Classifications

• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P50/00—Etching of wafers, substrates or parts of devices
  • H10P50/20—Dry etching; Plasma etching; Reactive-ion etching
  • H10P50/24—Dry etching; Plasma etching; Reactive-ion etching of semiconductor materials
  • H10P50/242—Dry etching; Plasma etching; Reactive-ion etching of semiconductor materials of Group IV materials

Definitions

• An exemplary embodiment of the present disclosure relates to an etching method and an etching apparatus.
• Patent document 1 discloses a technique for etching a film in a substrate containing silicon using a mask containing amorphous carbon or an organic polymer.
• This disclosure provides technology to improve etching shapes.
• an etching method includes the steps of: (a) providing a substrate having an undercoat film, a silicon-containing film on the undercoat film, and a mask on the silicon-containing film in a chamber; (b) etching the silicon-containing film using a first plasma generated from a first process gas containing hydrogen fluoride gas and a tungsten-containing gas to form a recess; and (c) after step (b), further etching the silicon-containing film using a second plasma generated from a second process gas containing hydrogen fluoride gas, wherein the second process gas does not contain the tungsten-containing gas or contains the tungsten-containing gas at a flow rate less than the flow rate of the tungsten-containing gas in the first process gas.
• a technique for improving the etching shape can be provided.
• FIG. 1 is a diagram for explaining a configuration example of a capacitively coupled plasma processing apparatus.
• 2 is a flowchart showing an etching method according to the first embodiment.
• FIG. 1 is a diagram showing an example of a cross-sectional structure of the substrate W at the end of process ST13.
• FIG. 13 is an example of a timing chart in the case where the undercoat film UF contains silicon.
• 13 is another example of a timing chart in the case where the undercoat film UF contains silicon.
• 13 is an example of a timing chart in the case where the undercoat film contains a metal.
• FIG. 10 is a flowchart showing an etching method according to a second embodiment.
• FIG. 1 is a diagram showing the relationship between ion flux and ion energy.
• 4 is a timing chart showing an example of a source RF signal and a bias RF signal.
• 4 is a timing chart showing an example of a source RF signal and a bias DC signal.
• 10 is a flowchart showing an etching method according to a third embodiment.
• 13 is a diagram showing an example of a cross-sectional structure of the substrate W at the end of process ST32.
• FIG. 13 is a diagram showing an example of a cross-sectional structure of the substrate W at the end of process ST33.
• FIG. 13 is an example of a timing chart according to a third embodiment.
• an etching method includes the steps of: (a) providing a substrate having an undercoat film, a silicon-containing film on the undercoat film, and a mask on the silicon-containing film in a chamber; (b) etching the silicon-containing film using a first plasma generated from a first process gas containing hydrogen fluoride gas and a tungsten-containing gas to form a recess; and (c) after step (b), further etching the silicon-containing film using a second plasma generated from a second process gas containing hydrogen fluoride gas, wherein the second process gas does not contain a tungsten-containing gas or contains a tungsten-containing gas at a flow rate less than the flow rate of the tungsten-containing gas in the first process gas.
• the tungsten-containing gas includes WF6 .
• the first process gas further comprises a phosphorus-containing gas.
• the second process gas does not contain a phosphorus-containing gas or contains a phosphorus-containing gas at a flow rate that is less than the flow rate of the phosphorus-containing gas in the first process gas.
• the second process gas further includes xenon gas.
• the first process gas does not contain xenon gas or contains xenon gas at a flow rate that is less than the flow rate of xenon gas in the second process gas.
• step (b) is performed before the base film is exposed in the recess or until at least a portion of the base film is exposed in the recess.
• step (b) is performed until a portion of the base film is etched.
• a cycle including steps (b) and (c) is performed multiple times.
• step (b) etches the silicon-containing film while forming a first protrusion at a first position on the mask that reduces the width of the opening in the mask, and forming a second protrusion at a second position on the mask that is lower than the first position that reduces the width of the opening in the mask.
• step (b) an inverted tapered recess is formed in the silicon-containing film, and in step (c), the shape of the recess is made rectangular.
• an etching method includes the steps of: (a) providing a substrate having an undercoat film, a silicon-containing film on the undercoat film, and a mask on the silicon-containing film in a chamber; (b) etching the silicon-containing film with a first plasma generated from a first process gas to form a recess; and (c) after step (b), further etching the silicon-containing film with a second plasma generated from a second process gas, where the first process gas includes a single gas or a mixed gas including fluorine and hydrogen and a metal-containing gas, the second process gas includes a single gas or a mixed gas including fluorine and hydrogen, and the second process gas does not include the metal-containing gas or includes the metal-containing gas at a flow rate less than the flow rate of the metal-containing gas in the first process gas.
• the metal-containing gas includes at least one metal selected from the group consisting of tungsten, molybdenum, titanium, and ruthenium.
• the first process gas further comprises a phosphorus-containing gas.
• the second process gas does not contain a phosphorus-containing gas or contains a phosphorus-containing gas at a flow rate that is less than the flow rate of the phosphorus-containing gas in the first process gas.
• the second process gas further includes a noble gas.
• the noble gas may include at least one selected from the group consisting of argon gas, krypton gas, xenon gas, and radon gas.
• the first process gas does not contain a noble gas or contains a noble gas at a flow rate that is less than the flow rate of the noble gas in the second process gas.
• an etching apparatus in one exemplary embodiment, includes a chamber, a substrate support within the chamber, a plasma generating unit, and a controller configured to control the plasma generating unit, and the controller is configured to perform a process including the steps of: (a) providing a substrate having an undercoat film, a silicon-containing film on the undercoat film, and a mask on the silicon-containing film into the chamber; (b) etching the silicon-containing film using a first plasma generated from a first process gas containing hydrogen fluoride gas and a tungsten-containing gas to form a recess; and (c) after step (b), further etching the silicon-containing film using a second plasma generated from a second process gas containing hydrogen fluoride gas, the second process gas either not containing tungsten-containing gas or containing tungsten-containing gas at a flow rate less than the flow rate of the tungsten-containing gas in the first process gas.
• Fig. 1 is a diagram for explaining an example of the configuration of a capacitively coupled plasma processing apparatus.
• 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.
• the plasma processing device 1 also includes a substrate support unit 11 and a gas introduction unit.
• the gas introduction unit is configured to introduce at least one processing gas into the plasma processing chamber 10.
• the gas introduction unit includes a shower head 13.
• the substrate support unit 11 is disposed in the plasma processing chamber 10.
• the shower head 13 is disposed above the substrate support unit 11. In one embodiment, the shower head 13 constitutes at least a part of the ceiling of the plasma processing chamber 10.
• the plasma processing chamber 10 has a plasma processing space 10s defined by the shower head 13, a sidewall 10a of the plasma processing chamber 10, and the substrate support unit 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 exhaust port for exhausting gas from the plasma processing space.
• the plasma processing chamber 10 is grounded.
• the showerhead 13 and the substrate support 11 are electrically insulated from the housing of the plasma processing chamber 10.
• the substrate support 11 includes a main body 111 and a ring assembly 112.
• the main body 111 has a central region 111a for supporting the substrate W and an annular region 111b for supporting the ring assembly 112.
• a wafer is an example of a substrate W.
• the annular region 111b of the main body 111 surrounds the central region 111a of the main body 111 in a plan view.
• the substrate W is disposed on the central region 111a of the main body 111
• the ring assembly 112 is disposed on the annular region 111b of the main body 111 so as to surround the substrate W on the central region 111a of the main body 111. Therefore, the central region 111a is also called a substrate support surface for supporting the substrate W, and the annular region 111b is also called a ring support surface for supporting the ring assembly 112.
• the main body 111 includes a base 1110 and an electrostatic chuck 1111.
• the base 1110 includes a conductive member.
• the conductive member of the base 1110 may function as a lower electrode.
• the electrostatic chuck 1111 is disposed on the base 1110.
• the electrostatic chuck 1111 includes a ceramic member 1111a and an electrostatic electrode 1111b disposed within the ceramic member 1111a.
• the ceramic member 1111a has a central region 111a. In one embodiment, the ceramic member 1111a also has an annular region 111b. Note that other members surrounding the electrostatic chuck 1111, such as an annular electrostatic chuck or an annular insulating member, may have the annular region 111b.
• the ring assembly 112 may be disposed on the annular electrostatic chuck or the annular insulating member, or may be disposed on both the electrostatic chuck 1111 and the annular insulating member.
• At least one RF/DC electrode coupled to an RF (Radio Frequency) power source 31 and/or a DC (Direct Current) power source 32, described below, may also be disposed within the ceramic member 1111a.
• the at least one RF/DC electrode functions as a lower electrode.
• the RF/DC electrode is also called a bias electrode.
• the conductive member of the base 1110 and the at least one RF/DC electrode may function as multiple lower electrodes.
• the electrostatic electrode 1111b may function as a lower electrode.
• the substrate support 11 includes at least one lower electrode.
• the ring assembly 112 includes one or more annular members.
• the one or more annular members include one or more edge rings and at least one cover ring.
• the edge rings are formed of a conductive or insulating material, and the cover rings are formed of an insulating material.
• the substrate support 11 may also include a temperature adjustment module configured to adjust at least one of the electrostatic chuck 1111, 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 passage 1110a, or a combination thereof.
• a heat transfer fluid such as brine or a gas flows through the flow passage 1110a.
• the flow passage 1110a is formed in the base 1110, and one or more heaters are disposed in the ceramic member 1111a of the electrostatic chuck 1111.
• the substrate support 11 may also include a heat transfer gas supply configured to supply a heat transfer gas to a gap between the back surface of the substrate W and the central region 111a.
• the shower head 13 is configured to introduce at least one processing gas from the gas supply unit 20 into the plasma processing space 10s.
• the shower head 13 has at least one gas supply port 13a, at least one gas diffusion chamber 13b, and multiple gas inlets 13c.
• the processing gas supplied to the gas supply port 13a passes through the gas diffusion chamber 13b and is introduced into the plasma processing space 10s from the multiple gas inlets 13c.
• the shower head 13 also includes at least one upper electrode.
• the gas introduction unit may include, in addition to the shower head 13, one or more side gas injectors (SGI) attached to one or more openings formed in the sidewall 10a.
• SGI side gas injectors
• the gas supply 20 may include at least one gas source 21 and at least one flow controller 22.
• the gas supply 20 is configured to supply at least one process gas from a respective gas source 21 through a respective flow controller 22 to the showerhead 13.
• Each flow controller 22 may include, for example, a mass flow controller or a pressure-controlled flow controller.
• the gas supply 20 may include one or more flow modulation devices to modulate or pulse the flow rate of the at least one process gas.
• 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) to at least one lower electrode and/or at least one upper electrode. This causes a plasma to be formed from at least one processing gas supplied to the plasma processing space 10s.
• the RF power supply 31 can function as at least a part of a plasma generating unit configured to generate plasma from one or more processing gases in the plasma processing chamber 10.
• a bias RF signal to the at least one lower electrode, a bias potential is generated on the substrate W, and ion components in the formed plasma can be attracted to the substrate W.
• the RF power supply 31 includes a first RF generating unit 31a and a second RF generating unit 31b.
• the first RF generating unit 31a is coupled to at least one lower electrode and/or at least one upper electrode via at least one impedance matching circuit and configured to generate a source RF signal (source RF power) for plasma generation.
• the source RF signal has a frequency in the range of 10 MHz to 150 MHz.
• the first RF generating unit 31a may be configured to generate multiple source RF signals having different frequencies. The generated one or more source RF signals are supplied to at least one lower electrode and/or at least one upper electrode.
• the second RF generator 31b is coupled to at least one lower electrode via at least one impedance matching circuit and configured to generate a bias RF signal (bias RF power).
• the frequency of the bias RF signal may be the same as or different from the frequency of the source RF signal.
• the bias RF signal has a lower frequency than the frequency of the source RF signal.
• the bias RF signal has a frequency in the range of 100 kHz to 60 MHz.
• the second RF generator 31b may be configured to generate multiple bias RF signals having different frequencies.
