Substrate processing method and plasma processing device

Abstract

To form a metal-containing film that can achieve both resist film stability and high sensitivity.SOLUTION: Provided is a substrate processing method including: (A) preparing a substrate; (B) forming, on the surface of the substrate, a 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 rays in a predetermined pattern, 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.SELECTED DRAWING: Figure 4

Description

Technical Field

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

Background Art

[0002] In Patent Document 1, a metal oxide-based EUV photoresist is deposited on a substrate. Next, after performing a heat treatment called post-application bake (PAB) on the substrate, the resist is exposed to EUV light to pattern the resist, thereby forming an exposed region and an unexposed region. Next, after performing a heat treatment called post-exposure bake (PEB) on the substrate, the unexposed region is selectively removed. A method including these steps is disclosed.

[0003] In Patent Document 2, an EUV-sensitive metal-containing film is deposited on a semiconductor substrate. Next, the metal-containing film is directly exposed to EUV in a vacuum environment to be patterned, thereby forming a metal hard mask. A method for forming a photoresistless metal hard mask including these steps is disclosed.

[0004] In Patent Document 3, an EUV photosensitive metal oxide-containing film is deposited on a semiconductor substrate by vapor deposition. Next, a part of the metal oxide-containing film is exposed to EUV to form a pattern in the metal oxide-containing film. Next, the pattern of the metal oxide-containing film is developed to form a metal oxide-containing hard mask, and one of the exposed portion and the unexposed portion is removed. A method for forming a metal oxide-containing hard mask including these steps is disclosed.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

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

Means for Solving the Problems

[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 containing a first ligand and a second ligand having different thermal reactivity with oxygen on the surface of the substrate; (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 irradiated with the extreme ultraviolet light and an unexposed portion not irradiated with the extreme ultraviolet light in the metal-containing film.

Effects of the Invention

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

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Embodiments for Carrying Out the Invention

[0010] Hereinafter, embodiments for carrying out the present disclosure will be described with reference to the drawings. In each drawing, the same reference numerals are assigned to the same components, and redundant descriptions may be omitted.

[0011] [Plasma Processing Apparatus] An example of the plasma processing apparatus 1 will be described with reference to FIG. 1. FIG. 1 is a schematic cross-sectional view showing an example of the plasma processing apparatus 1. The plasma processing apparatus 1 is an example of an apparatus for forming 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 container 2. An exhaust chamber 21 is provided at the central portion of the bottom wall of the processing container 2.

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

[0014] An exhaust section 24 is connected to the exhaust flow path 22 via a pressure adjustment section 23. The pressure adjustment section 23 includes a pressure adjustment valve such as a butterfly valve. The exhaust flow path 22 is configured such that the inside of the processing container 2 can be depressurized by the exhaust section 24. A transfer port 25 is provided on the side surface of the processing container 2. The transfer port 25 is configured to be openable and closable by a gate valve 26. Loading and unloading of the substrate W between the inside of the processing container 2 and a transfer chamber (not shown) are performed through the transfer port 25.

[0015] A mounting table 3 for holding the substrate W substantially horizontally is provided inside the processing container 2. The mounting table 3 is formed in a substantially circular shape in plan view and is supported by a support member 31. A substantially circular recess 32 for mounting a substrate W with a diameter of, for example, 300 mm is formed on 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, for example. The mounting table 3 is formed of a ceramic material such as aluminum nitride (AlN), for example. Also, the mounting table 3 may be formed of a metal material such as nickel (Ni). Instead of the recess 32, a guide ring for guiding the substrate W may be provided at the peripheral edge of the surface of the mounting table 3.

[0016] For example, a grounded lower electrode 33 is embedded in the mounting table 3. A temperature control mechanism 34 is embedded below the lower electrode 33. The temperature control mechanism 34 adjusts the mounting table 3 or the mounted substrate W to a set temperature based on a control signal from the control unit 9. When the entire mounting table 3 is made of metal, the entire mounting table 3 functions as a lower electrode, so the lower electrode 33 does not need to be embedded in the mounting table 3. A plurality (for example, three) of lifting pins 41 for holding and lifting the substrate W mounted on the mounting table 3 are provided on the mounting table 3. The material of the lifting pins 41 may be, for example, ceramics such as alumina (Al2O3) or quartz. The lower ends of the lifting pins 41 are attached to a support plate 42. The support plate 42 is connected to a lifting mechanism 44 provided outside the processing container 2 via a lifting shaft 43.

