Method for cleaning plasma processing apparatus, and plasma processing apparatus

Abstract

A method for cleaning a plasma processing apparatus includes: (a) introducing a cleaning gas into a chamber of the plasma processing apparatus; a step (b) of generating plasma in the chamber under a first condition to perform a first cleaning; and (c) a step of generating plasma in the chamber under a second condition to perform second cleaning, in the cleaning method of the plasma processing apparatus, adjusting at least one of the first condition and the second condition, in the step (b), a first ratio of the thickness of the inner sheath layer to the thickness of the outer sheath layer is different from a second ratio of the thickness of the inner sheath layer to the thickness of the outer sheath layer in the sheath layer of the plasma generated in the step (c).

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a cleaning method of a plasma processing apparatus and a plasma processing apparatus. BACKGROUND

[0002] A plasma processing apparatus provided with an upper electrode is disclosed in Patent Literature 1. The upper electrode has a first upper electrode and a second upper electrode that is disposed around the first upper electrode in a manner of surrounding the first upper electrode and is insulated from the first upper electrode.

[0003] PRIOR ART DOCUMENTS

[0004] PATENT LITERATURE

[0005] Patent Literature 1: Japanese Patent Application Publication No. 2017-112275 SUMMARY

[0006] PROBLEMS TO BE SOLVED BY THE INVENTION

[0007] The technology according to the present disclosure is used to efficiently perform cleaning of a plasma processing apparatus.

[0008] SOLUTION TO PROBLEM

[0009] One embodiment of the present disclosure is a cleaning method of a plasma processing apparatus, including: a process (a) of introducing a cleaning gas into a chamber of the plasma processing apparatus; a process (b) of generating plasma in the chamber under first conditions to perform first cleaning; and a process (c) of generating plasma in the chamber under second conditions to perform second cleaning, in the cleaning method of the plasma processing apparatus, at least either of the first conditions and the second conditions is adjusted so that a first ratio of a thickness of an inner sheath layer to a thickness of an outer sheath layer in a sheath layer of the plasma generated in the process (b) is different from a second ratio of the thickness of the inner sheath layer to the thickness of the outer sheath layer in the sheath layer of the plasma generated in the process (c).

[0010] EFFECT OF THE INVENTION

[0011] According to the present disclosure, it is possible to efficiently perform cleaning of a plasma processing apparatus. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 is an explanatory diagram schematically showing the structure of a plasma processing system.

[0013] Figure 2 is an explanatory diagram showing a case where a gap between an inner upper electrode and an outer upper electrode is cleaned.

[0014] Figure 3is an explanatory diagram showing a state of cleaning the gap between the inner upper electrode and the outer upper electrode.

[0015] Figure 4 is an explanatory diagram showing a state of cleaning the gap between the inner upper electrode and the outer upper electrode.

[0016] Figure 5 is an explanatory diagram showing an example of a cleaning method of the gap between the inner upper electrode and the outer upper electrode.

[0017] Figure 6 is an explanatory diagram showing a behavior of removing the attached matter from the gap.

[0018] Figure 7 is an explanatory diagram showing an example of a cleaning method of the gap between the inner upper electrode and the outer upper electrode in another embodiment.

[0019] Figure 8 is an explanatory diagram showing a state of cleaning the gap between the inner upper electrode and the outer upper electrode in another embodiment.

[0020] Figure 9 is an explanatory diagram showing a state of cleaning the gap between the inner upper electrode and the outer upper electrode in another embodiment.

[0021] Figure 10 is an explanatory diagram showing a state of cleaning the gap between the inner upper electrode and the outer upper electrode in another embodiment.

[0022] Figure 11 is an explanatory diagram showing a state of cleaning the gap between the electrostatic chuck and the edge ring.

[0023] Figure 12 is an explanatory diagram showing a state of cleaning the gap between the electrostatic chuck and the edge ring. DETAILED DESCRIPTION

[0024] In a manufacturing process of a semiconductor device, various plasma processes such as etching process, film forming process, diffusion process, and the like are performed on a semiconductor substrate (hereinafter referred to as "substrate"). In the plasma process, plasma is generated by exciting a processing gas, and the substrate is processed by the plasma.

[0025] The plasma processing is performed using, for example, a plasma processing apparatus of a capacitively coupled type (CCP: Capacitively Coupled Plasma). The plasma processing apparatus has a chamber, a substrate support portion, a plasma generating portion, and the like. In addition, the plasma processing apparatus has an upper electrode that constitutes at least a portion of a top portion of the chamber and a lower electrode that is provided to the substrate support portion. For example, as disclosed in Patent Document 1, the upper electrode has a first upper electrode (inner side upper electrode) and a second upper electrode (outer side upper electrode). The outer side upper electrode is provided in a manner of surrounding a periphery of the inner side upper electrode, and the inner side upper electrode is insulated from the outer side upper electrode.

[0026] In the plasma processing, a reaction product is generated. The reaction product is deposited as a deposit attached to a side wall of the chamber, a member in the chamber, and the like. In particular, for example, when the deposit is deposited in a minute gap formed between the inner side upper electrode and the outer side upper electrode, the gap is narrowed, and thus can become a main cause of abnormal discharge. Therefore, in order to remove the deposit, dry cleaning using plasma is performed in the chamber. That is, in the dry cleaning, a cleaning gas is excited to generate plasma, and the deposit is removed using the plasma. Specifically, the dry cleaning removes the deposit by a chemical reaction based on radicals and a physical reaction based on ions (sputtering).

[0027] However, in the conventional dry cleaning, for example, a DC (direct current) voltage applied to the inner side upper electrode and the outer side upper electrode is constant, and ions are incident to the minute gap between the inner side upper electrode and the outer side upper electrode in one direction, and thus it is difficult to remove the deposit attached to the gap. In addition, the deposit is, for example, a compound containing yttrium (Y), and such a deposit is difficult to be removed chemically. Thus, the conventional cleaning method has room for improvement.

[0028] The technology related to the present disclosure is used to efficiently perform cleaning of a plasma processing apparatus. Hereinafter, a plasma processing apparatus and a dry cleaning method of a plasma processing apparatus related to the present embodiment will be described with reference to the drawings. Furthermore, in the present specification and the drawings, for elements having substantially the same functional structure, repeated description is omitted by labeling the same reference numerals.