• the generated one or more bias RF signals are provided to at least one lower electrode. Also, in various embodiments, at least one of the source RF signal and the bias RF signal may be pulsed.
• 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 generator 32a and a second DC generator 32b.
• the first DC generator 32a is connected to at least one lower electrode and configured to generate a first DC signal.
• the generated first DC signal is applied to the at least one lower electrode as a first bias DC signal.
• the second DC generator 32b is connected to at least one upper electrode and configured to generate a second DC signal.
• the generated second DC signal is applied to the at least one upper electrode.
• At least one of the first and second DC signals may be pulsed.
• a sequence of voltage pulses is applied to at least one lower electrode and/or at least one upper electrode.
• the voltage pulses may have a rectangular, trapezoidal, triangular or combination thereof pulse waveform.
• a waveform generator for generating a sequence of voltage pulses from the DC signal is connected between the first DC generator 32a and at least one lower electrode.
• the first DC generator 32a and the waveform generator constitute a voltage pulse generator.
• the second DC generator 32b and the waveform generator constitute a voltage pulse generator
• the voltage pulse generator is connected to at least one upper electrode.
• the voltage pulses may have a positive polarity or a negative polarity.
• the sequence of voltage pulses may also include one or more positive polarity voltage pulses and one or more negative polarity voltage pulses within one period.
• the first and second DC generating units 32a and 32b may be provided in addition to the RF power source 31, or the first DC generating unit 32a may be provided in place of the second RF generating unit 31b.
• the exhaust system 40 may be connected to, for example, a gas exhaust port 10e provided 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 in 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.
• the control unit 2 processes computer-executable instructions that cause the plasma processing apparatus 1 to perform the various steps described in this disclosure.
• the control unit 2 may be configured to control each element of the plasma processing apparatus 1 to perform the various steps described herein. In one embodiment, a part or all of the control unit 2 may be included in the plasma processing apparatus 1.
• the control unit 2 may include a processing unit 2a1, a storage unit 2a2, and a communication interface 2a3.
• the control unit 2 is realized, for example, by a computer 2a.
• the processing unit 2a1 may be configured to perform various control operations by reading a program from the storage unit 2a2 and executing the read program. This program may be stored in the storage unit 2a2 in advance, or may be acquired via a medium when necessary.
• the acquired program is stored in the storage unit 2a2 and is read from the storage unit 2a2 by the processing unit 2a1 and executed.
• the medium may be various storage media readable by the computer 2a, or may be a communication line connected to the communication interface 2a3.
• the processing unit 2a1 may be a CPU (Central Processing Unit).
• the memory unit 2a2 may include a RAM (Random Access Memory), a ROM (Read Only Memory), a HDD (Hard Disk Drive), a SSD (Solid State Drive), or a combination of these.
• the communication interface 2a3 may communicate with the plasma processing device 1 via a communication line such as a LAN (Local Area Network).
• First Embodiment Fig. 2 is a flow chart showing the etching method according to the first embodiment.
• the etching method includes a step ST11 of providing a substrate, a first etching step ST12, and a second etching step ST13.
• the processes in each of the steps ST11 to ST13 may be performed in the plasma processing system shown in Fig. 1. That is, the etching method according to the first embodiment may be performed using the plasma processing apparatus 1 as an etching apparatus.
• the etching method according to the first embodiment will be described by taking as an example a case where the control unit 2 controls each part of the plasma processing apparatus 1 to etch the substrate W.
• Step ST11 Providing a substrate
• the substrate W is provided in the plasma processing space 10s of the plasma processing apparatus 1.
• the substrate W is provided in the central region 111a of the substrate support 11.
• the substrate W is then held on the substrate support 11 by the electrostatic chuck 1111.
• FIG. 3 is a diagram showing an example of a cross-sectional structure of a substrate W.
• the substrate W shown in FIG. 3 may be provided.
• the substrate W includes a silicon-containing film SF formed on a base film UF as a film to be etched.
• the substrate W may further include a mask MF on the silicon-containing film SF.
• the substrate W may be used in the manufacture of semiconductor devices.
• the semiconductor devices include, for example, semiconductor memory devices such as DRAMs and 3D-NAND flash memories.
• the base film UF is, for example, a silicon wafer, an organic film formed on a silicon wafer, a dielectric film, a metal film, or a semiconductor film.
• the base film UF may be composed of multiple laminated films.
• the base film UF may contain silicon or a metal such as tungsten.
• the silicon-containing film SF is a film to be etched.
• the silicon-containing film SF includes a silicon oxide film, a silicon nitride film, a silicon oxynitride film, a polycrystalline silicon film, or a carbon-containing silicon film.
• the silicon-containing film SF may be composed of a plurality of laminated films.
• the silicon-containing film SF may include a silicon oxide film and a silicon nitride film that are alternately laminated.
• the silicon-containing film SF may include a silicon oxide film and a polycrystalline silicon film that are alternately laminated.
• the silicon-containing film SF may be a laminated film that includes a silicon nitride film, a silicon oxide film, and a polycrystalline silicon film.
• the mask MF is a film that functions as a mask in etching the silicon-containing film SF.
• the mask MF may be, for example, a hard mask.
• the mask MF may also be a carbon-containing mask and/or a metal-containing mask.
• the carbon-containing mask may be, for example, formed of at least one selected from the group consisting of spin-on carbon, tungsten carbide, amorphous carbon, and boron carbide.
• the metal-containing mask may be, for example, formed of at least one selected from the group consisting of titanium nitride, titanium oxide, and tungsten.
• the tungsten-containing mask may be, for example, formed of tungsten silicide (WSi) and/or tungsten carbide (WC).
• the mask MF may also be, for example, a boron-containing mask formed from silicon boride, boron nitride, or boron carbide.
• the mask MF defines at least one opening OP on the silicon-containing film SF.
• the opening OP is a space above the silicon-containing film SF and is surrounded by the sidewalls of the mask MF. That is, the upper surface of the silicon-containing film SF has an area covered by the mask MF and an area exposed at the bottom of the opening OP.
• the openings OP may have any shape when viewed from above the substrate W, i.e., when the substrate W is viewed from the top to the bottom in FIG. 3.
• the shape may be, for example, a circle, an ellipse, a rectangle, a line, or a combination of one or more of these.
• the mask MF may have multiple side walls that define multiple openings OP.
• the multiple openings OP may each have a linear shape and be arranged at regular intervals to form a line-and-space pattern.
• the multiple openings OP may also each have a hole shape and form an array pattern.
• Each film constituting the substrate W may be formed by CVD, ALD, spin coating, or the like.
• the opening OP may be formed by etching the mask MF.
• the mask MF may also be formed by lithography.
• Each of the above films may be flat or uneven.
• the substrate W may further have another film below the undercoat film UF, and the laminated film of the silicon-containing film SF and undercoat film UF may function as a multilayer mask. That is, the laminated film of the silicon-containing film SF and undercoat film UF may be used as a multilayer mask to etch the other film.
• At least a part of the process of forming each film of the substrate W may be performed within the space of the plasma processing chamber 10.
• the process of etching the mask MF to form the opening OP may be performed in the plasma processing chamber 10. That is, the opening OP and the etching of the silicon-containing film SF described below may be performed consecutively in the same chamber.
• the substrate W may be transported into the plasma processing space 10s of the plasma processing apparatus 1 and placed in the central region 111a of the substrate support 11 to provide the substrate.
• the temperature of the substrate support 11 is adjusted to a set temperature by the temperature control module.
• the set temperature may be, for example, 20°C or less, 0°C or less, -10°C or less, -20°C or less, -30°C or less, -40°C or less, -50°C or less, -60°C or less, or -70°C or less.
• adjusting or maintaining the temperature of the substrate support 11 includes setting the temperature of the heat transfer fluid flowing through the flow path 1110a and the heater temperature to their respective set temperatures, or to temperatures different from their respective set temperatures.
• the timing at which the heat transfer fluid starts to flow through the flow path 1110a may be before or after the substrate W is placed on the substrate support 11, or may be simultaneous with the time.
• the temperature of the substrate support 11 may also be adjusted to the set temperature before the process ST11. That is, the substrate W may be provided to the substrate support 11 after the temperature of the substrate support 11 is adjusted to the set temperature.
• Step ST12 First Etching
• the silicon-containing film SF is etched using plasma generated from a first processing gas.
• the first processing gas is supplied from the gas supply unit 20 into the plasma processing space 10s.
• the first processing gas contains hydrogen fluoride (HF) gas.
• the HF gas functions as an etchant.
• the temperature of the substrate support unit 11 is maintained at the set temperature adjusted in step ST11.
• a source RF signal is supplied to the lower electrode of the substrate support 11 and/or the upper electrode of the shower head 13.
• a high-frequency electric field is generated between the shower head 13 and the substrate support 11, and a first plasma is generated from the first processing gas in the plasma processing space 10s.
• a bias signal is supplied to the lower electrode of the substrate support 11, and a bias potential difference is generated between the plasma and the substrate W.
• the bias potential difference attracts active species such as ions and radicals in the plasma to the substrate W.
• the silicon-containing film SF is etched, and a recess is formed in the silicon-containing film SF based on the shape of the opening OP of the mask MF.
• the first etching may be performed before (for example, just before) the base film UF is exposed, or until at least a part of the base film UF is exposed. That is, the process ST12 may be ended before (for example, just before) the base film UF of the substrate W is exposed, or at the timing when at least a part of the base film UF is exposed.
• FIG. 4 is a diagram showing an example of the cross-sectional structure of the substrate W at the end of step ST12.
• the processing in step ST12 etches the portion of the silicon-containing film SF exposed at the opening OP in the depth direction (from top to bottom in FIG. 4), forming a recess RC.
• FIG. 4 shows a state in which the base film UF is not exposed at the end of step ST12. That is, step ST12 may be stopped in a state in which the silicon-containing film SF remains between the base film UF and the bottom of the recess RC, and step ST13 may be started in this state and performed during a period including the time when the base film UF is exposed.
• the base film UF may be exposed in the recess RC at the end of step ST12.
• a cycle including steps ST12 and ST13 may be performed multiple times until the base film UF is exposed or a part of the base film UF is etched.
• the source RF signal may have a frequency in the range of 10 MHz to 150 MHz. In one example, the source RF signal may have a frequency of 40 MHz or more or 60 MHz or more.
• the bias signal may be a bias RF signal supplied from the second RF generating unit 31b.
• the bias signal may also be a bias DC signal (e.g., a sequence of voltage pulses) supplied from the DC generating unit 32a.
• Both the source RF signal and the bias signal may be continuous waves or pulse waves, and one of the source RF signal and the bias signal may be a continuous wave and the other a pulse wave. When both the source RF signal and the bias signal are pulse waves, the periods of both pulse waves may be synchronized.
• the duty ratio of the pulse wave may be set appropriately, for example, 1 to 80%, or 5 to 50%.
• the duty ratio is the proportion of the period during which the power or voltage level is high in the pulse wave period.
• each voltage pulse in the sequence may have a rectangular, trapezoidal, triangular, or combination waveform.
• the polarity of the bias DC signal may be negative or positive, provided that the potential of the substrate W is set to provide a potential difference between the plasma and the substrate to attract ions.
• the HF gas contained in the first processing gas may have the largest flow rate (partial pressure) among the first processing gas (all other gases in the first processing gas excluding the inert gas when the first processing gas contains an inert gas).
• the flow rate of the HF gas may be 50 vol.% or more, 60 vol.% or more, 70 vol.% or more, 80 vol.% or more, 90 vol.% or more, or 95 vol.% or more with respect to the total flow rate of the first processing gas (all gases in the first processing gas excluding the inert gas when the first processing gas contains an inert gas).
• the flow rate of the HF gas may be less than 100 vol.%, 99.5 vol.% or less, 98 vol.% or less, or 96 vol.% or less with respect to the total flow rate of the first processing gas. In one example, the flow rate of the HF gas is adjusted to 70 vol.% or more and 96 vol.% or less with respect to the total flow rate of the first processing gas.