[0017] The elevating mechanism 44 is installed, for example, at the lower part of the exhaust chamber 21. The bellows 45 is provided between the opening 211 for the elevating shaft 43 formed on the lower surface of the exhaust chamber 21 and the elevating mechanism 44. The shape of the support plate 42 may be a shape that can be elevated without interfering with the support member 31 of the mounting table 3. The elevating pin 41 is configured to be elevable between the upper side and the lower side of the surface of the mounting table 3 by the elevating mechanism 44. In other words, the elevating pin 41 is configured to be able to protrude from the upper surface of the mounting table 3.

[0018] An upper electrode (gas supply unit 5) is provided on the top wall 27 of the processing container 2 via an insulating member 28. The gas supply unit 5 forms the upper electrode and faces the lower electrode 33. An RF power supply 51 is connected to the gas supply unit 5 via a matcher 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 configured to be 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 for dispersedly supplying the processing gas into the processing container 2 are, for example, evenly arranged on the lower surface of the gas diffusion chamber 52. Above the gas diffusion chamber 52 in the gas supply unit 5, for example, a heating mechanism 54 is embedded. The heating mechanism 54 is heated to a set temperature by being supplied with 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 communicates 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, a supply source of various processing gases, a mass flow controller, and a valve (all not shown). The processing gas includes the gas used in the substrate processing method described later. The processing gas is introduced from the gas source 61 into the gas diffusion chamber 52 via the gas line 62.

[0020] Examples of the processing gas include a first processing gas containing a metal-containing precursor gas. The first processing gas is a processing gas used for forming a metal-containing film 102 (see FIGS. 4(b) and 9(b)) in steps S11 (see FIG. 3) and S21 (see FIG. 8) described below.

[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), a RAM (Random Access Memory), a ROM (Read Only Memory), an auxiliary storage device, and the like. 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 the plasma processing apparatus 1 or outside it. When the control unit 9 is provided outside the plasma processing apparatus 1, the control unit 9 can control the plasma processing apparatus 1 by means of communication means such as wired or wireless communication.

[0022] Although the plasma processing apparatus 1 has been described by taking, as an example, a plasma processing apparatus that generates capacitively coupled plasma (CCP), the present invention is not limited to this. It may be a plasma processing apparatus that generates remote plasma using high frequency (RF, VHF) or microwave (MW). Further, the plasma processing apparatus that generates remote plasma may be a plasma processing apparatus that generates remote plasma inside a processing chamber that houses the substrate W, or may be a plasma processing apparatus that supplies the generated remote plasma into the processing chamber that houses the substrate W.

[0023] [Method for forming a resist film in the reference example] With reference to FIG. 2, a method for forming a metal-containing resist film in the reference example will be described. Hereinafter, a method for forming a tin oxide resist film as an example of the metal-containing resist film will be described. FIG. 2 shows an example of the film structure in the process of forming the metal-containing resist film in the reference example. In FIG. 2, the upper part shows the film structure on the substrate W in the exposed portion, and the lower part shows the film structure on the substrate W in the unexposed portion, dividing the upper surface of the substrate W into an exposed portion and an unexposed portion in each step.

[0024] First, a metal-containing precursor gas is supplied to the processing vessel 2. As shown in (1-1) and (2-1) of FIG. 2, the supplied metal-containing precursor gas has, for example, a metal Sn, an alkoxy group L, and a ligand R3. The alkoxy group L contains an O-C m H n bond, where O is an oxygen atom, m is 0 or an integer of 1 or more, and n is an integer of 1 or more. The ligand R3 is a substance derived from the precursor contained in the metal-containing precursor gas and has an M-C a H b bond. 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 the CVD method. At this time, plasma is generated from the 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, as shown in (1-2) and (2-2) of FIG. 2, a metal-containing film having a metal-containing oligomer is formed on the surface of the substrate W. Here, an oligomer refers to a polymer (multimer) in which a relatively small number (for example, up to a dozen molecules) of monomers are bonded.