[0029] <Plasma processing system and plasma processing apparatus>

[0030] Hereinafter, a structure example of a plasma processing system will be described. Figure 1 is a view for explaining a structure example of a plasma processing apparatus of a capacitively coupled type.

[0031] A plasma processing system includes a capacitively coupled plasma processing apparatus 1 and a control section 2. The capacitively coupled plasma processing apparatus 1 includes a plasma processing chamber 10, a gas supply section 20, a power supply 30, and an exhaust system 40. In addition, the plasma processing apparatus 1 includes a substrate support section 11 and a gas introduction section. The gas introduction section is configured to introduce at least one processing gas or at least one cleaning gas into the plasma processing chamber 10. The gas introduction section includes a showerhead assembly 13. The substrate support section 11 is disposed within the plasma processing chamber 10. The showerhead assembly 13 is disposed above the substrate support section 11. In one embodiment, the showerhead assembly 13 constitutes at least a portion of a ceiling of the plasma processing chamber 10. In addition, the showerhead assembly 13 is supported to a sidewall 10a of the plasma processing chamber 10 via an insulating member (omitted from illustration). The plasma processing chamber 10 has a plasma processing space 10s defined by the showerhead assembly 13, the sidewall 10a of the plasma processing chamber 10, and the substrate support section 11. The plasma processing chamber 10 has at least one gas supply port for supplying at least one processing gas or at least one cleaning gas to the plasma processing space 10s and at least one gas exhaust port for exhausting gas from the plasma processing space. The plasma processing chamber 10 is grounded. The showerhead assembly 13 and the substrate support section 11 are electrically insulated from a housing of the plasma processing chamber 10.

[0032] The substrate support section 11 includes a main body section 111 and a ring assembly 112. The main body section 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 the substrate W. The annular region 111b of the main body section 111 encloses the central region 111a of the main body section 111 when viewed from above. The substrate W is disposed on the central region 111a of the main body section 111, and the ring assembly 112 is disposed on the annular region 111b of the main body section 111 so as to enclose the substrate W on the central region 111a of the main body section 111. Thus, 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.

[0033] In one embodiment, the main body 111 includes a base 1110 and an electrostatic chuck 1111. The base 1110 includes an electrically conductive member. The electrically 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 in the ceramic member 1111a. The ceramic member 1111a has a central region 111a. In one embodiment, the ceramic member 1111a also has a ring-shaped region 111b. Further, other members surrounding the electrostatic chuck 1111, such as a ring-shaped insulating member, can also have the ring-shaped region 111b. In this case, the ring assembly 112 can be disposed on either the ring-shaped electrostatic chuck or the ring-shaped insulating member, or on both the electrostatic chuck 1111 and the ring-shaped insulating member. In addition, at least one RF / DC electrode coupled to the RF (Radio Frequency) power source 31 and / or the DC (Direct Current) power source 32 described later can be disposed in the ceramic member 1111a. In this case, the at least one RF / DC electrode functions as a lower electrode. The RF / DC electrode is also referred to as a bias electrode in a case where a bias RF signal and / or a DC signal described later is supplied to the RF / DC electrode. Further, the electrically conductive member of the base 1110 and the at least one RF / DC electrode can function as a plurality of lower electrodes. In addition, the electrostatic electrode 1111b can also function as a lower electrode. Thus, the substrate support portion 11 includes at least one lower electrode.

[0034] The ring assembly 112 includes one or more ring-shaped members. In one embodiment, the one or more ring-shaped members include one or more edge rings 113 and at least one cover ring 114. The edge ring 113 is disposed in a ring shape so as to surround the substrate W on the main body 111. The cover ring 114 is disposed in a ring shape so as to surround the edge ring 113. The edge ring 113 is formed of an electrically conductive material or an insulating material, such as Si or SiC in the case of an electrically conductive material. The cover ring 114 is formed of an insulating material.

[0035] In addition, the substrate support portion 11 can include a temperature adjustment module configured to adjust at least one of the electrostatic chuck 1111, the ring assembly 112, and the substrate W to a target temperature. The temperature adjustment module can include a heater, a heat transfer medium, the flow path 1110a, or a combination thereof. A heat transfer fluid such as a salt water or a gas is caused to flow in 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. In addition, the substrate support portion 11 can 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.

[0036] The showerhead assembly 13 is configured to introduce at least one process gas or at least one cleaning gas from the gas supply portion 20 into the plasma processing space 10s. The showerhead assembly 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 or the cleaning gas supplied to the gas supply port 13a is introduced into the plasma processing space 10s from the plurality of gas introduction ports 13c through the gas diffusion chamber 13b. In addition, the gas introduction portion can include, in addition to the showerhead assembly 13, one or more side gas injectors (SGIs) installed to one or more opening portions formed in the side wall 10a.

[0037] The showerhead assembly 13 includes at least one upper electrode. In one embodiment, the showerhead assembly 13 includes an inner upper electrode 130, an outer upper electrode 131, and an electrode support 132. The inner upper electrode 130 is disposed above the central region 111a of the main body portion 111. The inner upper electrode 130 is an electrode plate having a substantially circular plate shape. The outer upper electrode 131 is disposed above the annular region 111b (ring assembly 112) of the main body portion 111 in a manner of surrounding the inner upper electrode 130. The outer upper electrode 131 is an electrode plate having a substantially annular shape. The inner upper electrode 130 and the outer upper electrode 131 are each formed of an electrically conductive material, for example, Si or SiC. The electrode support 132 supports the inner upper electrode 130 and the outer upper electrode 131 in a detachable manner. The electrode support 132 is formed of an electrically conductive material, for example, aluminum.

[0038] The gas supply section 20 can also include at least one gas source 21 and at least one flow controller 22. In one embodiment, the gas supply section 20 is configured to supply at least one process gas or at least one cleaning gas from the corresponding gas source 21 to the showerhead assembly 13 via the corresponding flow controller 22. Each flow controller 22 can also include, for example, a mass flow controller or a pressure-controlled flow controller. Also, the gas supply section 20 can include one or more flow modulation devices that modulate or pulse the flow of at least one process gas or at least one cleaning gas.

