Substrate processing method and substrate processing apparatus

Abstract

The present application provides a substrate processing method and a substrate processing apparatus capable of suppressing shape defects of a side wall of a recess in etching. A substrate processing method according to an exemplary embodiment is a method of processing a substrate provided with an etching target film and a mask having an opening provided on the etching target film. The method includes the following steps: step (a) of forming a first layer containing nitrogen atoms and hydrogen atoms on a side wall of a recess provided in the etching target film corresponding to the opening using a first processing gas; step (b) of modifying the first layer to a second layer using a second processing gas including a halogen-containing gas after step (a); and step (c) of etching the recess using a third processing gas after step (b).

Description

Technical Field

[0001] The exemplary embodiments of this disclosure relate to a substrate processing method and a substrate processing apparatus. Background Technology

[0002] Patent Document 1 discloses a method for forming a recess in a dielectric layer by etching. In this method, a mask is formed on the dielectric layer. Then, a silicon-containing protective coating is formed on the mask. Next, the recess is formed by etching using the mask and the silicon-containing protective coating.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2008-60566 Summary of the Invention

[0006] The problem the invention aims to solve

[0007] This disclosure provides a technique for suppressing poor sidewall shape in the etching of recesses.

[0008] Solution for solving the problem

[0009] In one exemplary embodiment, a substrate processing method is provided. The substrate processing method is a method of processing a substrate having an etch target film and a mask disposed on the etch target film and having an opening. The substrate processing method includes the following steps: step (a), forming a first layer comprising nitrogen atoms and hydrogen atoms on the sidewalls of a recess in the etch target film corresponding to the opening using a first processing gas; step (b), after step (a), modifying the first layer into a second layer using a second processing gas comprising a halogen-containing gas; and step (c), after step (b), etching the recess using a third processing gas.

[0010] The effects of the invention

[0011] According to an exemplary embodiment, it is possible to suppress poor shape of the sidewalls of the recesses during etching. Attached Figure Description

[0012] Figure 1 This is a diagram that schematically illustrates a substrate processing apparatus according to an exemplary embodiment.

[0013] Figure 2 This is a diagram that schematically illustrates a substrate processing apparatus according to an exemplary embodiment.

[0014] Figure 3 This is a flowchart illustrating a substrate processing method according to an exemplary embodiment.

[0015] Figure 4 This is a partially enlarged cross-sectional view of a substrate as an example.

[0016] Figure 5 This is a cross-sectional view showing a step of a substrate processing method according to an exemplary embodiment.

[0017] Figure 6 This is a cross-sectional view showing a step of a substrate processing method according to an exemplary embodiment.

[0018] Figure 7 This is a cross-sectional view showing a step of a substrate processing method according to an exemplary embodiment.

[0019] Figure 8 This is a partially enlarged cross-sectional view of a substrate obtained by performing a substrate processing method according to an exemplary embodiment. Detailed Implementation

[0020] The following describes various exemplary implementation methods.

[0021] In one exemplary embodiment, the substrate processing method is a method of processing a substrate having an etch target film and a mask disposed on the etch target film and having an opening. The substrate processing method includes the following steps: step (a), forming a first layer containing nitrogen atoms and hydrogen atoms on the sidewall of a recess disposed in the etch target film corresponding to the opening using a first processing gas; step (b), after step (a), modifying the first layer into a second layer using a second processing gas including a halogen-containing gas; and step (c), after step (b), etching the recess using a third processing gas.

[0022] According to the method of the described embodiment, in step (c), since a second layer is formed on the sidewall of the recess, the etching of the sidewall of the recess is suppressed. Therefore, it is possible to suppress shape defects of the sidewall of the recess during etching.

[0023] Alternatively, in step (a), a first plasma generated from the first processing gas can be used; in step (c), a second plasma generated from the third processing gas can be used; and in step (b), no plasma is generated, and the second processing gas comprising the halogen-containing gas is used. In this case, in step (b), since no plasma is generated, the etching of the mask by the plasma is suppressed.

[0024] Alternatively, the method may further include repeating steps (a), (b), and (c) after step (c). In this case, a deep recess can be formed.

[0025] Alternatively, step (c) and step (a) following step (c) can be performed simultaneously. In this case, a first layer can be formed on the sidewall of the recess while etching the recess.

