Plasma processing device

Abstract

This plasma processing device comprises: a plasma processing chamber that has a plasma processing space therein; a substrate support part that is provided inside the plasma processing chamber and supports a substrate; a plasma generation part that generates plasma in the plasma processing space; and a magnetic field generation part that is provided above the substrate support part and generates a magnetic field in the plasma processing space. The magnetic field generation part includes: a plurality of electromagnets that are arranged in the horizontal direction; and magnets that are provided on the inner side from electromagnets positioned closest to the center axis of the substrate support part among the plurality of electromagnets and that are provided at a position close to the substrate support part.

Description

Plasma processing equipment

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

[0002] Patent Literature 1 discloses a plasma processing apparatus equipped with an electromagnet above an upper electrode provided in a processing chamber. The electromagnet includes multiple coils arranged horizontally, and generates a magnetic field in a plasma processing space based on an excitation current supplied from an electromagnet excitation circuit. The plasma processing apparatus can control a sheath electric field using the generated magnetic field. For example, by flattening the sheath electric field horizontally, it is possible to suppress tilting, in which ions in the plasma are incident obliquely, during plasma processing (etching).

[0003] Japanese Patent Application Laid-Open No. 2015-201552

[0004] The present disclosure provides techniques that can improve the uniformity and stability of plasma processing.

[0005] According to one aspect of the present disclosure, there is provided a plasma processing apparatus comprising: a plasma processing chamber having a plasma processing space therein; a substrate support portion disposed inside the plasma processing chamber and supporting a substrate; a plasma generation portion disposed above the substrate support portion and generating a magnetic field in the plasma processing space; and a magnetic field generation portion disposed above the substrate support portion and generating a magnetic field in the plasma processing space, wherein the magnetic field generation portion includes a plurality of electromagnets arranged horizontally, and a magnet disposed inward of the electromagnet closest to the central axis of the substrate support portion and in close proximity to the substrate support portion.

[0006] According to one aspect, the uniformity and stability of plasma processing can be improved.

[0007] 1A to 1D are side views illustrating an example of the configuration of a capacitively coupled plasma processing apparatus according to the first embodiment.

[0034] FIG. 4A is a cross-sectional plan view of a shower head having a magnetic field generating unit according to the first embodiment.

[0035] FIG. 4B is a cross-sectional plan view of a magnetic field generating unit according to a reference example.

[0036] FIG. 4B is a cross-sectional side view of a magnetic field generating unit according to a first modified example and its periphery.

[0037] FIG. 4C is a cross-sectional side view of a magnetic field generating unit according to a second modified example and its periphery.

[0038] FIG. 1D is a cross-sectional side view of a magnetic field generating unit according to the second embodiment, viewed from above in the vertical direction.

[0039] FIGS. 10A to 10D are side views illustrating an example of adjusting the height positions of the electromagnets of the magnetic field generating unit.

[0039] FIG. 11A is a side view illustrating an example of the arrangement of the electromagnets when the electric field strength in the space is high.

[0039] FIG. 11B is a side view illustrating an example of the arrangement of the electromagnets when the electric field strength in the space is low. Fig. 11(C) is a side view showing the risk of electromagnetic interference in each fixed electromagnet of the magnetic field generating unit according to the reference example. Fig. 12(A) is a diagram illustrating an etching rate before adjusting the height position of each electromagnet. Fig. 12(B) is a diagram illustrating manipulation of the etching rate by adjusting the height position of each electromagnet. Fig. 13(A) is a diagram illustrating charge-up damage before adjusting the height position of each electromagnet. Fig. 13(B) is a diagram illustrating manipulation of charge-up damage by adjusting the height position of each electromagnet. A flowchart showing a plasma processing method for a plasma processing apparatus. Fig. 12(C) is a side cross-sectional view showing a magnetic field generating unit according to a third modified example.

[0008] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals, and redundant explanations may be omitted.

[0009] First Embodiment An example of the configuration of a plasma processing system will be described below: Fig. 1 is a diagram for explaining an example of the configuration of a capacitively coupled plasma processing apparatus according to a first embodiment.

[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 to 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 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 backside 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 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.

[0019] The second RF generator 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 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 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 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).

[0024] The plasma processing apparatus 1 according to the embodiment includes a magnetic field generating unit 50 that is provided above the substrate support unit 11 across the plasma processing space 10s and generates a magnetic field in the plasma processing space 10s. The magnetic field generating unit 50 shown in Fig. 1 is provided in the shower head 13 that functions as an upper electrode to which an RF power supply 31 (plasma generating unit) is connected. For example, the magnetic field generating unit 50 is installed vertically above the gas diffusion chamber 13b of the shower head 13.

[0025] The magnetic field generating unit 50 includes a plurality of electromagnets 51 arranged horizontally within the shower head 13. The plurality of electromagnets 51 are arranged at a first height. Each electromagnet 51 has a core member and a coil wound around this core member. A yoke or the like for inducing magnetic flux may be provided around each electromagnet 51.

[0026] 2 is a plan cross-sectional view showing a shower head having a magnetic field generating unit 50 according to the first embodiment. As shown in FIG. 2, the electromagnets 51 are formed in an annular (ring-like) shape and are arranged concentrically about the central axis of the plasma processing chamber 10. The central axis of the plasma processing chamber 10 also corresponds to the central axis of the plasma processing space 10s, the substrate support 11, the shower head 13, etc. The electromagnets 51 are arranged at equal intervals along the radial direction (horizontal direction) of the shower head 13 in a side cross-sectional view (see also FIG. 1).

[0027] More specifically, the electromagnets 51 include, in order from the central axis of the plasma processing chamber 10 toward the radially outward direction, a first electromagnet 51 a, a second electromagnet 51 b, a third electromagnet 51 c, a fourth electromagnet 51 d, and a fifth electromagnet 51 e. In the illustrated example, the first electromagnet 51 a, the second electromagnet 51 b, the third electromagnet 51 c, the fourth electromagnet 51 d, and the fifth electromagnet 51 e have the same cross-sectional shape (width, thickness), but this cross-sectional shape may differ among the electromagnets 51. The cross-sectional shape of each electromagnet 51 may be designed as appropriate depending on the target magnetic field distribution formed by each electromagnet 51, etc.

[0028] As shown in FIG. 1 , the diameter of the outer edge of the third electromagnet 51c is smaller than the diameter of the substrate W. Therefore, the first to third electromagnets 51a to 51c are provided at positions that overlap the substrate W placed on the substrate support 11 in a plan view. In one embodiment, the third electromagnet 51c overlaps the edge region of the substrate W on the substrate support 11 in a plan view. On the other hand, the diameter of the outer edge of the fourth electromagnet 51d is larger than the diameter of the substrate W, and is set to be approximately the same as the diameter of the outer edge of the ring assembly 112, for example. Therefore, the fourth electromagnet 51d is provided at a position that overlaps the ring assembly 112 placed on the substrate support 11 in a plan view. That is, the fourth electromagnet 51d overlaps with the edge ring included in the ring assembly 112 in a plan view. The fifth electromagnet 51e, which is located outside the fourth electromagnet 51d, is provided at a position that does not face the substrate support 11 (ring assembly 112) in a plan view. That is, the fifth electromagnet 51e is disposed outside the substrate support portion 11 in a plan view.

[0029] The coils of the first electromagnet 51a to the fifth electromagnet 51e are electrically connected to an electromagnet excitation circuit 59 via respective wirings. The electromagnet excitation circuit 59 supplies excitation currents to the first electromagnet 51a to the fifth electromagnet 51e based on commands from the control unit 2. The electromagnet excitation circuit 59 can adjust the amount of each excitation current supplied to the first electromagnet 51a to the fifth electromagnet 51e based on commands from the control unit 2. Furthermore, the electromagnet excitation circuit 59 can supply excitation currents to any combination (or individually) of the first electromagnet 51a to the fifth electromagnet 51e.