[0039] The power supply 30 includes an RF power source 31 coupled to the plasma processing chamber 10 via at least one impedance matching circuit. The RF power source 31 is configured to supply at least one RF signal (RF power) to the at least one lower electrode and / or the at least one upper electrode 130, 131. Thereby, a plasma is formed from the at least one process gas or the at least one cleaning gas supplied to the plasma processing space 10s. Thus, the RF power source 31 can function as at least a part of a plasma generation section configured to generate a plasma from one or more process gases or one or more cleaning gases in the plasma processing chamber 10. Further, by supplying a bias RF signal to the at least one lower electrode, a bias potential can be generated at the substrate W and ion components in the formed plasma can be attracted to the substrate W.

[0040] In one embodiment, the RF power source 31 includes a first RF generation section 31a and a second RF generation section 31b. The first RF generation section 31a is configured to be coupled to the at least one lower electrode and / or the at least one upper electrode 130, 131 via at least one impedance matching circuit, and 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 section 31a can also be configured to generate a plurality of source RF signals having different frequencies. The generated source RF signal(s) is / are supplied to the at least one lower electrode and / or the at least one upper electrode 130, 131.

[0041] The second RF generating section 31b is configured to be coupled to the at least one lower electrode via at least one impedance matching circuit, and to generate a bias RF signal (bias RF power). The bias RF signal can have the same frequency as the source RF signal, or can have a different frequency. In one embodiment, the bias RF signal has a frequency lower than the frequency of the source RF signal. In one embodiment, the bias RF signal has a frequency in the range of 100 kHz to 60 MHz. In one embodiment, the second RF generating section 31b can also be configured to generate a plurality of bias RF signals having different frequencies. The generated bias RF signal(s) is / are supplied to the at least one lower electrode. In addition, in various embodiments, at least one of the source RF signal and the bias RF signal can be pulsed.

[0042] In addition, the power supply 30 can also include a DC power supply 32 coupled to the plasma processing chamber 10. The DC power supply 32 includes a first DC generating section 32a, a second DC generating section 32b, a third DC generating section 32c, and a fourth DC generating section 32d. In one embodiment, the first DC generating section 32a is configured to be connected to the inner upper electrode 130, and to generate a first DC signal. The generated first bias DC signal is applied to the inner upper electrode 130. In one embodiment, the second DC generating section 32b is configured to be connected to the outer upper electrode 131, and to generate a second DC signal. The generated second bias DC signal is applied to the outer upper electrode 131. In one embodiment, the third DC generating section 32c is configured to be connected to the at least one lower electrode, and to generate a third DC signal. The generated third bias DC signal is applied to the at least one lower electrode. In one embodiment, the fourth DC generating section 32d is configured to be connected to the one or more edge rings 113, and to generate a fourth DC signal. The generated fourth DC signal is applied to the one or more edge rings 113.

[0043] In various embodiments, at least one of the first to third DC signals can also be pulsed. In this case, a sequence of voltage pulses is applied to the at least one upper electrode 130, 131 and / or the at least one lower electrode. The voltage pulses can also have a rectangular, trapezoidal, triangular or a combination of these shapes. In one embodiment, a waveform generation section for generating a sequence of voltage pulses from a DC signal is connected between the first DC generation section 32a and the inner upper electrode 130. Thus, the first DC generation section 32a and the waveform generation section constitute a voltage pulse generation section. In the case where the second DC generation section 32b and the waveform generation section constitute a voltage pulse generation section, the voltage pulse generation section is connected to the outer upper electrode 131. In the case where the third DC generation section 32c and the waveform generation section constitute a voltage pulse generation section, the voltage pulse generation section is connected to the at least one lower electrode. The voltage pulses can have either a positive polarity or a negative polarity. In addition, the sequence of voltage pulses can include one or more positive polarity voltage pulses and one or more negative polarity voltage pulses in one cycle. Furthermore, the first to third DC generation sections 32a to 32c can be provided in addition to the RF power source 31 or the third DC generation section 32c can be provided instead of the second RF generation section 31b.

[0044] The exhaust system 40 can be connected to a gas exhaust port 10e provided at the bottom of the plasma processing chamber 10, for example. The exhaust system 40 can also include a pressure adjustment valve and a vacuum pump. The pressure adjustment valve adjusts the pressure in the plasma processing space 10s. The vacuum pump can include a turbo molecular pump, a dry pump, or a combination thereof.

[0045] The control section 2 processes computer executable commands for causing the plasma processing apparatus 1 to perform various processes described in the present disclosure. The control section 2 can control each element of the plasma processing apparatus 1 to perform various processes described herein. In one embodiment, part or all of the control section 2 can also be included in the plasma processing apparatus 1. The control section 2 can include a processing section 2a1, a storage section 2a2, and a communication interface 2a3. The control section 2 is implemented by, for example, a computer 2a. The processing section 2a1 can be configured to perform various control actions by reading out a program from the storage section 2a2 and executing the read-out program. The program can be pre-stored in the storage section 2a2 or acquired via a medium as needed. The acquired program is stored in the storage section 2a2, read out from the storage section 2a2 by the processing section 2a1, and executed. The medium can be various storage media readable by the computer 2a or a communication line connected to the communication interface 2a3. The processing section 2a1 can be a CPU (Central Processing Unit). The storage section 2a2 can 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 can communicate with the plasma processing apparatus 1 via a communication line such as a LAN (Local Area Network).

[0046] <Plasma processing method>

[0047] Next, plasma processing using the plasma processing apparatus 1 configured as described above is described.

[0048] First, the substrate W is carried into the inside of the plasma processing chamber 10, and placed on the electrostatic chuck 1111 of the substrate support section 11. Next, a voltage is applied to the electrostatic electrode 1111b of the electrostatic chuck 1111, and thus the substrate W is adsorbed and held to the electrostatic chuck 1111 by electrostatic force.

[0049] When the substrate W is adsorbed and held to the electrostatic chucking plate 1111, then, the inside of the plasma processing chamber 10 is reduced in pressure to a prescribed vacuum degree. Then, a processing gas is supplied from the gas supply portion 20 to the plasma processing space 10s via the shower head assembly 13. In addition, source RF power for plasma generation is supplied from the first RF generation portion 31a to the lower electrode, whereby the processing gas is excited to generate plasma. At this time, bias RF power can also be supplied from the second RF generation portion 31b. Then, in the plasma processing space 10s, the substrate W is subjected to plasma processing by the action of the generated plasma.