[0026] Alternatively, the etched film may include a silicon-containing film. In this case, a recess can be formed in the silicon-containing film.

[0027] Alternatively, the silicon-containing membrane may include a nitrogen-containing silicon-containing membrane, and the first processing gas may contain hydrogen atoms.

[0028] Alternatively, the silicon-containing membrane may include a silicon-containing membrane that does not contain nitrogen, and the first processing gas may contain hydrogen atoms and nitrogen atoms.

[0029] Alternatively, the halogen-containing gas may include polar halides. In this case, the reactivity of the halogen-containing gas with the first layer becomes higher.

[0030] Alternatively, the halide may include hydrogen halide.

[0031] Alternatively, the first layer may contain ammonia or a compound having an amino group.

[0032] Alternatively, the second layer may contain ammonium halide or amine halide.

[0033] Alternatively, in step (c), a bias power may be applied to the substrate support portion used to support the substrate. In this case, the recesses can be selectively etched.

[0034] In one exemplary embodiment, the substrate processing apparatus includes: a chamber; a substrate support for supporting a substrate within the chamber, the substrate having an etch target film and a mask disposed on the etch target film and having an opening; a gas supply unit configured to supply at least one of a first processing gas, a second processing gas, and a third processing gas into the chamber, the second processing gas including a halogen-containing gas; and a control unit configured to control the gas supply unit to perform the following steps: step (a), using the first processing gas to form a first layer comprising nitrogen atoms and hydrogen atoms on the sidewall of a recess disposed on the etch target film corresponding to the opening; step (b), after step (a), using the second processing gas to modify the first layer into a second layer; and step (c), after step (b), using the third processing gas to etch the recess.

[0035] In one exemplary embodiment, the substrate processing method is a method for processing a substrate having an etch target film and a mask disposed on the etch target film and having an opening. The substrate processing method includes the following steps: step (a), exposing the substrate to a first processing gas capable of forming a first layer containing nitrogen and hydrogen atoms on the sidewalls of a recess in the etch target film corresponding to the opening; and step (b), after step (a), exposing the substrate to a second processing gas including a halogen-containing gas capable of modifying the first layer into a second layer; and step (c), after step (b), exposing the substrate to a third processing gas capable of etching the recess.

[0036] The various exemplary embodiments will now be described in detail with reference to the accompanying drawings. Furthermore, the same or equivalent parts will be labeled with the same reference numerals in the drawings.

[0037] Figure 1 and Figure 2 This is a diagram that schematically illustrates a substrate processing apparatus according to an exemplary embodiment. The substrate processing apparatus of this embodiment is, for example, a plasma processing system.

[0038] In one embodiment, the plasma processing system includes a plasma processing apparatus 1 and a control unit 2. The plasma processing apparatus 1 includes a plasma processing chamber 10, a substrate support 11, and a plasma generation unit 12. The plasma processing chamber 10 has a plasma processing space. Furthermore, the plasma processing chamber 10 has at least one gas supply port for supplying at least one processing gas to the plasma processing space, and at least one gas outlet for discharging gas from the plasma processing space. The gas supply port is connected to the gas supply unit 20 (described later), and the gas outlet is connected to the exhaust system 40 (described later). The substrate support 11 is disposed within the plasma processing space and has a substrate support surface for supporting a substrate.

[0039] The plasma generation unit 12 is configured to generate plasma using at least one processing gas supplied to the plasma processing space. The plasma generated in the plasma processing space can be capacitively coupled plasma (CCP), inductively coupled plasma (ICP), ECR plasma (Electron-Cyclotron-resonance plasma), Helicon Wave Plasma (HWP), or surface wave plasma (SWP), etc. Furthermore, various types of plasma generation units, including AC (Alternating Current) plasma generation units and DC (Direct Current) plasma generation units, can be used. In one embodiment, the AC signal (AC power) used in the AC plasma generation unit has a frequency in the range of 100 kHz to 10 GHz. Therefore, the AC signal includes RF (Radio Frequency) signals and microwave signals. In one embodiment, the RF signal has a frequency in the range of 200 kHz to 150 MHz.

