Substrate Processing Method and Substrate Processing Apparatus

Abstract

To provide a substrate processing method capable of suppressing generation of a nonuniform CD (critical Dimension) enlarged area even after the middle of etching, and a substrate processing device.SOLUTION: A substrate processing method is a method for substrate processing in a substrate processing device. The substrate processing device comprises: a chamber; a substrate support part configured to support a substrate in the chamber; an upper electrode opposed to the center of the substrate; and a plurality of electromagnets disposed radially with respect to the center of the upper electrode. The substrate processing method includes the steps of: selecting polarity change patterns of the plurality of electromagnets during etching; and generating plasma from a process gas supplied into the chamber and etching the substrate based on the polarity change patterns.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] Conventionally, in high aspect ratio etching of a film formed on a substrate, in order to obtain a vertical sidewall shape, it is known to control ions (charged particles) and neutral etchants (Cold Radical). Further, in order to easily change the distribution of the plasma density in the processing space, it has been proposed to arrange an electromagnet outside the upper electrode and control the magnetic poles of the electromagnet (Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present disclosure provides a substrate processing method and a substrate processing apparatus capable of suppressing the occurrence of a non-uniform CD (Critical Dimension) expansion region even in the latter half of etching.

Means for Solving the Problems

[0005] A substrate processing method according to an aspect of the present disclosure is a substrate processing method in a substrate processing apparatus, the substrate processing apparatus including a chamber, a substrate support portion configured to support a substrate in the chamber, an upper electrode facing the center of the substrate, and a plurality of electromagnets arranged radially with respect to the center of the upper electrode, the method including a step of selecting a polarity change pattern of the plurality of electromagnets during etching, and a step of generating plasma from a processing gas supplied into the chamber and etching the substrate based on the polarity change pattern.

Effects of the Invention

[0006] According to the present disclosure, it is possible to suppress the occurrence of a non-uniform CD expansion region even after the middle stage of etching.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0008] Hereinafter, embodiments of a substrate processing method and a substrate processing apparatus to be disclosed will be described in detail with reference to the drawings. Note that the disclosed technology is not limited by the following embodiments.

[0009] As described above, when controlling ions and neutral etchants to obtain a vertical sidewall shape, the ions have contributed to the rectangularization of the bottom (Btm) shape by controlling the ion angular distribution to be narrow. Also, the neutral etchant has contributed to the increase in bottom CD in combination with the sidewall protection gas. However, when further high aspect ratios are required, ions rebounded by the mask are concentrated and incident on the diagonal sidewalls, resulting in a non-uniform CD expansion region, that is, bowing (1 st , 2 nd , …) may occur. The non-uniform CD expansion region begins to manifest after the middle stage of etching when the hard mask starts to be etched and exhibits a facet shape. Therefore, it is expected to suppress the occurrence of non-uniform CD expansion regions even after the middle stage of etching.

[0010] [Configuration of Plasma Processing System] The configuration example of a plasma processing system will be described below. FIG. 1 is a diagram showing an example of a plasma processing system according to an embodiment of the present disclosure. As shown in FIG. 1, the plasma processing system includes a capacitively coupled plasma processing apparatus 1 and a control unit 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 unit 11 and a gas introduction unit. The gas introduction unit is configured to introduce at least one processing gas into the plasma processing chamber 10. The gas introduction unit includes a shower head 13. The substrate support unit 11 is disposed in the plasma processing chamber 10. The shower head 13 is disposed above the substrate support unit 11. In one embodiment, the shower head 13 constitutes at least a part of the ceiling of the plasma processing chamber 10. The plasma processing chamber 10 has a plasma processing space 10s defined by the shower head 13, the side wall 10a of the plasma processing chamber 10, and the substrate support unit 11. The plasma processing chamber 10 has at least one gas supply port for supplying at least one processing gas to the plasma processing space 10s and at least one gas discharge port for discharging gas from the plasma processing space 10s. The plasma processing chamber 10 is grounded. The shower head 13 and the substrate support unit 11 are electrically insulated from the housing of the plasma processing chamber 10.

[0011] The substrate support unit 11 includes a main body 111 and a ring assembly 112. The main body 111 has a central region 111a for supporting the substrate W and an annular region 111b for supporting the ring assembly 112. A wafer is an example of the 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 referred to as a substrate support surface for supporting the substrate W, and the annular region 111b is also referred to as 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 other members surrounding the electrostatic chuck 1111, such as an annular electrostatic chuck or an annular insulating member, may have the annular region 111b. In this case, the ring assembly 112 may be disposed on the annular electrostatic chuck or the annular insulating member, or may be disposed on both the electrostatic chuck 1111 and the annular insulating member. Also, 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 referred to as a bias electrode. Note that the conductive member of the base 1110 and the at least one RF / DC electrode may function as a plurality of lower electrodes. Also, the electrostatic electrode 1111b may function as a lower electrode. Accordingly, the substrate support portion 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 ring is formed of a conductive material or an insulating material, and the cover ring is formed of an insulating material.

