Substrate processing device and substrate processing method

Abstract

The purpose of the present invention is to provide a substrate processing device and a substrate processing method for stably generating plasma under low pressure.　In this substrate processing device, a step of supplying source RF signals to an upper electrode, generating plasma in the plasma processing chamber, and depositing a deposit on a substrate in a state where a magnetic field is generated by an electromagnet in the plasma processing chamber, and a step of supplying the source RF signals to the upper electrode, generating plasma in the plasma processing chamber, and etching the substrate in a state where a magnetic field is generated by the electromagnet in the plasma processing chamber, are repeated, and the power level of the source RF signals in the step of etching the substrate is lower than the power level of the source RF signals in the step of depositing the deposit on the substrate.

Description

Substrate processing apparatus and substrate processing method

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

[0002] Patent Document 1 discloses a substrate processing method for a substrate processing apparatus, the method comprising: a) supplying a process gas containing fluorocarbon and a rare gas to a processing vessel in which a mounting table for mounting a workpiece including a first region made of silicon oxide is placed; b) plasma processing the workpiece using a first plasma of the process gas generated under first plasma generation conditions; c) plasma processing the workpiece, on which a bias potential is generated, using a second plasma of the process gas generated under second plasma generation conditions different from the first plasma generation conditions; and d) repeating steps b) and c).

[0003] Japanese Patent Application Laid-Open No. 2021-150418

[0004] In one aspect, the present disclosure provides a substrate processing apparatus and a substrate processing method that stably generate plasma under low pressure.

[0005] In order to achieve the above object, according to one aspect, there is provided a plasma processing chamber regulated to a pressure within a range of 1 mTorr to 20 mTorr, a substrate support disposed within the plasma processing chamber and including a lower electrode for supporting a substrate, an upper electrode disposed above the substrate support, an electromagnet having at least two or more concentrically arranged annular coils, a first RF power supply configured to supply a source RF signal having a first RF frequency to the upper electrode, a second RF power supply configured to supply a bias RF signal having a second RF frequency to the lower electrode, and a controller, wherein the controller controls the electromagnet to be connected to the plasma processing chamber. a step of supplying the source RF signal to the upper electrode while the electromagnet generates a magnetic field within the plasma processing chamber to generate plasma in the plasma processing chamber and deposit a deposit on the substrate, and a step of supplying the source RF signal to the upper electrode while the electromagnet generates a magnetic field within the plasma processing chamber to generate plasma in the plasma processing chamber and deposit a deposit on the substrate, the step of etching the substrate being repeated, wherein a power level of the source RF signal in the step of etching the substrate is lower than a power level of the source RF signal in the step of depositing the deposit on the substrate.

[0006] According to one aspect, it is possible to provide a substrate processing apparatus and a substrate processing method that can stably generate plasma under low pressure.

[0007] 1 is a diagram for explaining an example of the configuration of a capacitively coupled plasma processing apparatus; FIG. 1 is a schematic diagram showing the state of plasma when the generation of a magnetic field by a magnetic field generating unit is stopped; FIG. 2 is a schematic diagram showing the state of plasma when a magnetic field is generated by a magnetic field generating unit; FIG. 3 is a time chart for an etching process; FIG. 4 is a schematic cross-sectional view of a structure formed on a substrate; FIG. 5 is a schematic cross-sectional view of a structure formed on a substrate; FIG. 6 is a diagram showing an example of a range in which plasma is stable; FIG. 7 is a diagram showing an example of a range in which plasma is stable; FIG. 8 is a diagram showing an example of a range in which plasma is stable; FIG. 9 is a graph showing the magnetic field on the surface of a substrate W under each coil condition; FIG. 10 is a diagram for explaining an example of the effect of applying a magnetic field by a magnetic field generating unit; FIG. 11 is a diagram showing a configuration in which an electromagnet has two coils, and an example of a magnetic field generated by the electromagnet; FIG. 12 is a diagram showing a configuration in which an electromagnet has two coils, and an example of a magnetic field generated by the electromagnet; FIG. 13 is a diagram showing a configuration in which an electromagnet has four coils, and an example of a magnetic field generated by the electromagnet;

[0008] Various exemplary embodiments will be described in detail below with reference to the drawings, in which the same or equivalent parts are designated by the same reference numerals.