• the first process gas may further include at least one gas selected from the group consisting of a carbon-containing gas, an oxygen-containing gas, and a phosphorus-containing gas.
• the carbon-containing gas may be, for example, either or both of a fluorocarbon gas and a hydrofluorocarbon gas.
• the fluorocarbon gas may be at least one selected from the group consisting of CF4 gas, C2F2 gas, C2F4 gas , C3F6 gas , C3F8 gas , C4F6 gas, C4F8 gas , and C5F8 gas.
• the hydrofluorocarbon gas may be at least one selected from the group consisting of CHF3 gas , CH2F2 gas , CH3F gas , C2HF5 gas, C2H2F4 gas , C2H3F3 gas , C2H4F2 gas , C3HF7 gas , C3H2F2 gas, C3H2F4 gas , C3H2F6 gas , C3H3F5 gas , C4H2F6 gas , C4H5F5 gas , C4H2F8 gas , C5H2F6 gas, C5H2F10 gas , and C5H3F7 gas .
• the carbon-containing gas may be linear and have an unsaturated bond.
• the linear carbon-containing gas having an unsaturated bond may be, for example, at least one selected from the group consisting of C 3 F 6 (hexafluoropropene) gas, C 4 F 8 (octafluoro-1-butene, octafluoro-2-butene) gas, C 3 H 2 F 4 (1,3,3,3-tetrafluoropropene) gas, C 4 H 2 F 6 (trans-1,1,1,4,4,4-hexafluoro-2-butene) gas, C 4 F 8 O (pentafluoroethyl trifluorovinyl ether) gas, CF 3 COF gas (1,2,2,2-tetrafluoroethane-1-one), CHF 2 COF (difluoroacetic acid fluoride) gas, and COF 2 (carbonyl fluoride) gas.
• C 3 F 6 hexafluoropropene
• C 4 F 8 octafluoro-1-butene
• the oxygen-containing gas may be, for example, at least one gas selected from the group consisting of O 2 , CO, CO 2 , H 2 O, and H 2 O 2.
• the oxygen-containing gas may be an oxygen-containing gas other than H 2 O, for example, at least one gas selected from the group consisting of O 2 , CO, CO 2, and H 2 O 2.
• the flow rate of the oxygen-containing gas may be adjusted according to the flow rate of the carbon-containing gas.
• the phosphorus-containing gas is a gas containing phosphorus-containing molecules.
• the phosphorus-containing molecules may be oxides such as tetraphosphorus decaoxide (P 4 O 10 ), tetraphosphorus octoxide (P 4 O 8 ), and tetraphosphorus hexaoxide (P 4 O 6 ). Tetraphosphorus decaoxide is sometimes called diphosphorus pentoxide (P 2 O 5 ).
• the phosphorus-containing molecules may be halides (phosphorus halides) such as phosphorus trifluoride (PF 3 ), phosphorus pentafluoride (PF 5 ), phosphorus trichloride (PCl 3 ), phosphorus pentachloride (PCl 5 ), phosphorus tribromide (PBr 3 ), phosphorus pentabromide (PBr 5 ), and phosphorus iodide (PI 3 ). That is, the phosphorus-containing molecules may contain fluorine as a halogen element, such as phosphorus fluoride. Alternatively, the phosphorus-containing molecules may contain a halogen element other than fluorine as a halogen element.
• phosphorus halides such as phosphorus trifluoride (PF 3 ), phosphorus pentafluoride (PF 5 ), phosphorus trichloride (PCl 3 ), phosphorus pentachloride (PCl 5 ), phosphorus tribromide (PBr 3
• the phosphorus-containing molecule may be a phosphoryl halide such as phosphoryl fluoride ( POF3 ), phosphoryl chloride ( POCl3 ), or phosphoryl bromide ( POBr3 ).
• the phosphorus-containing molecule may be phosphine ( PH3 ), calcium phosphide ( Ca3P2 , etc. ), phosphoric acid ( H3PO4 ), sodium phosphate ( Na3PO4 ), hexafluorophosphoric acid ( HPF6 ), or the like.
• the phosphorus-containing molecule may be a fluorophosphine ( HgPFh ), where the sum of g and h is 3 or 5.
• the fluorophosphine examples include HPF2 and H2PF3 .
• the process gas may contain one or more of the above phosphorus-containing molecules as at least one phosphorus-containing molecule.
• the processing gas may contain at least one phosphorus-containing molecule selected from the group consisting of PF 3 , PCl 3 , PF 5 , PCl 5 , POCl 3 , PH 3 , PBr 3 , and PBr 5.
• the phosphorus-containing molecule contained in the processing gas is liquid or solid, the phosphorus-containing molecule may be vaporized by heating or the like and supplied into the plasma processing space 10s.
• the phosphorus-containing gas may be PCl a F b (a is an integer of 1 or more, b is an integer of 0 or more, and a+b is an integer of 5 or less) gas or PC c H d Fe (d and e are integers of 1 or more and 5 or less, and c is an integer of 0 or more and 9 or less) gas.
• the PCl a Fb gas may be, for example, at least one gas selected from the group consisting of PClF 2 gas, PCl 2 F gas, and PCl 2 F 3 gas.
• the PCcHdFe gas may be, for example, at least one gas selected from the group consisting of PF2CH3 gas, PF(CH3)2 gas, PH2CF3 gas , PH ( CF3 ) 2 gas , PCH3 ( CF3 ) 2 gas, PH2F gas, and PF3 ( CH3 ) 2 gas.
• the phosphorus-containing gas may be PCl c F d C e H f (c, d, e, and f are each an integer of 1 or more).
• the phosphorus-containing gas may be a gas containing P (phosphorus), F (fluorine), and a halogen other than F (fluorine) (e.g., Cl, Br, or I) in its molecular structure, a gas containing P (phosphorus), F (fluorine), C (carbon), and H (hydrogen) in its molecular structure, or a gas containing P (phosphorus), F (fluorine), and H (hydrogen) in its molecular structure.
• a gas containing P (phosphorus), F (fluorine), and H (hydrogen) in its molecular structure.
• the phosphorus-containing gas may be a phosphine-based gas, which may include phosphine (PH 3 ), a compound in which at least one hydrogen atom of phosphine is substituted with an appropriate substituent, and a phosphinic acid derivative.
• phosphine PH 3
• a compound in which at least one hydrogen atom of phosphine is substituted with an appropriate substituent and a phosphinic acid derivative.
• the substituents substituting the hydrogen atoms of the phosphine are not particularly limited, and examples thereof include halogen atoms such as fluorine atoms and chlorine atoms, alkyl groups such as methyl groups, ethyl groups, and propyl groups, and hydroxyalkyl groups such as hydroxymethyl groups, hydroxyethyl groups, and hydroxypropyl groups. Examples include chlorine atoms, methyl groups, and hydroxymethyl groups.
• Phosphinic acid derivatives include phosphinic acid (H 3 O 2 P), alkylphosphinic acids (PHO(OH)R), and dialkylphosphinic acids (PO(OH)R 2 ).
• phosphine-based gases include PCH3Cl2 ( dichloro (methyl)phosphine) gas, P( CH3 ) 2Cl (chloro(dimethyl)phosphine) gas, P( HOCH2 ) Cl2 (dichloro(hydroxylmethyl)phosphine) gas, P( HOCH2 ) 2Cl (chloro(dihydroxylmethyl)phosphine) gas, P( HOCH2 )( CH3 ) 2 (dimethyl(hydroxylmethyl)phosphine) gas, P( HOCH2 ) 2 ( CH3 )(methyl(dihydroxylmethyl)phosphine) gas, P( HOCH2 ) 3 (tris(hydroxylmethyl)phosphine) gas, H3O2P (phosphinic acid) gas, PHO(OH)( CH3 ) (methylphosphinic acid) gas, and PO(OH ) ( CH3 ) 2 At least one gas selected from the group consisting of (d
• the flow rate of the phosphorus-containing gas contained in the first processing gas may be 20 vol. % or less, 10 vol. % or less, or 5 vol. % or less of the total flow rate of the first processing gas excluding the flow rate of the inert gas.
• the first process gas may further include a tungsten-containing gas (W-containing gas).
• W-containing gas may be a gas containing tungsten and a halogen, and may be, for example, a WF x Cl y gas (x and y are integers from 0 to 6, and the sum of x and y is from 2 to 6).
• the tungsten-containing gas may be one or more of a gas containing tungsten and fluorine, such as tungsten difluoride (WF 2 ) gas, tungsten tetrafluoride (WF 4 ) gas, tungsten pentafluoride (WF 5 ) gas, and tungsten hexafluoride (WF 6 ) gas, and a gas containing tungsten and chlorine, such as tungsten dichloride (WCl 2 ) gas, tungsten tetrachloride (WCl 4 ) gas, tungsten pentachloride (WCl 5 ) gas, and tungsten hexachloride (WCl 6 ) gas.
• a gas containing tungsten and fluorine such as tungsten difluoride (WF 2 ) gas, tungsten tetrafluoride (WF 4 ) gas, tungsten pentafluoride (WF 5 ) gas, and tungsten hexafluoride
• the tungsten-containing gas may be at least one of WF6 gas and WCl6 gas.
• the first processing gas may contain a titanium-containing gas or a molybdenum-containing gas instead of or in addition to the tungsten-containing gas. That is, the first processing gas may contain at least one metal-containing gas.
• the at least one metal-containing gas may contain at least one metal selected from the group consisting of tungsten, molybdenum, titanium, and ruthenium.
• the first process gas may further include a halogen-containing gas.
• the first process gas may further include a halogen-containing gas other than fluorine, i.e., a halogen-containing gas that does not contain fluorine and/or a halogen-containing gas that contains fluorine.
• the halogen-containing gas other than fluorine may be a chlorine-containing gas, a bromine-containing gas, and/or an iodine-containing gas.
• the chlorine-containing gas may be at least one gas selected from the group consisting of Cl2 , SiCl2 , SiCl4 , CCl4 , SiH2Cl2 , Si2Cl6 , CHCl3 , SO2Cl2 , BCl3 , PCl3 , PCl5 , and POCl3 .
• the bromine-containing gas may be at least one gas selected from the group consisting of Br2 , HBr , CBr2F2 , C2F5Br , PBr3, PBr5 , POBr3 , and BBr3 .
• the iodine-containing gas may be at least one gas selected from the group consisting of HI , CF3I , C2F5I , C3F7I , IF5 , IF7 , I2 , and PI3 .
• the halogen-containing gas other than fluorine may be at least one gas selected from the group consisting of Cl2 gas, Br2 gas, and HBr gas.
• the halogen-containing gas other than fluorine is Cl2 gas or HBr gas.
• the fluorine-containing halogen-containing gas may also contain NF3 gas (nitrogen trifluoride gas) and/or SF6 gas (sulfur hexafluoride gas).
• the first process gas may further include an inert gas.
• the inert gas may be a noble gas such as Ar gas, He gas, Ne gas, Kr gas, Xe gas, or Rn gas, and/or nitrogen gas.
• the first processing gas may contain a gas capable of generating hydrogen fluoride species (HF species) in the first plasma, instead of a part or all of the HF gas.
• HF species includes at least one of hydrogen fluoride gas, radicals, and ions.
• the gas capable of generating HF species may be a single gas or a mixed gas containing fluorine and hydrogen.
• the single gas containing fluorine and hydrogen may be, for example, a hydrofluorocarbon gas.
• the hydrofluorocarbon gas may have a carbon number of 2 or more, 3 or more, or 4 or more.
• the hydrofluorocarbon gas is at least one selected from the group consisting of CH 2 F 2 gas, C 3 H 2 F 4 gas, C 3 H 2 F 6 gas, C 3 H 3 F 5 gas, C 4 H 2 F 6 gas, C 4 H 5 F 5 gas, C 4 H 2 F 8 gas, C 5 H 2 F 6 gas, C 5 H 2 F 10 gas, and C 5 H 3 F 7 gas.
