIGS. 9A to 9E are diagrams illustrating an example of a film cross section in each step of forming a film according to the second embodiment. FIG. 10 is a diagram illustrating an example of a film structure in each step of forming a film according to the second embodiment. FIG. 10 shows the film structure on the substrate W in each step, with the substrate W divided into an exposed portion and an unexposed portion. The upper part of FIG. 10 shows the film structure of the exposed portion, and the lower part shows the film structure of the unexposed portion. Furthermore, a substrate processing method for forming a Sn oxide resist film as an example of a metal-containing resist film will be described below.

[0066] (Step S20) In step S20, a substrate W is prepared in the processing chamber 2. As shown in Fig. 9A, the prepared substrate W has an undercoat film 101.

[0067] (Step S21) In step S21, a ligand R having a thermal reactivity different from that of oxygen is ３ and ligand R １ A first process gas having a metal-containing precursor gas containing the compound (III) is supplied to the process chamber (2). The metal-containing precursor gas may be an organometallic precursor gas containing oxygen. The organometallic precursor gas containing oxygen may contain an alkoxy group (L).

[0068] As shown in (1-1) and (2-1) of FIG. 10, the metal-containing precursor gas is M-C ａ H ｂ a first precursor having a bond, and M-C ｘ H ｙ and a second precursor having a bond, wherein the first precursor has two alkoxy groups L and two ligands R ３ In the second precursor, Sn is bound to four ligands R １ However, in the second precursor, Sn is bonded to at least one ligand R １ The remaining bonds with Sn are made by the ligand R １ It doesn't have to be.

[0069] The metal-containing precursor gas and the composition of the first process gas containing the metal-containing precursor gas are similar to those of the first process gas used in the first embodiment, and therefore, a description thereof will be omitted here.

[0070] (Step S22) In step S22, a polymerization reaction of the generated plasma forms a metal-containing film 102 on the surface of the substrate W (see FIG. 9B). １ and ligand R ３ As shown in (1-2) and (2-2) of Figure 10, the metal-containing film 102 is formed by depositing metal-containing oligomers containing a metal (M), oxygen (O), carbon (C), and hydrogen (H). Here, the metal (M) is one selected from Sn, Sb, In, Al, Ti, Mn, Ta, Hf, W, Te, and Bi. This results in the formation of a metal-containing film 102 containing two types of ligands with different thermal reactivities.

[0071] An example of a recipe for the process of forming metal-containing film 102 is shown below.

[0072] Plasma type: CCP, 13.56 MHz, 10 W to 500 W Substrate temperature: -10°C or higher and 310°C or lower Pressure inside processing chamber: 100 mTorr (13.3 Pa) to 20 Torr (26.7 Pa) Note that the processes from step S20 to step S22 are performed inside processing chamber 2 in a reduced pressure atmosphere.

[0073] (Step S23) In step S23, substrate W having metal-containing film 102 formed on underlayer film 101 is subjected to an exposure process (EUV). Here, metal-containing film 102 is irradiated with EUV under vacuum through photomask 103 having a predetermined pattern, as shown in FIG. 9C , to form exposed portion A irradiated with EUV and unexposed portion B not irradiated with EUV.

[0074] As a result, in the exposed area A, the highly photoreactive ligand R ３ The bond between Sn and Sn is broken and reacts with oxygen or water to form a Sn-OH bond, and the ligand R ３is eliminated and converted into an OH group. In addition, a condensation reaction between the OH groups progresses. As a result, as shown in (1-3) of FIG. 10, the ligand R ３ is removed and the ligand R １ and a Sn—OH bond is formed (see FIG. 9C). The unexposed portion B is not irradiated with EUV light, and therefore has the film structure of the metal-containing film 102.

[0075] In the exposure process, the ligand R １ Although it is possible that a part of the ligand R １ A portion of the metal-containing film 102B1 remains in the metal-containing film 102B1.

[0076] (Step S24) In step S24, the substrate W that has been subjected to the exposure process (EUV) is subjected to a heat treatment (Post Exposure Bake: PEB). １ The bond between Sn and Sn is broken and reacts with oxygen or water to form a Sn-OH bond, and the ligand R １ is eliminated and converted into an OH group. １ In response to the elimination of the metal, the condensation reaction of the metal-containing oligomer in the exposed area A is promoted.

[0077] That is, by promoting the condensation reaction between Sn—OH bonds in the film in the exposed area A, the film is solidified, and an insoluble metal-containing resist film 102B2 is formed as shown in FIG. 9D. (1-4) in FIG. 10 shows the process of forming the ligand R １ is released and removed, the condensation reaction of the metal-containing oligomer in the exposed area A progresses, and an insoluble metal-containing resist film 102B2 of Sn oxide having Sn—O bonds is formed.