[0026] Next, an EUV (Extreme Ultraviolet) exposure process is performed on the substrate W on which the metal-containing film has been formed. In the exposure process, for example, EUV is irradiated onto the metal-containing film through a photomask having a predetermined pattern under vacuum, forming an exposed portion irradiated with EUV and an unexposed portion not irradiated with EUV. As a result, in the exposed portion, as shown in (1-3) of FIG. 2, the ligand R3 in the metal-containing film is desorbed and converted into an OH group, and the ligand R3 is removed from the metal-containing film. On the other hand, the unexposed portion maintains a soluble state.

[0027] Next, by means of heat treatment (Post Exposure Bake: PEB), the exposed areas and the unexposed areas are heated. In the exposed areas, the condensation reaction between OH groups is promoted by heat, and as shown in (1-4) of FIG. 2, the metal-containing film solidifies to form an insoluble tin oxide resist film. On the other hand, in the unexposed areas, the ligand R3 suppresses the condensation reaction between OH groups due to thermal energy. Therefore, as shown in (2-3) of FIG. 2, in the unexposed areas, the condensation reaction is suppressed by the ligand R3 of the metal-containing film, and the metal-containing film does not solidify and remains in a soluble state. In the development process, a negative resist film is processed, and the unexposed areas with a soluble metal-containing film are removed by a wet process or a dry process, leaving the exposed areas with an insoluble metal-containing film. Thereby, a metal-containing film (tin oxide resist film) with a predetermined pattern is formed.

[0028] The sensitivity of the tin oxide resist film correlates with the binding energy between Sn and the ligand R3 in the film. For example, the oligomer shown in (1-2) of FIG. 2 is terminated by the ligand R3. Therefore, as shown in (1-3) by exposure treatment (EUV), a large exposure amount is required to sufficiently desorb the ligand R3. This indicates that the binding energy between Sn and the ligand R3 in the film is high and the sensitivity of the metal-containing film is low.

[0029] In other words, the lower the binding energy between Sn and the ligand R3, the higher the sensitivity of the metal-containing resist film that can be provided. Therefore, from the perspective of increasing the sensitivity, a film structure with a low binding energy of the Sn-R bond is desirable. On the other hand, a film with a low binding energy of the Sn-R bond increases instability. For this reason, in the resist film formation method of the reference example, it is difficult to achieve both the stability of the film and high sensitivity.

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

[0031] <First Embodiment> [Method for Forming Resist Film] With reference to FIGS. 3 to 5, a substrate processing method for forming a metal-containing resist film according to the first embodiment will be described. 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. FIG. 4 is a diagram showing an example of a film cross-section in each step of forming a film according to the first embodiment. FIG. 5 is a diagram showing an example of a film structure in each step of forming a film according to the first embodiment. In FIG. 5, the film structure on the substrate W is shown by dividing the upper part of the substrate W into an exposed part and an unexposed part in each step. The upper part of FIG. 5 shows the film structure of the exposed part, and the lower part shows the film structure of the unexposed part. Further, hereinafter, a substrate processing method for forming a tin oxide resist film as an example of a metal-containing resist film will be described.

[0032] (Step S10) In step S10, the substrate W is prepared in the processing container 2. As shown in FIG. 4(a), the prepared substrate W has an underlayer film 101. The control unit 9 controls a transfer device (not shown) to transfer the substrate W having the underlayer film 101 to the processing container 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 first processing gas having a metal-containing precursor gas containing ligands R3 and R1 having different thermal reactivities with oxygen is supplied to the processing container 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.

[0034] The alkoxy group L contains an O—C m H n 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] The ligand R3 is a substance derived from the precursor contained in the metal-containing precursor gas and has an M—C a H b bond. M is a metal, and a and b are integers of 1 or more.

[0036] Ligand R1 is a substance derived from a precursor contained in a metal-containing precursor gas and has an M-C x H y bond. 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 contains a plurality of types of precursors including a first precursor having an M-C a H b bond and a second precursor having an M-C x H y bond. However, it is not limited to this, and the metal-containing precursor gas may contain one type of precursor having an M-C a H b bond and an M-C x H y bond.

[0039] As shown in (1-1) and (2-1) of FIG. 5, the metal-containing precursor gas contains a first precursor having an M-C a H b bond and a second precursor having an M-C x H y bond. In the first precursor, two alkoxy groups L and two ligands R3 are bonded to Sn, and in the second precursor, four ligands R1 are bonded to Sn. However, in the second precursor, at least one ligand R1 may be bonded to Sn, and the remaining bonds with Sn may not be ligands R1.