[0040] The control unit 2 processes computer-executable commands that cause the plasma processing apparatus 1 to perform the various processes described herein. The control unit 2 can be configured to control the various elements of the plasma processing apparatus 1 to perform the various processes described herein. In one embodiment, the control unit 2 may be partially or entirely included in the plasma processing apparatus 1. The control unit 2 may, for example, include a computer 2a. The computer 2a may, for example, include a processing unit (CPU: Central Processing Unit) 2a1, a storage unit 2a2, and a communication interface 2a3. The processing unit 2a1 can be configured to perform various control actions based on programs stored in the storage unit 2a2. The storage unit 2a2 may include RAM (Random Access Memory), ROM (Read Only Memory), HDD (Hard Disk Drive), SSD (Solid State Drive), or combinations thereof. The communication interface 2a3 can communicate with the plasma processing apparatus 1 via a communication line such as a LAN (Local Area Network).

[0041] The following describes a structural example of a plasma processing system.

[0042] The plasma processing system includes a capacitively coupled plasma processing device 1 and a control unit 2. The capacitively coupled plasma processing device 1 includes a plasma processing chamber 10, a gas supply unit 20, a power supply 30, and an exhaust system 40. Additionally, the plasma processing device 1 includes a substrate support 11 and a gas inlet. The gas inlet is configured to introduce at least one processing gas into the plasma processing chamber 10. The gas inlet includes a spray head 13. The substrate support 11 is disposed within the plasma processing chamber 10. The spray head 13 is disposed above the substrate support 11. In one embodiment, the spray head 13 constitutes at least a portion of the ceiling of the plasma processing chamber 10. The plasma processing chamber 10 has a plasma processing space 10s defined by the spray head 13, the sidewall 10a of the plasma processing chamber 10, and the substrate support 11. The plasma processing chamber 10 has at least one gas supply port for supplying at least one processing gas to the plasma processing space 10s and at least one gas outlet for discharging gas from the plasma processing space. The sidewall 10a is grounded. The spray head 13 and the substrate support 11 are electrically insulated from the housing of the plasma processing chamber 10.

[0043] The substrate support portion 11 includes a main body portion 111 and a ring assembly 112. The main body portion 111 has a central region (substrate support surface) 111a for supporting a substrate (wafer) W, and an annular region (ring support surface) 111b for supporting the ring assembly 112. When viewed from above, the annular region 111b of the main body portion 111 surrounds the central region 111a of the main body portion 111. The substrate W is disposed on the central region 111a of the main body portion 111, and the ring assembly 112 is disposed on the annular region 111b of the main body portion 111 in such a way that it surrounds the substrate W on the central region 111a of the main body portion 111. In one embodiment, the main body portion 111 includes a base and an electrostatic chuck. The base includes a conductive member. The conductive member of the base functions as a lower electrode. The electrostatic chuck is disposed on the base. The upper surface of the electrostatic chuck has the substrate support surface 111a. The ring assembly 112 includes one or more annular members. At least one of the one or more annular members is an edge ring. Additionally, although not shown in the figures, the substrate support 11 may include a temperature adjustment module configured to adjust at least one of the electrostatic chuck, the ring assembly 112, and the substrate to a target temperature. The temperature adjustment module may include a heater, a heat transfer medium, a flow path, or a combination thereof. A heat transfer fluid such as brine or gas flows through the flow path. Furthermore, the substrate support 11 may include a heat transfer gas supply section configured to supply heat transfer gas between the back surface of the substrate W and the substrate support surface 111a.

[0044] The spray head 13 is configured to introduce at least one processing gas from the gas supply unit 20 into the plasma processing space 10s. The spray head 13 has at least one gas supply port 13a, at least one gas diffusion chamber 13b, and a plurality of gas inlets 13c. The processing gas supplied to the gas supply port 13a passes through the gas diffusion chamber 13b and is then introduced into the plasma processing space 10s through the plurality of gas inlets 13c. Additionally, the spray head 13 includes a conductive member. The conductive member of the spray head 13 functions as an upper electrode. Furthermore, in addition to the spray head 13, the gas inlet may also include one or more side gas injectors (SGIs) mounted on one or more openings formed in the sidewall 10a.

[0045] The gas supply unit 20 may include at least one gas source 21 and at least one flow controller 22. In one embodiment, the gas supply unit 20 is configured to supply at least one type of process gas from its respective gas source 21 to the spray head 13 via its respective flow controller 22. Each flow controller 22 may, for example, include a mass flow controller or a pressure-controlled flow controller. Furthermore, the gas supply unit 20 may also include one or more flow modulation devices for modulating or pulsedizing the flow rate of the at least one type of process gas.