[0014] Further, the substrate support portion 11 may include a temperature control 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 control module may include a heater, a heat transfer medium, a flow path 1110a, or a combination thereof. A heat transfer fluid such as brine or gas flows through the flow path 1110a. In one embodiment, the flow path 1110a is formed in the base 1110, and one or more heaters are disposed in the ceramic member 1111a of the electrostatic chuck 1111. Further, the substrate support portion 11 may include a heat transfer gas supply portion 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 shower head 13 is configured to introduce at least one process gas from the gas supply unit 20 into the plasma processing space 10s. The shower head 13 has at least one gas supply port 13a, at least one gas diffusion chamber 13b, and a plurality of gas introduction ports 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 plurality of gas introduction ports 13c. Further, the shower head 13 includes at least one upper electrode. Note that the gas introduction portion may include, in addition to the shower head 13, one or more side gas injectors (SGI) attached to one or more openings formed in the side wall 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 the corresponding gas source 21 to the shower head 13 via the corresponding flow controller 22. Each flow controller 22 may include, for example, a mass flow controller or a pressure-controlled flow controller. Further, the gas supply unit 20 may include one or more flow modulation devices that modulate or pulse the flow rate of 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. Thereby, plasma is formed from at least one processing gas supplied to the plasma processing space 10s. Accordingly, the RF power supply 31 can function as at least a part of a plasma generation unit configured to generate plasma from one or more processing gases in the plasma processing chamber 10. Also, by supplying a bias RF signal to at least one lower electrode, a bias potential is generated on the substrate W, and the ion component in the formed plasma can be drawn into the substrate W.

[0018] In one embodiment, the RF power supply 31 includes a first RF generation unit 31a and a second RF generation unit 31b. The first RF generation unit 31a is 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 generation unit 31a may be configured to generate a plurality of 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 generation unit 31b is coupled to at least one lower electrode via at least one impedance matching circuit and is configured to generate a bias RF signal (bias RF power). The frequency of the bias RF signal may be the same as or different from the frequency of the source RF signal. In one embodiment, the bias RF signal has a frequency lower than the frequency of the source RF signal. In one embodiment, the bias RF signal has a frequency in the range of 100 kHz to 60 MHz. In one embodiment, the second RF generation unit 31b may be configured to generate a plurality of bias RF signals having different frequencies. The generated one or more bias RF signals are supplied to at least one lower electrode. Also, in various embodiments, at least one of the source RF signal and the bias RF signal may be pulsed.

[0020] Further, the power supply 30 may include a DC power supply 32 coupled to the plasma processing chamber 10. The DC power supply 32 includes a first DC generation unit 32a and a second DC generation unit 32b. In one embodiment, the first DC generation unit 32a is connected to at least one lower electrode and is configured to generate a first DC signal. The generated first bias DC signal is applied to at least one lower electrode. In one embodiment, the second DC generation unit 32b is connected to at least one upper electrode and is configured to generate a second DC signal. The generated second DC signal is applied to 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 pulse waveform that is rectangular, trapezoidal, triangular, or a combination thereof. In one embodiment, a waveform generation unit for generating a sequence of voltage pulses from a DC signal is connected between the first DC generation unit 32a and at least one lower electrode. Accordingly, the first DC generation unit 32a and the waveform generation unit constitute a voltage pulse generation unit. When the second DC generation unit 32b and the waveform generation unit constitute a voltage pulse generation unit, the voltage pulse generation unit is connected to at least one upper electrode. The voltage pulses may have a positive polarity or a negative polarity. Also, the sequence of voltage pulses may include one or more positive-polarity voltage pulses and one or more negative-polarity voltage pulses within one period. Note that the first and second DC generation units 32a and 32b may be provided in addition to the RF power supply 31, or the first DC generation unit 32a may be provided in place of the second RF generation unit 31b.

[0022] The exhaust system 40 can be connected to, for example, a gas outlet 10e provided at the bottom of the plasma processing chamber 10. The exhaust system 40 may include a pressure regulating valve and a vacuum pump. The pressure in the plasma processing space 10s is adjusted by the pressure regulating valve. The vacuum pump may include a turbo molecular pump, a dry pump, or a combination thereof.

[0023] A plurality of electromagnets 50 are arranged substantially radially on the upper surface of the shower head 13 including the upper electrode, on the side opposite to the plasma processing space 10s. The electromagnet 50 has a rod-shaped yoke 50a made of iron core and a coil 50b made of a wire wound around the side surface of the yoke 50a with both ends drawn out. The electromagnet 50 can arbitrarily change the total magnetic flux and the direction of the magnetic flux generated by the electromagnet 50 by controlling the value and direction of the current flowing through the coil 50b by a controller (not shown). Note that, at the initial stage of etching, a current for canceling the bias magnetic field due to the hysteresis of the yoke 50a is passed through the electromagnet 50, and it is controlled so as not to generate a magnetic field.