[0040] Ligand R1 has a first thermal reactivity, and ligand R3 has a second thermal reactivity lower than the first thermal reactivity. That is, ligand R1 reacts at a lower heating temperature than ligand R3. Also, ligand R3 has a first photoreactivity, and ligand R1 has a second photoreactivity lower than the first photoreactivity. That is, ligand R3 reacts with a smaller exposure amount than ligand R1.

[0041] The ligand R1 is an example of a second ligand having a first thermal reactivity. The ligand R3 is an example of a first ligand having a second thermal reactivity lower than the first thermal reactivity.

[0042] Here, the control unit 9 controls the gas source 61 to supply a first processing gas containing a metal-containing precursor gas into the processing vessel 2 through a plurality of holes 53 from the gas supply unit 5. Further, the control unit 9 controls the RF power supply 51 to supply RF power to the upper electrode (gas supply unit 5). Thereby, plasma is generated from the first processing gas in the processing vessel 2, and the generated plasma is irradiated to the substrate W.

[0043] (Step S12) In step S12, a metal-containing film 102 is formed on the surface of the substrate W by the polymerization reaction of the generated plasma (see FIG. 4(b)). The metal-containing film 102 contains the ligand R1 and the ligand R3. As shown in (1-2) and (2-2) of FIG. 5, the metal-containing film 102 is formed by deposition of a metal-containing oligomer containing 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. Thereby, a metal-containing film 102 containing two types of ligands having different thermal reactivities is formed.

[0044] Specifically, the metal-containing precursor gas may be, for example, two selected from Sn(OC4H9)4, Sn(OC4H9)2(CH3)2, Sn(OC4H9)2(C2H5)2, Sn(OC4H9)2(C3H8)2, Sn(OC4H9)2(C4H9)2, Sn(OC4H9)3(CH3)1, Sn(OC4H9)3, (C2H5)1, Sn(OC4H9)3(C3H8)1, Sn(OC4H9)3(C4H9)1, Sn(CH3)4, SnH(CH3)3, SnH2(CH3)2, Sn(C2H5)4, Sn(C3H8)4Sn(C4H9)4, Al(CH3)3, Co(C5H5)2, SnR4, SnHR3 (where R is -CH3, -C2H3, -C3H5, -C4H7, -C6H6). The two selected precursor gases are Sn-Ca H b Combination and Sn-C x H y has a relationship with the combination.

[0045] The first processing gas may contain an additive gas and / or an inert gas. The additive gas is at least one gas selected from H2, CH4, C2H2, C2H4, and C3H6. By adding the additive gas, M-C a H b and M-C x H y bonds can be formed. From the viewpoints of stability and cost, materials having desired M-CaHb bonds and M-CxHy bonds may not always be used as the metal-containing precursor gas. Therefore, by adding the additive gas and controlling the concentration, desired M-CaHb bonds and M-CxHy bonds and concentrations can be imparted. Thereby, it becomes possible to include desired bonds in the film without being restricted by the metal-containing precursor gas. Further, thereby, the degree of freedom in the selection of the thermal reactivity and the photoreactivity can be improved. The inert gas for the material is at least one gas selected from He, Ar, Ne, Xr, and N2.

[0046] An example of a recipe in the step of forming the 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 Processing chamber internal pressure: 100 mTorr (13.3 Pa) to 20 Torr (26.7 Pa) Next, the control unit 9 controls a transfer device (not shown) to carry out the substrate W from the processing chamber 2 of the plasma processing apparatus 1. Note that the processes from step S10 to step S12 are performed in the processing chamber 2 under 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. 4(c)). Specifically, the metal-containing film 102 is reacted with oxygen or water at a predetermined temperature to desorb the ligand R1 and convert it to an OH group, thereby forming an Sn-OH bond and removing the ligand R1. As a result, the metal-containing film 102A on the surface of the substrate W has a film structure in which the ligand R1 is removed from the metal-containing film 102 and the ligand R3 remains, as shown in (1-3) and (2-3) of Fig. 5.