[0050] [Cleaning method]

[0051] In the plasma processing, reaction products are generated. The reaction products adhere to the side wall 10a of the plasma processing chamber 10, members inside the plasma processing chamber 10, and the like, and are deposited as deposits. Therefore, in order to remove the deposits, dry cleaning using plasma is performed inside the plasma processing chamber 10. That is, in the dry cleaning, a cleaning gas is excited to generate plasma, and the deposits are removed using the plasma. Further, the kind of the cleaning gas is appropriately selected depending on the kind of the deposits. For example, in the case where the deposits are yttrium compounds, O2 gas is used as the cleaning gas.

[0052] The dry cleaning includes a case where it is performed in a state where the substrate W is supported by the substrate support portion 11, and a case where it is performed in a state where the substrate W is not supported by the substrate support portion 11 (substrate-free dry cleaning). In either dry cleaning, the inside of the plasma processing chamber 10 is first reduced in pressure to a prescribed vacuum degree, as in the plasma processing. Then, a cleaning gas is supplied from the gas supply portion 20 to the plasma processing space 10s via the shower head assembly 13. In addition, source RF power for plasma generation is supplied from the first RF generation portion 31a to the lower electrode, whereby the cleaning gas is excited to generate plasma. At this time, bias RF power can also be supplied from the second RF generation portion 31b. Then, in the plasma processing space 10s, the inside of the plasma processing chamber 10 is cleaned by the action of the generated plasma.

[0053] [Cleaning of upper electrode]

[0054] When the reaction product adheres to the minute gap G formed between the inner upper electrode 130 and the outer upper electrode 131 and the adherent is deposited, the gap G becomes narrow, and thus can become a main cause of abnormal discharge. However, in the conventional dry cleaning, the DC voltage applied to the upper electrode is constant, and ions are incident to the gap G in one direction, and thus it is difficult to remove the adherent adhered to the gap G. Therefore, in the present embodiment, the thickness of the sheath layer of the plasma below the inner upper electrode 130 and the thickness of the sheath layer of the plasma below the outer upper electrode 131 are controlled respectively, the incident direction of ions to the gap G is controlled, and thus the adherent adhered to the gap G is removed.

[0055] Here, the thickness of the sheath layer of the plasma can be calculated, for example, by the following formula (1).

[0056] [Numeral 1]

[0057]

[0058] where V dc is the self-bias (self-bias potential), Te is the plasma temperature, Ne is the plasma density, ε0 is the dielectric constant of vacuum, and e is the elementary charge.

[0059] According to the above formula (1), when the self-bias is large, the thickness of the sheath layer becomes large, and when the self-bias is small, the thickness of the sheath layer becomes small. Therefore, in the present embodiment, the DC voltage applied from the first DC generation section 32a to the inner upper electrode 130 (hereinafter, referred to as "inner DC voltage") is controlled to control the self-bias of the inner upper electrode 130. In addition, the DC voltage applied from the second DC generation section 32b to the outer upper electrode 131 (hereinafter, referred to as "outer DC voltage") is controlled to control the self-bias of the outer upper electrode 131.

[0060] Figures 2-4 is an explanatory view showing a case where the gap G between the inner upper electrode 130 and the outer upper electrode 131 is cleaned. In the following description, the sheath layer of the plasma generated below the inner upper electrode 130 is referred to as the inner sheath layer Sa, and the sheath layer of the plasma generated below the outer upper electrode 131 is referred to as the outer sheath layer Sb. In addition, the thickness da of the inner sheath layer Sa is the distance from the plasma to the lower surface of the inner upper electrode 130, and the thickness db of the outer sheath layer Sb is the distance from the plasma to the lower surface of the outer upper electrode 131.

[0061] Figure 2is a diagram of a case where the inner DC voltage is greater than the outer DC voltage. In the following description, this cleaning condition is referred to as a first condition. In this case, the thickness da of the inner sheath layer Sa is greater than the thickness db of the outer sheath layer Sb. Then, the incident direction of the ions with respect to the gap G (arrow in the drawing) is inclined from the vertical direction toward the inner upper electrode 130 side, and the ions are incident to the side surface Ga of the gap G on the inner upper electrode 130 side. Also, this side surface Ga becomes a cleaning target region (hatched region in the drawing), and the deposits D attached to this side surface Ga are removed by the ions. The removed deposits D are exhausted from the gas exhaust port 10e provided at the bottom of the plasma processing chamber 10.

[0062] In addition, by controlling the ratio da / db (hereinafter referred to as "thickness ratio") of the thickness da of the inner sheath layer Sa to the thickness db of the outer sheath layer Sb, it is possible to adjust the inclination angle of the incident direction of the ions with respect to the vertical direction. That is, if the thickness ratio da / db is large, the inclination angle of the ions becomes large. In addition, instead of the thickness ratio da / db, the difference between the thickness da of the inner sheath layer Sa and the thickness db of the outer sheath layer Sb can also be controlled.

[0063] Figure 3 is a diagram of a case where the inner DC voltage is the same as the outer DC voltage. In the following description, this cleaning condition is referred to as a second condition. In this case, the thickness da of the inner sheath layer Sa is the same as the thickness db of the outer sheath layer Sb. Then, the incident direction of the ions with respect to the gap G (arrow in the drawing) becomes the vertical direction, and the ions are incident to the upper surface Gb of the gap G. Also, this upper surface Gb becomes a cleaning target region (hatched region in the drawing), and the deposits D attached to this upper surface Gb are removed by the ions and exhausted from the gas exhaust port 10e.

[0064] Figure 4 is a diagram of a case where the inner DC voltage is less than the outer DC voltage. In the following description, this cleaning condition is referred to as a third condition. In this case, the thickness da of the inner sheath layer Sa is less than the thickness db of the outer sheath layer Sb. Then, the incident direction of the ions with respect to the gap G (arrow in the drawing) is inclined from the vertical direction toward the outer upper electrode 131 side, and the ions are incident to the side surface Gc of the gap G on the outer upper electrode 131 side. Also, this side surface Gc becomes a cleaning target region (hatched region in the drawing), and the deposits D attached to this side surface Gc are removed by the ions and exhausted from the gas exhaust port 10e. In addition, in this case, if the thickness ratio da / db of the sheath layers is small, the inclination angle of the ions becomes large.

