WO2025197561A1 - Plasma treatment device, bias power source, and plasma treatment method - Google Patents

Abstract

A plasma treatment device disclosed herein comprises a chamber, a substrate support part, a gas supply part, a high-frequency power source, and a bias power source. The high-frequency power source is configured to supply a source high-frequency signal in order to generate plasma from a treatment gas. The bias power source is configured to supply a sequence of voltage pulses to the substrate support part by generating the voltage pulses at a time interval that is a reciprocal of a first frequency, in order to attract ions from the plasma to a substrate on the substrate support part. The bias power source is configured to gradually increase or decrease the voltage levels of a plurality of voltage pulses included in the sequence within a period having a time length that is a reciprocal of a second frequency which is lower than the first frequency and included within the range of 20-100 kHz, and to repeat the period.

Description

Plasma processing apparatus, bias power supply, and plasma processing method

Exemplary embodiments of the present disclosure relate to a plasma processing apparatus, a bias power supply, and a plasma processing method.

A plasma processing apparatus is used in plasma processing of a substrate. The plasma processing apparatus described in Patent Document 1 includes a source RF generating unit and first and second bias RF generating units. The source RF generating unit generates a source RF signal for plasma generation. The first and second bias RF generating units are coupled to a substrate support. The frequency of the bias signal generated by the first bias RF generating unit is different from the frequency of the bias signal generated by the second bias RF generating unit.

JP 2022-41874 A

This disclosure provides a technology that achieves different ion energy distributions while suppressing an increase in the number of bias power supplies.

In one exemplary embodiment, a plasma processing apparatus is provided. The plasma processing apparatus includes a chamber, a substrate support within the chamber, a gas supply, a radio frequency power supply, and a bias power supply. The gas supply is configured to supply a process gas into the chamber. The radio frequency power supply is configured to supply a source radio frequency signal to generate a plasma from the process gas. The bias power supply is configured to supply a sequence of voltage pulses to the substrate support by generating voltage pulses at a time interval that is the reciprocal of a first frequency to attract ions from the plasma to a substrate on the substrate support. The bias power supply is configured to stepwise increase or decrease the voltage level of multiple voltage pulses included in the sequence within a period having a time length that is the reciprocal of a second frequency that is lower than the first frequency and is in the range of 20 kHz to 100 kHz, and to repeat the period.

According to one exemplary embodiment, a technique is provided that allows different ion energy distributions to be obtained while suppressing an increase in the number of bias power supplies.

FIG. 1 is a diagram illustrating an example of the configuration of a plasma processing system. 1 is a diagram illustrating a schematic diagram of a plasma processing apparatus according to an exemplary embodiment; FIG. 2 is a schematic diagram of a bias power supply according to an exemplary embodiment. FIG. 2 illustrates an example sequence of voltage pulses that can be output by a bias power supply according to one exemplary embodiment. 5A is a diagram showing an example of an ion energy distribution when multiple voltage pulses in a sequence have the same voltage level, FIG. 5B is a diagram showing an example of an ion energy distribution when a bias RF signal is used, and FIG. 5C is a diagram showing a schematic diagram of an example of an ion energy distribution when the voltage levels of multiple voltage pulses in a sequence are increased or decreased in stages. FIG. 10 illustrates another example sequence of voltage pulses that can be output by a bias power supply according to an exemplary embodiment. FIG. 10 illustrates yet another example sequence of voltage pulses that can be output by a bias power supply in accordance with an exemplary embodiment. 1 is a flow chart illustrating a plasma processing method according to an exemplary embodiment. 9 is a partially enlarged cross-sectional view of an example substrate to which the plasma processing method shown in FIG. 8 can be applied. 4 is a timing chart relating to a step of a plasma processing method according to an example embodiment. 1 is a cross-sectional view of an example substrate associated with a plasma processing method according to an exemplary embodiment. 1 is a cross-sectional view of an example substrate associated with a plasma processing method according to an exemplary embodiment. FIG. 1 is a block diagram of a processing circuit for performing the operations described herein on a computer.

Various exemplary embodiments will be described in detail below with reference to the drawings. Note that the same or equivalent parts in each drawing will be designated by the same reference numerals.

FIG. 1 is a diagram illustrating an example configuration of a plasma processing system. In one embodiment, the plasma processing system includes a plasma processing device 1 and a control unit 2. The plasma processing system is an example of a substrate processing system, and the plasma processing device 1 is an example of a substrate processing device. The plasma processing device 1 includes a plasma processing chamber 10, a substrate support unit 11, and a plasma generation unit 12. The plasma processing chamber 10 has a plasma processing space. The plasma processing chamber 10 also has at least one gas supply port for supplying at least one processing gas to the plasma processing space, and at least one gas exhaust port for exhausting gas from the plasma processing space. The gas supply port is connected to the gas supply unit 20, which will be described later, and the gas exhaust port is connected to an exhaust system 40, which will be described later. The substrate support unit 11 is disposed in the plasma processing space and has a substrate support surface for supporting a substrate.

The plasma generation unit 12 is configured to generate plasma from at least one processing gas supplied into the plasma processing space. The plasma formed in the plasma processing space may be capacitively coupled plasma (CCP), inductively coupled plasma (ICP), electron-cyclotron-resonance plasma (ECR plasma), helicon wave plasma (HWP), or surface wave plasma (SWP), etc. Additionally, various types of plasma generating units may be used, including AC (Alternating Current) plasma generating units and DC (Direct Current) plasma generating units. In one embodiment, the AC signal (AC power) used in the AC plasma generating unit has a frequency in the range of 100 kHz to 10 GHz. Thus, AC signals include RF (Radio Frequency) signals and microwave signals. In one embodiment, the RF signal has a frequency in the range of 100 kHz to 150 MHz.

The control unit 2 processes computer-executable instructions that cause the plasma processing apparatus 1 to perform the various processes 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 processes described herein. In one embodiment, 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 memory 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 memory unit 2a2 and executing the read program. This program may be stored in the memory unit 2a2 in advance, or may be acquired via a medium when needed. The acquired program is stored in the memory unit 2a2 and read from the memory unit 2a2 by the processing unit 2a1 for execution. 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 RAM (Random Access Memory), ROM (Read Only Memory), HDD (Hard Disk Drive), SSD (Solid State Drive), or a combination thereof. The communication interface 2a3 may communicate with the plasma processing apparatus 1 via a communication line such as a LAN (Local Area Network).