[0024] The plurality of electromagnets 50 are divided into, for example, a central portion opposing group 51, a peripheral portion opposing group 52, and an outer opposing group 53. The central portion opposing group 51 includes electromagnets 50 that oppose the center of the substrate W. The peripheral portion opposing group 52 includes a plurality of electromagnets 50 that are arranged in an annular shape with respect to the center of the shower head 13 (upper electrode) that opposes the center of the substrate W and that oppose the peripheral portion of the substrate W. The outer opposing group 53 includes a plurality of electromagnets 50 that are arranged in an annular shape with respect to the center of the shower head 13 (upper electrode) and that are arranged outside the peripheral portion opposing group 52 and do not oppose the substrate W. Note that a plurality of electromagnets 50 may also be arranged between the central portion opposing group 51 and the peripheral portion opposing group 52, and between the peripheral portion opposing group 52 and the outer opposing group 53. Further, the central portion opposing group 51 may include a plurality of electromagnets 50.

[0025] In the plasma processing apparatus 1, for example, the direction of the current flowing through the coil 50b of each electromagnet 50 is controlled so that the poles on the plasma processing space 10s side of each electromagnet 50 in the peripheral portion opposing group 52 are all the same. Further, for example, the direction of the current flowing through the coil 50b of each electromagnet 50 is controlled so that the poles on the plasma processing space 10s side of each electromagnet 50 in the outer opposing group 53 are all the same. Furthermore, in the plasma processing apparatus 1, for example, in adjacent electromagnets 50 or in a set of a plurality of electromagnets 50 adjacent to one electromagnet 50, control is performed to change the polarity during the etching process based on the selected polarity change pattern.

[0026] The control unit 2 processes computer-executable instructions for causing the plasma processing apparatus 1 to execute various processes described in the present disclosure. The control unit 2 may be configured to control each element of the plasma processing apparatus 1 so as to execute the various processes described herein. In one embodiment, part or all of the control unit 2 may be included in the plasma processing apparatus 1. The control unit 2 may include a processing unit 2a1, a storage unit 2a2, and a communication interface 2a3. The control unit 2 is realized, for example, by a computer 2a. The processing unit 2a1 may be configured to read a program from the storage unit 2a2 and perform various control operations by executing the read program. This program may be stored in the storage unit 2a2 in advance, or may be acquired via a medium when necessary. The acquired program is stored in the storage unit 2a2 and read from the storage unit 2a2 by the processing unit 2a1 and executed. The medium may be various storage media readable by the computer 2a, or may be a communication line connected to the communication interface 2a3. The processing unit 2a1 may be a CPU (Central Processing Unit). The storage unit 2a2 may include a RAM (Random Access Memory), a ROM (Read Only Memory), an HDD (Hard Disk Drive), an SSD (Solid State Drive), or a combination thereof. The communication interface 2a3 may communicate with the plasma processing apparatus 1 via a communication line such as a LAN (Local Area Network).

[0027] [Elements of verticalization of sidewall shape] Here, with reference to FIG. 2, the elements of verticalization of the sidewall shape in high aspect ratio (HAR) etching will be described. FIG. 2 is a diagram showing an example of the elements of verticalization of the sidewall shape. States 60 to 62 shown in FIG. 2 show the state changes of the sidewalls of the holes when conventional ions and neutral etchants are controlled. Further, state 63 shows the state change of the sidewalls of the holes when the normal direction of the ions in the present embodiment is precessed.

[0028] State 60 represents a state in which, in the etching of the etched film 70 through the opening 72 defined by the mask 71, the shape of the hole 74 is gradually changed from a tapered shape to a vertical shape by ions 73 with high ion energy (Ei) and ion flux (Γi). State 61 represents a state in which the bottom CD 76 is enlarged by over-etching (OE) with the neutral etchant 75 while protecting the side walls of the hole 74. State 62 represents a state in which ions 77 are rebounded by the faceted mask 71a as the etching progresses, and the ions 77 are incident concentratedly on the side walls in the diagonal direction of the hole 74 as shown by the trajectories 78a and 78b, and discrete CD enlargement regions (Bow) 79a and 79b are generated in the depth direction.

[0029] On the other hand, in state 63, since the incident angle of ions 77a changes due to the precession motion in the normal direction, even if the ions 77a are rebounded by the mask 71a, they do not incident concentratedly on specific locations on the side walls of the hole 74a as shown by the trajectories 78c to 78e. Therefore, the generation of the CD enlargement region can be suppressed on the side walls of the hole 74a. In the present embodiment, as shown in state 63, the generation of the CD enlargement region is suppressed by causing the normal direction of the ions 77a to precess by the magnetic field of the electromagnet 50.