[0049] Fig. 6 is a diagram showing an example of the 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 remaining film thickness 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 desorbs and is converted to an OH group and removed. Line RA shows the temperature dependence of the solubility of the metal-containing film terminated with ligand R1 for tin oxide. Line RB shows the temperature dependence of the solubility of the metal-containing film terminated with ligand R3 for tin oxide. As a result of the experiment, the metal-containing film terminated with ligand R1 for tin oxide shown by line RA changed to an insoluble film when the substrate W was controlled to 120°C or higher. On the other hand, the metal-containing film terminated with ligand R3 for tin oxide shown by line RB maintained a soluble film when the substrate W was controlled to 120°C or higher and less than 250°C, and changed to an insoluble film when the mounting table 3 was controlled to 250°C or higher.

[0050] Therefore, in step S13, by controlling the substrate W to a temperature of 120°C or higher and less than 250°C, the ligand R1 can be desorbed and removed, and a metal-containing film 102A of a metal-containing oligomer with the ligand R3 remaining can be formed. As a result, the solidification of the metal-containing film 102A is suppressed by the ligand R3 in the metal-containing film 102A. In this way, as shown in FIGS. 5(1-3) and (2-3), after the heat treatment (PDB), a metal-containing oligomer in which the ligand R3 and the OH group coexist can be formed. Thereby, a metal-containing film 102A (metal-containing resist film) with high photoreactivity (sensitivity) and excellent film stability can be formed in the subsequent exposure process.

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

[0052] As a result, in the exposed portion A, the bond between the highly photoreactive ligand R3 and Sn is broken, reacted with oxygen or water to form an Sn-OH bond, and the ligand R3 is desorbed and converted into an OH group. Further, the condensation reaction between the OH groups proceeds. As a result, as shown in FIGS. 5(1-4), the ligand R3 is removed from the film in the exposed portion A, and a metal-containing film 102A1 of a metal-containing oligomer having an Sn-OH bond is formed. Since the unexposed portion B is not irradiated with EUV, it has the same film structure as the metal-containing film 102A.

[0053] (Step S15) In step S15, the substrate W 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 of the exposed portion A, the film solidifies, and as shown in FIG. 4(e), an insoluble metal-containing resist film 102A2 is formed. (1-5) of FIG. 5 shows that the condensation reaction of the metal-containing oligomer in the exposed portion A is promoted by heat treatment (PEB), and an insoluble metal-containing resist film 102A2 (tin oxide resist film) having Sn-O bonds is formed.

[0055] On the other hand, in the unexposed portion B, the condensation reaction of the metal-containing oligomer is suppressed by the ligand R3 in the metal-containing film 102A, solubility is maintained, and developability is obtained. As a result, the metal-containing film 102A in the unexposed portion B becomes a film that can be removed by the development process in the next step.

[0056] (Step S16) In step S16, a development process is performed on the substrate W. Here, by the development process, the unexposed portion B is selectively removed (see FIG. 4(f)). As the development process, at least one of a wet process and a dry process can be used.

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

[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 and selectively remove the unexposed portion B. As the halogen-containing gas, at least one of HBr, HCl, and BCl3 can be used.

[0059] As described above, according to the film formation method according to the first embodiment, the metal-containing resist film 102A2 can be formed on the underlying film 101. The metal-containing film 102 formed by the plasma processing apparatus 1 can be a negative-type resist film capable of selectively removing the unexposed portion B.

[0060] Also, a metal-containing film having two types of ligands R1 and R3 with different thermal reactivities is formed, and by heat treatment (PDB), ligand R1 is desorbed and converted to an OH group. Further, by exposure treatment (EUV), ligand R3 is desorbed and converted to an OH group. Then, by heat treatment (PEB), the condensation reaction of the OH group is promoted, whereby a metal-containing resist film with high sensitivity and excellent stability can be formed.

[0061] FIG. 7 is a diagram showing an example of experimental results regarding the sensitivity of a metal-containing film. The horizontal axis in FIG. 7 indicates the exposure time, and the vertical axis indicates the remaining film thickness (thickness of the remaining film). The reference example indicated by the broken line in FIG. 7 shows the relationship between the exposure time and the remaining film thickness when the metal-containing film having one type of ligand R3 shown in (1-2) of FIG. 2 is subjected to exposure treatment (EUV).

[0062] The embodiment indicated by the solid line in FIG. 7 shows the relationship between the exposure time and the remaining film thickness when exposure treatment (EUV) is performed after removing ligand R1 by heat treatment (PDB) on the metal-containing film having two types of ligands R1 and R3 shown in (1-2) of FIG. 5.