Below, we will explain an example of the configuration of a capacitively coupled plasma processing apparatus as an example of plasma processing apparatus 1. Figure 2 is a diagram illustrating an example of the configuration of a capacitively coupled plasma processing apparatus.

The capacitively coupled plasma processing apparatus 1 includes a plasma processing chamber 10, a gas supply unit 20, a power supply 30, and an exhaust system 40. The plasma processing apparatus 1 also includes a substrate support 11 and a gas inlet. The gas inlet is configured to introduce at least one processing gas into the plasma processing chamber 10. The gas inlet includes a showerhead 13. The substrate support 11 is disposed within the plasma processing chamber 10. The showerhead 13 is disposed above the substrate support 11. In one embodiment, the showerhead 13 forms at least a portion of the ceiling of the plasma processing chamber 10. The plasma processing chamber 10 has a plasma processing space 10s defined by the showerhead 13, a sidewall 10a of the plasma processing chamber 10, and the substrate support 11. 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 a 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 planar view. The substrate W is disposed on the central region 111a of the main body 111, and 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.

In one embodiment, 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 another member surrounding the electrostatic chuck 1111, such as an annular electrostatic chuck or an annular insulating member, may also have the annular region 111b. In this case, 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 power supply 31 and/or a DC power supply 32, which will be described later, may also be disposed within the ceramic member 1111a. In this case, the at least one RF/DC electrode functions as a lower electrode. When a bias RF signal and/or a DC signal, which will be described later, is supplied to the at least one RF/DC electrode, the RF/DC electrode is also called a bias electrode. Note that the conductive member of the base 1110 and the at least one RF/DC electrode may function as multiple lower electrodes. Alternatively, the electrostatic electrode 1111b may function as a lower electrode. Therefore, the substrate support 11 includes at least one lower electrode.

The ring assembly 112 includes one or more annular members. In one embodiment, 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 path 1110a, or a combination thereof. A heat transfer fluid such as brine or gas flows through the flow path 1110a. In one embodiment, the flow path 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 unit configured to supply a heat transfer gas to a gap between the back surface of the substrate W and the central region 111a.

The showerhead 13 is configured to introduce at least one processing gas from the gas supply unit 20 into the plasma processing space 10s. The showerhead 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 showerhead 13 also includes at least one upper electrode. In addition to the showerhead 13, the gas inlet may also include one or more side gas injectors (SGIs) attached to one or more openings formed in the sidewall 10a.

The gas supply unit 20 may include at least one gas source 21 and at least one flow controller 22. In one embodiment, the gas supply unit 20 is configured to supply at least one process gas from a corresponding gas source 21 to the showerhead 13 via a corresponding flow controller 22. Each flow controller 22 may include, for example, a mass flow controller or a pressure-controlled flow controller. Furthermore, the gas supply unit 20 may include at least one flow modulation device that modulates or pulses 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. Therefore, the RF power supply 31 can function as at least a part of the plasma generation unit 12. Furthermore, by supplying a bias RF signal to 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.

In one embodiment, 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 is configured to generate a source RF signal (source RF power) for plasma generation. In one embodiment, the source RF signal has a frequency in the range of 10 MHz to 150 MHz. In one embodiment, 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 generating unit 31b is coupled to at least one lower electrode via at least one impedance matching circuit and is 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. In one embodiment, the bias RF signal has a frequency lower than the frequency of the source RF signal. In one embodiment, the bias RF signal has a frequency in the range of 100 kHz to 60 MHz. In one embodiment, the second RF generating unit 31b may be configured to generate multiple bias RF signals having different frequencies. The generated one or more bias RF signals are supplied 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. In one embodiment, 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. In one embodiment, 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.

In various embodiments, the first and second DC signals may be pulsed. In this case, 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. In one embodiment, 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. Thus, the first DC generator 32a and the waveform generator constitute a voltage pulse generator. When 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 positive or negative polarity. Furthermore, the sequence of voltage pulses may include one or more positive voltage pulses and one or more negative voltage pulses within one period. The first and second DC generators 32a and 32b may be provided in addition to the RF power supply 31, or the first DC generator 32a may be provided instead of the second RF generator 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.

In the plasma processing apparatus 1, the control unit 2 is used as the main control unit. In addition, in the plasma processing apparatus 1, the first RF generating unit 31a is used as a high-frequency power supply that generates a source RF signal (source high-frequency signal) for plasma generation.

Below, reference will be made to FIGS. 3 and 4 in addition to FIGS. 1 and 2. FIG. 3 is a diagram schematically illustrating a bias power supply according to one exemplary embodiment. FIG. 4 is a diagram illustrating an example sequence of voltage pulses that can be output by a bias power supply according to one exemplary embodiment. As shown in FIG. 3, the plasma processing apparatus 1 includes a bias power supply 50. The bias power supply 50 is used in the plasma processing apparatus 1 as a bias power supply including the above-mentioned first DC generation unit 32a. Note that the plasma processing apparatus 1 including this bias power supply 50 does not necessarily have to include the second RF generation unit 31b.

4, the bias power supply 50 is configured to supply a sequence S _VP of voltage pulses VP to the substrate support 11 to attract ions from the plasma in the plasma processing chamber 10 to the substrate W on the substrate support 11. The time interval Ti (minimum time interval) at which the voltage pulses VP are generated in the sequence S _VP is the reciprocal of the first frequency. The first frequency is, for example, greater than or equal to 200 kHz and less than or equal to 1 MHz. The first frequency may be, for example, less than or equal to 800 kHz. The first frequency may be, for example, 400 kHz.

As shown in FIG. 4 , the bias power supply 50 can adjust the voltage levels of the multiple voltage pulses VP in the sequence S _VP . The bias power supply 50 may stepwise increase or decrease the voltage levels of the multiple voltage pulses VP included in the sequence S _VP within a period CY having a time length Tc that is the reciprocal of the second frequency, and the period CY may be repeated. The second frequency is lower than the first frequency. The second frequency is in the range of 20 kHz to 100 kHz. In the example shown in FIG. 4 , the voltage levels of the multiple voltage pulses VP included in the sequence S _VP increase stepwise within the period CY.