[0009] [Plasma Processing System] An example of the configuration of a plasma processing system will be described below. Fig. 1 is an example of a diagram for explaining an example of the configuration of a capacitively coupled plasma processing apparatus (substrate processing apparatus) 1.

[0010] The plasma processing system includes a capacitively coupled plasma processing apparatus 1 and a controller 2. The capacitively coupled plasma processing apparatus 1 includes a plasma processing chamber 10, a gas supply 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 process 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 has at least one gas inlet for supplying at least one processing gas into the plasma processing space 10s and at least one gas outlet for exhausting gas from the plasma processing space 10s. 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.

[0011] 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 plan 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.

[0012] 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 can 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 the annular region 111b may also be provided by another member surrounding the electrostatic chuck 1111, such as an annular electrostatic chuck or an annular insulating member. 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. Furthermore, at least one RF / DC electrode coupled to an RF (Radio Frequency) power supply 31 and / or a DC (Direct Current) power supply 32 (described later) may 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 (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. Furthermore, the electrostatic electrode 1111b may function as a lower electrode. Therefore, the substrate support 11 includes at least one lower electrode.

[0013] 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.

[0014] 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 W 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. In one embodiment, 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.

[0015] The showerhead 13 is configured to introduce at least one process 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 process 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.

[0016] 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. Additionally, the gas supply unit 20 may include one or more flow modulation devices to modulate or pulse the flow rate of the at least one process gas.

[0017] 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 generates a plasma from at least one process gas supplied to the plasma processing space 10s. Therefore, the RF power supply 31 can function as at least a part of a plasma generating unit configured to generate a plasma from one or more process gases in the plasma processing chamber 10. Furthermore, by supplying a bias RF signal to the at least one lower electrode, a bias potential is generated on the substrate W, thereby attracting ion components in the formed plasma to the substrate W.

[0018] 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 (first RF power supply) 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 first RF frequency in the range of 10 MHz to 150 MHz (e.g., 60 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.

[0019] The second RF generator 31b (second RF power source) is coupled to the 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 second RF frequency (e.g., 12.88 MHz) in the range of 100 kHz to 60 MHz. In one embodiment, 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 supplied to the at least one lower electrode. In various embodiments, at least one of the source RF signal and the bias RF signal may be pulsed.

[0020] 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 the at least one lower electrode and configured to generate a first DC signal. The generated first bias DC signal is applied to the at least one lower electrode. In one embodiment, the second DC generator 32b is connected to the 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.

[0021] In various embodiments, at least one of 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 the 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 either 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 generating units 32a and 32b may be provided in addition to the RF power supply 31, or the first DC generating unit 32a may be provided instead of the second RF generating unit 31b.

[0022] 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 regulated by the pressure regulating valve. The vacuum pump may include a turbomolecular pump, a dry pump, or a combination thereof.

[0023] The plasma processing apparatus 1 also includes a magnetic field generating unit 50 that generates a magnetic field in the plasma processing space 10s. The magnetic field generating unit 50 includes an electromagnet 51 and a power supply 52.

[0024] The electromagnet 51 has multiple coils 511 and 512 (two in the example of FIG. 1 ). The coils 511 and 512 are annular coils arranged concentrically. The coil 512 is arranged radially outward of the coil 511. The coils 511 and 512 are arranged outside the plasma processing space 10s (outside the plasma processing chamber 10). The coils 511 and 512 are also arranged above the upper electrode (shower head 13). The coils 511 and 512 are also arranged concentrically with the central axis of the substrate support 11.

[0025] The power supply 52 supplies power to the electromagnet 51. The power supply 52 includes a power supply 521 that supplies power to the coil 511 and a power supply 522 that supplies power to the coil 512. Here, the power supply 521 supplies power to the coil 511 so that a current flows in one direction. Furthermore, the power supply 522 supplies power to the coil 512 so that a current flows in the direction opposite to the one direction. As a result, the magnetic fields generated by the coils 511 and 512 cancel each other out above the substrate W, thereby reducing the magnetic field above the substrate W.

[0026] The number of annular coils included in the electromagnet 51 is not limited to two and may be more than two. The electromagnet 51 may have an even number of coils, and current may flow in opposite directions between adjacent coils in the radial direction. The electromagnet 51 may also have multiple pairs of coils, each pair having current flowing in opposite directions. In the electromagnet 51 having multiple coils, the number of coils having current flowing in one direction may be equal to the number of coils having current flowing in the opposite direction. The electromagnet 51 may also have an odd number of coils, and current may flow in opposite directions between adjacent coils in the radial direction. Although the multiple coils have been described as being arranged at the same height, this is not limited thereto, and the coils may be arranged at different height positions.