[0065] In the present embodiment, after the cleaning gas is introduced into the plasma processing space 10s, the first cleaning (S1) under the first condition, the second cleaning (S2) under the second condition, and the third cleaning (S3) under the third condition are sequentially performed. Figure 2 In the present embodiment, after the cleaning gas is introduced into the plasma processing space 10s, the first cleaning (S1) under the first condition, the second cleaning (S2) under the second condition, and the third cleaning (S3) under the third condition are sequentially performed.Figure 3 Third cleaning under the third condition Figure 4 Furthermore, these first to third conditions are conditions that change the inner DC voltage and the outer DC voltage as described above, but other conditions, such as the source RF power supplied to the lower electrode and the bias RF power, are the same. In this case, the side surface Ga, the upper surface Gb, and the side surface Gc in the gap G can be cleaned sequentially, and the gap G can be cleaned over a wide range and efficiently. In addition, as a result, abnormal discharge between the inner upper electrode 130 and the outer upper electrode 131 can be suppressed.

[0066] Figure 5 This is an illustrative diagram showing an example of a cleaning method for gap G. In Figure 5 In this context, the values ​​of the inner and outer DC voltages are examples, but not limited to them. The cleaning area refers to the area to be cleaned where the deposit D is removed. The arrows representing incident ions indicate the incident direction of the ions against the gap G and the ion's removal force on the deposit D (hereinafter referred to as "sputtering force"). The incident direction of the ions is indicated by the direction of the arrow, and... Figures 2-4 Similarly, the left side relative to the vertical direction is the inner upper electrode 130 side, and the right side is the outer upper electrode 131 side. The thickness of the arrow indicates the sputtering force of the ions.

[0067] Steps S1~S2 are the first cleaning under the first condition ( Figure 2 The inner DC voltage is greater than the outer DC voltage, and the incident direction of the ions tilts from the vertical direction towards the inner upper electrode 130, thus cleaning the side Ga. In steps S1-S2, the inner DC voltage is fixed at 500V, and the outer DC voltage is increased to 150V and 300V. That is, the outer DC voltage is changed (scanned) in stages before entering step S3 described later. As a result, the sheath thickness ratio da / db also decreases in stages, and the tilt angle of the ions decreases in stages. In addition, as the outer DC voltage increases, the sputtering force of the ions increases.

[0068] Step S3 is the second cleaning under the second condition ( Figure 3 The inner DC voltage and the outer DC voltage are both 500V, the incident direction of the ions is vertical, and the upper surface Gb is cleaned.

[0069] Steps S4 to S8 are the third cleaning under the third condition. Figure 4The inner DC voltage is lower than the outer DC voltage, causing the ion incident direction to tilt from the vertical direction towards the upper outer electrode 131, thus cleaning the side surface Gc. In steps S4-S8, the inner DC voltage is fixed at 300V, while the outer DC voltage is increased in stages from 500V to 1400V. Consequently, the sheath thickness ratio da / db also decreases in stages, and the ion tilt angle increases in stages. Furthermore, as the outer DC voltage increases, the ion sputtering force increases.

[0070] According to this embodiment, by controlling the inner DC voltage and the outer DC voltage, and more specifically, by controlling the balance (ratio) of the inner DC voltage and the outer DC voltage, the thickness ratio da / db of the sheath can be controlled to arbitrarily control the incident direction of ions against the gap G. Furthermore, by sequentially performing the first to third cleaning processes, the side surface Ga, the upper surface Gb, and the side surface Gc in the gap G are cleaned in sequence, efficiently removing the deposits D on these surfaces.

[0071] Furthermore, by controlling the magnitudes of the inner and outer DC voltages, the sputtering force of the ions can be controlled. Therefore, it is possible to more efficiently remove the deposits D on the side Ga, the top Gb, and the side Gc.

[0072] Furthermore, in the first cleaning (steps S1-S2), the outer DC voltage is changed in stages, thus changing the tilt angle of the ions in stages. This allows the ions to collide with the entire surface of the side Ga, thereby cleaning the side Ga over a large area. Similarly, in the third cleaning (steps S4-S8), the outer DC voltage is also changed in stages, thus changing the tilt angle of the ions in stages. This allows the ions to collide with the entire surface of the side Gc, thereby cleaning the side Gc over a large area.

[0073] Here, for example, in such Figure 6 When cleaning the side surface Ga of the gap G as shown, the deposits D removed from the side surface Ga sometimes re-adhere to the upper surface Gb and the side surface Gc instead of being discharged from the gap G. Therefore, it is preferable to repeat the first cleaning under the first condition. Figure 2 Second cleaning under the second condition () Figure 3 Third cleaning under the third condition Figure 4 ).

[0074] Figure 7 This is an explanatory diagram illustrating an example of a cleaning method for gap G as described in other embodiments. In this embodiment, following Figure 5 Steps S1 to S8 of the above-described embodiment are followed by steps S9 to S14.

[0075] Steps S9 to S12 are cleaning under the third condition following step S8. Figure 4 This is used to clean the side Gc. In steps S9-S12, the inner DC voltage is continuously fixed at 300V starting from step S8, while the outer DC voltage is gradually decreased starting from step S8, specifically, gradually decreased to 1200V~500V. That is, in the third cleaning, the outer DC voltage is gradually increased in steps S4-S8 and then gradually decreased in steps S8-S12. As a result, in steps S9-S12, the sheath thickness ratio da / db also gradually increases, and the ion tilt angle gradually decreases. In addition, as the outer DC voltage decreases, the ion sputtering force decreases.

[0076] Step S13 is the second cleaning under the second condition ( Figure 3 This is used to clean the upper surface Gb. In step S13, the inner DC voltage is set to be greater than 500V in step S12, and the outer DC voltage is continuously set to 500V starting from step S12. That is, in step S13, the inner DC voltage and the outer DC voltage are both 500V.

[0077] Step S14 is the first cleaning under the first condition ( Figure 2 ), used to clean the side Ga. In step S14, the inner DC voltage is continuously set to 500V starting from step S13, and the outer DC voltage is reduced starting from step S13, specifically, set to 300V.

[0078] In addition, Figure 7 The cleaning cycle for gap G is shown. That is, in this embodiment, after performing steps S1 to S14 as described above, steps S14 to S1 are performed in reverse, and these steps S1 to S14 and steps S14 to S1 are repeated. Thus, the cleaning of the side surface Ga, the upper surface Gb, and the side surface Gc, as well as the cleaning of the side surface Gc, the upper surface Gb, and the side surface Ga, are repeatedly performed in gap G. Therefore, as Figure 6 As shown, even if the deposit D removed from the gap G re-attaches to the gap G, the deposit D can be properly removed.

