CN119013769A

CN119013769A - Method for cleaning plasma processing apparatus

Info

Publication number: CN119013769A
Application number: CN202280094526.3A
Authority: CN
Inventors: 滨康孝; 新藤信明
Original assignee: Tokyo Electron Ltd
Current assignee: Tokyo Electron Ltd
Priority date: 2022-02-02
Filing date: 2022-02-02
Publication date: 2024-11-22
Also published as: KR20240156370A; WO2023148861A1

Abstract

The cleaning method of the plasma processing apparatus of the present invention comprises: a step of carrying out plasma treatment on a product substrate on a carrying table provided in a chamber; and a step of placing a first dummy substrate having a smaller diameter than the product substrate on the stage, generating plasma in the chamber, and performing a first dry cleaning of cleaning the stage.

Description

Method for cleaning plasma processing apparatus

Technical Field

The present invention relates to a method for cleaning a plasma processing apparatus.

Background

Patent document 1 discloses a method of dry cleaning the inside of a vacuum processing chamber of a vacuum processing apparatus. The dry cleaning is performed in a state in which a dummy wafer (dummy wafer) is placed on a sample stage in the vacuum processing chamber.

Patent document 2 discloses a method of dry cleaning the interior of a plasma processing chamber of a plasma processing system. The dry cleaning is so-called waferless dry cleaning, and is performed without placing a dummy wafer on a susceptor in a plasma processing chamber.

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open No. 5-74739

Patent document 2: japanese patent application laid-open No. 2019-511843

Disclosure of Invention

Technical problem to be solved by the invention

The technique of the present invention suitably performs dry cleaning of a stage on which a substrate is placed in a chamber of a plasma processing apparatus.

Technical scheme for solving technical problems

One embodiment of the present invention is a method for cleaning a plasma processing apparatus, including: a step of carrying out plasma treatment on a product substrate on a carrying table provided in a chamber; and a step of placing a first dummy substrate having a smaller diameter than the product substrate on the stage, and performing a first dry cleaning of generating plasma in the chamber to clean the stage.

Effects of the invention

According to the present invention, the dry cleaning of the stage on which the substrate is placed can be performed appropriately in the chamber of the plasma processing apparatus.

Drawings

Fig. 1 is a vertical sectional view showing a schematic configuration of a plasma processing apparatus according to the present embodiment.

Fig. 2 is a longitudinal sectional view showing a schematic configuration of the electrostatic chuck and the edge ring according to the present embodiment.

Fig. 3 is a plan view showing a schematic structure of the electrostatic chuck and the edge ring according to the present embodiment.

Fig. 4 is an explanatory diagram showing a case of dry cleaning using a dummy wafer.

Fig. 5 is a flowchart showing main steps of wafer processing according to the first embodiment.

Fig. 6 is an explanatory diagram showing a series of flows of wafer processing according to the first embodiment using a wafer.

Fig. 7 is an explanatory diagram showing the position of a wafer during dry cleaning according to the first embodiment.

Fig. 8 is an explanatory diagram of a first position in the first embodiment.

Fig. 9 is an explanatory diagram of first to fourth positions in the first embodiment.

Fig. 10 is an explanatory diagram showing a series of flows of wafer processing according to a modification of the first embodiment using wafers.

Fig. 11 is an explanatory diagram showing a series of flows of wafer processing according to a modification of the first embodiment using wafers.

Fig. 12 is an explanatory diagram showing a series of flows of wafer processing according to a modification of the first embodiment using a wafer.

Fig. 13 is an explanatory diagram showing a series of flows of wafer processing according to a modification of the first embodiment using a wafer.

Fig. 14 is an explanatory diagram showing a state of a first dummy wafer in a modification of the first embodiment.

Fig. 15 is a longitudinal sectional view showing a schematic structure of a small-diameter dummy wafer, an electrostatic chuck, and an edge ring according to a second embodiment.

Fig. 16 is a plan view showing a schematic structure of a small-diameter dummy wafer, an electrostatic chuck, and an edge ring according to a second embodiment.

Fig. 17 is an explanatory diagram showing a series of flows of wafer processing according to the second embodiment using a wafer.

Fig. 18 is an explanatory diagram showing a series of flows of wafer processing according to a modification of the second embodiment using wafers.

Fig. 19 is an explanatory diagram showing a series of flows of wafer processing according to a modification of the second embodiment using wafers.

Detailed Description

In a manufacturing process of a semiconductor device, a semiconductor wafer (hereinafter, referred to as a "wafer") is subjected to plasma treatment. In the plasma processing, a process gas is excited to generate plasma, and a wafer is processed by the plasma.

The plasma treatment is performed in a plasma treatment apparatus. The plasma processing apparatus generally includes a chamber, a stage, and a high Frequency (RF) power source. In one example, the high frequency power supply includes a first high frequency power supply and a second high frequency power supply. The first high-frequency power supply supplies first high-frequency electric power to generate plasma of gas in the chamber. The second high-frequency power supply supplies a second high-frequency electric power for bias to the lower electrode to introduce ions into the wafer. The chamber divides its interior space into a processing space for generating plasma. The mounting table is disposed in the chamber. The stage has a lower electrode and an electrostatic chuck. The electrostatic chuck is disposed on the lower electrode. An edge ring is disposed on the electrostatic chuck so as to surround a wafer placed on the electrostatic chuck. The edge ring is provided to control the shape of the sheath layer near the end of the wafer and to improve the uniformity of plasma treatment on the wafer.

In the plasma treatment, a reaction product is generated. The reaction product adheres to the inner wall of the chamber, the edge ring, and the like, and is deposited as a deposit (hereinafter referred to as "deposit"). The deposits are the cause of foreign matter (hereinafter referred to as "particles") and may cause deterioration of the yield of the product and reduction of the operating time of the apparatus. Therefore, in order to remove the deposits, dry cleaning using plasma is performed inside the chamber. That is, in dry cleaning, a dry cleaning gas is excited to generate plasma, and the plasma is used to remove deposits. Specifically, dry cleaning removes deposits by chemical reaction using radicals and physical reaction (sputtering) using ions.

The dry cleaning may be performed in a state in which a dummy wafer is placed on a stage as disclosed in patent document 1. As disclosed in patent document 2, there is also a case where dry cleaning is performed in a state where a dummy wafer is not placed on a placing table (waferless dry cleaning).

In dry cleaning using a dummy wafer, radicals and ions are blocked by the dummy wafer, and a region where it is difficult to supply the radicals and ions (a region where it is difficult to enter the radicals and ions) is generated. In particular, when the second high-frequency electric power (bias electric power) is supplied to the lower electrode of the stage, ions travel straight toward the dummy wafer, and therefore the sputtering efficiency of the ions is significantly reduced in the region shielded by the dummy wafer. Therefore, it is not possible to sufficiently remove deposits (for example, si-containing deposits of metals) which are difficult to remove by chemical reaction using radicals.

In the dry cleaning without using the dummy wafer, the dummy wafer is not placed on the stage (electrostatic chuck), and therefore ions are directly incident on the surface of the stage. Therefore, when the bias electric power is increased, the mounting table is damaged. Therefore, it is necessary to reduce the bias electric power, and the sputtering efficiency by ions is reduced. Furthermore, deposits that are difficult to remove (e.g., si, metal-containing deposits) cannot be sufficiently removed by chemical reactions using radicals.