• the hydrofluorocarbon gas is at least one selected from the group consisting of CH 2 F 2 gas, C 3 H 2 F 4 gas, C 3 H 2 F 6 gas, and C 4 H 2 F 6 gas.
• the hydrogen source in the mixed gas containing fluorine and hydrogen may be at least one selected from the group consisting of, for example, H2 gas, NH3 gas, H2O gas, H2O2 gas , and hydrocarbon gas ( CH4 gas, C3H6 gas, etc.).
• the fluorine source may be a fluorine-containing gas that does not contain carbon, such as, for example, NF3 gas, SF6 gas, WF6 gas, or XeF2 gas.
• the fluorine source may also be a fluorine-containing gas that contains carbon, such as a fluorocarbon gas and a hydrofluorocarbon gas.
• the fluorocarbon gas may be at least one selected from the group consisting of CF4 gas, C2F2 gas , C2F4 gas , C3F6 gas , C3F8 gas , C4F6 gas, C4F8 gas, and C5F8 gas.
• the hydrofluorocarbon gas may be at least one selected from the group consisting of CHF3 gas, CH2F2 gas , CH3F gas , C2HF5 gas, and hydrofluorocarbon gases containing three or more C's ( C3H2F4 gas , C3H2F6 gas, C4H2F6 gas, etc.) .
• the second etching step ST13 is performed following the first etching step ST12.
• the second etching step ST13 may be started before the recess RC reaches the underlayer UF. That is, the step ST13 may be started in a state where the silicon-containing film SF remains between the underlayer UF and the bottom of the recess RC, and may be performed during a period including the time when the underlayer UF is exposed. Alternatively, the second etching step ST13 may be started when at least a part of the underlayer UF is exposed in the recess.
• the switching from the step ST12 to the step ST13 may be performed based on at least one of the depth of the recess RC, the aspect ratio of the recess RC, and the etching time.
• step ST13 first, the second processing gas is supplied from the gas supply unit 20 into the plasma processing space 10s.
• step ST13 as in step ST12, a source RF signal is supplied to the lower electrode of the substrate support unit 11 and/or the upper electrode of the shower head 13. As a result, a high-frequency electric field is generated between the shower head 13 and the substrate support unit 11, and a second plasma is generated from the second processing gas in the plasma processing space 10s.
• a bias signal is supplied to the lower electrode of the substrate support unit 11, and a bias potential is generated between the plasma and the substrate W. The bias potential attracts active species such as ions and radicals in the plasma to the substrate W, and the silicon-containing film SF is further etched by the active species.
• Step ST13 is performed until the base film UF is exposed or until at least a part of the base film UF is etched in the depth direction.
• the temperature of the substrate support unit 11 may be maintained at the set temperature adjusted in step ST11, or may be changed as described later.
• FIG. 5 is a diagram showing an example of the cross-sectional structure of the substrate W at the end of process ST13.
• the bottom of the recess RC reaches the base film UF, exposing the base film UF.
• a portion of the base film UF may be etched in the depth direction.
• the aspect ratio of the recess RC in this state may be, for example, 20 or more, 30 or more, 40 or more, 50 or more, or 100 or more.
• the second processing gas may contain the same type of gas as the first processing gas, or may contain a different type of gas.
• the second processing gas may contain, for example, HF gas.
• the second processing gas may further contain, for example, at least one gas selected from the group consisting of the above-mentioned carbon-containing gas, oxygen-containing gas, and phosphorus-containing gas.
• the second processing gas may further contain, for example, the above-mentioned tungsten-containing gas, titanium-containing gas, and molybdenum-containing gas, an inert gas, and a halogen-containing gas.
• the second processing gas may contain, like the first processing gas, a gas capable of generating HF species in the second plasma instead of part or all of the HF gas.
• the source RF signal may have a frequency in the range of 10 MHz to 150 MHz. In one example, the source RF signal may have a frequency of 40 MHz or more or 60 MHz or more.
• the bias signal may be a bias RF signal supplied from the second RF generating unit 31b.
• the bias signal may also be a bias DC signal (e.g., a sequence of voltage pulses) supplied from the DC generating unit 32a.
• Both the source RF signal and the bias signal may be continuous waves or pulse waves, and one of the source RF signal and the bias signal may be a continuous wave and the other a pulse wave. When both the source RF signal and the bias signal are pulse waves, the periods of both pulse waves may be synchronized.
• the duty ratio of the pulse wave may be set appropriately, for example, 1 to 80%, or 5 to 50%.
• the duty ratio is the proportion of the period during which the power or voltage level is high in the pulse wave period.
• each voltage pulse in the sequence may have a rectangular, trapezoidal, triangular, or combination thereof.
• the polarity of each voltage pulse in the bias DC signal may be negative or positive, as long as the potential of the substrate W is set to provide a potential difference between the plasma and the substrate to attract ions.
• the supply of the source RF signal and/or bias signal may be performed continuously from step ST12.
• the supply of the source RF signal and/or bias signal may be stopped at the end of step ST12, and the supply of the source RF signal and/or bias signal may be started again at the start of step ST13.
• the etching process conditions (recipe 2) are changed from the process conditions (recipe 1) in process ST12. That is, in process ST13, etching of the silicon-containing film SF is performed with a recipe different from that in process ST12.
• the change in the recipe may include making the second process gas different from the first process gas, and/or performing temperature control to increase the temperature of the substrate W compared to process ST12.
• the process conditions (recipe 2) in process ST13 may be conditions that improve the selectivity of the silicon-containing film SF to the underlayer film UF compared to the process conditions (recipe 1) in process ST12.
• the process conditions (recipe 2) in process ST13 may be selected according to the film type of the underlayer film UF.
• the process conditions may be different when the underlayer film UF contains silicon and when it contains a metal.
• the change in the recipe may also include lowering the process pressure (pressure in the chamber during processing). That is, in step ST13, the pressure in the plasma processing space 10s may be reduced compared to step ST12. For example, the pressure in the plasma processing space 10s in step ST13 may be reduced by 30% or more compared to step ST12.
• FIG. 6 is an example of a timing chart in the case where the undercoat film UF contains silicon.
• the composition of the process gas is different between the process ST12 and the process ST13.
• the horizontal axis indicates time.
• the vertical axis indicates the flow rates of the HF gas, the carbon-containing gas, and the oxygen-containing gas contained in the process gas (first process gas or second process gas), and the density of the fluorine species in the plasma (first plasma or second plasma).
• “QL1", “QL2", and “QL3" indicate flow rates smaller than the flow rates indicated by "QH1", "QH2", and "QH3", or zero.
• the "carbon-containing gas” is one or both of a fluorocarbon gas and a hydrofluorocarbon gas.
• the flow rate of the carbon-containing gas is the sum of the flow rates of the fluorocarbon gas and the hydrofluorocarbon gas.
• fluorine species refers to active species of fluorine dissociated from a fluorine-containing gas (e.g., HF gas, fluorocarbon gas, hydrofluorocarbon gas, NF3 gas, SF6 gas, etc.) in the process gas.
• a fluorine-containing gas e.g., HF gas, fluorocarbon gas, hydrofluorocarbon gas, NF3 gas, SF6 gas, etc.
• the flow rate (partial pressure) of the HF gas may be decreased and the flow rates (partial pressures) of the carbon-containing gas (fluorocarbon gas and/or hydrofluorocarbon gas) and the oxygen-containing gas may be increased when switching from process ST12 to process ST13.
• the process gas (second process gas) may contain 50 volume % or more of the carbon-containing gas and the oxygen-containing gas with respect to the total flow rate of the second process gas excluding the flow rate of the inert gas.
• the carbon number of the fluorocarbon gas and/or hydrofluorocarbon gas contained in the second process gas may be 2 or more.
• the base film UF is exposed. If the base film UF contains silicon, the fluorine species in the plasma also function as an etchant for the base film UF.
• the density of the fluorine species in the second plasma generated in step ST13 is smaller than the density of the fluorine species in the first plasma generated in step ST12. Therefore, etching of the base film UF is suppressed. In other words, the etching selectivity of the silicon-containing film SF relative to the base film UF can be improved.
• FIG. 7 is another example of a timing chart in the case where the undercoat film UF contains silicon.
• FIG. 7 shows an example of control for increasing the temperature of the substrate W in step ST13 compared to the temperature of the substrate W in step ST12.
• the horizontal axis indicates time.
• the vertical axis indicates the signal level (power of the source RF signal and/or the level of the bias signal (absolute value of the power of the bias RF signal or the voltage level of the voltage pulse)), the DC voltage (ESC voltage) supplied to the electrostatic chuck 1111, the pressure of the heat transfer gas (e.g., He) supplied to the gap between the electrostatic chuck 1111 and the back surface of the substrate W, the temperature of the heater and/or the temperature of the heat transfer fluid flowing through the flow path 1110a (temperature control module temperature), and the temperature of the substrate W.
• "WL” indicates a signal level lower than the signal level indicated by "WH”.
• VL indicates an ESC voltage lower than the ESC voltage indicated by "VH”.
• PL indicates a pressure of the heat transfer gas lower than the pressure of the heat transfer gas indicated by "PH”.
• T1" and “TL2” indicate temperatures lower than the temperatures indicated by "TH1" and “TH2”, respectively.
• the signal level of the source RF signal and/or the signal level of the bias signal may be increased when switching from process ST12 to process ST13.
• Increasing the signal level may include increasing the effective value of the signal level (e.g., power), lengthening the signal supply time, and increasing the duty ratio of the signal. This increases the heat input to the substrate W, causing the temperature of the substrate W to rise.
• the DC voltage (ESC voltage) supplied to the electrostatic chuck 1111 may be reduced to reduce the chucking force of the electrostatic chuck 1111.
• the pressure of the heat transfer gas (e.g., He) between the electrostatic chuck 1111 and the rear surface of the substrate W may be reduced.
• the temperature of the heater and/or the temperature of the heat transfer fluid flowing through the flow path 1110a may be increased. In either case, the temperature of the substrate W increases. Note that one or more of the temperature controls (I) to (IV) may be combined.
• the difference between the temperature (TL2) of the substrate W in process ST12 and the temperature (TH2) of the substrate W in process ST13 may be, for example, 30° C. or more.
• the temperature (TL2) of the substrate W in process ST12 may be ⁇ 40° C.
• the temperature (TH2) of the substrate W in process ST13 may be 0° C.
• the base film UF is exposed.
• the temperature of the substrate W in step ST13 is higher than the temperature of the substrate W in step ST12. Therefore, the amount of etchant (e.g., fluorine species in the plasma) adsorbed to the base film UF is reduced. This suppresses etching of the base film UF, and the etching selectivity of the silicon-containing film SF to the base film UF can be improved.
• etchant e.g., fluorine species in the plasma
• both a change in the composition of the process gas for example, the change in the composition of the process gas described with reference to FIG. 6
• control to increase the temperature of the substrate W for example, the control described with reference to FIG. 7
• FIG. 8 is an example of a timing chart when the undercoat film UF contains metal.
• FIG. 8 shows an example when the composition of the process gas is different between the process ST12 and the process ST13.
• the horizontal axis indicates time.
• the vertical axis indicates the flow rates of HF gas, carbon-containing gas, and NF 3 /SF 6 gas contained in the process gas (first process gas or second process gas), and the density of fluorine species in the plasma (first plasma or second plasma).
• “QH1" and “QH2" each indicate a flow rate greater than 0.
• QL4" indicates a flow rate that is smaller than the flow rate indicated by "QH4" or is zero.
• DL indicates a density of fluorine species in the plasma that is smaller than the density of fluorine species in the plasma indicated by "DH".
• the "carbon-containing gas” is one or both of a fluorocarbon gas and a hydrofluorocarbon gas.
• the flow rate of the carbon-containing gas is the sum of the flow rates of the fluorocarbon gas and the hydrofluorocarbon gas.
• NF3 / SF6 gas is one or both of NF3 gas and SF6 gas.
• the flow rate of NF3 / SF6 gas is the sum of the flow rates of NF3 gas and SF6 gas.