[0030] The magnetic field generating unit 50 supplies excitation currents from the electromagnet excitation circuit 59 to each electromagnet 51 to generate an appropriate magnetic field in the plasma processing space 10s below the shower head 13. The first to fifth electromagnets 51a to 51e work in conjunction with one another to generate a magnetic field in the plasma processing space 10s, with each electromagnet exerting the greatest influence on the magnetic field vertically below its installation position. Specifically, the first electromagnet 51a influences the magnetic field in Zone 1, which is located closer to the central axis of the plasma processing space 10s. The second electromagnet 51b influences the magnetic field in Zone 2, which is adjacent to and radially outward from Zone 1. The third electromagnet 51c influences the magnetic field in Zone 3, which is adjacent to and radially outward from Zone 2. The fourth electromagnet 51d influences the magnetic field in Zone 4, which is adjacent to and radially outward from Zone 3. The fifth electromagnet 51e influences the magnetic field in Zone 5, which is adjacent to and radially outward from Zone 4. The magnetic fields of zones 1 to 5 form a magnetic field distribution in the plasma processing space 10s such that the magnetic fields of zones 1 to 5 are continuous with each other.

[0031] When plasma is generated in the plasma processing space 10s, the plasma density tends to be higher in the central region (around the central axis) of the plasma processing space 10s. If no magnetic field is formed in the plasma processing space 10s, a sheath electric field is formed in accordance with the plasma density, with the gradient (inclination) being lower in the central region and higher in the peripheral region. This gradient of the sheath electric field causes tilting of the contact hole during etching of the substrate W (substrate processing).

[0032] The first electromagnet 51a to the fifth electromagnet 51e form an appropriate magnetic field distribution, thereby controlling the gradient of the sheath electric field and improving tilting. Specifically, based on the premise that plasma density is high in the central region during plasma processing, the magnetic field distribution is such that the magnetic field in Zone 1 near the central axis is weakened, while the magnetic field is gradually increased from Zone 1 toward Zone 5 (radially outward). This encourages the plasma density to move radially outward. Therefore, tilting is suppressed at radially outer positions away from the central axis of the plasma processing space 10s.

[0033] However, in the conventional magnetic field distribution formed by the plurality of electromagnets, the magnetic field near the central axis of the plasma processing space 10s was not sufficiently weak (weak magnetic field), and could not fully cope with the increased plasma density in the central region. In other words, even if the excitation current supplied to the first electromagnet 51a installed near the central axis was adjusted to the maximum in the electromagnet excitation circuit 59, it was difficult to make the magnetic field in the central region of the magnetic field distribution sufficiently weak.

[0034] Therefore, the magnetic field generating unit 50 according to the embodiment is configured such that a central region electromagnet 52 (magnet) is located inward and vertically lower (closer to the substrate support 11) than the first electromagnet 51a, which is located closest to the central axis of the substrate support 11 among the multiple electromagnets 51. This central region electromagnet 52 has the greatest effect on the magnetic field in Zone 0, which is located radially inward of Zone 1. That is, the central region electromagnet 52 cooperates with the first electromagnet 51a through the fifth electromagnet 51e to form a magnetic field, thereby significantly reducing the magnetic field in the central region of the plasma processing space 10s. Therefore, the central region electromagnet 52 is located at a second height different from the first height. In one embodiment, the second height is smaller than the first height.

[0035] Specifically, the central region electromagnet 52 is also formed in an annular shape in a planar cross-sectional view (see FIG. 2 ) and revolves around the center O of the showerhead 13. The central region electromagnet 52 is also arranged concentrically with the first electromagnet 51 a to the fifth electromagnet 51 e. Like the first electromagnet 51 a to the fifth electromagnet 51 e, the central region electromagnet 52 is also connected to the electromagnet excitation circuit 59 via wiring, and can generate a magnetic field by supplying an excitation current from the electromagnet excitation circuit 59.

[0036] 3 is a diagram for explaining the relationship between the first electromagnet 51a and the central region electromagnet 52. As shown in FIG. 3, the shape and installation position of the central region electromagnet 52 are preferably designed in relation to the adjacent first electromagnet 51a.

[0037] Specifically, when the distance from the inner peripheral surface of the first electromagnet 51a to the center O of the shower head 13 is D1i, the distance from the inner peripheral surface of the central region electromagnet 52 to the center O of the shower head 13 is D2i, and the distance from the inner peripheral surface of the central region electromagnet 52 to the center O of the shower head 13 is D2o, the central region electromagnet 52 may be arranged at a position where the relationship of the following formula (1) holds.

[0038] D2i < D1i < D2o … (1)

[0039] That is, formula (1) indicates that the central region electromagnet 52 overlaps the first electromagnet 51a in plan view. However, the central region electromagnet 52 and the first electromagnet 51a do not necessarily overlap in plan view. Therefore, the relationship of D2o < D1i may also hold. Accordingly, at least a part of the central region electromagnet 52 is arranged inside the first electromagnet 51a in plan view. In one embodiment, the central region electromagnet 52 overlaps the first electromagnet 51a in plan view.

[0040] Further, the shape of the central region electromagnet 52 may be designed such that the following formula (2) holds for D2i which is the radius of the inner peripheral surface.

[0041] 0 ≤ D2i … (2)

[0042] That is, when D2i = 0 in formula (2), it indicates that the central region electromagnet 52 is a single member that straddles the center O without having a cavity at the center O. Also, when D2i < 0 in formula (2), it indicates that the central region electromagnet 52 is an annular shape having a cavity at the center.

[0043] Further, when the distance from the lower surface of the first electromagnet 51a to the upper surface of the substrate W is H1, and the distance from the lower surface of the first electromagnet 51a to the upper surface of the central region electromagnet 52 is H2, the central region electromagnet 52 may be arranged at a position where the relationship of the following formula (3) holds.

[0044] 0 < H2 < H1 … (3)

[0045] Equation (3) indicates that the central area electromagnet 52 is not in contact with the first electromagnet 51a in the height direction, and is located closer to the placed substrate W than the first electromagnet 51a.

[0046] The central region electromagnet 52 arranged as described above can form a magnetic field line loop between itself and the fifth electromagnet 51e, for example, to form a magnetic field distribution that has a peak below the fifth electromagnet 51e while providing a sufficiently weak magnetic field vertically below the central region electromagnet 52. In other words, by appropriately adjusting the excitation currents to the first electromagnet 51a to the fifth electromagnet 51e and the central region electromagnet 52, the electromagnet excitation circuit 59 can form a magnetic field that can sufficiently reduce the electron density of plasma that becomes high in the central region of the plasma processing space 10s.

[0047] The plasma processing apparatus according to the embodiment is basically configured as described above, and its operation (plasma processing method) will be described below with reference to the graphs in Figures 4(A) and 4(B). Figure 4(A) is a graph showing the operation of the magnetic field generating unit 50 according to the first embodiment. Figure 4(B) is a graph showing the operation of the magnetic field generating unit according to a reference example. In the four vertically aligned graphs in Figures 4(A) and 4(B), the horizontal axis indicates the position from the center to the outer edge of the substrate W. Furthermore, the vertical axes of the four graphs indicate, from top to bottom, the magnetic field, electron density, sheath electric field, and tilting, respectively.

[0048] To facilitate understanding of the magnetic field generating unit 50 according to the first embodiment, we will first describe the relationship between the magnetic field distribution and tilting in the reference example shown in Fig. 4(B). This reference example illustrates the magnetic field, electron density, sheath electric field, and tilting when the magnetic field distribution is formed by the first electromagnet 51a to the fifth electromagnet 51e without the central region electromagnet 52.