The technique of the present invention suitably performs dry cleaning of a stage on which a substrate is placed in a chamber of a plasma processing apparatus. Hereinafter, a plasma processing apparatus and a dry cleaning method for the plasma processing apparatus according to the present embodiment will be described with reference to the accompanying drawings. In the present specification and the drawings, elements having substantially the same functional configuration are denoted by the same reference numerals, and repetitive description thereof will be omitted.

< Plasma processing apparatus >

First, a plasma processing apparatus according to the present embodiment will be described. Fig. 1 is a longitudinal sectional view showing a schematic configuration of a plasma processing apparatus 1. The plasma processing apparatus 1 is a capacitively-coupled plasma processing apparatus. In the plasma processing apparatus 1, a product wafer W, which is a product substrate, is subjected to plasma processing. The product wafer W is a wafer subjected to a desired plasma treatment, and is, for example, a wafer having a pattern formed on the surface thereof. The product wafer W is, for example, a silicon wafer having a diameter of 300 mm. The plasma treatment is not particularly limited, and may be, for example, etching treatment, film formation treatment, diffusion treatment, or the like.

As shown in fig. 1, the plasma processing apparatus 1 has a chamber 10 having a substantially cylindrical shape. The chamber 10 is divided inside thereof into a processing space S in which plasma is generated. The chamber 10 is made of, for example, aluminum. The chamber 10 is connected to ground potential. A film having plasma resistance is formed on the inner wall surface of the chamber 10, that is, the wall surface dividing the processing space S. The film may be a film formed by anodic oxidation treatment or a ceramic film such as a film formed of yttria.

A stage 11 on which a product wafer W is placed is housed in the chamber 10. The mounting table 11 has a lower electrode 12, an electrostatic chuck 13, and an edge ring 14. An electrode plate (not shown) made of, for example, aluminum may be provided on the back surface side of the lower electrode 12.

The lower electrode 12 is made of conductive metal, for example, aluminum, and has a substantially disk shape.

A refrigerant flow path 15a is formed inside the lower electrode 12. The refrigerant is supplied to the refrigerant flow path 15a from a cooling unit (not shown) provided outside the chamber 10 via the refrigerant inlet pipe 15 b. The refrigerant supplied to the refrigerant flow path 15a returns to the cooling unit via the refrigerant outlet flow path 15 c. By circulating a refrigerant, such as cooling water, in the refrigerant flow path 15a, the electrostatic chuck 13, the edge ring 14, and the product wafer W can be cooled to a desired temperature.

An electrostatic chuck 13 is disposed on the lower electrode 12. The electrostatic chuck 13 is a member capable of holding both the product wafer W and the edge ring 14 by suction using electrostatic force. The surface of the central portion of the electrostatic chuck 13 is formed higher than the surface of the outer peripheral portion. The surface of the center portion of the electrostatic chuck 13 serves as a wafer mounting surface on which the product wafer W is mounted, and the surface of the outer peripheral portion of the electrostatic chuck 13 serves as an edge ring mounting surface on which the edge ring 14 is mounted. Further, details concerning the structure of the electrostatic chuck 13 will be described later.

A first electrode 16a for sucking and holding the product wafer W is provided in the center of the inside of the electrostatic chuck 13. Inside the electrostatic chuck 13, a second electrode 16b for sucking and holding the edge ring 14 is provided at the outer peripheral portion. The electrostatic chuck 13 has a structure in which electrodes 16a and 16b are sandwiched between insulating materials.

A dc voltage from a dc power supply (not shown) is applied to the first electrode 16 a. The product wafer W is held by suction on the surface of the central portion of the electrostatic chuck 13 by the electrostatic force generated thereby. Similarly, a dc voltage from a dc power supply (not shown) is applied to the second electrode 16 b. The edge ring 14 is held by suction on the surface of the outer peripheral portion of the electrostatic chuck 13 by the electrostatic force generated thereby.

The edge ring 14 is an annular member disposed so as to surround the product wafer W placed on the surface of the center portion of the electrostatic chuck 13. The edge ring 14 is provided to improve uniformity of plasma treatment. Accordingly, the edge ring 14 is made of a material appropriately selected according to plasma treatment, and can be made of quartz, si, siC, or the like, for example. Further, details regarding the structure of the edge ring 14 will be described later.

The mounting table 11 configured as described above is fastened to a substantially cylindrical support member 17 provided at the bottom of the chamber 10. The support member 17 is made of an insulator such as ceramic or quartz.

Although not shown, the mounting table 11 may include a temperature adjustment module configured to adjust at least one of the electrostatic chuck 13, the edge ring 14, and the product wafer W to a desired temperature. The temperature regulation module may include a heater, a flow path, or a combination thereof. A temperature control fluid such as a refrigerant or a heat transfer gas flows through the flow path.

A lifter 20 for lifting and lowering the product wafer W relative to the mounting table 11 is provided below the mounting table 11 and inside the supporting member 17. The lifter 20 includes a lifter pin 21, a support member 22, and a driving portion 23.

The lift pin 21 is a columnar member that is lifted and lowered so as to extend from and retract into the surface of the center portion of the electrostatic chuck 13, and is formed of, for example, ceramic. The lift pins 21 are provided at intervals of three or more in the circumferential direction of the electrostatic chuck 13, that is, in the circumferential direction of the surface. The lift pins 21 are provided at equal intervals along the circumferential direction, for example. The lift pins 21 are provided so as to extend in the up-down direction.

The lift pin 21 is inserted into a through hole 24 extending downward from the surface of the central portion of the electrostatic chuck 13 to reach the bottom surface of the lower electrode 12. That is, the through hole 24 is formed so as to penetrate the center portion of the electrostatic chuck 13 and the lower electrode 12.

The support member 22 supports the plurality of lift pins 21. The driving unit 23 generates a driving force for lifting and lowering the support member 22, and lifts and lowers the plurality of lift pins 21. The driving unit 23 includes a motor (not shown) that generates the driving force.

The plasma processing apparatus 1 further includes a first high Frequency (RF) power supply 30, a second high Frequency power supply 31, a first matcher 32, and a second matcher 33. The first high-frequency power supply 30 and the second high-frequency power supply 31 are connected to the lower electrode 12 via a first matcher 32 and a second matcher 33, respectively.

The first high-frequency power supply 30 is a power supply that generates high-frequency electric power for plasma generation. The high-frequency power HF having a frequency of 27MHz to 100MHz, in one example 40MHz, can be supplied from the first high-frequency power supply 30 to the lower electrode 12. The first matching unit 32 has a circuit for matching the output impedance of the first high-frequency power supply 30 with the input impedance of the load side (lower electrode 12 side). The first high-frequency power supply 30 may not be electrically connected to the lower electrode 12, but may be connected to the showerhead 40 as an upper electrode via the first matching unit 32.

The second high-frequency power supply 31 generates high-frequency electric power (bias electric power) LF for introducing ions into the product wafer W, and supplies the high-frequency electric power LF to the lower electrode 12. The frequency of the high-frequency electric power LF may be in the range of 400kHz to 13.56MHz, and in one example, 400kHz. The second matching unit 33 has a circuit for matching the output impedance of the second high-frequency power supply 31 with the input impedance of the load side (lower electrode 12 side). In addition, a DC (Direct Current) pulse generating section may be used instead of the second high-frequency power supply 31.

A shower head 40 is provided above the mounting table 11 so as to face the mounting table 11. The showerhead 40 includes an electrode plate 41 disposed facing the processing space S and an electrode support 42 provided above the electrode plate 41. The electrode plate 41 and the lower electrode 12 function as a pair of upper electrodes. As will be described later, when the first high-frequency power supply 30 is electrically connected to the lower electrode 12, the showerhead 40 is connected to the ground potential. The showerhead 40 is supported on an upper portion (ceiling surface) of the chamber 10 via an insulating shielding member 43.