• NF3 gas and SF6 gas are examples of fluorine sources that do not contain carbon and can be used in addition to the above-mentioned HF gas.
• the flow rate (partial pressure) of a fluorine-containing gas other than hydrogen fluoride for example, NF3 gas and/or SF6 gas, may be reduced when switching from process ST12 to process ST13.
• the flow rate (partial pressure) of HF gas may be reduced.
• the base film UF is exposed. If the base film UF contains a metal, the fluorine species in the plasma can react with the metal and etch the base film UF.
• the density of the fluorine species in the second plasma generated in step ST13 is smaller than the density of the fluorine species in the first plasma generated in step ST12. Therefore, etching of the base film UF is suppressed. In other words, the etching selectivity of the silicon-containing film SF relative to the base film UF can be improved.
• the temperature of the substrate W may be increased in step ST13.
• the temperature of the substrate W may be increased by combining one or more of the temperature controls (I) to (IV) described with reference to FIG. 7. This promotes the volatilization of by-products containing a metal contained in the undercoat film UF, and suppresses the generation of residues containing the metal.
• a gas having a high reactivity with the metal of the undercoat film UF may be added as the second process gas.
• CO gas may be added as the second process gas.
• the CO gas reacts with W scattered from the undercoat film UF during step ST13 to generate volatile W(CO) 6. This suppresses the generation of residues containing the metal (W) of the undercoat film UF.
• the second process gas may contain a chlorine-containing gas such as Cl 2 gas, SiCl 4 gas, or BCl 3 gas in addition to or instead of CO gas.
• etching of the silicon-containing film SF is performed under processing conditions (recipe) different from those in step ST12.
• This allows the optimum recipe to be selected depending on the progress of the etching, i.e., the depth of the recess RC. For example, in a region where the recess RC is shallow, a recipe that increases the etching rate of the silicon-containing film SF can be selected, and in a region where the recess RC is deep and the base film UF is exposed, a recipe that increases the etching selectivity of the silicon-containing film SF relative to the base film UF can be selected.
• Second Embodiment Fig. 9 is a flow chart showing the etching method according to the second embodiment.
• the etching method according to the second embodiment includes a step ST21 of providing a substrate, a step ST22 of generating plasma, and an etching step ST23.
• the processes in each of the steps ST21 to ST23 may be performed in the plasma processing system shown in Fig. 1. That is, the etching method according to the second embodiment may be performed using a plasma processing apparatus 1 as an etching apparatus.
• the etching method according to the second embodiment will be described by taking as an example a case where the control unit 2 controls each part of the plasma processing apparatus 1 to etch the substrate W.
• Step ST21 Providing a substrate
• the substrate W is provided in the plasma processing space 10s of the plasma processing apparatus 1.
• the substrate W is provided in the central region 111a of the substrate support 11.
• the substrate W is then held on the substrate support 11 by the electrostatic chuck 1111.
• the substrate W provided in step ST21 may be the same as the substrate W (see FIG. 3) described in relation to the first embodiment.
• the temperature of the substrate support part 11 is adjusted to a set temperature by a temperature control module, as in the first embodiment.
• the set temperature may be, for example, 20°C or less, 0°C or less, -10°C or less, -20°C or less, -30°C or less, -40°C or less, -50°C or less, -60°C or less, or -70°C or less.
• the temperature of the substrate support part 11 may be adjusted to the set temperature before step ST21. Furthermore, during the processing in steps ST22 and ST23, the temperature of the substrate support part 11 may be maintained at the set temperature adjusted in step ST21.
• Step ST22 Generation of plasma
• the processing gas is supplied into the plasma processing space 10s from the gas supply unit 20.
• the processing gas may be the same gas as the first processing gas and/or the second processing gas described in the first embodiment.
• a source RF signal is then supplied to the lower electrode of the substrate support 11 and/or the upper electrode of the shower head 13. This generates a high-frequency electric field between the shower head 13 and the substrate support 11, and generates plasma from the processing gas in the plasma processing space 10s.
• Fig. 10 is a diagram showing the relationship between ion flux and ion energy. As shown in Fig. 10, the higher the frequency of the source RF signal, the lower the ion energy. Also, the higher the frequency of the source RF signal, the greater the ion flux and the higher the electron density. For example, when a source RF signal (RF40) having a frequency of 40 MHz is used, when a source RF signal (RF60) having a frequency of 60 MHz is used, and when a source RF signal (RF100) having a frequency of 100 MHz is used, the following relationship is established for the ion energy and ion flux. Ion energy: RF40>RF60>RF100 Ion flux: RF40 ⁇ RF60 ⁇ RF100
• the frequency of the source RF signal is selected so that a high-density plasma is generated with low ion energy.
• a frequency may vary depending on the plasma generation method of the plasma processing apparatus.
• the frequency of the source RF signal may be 40 MHz or more.
• the frequency of the source RF signal supplied to the lower electrode of the substrate support portion 11 may be 60 MHz or more.
• the frequency of the source RF signal may be 150 MHz or less, or 100 MHz or less.
• a bias signal is supplied to the lower electrode of the substrate support 11. This generates a bias potential difference between the plasma and the substrate W.
• the bias potential difference attracts active species such as ions and radicals in the plasma to the substrate W.
• the bias signal may be a bias RF signal supplied from the second RF generator 31b.
• the bias signal may also be a bias DC signal (e.g., a sequence of voltage pulses) supplied from the DC generator 32a.
• each of the source RF signal and the bias signal may be a continuous wave or a pulse wave.
• one of the source RF signal and the bias signal may be a continuous wave and the other may be a pulse wave.
• the periods of both pulse waves may be synchronized.
• the duty ratio of the pulse wave may be set appropriately, for example, 1 to 80%, or 5 to 50%.
• the duty ratio is the proportion of the period during which the power or voltage level is high in the period of the pulse wave.
• each voltage pulse in the sequence may have a rectangular, trapezoidal, triangular, or combination thereof.
• the polarity of each voltage pulse in the bias DC signal may be negative or positive, as long as the potential of the substrate W is set so as to provide a potential difference between the plasma and the substrate to attract ions.
• FIG. 11 is a timing chart showing an example of a source RF signal and a bias RF signal.
• FIG. 11 shows an example in which the source RF signal and the bias RF signal are both pulse waves.
• the horizontal axis in FIG. 11 shows time.
• the source RF signal has a frequency of 40 MHz or more and 100 MHz or less.
• the source RF signal is supplied to the lower electrode of the substrate support 11 and/or the upper electrode of the shower head 13 in a first period and a second period alternating with the first period.
• the source RF signal has a first level (power level) in the first period and a second level (power level) in the second period.
• the first level is a power level lower than the second level or is 0 W.
• the bias RF signal is supplied to the lower electrode of the substrate support 11 in a third period and a fourth period alternating with the third period.
• the bias RF signal has a frequency of 400 kHz or more and 13.56 MHz or less.
• the bias RF signal has a third level (power level) in the third period and a fourth level (power level) in the fourth period.
• the third level is a power level lower than the fourth level or is 0 W.
• the second period and the fourth period may coincide (synchronize) with each other. Note that the second period and the fourth period may not overlap with each other in part or in whole.
• FIG. 12 is a timing chart showing an example of a source RF signal and a bias DC signal.
• FIG. 12 shows an example in which the source RF signal and the bias DC signal are both pulse waves.
• the horizontal axis of FIG. 12 shows time.
• the source RF signal shown in FIG. 12 is the same as the source RF signal in the example shown in FIG. 11.
• the bias DC signal is supplied to the lower electrode of the substrate support 11 in a fifth period and a sixth period that alternates with the fifth period.
• the bias DC signal has a fifth level (voltage level) in the fifth period and a sixth level (voltage level) in the sixth period.
• the absolute value of the fifth level is smaller than the absolute value of the sixth level or is 0V.
• the second period and the sixth period may coincide (synchronize). Note that the second period and the sixth period may not overlap each other partially or entirely.
• a second bias signal may be supplied to the upper electrode.
• the second bias signal may be a second DC signal supplied from the second DC generating unit 32b and/or a bias RF signal supplied from the second RF generating unit 31b.
• the second bias signal may be a continuous wave or a pulse wave.
• positive ions present in the plasma processing space 10s are attracted to the upper electrode and collide with the upper electrode, resulting in secondary electrons being emitted from the upper electrode.
• the emitted secondary electrons may modify the mask MF and improve the etching resistance of the mask MF.
• the charged state of the substrate W is neutralized by the irradiation of the secondary electrons, so that the linearity of the ions into the recesses of the silicon-containing film SF formed by etching is enhanced.
• the upper electrode is made of a silicon-containing material, the collision of the positive ions causes silicon to be emitted from the upper electrode together with the secondary electrons.
• the emitted silicon combines with oxygen in the plasma to become a silicon oxide compound.
• the silicon oxide compound can be deposited on the mask MF and function as a protective film.
• supplying the second bias signal to the upper electrode can have effects such as improving the selectivity, suppressing etching shape abnormalities, and improving the etching rate.
• Step ST23 Etching
• the silicon-containing film SF is etched by the plasma generated in the plasma processing space 10s, and a recess is formed in the silicon-containing film SF based on the shape of the opening OP of the mask MF.
• the etching is terminated.
• the frequency of the source RF signal is set to 40 MHz or more.
• the frequency of the source RF signal is 40 MHz or more, even if the power level of the source RF signal and/or the level of the bias signal (the power level of the bias RF signal or the voltage level of the bias DC signal) is increased to increase the electron density of the plasma, the increase in ion energy is suppressed.
• the frequency of the source RF signal is set to 40 MHz or more, it becomes possible to control the electron density of the generated plasma independently of the ion energy.
• step ST22 it is possible to suppress the increase in the ion energy of the plasma while generating a higher density plasma compared to when the frequency is lower than 40 MHz.
• the density of the etchant (HF species) is increased and the heat input to the substrate W is suppressed.
• the adsorption of the etchant (HF species) can also be promoted.
• the increase in ion energy is suppressed, so that damage to the mask MF can also be reduced. Therefore, according to the etching method of the second embodiment, the etching rate of the silicon-containing film SF can be improved, and the etching selectivity of the silicon-containing film SF relative to the mask MF can be improved.
• FIG. 13 is a flow chart showing an etching method according to the third embodiment.
• the etching method according to the third embodiment includes a step ST31 of providing a substrate, a first etching step ST32, and a second etching step ST33.
• the processes in each of the steps ST31 to ST33 may be performed in the plasma processing system shown in FIG. 1. That is, the etching method according to the third embodiment may be performed using a plasma processing apparatus 1 as an etching apparatus.
• the etching method according to the third embodiment will be described using, as an example, a case in which the control unit 2 controls each part of the plasma processing apparatus 1 to etch the substrate W. Note that the description of the parts of the third embodiment that overlap with those of the first or second embodiment will be omitted or simplified.
• Step ST31 Providing a substrate
• the substrate W is provided in the plasma processing space 10s of the plasma processing apparatus 1.
• the substrate W is provided in the central region 111a of the substrate support 11.
• the substrate W is then held on the substrate support 11 by the electrostatic chuck 1111.
• the substrate W provided in step ST31 may be the same as the substrate W (see FIG. 3) described in relation to the first embodiment.
• the temperature of the substrate support 11 is adjusted to a set temperature by the temperature control module.
• the set temperature may be, for example, 20°C or less, 0°C or less, -10°C or less, -20°C or less, -30°C or less, -40°C or less, -50°C or less, -60°C or less, or -70°C or less.
• adjusting or maintaining the temperature of the substrate support 11 includes setting the temperature of the heat transfer fluid flowing through the flow path 1110a and the heater temperature to their respective set temperatures, or to temperatures different from their respective set temperatures.
• the timing at which the heat transfer fluid starts to flow through the flow path 1110a may be before or after the substrate W is placed on the substrate support 11, or may be simultaneous with that time.
• the temperature of the substrate support 11 may also be adjusted to a set temperature before process ST31. That is, the substrate W may be provided to the substrate support 11 after the temperature of the substrate support 11 has been adjusted to the set temperature.