Note that each of the multiple voltage pulses VP has a negative voltage level relative to the reference potential V0. The voltage level of each of the multiple voltage pulses VP is the difference between the reference potential V0 and the potential of the voltage pulse. The reference potential V0 may be, for example, ground potential (0 V).

The bias power supply 50 may be configured to change the duty ratio of the voltage pulse VP. The duty ratio is L _ON /L _Ti , where L _ON is the length of time that the voltage pulse VP is in the ON state during the time interval Ti, and L _Ti is the length of the time interval Ti. The duty ratio may be set to, for example, 0.2.

In one embodiment, the bias power supply 50 may include a variable DC power supply 51 and a pulse generator 52. The variable DC power supply 51 is configured to be able to adjust the voltage level of the output voltage from its negative terminal. The positive terminal of the variable DC power supply 51 is connected to a ground or reference potential line. The negative terminal of the variable DC power supply 51 is electrically coupled to the substrate support 11 via the pulse generator 52. The pulse generator 52 is configured to generate a sequence S _VP of voltage pulses VP by pulsing the output voltage of the variable DC power supply 51.

The bias power supply 50 may include a control unit 50c as at least one control unit. The control unit 50c may include a power supply control unit 51c. The power supply control unit 51c controls the variable DC power supply 51 to change the voltage level of the output voltage of the variable DC power supply 51. The voltage level of the voltage pulse VP in the sequence S _VP is adjusted by the control of the power supply control unit 51c. For example, the voltage level of the output voltage of the variable DC power supply 51 is adjusted by the control of the power supply control unit 51c, and the voltage levels of the multiple voltage pulses VP included in the sequence S _VP within the period CY are increased or decreased in a stepwise manner.

The pulse generator 52 may include a switching circuit 52s. The bias power supply 50 can output a sequence _SVP of voltage pulses VP by alternately switching the opening and closing of the switching circuit 52s. At least one controller of the bias power supply 50 may further include a pulse controller 52c. In one embodiment, the controller 50c may include the pulse controller 52c. The opening and closing of the switching circuit 52s is controlled by the pulse controller 52c. The duty ratio of the voltage pulses VP is controlled by the pulse controller 52c. The pulse controller 52c may be part of the pulse generator 52. The pulse controller 52c may be located outside the pulse generator 52. The power supply controller 51c may form a power supply device 51S together with the variable DC power supply 51. The power supply controller 51c may be located outside the power supply device 51S. The power supply controller 51c and the pulse controller 52c may be configured as a single controller. The single controller may be part of or separate from one of the power supply 51S and the pulse generator 52. The single controller may be the controller 50c or the controller 2.

Below, reference will be made to Figures 5(a), 5(b), and 5(c). Figure 5(a) is a diagram showing an example of ion energy distribution when multiple voltage pulses in a sequence have the same voltage level. Figure 5(b) is a diagram showing an example of ion energy distribution when a bias RF signal is used. Figure 5(c) is a diagram schematically showing an example of ion energy distribution when the voltage levels of multiple voltage pulses in a sequence are increased or decreased in stages.

When the voltage levels of the multiple voltage pulses VP in the sequence S _VP are constant and identical to each other, the energy distribution E1 of the ions supplied to the substrate on the substrate support 11 has a relatively narrow width centered on its peak, as shown in FIG. 5A. That is, when the voltage levels of the multiple voltage pulses VP in the sequence S _VP are constant and identical to each other, the ion energy is highly monochromatic. Note that the peak energy of the distribution E1 can be changed by adjusting the constant voltage levels of the multiple voltage pulses VP in the sequence S _VP . On the other hand, when a bias RF signal is used as the electrical bias, the energy distribution E2 of the ions supplied to the substrate on the substrate support 11 has a relatively wide width, as shown in FIG. 5B.

When the voltage levels of the multiple voltage pulses VP in the sequence S _VP are increased or decreased stepwise within the cycle CY, the energy distribution E3 of the ions supplied to the substrate on the substrate support 11 has a distribution including multiple peaks, as shown in FIG. 5C. The multiple peaks in distribution E3 correspond to the voltage levels of the multiple voltage pulses VP in the sequence S _VP within the cycle CY. As shown in FIG. 5C, distribution E3 is similar to distribution E2 shown in FIG. 5B. Therefore, the bias power supply 50 can produce the highly monochromatic ion energy distribution shown in FIG. 5A and the relatively wide energy distribution shown in FIG. 5C with a single power supply. In other words, the bias power supply 50 can obtain different ion energy distributions while suppressing an increase in the number of bias power supplies. Therefore, the plasma processing apparatus 1 can reduce the space required for bias power supplies around the chamber 10.

Reference will now be made to FIGS. 6 and 7 . Each of FIGS. 6 and 7 is a diagram illustrating another example of a voltage pulse sequence that can be output by a bias power supply according to an exemplary embodiment. In the example illustrated in FIG. 4 , the voltage levels of the multiple voltage pulses VP in the sequence S _VP within the period CY are increased in stages. As illustrated in FIG. 6 , the bias power supply 50 may also decrease the voltage levels of the multiple voltage pulses VP in the sequence S _VP within the period CY in stages. Furthermore, as illustrated by comparing FIGS. 4 and 7 , the bias power supply 50 may also be capable of changing the duty ratio of each of the multiple voltage pulses VP in the sequence S _VP .

Below, a plasma processing method according to one exemplary embodiment will be described with reference to Figures 8 to 12. Control of each part of the plasma processing apparatus 1 will also be described with reference to these figures. Figure 8 is a flow chart showing a plasma processing method according to one exemplary embodiment. Figure 9 is an enlarged partial cross-sectional view of an example substrate to which the plasma processing method shown in Figure 8 can be applied. Figure 10 is a timing chart related to one step of the plasma processing method according to one exemplary embodiment. Figures 11 and 12 are each a cross-sectional view of an example substrate related to the plasma processing method according to one exemplary embodiment. In the plasma processing method shown in Figure 8 (hereinafter referred to as "method MT"), each part of the plasma processing apparatus 1 can be controlled by the control unit 2.