The electrode plate 41 is formed with a plurality of gas outlets 41a for supplying a process gas supplied from a gas diffusion chamber 42a described later to the process space S. The electrode plate 41 is made of, for example, a conductor or a semiconductor having low resistivity and generating little joule heat.

The electrode support 42 supports the electrode plate 41 in a detachable manner with respect to the electrode plate 41. The electrode support 42 has a structure in which a film having plasma resistance is formed on the surface of a conductive material such as aluminum. The film may be a film formed by anodic oxidation treatment or a ceramic film such as a film formed of yttria. A gas diffusion chamber 42a is formed in the electrode support 42. A plurality of gas flow holes 42b communicating with the gas ejection holes 41a are formed from the gas diffusion chamber 42a. The gas diffusion chamber 42a is formed with a gas introduction hole 42c connected to a gas supply pipe 53 described later.

The gas supply source group 50 for supplying the process gas to the gas diffusion chamber 42a is connected to the electrode support 42 via the flow control device group 51, the valve group 52, the gas supply pipe 53, and the gas introduction hole 42 c.

The gas supply source group 50 has a plurality of gas supply sources required for plasma processing or dry cleaning. The flow control device group 51 includes a plurality of flow controllers and the valve group 52 includes a plurality of valves. The plurality of flow controllers of the flow control device group 51 are each a mass flow controller or a pressure control type flow controller. In the plasma processing apparatus 1, the process gas of one or more gas supply sources selected from the gas supply source group 50 is supplied to the gas diffusion chamber 42a via the flow control device group 51, the valve group 52, the gas supply pipe 53, and the gas introduction hole 42 c. Then, the process gas supplied to the gas diffusion chamber 42a is supplied into the process space S in a spray-like dispersion through the gas flow holes 42b and the gas discharge ports 41 a.

In the plasma processing apparatus 1, a deposition shield 60 is removably provided along the inner wall of the chamber 10. The deposit shielding member 60 is constituted by, for example, coating an aluminum material with ceramics such as yttrium oxide, and suppresses adhesion of deposits to the inner wall of the chamber 10. In the same manner, a deposit shade 61 is detachably provided on the outer peripheral surface of the support member 17, which is the surface facing the deposit shade 60.

A baffle 62 is provided at the bottom of the chamber 10 between the inner wall of the chamber 10 and the support member 17. The baffle 62 is formed by coating ceramic such as yttria with an aluminum material. The baffle 62 has a plurality of through holes. The processing space S communicates with the exhaust port 63 via the baffle plate 62. The exhaust port 63 is connected to an exhaust device 64 such as a vacuum pump, for example, and the inside of the processing space S can be depressurized by the exhaust device 64.

A carry-in/carry-out port 65 for the product wafer W is formed in a side wall of the chamber 10, and the carry-in/carry-out port 65 is openable and closable by a shutter 66.

In the present embodiment, the dry cleaning unit includes the lower electrode 12, the second high-frequency power supply 31, the gas supply source group 50, and the like, and as will be described later, the dry cleaning gas is excited to generate plasma to dry clean the inside of the chamber 10.

The above plasma processing apparatus 1 is provided with a control unit 70. The control unit 70 is a computer including, for example, a CPU, a memory, and the like, and has a program storage unit (not shown). The program storage unit stores a program for controlling plasma processing in the plasma processing apparatus 1. The program may be recorded on a computer-readable storage medium, and installed from the storage medium to the control unit 70. The control section 70 controls the conveyance of the substrate (including the up-and-down movement of the substrate by the lifter 20), the plasma processing of the substrate, and the execution of dry cleaning in the chamber 10.

< Method of plasma treatment >

Next, plasma processing performed using the plasma processing apparatus 1 configured as described above will be described.

First, a product wafer W is fed into the chamber 10, and the product wafer W is placed on the electrostatic chuck 13. At this time, the product wafer W is placed on the electrostatic chuck 13 so that the center of the product wafer W is positioned at the same position as the center of the electrostatic chuck 13 in a plan view. The position of the product wafer W is a processing position in the present invention. Thereafter, by applying a direct current voltage to the first electrode 16a of the electrostatic chuck 13, the product wafer W is electrostatically attracted and held to the electrostatic chuck 13 by the coulomb force. After the product wafer W is fed, the interior of the chamber 10 is depressurized to a desired vacuum degree by the evacuation device 64.

Then, the process gas is supplied from the gas supply source group 50 to the process space S through the showerhead 40. Further, the high-frequency power HF for generating plasma is supplied to the lower electrode 12 by the first high-frequency power supply 30, and the process gas is excited to generate plasma. At this time, the second high-frequency power supply 31 may be used to supply the high-frequency electric power LF for ion introduction. Then, the product wafer W is subjected to plasma treatment by the action of the generated plasma.

When the plasma processing is ended, first, the supply of the high-frequency electric power HF from the first high-frequency power supply 30 and the supply of the processing gas by the gas supply source group 50 are stopped. In addition, in the case where the high-frequency electric power LF is supplied during the plasma processing, the supply of the high-frequency electric power LF is also stopped. Then, the supply of the heat transfer gas to the back surface of the product wafer W is stopped, and the suction and holding of the product wafer W by the electrostatic chuck 13 are stopped.

Thereafter, the product wafer W is sent out from the chamber 10, and the series of plasma treatments on the product wafer W is ended.

Further, in the plasma processing, the high-frequency electric power HF from the first high-frequency power supply 30 is sometimes not used, but only the high-frequency electric power LF from the second high-frequency power supply 31 is used to generate plasma.

< Electrostatic chuck and edge Ring >

Next, the main configurations of the electrostatic chuck 13 and the edge ring 14 will be described. Fig. 2 is a longitudinal sectional view showing a schematic configuration of the electrostatic chuck 13 and the edge ring 14. Fig. 3 is a plan view showing a schematic structure of the electrostatic chuck 13 and the edge ring 14.

As shown in fig. 2, the electrostatic chuck 13 is configured by integrating a central portion 100 having a surface 100a on which a product wafer W is placed and an outer peripheral portion 101 having a surface 101a on which an edge ring 14 is placed. The central portion 100 is provided so as to protrude from the outer peripheral portion 101, and a surface 100a of the central portion 100 is higher than a surface 101a of the outer peripheral portion 101.

The center portion 100 of the electrostatic chuck 13 is formed to have a smaller diameter than the product wafer W, for example, and when the product wafer W is placed on the surface 100a, the peripheral edge portion of the product wafer W protrudes from the center portion 100 of the electrostatic chuck 13.

The center portion 100 and the outer peripheral portion 101 of the electrostatic chuck 13 of the present embodiment are integrally formed, but the center portion 100 and the outer peripheral portion 101 may be separated. The electrostatic chuck 13 of the present embodiment has the central portion 100 and the outer peripheral portion 101, but the outer peripheral portion 101 may be omitted. In this case, the edge ring 14 is supported by another support member (not shown) without being placed on the electrostatic chuck 13.

The edge ring 14 is provided so as to surround the product wafer W placed on the surface 100 a. The edge ring 14 is integrally constituted by a first ring portion 110 having an annular shape and a second ring portion 111 having an annular shape. The first ring portion 110 and the second ring portion 111 are disposed on concentric circles, respectively, and the second ring portion 111 is disposed radially outward of the first ring portion 110.