[0030] [Distribution and Control of Electron Density] Next, with reference to FIGS. 3 to 6, the distribution and control of the electron density (Ne) in the plasma processing space 10s will be described. FIG. 3 is a diagram showing an example of the magnetic field generated in the plasma processing space. FIG. 4 is a diagram showing an example of a set of electromagnets that perform polarity change as viewed from the lower surface side of the shower head. In FIG. 4, the electromagnet 50 is shown in a transmissive manner.

[0031] As shown in FIG. 3, in the plasma processing apparatus 1, for example, the magnetic pole on the plasma processing space 10s side of the electromagnet 50 in the central portion facing group 51 is set to the N pole, and the magnetic poles on the plasma processing space 10s side of the respective electromagnets 50 in the peripheral portion facing group 52 and the outer side facing group 53 are set to the S pole. Then, a magnetic field B is generated radially from the central portion facing group 51 toward the peripheral portion facing group 52 and the outer side facing group 53. At this time, since an electric field E is generated in the plasma processing space 10s, electrons in the plasma processing space 10s are drifted by receiving a Lorentz force caused by the electric field E and the magnetic field B. Specifically, in FIG. 4, an electric field E is generated from the front to the back, and a magnetic field B is generated radially with respect to the center of the shower head 13 (upper electrode). For this reason, electrons receive an acceleration in the tangential direction of the circumference of a circle concentric with the center of the shower head 13 (upper electrode) and swirl along a circular electron trajectory D in accordance with Fleming's left hand rule. At this time, the swirling electrons collide with molecules and atoms of the processing gas in the plasma processing space 10s to generate plasma. As a result, an annular plasma is generated along the circular electron trajectory D.

[0032] Here, when the intensity of the magnetic field B is increased by controlling a specific electromagnet 50, the velocity of the drift motion of electrons decreases, and the electron density at the location corresponding to the specific electromagnet 50 increases. That is, when the electron density (Ne) is likened to a table cross, by creating irregularities (changes in sheath thickness) at the positions of the respective electromagnets 50, it is possible to locally realize an inclination in an arbitrary angle and direction. That is, the incident angle of ions based on the distribution of the electron density can be controlled by the electromagnet 50. In addition, at the location where the electron density has increased, the chance of collision between electrons and molecules and atoms of the processing gas increases, so the plasma density increases.

[0033] To control the electron density in the in-plane (two-dimensional) of the substrate W, a plurality of electromagnets 50 are divided into a radial direction and an azimuth direction, and the electron density may be controlled by a phase difference. Thereby, the normal direction (incident angle) of the ions can be precessed. Therefore, in the present embodiment, for example, a set 80 is provided of the electromagnets 50 of the central portion facing group 51 and the electromagnets 50 of the peripheral portion facing group 52, which are adjacent electromagnets 50. Further, for example, a set 81 is provided of the electromagnets 50 of the peripheral portion facing group 52 and the electromagnets 50 of the outer facing group 53, which is a set of a plurality of adjacent electromagnets 50 with one electromagnet 50. Note that a plurality of sets 80 and 81 are provided in the circumferential direction. Also, the sets 80 and 81 may be provided respectively, or only one of the set 80 and the set 81 may be provided. Furthermore, since the number of the plurality of electromagnets 50 shown in FIG. 4 is an example, the electromagnets 50 may be arranged over the entire area of the shower head 13, and any adjacent electromagnets 50 may be set as the set 80, or a plurality of adjacent electromagnets 50 with any one electromagnet 50 may be set as the set 81. And to control the electron density by a phase difference, the polarity of the electromagnet 50 is changed in each of the plurality of sets 80 and 81.

[0034] FIG. 5 is a diagram showing an example of a polarity change pattern of the electromagnet. Note that the polarity shown in FIG. 5 is as viewed from the lower surface side of the shower head 13, similar to FIG. 4. The polarity change patterns 150 and 160 shown in FIG. 5 are each an example of a polarity change pattern corresponding to the sets 80 and 81 of the electromagnets 50 described above. The polarity change pattern 150 is a pattern in which, in the adjacent electromagnets 50 of the set 80, a state 151 in which one is an N pole and the other is an S pole and a state 152 in which the N pole and the S pole are interchanged are repeated. That is, the polarity change pattern 150 is an example of a pattern in which the polarities of adjacent electromagnets 50 among the plurality of electromagnets 50 are alternately changed.