[0027] The control unit 2 processes computer-executable instructions that cause the plasma processing apparatus 1 to perform 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 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 storage unit 2a2, and a communication interface 2a3. The control unit 2 may be implemented by, for example, a computer 2a. The processing unit 2a1 may be configured to read a program from the storage unit 2a2 and execute the read program to perform various control operations. This program may be stored in the storage unit 2a2 in advance or may be acquired via a medium when needed. The acquired program is stored in the storage unit 2a2 and read from the storage unit 2a2 by the processing unit 2a1 for execution. The medium may be various storage media readable by the computer 2a or a communication line connected to the communication interface 2a3. The processing unit 2a1 may be a CPU (Central Processing Unit). The storage unit 2a2 may include a random access memory (RAM), a read-only memory (ROM), a hard disk drive (HDD), a solid state drive (SSD), or a combination thereof. The communication interface 2a3 may communicate with the plasma processing apparatus 1 via a communication line such as a local area network (LAN).

[0028] Next, a method for controlling the plasma generated in the plasma processing space 10s by the magnetic field generating unit 50 will be described with reference to FIGS.

[0029] FIG. 2 is an example of a schematic diagram showing the state of plasma P1 when the generation of the magnetic field by the magnetic field generating unit 50 is stopped.

[0030] Here, a source RF signal (source RF power) is supplied to the upper electrode (shower head 13), thereby generating plasma P1 between the upper electrode (shower head 13) and the lower electrode (substrate support 11). The electron density in the plasma P1 is expressed as the electron density E Ｃｅｎｔｅｒ is the electron density E on the outer periphery Ｅｄｇｅ It is higher than Ｃｅｎｔｅｒ >E Ｅｄｇｅ In Figure 2, the density of electrons is shown schematically by the density of dotted hatching.

[0031] Also shown is a schematic diagram of an etching rate trend 251 when etching is performed on the substrate W. The etching rate trend 251 is correlated with the electron density in the plasma P1, and indicates a tendency for the etching rate to be higher on the central side of the substrate W and lower on the outer periphery of the substrate W.

[0032] In addition, charged particles 210 (e.g., electrons, etc.) in the plasma P1 move toward the lower electrode due to the bias RF signal (bias RF power) supplied to the lower electrode, and when they reach the sheath, the charged particles 210 disappear (shown by the dashed lines in Figure 2).

[0033] FIG. 3 is an example of a schematic diagram showing the state of the plasma P2 when the magnetic field is generated by the magnetic field generating unit 50. In FIG.

[0034] Here, a source RF signal (source RF power) is supplied to the upper electrode (shower head 13), thereby generating plasma P2 between the upper electrode (shower head 13) and the lower electrode (substrate support 11).

[0035] Here, an example of the magnetic flux 220 generated by the electromagnet 51 is shown by a solid arrow. As shown in FIG. 3, the magnetic flux 220 is directed toward the outer periphery. The charged particles 210 in the plasma P2 move toward the outer periphery due to the Lorentz force of the magnetic flux 220, which has a horizontal component. As a result, the electron density in the plasma P2 is increased by a factor of 10 to 15. Ｅｄｇｅ is the electron density E Ｃｅｎｔｅｒ It is higher than Ｃｅｎｔｅｒ <E Ｅｄｇｅ3, the density of electrons is shown schematically by the density of dotted hatching.

[0036] Also shown is a schematic diagram of an etching rate trend 252 when etching is performed on the substrate W. The etching rate trend 252 is correlated with the electron density in the plasma P2, and indicates a tendency for the etching rate to be higher on the outer periphery of the substrate W and lower on the center of the substrate W.

[0037] Furthermore, charged particles 210 (e.g., electrons) in the plasma P2 move toward the lower electrode due to the bias RF signal (bias RF power) supplied to the lower electrode, and when they reach the sheath, the charged particles 210 disappear (shown by the dashed line in FIG. 3). Comparing FIG. 2 with FIG. 3, the distance traveled by the charged particles 210 before reaching the sheath is longer in FIG. 3. In other words, the disappearance of the charged particles 210 can be delayed.