The surface 110a of the first ring portion 110 is lower than the surface 100 a. The surface 111a of the second ring portion 111 is higher than the surface 100a, for example, the same height as the surface Wa of the product wafer W mounted on the surface 100a or higher than the surface Wa of the product wafer W. In addition, the inner peripheral portion of the surface 111a is inclined toward the surface 110a (radially inward).

The inner diameter of the first ring portion 110 is larger than the diameter of the central portion 100 and smaller than the diameter of the product wafer W. The inner diameter of the second ring portion 111 is larger than the diameter of the product wafer W. Further, the first ring portion 110 is configured to be bored into a lower side of a peripheral edge portion of the product wafer W protruding from the central portion 100 of the electrostatic chuck 13. That is, as shown in fig. 2 and 3, a region which overlaps with the product wafer W in a plan view and becomes a shielding portion of the product wafer W is formed on the surface 110a of the first ring portion 110. In the following description, a region to be a shielding portion of the product wafer W is referred to as a shadow region a.

< Characterization of Dry cleaning Using dummy wafer >

In the plasma treatment, a reaction product is generated as described above. The reaction products adhere to the edge ring 14 or the like and accumulate as a deposit. Accordingly, in order to remove the deposits, dry cleaning using plasma is performed inside the chamber 10. Dry cleaning removes deposits by chemical reaction using radicals and physical reaction (sputtering) using ions. In a chemical reaction using radicals, for example, carbon-based deposits can be removed. In addition, in the physical reaction using ions, for example, deposits containing Si and metals can be removed.

In the present embodiment, dry cleaning is performed using a dummy wafer. However, in this case, radicals and ions are blocked by the dummy wafer, and a region where it is difficult to supply the radicals and ions (a region where it is difficult to enter the radicals and ions) is generated. Hereinafter, this area where dry cleaning is difficult will be described with reference to fig. 4. Fig. 4 is an explanatory diagram showing a case of dry cleaning using the dummy wafer D. In fig. 4, arrows indicate the flow of ions N. In addition, the flow of radicals is omitted in fig. 4 for ease of understanding of the technique. Further, the dummy wafer D is a wafer having the same diameter as the product wafer W. The dummy wafer D is a wafer on which no pattern is formed, and is a so-called bare silicon wafer.

As shown in fig. 4, at the time of dry cleaning, ions N are supplied to the surfaces 110a, 111a of the edge ring 14, and deposits adhering to the surfaces 110a, 111a are removed. However, the ions N are difficult to be supplied to the shadow region a which becomes a shielding portion of the dummy wafer D in a plan view. When high-frequency electric power LF (bias electric power) is supplied to the lower electrode 12, the ions N linearly advance toward the dummy wafer D, and therefore the efficiency of sputtering by the ions N is significantly reduced in the shadow region a shielded by the dummy wafer D. Therefore, it is impossible to sufficiently remove deposits (e.g., si, metal-containing deposits) that are difficult to remove by chemical reaction using radicals. In addition, the radicals are also difficult to supply to the shadow region a, which becomes a shielding portion of the dummy wafer D, and the deposits cannot be removed sufficiently.

Therefore, in the dry cleaning method according to the first embodiment, dummy cleaning (dummy cleaning) of the shadow area a is performed by shifting the position of the dummy wafer D with respect to the mounting table 11 (edge ring 14). In the dry cleaning method according to the second embodiment, a wafer having a smaller diameter than the product wafer W (hereinafter referred to as a "small-diameter dummy wafer") is used as the dummy wafer to perform the dummy cleaning of the shadow area a.

< Dry cleaning method of the first embodiment >

The dry cleaning method of the first embodiment will be described. In the first embodiment, a description will be given of plasma processing for the product wafer W and dry cleaning using the dummy wafer D. In the following description, these plasma processing and dry cleaning are collectively referred to as wafer processing. Fig. 5 is a flowchart showing main steps of wafer processing according to the first embodiment. Fig. 6 is an explanatory diagram showing a series of flows of wafer processing according to the first embodiment using a wafer. Fig. 7 is an explanatory diagram showing the position of a wafer during dry cleaning according to the first embodiment.

In the first embodiment, as will be described later, the dry cleaning is performed using four dummy wafers D1 to D4, but these first to fourth dummy wafers D1 to D4 have the same diameter as the product wafer W. In the first embodiment, the first to fourth dummy wafers D1 to D4 are different dummy wafers. However, the first to fourth dummy wafers D1 to D4 may be the same dummy wafer.

(Step S11)

In step S11, plasma processing is continuously performed on a batch of, for example, 25 product wafers W. The plasma processing method for each product wafer W is as described above.

(Step S12)

In step S12, a first dry cleaning is performed using the first dummy wafer D1. Specifically, first, the first dummy wafer D1 is fed into the chamber 10, and the first dummy wafer D1 is disposed above the electrostatic chuck 13. At this time, as shown in fig. 7 (a), the first dummy wafer D1 is arranged such that the center C1 of the first dummy wafer D1 is offset toward the Y-axis positive direction side from the center C of the electrostatic chuck 13 in a plan view. The position of the first dummy wafer D1 is the first position in the present invention. In this case, the first shadow area A1 on the negative Y-axis direction side of the shadow area a of the edge ring 14 is exposed without overlapping the first dummy wafer D1 in a plan view.

The first position where the first dummy wafer D1 is arranged will be described in more detail. As shown in fig. 8, one end D1a of the first dummy wafer D1 is located between the inner peripheral end of the edge ring 14 and the outer peripheral end of the central portion 100 of the electrostatic chuck 13. The other end D1b of the first dummy wafer D1 is located radially outward of the inner peripheral end of the edge ring 14. Then, in the edge ring 14, the shadow area A1 on the one end D1a side is exposed without overlapping the first dummy wafer D1.

Then, the lifter 20 supporting the first dummy wafer D1 is lowered and placed on the electrostatic chuck 13. Thereafter, by applying a direct current voltage to the first electrode 16a of the electrostatic chuck 13, the first dummy wafer D1 is electrostatically attracted and held to the electrostatic chuck 13 by the coulomb force. After the first dummy wafer D1 is fed, the interior of the chamber 10 is depressurized to a desired vacuum degree by the evacuation device 64.

Then, dry cleaning gas is supplied from the gas supply source group 50 to the processing space S through the showerhead 40. The dry cleaning gas may contain, for example, oxygen, an oxygen-containing gas, HCl, F ₂、Cl₂, hydrogen, nitrogen, argon, SF ₆、C₂F₆、NF₃、CF₄, or a mixture of 2 or more of these gases. Further, high-frequency electric power is supplied to the lower electrode 12 by the first high-frequency power supply 30 and/or the second high-frequency power supply 31. Then, the dry cleaning gas is excited to generate plasma, and deposits inside the chamber 10 are removed by chemical reaction using radicals and physical reaction (sputtering) using ions. At this time, ions are also supplied to the first shadow zone A1 exposed from the first dummy wafer D1, and the deposits adhering to the first shadow zone A1 are removed. Thus, the first dry cleaning is performed.

When the first dry cleaning is finished, first, the supply of the high-frequency electric power from the first high-frequency power source 30 and/or the second high-frequency power source 31 and the supply of the process gas by the gas supply source group 50 are stopped. Then, the suction holding of the first dummy wafer D1 by the electrostatic chuck 13 is stopped.

Thereafter, the first dummy wafer D1 is sent out from the chamber 10, and the first dry cleaning using the first dummy wafer D1 is completed.

(Step S13)

In step S13, plasma processing is continuously performed on the next lot, for example, 25 product wafers W. This step S34 is the same as step S11.