[0035] The polarity change pattern 160 is a pattern in which, among the four electromagnets 50 of the set 81, two adjacent electromagnets 50 have the same polarity and the polarity is changed so as to rotate. In the polarity change pattern 160, in state 161, in FIG. 5, the upper two electromagnets 50 are S poles and the lower two electromagnets 50 are N poles. In state 162, in FIG. 5, the two electromagnets 50 on the right side are S poles and the two electromagnets 50 on the left side are N poles. In state 163, in FIG. 5, the lower two electromagnets 50 are S poles and the upper two electromagnets 50 are N poles. In state 164, in FIG. 5, the two electromagnets 50 on the left side are S poles and the two electromagnets 50 on the right side are N poles. That is, the polarity change pattern 160 is a pattern that repeats states 161 to 164. That is, the polarity change pattern 160 is an example of a pattern in which, among a plurality of electromagnets 50, a part of the polarity of an electromagnet 50 is alternately changed in a set of a plurality of adjacent electromagnets 50.

[0036] Also, for the polarity change pattern of the electromagnet 50, different patterns may be set for each of a plurality of regions obtained by dividing the plane of the shower head 13 (upper electrode) in the radial direction and the azimuthal direction. For example, in the radial direction, it may be divided into a central region, a middle region, and an edge region, and the central region may change its polarity using the polarity change pattern 150, and the middle region and the edge region may change their polarity using the polarity change pattern 160. Similarly, for the azimuthal direction, the polarity may be changed using different polarity change patterns for each of the divided regions.

[0037] In the polarity change patterns 150 and 160, the period for alternately switching the polarity of the electromagnet 50 is, for example, a time of 10% or less of the etching time. This is because the speed at which the side wall is etched is slow compared to the etching speed in the depth direction, and thus it is set as a period corresponding to the etching speed of the side wall. For example, if the etching time is 5 minutes to 20 minutes, the polarity of the electromagnet 50 is switched at a period of 10 seconds to 120 seconds.

[0038] Also, the period for alternately switching the polarities of the electromagnets 50 may be made longer in proportion to, for example, the etching time. This is because as the etching depth increases, the etching rate decreases, and by increasing the period, etching can be performed more vertically. Further, the magnitude of the set current value of each electromagnet 50 may be made larger in proportion to the etching time, that is, as the etching progresses. This is because as the etching depth increases, the angle of the incident ions in the normal direction, that is, the inclination of the axis of the precession motion, is increased, so that etching can be performed more vertically.

[0039] Also, the polarity change of each electromagnet 50 based on the polarity change patterns 150, 160 is started after a lapse of a predetermined time from the start of the plasma treatment. This is to suppress the generation of a non-uniform CD expansion region by precessing the incident angle of ions after the aperture of the mask has become a faceted shape.

[0040] FIG. 6 is a diagram showing an example of the expansion direction of a hole due to the precession motion of the incident angle of ions. A state 85 shown in FIG. 6 shows a case where etching is performed while changing the polarity of the electromagnet 50, for example, by the polarity change patterns 150, 160, after the middle stage of the etching of the film 90 to be etched. Also, the A-A cross section (Top) of the state 85 is represented as a cross section 86, and the B-B cross section (Bottom) of the state 85 is represented as a cross section 87. Here, as the film 90 to be etched, for example, a laminated film of an oxide film and a nitride film, or a laminated film of an oxide film and a silicon film can be used. That is, the hole 94 formed by etching is formed in these laminated films. Also, it is assumed that the aspect ratio of the hole 94 is 30 or more.

[0041] In state 85, the mask 91 has a faceted shape. At this time, by controlling the polarity of each electromagnet 50, the trajectory of the ions 93 incident from the aperture 92 into the hole 94 is precessed as shown by the trajectory 95. As a result, when the plane direction of the substrate W is the X and Y axes and the depth direction is the Z axis, in the cross-section 87, the cross-section of the hole 94 will spread evenly in the XY direction. Note that, as shown in FIG. 6, by precessing the trajectory of the ions 93, the size of the hole 94 in the cross-section 87 can be made larger than the size of the hole 94 in the cross-section 86 (reverse taper shape).

[0042] [Etching Method] Next, the etching method according to the present embodiment will be described. FIG. 7 is a flowchart showing an example of the etching process in the present embodiment.

[0043] In the etching method according to the present embodiment, the control unit 2 opens an opening (not shown), and the substrate W on which the film to be etched is formed is carried into the plasma processing chamber 10 and placed on the central region 111a of the substrate support unit 11. The substrate W is held by the electrostatic chuck 1111 by applying a DC voltage to the electrostatic chuck 1111. Then, the control unit 2 closes the opening and controls the exhaust system 40 to exhaust the gas from the plasma processing space 10s so that the atmosphere of the plasma processing space 10s reaches a predetermined degree of vacuum. In addition, the control unit 2 controls a temperature control module (not shown) to adjust the temperature so that the temperature of the substrate W becomes a predetermined temperature (step S1).