[0046] The power supply 30 includes an RF power supply 31 coupled to the plasma processing chamber 10 via at least one impedance matching circuit. The RF power supply 31 is configured to supply at least one RF signal (RF power), such as an RF source signal and an RF bias signal, to the conductive members of the substrate support 11 and / or the conductive members of the spray head 13. Plasma is thus formed from at least one processing gas supplied to the plasma processing space 10. Therefore, the RF power supply 31 can function as at least part of a plasma generation unit configured to generate plasma from one or more processing gases in the plasma processing chamber 10. Furthermore, by supplying a bias RF signal to the conductive members of the substrate support 11, a bias potential can be generated on the substrate W, thereby attracting the ionic components of the formed plasma to the substrate W.

[0047] In one embodiment, the RF power supply 31 includes a first RF generation unit 31a and a second RF generation unit 31b. The first RF generation unit 31a is configured to be coupled to a conductive member of the substrate support 11 and / or a conductive member of the spray head 13 via at least one impedance matching circuit to generate an RF source signal (RF source power) for generating plasma. In one embodiment, the RF source signal has a frequency in the range of 13MHz to 150MHz. In one embodiment, the first RF generation unit 31a may also be configured to generate multiple RF source signals with different frequencies. The generated one or more RF source signals are provided to the conductive member of the substrate support 11 and / or the conductive member of the spray head 13. The second RF generation unit 31b is configured to be coupled to a conductive member of the substrate support 11 via at least one impedance matching circuit to generate an RF bias signal (RF bias power). In one embodiment, the RF bias signal has a frequency lower than the frequency of the RF source signal. In one embodiment, the RF bias signal has a frequency in the range of 400kHz to 13.56MHz. In one embodiment, the second RF generation unit 31b may also be configured to generate multiple RF bias signals with different frequencies. One or more of the generated RF bias signals are provided to the conductive members of the substrate support unit 11. Additionally, in various embodiments, at least one of the RF source signal and the RF bias signal may be pulsed.

[0048] Alternatively, the power supply 30 may also include a DC power supply 32 coupled to the plasma processing chamber 10. The DC power supply 32 includes a first DC generating unit 32a and a second DC generating unit 32b. In one embodiment, the first DC generating unit 32a is configured to be connected to a conductive member of the substrate support 11 to generate a first DC signal. The generated first DC bias signal is applied to the conductive member of the substrate support 11. In one embodiment, the first DC signal may also be applied to other electrodes, such as electrodes within an electrostatic chuck. In one embodiment, the second DC generating unit 32b is configured to be connected to a conductive member of the spray head 13 to generate a second DC signal. The generated second DC signal is applied to the conductive member of the spray head 13. In various embodiments, at least one of the first DC signal and the second DC signal may be pulsed. Furthermore, in addition to the RF power supply 31, the first DC generating unit 32a and the second DC generating unit 32b may also be provided, or the first DC generating unit 32a may replace the second RF generating unit 31b.

[0049] The exhaust system 40 can be connected to a gas outlet 10e, for example, located at the bottom of the plasma processing chamber 10. The exhaust system 40 may include a pressure regulating valve and a vacuum pump. The pressure within the plasma processing space 10s is adjusted by the pressure regulating valve. The vacuum pump may include a turbomolecular pump, a dry pump, or a combination thereof.

[0050] Figure 3 This is a flowchart illustrating a substrate processing method according to an exemplary embodiment. Figure 3 The substrate processing method shown (hereinafter referred to as "method MT1") can be executed by the substrate processing apparatus of the above embodiment. Method MT1 can be applied to substrate W.

[0051] Figure 4 This is a partially enlarged cross-sectional view of a substrate as an example. For example... Figure 4 As shown, in one embodiment, the substrate W includes an etch target film RE and a mask MK. The mask MK is disposed on the etch target film RE.

[0052] The etched film RE may include a recess R1. The recess R1 has sidewalls R1s and a bottom R1b. The recess R1 may be an opening. The recess R1 is, for example, a hole or a trench. Similar to step ST3 described later, the recess R1 can be formed by plasma etching performed using the plasma processing apparatus 1. The etched film RE may also include multiple recesses R1.