[0049] The first electromagnet 51a to the fifth electromagnet 51e are supplied with an excitation current by the electromagnet excitation circuit 59, thereby forming a magnetic field distribution as shown in the top graph of Figure 4(B). Specifically, the magnetic field is weakest near the central axis of the substrate W (substrate support part 11). However, a certain amount of magnetic field component is also generated at the central axis of the substrate W, and the magnetic field gradually (approximately linearly) increases from this central axis toward the radially outward direction. The magnetic field then reaches a peak at the outer edge of the substrate W.

[0050] The electron density Ne in the plasma processing space 10s is affected by this magnetic field (magnetic flux B). However, during plasma generation, a high electron density Ne is inherently generated in the central region of the plasma processing space 10s. Therefore, even if the magnetic field at the center is weak, as in the magnetic field distribution described above, the increase in electron density Ne cannot be suppressed. As a result, as shown in the second graph of FIG. 4B, the electron density Ne is high near the central axis of the substrate W and decreases radially outward from the central axis. Then, once the electron density Ne is roughly flattened at a midpoint in the radial direction due to the magnetic field distribution, this flattened state is maintained up to the vicinity of the outer edge of the substrate W. Furthermore, the electron density Ne is slightly higher at the outer edge of the substrate W.

[0051] The shape of the sheath electric field S generated above the substrate W during plasma processing is affected by the plasma density, which is correlated with the electron density Ne in the plasma processing space 10s. Therefore, as shown in the third graph in Figure 4(B), the sheath electric field S has a bottom near the central axis of the substrate W and forms a gradient that increases radially outward from the center. The sheath electric field S then becomes roughly flattened midway in the radial direction and remains flat up to near the outer edge of the substrate W. At the outer edge of the substrate W, the sheath electric field S becomes slightly lower.

[0052] During etching processing, tilting occurs according to the shape of the sheath electric field S. The tilting inclination becomes larger in portions where the gradient of the sheath electric field S is large. Specifically, as shown in the fourth graph in Fig. 4(B) , tilting rises in a mountain-like shape from the central axis of the substrate W toward the outside in the radial direction. Then, the tilting becomes roughly flattened midway in the radial direction, and this flattened state is maintained up to the vicinity of the outer edge of the substrate W.

[0053] As described above, the magnetic field distribution without the central region electromagnet 52 according to the reference example cannot suppress tilting, particularly near the center of the substrate W. As a result, the etched substrate W will have contact holes that are inclined with respect to the thickness direction.

[0054] In contrast, the magnetic field generating unit 50 according to the first embodiment includes a central-zone electromagnet 52 in addition to the first to fifth electromagnets 51a to 51e. In this case, the control unit 2 controls the electromagnet excitation circuit 59 to supply excitation currents to the first to fifth electromagnets 51a to 51e and the central-zone electromagnet 52. As a result, the first to fifth electromagnets 51a to 51e and the central-zone electromagnet 52 can form a magnetic field distribution as shown in the top graph of FIG. 4A . Specifically, by forming a negative magnetic field using the central-zone electromagnet 52, the magnetic field is weakest near the central axis of the substrate W and is generally zero. Due to the influence of the central-zone electromagnet 52, the magnetic field distribution has a gradient that increases sharply from the central axis toward the radially outward direction. Furthermore, the magnetic field distribution switches to a gradually increasing gradient at a radial midpoint (e.g., at the boundary between Zone 1 and Zone 2). The magnetic field then reaches a peak at the outer edge of the substrate W.

[0055] The electron density Ne in the plasma processing space 10s is originally high in the central region, but the influence of the above-mentioned magnetic field (magnetic flux B) suppresses this increase in the central region. As a result, as shown in the second graph in Figure 4(A), the electron density Ne does not increase even near the central axis of the substrate W, but remains generally flat from the central axis toward the radially outward direction. This flat state is also maintained near the outer edge of the substrate W.

[0056] As shown in the third graph in Figure 4A, the sheath electric field S generated above the substrate W during plasma processing is affected by the above-mentioned electron density and is prevented from becoming lower near the central axis of the substrate W. Therefore, the sheath electric field S remains generally flat (without gradient) from the central axis of the substrate W outward in the radial direction. This flat state is also maintained near the outer edge of the substrate W.

[0057] The flat sheath electric field S maintains tilting during the etching process substantially constant, as shown in the fourth graph in Fig. 4A. In other words, since tilting hardly occurs radially outward from the central axis of the substrate W, ions generated in the plasma processing space 10s are attracted in a direction substantially perpendicular to the surface of the substrate W. As a result, contact holes extending linearly in the thickness direction are formed in the substrate W during the etching process.

[0058] As described above, the plasma processing apparatus 1 according to the embodiment can appropriately form a magnetic field distribution in the plasma processing space 10s and improve the uniformity and stability of the plasma processing by including the central region electromagnet 52. In particular, by using the central region electromagnet 52, which is an electromagnet, the magnetic field generating unit 50 can easily induce the magnetic field of Zone 0 by controlling the supply of excitation current.

[0059] Furthermore, the central region electromagnet 52 weakens the magnetic field in the central region of the plasma processing space 10s and forms a gradient in which the magnetic field increases sharply toward the radially outward direction, thereby smoothly guiding the electron density Ne in the horizontal direction. Also, since the central region electromagnet 52 overlaps with the first electromagnet 51a in a plan view, the angle of the gradient of the magnetic field distribution between the central region electromagnet 52 and the first electromagnet 51a (zone 1) can be made larger, thereby smoothly continuing the electron density Ne.

[0060] The plasma processing apparatus 1 of the present disclosure is not limited to the above embodiment and may take various modified forms. For example, the above description is of the plasma processing apparatus 1 that performs an etching process to form contact holes in the substrate W as a plasma process. However, the plasma processing apparatus 1 is not limited to an etching process, and may also perform other plasma processes such as a film formation process or a cleaning process.

[0061] Furthermore, for example, the magnet disposed inside and vertically below the first electromagnet 51a is not limited to being housed within the shower head 13, and may be disposed on a member disposed vertically above the shower head 13. Fig. 5 is a side cross-sectional view showing a magnetic field generating unit 50A and its surroundings according to a first modified example. For example, as in the first modified example shown in Fig. 5, the magnetic field generating unit 50A of the plasma processing apparatus 1A has a central region electromagnet 52 disposed on the top plate 16 vertically above the shower head 13.

[0062] Specifically, the plasma processing apparatus 1A has a shower head 13 fixed via an insulating fixing member 14, and a cooling plate 15 laminated on the shower head 13. The cooling plate 15 has a coolant flow path and the like inside, and removes heat from the shower head 13, the temperature of which increases with plasma processing. However, the cooling plate 15 does not necessarily have to be installed.

[0063] The plasma processing apparatus 1A has a configuration in which the upper part of the plasma processing chamber 10 is covered with a top plate 16. The top plate 16 closes the upper end of the side wall 10a and is grounded via the side wall 10a. A space 50s that performs an insulating function is formed between the cooling plate 15 and the top plate 16.

[0064] Furthermore, an electrode rod 35 connected to an external power source 30 is inserted into the center of the plasma processing chamber 10 so as to penetrate the top plate 16. The electrode rod 35 supplies power (such as a source RF signal or a second DC signal) to the showerhead 13. The electrode rod 35 is insulated from the top plate 16 by an insulating member 36 attached to the outer periphery. The processing gas discharged from the showerhead 13 is supplied, for example, via a passage provided in the electrode rod 35.