• Step ST32 First Etching Step
• the silicon-containing film SF is etched by using plasma generated from a first process gas.
• the first process gas is supplied into the plasma processing space 10s from the gas supply unit 20.
• the first process gas contains HF gas and a W-containing gas.
• a source RF signal is supplied to the lower electrode of the substrate support 11 and/or the upper electrode of the shower head 13.
• a high-frequency electric field is generated between the shower head 13 and the substrate support 11, and a first plasma is generated from the first processing gas in the plasma processing space 10s.
• a bias signal is also supplied to the lower electrode of the substrate support 11, and a bias potential difference is generated between the plasma and the substrate W.
• the bias potential difference attracts active species such as ions and radicals in the plasma to the substrate W.
• the silicon-containing film SF is etched, and a recess is formed in the silicon-containing film SF based on the shape of the opening OP of the mask MF.
• the first etching may be performed before (for example, just before) the base film UF is exposed, or until at least a part of the base film UF is exposed. That is, the process ST32 may be ended before (for example, just before) the base film UF of the substrate W is exposed, or at the timing when at least a part of the base film UF is exposed.
• FIG. 14 is a diagram showing an example of the cross-sectional structure of the substrate W at the end of step ST32.
• the processing in step ST32 etches the portion of the silicon-containing film SF exposed at the opening OP in the depth direction (from top to bottom in FIG. 14), forming a recess RC.
• FIG. 14 shows a state in which the base film UF is not exposed at the end of step ST32. That is, step ST32 may be stopped with the silicon-containing film SF remaining between the base film UF and the bottom of the recess RC, and step ST33 may be started in this state and performed during a period that includes the time when the base film UF is exposed. Alternatively, at least a portion of the base film UF may be exposed in the recess RC at the end of step ST32.
• a first convex portion CV1 is formed on the sidewall of the mask MF at a first position on the mask MF near the top of the opening OP.
• the first convex portion reduces the width of the opening OP of the mask MF.
• the first convex portion CV1 is thought to be formed by deposition of a deposit component contained in the first process gas and/or a reaction by-product generated by etching at the first position.
• the first convex portion CV1 can be formed from a carbon-containing material derived from a carbon-containing gas described below.
• a second convex portion CV2 that reduces the width of the opening OP is formed at a second position on the sidewall of the mask MF.
• the second position is a position lower than the first position.
• the second convex portion CV2 is formed of a W-containing material (or a metal-containing material) derived from a W-containing gas (or a metal-containing gas). The second convex portion CV2 suppresses the incidence of ions on the sidewall of the recess RC and the incidence of ions on the bottom of the recess RC.
• the phenomenon in which the silicon-containing film SF is etched in the horizontal direction is suppressed.
• the shape of the recess RC shape in vertical cross section
• becomes a shape that tapers toward the bottom reverse tapered shape
• the amount of hydrogen species and the amount of fluorine species in the first plasma may be adjusted in step ST32 so as to form the second protrusion CV2 below the first protrusion CV1.
• the flow rate of the hydrogen source gas, which is a source of hydrogen species in the first processing gas, and the flow rate of the fluorine source gas, which is a source of fluorine species in the first processing gas may be adjusted.
• the fluorine species reduces the amount of W-containing material (or metal-containing material) near the upper end of the opening OP of the mask MF.
• the hydrogen species reduces the amount of fluorine species. Therefore, the higher the ratio of the amount of fluorine species to the amount of hydrogen species, the lower the second position becomes. Therefore, by adjusting the amount of fluorine species and the amount of hydrogen species, it is possible to adjust the second position where the second protrusion CV2 is formed.
• the HF gas contained in the first process gas may have the largest flow rate among the first process gas (if the first process gas contains an inert gas, all gases in the first process gas excluding the inert gas).
• the flow rate of the HF gas may be adjusted within the same range as the flow rate of the HF gas in the first embodiment.
• the tungsten-containing gas (W-containing gas) contained in the first processing gas may be a gas containing tungsten and a halogen, and may be, for example, a WF x Cl y gas (x and y are integers from 0 to 6, and the sum of x and y is from 2 to 6).
• the W-containing gas may be one or more of a gas containing tungsten and fluorine, such as tungsten difluoride (WF 2 ) gas, tungsten tetrafluoride (WF 4 ) gas, tungsten pentafluoride (WF 5 ) gas, or tungsten hexafluoride (WF 6 ) gas, or a gas containing tungsten and chlorine, such as tungsten dichloride (WCl 2 ) gas, tungsten tetrachloride (WCl 4 ) gas, tungsten pentachloride (WCl 5 ) gas, or tungsten hexachloride (WCl 6 ) gas.
• a gas containing tungsten and fluorine such as tungsten difluoride (WF 2 ) gas, tungsten tetrafluoride (WF 4 ) gas, tungsten pentafluoride (WF 5 ) gas, or tungsten hexafluoride (W
• the W-containing gas may be at least one of WF6 gas and WCl6 gas.
• the first processing gas may contain one or more of a molybdenum-containing gas, a titanium-containing gas, and a ruthenium-containing gas instead of or in addition to the W-containing gas. That is, the first processing gas may contain at least one metal-containing gas selected from the group consisting of a tungsten-containing gas, a molybdenum-containing gas, a titanium-containing gas, and a ruthenium-containing gas. In other words, the first processing gas may contain at least one metal-containing gas.
• the at least one metal-containing gas may contain at least one metal selected from the group consisting of tungsten, molybdenum, titanium, and ruthenium.
• the first processing gas may further include a phosphorus-containing gas.
• the first processing gas may further include a carbon-containing gas.
• the first processing gas may further include an oxygen-containing gas.
• the first processing gas may further include a halogen-containing gas.
• the first processing gas may include a halogen-containing gas other than fluorine, i.e., a fluorine-free halogen-containing gas and/or a fluorine-containing halogen-containing gas.
• the first processing gas includes a phosphorus-containing gas, a carbon-containing gas, and a halogen-containing gas in addition to HF gas and W-containing gas.
• the phosphorus-containing gas, carbon-containing gas, oxygen-containing gas, and halogen-containing gas that the first processing gas may include may be the gases corresponding to those listed in the description of the first embodiment.
• the first process gas may further contain a halogen-containing gas, similar to the first process gas in the first embodiment.
• the halogen-containing gas may contain NF3 gas.
• the first process gas may contain one or more other halogen-containing gases instead of or in addition to NF3 gas.
• the first process gas may further contain Cl2 gas and HBr gas instead of or in addition to NF3 gas.
• the first process gas may not contain at least one noble gas, or may contain a noble gas at a flow rate lower than the flow rate of the noble gas in the second process gas described below.
• the first process gas may contain a first noble gas and/or a second noble gas as the noble gas.
• the first noble gas includes at least one noble gas selected from the group consisting of krypton (Kr) gas, xenon (Xe) gas, and radon (Rn) gas.
• the second noble gas includes at least one noble gas selected from the group consisting of Ar, Ne, and He.
• the first processing gas may contain a gas capable of generating hydrogen fluoride species (HF species) in the first plasma, instead of a part or all of the HF gas.
• HF species includes at least one of hydrogen fluoride gas, radicals, and ions.
• the gas capable of generating HF species may be a single gas or a mixed gas containing fluorine and hydrogen. As the single gas or the mixed gas containing fluorine and hydrogen, the gases listed in the description of the first embodiment above can be used.
• Step ST33 is performed following step ST32.
• step ST33 may be started before the recess RC reaches the undercoat film UF. That is, step ST33 may be started in a state in which the silicon-containing film SF remains between the undercoat film UF and the bottom of the recess RC. Alternatively, step ST33 may be started when at least a part of the undercoat film UF is exposed in the recess RC. Switching from step ST32 to step ST33 may be performed based on at least one of the depth of the recess RC, the aspect ratio of the recess RC, and the etching time.
• step ST33 first, the second processing gas is supplied from the gas supply unit 20 into the plasma processing space 10s.
• step ST33 as in step ST12, a source RF signal is supplied to the lower electrode of the substrate support unit 11 and/or the upper electrode of the shower head 13. As a result, a high-frequency electric field is generated between the shower head 13 and the substrate support unit 11, and a second plasma is generated from the second processing gas in the plasma processing space 10s.
• a bias signal is supplied to the lower electrode of the substrate support unit 11, and a bias potential difference is generated between the plasma and the substrate W. The bias potential difference attracts active species such as ions and radicals in the plasma to the substrate W, and the silicon-containing film SF is further etched by the active species.
• Step ST33 is performed until the base film UF is exposed or until a part of the base film UF is etched in the depth direction.
• the temperature of the substrate support unit 11 may be maintained at the set temperature adjusted in step ST31, or may be changed.
• FIG. 15 is a diagram showing an example of the cross-sectional structure of the substrate W during processing in step ST33.
• the bottom of the recess RC reaches the base film UF, and the base film UF is exposed in the recess RC.
• a part of the base film UF may be etched in the depth direction.
• the opening width of the bottom of the recess RC can be enlarged by the plasma generated from the second processing gas, and the shape of the recess RC (shape in vertical cross section) can be made rectangular.
• the aspect ratio of the recess RC in this state may be, for example, 20 or more, or may be 30 or more, 40 or more, 50 or more, or 100 or more.
• the HF gas contained in the second process gas may have the largest flow rate (partial pressure) among the second process gas (if the second process gas contains an inert gas, among all gases in the second process gas excluding the inert gas).
• the flow rate of the HF gas may be adjusted within the same range as the flow rate of the HF gas in the first embodiment.
• the second process gas may include at least one noble gas.
• the second process gas may include the above-mentioned first noble gas and/or second noble gas as the at least one noble gas.
• the second process gas may include nitrogen gas.
• the second process gas may contain a halogen-containing gas, similar to the first process gas.
• the second process gas may contain a carbon-containing gas, similar to the first process gas.
• the second process gas may not contain a W-containing gas (or a metal-containing gas), or may contain a W-containing gas at a flow rate less than the flow rate of the W-containing gas (or metal-containing gas) in the first process gas. In one example, the second process gas does not contain a W-containing gas (or a metal-containing gas). Note that when the second process gas contains a W-containing gas (or a metal-containing gas), the W-containing gas (or metal-containing gas) may be any of the W-containing gases (or metal-containing gases) described above.
• the second process gas may not contain a phosphorus-containing gas or may contain a phosphorus-containing gas at a flow rate less than the flow rate of the phosphorus-containing gas in the first process gas. In one example, the second process gas does not contain a phosphorus-containing gas. Note that if the second process gas contains a phosphorus-containing gas, the phosphorus-containing gas may be any of the phosphorus-containing gases described above.
• FIG. 16 is an example of a timing chart of the third embodiment.
• the horizontal axis indicates time.
• the vertical axis indicates the flow rates of the HF gas, W-containing gas, first noble gas, and phosphorus-containing gas contained in the process gas (first process gas or second process gas).
• "QH1", “QH2", “QH3”, and “QH4" are each flow rates greater than 0.
• "QL1", “QL2", “QL3”, and “QL4" indicate flow rates smaller than "QH1", “QH2", “QH3", and "QH4", or zero, respectively.
• the flow rate (partial pressure) of the W-containing gas (or metal-containing gas) and/or the flow rate of the phosphorus-containing gas may be decreased, and the flow rate (partial pressure) of the first noble gas may be increased.
• step ST32 the silicon-containing film SF is etched by a first process gas containing HF gas and a W-containing gas (or a metal-containing gas).
• step ST33 the silicon-containing film SF is further etched by a second process gas containing HF gas.
• step ST32 a second convex portion CV2 is formed on the side wall of the mask MF, thereby suppressing the occurrence of bowing in the silicon-containing film SF.
• the shape (shape in the vertical cross section) of the recess RC formed in step ST32 is inversely tapered, but the opening width of the bottom of the recess RC can be enlarged by step ST33 to make the shape of the recess RC rectangular.
• the enlargement of the opening width of the bottom of the recess RC in step ST33 is partly achieved by using a second process gas in which the flow rate of the W-containing gas (or metal-containing gas) is reduced or set to zero.