[0038] Here, improved plasma uniformity is required as semiconductor devices formed on substrates W become smaller. In addition, in plasma etching processes, the plasma generated in plasma processing chamber 10 controlled at a low pressure (1 mTorr to 20 mTorr) has high uniformity, resulting in improved uniformity of the etching rate.

[0039] On the other hand, under low pressure, it becomes difficult to maintain plasma because the density of gas molecules is low and collisions between gas molecules are reduced. Also, with the miniaturization of semiconductor devices formed on the substrate W, there is a limit to how much the intensity of the source RF signal (source RF power) that generates plasma can be increased.

[0040] As shown in Fig. 3, by applying a magnetic field from the magnetic field generating unit 50, the charged particles 210 in the plasma P2 move along the magnetic flux 220. This increases the distance the charged particles 210 travel before reaching the sheath. In other words, the probability that the charged particles 210 will collide with other gas molecules before reaching the sheath increases, increasing the density of the plasma. As a result, the plasma P2 shown in Fig. 3 can suppress plasma deactivation even under low pressure, compared to the plasma P1 shown in Fig. 2.

[0041] Next, an example of an etching process will be described with reference to Fig. 4 and Figs. 5A to 5B. Fig. 4 is an example of a time chart of the etching process. Figs. 5A to 5B are example of cross-sectional schematic views of a structure formed on a substrate W. In Fig. 4, the upper row shows the power (hereinafter also referred to as HF power) of a source RF signal (source RF power), and the lower row shows the power (hereinafter also referred to as LF power) of a bias RF signal (bias RF power).

[0042] First, the control unit 2 controls the transfer device (not shown) to transfer the substrate W to the substrate support 11 and have the substrate support 11 support the substrate W. Next, the control unit 2 controls the exhaust system 40 to control the pressure inside the plasma processing chamber 10 to a predetermined pressure. Here, the predetermined pressure is within a range of 1 mTorr to 20 mTorr. Furthermore, the predetermined pressure is preferably within a range of 1 mTorr to 10 mTorr, and more preferably within a range of 3 mTorr to 8 mTorr. Next, the control unit 2 controls the gas supply unit 20 to supply a processing gas. The processing gas is, for example, C ４ F ６ , Ar, O ２ The control unit 2 also controls the power supply 52 to supply power from the power supply 52 to the electromagnet 51 (coils 511 and 512) and cause the electromagnet 51 to generate a magnetic field.

[0043] Next, the control unit 2 controls the power supply 30 to supply a source RF signal (source RF power) to the upper electrode and a bias RF signal (bias RF power) to the lower electrode, thereby performing an etching process on the substrate W.

[0044] Here, the etching process repeats steps of depositing a deposit on the substrate W (S1, S2) and etching the substrate W (S3, S4).

[0045] 4, the HF power in the deposit deposition steps (S1, S2) is greater than the HF power in the etching steps (S3, S4). Also, the LF power in the deposit deposition steps (S1, S2) is less than the LF power in the etching steps (S3, S4). This results in the deposition amount of deposits on the surface of the substrate W being greater than the etching amount.

[0046] As shown in FIG. 5A, the substrate W is provided with an etching target film 510 (e.g., SiO ２ ) and a mask 520 (e.g., SiN) are laminated on top of each other, and recesses such as trenches and holes are formed through the mask 520 in the etching target film 510. In the steps (S1, S2) of depositing a deposit, a deposit 530 is deposited on the surface of the substrate W.

[0047] 4, the HF power in the etching steps (S3, S4) is lower than the HF power in the deposit deposition steps (S1, S2). The LF power in the etching steps (S3, S4) is higher than the LF power in the deposit deposition steps (S1, S2). This results in the etching amount being greater than the deposition amount of the deposit 530 on the surface of the substrate W.

[0048] As shown in FIG. 5B, in the etching steps (S3, S4), the bottom of the recess in the etching target film 510 is etched.

[0049] Each of steps S1 to S4 will be further described with reference to Figure 4. The depositing step (S1, S2) has a first period (S1) and a second period (S2). The etching step (S3, S4) has a third period (S3) and a fourth period (S4).