[0065] The magnetic field generating unit 50A of the plasma processing apparatus 1A is installed at a position (top plate 16) insulated from the shower head 13, which is the upper electrode. For example, the first electromagnet 51a to the fifth electromagnet 51e are arranged radially inside the top plate 16. Meanwhile, the central region electromagnet 52 is attached to the underside (space 50s) of the top plate 16. The central region electromagnet 52 is positioned more inward than the first electromagnet 51a and closer to the shower head 13 (substrate W), and surrounds the insulating member 36. The central region electromagnet 52 is connected to a power line 53 routed through a hole in the outer periphery of the top plate 16, thereby being electrically connected to an electromagnet excitation circuit 59.

[0066] As with the magnetic field generating unit 50 according to the above embodiment, the magnetic field generating unit 50A configured in this manner can also effectively generate a magnetic field distribution capable of flattening the sheath electric field using the central region electromagnet 52. In particular, by arranging the central region electromagnet 52 vertically above the shower head 13, the shower head 13 can be made thinner, thereby increasing the degree of freedom in layout. Furthermore, by providing each electromagnet 51 and the central region electromagnet 52 in a position insulated from the shower head 13, an appropriate magnetic field can be generated without being affected by the power used for plasma generation. Therefore, the plasma processing apparatus 1A can accurately perform plasma processing by utilizing the magnetic field generated by the magnetic field generating unit 50A.

[0067] 6 is a side cross-sectional view showing a magnetic field generating unit 50B and its surroundings according to the second modification. As shown in FIG. 6, the magnetic field generating unit 50B of the plasma processing apparatus 1B includes a magnet located inside and vertically below the first electromagnet 51a, housed within the cooling plate 15. Even in this case, the magnetic field generating unit 50B can effectively form a magnetic field distribution that flattens the sheath electric field.

[0068] Furthermore, the magnets arranged inside and vertically below the first electromagnet 51a are permanent magnets 55, rather than electromagnets. Therefore, the magnetic field generating unit 50B includes a first electromagnet 51a arranged at a first height and a permanent magnet 55 arranged at a second height different from the first height. The second height is smaller than the first height. In one embodiment, at least a portion of the permanent magnet 55 is arranged inside the first electromagnet 51a in a plan view. In one embodiment, the magnetic field generating unit 50B includes second to fifth electromagnets 51b to 51e arranged at the first height. The second electromagnet 51b is arranged outward from the first electromagnet 51a in a plan view. The third electromagnet 51c is arranged outward from the second electromagnet 51b in a plan view. The fourth electromagnet 51d is arranged outward from the third electromagnet 51c in a plan view. The fifth electromagnet 51e is arranged outward from the fourth electromagnet 51d in a plan view. By using the permanent magnets 55, the magnetic field generating unit 50B does not need to supply power to the magnets located inside and vertically below. As a result, the layout of the magnets, such as their installation positions, can be improved and costs can be reduced. The shape and magnetic force of the permanent magnets 55 can be designed appropriately based on the target magnetic field distribution.

[0069] In short, the magnet disposed inside and vertically below the first electromagnet 51a can be placed on any member, as long as it is above the substrate W placed on the substrate support 11. Furthermore, the type of magnet is not particularly limited, and any known magnet can be used, as long as it can form a target magnetic field distribution.

[0070] 7 is a diagram illustrating an example of the configuration of a capacitively coupled plasma processing system according to a second embodiment. The plasma processing system according to the second embodiment also 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 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 unit. The gas inlet unit is configured to introduce at least one process gas into the plasma processing chamber 10. The gas inlet unit includes a shower head 13.

[0071] The plasma processing apparatus 1 according to the second embodiment also includes a magnetic field generating unit 50C that is provided above the substrate support 11 across the plasma processing space 10s and generates a magnetic field in the plasma processing space 10s. The magnetic field generating unit 50C is provided vertically above the shower head 13, which is an upper electrode to which the RF power supply 31 (plasma generating unit) is connected. Specifically, the magnetic field generating unit 50C is installed on a top plate 16 that forms part of the ceiling of the plasma processing chamber 10.

[0072] 8 is a side cross-sectional view showing a magnetic field generation unit 50C according to the second embodiment. As shown in FIG. 8, the magnetic field generation unit 50C has a plurality of electromagnets 51 arranged along the horizontal direction. The magnetic field generation unit 50C according to the second embodiment also includes a magnet displacement unit 60 that can adjust the relative positions of the plurality of electromagnets 51 with respect to the plasma processing space 10s. The magnet displacement unit 60 has a plurality of elevating mechanisms 61 that hold each of the plurality of electromagnets 51 and can raise and lower the electromagnets 51 independently of one another.

[0073] Each electromagnet 51 has a yoke 56 and a coil 57 wound around the yoke 56. For example, the yoke 56 is formed in a concave shape that is open on the bottom side and surrounds the sides and ceiling, and holds the coil 57 within the concave space.

[0074] Each lifting mechanism 61 of the magnet displacement unit 60 includes a drive body 62 fixed to the lower surface of the top plate 16 and a movable shaft 63 protruding vertically downward from the drive body 62. Each electromagnet 51 is electrically connected to an electromagnet excitation circuit 59 (see FIG. 1 ) by, for example, wiring passing through the inside of the lifting mechanism 61 held by the electromagnet 51. Each lifting mechanism 61 is also connected to the control unit 2 via a driver (not shown) provided outside the plasma processing chamber 10. This allows the control unit 2 to independently raise and lower each lifting mechanism 61 and individually adjust the height position of each electromagnet 51.

[0075] The lifting mechanism 61 can be a well-known actuator capable of moving the movable shaft 63 back and forth. For example, the lifting mechanism 61 can have a motor and a gear mechanism inside the drive body 62, and can be configured to convert the rotational driving force of the motor into linear motion of the movable shaft 63 via the gear mechanism, thereby lifting and lowering the movable shaft 63. Alternatively, the lifting mechanism 61 may use a ball screw mechanism or a cylinder mechanism (hydraulic or pneumatic). The lifting mechanism 61 may also be configured to have a position detector such as an encoder that detects the position of the movable shaft 63, and to output the detection result of the position detector to the drive driver. This allows the magnet displacement unit 60 to perform feedback control when adjusting the electromagnet 51 to a target height position.

[0076] The movable shaft 63 projects linearly from the drive body 62 and holds the yoke 56 at its lower end. Therefore, each electromagnet 51 is suspended by each lifting mechanism 61 in the space 50s between the top plate 16 and the shower head 13.

[0077] 9 is a plan view of the magnetic field generating unit 50C and the magnet displacement unit 60 according to the second embodiment, viewed from above in the vertical direction. The electromagnets 51 are formed in an annular (ring-like) shape and are arranged concentrically around the central axis of the plasma processing chamber 10. The central axis of the plasma processing chamber 10 also corresponds to the central axis of the plasma processing space 10s, the substrate support 11, the shower head 13, and the like. The shower head 13 supplies gas to the gas diffusion chamber 13b via a shaft 17 along the central axis and high-frequency power to the head body below. In a side cross-sectional view, the electromagnets 51 are arranged parallel to the radial direction (horizontal direction) of the shower head 13 and at equal intervals.

[0078] For example, a pair (two) of lifting mechanisms 61 for lifting and lowering each electromagnet 51 are provided for each annular electromagnet 51. The magnet displacement unit 60 can vertically lift and lower each electromagnet 51 while maintaining its horizontal position by driving the pair of lifting mechanisms 61 at the same time using a drive driver. Note that the magnet displacement unit 60 may also include, in addition to the lifting mechanisms 61, a guide member (not shown) for guiding the lifting and lowering of the electromagnet 51 between the top plate 16 and the electromagnet 51. The number of lifting mechanisms 61 supporting each electromagnet 51 is not particularly limited and may be one or three or more.