[0079] Furthermore, in the cleaning cycle of this embodiment, steps S1 to S14 and steps S14 to S1 are repeated, but the steps in the cleaning cycle are not limited to these. For example, steps S1 to S14 may be performed after steps S1 to S14, that is, steps S1 to S14 may be repeated.

[0080] In the above implementation methods, such as Figures 8-10 As shown, during the cleaning of gap G, auxiliary gas A (hollow arrow in the figure) can also be supplied to gap G. Figure 8It is to perform the first cleaning under the first condition ( Figure 2 A diagram illustrating the situation. Figure 9 It is to perform the second cleaning under the second condition ( Figure 3 A diagram illustrating the situation. Figure 10 It is to perform the third cleaning under the third condition ( Figure 4 A diagram illustrating the situation.

[0081] For example, auxiliary gas A is supplied from the gas supply section 20 to the upper surface Gb of the gap G, and the auxiliary gas A flows from top to bottom within the gap G. Additionally, during the first cleaning process ( Figure 8 ), during the second cleaning process ( Figure 9 ), the third cleaning process ( Figure 10 In at least one of the processes described above, auxiliary gas A is supplied. Furthermore, the auxiliary gas A causes the adhering material D removed from the gap G to be discharged downwards, and then discharged from the gas outlet 10e. Therefore, it is possible to prevent the adhering material D from re-adhering to the gap G as described above.

[0082] Furthermore, there are no particular limitations on the type of auxiliary gas A, but it is preferable that it is the same type as the cleaning gas. For example, an inert gas can be used as auxiliary gas A, but in this case, the concentration of the cleaning gas in the plasma processing chamber 10 becomes lower, and the plasma generation efficiency may decrease. Regarding this, by using the same type of gas as the cleaning gas for auxiliary gas A, plasma can be generated efficiently.

[0083] In this embodiment, auxiliary gas A is supplied to gap G from top to bottom, but the supply direction is not limited to this. For example, auxiliary gas A can also be supplied to gap G from bottom to top.

[0084] In the above embodiments, when controlling the thickness da of the inner sheath Sa and the thickness db of the outer sheath Sb, both the inner and outer DC voltages are varied. However, it is also possible to fix one DC voltage and vary the other. In this case, the sheath thickness ratio da / db can also be controlled, resulting in control over the incident direction of ions against the gap G.

[0085] In the above embodiments, when controlling the thickness da of the inner sheath Sa and the thickness db of the outer sheath Sb, the self-bias voltages of the inner upper electrode 130 and the outer upper electrode 131 are controlled by varying both the inner and outer DC voltages, but this is not a limitation. For example, when bias RF power from the second RF generation section 31b is supplied to the inner upper electrode 130 and the outer upper electrode 131, these bias RF powers can also be controlled to control the self-bias voltages of the inner upper electrode 130 and the outer upper electrode 131.

[0086] In addition, according to the above-described formula (1) for calculating the thickness of the sheath of plasma, the thickness of the sheath becomes smaller when the plasma density is large, and the thickness of the sheath becomes larger when the plasma density is small. Therefore, it is also possible to control the thickness da of the inner sheath Sa and the thickness db of the outer sheath Sb by controlling the density of plasma formed below the inner upper electrode 130 and the density of plasma formed below the outer upper electrode 131.

[0087] For example, in a case where the source RF power from the first RF generating section 31a is supplied to the inner upper electrode 130 and the outer upper electrode 131, it is also possible to control the plasma density below the inner upper electrode 130 and the plasma density below the outer upper electrode 131 by controlling these source RF powers.

[0088] In addition, for example, in order to control the plasma density, sometimes an electromagnet is provided on the upper surface of the plasma processing chamber 10 to form a magnetic field in the plasma processing space 10s. In this case, it is also possible to control the plasma density below the inner upper electrode 130 and the plasma density below the outer upper electrode 131 by controlling the magnetic field formed by the electromagnet above the inner upper electrode 130 and the magnetic field formed by the electromagnet above the outer upper electrode 131.

[0089] [Cleaning of substrate support section]

[0090] The above-described cleaning method of the embodiments can also be applied when cleaning the minute gap F formed between the electrostatic chuck 1111 and the edge ring 113. Figure 11 is an explanatory diagram showing a case where the gap F is cleaned in a state where the substrate dummy Wd is supported by the substrate support section 11, Figure 12 is an explanatory diagram showing a case where the gap F is cleaned (cleaning without substrate) in a state where the substrate dummy is not supported by the substrate support section 11.

[0091] As Figure 11 and Figure 12As shown, the electrostatic chuck 1111 has a central region 111a for supporting the substrate dummy Wd and a ring-shaped region 111b for supporting the ring assembly 112 (the edge ring 113). The central region 111a is provided protrusively from the ring-shaped region 111b. A gap F is formed between the outer side surface of the portion of the electrostatic chuck 1111 corresponding to the central region 111a and the inner side surface of the edge ring 113. In addition, in the following description, the sheath layer of the plasma generated above the electrostatic chuck 1111 is referred to as the inner side sheath layer Sc, and the sheath layer of the plasma generated above the edge ring 113 is referred to as the outer side sheath layer Sd. In addition, the thickness dc of the inner side sheath layer Sc is the distance from the plasma to the upper surface of the substrate dummy Wd (the electrostatic chuck 1111), and the thickness dd of the outer side sheath layer Sd is the distance from the plasma to the upper surface of the edge ring 113.

[0092] In the cleaning of the gap F as well, the self-bias is controlled to control the thickness dc of the inner side sheath layer Sc and the thickness dd of the outer side sheath layer Sd, respectively, to control the incident direction of the ions with respect to the gap F. That is, the DC voltage applied from the third DC generator 32c to the electrostatic chuck 1111 (hereinafter, referred to as "chuck DC voltage") is controlled to control the self-bias of the substrate dummy Wd or the electrostatic chuck 1111. In addition, the DC voltage applied from the fourth DC generator 32d to the edge ring 113 (hereinafter, referred to as "ring DC voltage") is controlled to control the self-bias of the edge ring 113.