[0050] In step S1, HF power at a first power level is supplied to the upper electrode and LF power at a fifth power level is supplied to the lower electrode for a first period. Here, the first power level is in the range of 50 to 200 W. The fifth power level is in the range of 0 to 50 W. Here, by increasing the HF power, the deposition amount of deposits 530 on the surface of the substrate W becomes dominant over the etching amount. As a result, deposits 530 containing CFx are deposited on the upper surface of the mask 520 and on the side walls of recesses formed in the mask 520 and the etching target film 510.

[0051] In step S2, HF power at a second power level is supplied to the upper electrode and LF power at a sixth power level is supplied to the lower electrode for a second period of time. Here, the second power level is in the range of 50 to 200 W. The second power level is equal to the first power level. The sixth power level is higher than the fifth power level. Here, by increasing the HF power, the deposition amount of the deposit 530 on the surface of the substrate W becomes dominant over the etching amount. Furthermore, by increasing the LF power, ions are attracted into the recesses, and the deposit 530 is etched at the bottom of the recesses.

[0052] In step S3, HF power at a third power level is supplied to the upper electrode and LF power at a seventh power level is supplied to the lower electrode for a third period. Here, the third power level is within a range of 50 to 200 W. The third power level is lower than the first and second power levels. The seventh power level is higher than the sixth power level. Here, by reducing the HF power, the etching amount becomes dominant over the deposition amount of the deposit 530 on the surface of the substrate W. Furthermore, by further increasing the LF power, ions are attracted into the recesses, and the bottom of the recesses in the etching target film 510 is etched.

[0053] In step S4, for a fourth period, HF power at a fourth power level is supplied to the upper electrode, and LF power at an eighth power level is supplied to the lower electrode. Here, the fourth power level is within a range of 50 to 200 W. The fourth power level is lower than the first and second power levels and equal to the third power level. The eighth power level is higher than the seventh power level. Here, by reducing the HF power, the etching amount becomes dominant over the deposition amount of the deposit 530 on the surface of the substrate W. Furthermore, by further increasing the LF power, ions are attracted into the recesses, and the bottom of the recesses in the etching target film 510 is etched.

[0054] In this way, the processes of steps S1 to S4 constitute one cycle, and by repeating this cycle, the bottom of the recess in the etching target film 510 is etched while the mask 520 and the sidewall of the recess are protected by the deposit 530.

[0055] Furthermore, even if the HF power is reduced in the etching steps (S3, S4), deactivation of the plasma can be suppressed even under low pressure by applying a magnetic field by the magnetic field generating unit 50. Furthermore, the plasma generated in the plasma processing chamber 10 controlled to a low pressure becomes more uniform, resulting in improved uniformity of the etching rate.

[0056] Next, an example of stable plasma generation by applying a magnetic field from the magnetic field generating unit 50 will be described with reference to FIGS. 6A to 6D. FIGS. 6A to 6D are diagrams showing an example of a range in which plasma is stable. FIG. 6A shows a case in which coils 511 and 512 do not generate a magnetic field. FIG. 6B shows a case in which coil 511 generates a magnetic field of −18 G and coil 512 generates a magnetic field of +18 G. FIG. 6C shows a case in which coil 511 generates a magnetic field of −18 G and coil 512 generates a magnetic field of +36 G. FIG. 6D shows a case in which coil 511 generates a magnetic field of −36 G and coil 512 generates a magnetic field of +36 G. The table on the left shows a case in which the pressure in the plasma processing chamber 10 is 3 mTorr, and the table on the right shows a case in which the pressure in the plasma processing chamber 10 is 8 mTorr. X is the eighth power level, and Y is the seventh power level.

[0057] Here, the first and second power levels were set to 100 [W], the third and fourth power levels to 50 [W], the fifth power level to 0 [W], the sixth power level to 40 [W], the seventh power level to Y [W], and the eighth power level to X [W], and experiments were conducted to confirm whether plasma could be generated stably.

[0058] Those in which plasma was generated stably are marked with a "○", and those in which plasma was not generated stably are marked with a "-" or "X". In addition, those in which plasma was generated stably are clearly indicated by hatching.

[0059] At 8 mTorr, plasma was generated stably in many X and Y combinations, as shown in FIGS. 6A to 6D.

[0060] On the other hand, at 3 mTorr, as shown in FIG. 6A when no magnetic field was generated, plasma was not generated stably in many regions of X and Y combinations.

[0061] In contrast, as shown in FIGS. 6B to 6D when a magnetic field is generated at 3 mTorr, the region of combinations of X and Y where plasma is stably generated increases compared to FIG. 6A.