[0053] The etching target film (RE) can include a silicon-containing film. The silicon-containing film can be any single-layer film selected from silicon oxide (SiO2), silicon nitride (SiN), silicon oxynitride (SiON), silicon carbide (SiC), silicon carbon nitride (SiCN), organosiloxane (SiOCH), and silicon (Si) films, or it can be a stacked film comprising at least two single-layer films. The silicon-containing film can also be a multilayer film composed of at least two silicon-containing films arranged alternately. Furthermore, silicon nitride (SiN), silicon oxynitride (SiON), or silicon carbon nitride (SiCN) films are silicon-containing films containing nitrogen. Silicon oxide (SiO2), silicon carbide (SiC), organosiloxane (SiOCH), or silicon (Si) films are silicon-containing films that do not contain nitrogen. The silicon (Si) film can also be a monocrystalline silicon film, a polycrystalline silicon film (Poly-Si), or an amorphous silicon film (α-Si).

[0054] The mask MK has an opening OP. Corresponding to the opening OP, a recess R1 is provided on the etchable film RE. The width of the opening OP can be, for example, 100 nm or less. The distance between adjacent openings OP can be, for example, 100 nm or less.

[0055] The mask MK may include an organic film. The organic film may include at least one of a spin-on carbon (SOC) film and an amorphous carbon film.

[0056] Below, refer to Figures 3-8 The method MT1 will be described using the substrate processing apparatus described in the above embodiment as an example of applying method MT1 to substrate W. Figures 5-7 These are cross-sectional views illustrating a step in a substrate processing method according to an exemplary embodiment. Figure 8 This is a partially enlarged cross-sectional view of a substrate obtained by performing a substrate processing method according to an exemplary embodiment. When using the plasma processing apparatus 1, method MT1 can be executed in the plasma processing apparatus 1 by controlling each part of the plasma processing apparatus 1 through the control unit 2. In method MT1, as... Figure 2 As shown, the substrate W disposed on the substrate support 11 within the plasma processing chamber 10 is processed. The substrate W can be etched using method MT1.

[0057] like Figure 3 As shown, method MT1 includes steps ST1, ST2, ST3, and ST4. Steps ST1 to ST4 can be executed sequentially. Step ST4 can also be performed simultaneously with step ST3. Step ST3 can also be performed simultaneously with step ST1 following step ST3. In steps ST1 to ST4, the substrate W can be processed in-situ. In steps ST1 to ST4, the temperature of the substrate support portion 11 used to support the substrate W can be adjusted to below 30°C.

[0058] like Figure 5 As shown, in process ST1, for example, a first plasma P1 is used to form a first layer F1 on the sidewall R1s of the recess R1 of the substrate W. In process ST1, the substrate W can be exposed to the first plasma P1. The first plasma P1 can form the first layer F1 on the sidewall R1s of the recess R1 of the substrate W. The first plasma P1 is a plasma generated from a first processing gas. The first plasma P1 can be generated by the plasma generation unit 12 of the plasma processing apparatus 1. The first processing gas can be supplied from the gas supply unit 20 of the plasma processing apparatus 1 into the plasma processing chamber 10.

[0059] The first processing gas may contain at least one of hydrogen atoms and nitrogen atoms. The first processing gas may include at least one of hydrogen-containing gas, nitrogen-containing gas, oxygen-containing gas, and fluorine-containing gas. The hydrogen-containing gas may include H2 gas. The nitrogen-containing gas may include N2 gas. The gas containing both hydrogen and nitrogen atoms may include ammonia (NH3). The oxygen-containing gas may include at least one of O2 gas, CO gas, and CO2 gas. The fluorine-containing gas may include fluorocarbon gas. The fluorocarbon gas may include at least one of C4F6 gas, C4F8 gas, C3F8 gas, and CF4 gas. The first processing gas may not include hydrogen halides. When the etched film RE includes a nitrogen-containing silicon film, such as a silicon nitride film, the first processing gas may also contain hydrogen atoms. In this case, the first layer F1 contains nitrogen atoms from the silicon film and hydrogen atoms from the first processing gas. When the etched film RE includes a non-nitrogen-containing silicon film, such as a silicon oxide film, the first processing gas may also contain hydrogen and nitrogen atoms. In this case, the first layer F1 contains hydrogen and nitrogen atoms from the first processing gas. If the etched target film RE contains hydrogen atoms, the first processing gas may not contain hydrogen atoms.