(Step S14)

In step S14, a second dry cleaning is performed using the second dummy wafer D2. Specifically, first, the second dummy wafer D2 is disposed above the electrostatic chuck 13. At this time, as shown in fig. 7 (b), the second dummy wafer D2 is arranged such that the center C2 of the second dummy wafer D2 is offset to the X-axis positive direction side from the center C of the electrostatic chuck 13 in a plan view. The position of the second dummy wafer D2 is the second position in the present invention. In this case, the second shadow area A2 on the X-axis negative direction side of the shadow area a of the edge ring 14 is exposed without overlapping the second dummy wafer D2 in a plan view.

Next, the second dummy wafer D2 is placed on the electrostatic chuck 13, and is then sucked and held by the electrostatic chuck 13. The subsequent dry cleaning method is the same as the first dry cleaning of step S12. That is, the deposition inside the chamber 10 is removed using plasma (including radicals and ions) obtained by exciting the dry cleaning gas. At this time, the deposit adhering to the second shadow zone A2 exposed from the second dummy wafer D2 is also removed. Thus, the second dry cleaning is performed.

(Step S15)

In step S15, plasma processing is continuously performed on the next lot, for example, 25 product wafers W. This step S34 is the same as step S11.

(Step S16)

In step S16, a third dry cleaning is performed using the third dummy wafer D3. Specifically, first, a third dummy wafer D3 is disposed above the electrostatic chuck 13. At this time, as shown in fig. 7 (C), the third dummy wafer D3 is arranged such that the center C3 of the third dummy wafer D3 is offset to the Y-axis negative direction side from the center C of the electrostatic chuck 13 in a plan view. The position of the third dummy wafer D3 is a third position in the present invention. In this case, the third shadow area A3 on the Y-axis positive direction side of the shadow area a of the edge ring 14 is exposed without overlapping the third dummy wafer D3 in a plan view.

Next, the third dummy wafer D3 is placed on the electrostatic chuck 13, and is then sucked and held by the electrostatic chuck 13. The subsequent dry cleaning method is the same as the first dry cleaning of step S12. That is, the deposition inside the chamber 10 is removed using plasma (including radicals and ions) obtained by exciting the dry cleaning gas. At this time, the deposit adhering to the third shadow zone A3 exposed from the third dummy wafer D3 is also removed. Thus, the third dry cleaning is performed.

(Step S17)

In step S17, plasma processing is continuously performed on the next lot, for example, 25 product wafers W. This step S34 is the same as step S11.

(Step S18)

In step S18, a fourth dry cleaning is performed using the fourth dummy wafer D4. Specifically, first, a fourth dummy wafer D4 is disposed above the electrostatic chuck 13. At this time, as shown in fig. 7 (D), the fourth dummy wafer D4 is arranged such that the center C4 of the fourth dummy wafer D4 is offset to the X-axis negative direction side from the center C of the electrostatic chuck 13 in a plan view. The position of the fourth dummy wafer D4 is the fourth position in the present invention. In this case, the fourth shadow area A4 on the X-axis positive direction side of the shadow area a of the edge ring 14 is exposed without overlapping the fourth dummy wafer D4 in a plan view.

Next, the fourth dummy wafer D4 is placed on the electrostatic chuck 13, and is then sucked and held by the electrostatic chuck 13. The subsequent dry cleaning method is the same as the first dry cleaning of step S12. That is, the deposition inside the chamber 10 is removed using plasma (including radicals and ions) obtained by exciting the dry cleaning gas. At this time, the deposit adhering to the fourth shadow zone A4 exposed from the fourth dummy wafer D4 is also removed. Thus, the fourth dry cleaning is performed.

After step S18, steps S11 to S18 are repeated, for example.

As described above, in the first embodiment, by performing the first to fourth dry cleaning, the deposits adhering to the first to fourth shadow areas A1 to A4 can be removed. Therefore, as shown in fig. 4, the deposit can be properly removed even in the shadow area a, which has conventionally been a shadow part of the dummy wafer D and is unable to remove the deposit. In the first embodiment, the portions other than the shadow area a are exposed on the surfaces 110a and 111a of the edge ring 14, and the deposits adhering to the portions can be removed appropriately. Therefore, the deposits can be removed over the entire surfaces 110a, 111a of the edge ring 14, and thus the generation of particles can be suppressed, and the yield of products can be improved. In addition, the operating time of the plasma processing apparatus 1 can be prolonged, and the inter-cleaning average time (MTBC: mean Time Between Cleaning) associated with the plasma processing apparatus can be prolonged.

Conventionally, when dry cleaning is performed using a dummy wafer, it has been required to dispose the dummy wafer at a position that is accurate with respect to the electrostatic chuck 13, that is, at a position where the center of the dummy wafer coincides with the center of the electrostatic chuck 13 in a plan view. Therefore, as in the first embodiment, the intentional arrangement of dummy wafers D1 to D4 at a position shifted from the electrostatic chuck 13 is an extremely novel technical idea that is not known in the prior art.

As described above, in the first embodiment, the first to fourth dry cleaning is performed in a state where the first to fourth dummy wafers D1 to D4 are arranged at the first to fourth positions, respectively. Fig. 9 is an explanatory diagram showing the first to fourth positions. In fig. 9, a first line L1 is a line connecting the center C of the electrostatic chuck 13 and the center C1 of the first dummy wafer D1. The second line L2 is a line connecting the center C of the electrostatic chuck 13 and the center C2 of the second dummy wafer D2. The third line L3 is a line connecting the center C of the electrostatic chuck 13 and the center C3 of the third dummy wafer D3. The fourth line segment L4 is a line segment connecting the center C of the electrostatic chuck 13 and the center C4 of the fourth dummy wafer D4. The first angle θ1 is an angle formed by the first line segment L1 and the second line segment L2. The second angle θ2 is an angle formed by the second line segment L2 and the third line segment L3. The third angle θ3 is an angle formed by the third line segment L3 and the fourth line segment L4. The fourth angle θ4 is an angle formed by the fourth line segment L4 and the first line segment L1. The first to fourth angles θ1 to θ4 are equal to each other, and are 90 degrees. In other words, the centers C1 to 4 of the first to fourth dummy wafers D1 to D4 are arranged on the same circumference at equal intervals.

In this case, the areas of the first to fourth hatched areas A1 to A4 can be made uniform. Further, the inventors have made intensive studies and have found that these first to fourth shadow areas A1 to A4 can cover the entire shadow area a. In other words, when the first to fourth dry cleaning is performed, the entire shadow area a is exposed, and the deposit adhering to the shadow area a can be removed.

(Modification of the first embodiment)

In the first embodiment described above, the first to fourth dry cleaning may be performed continuously after the plasma treatment is performed on a batch of product wafers W. Fig. 10 is an explanatory diagram showing a series of flows of wafer processing according to this modification example using a wafer.

(Step S21)

In step S21, plasma processing is continuously performed on a batch of, for example, 25 product wafers W. This step S21 is the same as step S11.

(Steps S22 to S25)

In step S22, a first dry cleaning is performed using the first dummy wafer D1. In step S23, a second dry cleaning is performed using the second dummy wafer D2. In step S24, a third dry cleaning is performed using the third dummy wafer D3. In step S25, a fourth dry cleaning is performed using the fourth dummy wafer D4. These steps S22 to S25 are continuously performed, and are the same as steps S12, S14, S16, and S18, respectively.

After step S25, steps S21 to S25 are repeated, for example. As shown in fig. 11, the step S21 may be performed a plurality of times, that is, the steps S22 to S25 may be performed after the plasma treatment is performed on the plurality of batches of product wafers W.