[0063] The exposure amount increases as the exposure time becomes longer. In the experiment of FIG. 7, the remaining film thickness of the embodiment increased steeply with a smaller exposure amount than the remaining film thickness of the reference example. The timing at which the remaining film thickness increases steeply indicates that the metal-containing film switches from soluble to insoluble. That is, the earlier the timing at which the remaining film thickness increases steeply, the more it indicates that ligand R3 in the metal-containing film has been removed with a smaller exposure amount.

[0064] In the reference example, since it was necessary to break all the bonds of the ligand R3 in the film, the metal-containing film did not change to an insoluble film unless the exposure amount was increased. On the other hand, in the embodiment, since the timing at which the remaining film thickness increased steeply was earlier than that in the reference example, the bonds of the ligand R3 in the film could be broken by irradiating light with an exposure amount less than that in the reference example. That is, in the embodiment, a metal-containing resist film with higher sensitivity was obtained compared to the reference example. In the embodiment, since the ligand R1 had been previously detached and removed from the metal-containing film by heat treatment (PDB), an insoluble metal-containing resist film was obtained with an exposure amount less than that in the reference example.

[0065] <Second Embodiment> [Method for Forming Resist Film] Next, with reference to FIGS. 8 to 10, a substrate processing method for forming a metal-containing resist film according to the second embodiment will be described. FIG. 8 is a flowchart showing an example of a substrate processing method for forming a metal-containing resist film according to the second embodiment. FIG. 9 is a diagram showing an example of a film cross-section in each step of forming a film according to the second embodiment. FIG. 10 is a diagram showing an example of a film structure in each step of forming a film according to the second embodiment. In FIG. 10, the film structure on the substrate W in each step is shown by dividing the upper surface of the substrate W into an exposed portion and an unexposed portion. The upper row of FIG. 10 shows the film structure of the exposed portion, and the lower row shows the film structure of the unexposed portion. Further, hereinafter, a substrate processing method for forming a tin oxide resist film as an example of the metal-containing resist film will be described.

[0066] (Step S20) In step S20, the substrate W is prepared in the processing container 2. As shown in FIG. 9(a), the prepared substrate W has an underlying film 101.

[0067] (Step S21) In step S21, a first processing gas having a metal-containing precursor gas containing ligands R3 and R1 with different oxygen heat reactivities is supplied to the processing container 2. The metal-containing precursor gas may be an organometallic precursor gas containing oxygen. Further, 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 includes a first precursor having an M—C a H b bond and a second precursor having an M—C x H y bond. In the first precursor, two alkoxy groups L and two ligands R3 are bonded to Sn, and in the second precursor, four ligands R1 are bonded to Sn. However, in the second precursor, at least one ligand R1 may be bonded to Sn, and the remaining bonds with Sn may not be ligands R1.

[0069] Regarding the configuration of the metal-containing precursor gas and the first processing gas having the metal-containing precursor gas, since it is the same as the first processing gas used in the first embodiment, the description is omitted here.

[0070] (Step S22) In step S22, a metal-containing film 102 is formed on the surface of the substrate W by the polymerization reaction of the generated plasma (see FIG. 9(b)). The metal-containing film 102 contains the ligand R1 and the ligand R3. As shown in (1-2) and (2-2) of FIG. 10, the metal-containing film 102 is formed by depositing metal-containing oligomers containing 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. Thereby, a metal-containing film 102 containing two types of ligands with different thermal reactivities is formed.

[0071] An example of the recipe in the step of forming the 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 Processing chamber pressure: 100 mTorr (13.3 Pa) to 20 Torr (26.7 Pa) Note that the processes from step S20 to step S22 are performed in the processing chamber 2 under a reduced-pressure atmosphere.

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

[0074] As a result, in the exposed portion A, the bond between the highly photoreactive ligand R3 and Sn is broken, reacted with oxygen or water to form an Sn-OH bond, the ligand R3 is desorbed and converted to an OH group. Also, the condensation reaction between OH groups proceeds. Thereby, as shown in (1-3) of FIG. 10, the ligand R3 is removed from the film in the exposed portion A, and a metal-containing film 102B1 of a metal-containing oligomer having the ligand R1 and an Sn-OH bond is formed (see FIG. 9(c)). Since the unexposed portion B is not irradiated with EUV, it has the same film structure as the metal-containing film 102.

[0075] Note that in the exposure process, a part of the ligand R1 may be desorbed and converted to an OH group and removed, but at least a part of the ligand R1 remains in the metal-containing film 102B1.