[0044] Next, the control unit 2 selects a polarity change pattern for each electromagnet 50 during etching (step S2). The control unit 2 may, for example, read out the polarity change pattern stored in advance together with the recipe of the etching process and select the polarity change pattern, or may accept the selection of the polarity change pattern from the operator of the plasma processing system.

[0045] Subsequently, the control unit 2 controls the gas supply unit 20 to supply the processing gas to the gas supply port 13a. The processing gas is introduced from the gas supply port 13a into the plasma processing space 10s of the plasma processing chamber 10 through the gas diffusion chamber 13b and the plurality of gas introduction ports 13c.

[0046] The control unit 2 supplies a source RF signal for plasma excitation to the substrate support unit 11 including the lower electrode by controlling the first RF generation unit 31a. Plasma is generated in the plasma processing space 10s by supplying the source RF signal for plasma excitation. Further, the control unit 2 supplies a bias RF signal to the substrate support unit 11 including the lower electrode by controlling the second RF generation unit 31b. The etched film of the substrate W is etched by the plasma generated in the plasma processing space 10s. That is, the control unit 2 controls the first RF generation unit 31a and the second RF generation unit 31b to start etching the etched film of the substrate W (step S3).

[0047] The control unit 2 determines whether or not a predetermined time has elapsed based on the etching process recipe (step S4). Here, the predetermined time is the time when the depth of the shape by etching becomes after the middle of the target depth. That is, the control unit 2 determines whether or not the etching has reached the middle stage and later. When the control unit 2 determines that the predetermined time has not elapsed (step S4: No), the etching and the determination in step S4 are continued.

[0048] When the control unit 2 determines that the predetermined time has elapsed (step S4: Yes), it controls each electromagnet 50 based on the selected polarity change pattern and starts changing the polarity of each electromagnet 50 (step S5). Note that even when the polarity change is started, the etching by plasma is continued.

[0049] The control unit 2 determines whether a predetermined shape has been obtained by the etching process (step S6). Note that the determination of whether a predetermined shape has been obtained is made, for example, based on the elapse of a predetermined processing time according to a recipe. When the control unit 2 determines that the predetermined shape has not been obtained (step S6: No), it continues the etching and the determination in step S6. On the other hand, when the control unit 2 determines that the predetermined shape has been obtained (step S6: Yes), it ends the process.

[0050] When the control unit 2 ends the process, it stops the supply of the RF signal to the lower electrode by controlling the first RF generation unit 31a and the second RF generation unit 31b. The control unit 2 opens an opening (not shown). The substrate W is carried out from the plasma processing space 10s of the plasma processing chamber 10 through the opening.

[0051] As described above, according to the present embodiment, the substrate processing apparatus (plasma processing system) includes a chamber (plasma processing chamber 10), a substrate support unit 11 configured to support the substrate W in the chamber, an upper electrode (shower head 13) facing the center of the substrate W, a plurality of electromagnets 50 arranged radially with respect to the center of the upper electrode, and a control unit 2. The control unit 2 is configured to control the substrate processing apparatus so as to select a polarity change pattern (150, 160) of the plurality of electromagnets 50 during etching. Further, the control unit 2 is configured to generate plasma from the processing gas supplied into the chamber and control the substrate processing apparatus to etch the substrate W based on the polarity change pattern. As a result, the occurrence of a non-uniform CD expansion region can be suppressed even in the middle and later stages of etching.

[0052] Further, according to the present embodiment, the polarity change pattern is a pattern in which the polarities of adjacent electromagnets 50 among the plurality of electromagnets 50 are alternately changed. As a result, the precession movement of the normal direction (incidence angle) of the ions can be achieved.

[0053] Also, according to the present embodiment, the polarity change pattern is a pattern in which, among a plurality of electromagnets 50, a part of the polarities of the electromagnets 50 is alternately changed in a set of a plurality of electromagnets 50 adjacent to one electromagnet 50. As a result, the precession movement of the normal direction (incidence angle) of the ions can be caused.

[0054] Also, according to the present embodiment, different patterns are set for each region in the upper electrode surface. As a result, for each region in the upper electrode surface, the precession movement of the normal direction (incidence angle) of the ions can be controlled.

[0055] Also, according to the present embodiment, the period of the alternating switching is a time of 10% or less of the etching time. As a result, the generation of a non-uniform CD expansion region can be suppressed even in the latter half of the etching.

[0056] Also, according to the present embodiment, the period becomes longer in proportion to the etching time. As a result, etching can be performed more vertically.

[0057] Also, according to the present embodiment, the magnitude of the set current value of the plurality of electromagnets 50 becomes larger in proportion to the etching time. As a result, as the etching becomes deeper, the inclination of the axis of the precession movement of the incident ions can be increased.

[0058] Also, according to the present embodiment, in the etching step, the polarity change of the plurality of electromagnets 50 based on the polarity change pattern is started after a lapse of a predetermined time from the start of the plasma treatment. As a result, the generation of a non-uniform CD expansion region can be suppressed even in the latter half of the etching.