[0079] The electromagnets 51 include, in order from the central axis of the plasma processing chamber 10 toward the radially outward direction, a first electromagnet 51 a, a second electromagnet 51 b, a third electromagnet 51 c, a fourth electromagnet 51 d, and a fifth electromagnet 51 e. In the illustrated example, the first electromagnet 51 a, the second electromagnet 51 b, the third electromagnet 51 c, the fourth electromagnet 51 d, and the fifth electromagnet 51 e have the same cross-sectional shape (width, thickness), but this cross-sectional shape may differ among the electromagnets 51. The cross-sectional shape of each electromagnet 51 may be designed as appropriate depending on the target magnetic field distribution formed by each electromagnet 51, etc.

[0080] 7, the diameter of the outer edge of the third electromagnet 51c is smaller than the diameter of the substrate W. Therefore, the first to third electromagnets 51a to 51c are provided at positions where they overlap the substrate W placed on the substrate support part 11 in a plan view. On the other hand, the diameter of the outer edge of the fourth electromagnet 51d is larger than the diameter of the substrate W and is set to, for example, approximately the same as the diameter of the outer edge of the ring assembly 112. Therefore, the fourth electromagnet 51d is provided at a position where it overlaps the ring assembly 112 placed on the substrate support part 11 in a plan view. The fifth electromagnet 51e, which is located outside the fourth electromagnet 51d, is provided at a position where it does not face the substrate support part 11 (ring assembly 112) in a plan view.

[0081] The coils of the first electromagnet 51a to the fifth electromagnet 51e are electrically connected to an electromagnet excitation circuit 59 via respective wirings. The electromagnet excitation circuit 59 supplies excitation currents to the first electromagnet 51a to the fifth electromagnet 51e based on commands from the control unit 2. The electromagnet excitation circuit 59 can adjust the amount of each excitation current supplied to the first electromagnet 51a to the fifth electromagnet 51e based on commands from the control unit 2. Furthermore, the electromagnet excitation circuit 59 can supply excitation currents to any combination (or individually) of the first electromagnet 51a to the fifth electromagnet 51e.

[0082] The magnetic field generating unit 50C generates an appropriate magnetic field in the plasma processing space 10s below the shower head 13 by supplying excitation currents to the electromagnets 51 from the electromagnet excitation circuit 59. The first to fifth electromagnets 51a to 51e work in conjunction with one another to generate a magnetic field in the plasma processing space 10s, with each electromagnet exerting the greatest influence on the magnetic field vertically below its installation position. Specifically, the first electromagnet 51a influences the magnetic field in Zone 1, which is located near the central axis of the plasma processing space 10s. The second electromagnet 51b influences the magnetic field in Zone 2, which is adjacent to Zone 1 radially outward. The third electromagnet 51c influences the magnetic field in Zone 3, which is adjacent to Zone 2 radially outward. The fourth electromagnet 51d influences the magnetic field in Zone 4, which is adjacent to Zone 3 radially outward. The fifth electromagnet 51e influences the magnetic field in Zone 5, which is adjacent to Zone 4 radially outward. A magnetic field distribution is formed in the plasma processing space 10s in which the magnetic fields of Zones 1 to 5 are mutually continuous.

[0083] 8, the plasma processing apparatus 1 preferably includes a sensor group 70 for measuring the influence of the magnetic field generating unit 50C on the plasma processing. Examples of the sensor group 70 include a magnetic sensor 71 capable of detecting magnetism (magnetic field) around each electromagnet 51, and an electric field sensor 72 capable of measuring electric field strength (electron density). While FIG. 8 illustrates a configuration including both the magnetic sensor 71 and the electric field sensor 72, the sensor group 70 may include only one of the magnetic sensor 71 and the electric field sensor 72.

[0084] The magnetic sensor 71 measures the magnitude and / or direction of the magnetic field generated by each electromagnet 51. For example, the magnetic sensor 71 is provided on the surface of each electromagnet 51 that is exposed from the yoke 56. Each magnetic sensor 71 measures the magnetic field of each of the multiple electromagnets 51 and transmits the measurement results to the control unit 2.

[0085] The electric field sensor 72 may be a field intensity meter that measures the electric field intensity between the top plate 16 and the shower head 13. For example, a plurality of electric field sensors 72 may be provided and distributed on the upper surface of the shower head 13. Each electric field sensor 72 measures the electric field intensity of the in-plane distribution of the shower head 13 and transmits the measurement results to the control unit 2.

[0086] The control unit 2 can adjust the height position of the electromagnet 51 or the magnitude of the magnetic field generated by the electromagnet 51 based on the measurement results of each magnetic sensor 71 and each electric field sensor 72 .

[0087] 10A to 10D are side views schematically illustrating examples of adjusting the height position of each electromagnet 51 of the magnetic field generating unit 50C. As shown in FIG. 10A, the magnetic field generating unit 50C can position each electromagnet 51 at a position away from the shower head 13 (vertically above the space 50s) using the magnet displacement unit 60. In this case, the distance between each electromagnet 51 and the plasma processing space 10s is reduced, thereby narrowing the magnetic field control range MF. Therefore, in the plasma processing apparatus 1, when magnetic field control is not required or when the effects of magnetic field control need to be reduced, the electromagnets 51 can be positioned as shown in FIG. 10A to perform plasma processing.

[0088] 10B, the magnetic field generating unit 50C can use the magnet displacement unit 60 to position each electromagnet 51 close to the shower head 13 (vertically below the space 50s). In this case, the magnetic flux of each electromagnet 51 increases as the electromagnet 51 approaches the plasma processing space 10s, thereby expanding the magnetic field control range MF. Therefore, when wide-area magnetic field control is required, the plasma processing apparatus 1 can perform plasma processing by arranging the electromagnets 51 as shown in FIG.

[0089] 10C, the magnetic field generating unit 50C can use the magnet displacement unit 60 to position the first electromagnet 51a to the fifth electromagnet 51e at positions that gradually increase in height from the center toward the periphery. That is, the first electromagnet 51a, which is closest to the center, is positioned close to the shower head 13, and the fifth electromagnet 51e, which is closest to the periphery, is positioned farther away from the shower head 13. This allows the plasma processing apparatus 1 to widen the control range MF of the magnetic field on the center side while narrowing the control range MF of the magnetic field on the periphery side. For example, the plasma processing apparatus 1 can adopt this configuration when it is desired to intensively control the magnetic field on the center side of the substrate W.

[0090] 10(D), the magnetic field generating unit 50C can use the magnet displacement unit 60 to position the first electromagnet 51a to the fifth electromagnet 51e at positions that gradually decrease from the center toward the periphery. That is, the first electromagnet 51a, which is located at the most center, is positioned away from the shower head 13, and the fifth electromagnet 51e, which is located at the most periphery, is positioned close to the shower head 13. This allows the plasma processing apparatus 1 to narrow the control range MF of the magnetic field control at the center while widening the control range MF of the magnetic field at the periphery. For example, the plasma processing apparatus 1 can adopt this configuration when it is desired to intensively control the magnetic field at the periphery of the substrate W.

[0091] In this way, the magnetic field generating unit 50C can adjust the magnetic field control range MF of the plasma processing space 10s by adjusting the height position of each electromagnet 51. The magnetic field generating unit 50C can adjust the height position of each electromagnet 51 according to various situations, thereby improving the uniformity of the in-plane distribution of plasma processing. Note that the height positions of the electromagnets 51 are not limited to being arranged in stages as shown in Figures 10(C) and 10(D). For example, the second electromagnet 51b and the third electromagnet 51c may be arranged at the same height, and the fourth electromagnet 51d and the fifth electromagnet 51e may be arranged at the same height, and the height positions may be changed by combining these.