In this modification, the same effects as those of the first embodiment can be obtained. That is, by performing the first to fourth dry cleaning, the deposits adhering to the first to fourth shadow areas A1 to A4 can be removed.

(Modification of the first embodiment)

In the first embodiment described above, after the fifth dry cleaning different from the first to fourth dry cleaning is performed, the first to fourth dry cleaning may be performed during the plasma processing of the one batch of product wafers W. Fig. 12 is an explanatory diagram showing a series of flows of wafer processing according to this modification example using a wafer.

(Step S30)

In step S30, plasma processing is continuously performed on a batch of, for example, 25 product wafers W. This step S30 is the same as step S11.

(Step S31)

In step S31, a fifth dry cleaning is performed using the fifth dummy wafer D5. Specifically, first, a fifth dummy wafer D5 is disposed above the electrostatic chuck 13. At this time, the fifth dummy wafer D5 is arranged such that the center of the fifth dummy wafer D5 is at the same position as the center of the electrostatic chuck 13 in a plan view. The position of the fifth dummy wafer D5 is the fifth position in the present invention.

Next, the fifth dummy wafer D5 is placed on the electrostatic chuck 13, and is then held by suction by the electrostatic chuck 13. The subsequent dry cleaning method is the same as the first dry cleaning of step S12. That is, the deposition inside the chamber 10 is removed using plasma (including radicals and ions) obtained by exciting the dry cleaning gas. Thus, the fifth dry cleaning is performed.

(Step S32)

In step S32, plasma processing is continuously performed on a batch of, for example, 25 product wafers W. This step S32 is the same as step S11.

(Step S33)

In step S33, a first dry cleaning is performed using the first dummy wafer D1. This step S33 is the same as step S12.

(Step S34)

In step S34, plasma processing is continuously performed on a batch of, for example, 25 product wafers W. This step S34 is the same as step S11.

(Step S35)

In step S35, a second dry cleaning is performed using the second dummy wafer D2. This step S35 is the same as step S14.

(Step S36)

In step S36, plasma processing is continuously performed on a batch of, for example, 25 product wafers W. This step S36 is the same as step S11.

(Step S37)

In step S37, a third dry cleaning is performed using the third dummy wafer D3. This step S37 is the same as step S16.

(Step S38)

In step S38, plasma processing is continuously performed on a batch of, for example, 25 product wafers W. This step S38 is the same as step S11.

(Step S39)

In step S39, a fourth dry cleaning is performed using the fourth dummy wafer D4. This step S39 is the same as step S18.

After step S39, steps S30 to S39 are repeated, for example.

In step S31 of the present modification, the fifth dry cleaning is performed using the fifth dummy wafer D5, but the so-called waferless dry cleaning may be performed instead.

(Modification of the first embodiment)

In the first embodiment described above, the first to fourth dry cleaning may be performed continuously after the fifth dry cleaning different from the first to fourth dry cleaning is performed and the plasma treatment is further performed on the one batch of product wafers W. Fig. 13 is an explanatory diagram showing a series of flows of wafer processing according to this modification example using a wafer.

(Step S41)

In step S41, plasma processing is continuously performed on a batch of, for example, 25 product wafers W. This step S41 is the same as step S11.

(Step S42)

In step S42, a fifth dry cleaning is performed using the fifth dummy wafer D5. This step S42 is the same as step S31.

(Step S43)

In step S43, plasma processing is continuously performed on a batch of, for example, 25 product wafers W. This step S43 is the same as step S11.

(Steps S44 to S47)

In step S44, a first dry cleaning is performed using the first dummy wafer D1. In step S45, a second dry cleaning is performed using the second dummy wafer D2. In step S46, a third dry cleaning is performed using the third dummy wafer D3. In step S47, a fourth dry cleaning is performed using the fourth dummy wafer D4. These steps S44 to S47 are continuously performed, and are the same as steps S12, S14, S16, and S18, respectively.

After step S47, steps S41 to S47 are repeated, for example.

Steps S42 and S43 may be performed a plurality of times, that is, steps S44 to S47 may be performed after plasma processing is performed on a plurality of batches of product wafers W. In this case, when steps S42 and S43 are performed a plurality of times, deposits of the shadow area a which cannot be removed in step S42 accumulate. Therefore, by performing the first to fourth dry cleaning in steps S43 to S47, the deposit in the shadow area a can be removed.

In step S42 of the present modification, the fifth dry cleaning is performed using the fifth dummy wafer D5, but instead, so-called waferless dry cleaning may be performed.

(Modification of the first embodiment)

In the first embodiment and the modification thereof described above, the first to fourth dry cleaning is performed in a state where the first to fourth dummy wafers D1 to D4 are placed on the electrostatic chuck 13, but may be performed in a state spaced apart from the electrostatic chuck 13. The first dry cleaning using the first dummy wafer D1 will be described below, but the other second to fourth dry cleaning are similar.

For example, as shown in fig. 14 (a), in the edge ring 14, the first ring portion 110 may be smaller in the radial direction. In this case, even if the first dummy wafer D1 is placed at the first position for the first dry cleaning, the distance F1 between the one end D1b and the outer peripheral end of the center portion 100 of the electrostatic chuck 13 cannot be sufficiently ensured, and the one end D1a is located above the edge ring 14. That is, the shadow area A1 on the one end D1a side of the edge ring 14 overlaps the first dummy wafer D1 in a plan view, and is not completely exposed.

Accordingly, as shown in fig. 14 (b), the first dry cleaning may be performed in a state where the first dummy wafer D1 is supported by the lifter 20 and spaced apart from the electrostatic chuck 13. In this case, the distance F2 (margin) between the one end D1b of the first dummy wafer D1 and the outer peripheral end of the center portion 100 of the electrostatic chuck 13 can be sufficiently ensured, and the one end D1a is located between the inner peripheral end of the edge ring 14 and the outer peripheral end of the center portion 100 of the electrostatic chuck 13. Then, in the edge ring 14, the shadow area A1 on the one end D1a side is exposed without overlapping the first dummy wafer D1, and the deposit adhering to the shadow area A1 in the first dry cleaning can be removed. In the present modification, as described above, the inner peripheral portion of the surface 111a of the first ring portion 110 in the edge ring 14 is inclined toward the surface 110 a.

The inventors have made intensive studies and have found that the distance H between the back surface D1c of the first dummy wafer D1 shown in fig. 14 (b) and the surface of the electrostatic chuck 13 is preferably 2mm or less. That is, when the distance H is 2mm or less, the plasma state is not changed during the first dry cleaning, and the cleaning effect similar to that in the state where the first dummy wafer D1 is placed on the electrostatic chuck 13 can be obtained.

In the same manner, the second to fourth dry cleaning is performed in a state where the second to fourth dummy wafers D2 to D4 are supported by the lifter 20 and spaced apart from the electrostatic chuck 13. Then, the shadow areas A2 to A4 are exposed, and the deposits adhering to the shadow areas A2 to A4 can be removed in the second to fourth dry cleaning, respectively.

In the first embodiment and the modification thereof described above, the first to fourth dry cleaning is performed to expose the shadow areas A1 to A4 and remove the deposits, but the number of dry cleaning is not limited thereto. The number of dry cleaning is at least 2. For example, in the case of performing the dry cleaning twice, the first dry cleaning and the third dry cleaning described above may be performed.

In the first embodiment and the modification example, the number of the product wafers W subjected to the plasma treatment is 25, but the present invention is not limited thereto. For example, a batch may be plural of 2 or more, or may be one batch.