[0062] In this way, by applying the magnetic field generated by the magnetic field generating unit 50 to the inside of the plasma processing chamber 10, the range in which plasma can be stably generated is expanded even under low pressure (for example, 3 mTorr).

[0063] Next, the relationship between the magnetic field generated by the coils 511 and 512 and the magnetic field on the surface of the substrate W will be described with reference to FIG. 7. FIG. 7 is an example of a graph showing the magnetic field on the surface of the substrate W under each condition of the coils 511 and 512. Here, Zone 1 indicates the magnetic field generated by the coil 511. Zone 2 indicates the magnetic field generated by the coil 512. The magnetic field generated by the coil 511 is −18 [G], 0 [G], +18 [G], and the magnetic field generated by the coil 512 is −18 [G], 0 [G], +18 [G], +18 [G]. Simulation results of the radial position (wafer location) from the center of the substrate W and the magnetic field B at that position are shown for these combinations. The radius of the substrate W is assumed to be 150 [mm].

[0064] 7, when the combinations of (Zone 1, Zone 2) are (-18 [G], +18 [G]) and (+18 [G], -18 [G]), the effect of the magnetic field on the region of the substrate W is small. In other words, when the direction of the current flowing through the coil 511 and the direction of the current flowing through the coil 512 are opposite to each other, the effect of the magnetic field on the region of the substrate W is small. This makes it possible to suppress the effect of the magnetic field on the etching characteristics (etch rate, uniformity) of the substrate W.

[0065] 7, the current flowing through the coils 511 and 512 is controlled to reduce the influence of the magnetic field in the region of the substrate W, but the present invention is not limited to this. The current flowing through the coils 511 and 512 may be controlled to adjust the plasma density.

[0066] 8 is a diagram illustrating an example of the effect of applying a magnetic field by the magnetic field generation unit 50. Here, an example is described in which the combinations of (Zone 1, Zone 2) are (0 [G], 0 [G]), (-18 [G], +18 [G]), and (-18 [G], +36 [G]).

[0067] At (0 [G], 0 [G]), the magnetic field on the substrate support 11 is zero, so the number of charged particles in the plasma processing chamber 10 increases radially near the center.

[0068] At (-18 [G], +18 [G]), the magnetic field on the substrate W is substantially zero, and the magnetic field increases outside the substrate W. Therefore, the number of charged particles in the plasma processing chamber 10 increases near the outer periphery in the radial direction.

[0069] At (-18 G, +36 G), the magnetic field increases from the outer edge of the substrate W to the vicinity of the ring assembly 112 (edge ​​ring). As a result, the number of charged particles in the plasma processing chamber 10 increases radially near the outer periphery.

[0070] In this way, by controlling the magnetic fields generated by the coils 511 and 512, the plasma density in the radial direction can be adjusted.

[0071] 9A and 9B are diagrams showing an example of a configuration in which an electromagnet 51A includes two coils 511 and 512, and an example of a magnetic field generated by the electromagnet 51A. FIG. 9A is an example of a partially enlarged view of a substrate processing apparatus showing an example of the arrangement of the coils 511 and 512. FIG. 9B shows a radial position (Location) from the center of the substrate W and a simulation result of the magnetic field B at that position. The radius of the substrate W is 150 mm. In FIGS. 9A and 9B, the position where the magnetic field B reaches its peak is indicated by a dashed line.

[0072] 10A and 10B are diagrams showing an example of a configuration in which an electromagnet 51B includes four coils 511 to 514, and an example of a magnetic field generated by the electromagnet 51B. FIG. 10A is an example of a partially enlarged view of a substrate processing apparatus showing an example of the arrangement of the coils 511 to 514. FIG. 10B shows a radial position (Location) from the center of the substrate W and simulation results of the magnetic field B at that position. The radius of the substrate W is 150 mm. In FIGS. 10A and 10B, the position where the magnetic field B reaches its peak is indicated by a dashed line.

[0073] 9A and 10A, in the configuration having four coils 511 to 514, the coils are arranged further radially outward than in the configuration having two coils 511 to 512. As a result, as shown in a comparison between FIG. 9B and FIG. 10B, in the configuration having four coils 511 to 514, the plasma density near the side wall 10a can be increased compared to the configuration having two coils 511 to 512.