As shown in FIG. 8, method MT includes steps ST1, ST2, and ST3. Method MT may further include step STJ.

In process ST1, a substrate W is prepared. The substrate W is transported into the chamber 10 by a transport device (e.g., a transport robot). The substrate W is placed on a substrate support 11 in the chamber 10. The substrate W may be held by an electrostatic chuck 1111 during the execution of the method MT.

As shown in FIG. 9, the substrate W may include a first region R1 and a second region R2. The first region R1 may have at least one recess R1a. The first region R1 may have multiple recesses R1a. Each recess R1a may be a recess for forming a contact hole. The recess R1a may be filled with the second region R2. The second region R2 may be provided to cover the first region R1.

In one embodiment, the first region R1 includes silicon and nitrogen. The first region R1 may include silicon nitride (SiN _x ). The first region R1 may be a region formed by, for example, CVD or the like, or may be a region obtained by nitriding silicon. The first region R1 may include a first portion including silicon nitride (SiN _x ) and a second portion including silicon carbide (SiC). In this case, the first portion has a recess R1 a.

The aspect ratio of the recess R1a may be, for example, 3 or more, 4 or more, 5 or more, or 10 or more. The aspect ratio of the recess R1a indicates the ratio of the depth of the recess R1a to the maximum width dimension of the recess R1a.

The second region R2 includes silicon and oxygen. The second region R2 may include silicon oxide (SiO _x ). The second region R2 may be a region formed by, for example, CVD or the like, or may be a region obtained by oxidizing silicon.

The substrate W may further include a third region R3. The third region R3 is provided on the second region R2. The third region R3 may include a metal, carbon, and nitrogen. Here, the metal includes tungsten. The third region R3 may have an opening OP3. The width of the opening OP3 may correspond to the width of the recess R1a.

The substrate W may include an underlying region UR and at least one raised region RA provided on the underlying region UR. The underlying region UR and the at least one raised region RA are covered by a first region R1. The underlying region UR may include silicon. A plurality of raised regions RA are located on the underlying region UR. Recesses R1a of the first region R1 are located between the plurality of raised regions RA. Each raised region RA may form a gate region of a transistor.

The substrate W may include a mask MK. The mask MK is provided on the third region R3. The mask MK may include metal or silicon. The mask MK may have an opening OPM. The opening OPM corresponds to the opening OP3 in the third region R3.

The substrate W prepared in step ST1 may have the shape shown in FIG. 9 as a result of plasma etching, or may have the shape shown in FIG. 9 from the time it is initially provided to the plasma processing chamber 10.

In method MT, step ST2 is then performed. In step ST2, the control unit 2 controls the gas supply unit 20 to supply a processing gas into the chamber 10.

The processing gas may contain metals constituting the chemical species from the plasma and an etching component for etching the second region R2. In one example, the processing gas may contain a metal-containing gas. The processing gas may contain an etching component-containing gas. The processing gas may contain a carbon-containing gas. The processing gas may contain a hydrogen-containing gas. In another example, the processing gas may contain at least one metal-containing gas selected from the group consisting of a tungsten-containing gas, a molybdenum-containing gas, and a titanium-containing gas immediately before the first region R1 is exposed. In one example, the processing gas contains a halide gas as an etching component. The metal-containing gas may be a metal halide-containing gas. The etching component is a component that etches the second region R2.

The metal-containing gas may include at least one selected from the group consisting of a tungsten-containing gas, a molybdenum-containing gas, and a titanium-containing gas. The tungsten-containing gas may include a tungsten halide gas. The tungsten halide gas may include at least one of tungsten hexafluoride (WF ₆ ) gas, tungsten hexabromide (WBr ₆ ) gas, tungsten hexachloride (WCl ₆ ) gas, and WF ₅ Cl gas. The tungsten-containing gas may include tungsten hexacarbonyl (W(CO) ₆ ) gas. The molybdenum-containing gas may include a molybdenum halide gas. The molybdenum halide gas may include at least one selected from the group consisting of molybdenum hexafluoride (MoF ₆ ) gas and molybdenum hexachloride (MoCl ₆ ) gas. The titanium-containing gas may include titanium tetrachloride (TiCl ₄ ).

The etching component-containing gas includes a halogenated gas. The halogenated gas may include at least one selected from the group consisting of a fluorine-containing gas, a chlorine-containing gas, and a bromine-containing gas. The fluorine-containing gas may include a fluorocarbon gas.

_The carbon-containing gas may include at least one selected from the group consisting of _CH4 gas, _C2H2 gas, _C2H4 gas, _CH3F gas, _{CH2F2 gas} , _CHF3 gas _, and CO gas.

The hydrogen-containing gas may include at least one selected from the group consisting of _H2 gas, _SiH4 gas, and _NH3 gas.

The process gas may further include a noble gas such as argon gas, helium gas, xenon gas, or neon gas, etc. The process gas may include nitrogen (N ₂ ) gas, for example.

In method MT, step ST3 is then performed. In step ST3, the second region R2 is etched using plasma PL generated from the processing gas in chamber 10. In step ST3, the second region R2 can be etched so as to expose the shoulder portion SH of the recess R1a of the first region R1. Step ST3 is performed while the processing gas supplied in step ST2 is present in the chamber. Step ST3 may also be performed while step ST2 is being performed.

FIG. 10 is a timing chart relating to one step of a plasma processing method according to one exemplary embodiment. In FIG. 10, "HF" indicates the power level of the source radio frequency signal HF supplied by the first RF generator 31a for plasma generation. Furthermore, "MF" ON indicates that a first sequence is being supplied from the bias power supply 50 to the substrate support 11, and "MF" OFF indicates that the supply of the first sequence is stopped. The first sequence is a sequence _SVP of multiple voltage pulses VP whose voltage levels are increased or decreased stepwise within a period CY, as shown in FIG. 4, FIG. 6, or FIG. 7. Furthermore, "LF" ON indicates that a second sequence is being supplied from the bias power supply 50 to the substrate support 11, and "LF" OFF indicates that the supply of the second sequence is stopped. The second sequence is a sequence _SVP of multiple voltage pulses VP having the same and constant voltage levels.