[0092] FIG. 11(A) is a side view showing a schematic example of the arrangement of the electromagnets 51 when the electric field strength in the space 50s is high. FIG. 11(B) is a side view showing a schematic example of the arrangement of the electromagnets 51 when the electric field strength in the space 50s is low. FIG. 11(C) is a side view showing the risk of electromagnetic interference in the fixed electromagnets 51 of the magnetic field generating unit 50C' according to the reference example. Next, with reference to FIGS. 11(A) to 11(C), the arrangement of the electromagnets 51 will be described in further detail.

[0093] 11C shows a reference example in which the electromagnets 51 of a magnetic field generating unit 50C' are fixed close to the showerhead 13 in order to widen the magnetic field control range MF. In this case, for example, if the electromagnetic waves in the space 50s become stronger, the risk of electromagnetic interference (EMI) increases. For example, the electromagnetic interference may affect the electromagnet excitation circuit 59 that controls the electromagnets 51, potentially resulting in control errors, equipment failure, and the like.

[0094] To avoid this risk of electromagnetic interference, it is conceivable to fix each electromagnet 51 of the magnetic field generating unit 50C' at a position separated from the shower head 13. However, if each electromagnet 51 is placed at a position separated from the shower head 13, the control range MF of the magnetic field becomes narrow, and there is a possibility that the desired magnetic field may not be obtained.

[0095] On the other hand, the magnetic field generating unit 50C according to the second embodiment is provided with a magnet displacement unit 60, which makes each electromagnet 51 movable. This allows each electromagnet 51 to be positioned appropriately depending on the situation.

[0096] 11A , when the magnetic field generating unit 50C is in a condition where the risk of electromagnetic interference is high, the electromagnets 51 are positioned at a distance from the shower head 13. In this case, the control unit 2 can set the height position of each electromagnet 51 by measuring or estimating in advance the state of electromagnetic waves in the space 50s. For example, when the electric field strength measured by the electric field sensor 72 of the sensor group 70 is high, the control unit 2 positions each electromagnet 51 at a position a first distance away from the shower head 13. This can reduce the risk of electromagnetic interference for each electromagnet 51. Furthermore, for example, the control unit 2 can estimate the electromagnetic waves generated in the space 50s based on a plasma processing recipe and set the height position of each electromagnet 51.

[0097] On the other hand, when the electric field intensity measured by the electric field sensor 72 is weak, the control unit 2 places each electromagnet 51 at a second distance, which is shorter than the first distance, from the shower head 13, as shown in Fig. 11(B) . This allows the plasma processing apparatus 1 to widen the magnetic field control range MF by using each electromagnet 51 closer to the shower head 13 while reducing the risk of electromagnetic interference.

[0098] In this way, by providing the electromagnets 51 that can be raised and lowered, the plasma processing apparatus 1 can position the electromagnets 51 as close as possible to the shower head 13 while reducing the risk of electromagnetic interference, thereby widening the magnetic field control range MF. Therefore, for example, when a bias potential is applied from the power supply 30, the plasma processing apparatus 1 can effectively flatten the sheath electric field by controlling the magnetic field. As a result, the direction in which the active species of the plasma are attracted to the substrate W can be guided to be parallel to the thickness direction of the substrate W.

[0099] 12(A) is a diagram illustrating an example of the etching rate before adjusting the height position of each electromagnet. FIG. 12(B) is a diagram illustrating an example of manipulating the etching rate by adjusting the height position of each electromagnet. For ease of explanation, FIGS. 12(A) and 12(B) show an example in which the height position of each electromagnet 51 is adjusted while the current (power) supplied to each electromagnet 51 is maintained constant. However, in actual plasma processing, in addition to adjusting the height position of each electromagnet 51, the power (excitation current) supplied to each electromagnet 51 may of course be adjusted to promote uniformity in the etching rate.

[0100] The magnetic field generating unit 50C according to this embodiment can adjust the etching rate of the substrate W during plasma processing by changing the height position of each electromagnet 51. For example, as shown in Fig. 12A, when the height positions of the electromagnets 51 are the same, the etching rate is high on the central side and the outer periphery, while the etching rate is low on the intermediate side between the central side and the outer periphery. In other words, this is a state in which the in-plane distribution of the etching rate of the substrate W is non-uniform.

[0101] In this case, as shown in FIG. 12B , the magnetic field generating unit 50C adjusts the height positions of the second electromagnet 51 b and the third electromagnet 51 c of the electromagnets 51 so that they are closer to the shower head 13. By bringing the second electromagnet 51 b and the third electromagnet 51 c closer to the substrate W in this manner, the magnetic field distribution near those locations can be controlled to a strong magnetic field (or a weak magnetic field due to an opposite magnetic field). As a result, the etching rate applied to the substrate W is adjusted to a generally uniform state at the center, middle, and outer periphery. In other words, the plasma processing apparatus 1 can uniformize the in-plane distribution of the etching rate of the substrate W by independently adjusting the height positions of the electromagnets 51.

[0102] FIG. 13A is a diagram illustrating charge-up damage before adjusting the height positions of the electromagnets 51. FIG. 13B is a diagram illustrating the manipulation of charge-up damage by adjusting the height positions of the electromagnets 51. The magnetic field generating unit 50C according to the embodiment can adjust charge-up damage, which is damage that occurs on the surface of the substrate W during plasma processing, by changing the height positions of the electromagnets 51. For example, as shown in FIG. 13A, when the height positions of the electromagnets 51 are the same, assume that etching is performed on the substrate W in which the charge-up damage is large at the center and small at the middle and outer periphery. In other words, this is a state in which the in-plane distribution of charge-up damage on the substrate W is non-uniform.

[0103] In this case, as shown in FIG. 13B , the magnetic field generating unit 50C adjusts the height position of the first electromagnet 51a of the electromagnets 51 so that it is positioned close to the shower head 13. By bringing the first electromagnet 51a closer to the substrate W in this manner, the magnetic field distribution in the vicinity of that location can be controlled to a weak magnetic field by an opposite magnetic field. As a result, charge-up damage to the substrate W becomes roughly uniform on the central, intermediate, and outer periphery sides. In other words, by independently adjusting the height positions of the electromagnets 51, the plasma processing apparatus 1 can also uniformize charge-up damage during plasma processing.

[0104] The plasma processing apparatus 1 according to the second embodiment is basically configured as described above, and its operation (magnetic field control method) will be described below with reference to Fig. 14. Fig. 14 is a flowchart showing the plasma processing method of the plasma processing apparatus 1.

[0105] The control unit 2 of the plasma processing apparatus 1 performs plasma processing (etching) on ​​the substrate W by sequentially executing steps S101 to S105 shown in FIG.

[0106] The control unit 2 first determines the height position of each electromagnet 51 during plasma processing by referring to a plasma processing recipe (step S101). For example, the control unit 2 stores table information or a function indicating the relationship between the high-frequency power supplied by the shower head 13 and the height position of each electromagnet 51 by conducting experiments, simulations, or the like in advance. This allows the control unit 2 to easily set the height position of each electromagnet 51 based on the high-frequency power extracted from the recipe. Note that the control unit 2 may set the height position of each electromagnet 51 using other parameters (bias potential, gas type, temperature, pressure, etc.) in addition to the high-frequency power as appropriate. Alternatively, the control unit 2 may first estimate the electric field strength generated in the space 50s and then determine the height position of the electromagnet 51 based on the estimated electric field strength.

[0107] The height position of each electromagnet 51 is a position that can widen the magnetic field control range MF while minimizing the risk of electromagnetic interference as described above, and that promotes uniformity of the etching rate and the in-plane distribution of charge-up damage. The control unit 2 may allow the user to select which of these conditions to prioritize, and automatically determine the height position of each electromagnet 51 based on the condition with the highest priority. Alternatively, the plasma processing apparatus 1 may be configured so that the height position of each electromagnet 51 is set by user operation of the control unit 2.