[0074] In this way, by changing the number and positions of the coils of the electromagnet, it is possible to adjust the position where the plasma density is high.

[0075] The embodiments disclosed above include, for example, the following aspects: (Supplementary Note 1) A plasma processing apparatus comprising: a plasma processing chamber regulated to a pressure within a range of 1 mTorr to 20 mTorr; a substrate support disposed within the plasma processing chamber, the substrate support including a lower electrode and configured to support a substrate; an upper electrode disposed above the substrate support; an electromagnet having at least two or more concentrically arranged annular coils; a first RF power supply configured to supply a source RF signal having a first RF frequency to the upper electrode; a second RF power supply configured to supply a bias RF signal having a second RF frequency to the lower electrode; and a controller, wherein the controller repeats the steps of: generating plasma in the plasma processing chamber by supplying the source RF signal to the upper electrode while a magnetic field is generated within the plasma processing chamber by the electromagnet, thereby depositing a deposit on the substrate; and etching the substrate by supplying the source RF signal to the upper electrode while a magnetic field is generated within the plasma processing chamber by the electromagnet. A substrate processing apparatus, wherein a power level of the source RF signal in the step of etching the substrate is lower than a power level of the source RF signal in the step of depositing the deposit on the substrate. (Supplementary Note 2) The substrate processing apparatus according to Supplementary Note 1, wherein a power level of the bias RF signal in the step of etching the substrate is higher than a power level of the bias RF signal in the step of depositing the deposit on the substrate. (Supplementary Note 3) The substrate processing apparatus according to Supplementary Note 1 or Supplementary Note 2, wherein the step of depositing the deposit on the substrate has a first period and a second period, the step of etching the substrate has a third period and a fourth period, the power levels of the source RF signal are a first power level in the first period, a second power level in the second period, a third power level in the third period, and a fourth power level in the fourth period, and the power levels of the bias RF signal are a fifth power level in the first period, a sixth power level in the second period, a seventh power level in the third period, and an eighth power level in the fourth period.(Supplementary Note 4) The substrate processing apparatus according to any one of Supplementary Notes 1 to 3, wherein the second power level is equal to the first power level, the third power level is lower than the second power level, the fourth power level is equal to the third power level, the sixth power level is higher than the fifth power level, the seventh power level is higher than the sixth power level, and the eighth power level is higher than the seventh power level. (Supplementary Note 5) The substrate processing apparatus according to Supplementary Note 4, wherein the fifth power level is 0 [W]. (Supplementary Note 6) The substrate processing apparatus according to any one of Supplementary Notes 1 to 5, wherein currents flow in opposite directions in radially adjacent coils of the electromagnet. (Supplementary Note 7) The substrate processing apparatus according to any one of Supplementary Notes 1 to 6, wherein a pressure in the plasma processing chamber is within a range of 1 mTorr to 10 mTorr. (Supplementary Note 8) The substrate processing apparatus according to any one of Supplementary Note 1 to Supplementary Note 6, wherein a pressure in the plasma processing chamber is within a range of 3 mTorr to 8 mTorr. (Supplementary Note 9) A substrate processing method for a substrate processing apparatus comprising: a plasma processing chamber adjusted to a pressure within a range of 1 mTorr to 20 mTorr; a substrate support disposed in the plasma processing chamber, the substrate support including a lower electrode and configured to support a substrate; an upper electrode disposed above the substrate support; an electromagnet having at least two or more concentrically arranged annular coils; a first RF power supply configured to supply a source RF signal having a first RF frequency to the upper electrode; and a second RF power supply configured to supply a bias RF signal having a second RF frequency to the lower electrode, the method comprising: repeating a step of generating plasma in the plasma processing chamber by supplying the source RF signal to the upper electrode while a magnetic field is generated in the plasma processing chamber by the electromagnet, and depositing a deposit on the substrate; and a step of generating plasma in the plasma processing chamber by supplying the source RF signal to the upper electrode while a magnetic field is generated in the plasma processing chamber by the electromagnet, and etching the substrate. A substrate processing method, wherein a power level of the source RF signal in the step of etching the substrate is lower than a power level of the source RF signal in the step of depositing the deposit on the substrate.

[0076] The present invention is not limited to the configurations described in the above embodiments, but may be combined with other elements, etc. These aspects can be changed without departing from the spirit of the present invention, and can be appropriately determined depending on the application form.