[0078] On the other hand, in the unexposed area B, the highly thermally reactive ligand R １ is released and removed, but as shown in (2-3) of FIG. 10, the ligand R ３ Therefore, in the unexposed area B, the ligand R ３Metal-containing film 102B having ligands R ３ This suppresses the condensation reaction, maintains solubility, and provides development properties, thereby making metal-containing film 102B in unexposed area B a film that can be removed by the development process in the next step.

[0079] (Step S25) In step S25, the substrate W is subjected to a development process. Here, the development process selectively removes the unexposed portion B (see FIG. 9E). The development process can be at least one of a wet process and a dry process.

[0080] When the development treatment is a wet process, the substrate W is exposed to an organic solvent to selectively remove the unexposed portion B. The organic solvent may be, for example, alcohol.

[0081] When the development process is a dry process, the substrate W is exposed to a halogen-containing gas to increase the etching rate of the unexposed portion B and selectively remove the unexposed portion B. The halogen-containing gas may be at least one of HBr and HCl.

[0082] As described above, according to the film formation method of the second embodiment, it is possible to form the metal-containing resist film 102B2 on the base film 101. The metal-containing film 102 formed in the plasma processing apparatus 1 can be a negative resist film that allows the unexposed portion B to be selectively removed.

[0083] In addition, two types of ligands R with different thermal reactivity １ , R ３ and forming a metal-containing film having the ligand R ３ Then, by heat treatment (PEB), the ligand R １ By eliminating the group, converting it to an OH group, and then removing it, the condensation reaction between the OH groups is promoted, thereby making it possible to form a metal-containing resist film that is highly sensitive and excellent in stability.

[0084] In the film formation method according to the first embodiment, a heat treatment (PDB) is performed before the exposure treatment (EUV). Therefore, in the first embodiment, the ligand R １ is first removed by detachment, and then the ligand R is removed by exposure treatment. ３ is removed by detachment.

[0085] In contrast, in the film formation method according to the second embodiment, the heat treatment (PDB) before the exposure treatment is not performed. Therefore, in the second embodiment, the ligand R in the metal-containing film is removed by the exposure treatment (EUV). ３ is first removed by detachment, and then the ligand R is removed by heat treatment (PEB). １ is removed by detachment.

[0086] In this way, in the second embodiment, the ligand R １ Ligand R ３ Ligand R ３ is the ligand R １ Since the number of carbon atoms (C) is greater than that of the ligand R ３ By removing the carbon atoms through desorption, the metal-containing film has a lower carbon content, and a metal-containing film with good exposure characteristics (sensitivity) can be formed.

[0087] [Others] The metal-containing film 102 is reacted with oxygen or water to form Sn—OH bonds, and the ligand R １ or ligand R ３ In the heat treatment (PDB), exposure treatment (EUV), and heat treatment (PEB) that removes H ２ O, O ２ For example, by performing the heat treatment (PDB), the exposure treatment (EUV), and the heat treatment (PEB) in an air atmosphere, the ligand R can be oxidized using water or oxygen components in the air. １ or ligand R ３ Alternatively, the hydrogen or oxygen component contained in the metal-containing film 102 may be used to convert the ligand R １ or ligand R ３ may be eliminated to convert to an OH group.

[0088] Ligand R １ When the number of C atoms in the ligand R is increased from four to five and six, １ The temperature at which metal-containing films with .gtoreq. ...100.degree. C. remain soluble can be increased to as high as 310.degree.

[0089] Thus, the ligand R １ By changing the number of C atoms contained in the substrate W, the temperature of the substrate W can be controlled to be equal to or higher than 120° C. and lower than 310° C. during the heat treatment (PDB). This makes it possible to form a metal-containing film having desired film stability and high sensitivity.

[0090] As described above, the substrate processing method and plasma processing apparatus of this embodiment can form a metal-containing film that can achieve both film stability and high sensitivity.

[0091] The substrate processing method and plasma processing apparatus according to the presently disclosed embodiments should be considered to be illustrative in all respects and not restrictive. The embodiments can be modified and improved in various ways without departing from the spirit and scope of the appended claims. The features described in the above embodiments can be configured in other ways as long as they are not inconsistent, and can be combined as long as they are not inconsistent.

[0092] This international application claims priority based on Japanese Patent Application No. 2023-209601, filed on December 12, 2023, the entire contents of which are incorporated herein by reference.

[0093] REFERENCE SIGNS LIST 1 Plasma processing apparatus 2 Processing chamber 3 Mounting table 5 Gas supply unit 9 Control unit 101 Undercoat film 102 Metal-containing film 102A2 Metal-containing resist film 102B2 Metal-containing resist film A Exposed portion B Unexposed portion W Substrate

Claims

1. A substrate processing method comprising: (A) preparing a substrate; (B) forming a metal-containing film on a surface of the substrate, the metal-containing film including a first ligand and a second ligand having different thermal reactivities with oxygen; (C) heat-treating the metal-containing film; and (D) irradiating the metal-containing film with extreme ultraviolet light in a predetermined pattern to form an exposed portion of the metal-containing film that has been irradiated with the extreme ultraviolet light and an unexposed portion that has not been irradiated with the extreme ultraviolet light.