[0093] Figure 11 (a) of FIG. 8 and Figure 12 (a) of FIG. 8 is a diagram of the case where the chuck DC voltage is greater than the ring DC voltage. In the following description, this cleaning condition is referred to as the fourth condition. In this case, the thickness dc of the inner side sheath layer Sc is greater than the thickness dd of the outer side sheath layer Sd. Then, the incident direction (arrow in the drawing) of the ions with respect to the gap F is inclined from the vertical direction to the electrostatic chuck 1111 side, and the ions are incident to the side surface Fa of the inner side upper electrode 130 side of the gap F. Also, this side surface Fa becomes the cleaning target region, and the deposits D attached to this side surface Fa are removed by the ions. In addition, in this case, when the thickness ratio dc / dd of the sheath layer is large, the inclination angle of the ions becomes large.

[0094] Figure 11 (b) of FIG. 8 and Figure 12(b) is an explanatory diagram showing the case where the disk DC voltage is the same as the ring DC voltage. In the following explanation, this cleaning condition will be referred to as the fifth condition. In this case, the thickness dc of the inner sheath Sc is the same as the thickness dd of the outer sheath Sd. Therefore, the incident direction of ions towards the gap F (the arrow in the diagram) becomes vertical, and the ions are incident on the lower surface Fb of the gap F. Furthermore, this lower surface Fb becomes the cleaning target area, and the deposits D attached to this lower surface Fb are removed by the ions.

[0095] Figure 11 (c) and Figure 12 (c) is an explanatory diagram showing the case where the disk DC voltage is less than the ring DC voltage. In the following explanation, this cleaning condition will be referred to as the sixth condition. In this case, the thickness dc of the inner sheath layer Sc is less than the thickness dd of the outer sheath layer Sd. Therefore, the incident direction of ions towards the gap F (the arrow in the diagram) is tilted from the vertical direction towards the edge ring 113 side, and the ions are incident on the side Fc of the gap F near the edge ring 113 side. Furthermore, this side Fc becomes the cleaning target area, and the deposits D attached to this side Fc are removed by the ions. Additionally, in this case, when the sheath thickness ratio dc / dd is small, the tilt angle of the ions becomes larger.

[0096] In this embodiment, the fourth cleaning under the fourth condition is performed sequentially. Figure 11 (a) and Figure 12 (b) and the fifth cleaning under the fifth condition ( Figure 11 (a) and Figure 12 (b) and the sixth cleaning under the sixth condition ( Figure 11 (a) and Figure 12 Figure 11 Figure 12 (b)). In this case, the side surface Fa, the lower surface Fb, and the side surface Fc in the gap F can be cleaned sequentially. Furthermore, by repeating these fourth, fifth, and sixth cleaning processes, the side surface Fa, the lower surface Fb, and the side surface Fc, as well as the side surface Fc, the lower surface Fb, and the side surface Fa, can be repeatedly cleaned in the gap F. This reduces the adhesion of deposits D to the gap F, thereby improving cleaning efficiency.

[0097] Furthermore, in this embodiment, when controlling the thickness dc of the inner sheath layer Sc and the thickness dd of the outer sheath layer Sd, both the DC voltage of the holding disk and the DC voltage of the ring can be varied. However, it is also possible to fix one of the DC voltages and vary the other. In this case, the sheath thickness ratio dc / dd can also be controlled, and as a result, the incident direction of ions against the gap F can be controlled.

[0098] The cleaning of the gap G between the inner upper electrode 130 and the outer upper electrode 131 in the above-described embodiments and the cleaning of the gap F between the electrostatic chuck 1111 and the edge ring 113 can be performed individually, or both can be performed simultaneously.

[0099] In addition, the above-described cleaning (e.g., the fourth to sixth cleanings) can also be performed on the gap formed between the edge ring 113 and the cover ring 114. In this case, the sheath layer of the plasma generated above the edge ring 113 is set as an inner sheath layer, and the sheath layer of the plasma generated above the cover ring 114 is set as an outer sheath layer. Since the DC voltage is applied only to the edge ring 113, the thickness of only the inner sheath layer above the edge ring 113 is variable, but by making the thickness ratio of the inner sheath layer and the outer sheath layer variable, the same effects as in the above-described embodiments can be obtained for the gap formed between the edge ring 113 and the cover ring 114.

[0100] In addition, it can also be that, in the shower head assembly 13, the above-described cleaning (e.g., the first to third cleanings) is performed on the gap formed between the upper electrode and an insulating ring (not shown) provided to the outer periphery of the upper electrode. In this case, the sheath layer of the plasma generated below the upper electrode is set as an inner sheath layer, and the sheath layer of the plasma generated below the insulating ring is set as an outer sheath layer. Since the DC voltage is applied only to the upper electrode, the thickness of only the inner sheath layer below the upper electrode is variable, but by making the thickness ratio of the inner sheath layer and the outer sheath layer variable, the same effects as in the above-described embodiments can be obtained for the gap formed between the upper electrode and the insulating ring.

[0101] It should be considered that the embodiments disclosed herein are illustrative in all aspects and are not restrictive. The above-described embodiments can also be omitted, replaced, changed in various ways without departing from the scope of the appended claims and the spirit thereof. For example, the constituent elements of the above-described embodiments can be combined arbitrarily. According to this arbitrary combination, the effects and advantages of each structural element related to the combination can of course be obtained, and other effects and other advantages that are apparent to those skilled in the art from the description of this specification can also be obtained.

[0102] In addition, the effects described in this specification are merely illustrative or exemplary effects, and are not limiting. That is, the technology related to the present application can achieve other effects apparent to those skilled in the art from the description of this specification in addition to or instead of the above effects.

[0103] Furthermore, the following structure examples also belong to the technical scope of the present disclosure.

[0104] (1) A cleaning method of a plasma processing apparatus, comprising the following steps:

[0105] Step (a): Introducing a clean gas into the chamber of the plasma processing apparatus;

[0106] Step (b) involves generating plasma within the chamber under first conditions to perform a first cleaning; and

[0107] Step (c) involves generating plasma within the chamber under second conditions to perform a second cleaning.

[0108] In the cleaning method of the plasma processing apparatus, at least one of the first condition and the second condition is adjusted such that a first ratio of the thickness of the inner sheath to the thickness of the outer sheath in the sheath of the plasma generated in step (b) is different from a second ratio of the thickness of the inner sheath to the thickness of the outer sheath in the sheath of the plasma generated in step (c).

[0109] (2) The cleaning method of the plasma treatment apparatus according to (1), wherein step (b) and step (c) are repeated.