< Dry cleaning method of the second embodiment >

The dry cleaning method of the second embodiment will be described. In the second embodiment, a description will be given of plasma processing for the product wafer W and dry cleaning using the small-diameter dummy wafer Ds.

Further, as described above, the small-diameter dummy wafer Ds used in the dry cleaning of the second embodiment is a wafer having a smaller diameter than the product wafer W. Fig. 15 is a longitudinal sectional view showing a schematic structure of the small-diameter dummy wafer Ds, the electrostatic chuck 13, and the edge ring 14. Fig. 16 is a plan view showing a schematic structure of the small-diameter dummy wafer Ds, the electrostatic chuck 13, and the edge ring 14.

As shown in fig. 15 and 16, the diameter of the small diameter dummy wafer Ds is the same as the inner diameter of the edge ring 14. In this case, the shadow region a is exposed so as not to overlap the small-diameter dummy wafer Ds in a plan view. The diameter of the small-diameter dummy wafer Ds is not limited to the illustrated example.

(Step T11)

In step T11, a batch of, for example, 25 product wafers W are continuously subjected to plasma treatment. This step T11 is the same as step S11.

(Step T12)

In step T12, dry cleaning is performed using the small-diameter dummy wafer Ds. Specifically, first, a small-diameter dummy wafer Ds is placed above the electrostatic chuck 13. At this time, the small-diameter dummy wafer Ds is arranged such that the center of the small-diameter dummy wafer Ds is positioned at the same position as the center of the electrostatic chuck 13 in a plan view. The position of the small-diameter dummy wafer Ds is a cleaning position in the present invention. In this case, the shadow area a of the edge ring 14 is not overlapped with the small-diameter dummy wafer Ds in a plan view and is exposed.

Next, the small-diameter dummy wafer Ds is placed on the electrostatic chuck 13, and is then sucked and held by the electrostatic chuck 13. Thereafter, a backside gas is supplied to the back surface of the small-diameter dummy wafer Ds, and dry cleaning is performed. The dry cleaning method is the same as the first dry cleaning of step S12. That is, the deposition inside the chamber 10 is removed using plasma (including radicals and ions) obtained by exciting the dry cleaning gas. At this time, the deposit adhering to the shadow region a exposed from the small-diameter dummy wafer Ds is also removed. Thus, dry cleaning is performed.

Further, after step T11, steps T11 and T12 are repeated, for example. As shown in fig. 18, step T11 may be performed a plurality of times, that is, step T12 may be performed after plasma processing is performed on a plurality of batches of product wafers W.

As described above, in the second embodiment, by dry cleaning using the small-diameter dummy wafer Ds, the deposit adhering to the shadow area a can be removed. That is, as shown in fig. 4, the deposit can be properly removed even in the shadow area a where the deposit cannot be removed by the shadow of the dummy wafer D in the past. In the second embodiment, the portions other than the shadow area a are exposed on the surfaces 110a and 111a of the edge ring 14, and the deposits adhering to the portions can be removed appropriately. Accordingly, the deposits can be removed on the entire surfaces 110a and 111a of the edge ring 14, so that the occurrence of particles can be suppressed, the yield of products can be improved, and the operation time of the plasma processing apparatus 1 can be prolonged.

The inventors of the present invention have conducted intensive studies and have confirmed that deposits can be properly removed from the diameter phia of the small-diameter dummy wafer Ds on the outer peripheral side of the radius ratio (phia/2 to 0.4) mm, and that the dry cleaning effect can be obtained. Here, the small-diameter dummy wafer Ds has an inner portion (flat portion) with flat upper and lower surfaces, and an outer portion (beveled portion) formed on the outer peripheral side of the inner portion and having chamfered upper and lower surfaces. In the small-diameter dummy wafer Ds, the annular range of 0.4mm in the radial direction coincides with the bevel portion (chamfer portion). Therefore, it is estimated that even under the small-diameter dummy wafer Ds, the cleaning effect can be obtained under the inclined surface portion.

The lower limit of the diameter phia of the small diameter dummy wafer Ds is preferably such that the incidence of radicals and ions does not affect the extent of the central portion 100 of the electrostatic chuck 13, i.e., { (outer diameter of the central portion 100 of the electrostatic chuck 13)/2 } + (phia/2-bevel length) =diameter phib/2 of the flat portion. The upper limit of the diameter phia of the small-diameter dummy wafer Ds may be smaller than the diameter of the product wafer W. That is, the diameter Φa of the small-diameter dummy wafer Ds is preferably within the range of the following formula (1).

{ (Outer diameter of center portion 100 of electrostatic chuck 13)/2 }. Ltoreq { (diameter of small diameter dummy wafer Ds. Phi.A)/2- (bevel length) } = diameter of flat portion. Phi.B/2 < { (diameter of product wafer W)/2 } … … (1)

Further, the present inventors have made intensive studies and have confirmed that, as shown in fig. 14 (b), when dry cleaning is performed in a state in which the small-diameter dummy wafer Ds is supported by the lifter 20 and spaced apart from the electrostatic chuck 13, a dry cleaning effect can be obtained on the inner peripheral side than the bevel portion. That is, in this case, a dry cleaning effect (where X is longer than the bevel length of 0.4 mm) can be obtained at the outer peripheral side of the radius ratio (φA/2-X) mm. In this way, it is assumed that the main reason why the range of obtaining the dry cleaning effect is increased as compared with the case where the small-diameter dummy wafer Ds is not pushed up is that the range in which radicals and ions can be incident is increased when the small-diameter dummy wafer Ds is pushed up. Therefore, dry cleaning (hereinafter referred to as "lift cleaning") may be performed in a state where the small-diameter dummy wafer Ds is lifted. In this case, in order to reduce damage to the electrostatic chuck 13, the dry cleaning (hereinafter referred to as "mounting cleaning") may be performed under conditions different from those under which the small-diameter dummy wafer Ds is mounted on the electrostatic chuck 13. Specifically, in the lift cleaning, the first high-frequency electric power may be lower than the first high-frequency electric power in the placement cleaning. The second high-frequency electric power may be lower than the mounting cleaning in the lift cleaning (or the second high-frequency electric power may not be supplied). In the lift cleaning, the pressure in the chamber 10 may be set to be higher than the loading cleaning.

The cleaning may be carried out by pushing up the cleaning device and the cleaning device. That is, the lift cleaning may be performed before (or after) the mounting cleaning. This can remove deposits (for example, deposits adhering to the gap between the electrostatic chuck 13 and the edge ring 14, and deposits adhering to the outer peripheral mounting surface of the electrostatic chuck 13) that cannot be removed completely in dry cleaning performed with the small-diameter dummy wafer Ds mounted on the electrostatic chuck 13. In the case of carrying out the lift cleaning and the mount cleaning under different conditions (i.e., in the case of carrying out the lift cleaning at low power), it is preferable to carry out the lift cleaning after carrying out the mount cleaning.

In step T12, the back side gas is supplied to the back surface of the small-diameter dummy wafer Ds for dry cleaning, but the back side gas may not be supplied. By not supplying the backside gas, the small-diameter dummy wafer Ds is heated by the plasma, and the deposition removed by the dry cleaning can be suppressed from adhering to the small-diameter dummy wafer Ds. This can reduce the frequency of cleaning the small-diameter dummy wafer Ds. In this case, the cooling of the small-diameter dummy wafer Ds may be performed by supplying the backside gas during or after the dry cleaning in order to send out the small-diameter dummy wafer Ds.