[0108] Next, before the plasma processing, the control unit 2 operates the magnet displacement unit 60 via the driver based on the determined height position of each electromagnet 51 to adjust the height position of each electromagnet 51 (step S102). This allows the magnetic field generation unit 50C to position each electromagnet 51 at the set target height position.

[0109] The control unit 2 then calculates the magnetic field for controlling the plasma in the plasma processing space 10s and sets the power (excitation current) to be supplied to each of the electromagnets 51 based on the calculated value (step S103). The control unit 2 may recognize the magnetic field control range MF of the plasma processing space 10s based on the height position of each electromagnet 51 and calculate the power to be supplied to each electromagnet 51. For example, if the magnetic field control range MF is wide and the absolute value of the required magnetic field is large, a large first power value is set; if the magnetic field control range MF is wide and the absolute value of the required magnetic field is small, a second power value smaller than the first power value is set; if the magnetic field control range MF is narrow and the absolute value of the required magnetic field is large, a third power value even larger than the first power value is set; and if the magnetic field control range MF is narrow and the absolute value of the required magnetic field is small, a fourth power value smaller than the third power value is set.

[0110] After the various parameters have been set, the plasma processing apparatus 1 performs plasma processing under the control of the control unit 2 (step S104). In the plasma processing, the gas supply unit 20 supplies a processing gas into the plasma processing chamber 10, and the exhaust system 40 exhausts the gas inside the plasma processing chamber 10. In addition, the plasma processing apparatus 1 generates plasma in the plasma processing space 10s by supplying high-frequency power (a source RF signal) from the power supply 30, and further supplies a bias (e.g., a bias DC signal) to attract activated species of the plasma to the substrate W.

[0111] Then, during plasma processing, the control unit 2 controls the electromagnet excitation circuit 59 to supply the electric power set in step S103 to each electromagnet 51, thereby forming a desired magnetic field distribution in the plasma processing space 10s (step S105). As a result, the plasma processing apparatus 1 can perform etching processing on the substrate W with improved uniformity of the in-plane etching distribution.

[0112] Furthermore, the magnetic field generating unit 50C may perform control to change the height position of each electromagnet 51 during plasma processing. For example, the sensor group 70 may measure the electric field strength or magnetism generated in the space 50s, and if the risk of electromagnetic interference is high or if narrowing the magnetic field control range MF is not a problem, the height position of each electromagnet 51 may be raised (away from the shower head 13). Conversely, the sensor group 70 may measure the electric field strength or magnetism generated in the space 50s, and if the risk of electromagnetic interference is low or if it is desired to widen the magnetic field control range MF, the height position of each electromagnet 51 may be lowered (closer to the shower head 13).

[0113] Furthermore, the magnetic field generating unit 50C may individually adjust the height position of each electromagnet 51. For example, the control unit 2 estimates the electron density or sheath electric field generated in the plasma processing space 10s based on the magnetism (magnetic field) measured by the magnetic sensor 71, and changes the height position of each electromagnet 51 so that this sheath electric field becomes approximately flat. This makes it possible to effectively control tilting when attracting active species of plasma to the substrate W, and to perform etching parallel to the thickness direction of the substrate W.

[0114] As described above, the plasma processing apparatus 1 according to the second embodiment can adjust the magnetic field control range MF, reduce the risk of electromagnetic interference, and promote uniformity of the etching rate and charge-up damage by displacing each electromagnet 51 of the magnetic field generating unit 50C. As a result, the plasma processing apparatus 1 and the plasma processing method can accurately perform plasma processing such as etching on the substrate W, improve the uniformity and stability of the plasma processing, and increase the quality of the substrate W.

[0115] The plasma processing apparatus 1 according to the present disclosure is not limited to the above embodiment and may be modified in various ways. For example, the magnetic field generating unit 50C is not limited to using electromagnets 51 as the multiple magnets to be displaced, and may use permanent magnets. Even when permanent magnets are used, an appropriate magnetic field distribution (magnetic field control range MF) can be formed by displacing each magnet using the magnet displacement unit 60. Furthermore, although the second embodiment does not include the central region electromagnet 52 of the magnetic field generating unit 50 according to the first embodiment, this central region electromagnet 52 may also be included. If the magnetic field generating unit 50C includes the central region electromagnet 52, the central region electromagnet 52 may be immovably fixed to the shower head 13 or the cooling plate 15, or the central region electromagnet 52 may be raised and lowered by the lifting mechanism 61.

[0116] 15 is a side cross-sectional view showing a magnetic field generator 50D according to a third modification. The magnetic field generator 50D according to the third modification differs from the magnetic field generator 50C, which independently displaces each electromagnet 51, in that it includes a magnet displacement unit 60A that displaces the height positions of the electromagnets 51 as a whole. Thus, even though the magnetic field generator 50D displaces each electromagnet 51 as a whole, it can still achieve effects such as adjusting the magnetic field control range MF and reducing the risk of electromagnetic interference. Furthermore, the magnet displacement unit 60A can be configured such that the holder 64 that holds the electromagnets 51 together is raised and lowered by the lifting mechanism 61, simplifying the structure and reducing installation costs.

[0117] 15 shows an example in which the holder 64 holds the electromagnets 51 in a horizontally aligned state, but the holder 64 may hold the electromagnets 51 in a state in which the height positions of the electromagnets 51 have been adjusted in advance. As an example, the magnetic field generating unit 50D may have a configuration in which the first electromagnet 51a on the central side is located close to the shower head 13, and the second electromagnet 51b to the fifth electromagnet 51e on the outer sides of the first electromagnet 51a are gradually spaced apart from the shower head 13.

[0118] The above-disclosed embodiments include, for example, the following aspects.

[0119] [Supplementary Note 1] A plasma processing apparatus comprising: a plasma processing chamber having a plasma processing space therein; a substrate support provided inside the plasma processing chamber and supporting a substrate; a plasma generation unit provided inside the plasma processing chamber and for generating plasma in the plasma processing space; and a magnetic field generation unit provided above the substrate support and for generating a magnetic field in the plasma processing space, wherein the magnetic field generation unit includes a plurality of electromagnets arranged in a horizontal direction, and a magnet provided in a position closer to the substrate support unit than an electromagnet of the plurality of electromagnets that is closest to a central axis of the substrate support unit.

[0120] [Supplementary Note 2] The plasma processing apparatus according to Supplementary Note 1, further comprising: a shower head that discharges a processing gas into the plasma processing space; and the magnet is attached to the shower head or to a member that is provided vertically above the shower head.

[0121] [Supplementary Note 3] The plasma processing apparatus according to Supplementary Note 2, wherein the showerhead is an upper electrode that generates the plasma when power is supplied thereto, and the electromagnets and the magnet are provided at positions insulated from the showerhead.

[0122] [Supplementary Note 4] The plasma processing apparatus according to any one of Supplementary Notes 1 to 3, wherein the magnet cooperates with the plurality of electromagnets to make the magnetic field weakest in a central region of the plasma processing space and form a magnetic field distribution having a gradient in which the magnetic field suddenly increases radially outward from the central region of the plasma processing space.

[0123] [Supplementary Note 5] The plasma processing apparatus according to any one of Supplementary Notes 1 to 4, wherein the magnet overlaps with an electromagnet of the plurality of electromagnets that is positioned closest to a central axis of the substrate support part in a plan view.

[0124] [Supplementary Note 6] The plasma processing apparatus according to any one of Supplementary Notes 1 to 5, wherein the magnet is an electromagnet that generates a magnetic field in the plasma processing space based on the supply of an excitation current.