[0076] (Step S24) In step S24, the substrate W subjected to the exposure process (EUV) is subjected to a heat treatment (Post Exposure Bake: PEB). Here, the bond between the highly thermoreactive ligand R1 and Sn is broken, reacted with oxygen or water to form an Sn-OH bond, the ligand R1 is desorbed and converted to an OH group. Also, the condensation reaction of the metal-containing oligomer in the exposed portion A is promoted in response to the desorption of the ligand R1.

[0077] That is, by promoting the condensation reaction between Sn-OH bonds in the film of the exposed portion A, the film solidifies, and as shown in FIG. 9(d), an insoluble metal-containing resist film 102B2 is formed. (1-4) of FIG. 10 shows that after the ligand R1 is desorbed and removed by heat treatment (PEB), the condensation reaction of the metal-containing oligomer in the exposed portion A proceeds, and an insoluble metal-containing resist film 102B2 of tin oxide having Sn-O bonds is formed.

[0078] On the other hand, in the unexposed portion B, the highly thermally reactive ligand R1 is desorbed and removed by heat treatment (PEB), but as shown in (2-3) of FIG. 10, the ligand R3 with low thermal reactivity remains in the film. Therefore, a metal-containing film 102B having the ligand R3 is formed in the unexposed portion B (see FIG. 9(d)). Due to the ligand R3 in the metal-containing film 102B, the condensation reaction is suppressed, solubility is maintained, and developability is obtained. As a result, the metal-containing film 102B in the unexposed portion B becomes a film that can be removed by the development process in the next step.

[0079] (Step S25) In step S25, a development process is performed on the substrate W. Here, the unexposed portion B (see FIG. 9(e)) is selectively removed by the development process. As the development process, at least one of a wet process and a dry process can be used.

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

[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. As the halogen-containing gas, at least one of HBr and HCl can be used.

[0082] As described above, according to the film formation method according to the second embodiment, the metal-containing resist film 102B2 can be formed on the base film 101. The metal-containing film 102 formed by the plasma processing apparatus 1 can be a negative-type resist film capable of selectively removing the unexposed portion B.

[0083] Also, a metal-containing film having two types of ligands R1 and R3 with different thermal reactivities is formed, and by exposure treatment (EUV), the ligand R3 is desorbed and converted into an OH group. Then, by heat treatment (PEB), the ligand R1 is desorbed and converted into an OH group and removed, thereby promoting the condensation reaction between the OH groups, and a metal-containing resist film with high sensitivity and excellent stability can be formed.

[0084] In the film formation method according to the first embodiment, heat treatment (PDB) is performed before the exposure treatment (EUV). Therefore, in the first embodiment, the ligand R1 in the metal-containing film is first desorbed and removed by the heat treatment (PDB), and then the ligand R3 is desorbed and removed by the exposure treatment.

[0085] On the other hand, 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 R3 in the metal-containing film is first desorbed and removed by the exposure treatment (EUV), and then the ligand R1 is desorbed and removed by the heat treatment (PEB).

[0086] Thus, in the second embodiment, the ligand R3 is desorbed and removed from the metal-containing film before the ligand R1. Since the ligand R3 has a larger number of carbons (C) than the ligand R1, by desorbing and removing the ligand R3 from the metal-containing film first, a metal-containing film with a lower carbon content can be obtained, 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 in the heat treatment (PDB), exposure treatment (EUV), and heat treatment (PEB) for detaching and removing the ligand R1 or ligand R3, oxidizing agents such as H2O and O2 may or may not be used. For example, by performing the heat treatment (PDB), exposure treatment (EUV), and heat treatment (PEB) in an air atmosphere, the water or oxygen component in the air may be used to detach the ligand R1 or ligand R3 and convert it to an OH group. Alternatively, the hydrogen or oxygen component contained in the metal-containing film 102 may be used to detach the ligand R1 or ligand R3 and convert it to an OH group.

[0088] When the number of carbon atoms in the ligand R1 is increased from 4 to 5 and 6, the temperature at which the metal-containing film having the ligand R1 maintains solubility can be raised to about 310°C.

[0089] Thus, by changing the number of carbon atoms in the ligand R1, in the heat treatment (PDB), the substrate W can be controlled at a temperature of 120°C or higher and lower than 310°C. Thereby, a metal-containing film having desired film stability and high sensitivity can be formed.