2. The substrate processing method according to claim 1, wherein the second ligand has a first thermal reactivity, and the first ligand has a second thermal reactivity lower than the first thermal reactivity.

3. The substrate processing method according to claim 2, wherein in (C), the second ligand is removed from the metal-containing film, and then in (D), the first ligand is removed from the exposed area.

4. The substrate processing method according to claim 3, wherein in (C), the second ligand contained in the metal-containing film is converted to an OH group, and then in (D), the first ligand contained in the exposed area is converted to an OH group; and (E) after (D), the metal-containing film is heat-treated to cause a condensation reaction of the OH group.

5. The substrate processing method according to claim 2, wherein in (D), the first ligand is removed from the exposed portion, and then in (C), the second ligand is removed from the metal-containing film.

6. The substrate processing method according to claim 5, wherein in (D), the first ligand contained in the exposed area is converted to an OH group, and then in (C), the second ligand contained in the metal-containing film is converted to an OH group, and the OH group is subjected to a condensation reaction.

7. The substrate processing method according to any one of claims 1 to 6, wherein in (C), a temperature of a mounting table on which the substrate is placed is controlled to a temperature of 120°C or higher and lower than 310°C.

8. The substrate processing method according to claim 7, wherein in (C), a mounting table on which the substrate is placed is controlled to a temperature of 120° C. or higher and lower than 250° C.

9. The substrate processing method according to any one of claims 1 to 6, wherein in (B), a first processing gas having a metal-containing precursor gas containing the first ligand and the second ligand having thermal reactivity different from the oxygen is supplied, plasma of the first processing gas is generated, and a metal-containing film containing the oxygen, the first ligand, and the second ligand is formed on the surface of the substrate by a plasma polymerization reaction.

10. The metal-containing precursor gas is M-C ａ H ｂ Bonding and M-C ｘ H ｙ and a bond, wherein M is a metal, a and b are integers of 1 or more, x is 0 or an integer of 1 or more, and y is an integer of 1 or more.

11. The metal-containing precursor gas is O—C ｍ H ｎ The substrate processing method according to claim 10 , wherein O is an oxygen atom, m is an integer of 0 or 1 or more, and n is an integer of 1 or more.

12. The metal-containing precursor gas is M-C ａ H ｂ A first precursor having a bond, and M-C ｘ H ｙ The method of claim 10 , further comprising:

13. The metal-containing precursor gas is M-C ａ H ｂ Bonding and M-C ｘ H ｙ The method of claim 10 , further comprising one precursor having a bond.

14. The substrate processing method according to claim 10, wherein M is one selected from the group consisting of Sn, Sb, In, Al, Ti, Mn, Ta, Hf, W, Te, and Bi.

15. The substrate processing method according to any one of claims 1 to 6, wherein the inside of a processing vessel in which (D) is carried out is under vacuum.

16. The substrate processing method according to claim 4, wherein in (E), the temperature of the substrate is controlled to be in the range of -10°C to 310°C.

17. The method of claim 9, wherein the first process gas includes an additive gas and / or an inert gas.

18. The additive gas is H ２ , C.H. ４ , C ２ H ２ , C ２ H ４ , C ３ H ６ At least one gas selected from the group consisting of He, Ar, Ne, Xr, and N ２ The method of claim 17 , wherein the gas is at least one selected from the group consisting of:

19. The substrate processing method according to any one of claims 1 to 6, further comprising the step of: (F) selectively removing the unexposed portion from the metal-containing film.

20. A plasma processing apparatus comprising: a processing vessel; a mounting stage for mounting a substrate; a gas supply unit for supplying gas into the processing vessel; a plasma source for supplying power via an upper electrode provided on a ceiling wall of the processing vessel; and a control unit, wherein the control unit controls the following: (A) preparing the substrate on the mounting stage in the processing vessel; and (B) supplying a first processing gas from the gas supply unit, the first processing gas having a metal-containing precursor gas containing a first ligand and a second ligand having different thermal reactivity from oxygen, supplying power from the plasma source via the upper electrode to generate plasma of the first processing gas, and plasma polymerizing the first processing gas to form a metal-containing film containing the oxygen, the first ligand, and the second ligand on a surface of the substrate.

21. A substrate processing method, comprising the steps of: forming a metal-containing film containing said oxygen, said first ligand, and said second ligand on the surface of said substrate, using the plasma processing apparatus according to claim 20.

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