[0125] [Supplementary Note 7] The plasma processing apparatus according to any one of Supplementary Notes 1 to 5, wherein the magnet is a permanent magnet that maintains a constant magnetic force.

[0126] [Supplementary Note 8] A plasma processing apparatus including: a plasma processing chamber having a plasma processing space therein; a plasma generating unit that generates plasma in the plasma processing space; and a magnetic field generating unit that is provided vertically above the plasma processing space and generates a magnetic field in the plasma processing space, wherein the magnetic field generating unit includes: a plurality of magnets that are concentrically arranged with respect to one another in a plan view; and a magnet displacement unit that can adjust the relative positions of the plurality of magnets with respect to the plasma processing space.

[0127] [Supplementary Note 9] The plasma processing apparatus according to Supplementary Note 8, further comprising a control unit that controls the magnet displacement unit, wherein the control unit sets target height positions of the plurality of magnets and operates the magnet displacement unit to position the plurality of magnets at the target height positions.

[0128] [Supplementary Note 10] The plasma processing apparatus according to Supplementary Note 9, wherein each of the plurality of magnets is an electromagnet that forms a magnetic field based on a current from an electromagnet excitation circuit, and the control unit sets the target height positions of the plurality of magnets to positions that expand the control range of the magnetic field by the plurality of magnets while reducing the risk of electromagnetic interference to the plurality of magnets based on a plasma processing recipe.

[0129] [Supplementary Note 11] The plasma processing apparatus according to Supplementary Note 8 or 9, further comprising a sensor that measures at least one of an electric field intensity and a magnetism around the plurality of magnets, and the control unit operates the magnet displacement unit to adjust height positions of the plurality of magnets based on a detection result of the sensor.

[0130] [Supplementary Note 12] The plasma processing apparatus according to any one of Supplementary Notes 8 to 11, wherein the plasma generation unit includes a shower head that supplies a processing gas to the plasma processing space, and the magnet displacement unit is fixed to a ceiling plate of the plasma processing chamber and moves the plurality of magnets closer to or farther away from the shower head in a space between the ceiling plate and the shower head.

[0131] [Supplementary Note 13] The plasma processing apparatus according to any one of Supplementary Notes 1 to 12, wherein the magnet displacement unit includes a plurality of lifting mechanisms that independently lift and lower each of the plurality of magnets.

[0132] [Supplementary Note 14] The plasma processing apparatus according to any one of Supplementary Notes 1 to 13, wherein the magnet displacement unit includes a lifting mechanism that lifts and lowers the plurality of magnets together.

[0133] The plasma processing apparatus 1 according to the embodiment disclosed herein is illustrative in all respects and is not limiting. The embodiment can be modified and improved in various ways without departing from the scope and spirit of the appended claims. The matters described in the above-described embodiments can be configured in other ways as long as they are not inconsistent, and can be combined as long as they are not inconsistent.

[0134] The substrate processing apparatus of the present disclosure can be applied to any type of apparatus, including atomic layer deposition (ALD) apparatus, capacitively coupled plasma (CCP), inductively coupled plasma (ICP), radial line slot antenna (RLSA), electron cyclotron resonance plasma (ECR), and helicon wave plasma (HWP).

[0135] This application claims priority to Japanese Patent Application No. 2024-130128, a basic application filed on August 6, 2024 with the Japan Patent Office, and Japanese Patent Application No. 2025-006347, a basic application filed on January 16, 2025 with the Japan Patent Office, the entire contents of which are incorporated herein by reference.

[0136] REFERENCE SIGNS LIST 1 Plasma processing apparatus 10 Plasma processing chamber 10s Plasma processing space 11 Substrate support 31 RF power supply 50, 50A, 50B Magnetic field generating unit 51 Electromagnet 52 Central region electromagnet 55 Permanent magnet W Substrate

Claims

1. A plasma processing apparatus comprising: a plasma processing chamber having a plasma processing space therein; a substrate support section provided inside the plasma processing chamber and supporting a substrate; a plasma generation section provided inside the plasma processing chamber and supporting a substrate; a plasma generation section provided above the substrate support section and generating a magnetic field in the plasma processing space; and a magnetic field generation section provided above the substrate support section and generating a magnetic field in the plasma processing space, wherein the magnetic field generation section includes a plurality of electromagnets arranged horizontally, and a magnet provided in a position inward of the electromagnet of the plurality of electromagnets that is closest to the central axis of the substrate support section and in close proximity to the substrate support section.

2. The plasma processing apparatus according to claim 1, further comprising a shower head that discharges processing gas into the plasma processing space, and the magnet is attached to the shower head or to a member that is provided vertically above the shower head.

3. The plasma processing apparatus according to claim 2, wherein the showerhead is an upper electrode that generates the plasma when power is supplied thereto, and the plurality of electromagnets and the magnet are provided at positions insulated from the showerhead.

4. A plasma processing apparatus according to any one of claims 1 to 3, wherein the magnet cooperates with the plurality of electromagnets to form a magnetic field distribution having a gradient such that the magnetic field is weakest in a central region of the plasma processing space and the magnetic field suddenly increases radially outward from the central region of the plasma processing space.

5. The plasma processing apparatus according to any one of claims 1 to 3, wherein the magnet overlaps, in plan view, an electromagnet among the plurality of electromagnets that is positioned closest to the central axis of the substrate support part.

6. The plasma processing apparatus according to any one of claims 1 to 3, wherein the magnet is an electromagnet that generates a magnetic field in the plasma processing space based on the supply of an excitation current.

7. The plasma processing apparatus according to any one of claims 1 to 3, wherein the magnet is a permanent magnet that maintains a constant magnetic force.

8. A plasma processing apparatus comprising: a plasma processing chamber having a plasma processing space therein; a plasma generation unit that generates plasma in the plasma processing space; and a magnetic field generation unit that is provided vertically above the plasma processing space and generates a magnetic field in the plasma processing space, wherein the magnetic field generation unit comprises: a plurality of magnets that are arranged concentrically with respect to one another in a planar view; and a magnet displacement unit that can adjust the relative positions of the plurality of magnets with respect to the plasma processing space.

9. The plasma processing apparatus according to claim 8, further comprising a control unit that controls the magnet displacement unit, wherein the control unit sets target height positions for the plurality of magnets and operates the magnet displacement unit to position the plurality of magnets at the target height positions.

10. The plasma processing apparatus of claim 9, wherein each of the plurality of magnets is an electromagnet that forms a magnetic field based on a current from an electromagnet excitation circuit, and the control unit sets the target height position of the plurality of magnets to a position that expands the control range of the magnetic field by the plurality of magnets while reducing the risk of electromagnetic interference experienced by the plurality of magnets based on a plasma processing recipe.

11. A plasma processing apparatus as described in claim 9, further comprising a sensor for measuring at least one of the electric field strength and magnetic field around the plurality of magnets, and the control unit operates the magnet displacement unit to adjust the height positions of the plurality of magnets based on the detection results of the sensor.

12. The plasma processing apparatus according to any one of claims 8 to 11, wherein the plasma generation unit includes a shower head that supplies processing gas to the plasma processing space, and the magnet displacement unit is fixed to a ceiling plate of the plasma processing chamber and moves the plurality of magnets closer to or farther away from the shower head in the space between the ceiling plate and the shower head.

13. The plasma processing apparatus according to any one of claims 8 to 11, wherein the magnet displacement unit includes a plurality of lifting mechanisms that independently lift and lower each of the plurality of magnets.

14. The plasma processing apparatus according to any one of claims 8 to 11, wherein the magnet displacement unit includes a lifting mechanism that lifts and lowers the plurality of magnets as a unit.

Images