As shown in FIG. 10 , process ST3 includes a first period P1, a second period P2, a third period P3, and a fourth period P4. During the first period P1, the control unit 2 controls the first RF generator 31a (i.e., the high-frequency power supply) to supply a source high-frequency signal HF having a first power level L1 to generate plasma PL from the processing gas. During the first period P1, the supply of the first and second sequences may be stopped. During the first period P1, chemical species from the plasma PL are deposited on the surface of the substrate W to form a deposit DP, as shown in FIG. 11 . In one embodiment, the deposit DP may contain the above-mentioned metal components, such as tungsten and _WF6 .

The second period P2 is a period after or following the first period P1. During the second period P2, the control unit 2 controls the first RF generating unit 31a to supply a source high frequency signal HF having a second power level L2 to generate a plasma PL from the processing gas. The second power level L2 may be lower than the first power level L1. Also, during the second period P2, the control unit 2 controls the bias power supply 50 to supply a first sequence to the substrate support 11. The maximum voltage level of the multiple voltage pulses VP in the first sequence during the second period P2 may be lower than the constant voltage levels of the multiple voltage pulses VP in the second sequence during the third period P3 and the fourth period P4. During the second period P2, ions from the plasma PL are attracted to the deposit DP, modifying the deposit DP. During the second period P2, deposits DP etched by ions from the plasma PL may re-adhere to the shoulder portion SH, etc.

The third period P3 is a period following or following the second period P2. During the third period P3, the control unit 2 controls the first RF generator 31a to supply a source radio frequency signal HF having a third power level L3 to generate plasma PL from the processing gas. The third power level L3 may be lower than the first power level L1. The third power level L3 may be the same as or different from the second power level L2. During the third period P3, the control unit 2 controls the bias power supply 50 to supply a second sequence to the substrate support 11. During the third period P3, highly energetic ions from the plasma PL are attracted to the deposit DP, etching the deposit DP on the second region R2 and the second region R2. Note that the angular distribution of ions during the third period P3 may be wider than the angular distribution of ions during the fourth period P4.

The fourth period P4 is a period following or following the third period P3. During the fourth period P4, the control unit 2 controls the first RF generation unit 31a to set the power level of the source high frequency signal HF to a fourth power level L4. The fourth power level L4 is lower than the second power level L2 and the third power level L3. The fourth power level L4 may be zero. Also, during the fourth period P4, the control unit 2 controls the bias power supply 50 to supply a second sequence to the substrate support unit 11. During the fourth period P4, ions in the plasma PL remaining in the chamber 10 are attracted to the substrate W to further etch the second region R2. During the fourth period P4, the amount of ion flux and the energy of the ions are appropriately adjusted, and the ions are supplied to the second region R2 with relatively high vertical linearity. This results in a highly vertical shape being formed on the substrate W by etching the second region R2 (see, for example, Figure 12). At the end of the fourth period P4, the deposit DP on the substrate W may have disappeared.

In the subsequent step STJ, it is determined whether a stop condition is satisfied. The stop condition is satisfied, for example, when the cycle including steps ST2 and ST3 has been repeated a predetermined number of times. If the stop condition is not satisfied, the cycle including steps ST2 and ST3 is repeated. On the other hand, if the stop condition is satisfied, method MT ends.

Below, we describe examples of processing circuits that can be used as one or more processing circuits in a plasma processing apparatus, such as the control unit 2, the control unit 50c, the power supply control unit 51c, and the pulse control unit 52c. FIG. 13 is a block diagram of a processing circuit that performs the operations described herein on a computer. FIG. 13 illustrates a processing circuit 130 that can be used to control a control process on any computer. The descriptions or blocks in the flowcharts represent modules, segments, or portions of code that contain one or more executable instructions for implementing specific logical functions or steps of the process. As will be understood by those skilled in the art, other examples having functions that can be performed in a different order than that shown or described, such as substantially simultaneously or in reverse order, depending on the functionality involved, are included within the scope of exemplary embodiments of the present disclosure. The various elements, features, and processes described herein may be used independently of one another or may be combined in various ways. All conceivable combinations and subcombinations may be included within the scope of the present disclosure.

In FIG. 13, processing circuitry 130 includes a CPU 1200 that performs one or more of the control processes described above/below. Processing data and instructions may be stored in memory 1202. These processing data and instructions may be stored on a storage medium disk 1204, such as a hard disk drive (HDD) or a portable storage medium, or may be stored remotely. Furthermore, the present disclosure as claimed is not limited by the form of computer-readable medium on which the processing instructions according to the present invention are stored. For example, these instructions may be stored on a CD, DVD, flash memory, RAM, ROM, PROM, EPROM, EEPROM, hard disk, or any other information processing device such as a server and/or computer with which processing circuitry 130 communicates.

Furthermore, the claimed disclosure may be provided as a utility application, a background daemon, a component of an operating system, or a combination thereof. The claimed disclosure may be executed in conjunction with a CPU 1200 and an operating system known to those skilled in the art, such as Microsoft Windows (registered trademark), UNIX (registered trademark), Solaris (registered trademark), LINUX (registered trademark), Apple MAC-OS, etc.

The hardware elements making up the processing circuit 130 can be realized by a variety of circuit elements. Furthermore, each function of the above-described embodiments can be performed by a circuit including one or more processing circuits. As shown in FIG. 13, the processing circuit includes a specifically programmed processing unit, such as a processing unit (CPU) 1200. The processing circuit also includes devices such as application specific integrated circuits (ASICs) or conventional circuit components configured to perform the described functions.

In FIG. 13, the processing circuitry 130 includes a CPU 1200 that performs the above-described processing. The processing circuitry 130 may be a general-purpose computer or a specific dedicated machine. In one embodiment, when the processing device 1200 is programmed to control the plasma generating unit 12 and the gas supply unit 20 and/or to control the bias power supply 50, the processing circuitry 130 functions as a specific dedicated machine.

Alternatively or additionally, CPU 1200 may be implemented on an FPGA, ASIC, PLD, or using discrete logic circuitry, as will be understood by those skilled in the art. Furthermore, CPU 1200 may be implemented as multiple processing units that cooperate to execute the instructions of the processes of the present invention described above in parallel.