[0110] (3) A cleaning method for the plasma processing apparatus according to (1) or (2), wherein a step (d) is included, in which the thickness of the plasma sheath is changed from the first ratio to the second ratio in stages.

[0111] (4) A cleaning method for a plasma processing apparatus according to any one of (1) to (3), wherein a step (e) is included in which the thickness of the plasma sheath is changed from the second ratio to the first ratio in stages.

[0112] (5) A cleaning method for a plasma processing apparatus according to any one of (1) to (4), wherein the first cleaning of step (b) and the second cleaning of step (c) are performed on the gap between the inner upper electrode and the outer upper electrode in the plasma processing apparatus.

[0113] (6) The cleaning method of the plasma processing apparatus according to (5), wherein at least one of the first condition and the second condition is adjusted by controlling the self-bias voltage of at least one of the inner upper electrode and the outer upper electrode.

[0114] (7) The cleaning method of the plasma processing apparatus according to (6), wherein at least one of the first condition and the second condition is adjusted by controlling the DC voltage applied to at least one of the inner upper electrode and the outer upper electrode.

[0115] (8) The cleaning method of the plasma processing apparatus according to (5), wherein at least one of the first condition and the second condition is adjusted by controlling the plasma density below at least one of the inner upper electrode and the outer upper electrode.

[0116] (9) The plasma processing apparatus according to any one of (5) to (8), wherein, in at least one of the steps (b) and (c), an auxiliary gas is supplied to the gap.

[0117] (10) The cleaning method of the plasma processing apparatus according to (9), wherein the auxiliary gas is a gas of the same kind as the cleaning gas.

[0118] (11) A cleaning method for a plasma processing apparatus according to any one of (1) to (4), wherein the first cleaning of step (b) and the second cleaning of step (c) are performed on the gap between the electrostatic holding disk and the edge ring in the plasma processing apparatus.

[0119] (12) A cleaning method for a plasma processing apparatus according to any one of (1) to (4), wherein the first cleaning of step (b) and the second cleaning of step (c) are performed on the gap between the edge ring and the cover ring in the plasma processing apparatus.

[0120] (13) A cleaning method for a plasma processing apparatus according to any one of (1) to (4), wherein the first cleaning of step (b) and the second cleaning of step (c) are performed on the gap between the upper electrode in the plasma processing apparatus and the insulating ring disposed on the outer periphery of the upper electrode.

[0121] Explanation of reference numerals in the attached figures

[0122] 1: Plasma processing device; 2: Control unit; 10: Plasma processing chamber; 20: Gas supply unit; 31: RF power supply; W: Substrate.

Claims

1. A cleaning method for a plasma processing device, comprising the following steps: Step (a): Introducing a clean gas into the chamber of the plasma processing apparatus; Step (b) involves generating plasma within the chamber under first conditions to perform a first cleaning; and Step (c) involves generating plasma within the chamber under second conditions to perform a second cleaning. In the cleaning method of the plasma processing apparatus, at least one of the first condition and the second condition is adjusted such that a first ratio of the thickness of the inner sheath to the thickness of the outer sheath in the sheath of the plasma generated in step (b) is different from a second ratio of the thickness of the inner sheath to the thickness of the outer sheath in the sheath of the plasma generated in step (c).

2. The cleaning method for the plasma processing apparatus according to claim 1, wherein, Repeat steps (b) and (c).

3. The cleaning method for the plasma processing apparatus according to claim 1 or 2, wherein, The process includes a step (d) that switches from step (b) to step (c), in which the thickness of the plasma sheath is gradually changed from the first ratio to the second ratio.

4. The cleaning method for the plasma processing apparatus according to claim 1 or 2, wherein, The process includes a step (e) that switches from step (c) to step (b), in which the thickness of the plasma sheath is gradually changed from the second ratio to the first ratio.

5. The cleaning method for the plasma processing apparatus according to claim 1 or 2, wherein, The gap between the inner upper electrode and the outer upper electrode in the plasma processing device is cleaned using the first cleaning step (b) and the second cleaning step (c).

6. The cleaning method for the plasma processing apparatus according to claim 5, wherein, At least one of the first condition and the second condition is adjusted by controlling the self-bias voltage of at least one of the inner upper electrode and the outer upper electrode.

7. The cleaning method for the plasma processing apparatus according to claim 6, wherein, At least one of the first and second conditions is adjusted by controlling the DC voltage applied to at least one of the inner upper electrode and the outer upper electrode.

8. The cleaning method for the plasma processing apparatus according to claim 5, wherein, At least one of the first and second conditions is adjusted by controlling the plasma density below at least one of the inner upper electrode and the outer upper electrode.

9. The cleaning method for the plasma processing apparatus according to claim 5, wherein, In at least one of steps (b) and (c), auxiliary gas is supplied to the gap.

10. The cleaning method for the plasma processing apparatus according to claim 9, wherein, The auxiliary gas is the same type of gas as the cleaning gas.

11. The cleaning method for the plasma processing apparatus according to claim 1 or 2, wherein, The gap between the electrostatic holding disk and the edge ring in the plasma processing apparatus is cleaned using the first cleaning step (b) and the second cleaning step (c).

12. The cleaning method for the plasma processing apparatus according to claim 1 or 2, wherein, The gap between the edge ring and the cover ring in the plasma processing device is cleaned using the first cleaning step (b) and the second cleaning step (c).

13. The cleaning method for the plasma processing apparatus according to claim 1 or 2, wherein, The gap between the upper electrode in the plasma processing apparatus and the insulating ring disposed on the outer periphery of the upper electrode is cleaned in step (b) as well as in step (c) as the second cleaning.

14. A plasma processing apparatus, comprising: chamber; A gas supply unit that supplies clean gas into the chamber; A plasma generation unit for generating plasma from the clean gas within the chamber; and Control Department in, The control unit controls the gas supply unit and the plasma generation unit to perform the following steps: Step (a): Introduce the cleaning gas into the chamber; Step (b) involves generating plasma within the chamber under first conditions to perform a first cleaning; and Step (c) involves generating plasma within the chamber under second conditions to perform a second cleaning. The control unit adjusts at least one of the first condition and the second condition such that a first ratio of the thickness of the inner sheath to the thickness of the outer sheath in the sheath of the plasma generated in step (b) is different from a second ratio of the thickness of the inner sheath to the thickness of the outer sheath in the sheath of the plasma generated in step (c).

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