[0059] Also, according to the present embodiment, the predetermined time is a time when the depth of the shape by etching becomes after the middle of the target depth. As a result, the generation of a non-uniform CD expansion region can be suppressed even in the latter half of the etching.

[0060] Moreover, according to the present embodiment, the shape formed by etching has an aspect ratio of 30 or more. As a result, in the shape of a hole or groove with a high aspect ratio, the generation of a non-uniform CD expansion region can be suppressed.

[0061] Moreover, according to the present embodiment, the shape formed by etching is formed on a laminated film of an oxide film and a nitride film, or a laminated film of an oxide film and a silicon film formed on the substrate W. As a result, in the etching of the laminated film, the generation of a non-uniform CD expansion region can be suppressed.

[0062] The embodiments disclosed this time should be considered as illustrative in all respects and not restrictive. The above embodiments may be omitted, substituted, or changed in various forms without departing from the scope and gist of the appended claims.

[0063] In the above-described embodiment, the case where the electromagnet 50 having the rod-shaped yoke 50a made of a core is used as the electromagnet 50 has been described, but it is not limited thereto. For example, an electromagnet of an air-core coil may be used.

[0064] In the above-described embodiment, the plasma processing apparatus 1 that performs processing such as etching on the substrate W using capacitively coupled plasma as the plasma source has been described as an example, but the disclosed technology is not limited thereto. As long as it is an apparatus that performs processing on the substrate W using plasma, the plasma source is not limited to capacitively coupled plasma, and for example, any plasma source such as inductively coupled plasma, microwave plasma, magnetron plasma, etc. can be used. For example, when inductively coupled plasma is used, by arranging the electromagnet 50 on the back side of the electrostatic chuck 1111 in the substrate support portion 11, an in-plane distribution of the electron density (Ne) can be formed in the same manner as in the above-described embodiment. Further, for example, when inductively coupled plasma is used, an in-plane distribution of the electron density may be formed by combining and controlling a plurality of induction coils.

[0065] Note that the present disclosure can also adopt the following configuration. (1) A substrate processing method in a substrate processing apparatus, The substrate processing apparatus includes: a chamber; a substrate support configured to support a substrate in the chamber; an upper electrode facing the center of the substrate; a plurality of electromagnets arranged radially with respect to the center of the upper electrode; and includes: a step of selecting a polarity change pattern of the plurality of electromagnets during etching; a step of generating plasma from a processing gas supplied into the chamber and etching the substrate based on the polarity change pattern; and has: a substrate processing method. (2) The polarity change pattern is a pattern in which the polarities of adjacent electromagnets among the plurality of electromagnets are alternately changed. The substrate processing method according to (1) above. (3) The polarity change pattern is a pattern in which, among the plurality of electromagnets, in a set of a plurality of electromagnets adjacent to one electromagnet, a part of the polarity of the electromagnet is alternately changed. The substrate processing method according to (1) above. (4) For each region in the upper electrode surface, a different pattern is set as the polarity change pattern. The substrate processing method according to any one of (1) to (3) above. (5) The period of the alternating switching is a time of 10% or less of the etching time. The substrate processing method according to (2) or (3) above. (6) The period becomes longer in proportion to the etching time. The substrate processing method according to (5) above. (7) The magnitude of the set current value of the plurality of electromagnets becomes larger in proportion to the etching time. The substrate processing method according to (5) or (6) above. (8) The step of etching starts the polarity change of the plurality of electromagnets based on the polarity change pattern after a lapse of a predetermined time from the start of the plasma treatment. The substrate processing method according to any one of (1) to (7) above. (9) The predetermined time is a time when the depth of the shape by etching becomes after the middle of the target depth. The substrate processing method according to (8) above. (10) The shape by etching has an aspect ratio of 30 or more. The substrate processing method according to (9) above. (11) The shape by etching is formed on a laminated film of an oxide film and a nitride film formed on the substrate, or a laminated film of the oxide film and a silicon film. The substrate processing method according to (10) above. (12) A substrate processing apparatus, comprising: a chamber; a substrate support portion configured to support a substrate in the chamber; an upper electrode facing the center of the substrate; a plurality of electromagnets arranged radially with respect to the center of the upper electrode; a control unit; and the control unit is configured to control the substrate processing apparatus to select a polarity change pattern of the plurality of electromagnets during etching; the control unit is configured to generate plasma from a processing gas supplied into the chamber and control the substrate processing apparatus to etch the substrate based on the polarity change pattern. Substrate processing apparatus.