The processing circuitry 130 of FIG. 13 also includes a network controller 1206, such as an Intel Ethernet PRO network interface card from Intel Corporation, USA, for interfacing with a network 1228. As can be appreciated, the network 1228 may be a public network such as the Internet, a private network such as a LAN or WAN, or any combination thereof, and may also include sub-networks such as a PSTN or ISDN. The network 1228 may also be wired, such as an Ethernet network, or wireless, such as a cellular network including EDGE, 3G, and 4G wireless cellular systems. The wireless network may also be Wi-Fi, Bluetooth, or any other known form of wireless communication.

The processing circuitry 130 further includes a display device controller 1208, such as a graphics card or graphics adapter, for interfacing with a display device 1210, such as a monitor. A general-purpose I/O interface 1212 interfaces with a keyboard and/or mouse 1214 and a touch panel 1216, which may be integral with or separate from the display device 1210. The general-purpose I/O interface is also connected to various peripheral devices 1218, such as printers and scanners.

The storage controller 1224 is connected to the storage media disk 1204 via a communications bus 1226, such as ISA, EISA, VESA, PCI, etc., and all components of the processing circuit 130 are interconnected. For the sake of brevity, the general features and functions of the display device 1210, keyboard and/or mouse 1214, as well as the display device controller 1208, storage controller 1224, network controller 1206, audio controller 1220, and general-purpose I/O interface 1212 are not described herein as they are well known.

The exemplary circuit elements described in this disclosure may be substituted with other elements and may have different structures than the examples described herein. Furthermore, circuits configured to implement the features described herein may be implemented in multiple circuit units (e.g., chips), or these features may be incorporated into the circuitry of a single chipset.

The functions and features described herein may also be performed by various distributed components on the system. For example, one or more processing devices may perform the functions of these systems, where the processing devices are distributed across multiple components communicating within a network. Distributed components may include various human interface and communication devices (such as display monitors, smartphones, tablets, and personal digital assistants (PDAs)), as well as one or more client and server devices that may share processing. The network may be a private network such as a LAN or WAN, or a public network such as the Internet. Input to the system may be received directly by a user, or remotely in real time or as a batch process. Furthermore, some embodiments may be implemented on modules or hardware that are not identical to those described above. Accordingly, other embodiments are within the scope of the claims.

Various exemplary embodiments have been described above, but the present invention is not limited to the exemplary embodiments described above, and various additions, omissions, substitutions, and modifications may be made. Furthermore, elements from different embodiments can be combined to form other embodiments.

From the foregoing, it will be understood that various embodiments of the present disclosure have been described herein for illustrative purposes, and that various modifications may be made without departing from the scope and spirit of the present disclosure. Accordingly, the various embodiments disclosed herein are not intended to be limiting, with the true scope and spirit being indicated by the appended claims.

Various exemplary embodiments included in this disclosure are described below in [E1] to [E19].

[E1]
a chamber;
a substrate support within the chamber;
a gas supply configured to supply a process gas into the chamber;
a radio frequency power source configured to provide a source radio frequency signal to generate a plasma from the process gas;
a bias power supply configured to supply a sequence of voltage pulses to the substrate support by generating voltage pulses at a time interval that is the inverse of a first frequency to attract ions from the plasma to a substrate on the substrate support;
Equipped with
the bias power supply is configured to increase or decrease stepwise the voltage levels of the plurality of voltage pulses included in the sequence within a period having a time length that is the reciprocal of a second frequency that is lower than the first frequency and is included in a range of 20 kHz to 100 kHz, and to repeat the period.
Plasma processing equipment.

[E2]
The plasma processing apparatus of E1, wherein each of the plurality of voltage pulses has a voltage level in a negative direction relative to a reference potential, and the voltage level of each of the plurality of voltage pulses is the difference between the reference potential and the potential of the voltage pulse.

[E3]
The bias power supply
A variable DC power supply;
a pulse generator configured to pulse the output voltage of the variable DC power supply to generate the sequence of voltage pulses;
at least one controller configured to control the variable DC power supply and the pulse generator;
Including,
the at least one control unit is configured to control the variable DC power supply to change the voltage level of the output voltage so as to increase or decrease the voltage level of the plurality of voltage pulses in a stepwise manner.
The plasma processing apparatus according to E1 or E2.

[E4]
Further comprising a main control unit,
the main control unit, in a state where the substrate including a first region containing silicon and nitrogen and a second region containing silicon and oxygen is placed on the substrate support unit,
(a) supplying a process gas into the chamber from the gas supply unit;
(b) etching the second region using a plasma generated from the process gas in the chamber;
is configured to run
The (b) is
(b1) providing the source radio frequency signal having a first power level from the radio frequency power source during a first time period to generate a plasma from the process gas in the chamber and deposit chemical species from the plasma on the substrate;
(b2) providing the source radio frequency signal having a second power level from the radio frequency power supply, the second power level being lower than the first power level, to generate a plasma from the process gas during a second time period after the first time period, the second power level including providing the sequence of voltage pulses to the substrate support from the bias power supply;
(b3) during a third time period after the second time period, providing the source radio frequency signal having a third power level from the radio frequency power source that is lower than the first power level to generate a plasma from the process gas and etch the second region, the third power level including providing the sequence of voltage pulses to the substrate support from the bias power supply;
(b4) during a fourth time period after the third time period, supplying the sequence of voltage pulses from the bias power supply to the substrate support to further etch the second region using the plasma generated from the process gas, the fourth time period including setting a power level of the source radio frequency signal to a fourth power level lower than the second power level and the third power level;
Including,
The bias power supply
In the steps (b3) and (b4), the voltage levels of the plurality of voltage pulses included in the sequence are set to a substantially constant level;
In the step (b2), the voltage levels of the plurality of voltage pulses included in the sequence within the period are increased or decreased stepwise, and the period is repeated.
It is configured as follows:
The plasma processing apparatus according to any one of E1 to E3.

[E5]
The plasma processing apparatus of E4, wherein the bias power supply is configured to set the maximum voltage level of the plurality of voltage pulses in (b2) to a level lower than the voltage levels of the plurality of voltage pulses in (b3) and (b4).