[0060] The first layer F1 contains nitrogen and hydrogen atoms. The first layer F1 may include ammonia (NH3) or a compound having an amino group (-NH2). The first layer F1 is, for example, an ammonia adsorption layer. The first layer F1 is formed as a result of the interaction (e.g., adsorption or chemical reaction) between the first plasma P1 and the etched film RE. Depending on the aspect ratio of the recess R1, the first plasma P1 is more difficult to reach the bottom R1b than the sidewalls R1s of the recess R1, therefore the first layer F1 is difficult to form at the bottom R1b of the recess R1.

[0061] Furthermore, since ammonia (NH3) gas is highly reactive, when ammonia (NH3) gas is used as the first processing gas, even without using the first plasma P1, it is expected that a first layer F1 comprising ammonia (NH3) or a compound having an amino group (-NH2) can be formed on the sidewall R1s of the recess R1 of the substrate W.

[0062] In step ST1, the first plasma P1 can also be used, similar to step ST3 described later, to form the recess R1 by etching. In this case, the bottom R1b of the recess R1 is etched, making it difficult to form the first layer F1 at the bottom R1b of the recess R1.

[0063] like Figure 6As shown, in step ST2, for example, without generating plasma, a second processing gas G2 is used to modify the first layer F1 into the second layer F2. Alternatively, in step ST2, without generating plasma, the substrate W can be exposed to the second processing gas G2. The second processing gas G2 is different from the first processing gas. The second processing gas G2 is capable of modifying the first layer F1 into the second layer F2. The second processing gas G2 can be supplied from the gas supply unit 20 of the plasma processing apparatus 1 into the plasma processing chamber 10.

[0064] The second processing gas G2 includes a halogen-containing gas. The halogen-containing gas may include polar halides. The halides may be hydrogen halides (HX: X is any one of F, Cl, Br, and I) or halogenated hydrocarbons (C... n H 2n+1 X: X is any one of F, Cl, Br, and I. N is an integer greater than or equal to 1. Halogenated hydrocarbons are, for example, CH3Br (bromomethane) or C2H5Cl (chloroethane). The second processing gas G2 may also not include fluorine compounds.

[0065] The second layer F2 can be formed by reacting a halogen-containing gas with the first layer F1. The second layer F2 can function as a protective layer against etching in the process ST3 described later. Since the second layer F2 is formed by modifying the first layer F1, it is difficult to form at the bottom R1b of the recess R1. The second layer F2 may also include ammonium halide (NH4X: X is any one of F, Cl, Br and I) or amine halide (NH2X: X is any one of F, Cl, Br and I).

[0066] After step ST2, purging can also be performed inside the plasma processing chamber 10. Purging gas can be supplied into the plasma processing chamber 10 from the gas supply unit 20 of the plasma processing apparatus 1.

[0067] like Figure 7 As shown, in step ST3, for example, a second plasma P2 is used to etch the bottom R1b of the recess R1. In step ST3, the substrate W can be exposed to the second plasma P2. The second plasma P2 can etch the bottom R1b of the recess R1. The second plasma P2 is a plasma generated from a third processing gas. The second plasma P2 can be generated by the plasma generation unit 12 of the plasma processing apparatus 1. The third processing gas can be supplied from the gas supply unit 20 of the plasma processing apparatus 1 into the plasma processing chamber 10. The third processing gas is different from the second processing gas G2. The third processing gas can be different from the first processing gas or the same as the first processing gas. Examples of the third processing gas are the same as examples of the first processing gas.

[0068] In process ST3, a bias power can also be applied to the substrate support portion 11 used to support the substrate W. This can be achieved by... Figure 2 A bias power is applied to the power supply 30. By applying the bias power, the etching rate of the bottom R1b of the recess R1 increases.