Explanation of symbols

[0066] 1 Plasma processing apparatus 2 Control unit 10 Plasma processing chamber 11 Substrate support portion 13 Shower head 50 Electromagnet 51 Central part facing group 52 Peripheral part facing group 53 Outer facing group 80, 81 Sets 150, 160 Polarity change patterns W Substrate

Claims

1. A substrate processing method in a substrate processing apparatus, wherein the substrate processing apparatus comprises a chamber, a substrate support configured to support a substrate within the chamber, an upper electrode facing the center of the substrate, and a plurality of electromagnets radially arranged with respect to the center of the upper electrode, and includes: a step of selecting a polarity change pattern of the plurality of electromagnets during etching; a step of generating plasma from a processing gas supplied into the chamber and etching the substrate based on the polarity change pattern, and has: wherein the polarity change pattern is a pattern in which the polarities of adjacent electromagnets among the plurality of electromagnets are alternately changed, a substrate processing method.

2. A substrate processing method in a substrate processing apparatus, wherein the substrate processing apparatus comprises a chamber, a substrate support configured to support a substrate within the chamber, an upper electrode facing the center of the substrate, and a plurality of electromagnets radially arranged with respect to the center of the upper electrode, and includes: a step of selecting a polarity change pattern of the plurality of electromagnets during etching; a step of generating plasma from a processing gas supplied into the chamber and etching the substrate based on the polarity change pattern, and has: wherein the polarity change pattern is a pattern in which, among the plurality of electromagnets, a part of the polarities of one electromagnet are alternately changed in a set of a plurality of adjacent electromagnets, a substrate processing method.

3. A substrate processing method in a substrate processing apparatus, wherein the substrate processing apparatus comprises a chamber, a substrate support configured to support a substrate within the chamber, an upper electrode facing the center of the substrate, and a plurality of electromagnets radially arranged with respect to the center of the upper electrode, and includes: a step of selecting a polarity change pattern of the plurality of electromagnets during etching; a step of generating plasma from a processing gas supplied into the chamber and etching the substrate based on the polarity change pattern, and has: wherein different patterns are set for each region in the upper electrode plane, a substrate processing method.

4. The period of the alternating switching is a time of 10% or less of the etching time, The substrate processing method according to claim 1 or 2.

5. The period becomes longer in proportion to the etching time, The substrate processing method according to claim 4.

6. The magnitude of the set current value of the plurality of electromagnets increases in proportion to the etching time. The substrate processing method according to claim 4.

7. In the step of etching, the polarity change of the plurality of electromagnets based on the polarity change pattern is started after a lapse of a predetermined time from the start of the plasma treatment. The substrate processing method according to any one of claims 1 to 3.

8. The predetermined time is a time when the depth of the shape by etching becomes after the middle of the target depth. The substrate processing method according to claim 7.

9. The shape by etching has an aspect ratio of 30 or more. The substrate processing method according to claim 8.

10. The shape by etching is formed in a laminated film of an oxide film and a nitride film formed on the substrate, or a laminated film of the oxide film and a silicon film. The substrate processing method according to claim 9.

11. A substrate processing apparatus, comprising: a chamber; a substrate support portion configured to support a substrate in the chamber; an upper electrode facing the center of the substrate; a plurality of electromagnets radially arranged with respect to the center of the upper electrode; a control unit and is provided with The control unit is configured to control the substrate processing apparatus so as to select a polarity change pattern of the plurality of electromagnets during etching. The control unit is configured to generate plasma from a processing gas supplied into the chamber and control the substrate processing apparatus so as to etch the substrate based on the polarity change pattern. The polarity change pattern is a pattern in which the polarities of adjacent electromagnets among the plurality of electromagnets are alternately changed. Substrate processing apparatus.

12. A substrate processing apparatus, comprising: a chamber; a substrate support portion configured to support a substrate in the chamber; an upper electrode facing the center of the substrate; a plurality of electromagnets radially arranged with respect to the center of the upper electrode; a control unit and is provided with The control unit is configured to control the substrate processing apparatus so as to select a polarity change pattern of the plurality of electromagnets during etching. The control unit is configured to generate plasma from a processing gas supplied into the chamber and control the substrate processing apparatus so as to etch the substrate based on the polarity change pattern. The polarity change pattern is a pattern in which, among the plurality of electromagnets, in a set of a plurality of electromagnets adjacent to one electromagnet, a part of the polarity of the electromagnet is alternately changed. Substrate processing apparatus. **Claim 13**: A substrate processing apparatus, comprising: a chamber; a substrate support configured to support a substrate in the chamber; an upper electrode facing the center of the substrate; a plurality of electromagnets radially arranged with respect to the center of the upper electrode; a control unit; The control unit is configured to control the substrate processing apparatus to select a polarity change pattern of the plurality of electromagnets during etching. The control unit is configured to generate plasma from a processing gas supplied into the chamber and control the substrate processing apparatus to etch the substrate based on the polarity change pattern. The polarity change pattern is set to be different for each region in the upper electrode plane. Substrate processing apparatus. ​

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