[0090] As described above, according to the substrate processing method and the plasma processing apparatus of the present embodiment, a metal-containing film capable of achieving both film stability and high sensitivity can be formed.

[0091] The substrate processing method and the plasma processing apparatus according to the embodiments disclosed this time should be considered to be illustrative in all respects and not restrictive. The embodiments can be modified and improved in various forms without departing from the scope and gist of the appended claims. The matters described in the above plurality of embodiments can also adopt other configurations within a non-contradictory range and can be combined within a non-contradictory range.

Description of Reference Numerals

[0092] 1 Plasma processing apparatus 2 Processing chamber 3 Mounting table 5 Gas supply unit 9 Control unit 101 Substrate film 102 Metal-containing film 102A2 Metal-containing resist film 102B2 Metal-containing resist film A Exposure part B Unexposed part W Substrate

Claims

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

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

3. In the step (C), after removing the second ligand from the metal-containing film, in the step (D), removing the first ligand from the exposed portion, The substrate processing method according to Claim 2.

4. In the step (C), after converting the second ligand contained in the metal-containing film into an OH group, in the step (D), converting the first ligand contained in the exposed portion into an OH group, (E) heat-treating the metal-containing film after the step (D) to cause the OH groups to undergo a condensation reaction, The substrate processing method according to Claim 3.

5. In the step (D), after removing the first ligand from the exposed portion, in the step (C), removing the second ligand from the metal-containing film, The substrate processing method according to Claim 2.

6. In the step (D), after converting the first ligand contained in the exposed portion into an OH group, in the step (C), converting the second ligand contained in the metal-containing film into an OH group, and causing the OH groups to undergo a condensation reaction, The substrate processing method according to Claim 5.

7. In the step (C), controlling the temperature of the stage on which the substrate is placed to a temperature of 120°C or higher and lower than 310°C, The substrate processing method according to any one of Claims 1 to 6.

8. In the step (C), controlling the temperature of the stage on which the substrate is placed to a temperature of 120°C or higher and lower than 250°C, The substrate processing method according to Claim 7.

9. In the step (B), supplying a first processing gas having a metal-containing precursor gas including the first ligand and the second ligand having different thermal reactivities with oxygen, generating plasma of the first processing gas, and forming a metal-containing film including oxygen, the first ligand, and the second ligand on the surface of the substrate by plasma polymerization reaction. The substrate processing method according to any one of claims 1 to 6.

10. The metal-containing precursor gas is M-C ａ H ｂ bond, and M-C ｘ H ｙ bond, where 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 The substrate processing method according to claim 9.

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

12. The metal-containing precursor gas contains a plurality of types of precursors including a first precursor having an M-C ａ H ｂ bond and a second precursor having an M-C ｘ H ｙ bond. The substrate processing method according to claim 10.

13. The metal-containing precursor gas is M-C ａ H ｂ bond and M-C ｘ H ｙ and contains one type of precursor having a bond The substrate processing method according to claim 10.

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

15. The inside of the processing container where (D) is performed is under vacuum. The substrate processing method according to any one of claims 1 to 6.

16. In (E), the substrate is controlled to a temperature of -10°C or higher and 310°C or lower. The substrate processing method according to claim 4.

17. The first processing gas contains an additive gas and / or an inert gas. The substrate processing method according to claim 9.

18. The additive gas is H ２ , CH ４ , C ２ H ２ , C ２ H ４ , C ３ H ６ and is at least one gas selected from The inert gas is at least one gas selected from He, Ar, Ne, Xr, N ２ and is a gas selected from the group consisting of The substrate processing method according to claim 17.

19. (F) Selectively removing the unexposed portion from the metal-containing film. The substrate processing method according to any one of claims 1 to 6.

20. A processing container, A mounting table for mounting the substrate, A gas supply unit for supplying gas into the processing container, A plasma source for supplying power through an upper electrode provided on the top wall of the processing container, A control unit, and has The control unit, (A) Preparing the substrate on the mounting table in the processing container; (B) Supplying a first processing gas having a metal-containing precursor gas containing a first ligand and a second ligand with different thermal reactivities with oxygen from the gas supply unit, supplying power from the plasma source through 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 oxygen, the first ligand, and the second ligand on the surface of the substrate. A plasma processing apparatus for controlling.

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

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