• step ST32 is switched to step ST33 before the recess RC reaches the base film UF or when at least a portion of the base film UF is exposed.
• the timing of switching from step ST32 to step ST33 is not limited to this.
• step ST32 may be switched to step ST33 after the recess RC reaches the base film UF and a portion of the base film UF is etched.
• a cycle including steps ST32 and ST33 may be performed multiple times until the base film UF is exposed or a portion of the base film UF is etched.
• the first processing gas may further contain a phosphorus-containing gas.
• the second processing gas may not contain a phosphorus-containing gas or may contain a phosphorus-containing gas at a flow rate lower than the flow rate of the phosphorus-containing gas in the first processing gas.
• the phosphorus-containing gas increases the etching rate of the silicon-containing film SF at the bottom of the recess RC and suppresses lateral etching of the sidewalls defining the recess RC. Therefore, when the first processing gas contains a phosphorus-containing gas, the etching rate of the silicon-containing film SF can be increased and bowing can be suppressed.
• step ST32 may be stopped with the silicon-containing film SF remaining between the base film UF and the bottom of the recess RC, and step ST33 may be started in this state.
• the second process gas may further include the above-mentioned first noble gas (e.g., xenon gas).
• the first process gas may not include the first noble gas, or may include the first noble gas at a flow rate lower than the flow rate of the first noble gas in the second process gas.
• the first process gas and the second process gas may further include a halogen-containing gas.
• the halogen-containing gas may include NF3 gas.
• the halogen-containing gas may further include one or more other halogen-containing gases such as Cl2 gas and/or HBr gas.
• the first process gas may further include a halogen-containing gas including NF3 gas.
• the halogen-containing gas may further include one or more other halogen-containing gases such as Cl2 gas and/or HBr gas in addition to NF3 gas.
• the second process gas may also include a halogen-containing gas like the first process gas.
• the second process gas may not include NF3 gas, or may include NF3 gas at a flow rate less than the flow rate of NF3 gas in the first process gas.
• the second process gas may further include an oxygen-containing gas (e.g., O2 gas) and a noble gas.
• the first process gas may not include a noble gas, or may include a noble gas at a flow rate less than the flow rate of the noble gas in the second process gas.
• the noble gas of each of the first process gas and the second process gas may be a first noble gas (e.g., xenon gas), a second noble gas (e.g., argon gas), or may include both the first noble gas and the second noble gas.
• the etching method of the first embodiment may be used in combination with the etching method of the second embodiment and/or the etching method of the third embodiment.
• the etching method of the second embodiment may be used in combination with the etching method of the third embodiment.
• the etching methods of the respective embodiments may be performed using a plasma processing apparatus using any plasma source, such as inductively coupled plasma or microwave plasma, other than the capacitively coupled plasma processing apparatus 1.
• a metal-containing gas such as the W-containing gas described above is included in the process gas (e.g., the first process gas) as a metal supply source.
• the metal supply source may be an upper electrode formed from a metal-containing material and/or an edge ring made of a metal-containing material. That is, the metal-containing material released from the upper electrode and/or the edge ring in the first etching step may form the second protrusion CV2.
• the first processing gas and the second processing gas do not have to contain a metal-containing gas such as the W-containing gas described above. Furthermore, in the etching methods according to the various embodiments described above, a metal supply source does not have to be used.
• the film to be etched may be a film other than the silicon-containing film SF.
• (Appendix 1) An etching method performed in a plasma processing apparatus having a chamber, comprising: (a) providing a substrate having an underlayer and a silicon-containing film on the underlayer in a chamber; (b) etching the silicon-containing film using a first plasma generated from a first process gas containing hydrogen fluoride gas to form a recess, the etching being performed before the base film is exposed in the recess or until at least a portion of the base film is exposed in the recess; (c) further etching the silicon-containing film in the recess under conditions different from those of (b); and An etching method comprising:
• (Appendix 4) 4. The etching method according to claim 2, wherein the undercoat film contains silicon, and the second process gas contains a fluorocarbon gas or a hydrofluorocarbon gas and an oxygen-containing gas in an amount of 50 volume % or more with respect to a total flow rate of the second process gas excluding a flow rate of an inert gas.
• the temperature control includes one or more of: (I) increasing the power of a source RF signal or a bias signal supplied to the chamber; (II) decreasing an adhesive force of a substrate support that supports the substrate; (III) decreasing a pressure of a heat transfer gas supplied to a gap between the substrate and the substrate support; and (IV) setting a temperature of the substrate support higher than the temperature set in step (b).
• An etching method performed in a plasma processing apparatus having a chamber comprising: (a) providing a substrate having an underlayer and a silicon-containing film on the underlayer in a chamber; (b) etching the silicon-containing film using a plasma including an HF species to form a recess, the etching being performed before the underlying film is exposed in the recess or until at least a portion of the underlying film is exposed in the recess; (c) further etching the silicon-containing film in the recess under conditions different from those in the step (b).
• a plasma processing apparatus having a chamber and a control unit, The control unit is (a) controlling a substrate having an underlayer and a silicon-containing film on the underlayer in the chamber; (b) controlling a process for etching the silicon-containing film using a first plasma generated from a first process gas containing hydrogen fluoride gas to form a recess, the process being performed before the base film is exposed in the recess or until at least a portion of the base film is exposed in the recess; (c) controlling to further etch the silicon-containing film in the recess under conditions different from those in the control of (b); and 13.
• a plasma processing system configured to perform the steps of:
• a device manufacturing method carried out in a plasma processing apparatus having a chamber comprising: (a) providing a substrate having an underlayer and a silicon-containing film on the underlayer in a chamber; (b) etching the silicon-containing film using a first plasma generated from a first process gas containing hydrogen fluoride gas to form a recess, the etching being performed before the base film is exposed in the recess or until at least a portion of the base film is exposed in the recess; (c) further etching the silicon-containing film in the recess under conditions different from those of (b); and A device manufacturing method comprising:
• a computer of a plasma processing system including a plasma processing apparatus having a chamber and a control unit, (a) controlling a substrate having an undercoat film and a silicon-containing film on the undercoat film to be provided to the chamber; (b) controlling a process for etching the silicon-containing film using a first plasma generated from a first process gas containing hydrogen fluoride gas to form a recess, the process being performed before the base film is exposed in the recess or until at least a portion of the base film is exposed in the recess; (c) controlling to further etch the silicon-containing film in the recess under conditions different from the control of (b); and A program that executes the following.
• An etching method performed in a plasma processing apparatus having a chamber comprising: (a) providing a substrate having a silicon-containing film in a chamber; (b) supplying a process gas containing hydrogen fluoride gas into the chamber and generating a plasma from the process gas by supplying an RF signal having a frequency of 40 MHz or more to the chamber; (c) etching the silicon-containing film using the plasma.
• An etching method performed in a plasma processing apparatus having a chamber comprising: (a) providing a substrate having a silicon-containing film in a chamber; (b) supplying a process gas into the chamber and providing an RF signal having a frequency of 40 MHz or greater to the chamber to generate a plasma from the process gas that includes HF species; (c) etching the silicon-containing film using the plasma.
• a plasma processing apparatus having a chamber and a control unit, The control unit is (a) controlling providing a substrate having a silicon-containing film in a chamber; (b) supplying a process gas containing hydrogen fluoride gas into the chamber and supplying an RF signal having a frequency of 40 MHz or more to the chamber to generate plasma from the process gas; (c) controlling etching of the silicon-containing film using the plasma; and 13.
• a plasma processing system configured to perform the steps of:
• a device manufacturing method carried out in a plasma processing apparatus having a chamber comprising: (a) providing a substrate having a silicon-containing film in a chamber; (b) supplying a process gas containing hydrogen fluoride gas into the chamber and generating a plasma from the process gas by supplying an RF signal having a frequency of 40 MHz or more to the chamber; (c) etching the silicon-containing film using the plasma.
• a computer of a plasma processing system including a plasma processing apparatus having a chamber and a control unit, (a) controlling providing a substrate having a silicon-containing film in a chamber; (b) supplying a process gas containing hydrogen fluoride gas into the chamber and supplying an RF signal having a frequency of 40 MHz or more to the chamber to generate plasma from the process gas; (c) controlling etching of the silicon-containing film using the plasma; and A program that executes the following.
• (Appendix A1) (a) providing a substrate having an underlayer, a silicon-containing film on the underlayer, and a mask on the silicon-containing film in a chamber; (b) etching the silicon-containing film using a first plasma generated from a first process gas including hydrogen fluoride gas and a tungsten-containing gas to form a recess; (c) after the step (b), further etching the silicon-containing film using a second plasma generated from a second process gas including hydrogen fluoride gas; Including, The second process gas does not contain the tungsten-containing gas or contains the tungsten-containing gas at a flow rate lower than a flow rate of the tungsten-containing gas in the first process gas. Etching method.
• Appendix A4 The etching method according to Appendix A4, wherein the second process gas does not contain a phosphorus-containing gas or contains a phosphorus-containing gas at a flow rate lower than a flow rate of the phosphorus-containing gas in the first process gas.
• Appendix A6 The etching method according to any one of appendices A1 to A5, wherein the second process gas further contains xenon gas.
• Appendix A7 The etching method according to Appendix A6, wherein the first process gas does not contain a xenon gas or contains a xenon gas at a flow rate lower than a flow rate of the xenon gas in the second process gas.
• the first process gas includes nitrogen trifluoride gas; the second process gas does not contain nitrogen trifluoride gas or contains nitrogen trifluoride gas at a flow rate less than a flow rate of the nitrogen trifluoride gas in the first process gas; the second process gas further comprises an oxygen-containing gas and a noble gas; the first process gas does not contain a noble gas or contains a noble gas at a flow rate less than the flow rate of the noble gas in the second process gas;
• the etching method according to A4 or A5.
• Appendix A10 The etching method according to any one of Appendices A1 to A9, wherein the step (b) is performed before the base film is exposed in the recess or until at least a part of the base film is exposed in the recess.
• Appendix A12 The etching method according to any one of Appendices A1 to A9, wherein a cycle including the step (b) and the step (c) is performed a plurality of times.
• the first process gas further includes a carbon-containing gas that is a source of the first protrusion; the tungsten-containing gas in the first process gas is a source of the second protrusion; In the step (b), an amount of hydrogen species and an amount of fluorine species in the first plasma are adjusted so as to form the second convex portion below the first convex portion.
• (Appendix A16) (a) providing a substrate having an underlayer, a silicon-containing film on the underlayer, and a mask on the silicon-containing film in a chamber; (b) etching the silicon-containing film with a first plasma generated from a first process gas to form a recess; (c) after the step (b), further etching the silicon-containing film using a second plasma generated from a second process gas;
• the first process gas includes a single gas or a mixed gas including fluorine and hydrogen, and a metal-containing gas
• the second process gas comprises a single gas or a mixture of gases including fluorine and hydrogen;
• the second process gas does not contain the metal-containing gas or contains the metal-containing gas at a flow rate lower than a flow rate of the metal-containing gas in the first process gas.
• Appendix A17 The etching method according to Appendix A16, wherein the metal-containing gas contains at least one metal selected from the group consisting of tungsten, molybdenum, titanium, and ruthenium.
• Appendix A19 The etching method according to Appendix A18, wherein the second process gas does not contain a phosphorus-containing gas or contains a phosphorus-containing gas at a flow rate lower than a flow rate of the phosphorus-containing gas in the first process gas.
• Appendix A21 The etching method according to any one of Appendix A16 to A20, wherein the second process gas further contains a noble gas.
• Appendix A22 The etching method according to Appendix A21, wherein the first process gas does not contain the noble gas or contains the noble gas at a flow rate lower than a flow rate of the noble gas in the second process gas.
• Appendix A23 The etching method according to appendix A21 or A22, wherein the noble gas includes at least one selected from the group consisting of argon gas, krypton gas, xenon gas, and radon gas.