[0069] like Figure 8 As shown, in step ST4, it can also be determined whether the depth DP of the recess R1 has reached a threshold. For example, the depth DP of the recess R1 can be monitored by an end-point monitor or the like. This determination can be made by the control unit 2 of the substrate processing apparatus. If the depth DP of the recess R1 reaches the threshold, method MT1 ends. If the depth DP of the recess R1 does not reach the threshold, it returns to step ST1, and steps ST1 to ST4 are repeated. In step ST4, it can also be determined whether the number of repetitions of steps ST1 to ST3 has reached a threshold. In this way, method MT1 can also include repeating steps ST1, ST2, and ST3 after step ST3.

[0070] When process ST3 and process ST1 following process ST3 are performed simultaneously, the second plasma P2 also serves as the first plasma P1. As a result, the etching of the bottom R1b of the recess R1 and the formation of the first layer F1 are performed simultaneously.

[0071] After method MT1, the depth DP of the recess R1 can be 3 μm or more, and the aspect ratio of the recess R1 (the depth DP of the recess R1 relative to the width WD) can be 30 or more. After method MT1, the ratio of the thickness TH of the mask MK to the depth DP of the recess R1 (TH / DP) can be 1 / 5 or more.

[0072] According to the method MT1 of the above embodiment, in step ST3, since a second layer F2 is formed on the sidewall R1s of the recess R1, the etching of the sidewall R1s of the recess R1 is suppressed. Therefore, it is possible to suppress the shape defects (bending) of the sidewall R1s of the recess R1 during etching. Furthermore, in step ST2, since no plasma is generated, the halogen-containing gas does not dissociate. Therefore, the etching of the mask MK by the plasma is suppressed. Therefore, it is possible to suppress the decrease in the thickness TH of the mask MK after step ST2.

[0073] Furthermore, through the second layer F2 formed on the sidewall R1s of the recess R1, etching of the sidewall R1s of the recess R1 is suppressed. Although the bottom R1b of the recess R1 is etched, the etched area is not limited to the bottom R1b of the recess R1. For example, as... Figure 7As shown, by etching the bottom R1b of the recess R1, the sidewall R1s of the recess R1, where the second layer F2 is not formed, is newly exposed. Alternatively, the exposed sidewall R1s of the recess R1 can also be etched. Furthermore, when the depth-to-width ratio of the recess R1 is large, sometimes the second layer F2 forms above the sidewall R1s of the recess R1 at a location prone to shape defects (bending), but not below. In such cases, it is possible to etch not only the bottom R1b of the recess R1, but also the sidewall R1s of the recess R1 where the second layer F2 is not formed. When the depth-to-width ratio of the recess R1 is large, it easily becomes a conical shape where the size of the recess R1 decreases from the upper end of the recess R1 towards the bottom R1b. However, by etching the sidewall R1s of the recess R1, the size of the bottom R1b of the recess R1 can be increased.

[0074] The above descriptions illustrate various exemplary embodiments, but the embodiments are not limited to these exemplary embodiments. Various additions, omissions, substitutions, and modifications can be made. Furthermore, elements from different embodiments can be combined to form other embodiments.

[0075] The following describes various experiments conducted to evaluate method MT1. These experiments are not intended to limit this disclosure.

[0076] (First Experiment)

[0077] In the first experiment, a substrate W containing a silicon nitride film and a mask MK on the silicon nitride film was prepared. Then, the aforementioned method MT1 was performed on the substrate W using the plasma processing system described above. First, step ST1 was performed. In step ST1, the first processing gas was a mixture of hydrogen, oxygen, and a fluorocarbon gas. In step ST1, while forming a recess R1 on the silicon nitride film using a first plasma P1, a first layer F1 was formed on the sidewall R1s of the recess R1. Next, step ST2 was performed. In step ST2, the second processing gas was hydrogen ozonate (HBr) gas. In step ST2, the hydrogen ozonate gas reacted with the first layer F1 to modify the first layer F1 into a second layer F2. Next, step ST3 was performed. In step ST3, the third processing gas was the same as the first processing gas. In step ST3, while etching the bottom R1b of the recess R1, the first layer F1 was formed on the sidewall R1s of the recess R1. That is, process ST3 and process ST1, which follows process ST3, were performed simultaneously. Processes ST1 through ST3 were repeated.

[0078] (Second Experiment)

[0079] In the second experiment, argon was used instead of hydrogen ozonate as the second treatment gas. All other conditions were the same as in the first experiment.