[0077] This application claims priority based on Japanese Patent Application No. 2023-197225, filed on November 21, 2023, the entire contents of which are incorporated herein by reference.

[0078] REFERENCE SIGNS LIST W substrate 1 plasma processing apparatus 2 control unit 10 plasma processing chamber 10a sidewall 10s plasma processing space 11 substrate support unit (lower electrode) 13 shower head (upper electrode) 20 gas supply unit 30 power supply 31 RF power supply 31a first RF generation unit (first RF power supply) 31b second RF generation unit (second RF power supply) 40 exhaust system 510 film to be etched 520 mask 530 deposit 50 magnetic field generation unit 51 electromagnets 511 to 514 coils 52, 521, 522 power supplies

Claims

1. A plasma processing chamber adjusted to a pressure within a range of 1 mTorr to 20 mTorr; a substrate support disposed within the plasma processing chamber, the substrate support including a lower electrode and supporting a substrate; an upper electrode disposed above the substrate support; an electromagnet having at least two or more concentrically arranged annular coils; a first RF power supply supplying a source RF signal having a first RF frequency to the upper electrode; a second RF power supply supplying a bias RF signal having a second RF frequency to the lower electrode; and a controller, wherein the controller repeats the steps of: while the electromagnet generates a magnetic field in the plasma processing chamber, supplying the source RF signal to the upper electrode to generate plasma in the plasma processing chamber and deposit a deposit on the substrate; and while the electromagnet generates a magnetic field in the plasma processing chamber, supplying the source RF signal to the upper electrode to generate plasma in the plasma processing chamber and etch the substrate. The substrate processing apparatus, wherein a power level of the source RF signal in the step of etching the substrate is lower than a power level of the source RF signal in the step of depositing the deposit on the substrate.

2. The substrate processing apparatus according to claim 1, wherein a power level of the bias RF signal in the step of etching the substrate is higher than a power level of the bias RF signal in the step of depositing the deposit on the substrate.

3. The substrate processing apparatus of claim 1, wherein the step of depositing the deposit on the substrate has a first period and a second period; the step of etching the substrate has a third period and a fourth period; the power level of the source RF signal is a first power level in the first period, a second power level in the second period, a third power level in the third period, and a fourth power level in the fourth period; and the power level of the bias RF signal is a fifth power level in the first period, a sixth power level in the second period, a seventh power level in the third period, and an eighth power level in the fourth period.

4. The substrate processing apparatus of claim 3, wherein the second power level is equal to the first power level, the third power level is less than the second power level, the fourth power level is equal to the third power level, the sixth power level is greater than the fifth power level, the seventh power level is greater than the sixth power level, and the eighth power level is greater than the seventh power level.

5. The substrate processing apparatus according to claim 4, wherein the fifth power level is 0 [W].

6. The substrate processing apparatus according to claim 1, wherein the electromagnet has radially adjacent coils through which currents flow in opposite directions.

7. The substrate processing apparatus according to claim 1, wherein the pressure in the plasma processing chamber is within the range of 1 mTorr to 10 mTorr.

8. The substrate processing apparatus according to claim 1, wherein the pressure in the plasma processing chamber is within the range of 3 mTorr to 8 mTorr.

9. A substrate processing method for a substrate processing apparatus comprising: a plasma processing chamber adjusted to a pressure within a range of 1 mTorr to 20 mTorr; a substrate support disposed within the plasma processing chamber, the substrate support including a lower electrode and supporting a substrate; an upper electrode disposed above the substrate support; an electromagnet having at least two or more concentrically arranged annular coils; a first RF power supply for supplying a source RF signal having a first RF frequency to the upper electrode; and a second RF power supply for supplying a bias RF signal having a second RF frequency to the lower electrode, the method comprising the steps of: generating plasma in the plasma processing chamber by supplying the source RF signal to the upper electrode while the electromagnet generates a magnetic field within the plasma processing chamber, and depositing a deposit on the substrate; and repeating the steps of: generating plasma in the plasma processing chamber by supplying the source RF signal to the upper electrode while the electromagnet generates a magnetic field within the plasma processing chamber, and etching the substrate; A method of processing a substrate, wherein a power level of the source RF signal in the step of etching the substrate is lower than a power level of the source RF signal in the step of depositing the deposit on the substrate.

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