• the first process gas includes nitrogen trifluoride gas; the second process gas does not contain nitrogen trifluoride gas or contains nitrogen trifluoride gas at a flow rate less than a flow rate of the nitrogen trifluoride gas in the first process gas; the second process gas further comprises an oxygen-containing gas and a noble gas; the first process gas does not contain a noble gas or contains a noble gas at a flow rate less than the flow rate of the noble gas in the second process gas; An etching method according to appendix A19 or A20.
• step (Appendix A26) The etching method according to any one of Additions A16 to A25, wherein the step (b) etches the silicon-containing film while forming a first convex portion at a first position of the mask, the first convex portion reducing a width of an opening of the mask, and forming a second convex portion at a second position of the mask lower than the first position, the second convex portion reducing a width of the opening of the mask.
• the first process gas further includes a carbon-containing gas that is a source of the first protrusion; the metal-containing gas in the first process gas is a source of the second protrusion; In the step (b), an amount of hydrogen species and an amount of fluorine species in the first plasma are adjusted so as to form the second convex portion below the first convex portion.
• the control unit is (a) providing a substrate having an underlayer, a silicon-containing film on the underlayer, and a mask on the silicon-containing film in the chamber; (b) etching the silicon-containing film using a first plasma generated from a first process gas including a hydrogen fluoride gas and a tungsten-containing gas to form a recess; (c) after the step (b), further etching the silicon-containing film using a second plasma generated from a second process gas containing hydrogen fluoride gas, the second process gas not containing the tungsten-containing gas or containing the tungsten-containing gas at a flow rate lower than a flow rate of the tungsten-containing gas in the first process gas; 23.
• An etching apparatus configured to perform a process including:
• Appendix A31 The etching apparatus of Appendix A30, wherein the second process gas does not contain a phosphorus-containing gas or contains a phosphorus-containing gas at a flow rate lower than a flow rate of the phosphorus-containing gas in the first process gas.
• the control unit is the etching of the silicon-containing film in step (b) is stopped in a state where the silicon-containing film is left between the base film and a bottom of the recess;
• the etching of the silicon-containing film in (c) is started in the above state and is performed for a period including the time when the base film is exposed.
• the etching apparatus of claim A31 configured as follows.
• Appendix A34 The etching apparatus according to Appendix A33, wherein the first process gas does not contain xenon gas, or contains xenon gas at a flow rate lower than a flow rate of the xenon gas in the second process gas.
• Appendix A35 The etching apparatus of Appendix A34, wherein each of the first process gas and the second process gas contains nitrogen trifluoride gas.
• the first process gas includes nitrogen trifluoride gas; the second process gas does not contain nitrogen trifluoride gas or contains nitrogen trifluoride gas at a flow rate less than a flow rate of the nitrogen trifluoride gas in the first process gas; the second process gas further comprises an oxygen-containing gas and a noble gas; the first process gas does not contain a noble gas or contains a noble gas at a flow rate less than the flow rate of the noble gas in the second process gas;
• the etching apparatus according to appendix A31 or A32.
• the first process gas further includes a carbon-containing gas that is a source for forming a first protrusion at a first position of the mask that reduces a width of an opening of the mask;
• the tungsten-containing gas in the first process gas is a source for forming a second protrusion at a second position of the mask that is lower than the first position, the second protrusion reducing a width of the opening of the mask;
• the control unit is configured to adjust an amount of hydrogen species and an amount of fluorine species in the first plasma in order to form the second convex portion below the first convex portion in (b).
• An etching apparatus according to any one of appendices A28 to A36.
• Appendix A38 a gas supply configured to supply the first process gas and the second process gas into the chamber;
• the control unit is configured to further control the gas supply unit.
• the control unit is (a) providing a substrate having a film to be etched and a mask on the film to be etched in the chamber; (b) etching the film to be etched using plasma generated from a process gas containing hydrogen fluoride gas to form a recess; and performing the process (b) in a state where a metal supply source is present in the chamber to form a first convex portion at a first position of the mask, the first convex portion reducing a width of the opening of the mask, and to form a second convex portion at a second position of the mask lower than the first position, the second convex portion reducing a width of the opening of the mask, while etching the etching target film.
• Etching equipment is (a) providing a substrate having a film to be etched and a mask on the film to be etched in the chamber; (b) etching the film to be etched using plasma generated from a process gas containing hydrogen fluoride gas to form a recess; and performing the
• the process gas further comprises a metal-containing gas; the metal source is the metal-containing gas;
• Appendix A41 An etching apparatus as described in Appendix A39, wherein the metal supply source is formed from a metal-containing material and is an upper electrode arranged above the substrate support to face the substrate support and/or an edge ring made of a metal-containing material arranged around the substrate supported by the substrate support.
• the plasma processing apparatus 1 was used to etch the silicon-containing film of the sample substrate.
• the sample substrate had a multilayer film as a silicon-containing film on an undercoat film, and had a mask formed of amorphous carbon on the multilayer film.
• the multilayer film included a plurality of silicon oxide films and a plurality of silicon nitride films that were alternately stacked.
• the etching in the first and second experimental examples included a first etching step and a second etching step following the first etching step.
• a mixed gas containing HF gas, PF3 gas, and a halogen-containing gas was used as the first processing gas in the first etching step.
• the halogen-containing gas contained NF3 gas, Cl2 gas, and HBr gas.
• a mixed gas that was the same as the first processing gas except that it did not contain PF3 gas was used as the second processing gas in the second etching step.
• a mixed gas that was the same as the first processing gas in the first experimental example was used as the first processing gas in the first etching step and the second processing gas in the second etching step.
• the first etching step was stopped when the silicon-containing film was left between the undercoat film and the bottom of the recess, and the second etching step was started in this state.
• the maximum width of the recess formed in the silicon-containing film i.e., bowing CD
• the width at the bottom of the recess i.e., bottom CD
• the difference between the bowing CD and the bottom CD i.e., the CD bias, was obtained.
• the bowing CD of the first experimental example was approximately equal to the bowing CD of the second experimental example
• the bottom CD of the first experimental example was approximately 11 nm larger than the bottom CD of the second experimental example.
• the CD bias of the second experimental example was 47.6 nm
• the CD bias of the first experimental example was 35.2 nm.
• the plasma processing apparatus 1 was used to etch the silicon-containing film of the same sample substrate as in the first experimental example.
• the etching in the third to fifth experimental examples included a first etching step and a second etching step following the first etching step.
• a mixed gas containing HF gas, WF 6 gas, PF 3 gas, a halogen-containing gas, and a carbon-containing gas was used as the first processing gas in the first etching step.
• the halogen-containing gas contained NF 3 gas, Cl 2 gas, and HBr gas.
• the carbon-containing gas contained a hydrofluorocarbon gas.
• a mixed gas containing the same as the first processing gas in the third experimental example was used as the second processing gas in the second etching step, except that it did not contain WF 6 gas and PF 3 gas.
• the second process gas in the second etching step was the same mixed gas as the first process gas in the fourth experimental example, except that it did not contain WF6 gas and PF3 gas, and further contained xenon gas.
• the first process gas in the first etching step was the same mixed gas as the first process gas in the third experimental example, except that it did not contain WF6 gas.
• the second process gas in the second etching step was the same mixed gas as the second process gas in the third experimental example.
• the first etching step was stopped in a state where the silicon-containing film was left between the base film and the bottom of the recess, and the second etching step was started in this state.
• the maximum width of the recess formed in the silicon-containing film i.e., bowing CD
• the width at the bottom of the recess i.e., bottom CD
• the difference between the bowing CD and the bottom CD i.e., the CD bias
• the bowing CDs of the third and fourth experimental examples were about 7 nm smaller than the bowing CD of the fifth experimental example. From this result, it was confirmed that it is possible to suppress bowing by using a first processing gas containing a metal-containing gas such as WF 6 gas.
• the bottom CD in the third experimental example was approximately the same as the bottom CD in the fifth experimental example, but the bottom CD in the fourth experimental example was about 5 nm larger than the bottom CD in the fifth experimental example. From this, it was confirmed that it is possible to obtain a relatively large bottom CD by using a second processing gas containing a first noble gas such as xenon gas.
• the CD bias in the fifth experimental example was 37.6 nm, whereas the bottom CD in the third experimental example was 33.7 nm and the bottom CD in the fourth experimental example was 25.9 nm.
• the plasma processing apparatus 1 was used to etch the silicon-containing film of the same sample substrate as in the first experimental example.
• the etching in the sixth and seventh experimental examples included a first etching step and a second etching step following the first etching step.
• a mixed gas containing HF gas, PF3 gas, a halogen-containing gas, and a carbon-containing gas was used as the first processing gas in the first etching step.
• the halogen-containing gas included NF3 gas, Cl2 gas, and HBr gas.
• the carbon-containing gas included a fluorocarbon gas.
• a mixed gas containing a noble gas in addition to all the gases in the first processing gas in each experimental example was used as the second processing gas in the second etching step.
• the noble gas was xenon gas
• the noble gas was argon gas.
• the first etching step was stopped in a state where the silicon-containing film was left between the undercoat film and the bottom of the recess, and in this state, the second etching step was started.
• the maximum width of the recess formed in the silicon-containing film i.e., bowing CD
• the width at the bottom of the recess i.e., bottom CD
• the difference between the bowing CD and the bottom CD i.e., the CD bias
• the bowing CDs in the sixth and seventh experimental examples were approximately the same.
• the bottom CD in the sixth experimental example was 29 nm larger than the bottom CD in the seventh experimental example.
• the CD bias in the seventh experimental example was 67 nm, while the CD bias in the sixth experimental example was 30 nm. From these results, it was confirmed that by using a first noble gas such as xenon gas in the second etching process, it is possible to enlarge the bottom CD and further rectangularize the shape of the recess in the vertical cross section.
• the plasma processing apparatus 1 was used to etch the silicon-containing film of the same sample substrate as in the first experimental example.
• the etching in the eighth to tenth experimental examples included a first etching step and a second etching step following the first etching step.
• a mixed gas containing HF gas, WF 6 gas, PF 3 gas, a halogen-containing gas, and a carbon-containing gas was used as the first processing gas in the first etching step.
• the halogen-containing gas contained NF 3 gas, Cl 2 gas, and HBr gas.
• the carbon-containing gas contained a hydrofluorocarbon gas.
• a mixed gas that is the same as the first processing gas in the eighth experimental example was used as the second processing gas in the second etching step, except that it did not contain WF 6 gas and PF 3 gas, but further contained xenon gas.
• the second process gas in the second etching step was the same mixed gas as the second process gas in the eighth experimental example, except that it contained O2 gas instead of NF3 gas.
• the second process gas in the second etching step was the same mixed gas as the second process gas in the ninth experimental example, except that it contained argon gas instead of xenon gas.
• the maximum width of the recess formed in the silicon-containing film i.e., bowing CD
• the width at the bottom of the recess i.e., bottom CD
• the difference between the bowing CD and the bottom CD i.e., the CD bias
• the bottom CD was 0.7 nm smaller than the bottom CD of the eighth experimental example, but the bowing CD was 2.3 nm smaller than the bowing CD of the eighth experimental example. Therefore, in the ninth experimental example, the CD bias was 1.6 nm smaller than the CD bias of the eighth experimental example.
• the bottom CD was enlarged from the bottom CD of the ninth experimental example, and as a result, the CD bias was 2.3 nm smaller than the CD bias of the ninth experimental example. From these results, it was confirmed that by using a second noble gas such as argon gas as a noble gas used together with O2 gas instead of NF3 gas in the second etching step, it is possible to increase the bottom CD and make the vertical cross-sectional shape of the recess more rectangular.
• a second noble gas such as argon gas as a noble gas used together with O2 gas instead of NF3 gas in the second etching step
• 1...plasma processing apparatus 2...control section, 10...plasma processing chamber, 10s...plasma processing space, 11...substrate support section, 13...shower head, 20...gas supply section, 31a...first RF generation section, 31b...second RF generation section, 32a...first DC generation section, SF...silicon-containing film, MF...mask, OP...opening, RC...recess, UF...undercoat film, W...substrate.

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