[0080] (Experimental Results)

[0081] The cross-section of the recess R1 of the substrate W, to which method MT1 was performed in the first and second experiments, was observed, and the cross-section was measured. Figure 8 The maximum value of the width WD of the recess R1 and the thickness TH of the mask MK are shown. When dimensional defects (bending) of the sidewalls of the recess R1 are suppressed, the maximum value of the width WD of the recess R1 decreases. When etching of the mask MK is suppressed, the thickness TH of the mask MK increases. The measurement results are shown below.

[0082] The maximum value of the width WD of the recess R1 was 126 nm in the first experiment and 142 nm in the second experiment. The thickness TH of the mask MK was 803 nm in the first experiment and 788 nm in the second experiment. Compared with the second experiment, in the first experiment, the maximum value of the width WD of the recess R1 decreased, and the thickness TH of the mask MK increased. Therefore, it can be concluded that in the first experiment, the etching of the mask MK was suppressed, and the poor shape of the sidewalls of the recess R1 during etching was also suppressed.

[0083] Through the foregoing description, various embodiments of the present disclosure have been described in this specification for illustrative purposes. It is understood that various modifications can be made without departing from the scope and spirit of this disclosure. Therefore, the various embodiments disclosed in this specification are not intended to be limiting, and the true scope and spirit are shown in the appended claims.

[0084] Explanation of reference numerals in the attached figures

[0085] 2: Control unit; 10: Plasma processing chamber; 11: Substrate support unit; 20: Gas supply unit; F1: First layer; F2: Second layer; G2: Second processing gas; MK: Mask; MT1: Method; OP: Opening; R1: Recess; R1s: Sidewall; RE: Etching target film; W: Substrate.

Claims

1. A substrate processing method for processing a substrate having an etch target film and a mask, wherein the mask is disposed on the etch target film and has an opening, the substrate processing method comprising the following steps: Step (a) uses a first plasma generated from a first processing gas to form a first layer containing nitrogen and hydrogen atoms on the sidewall of a recess disposed in the etched object film corresponding to the opening; Step (b), after step (a), without generating plasma, uses a second processing gas including halogen-containing gas to modify the first layer into a second layer; as well as Step (c) is performed after step (b) by using a second plasma generated from a third processing gas to etch the recess.

2. The substrate processing method according to claim 1, characterized in that, The process (c) includes repeating the processes (a), (b), and (c).

3. The substrate processing method according to claim 2, characterized in that, The process (c) and the process (a) following the process (c) are performed simultaneously.

4. The substrate processing method according to any one of claims 1 to 3, characterized in that, The etched film includes a silicon-containing film.

5. The substrate processing method according to claim 4, characterized in that, The silicon-containing film includes a nitrogen-containing silicon-containing film. The first processing gas contains hydrogen atoms.

6. The substrate processing method according to claim 4, characterized in that, The silicon-containing film includes a nitrogen-free silicon-containing film. The first processing gas contains hydrogen atoms and nitrogen atoms.

7. The substrate processing method according to any one of claims 1 to 3, characterized in that, The halogen-containing gas includes polar halides.

8. The substrate processing method according to claim 7, characterized in that, The halides include hydrogen halides.

9. The substrate processing method according to any one of claims 1 to 3, characterized in that, The first layer contains ammonia or a compound having an amino group.

10. The substrate processing method according to any one of claims 1 to 3, characterized in that, The second layer contains ammonium halide or amine halide.

11. The substrate processing method according to any one of claims 1 to 3, characterized in that, In step (c), a bias power is applied to the substrate support portion used to support the substrate.

12. A substrate processing apparatus comprising: chamber; A substrate support portion for supporting a substrate within the cavity, the substrate having an etch target film and a mask disposed on the etch target film and having an opening; A gas supply unit is configured to supply at least one of a first processing gas, a second processing gas, and a third processing gas to the chamber, wherein the second processing gas includes a halogen-containing gas; and Control Department in, The control unit is configured to control the gas supply unit to perform the following steps: Step (a) uses a first plasma generated from the first processing gas to form a first layer containing nitrogen and hydrogen atoms on the sidewall of a recess provided in the etched target film corresponding to the opening; Step (b), after step (a), without generating plasma, uses the second processing gas to modify the first layer into a second layer; as well as Step (c) is performed after step (b) by using a second plasma generated from the third processing gas to etch the recess.

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