[E6]
The plasma processing apparatus of E4 or E5, wherein the fourth power level is zero.

[E7]
The plasma processing apparatus according to any one of E4 to E6, wherein the second power level and the third power level are the same.

[E8]
The plasma processing apparatus according to any one of E4 to E7, wherein the processing gas contains a metal constituting the chemical species and an etching component for etching the second region.

[E9]
The plasma processing apparatus according to any one of E4 to E8, wherein the main control unit is configured to repeat (b).

[E10]
The plasma processing apparatus according to any one of E1 to E9, wherein the bias power supply is configured to be able to change the duty ratio of the voltage pulse.

[E11]
A bias power supply used in a plasma processing apparatus,
A variable DC power supply;
a pulse generator configured to pulse the output voltage of the variable DC power supply to generate a sequence of voltage pulses;
at least one controller configured to control the variable DC power supply and the pulse generator;
Including,
The at least one control unit
controlling the pulse generator to generate the voltage pulses at a time interval that is the inverse of a first frequency and apply the sequence to the substrate support to attract ions from a plasma in a chamber of the plasma processing apparatus to a substrate on a substrate support in the chamber;
a stepwise increase or decrease in voltage level of a plurality of voltage pulses included in the sequence within a period having a time length that is the reciprocal of a second frequency that is lower than the first frequency and is included in a range of 20 kHz to 100 kHz, and the voltage level of the output voltage is changed by controlling the variable DC power supply to repeat the period;
It is configured as follows:
Bias power supply.

[E12]
8. The bias power supply of claim 11, wherein each of the plurality of voltage pulses has a negative-going voltage level relative to a reference potential, and the voltage level of each of the plurality of voltage pulses is the difference between the reference potential and the potential of the voltage pulse.

[E13]
(a) providing a substrate in a chamber of a plasma processing apparatus, the substrate including a first region including silicon and nitrogen and a second region including silicon and oxygen;
(b) supplying a processing gas into a chamber of the plasma processing device;
(c) etching the second region using a plasma generated from the process gas in the chamber;
Including,
The plasma processing apparatus includes a bias power supply configured to supply a sequence of voltage pulses to the substrate support by generating voltage pulses at a time interval that is the inverse of a first frequency to draw ions from the plasma to the substrate on the substrate support within the chamber;
(c) includes increasing or decreasing stepwise the voltage levels of the plurality of voltage pulses included in the sequence within a period having a time length that is the reciprocal of a second frequency that is lower than the first frequency and is included in a range of 20 kHz to 100 kHz, and repeating the period.
Plasma treatment method.

[E14]
the plasma processing apparatus includes a radio frequency power supply configured to provide a source radio frequency signal to generate a plasma from the process gas;
The (c) is
(c1) providing the source radio frequency signal having a first power level from the radio frequency power source to generate a plasma from the process gas in the chamber for a first time period and deposit chemical species from the plasma on the substrate;
(c2) providing the source radio frequency signal having a second power level lower than the first power level from the radio frequency power supply to generate a plasma from the process gas during a second time period after the first time period, the second power level including providing the sequence of voltage pulses to the substrate support from the bias power supply;
(c3) during a third time period after the second time period, providing the source radio frequency signal having a third power level from the radio frequency power source that is lower than the first power level to generate a plasma from the process gas and etch the second region, the third power level including providing the sequence of voltage pulses to the substrate support from the bias power supply;
(c4) applying the sequence of voltage pulses from the bias power supply to the substrate support during a fourth time period after the third time period to further etch the second region using the plasma generated from the process gas, the fourth time period including setting a power level of the source radio frequency signal to a fourth power level lower than the second and third power levels;
Including,
In the steps (c3) and (c4), the voltage levels of the plurality of voltage pulses included in the sequence are set to a substantially constant level;
In (c2), the voltage levels of the plurality of voltage pulses included in the sequence within the period are increased or decreased stepwise, and the period is repeated.
The plasma processing method according to E13.

[E15]
The plasma processing method according to E14, wherein a maximum voltage level of the plurality of voltage pulses in (c2) is lower than the voltage levels of the plurality of voltage pulses in (c3) and (c4).

[E16]
The plasma processing method of any one of E14 and E15, wherein the fourth power level is zero.

[E17]
The plasma processing method according to any one of E14 to E16, wherein the second power level and the third power level are the same.

[E18]
The plasma processing method according to any one of E14 to E17, wherein the processing gas contains a metal constituting the chemical species and an etching component for etching the second region.

[E19]
The plasma processing method according to any one of E13 to E18, wherein (c) is repeated.

1... plasma processing apparatus, 10... plasma processing chamber, 11... substrate support section, 12... plasma generation section, 20... gas supply section, 50... bias power supply, 50c... control section, 51c... power supply control section, 51... variable DC power supply, 52... pulse generator.

Claims (19)

a chamber;
a substrate support within the chamber;
a gas supply configured to supply a process gas into the chamber;
a radio frequency power source configured to provide a source radio frequency signal to generate a plasma from the process gas;
a bias power supply configured to supply a sequence of voltage pulses to the substrate support by generating voltage pulses at a time interval that is the inverse of a first frequency to attract ions from the plasma to a substrate on the substrate support;
Equipped with
the bias power supply is configured to increase or decrease stepwise the voltage levels of the plurality of voltage pulses included in the sequence within a period having a time length that is the reciprocal of a second frequency that is lower than the first frequency and is included in a range of 20 kHz to 100 kHz, and to repeat the period.
Plasma processing equipment. The plasma processing apparatus of claim 1, wherein each of the plurality of voltage pulses has a voltage level in a negative direction relative to a reference potential, and the voltage level of each of the plurality of voltage pulses is the difference between the reference potential and the potential of the voltage pulse. The bias power supply
A variable DC power supply;
a pulse generator configured to pulse the output voltage of the variable DC power supply to generate the sequence of voltage pulses;
at least one controller configured to control the variable DC power supply and the pulse generator;
Including,
the at least one control unit is configured to control the variable DC power supply to change the voltage level of the output voltage so as to increase or decrease the voltage level of the plurality of voltage pulses in a stepwise manner.
3. The plasma processing apparatus according to claim 1 or 2. Further comprising a main control unit,
the main control unit, in a state where the substrate including a first region containing silicon and nitrogen and a second region containing silicon and oxygen is placed on the substrate support unit,
(a) supplying a process gas into the chamber from the gas supply unit;
(b) etching the second region using a plasma generated from the process gas in the chamber;
is configured to run
The (b) is
(b1) providing the source radio frequency signal having a first power level from the radio frequency power source for a first time period to generate a plasma from the process gas in the chamber and deposit chemical species from the plasma on the substrate;
(b2) providing the source radio frequency signal having a second power level from the radio frequency power supply, the second power level being lower than the first power level, to generate a plasma from the process gas during a second time period after the first time period, the second power level including providing the sequence of voltage pulses to the substrate support from the bias power supply;
(b3) during a third time period after the second time period, providing the source radio frequency signal having a third power level from the radio frequency power source that is lower than the first power level to generate a plasma from the process gas and etch the second region, the third power level including providing the sequence of voltage pulses to the substrate support from the bias power supply;
(b4) during a fourth time period after the third time period, supplying the sequence of voltage pulses from the bias power supply to the substrate support to further etch the second region using the plasma generated from the process gas, the fourth time period including setting a power level of the source radio frequency signal to a fourth power level lower than the second power level and the third power level;
Including,
The bias power supply
In the steps (b3) and (b4), the voltage levels of the plurality of voltage pulses included in the sequence are set to a substantially constant level;
In the step (b2), the voltage levels of the plurality of voltage pulses included in the sequence within the period are increased or decreased stepwise, and the period is repeated.
It is configured as follows:
3. The plasma processing apparatus according to claim 1 or 2. The plasma processing apparatus of claim 4, wherein the bias power supply is configured to set the maximum voltage level of the plurality of voltage pulses in (b2) to a level lower than the voltage levels of the plurality of voltage pulses in (b3) and (b4). The plasma processing apparatus of claim 4, wherein the fourth power level is zero. The plasma processing apparatus of claim 4, wherein the second power level and the third power level are identical to each other. The plasma processing apparatus of claim 4, wherein the processing gas contains a metal constituting the chemical species and an etching component for etching the second region. The plasma processing apparatus of claim 4, wherein the main control unit is configured to repeat (b). The plasma processing apparatus of claim 1 or 2, wherein the bias power supply is configured to change the duty ratio of the voltage pulse. A bias power supply used in a plasma processing apparatus,
A variable DC power supply;
a pulse generator configured to pulse the output voltage of the variable DC power supply to generate a sequence of voltage pulses;
at least one controller configured to control the variable DC power supply and the pulse generator;
Including,
The at least one control unit
controlling the pulse generator to generate the voltage pulses at a time interval that is the inverse of a first frequency and apply the sequence to the substrate support to attract ions from a plasma in a chamber of the plasma processing apparatus to a substrate on a substrate support in the chamber;
a stepwise increase or decrease in voltage level of a plurality of voltage pulses included in the sequence within a period having a time length that is the reciprocal of a second frequency that is lower than the first frequency and is included in a range of 20 kHz to 100 kHz, and the voltage level of the output voltage is changed by controlling the variable DC power supply to repeat the period;
It is configured as follows:
Bias power supply. A bias power supply as described in claim 11, wherein each of the plurality of voltage pulses has a negative voltage level relative to a reference potential, and the voltage level of each of the plurality of voltage pulses is the difference between the reference potential and the potential of the voltage pulse. (a) providing a substrate in a chamber of a plasma processing apparatus, the substrate including a first region including silicon and nitrogen and a second region including silicon and oxygen;
(b) supplying a processing gas into a chamber of the plasma processing device;
(c) etching the second region using a plasma generated from the process gas in the chamber;
Including,
The plasma processing apparatus includes a bias power supply configured to supply a sequence of voltage pulses to the substrate support by generating voltage pulses at a time interval that is the inverse of a first frequency to draw ions from the plasma to the substrate on the substrate support within the chamber;
(c) includes increasing or decreasing stepwise the voltage levels of the plurality of voltage pulses included in the sequence within a period having a time length that is the reciprocal of a second frequency that is lower than the first frequency and is included in a range of 20 kHz to 100 kHz, and repeating the period.
Plasma treatment method. the plasma processing apparatus includes a radio frequency power supply configured to provide a source radio frequency signal to generate a plasma from the process gas;
The (c) is
(c1) providing the source radio frequency signal having a first power level from the radio frequency power source to generate a plasma from the process gas in the chamber for a first time period and deposit chemical species from the plasma on the substrate;
(c2) providing the source radio frequency signal having a second power level lower than the first power level from the radio frequency power supply to generate a plasma from the process gas during a second time period after the first time period, the second power level including providing the sequence of voltage pulses to the substrate support from the bias power supply;
(c3) during a third time period after the second time period, providing the source radio frequency signal having a third power level from the radio frequency power source that is lower than the first power level to generate a plasma from the process gas and etch the second region, the third power level including providing the sequence of voltage pulses to the substrate support from the bias power supply;
(c4) during a fourth time period after the third time period, supplying the sequence of voltage pulses from the bias power supply to the substrate support to further etch the second region using the plasma generated from the process gas, the fourth time period including setting a power level of the source radio frequency signal to a fourth power level lower than the second power level and the third power level;
Including,
In the steps (c3) and (c4), the voltage levels of the plurality of voltage pulses included in the sequence are set to a substantially constant level;
In (c2), the voltage levels of the plurality of voltage pulses included in the sequence within the period are increased or decreased stepwise, and the period is repeated.
The plasma processing method according to claim 13 . The plasma processing method of claim 14, wherein the maximum voltage level of the plurality of voltage pulses in (c2) is lower than the voltage levels of the plurality of voltage pulses in (c3) and (c4). The plasma processing method of claim 14 or 15, wherein the fourth power level is zero. The plasma processing method of claim 14 or 15, wherein the second power level and the third power level are the same. The plasma processing method according to claim 14 or 15, wherein the processing gas contains a metal constituting the chemical species and an etching component for etching the second region. The plasma processing method described in any one of claims 13 to 15, wherein (c) is repeated.