In the case of performing the lift cleaning, the small-diameter dummy wafer Ds is spaced from the electrostatic chuck 13, and thus the supply of the backside gas is stopped. In this case, the small-diameter dummy wafer Ds may be cooled in order to send out the small-diameter dummy wafer Ds. That is, the small-diameter dummy wafer Ds may be placed on the electrostatic chuck 13 after the lift cleaning, and the small-diameter dummy wafer Ds may be cooled by supplying a backside gas to the back surface of the small-diameter dummy wafer Ds after the suction and holding by the electrostatic chuck 13.

(Modification of the second embodiment)

In the second embodiment described above, the dry cleaning using the small-diameter dummy wafers Ds may be performed after the normal dry cleaning is performed and the plasma treatment is further performed on a batch of product wafers W. Fig. 19 is an explanatory diagram showing a series of flows of wafer processing according to this modification example using a wafer.

(Step T21)

In step T21, a batch of, for example, 25 product wafers W are continuously subjected to plasma treatment. This step T21 is the same as step S11.

(Step T22)

In step T22, a fifth dry cleaning (normal dry cleaning) is performed using the fifth dummy wafer D5. This step T22 is the same as step S31.

(Step T23)

In step T23, a batch of, for example, 25 product wafers W are continuously subjected to plasma treatment. This step T23 is the same as step S11.

(Step T24)

In step T24, dry cleaning is performed using the small-diameter dummy wafer Ds. This step T24 is identical to step T12.

Further, after step T24, steps T23 and T24 are repeated, for example.

In this modification, the same effects as those of the second embodiment can be obtained. That is, by dry cleaning using the small-diameter dummy wafer Ds, the deposit adhering to the shadow area a can be removed.

In addition, the steps T24 may be performed after the steps T22 and T23 are performed a plurality of times, that is, after the plasma treatment is performed on the product wafers W of a plurality of batches. In this case, when steps T22 and T23 are performed a plurality of times, deposits of the shadow area a which cannot be removed in step T22 accumulate. Therefore, by dry cleaning using the small-diameter dummy wafer Ds in step T24, the deposit in the shadow area a can be removed.

In step T22 of the present modification, the fifth dry cleaning is performed using the fifth dummy wafer D5, but instead, so-called waferless dry cleaning may be performed.

< Additional notes >

[ Additional notes 1]

A method of cleaning a plasma processing apparatus, comprising:

A step of disposing a first dummy substrate in a first position relative to a mounting table in the chamber, and performing a first dry cleaning of the chamber; and

A step of disposing a second dummy substrate in a second position with respect to the mounting table in the chamber, and performing a second dry cleaning of the chamber,

The center of the first position and the center of the second position are respectively different positions from the center of the carrying table in a plan view,

The first position and the second position are different positions in a plan view.

[ Additional notes 2]

The method for cleaning a plasma processing apparatus according to item 1, wherein,

At least the first dry cleaning or the second dry cleaning is performed in a state where the first dummy substrate or the second dummy substrate is mounted on the mounting table.

[ Additional notes 3]

At least the first dry cleaning or the second dry cleaning is performed in a state where the first dummy substrate or the second dummy substrate is supported by a lifter and spaced apart from the mounting table.

[ Additional notes 4]

The method for cleaning a plasma processing apparatus according to item 3, wherein,

At least in the first dry cleaning or the second dry cleaning, a distance between a rear surface of the first dummy substrate or a rear surface of the second dummy substrate and a surface of the mounting table is 2mm or less.

[ Additional notes 5]

The method for cleaning a plasma processing apparatus according to any one of the additional items 1 to 4, wherein,

The mounting table includes:

An electrostatic chuck for holding the first dummy substrate or the second dummy substrate; and

An edge ring disposed so as to surround the first dummy substrate or the second dummy substrate mounted on the electrostatic chuck,

At least in the first dry cleaning or the second dry cleaning, one end of the first dummy substrate or the second dummy substrate is located between an inner peripheral end of the edge ring and an outer peripheral end of the electrostatic chuck in a plan view, and the other end is located outside the inner peripheral end of the edge ring.

[ Additional notes 6]

The method for cleaning a plasma processing apparatus according to any one of the additional notes 1 to 5, wherein,

The first simulation substrate and the second simulation substrate are the same simulation substrate.

[ Additional notes 7]

The first simulation substrate and the second simulation substrate are different simulation substrates.

[ Additional notes 8]

The method for cleaning a plasma processing apparatus according to any one of the additional items 1 to 7, wherein,

Between the first dry cleaning and the second dry cleaning, plasma processing is performed on the product substrate,

The plasma treatment is performed in a state in which the product substrate is placed on the placement stage so that the center of the product substrate and the center of the placement stage are positioned at the same position in a plan view.

[ Additional notes 9]

The method for cleaning a plasma processing apparatus according to item 8, wherein,

And performing the plasma treatment a plurality of times between the first dry cleaning and the second dry cleaning.

[ Additional notes 10]

The method for cleaning a plasma processing apparatus according to any one of the additional items 1 to 7,

Wherein,

The first dry cleaning and the second dry cleaning are continuously performed.

[ Additional notes 11]

The method for cleaning a plasma processing apparatus according to any one of the additional notes 1 to 10, wherein,

At least the first dry cleaning or the second dry cleaning is performed in a state in which high-frequency electric power is supplied to the mounting table.

[ Additional notes 12]

The method for cleaning a plasma processing apparatus according to any one of items 1 to 11, wherein,

The method also comprises the following steps: a third dummy substrate is disposed in a third position with respect to the mounting table in the chamber, and a third dry cleaning is performed in the chamber, wherein a center of the third position is a position different from a center of the mounting table in a plan view,

The third position is a position different from the first position and the second position in a plan view.

[ Additional notes 13]

The method for cleaning a plasma processing apparatus according to item 12, wherein,

The method also comprises the following steps: a fourth dummy substrate is disposed in a fourth position with respect to the mounting table in the chamber, and a fourth dry cleaning is performed in the chamber,

The center of the fourth position is a position different from the center of the mounting table in a plan view,

The fourth position is a position different from the first position, the second position, and the third position in a plan view.

[ Additional notes 14]

The method for cleaning a plasma processing apparatus according to item 13, wherein,

The first angle, the second angle, the third angle and the fourth angle are respectively equal,

The first angle is an angle formed by a first line segment connecting the center of the mounting table and the center of the first position and a second line segment connecting the center of the mounting table and the center of the second position,

The second angle is an angle formed by the second line segment and a third line segment connecting the center of the mounting table and the center of the third position,

The third angle is an angle formed by the third line segment and a fourth line segment connecting the center of the mounting table and the center of the fourth position,

The fourth angle is an angle formed by the fourth line segment and the first line segment.

[ Additional notes 15]

The method for cleaning a plasma processing apparatus according to any one of supplementary notes 13 to 14, further comprising:

a step of disposing a fifth dummy substrate in a fifth position with respect to the mounting table in the chamber, and performing a fifth dry cleaning in the chamber; and

A step of performing plasma treatment on the product substrate after the fifth dry cleaning described above,

The center of the fifth position is the same position as the center of the mounting table in a plan view,

The plasma treatment is performed in a state in which the product substrate is placed on the placement stage so that the center of the product substrate and the center of the placement stage are at the same position in a plan view,

The first dry cleaning, the second dry cleaning, the third dry cleaning, and the fourth dry cleaning are performed after the plasma treatment is performed, respectively.

[ Additional notes 16]

After the plasma treatment, the first dry cleaning, the second dry cleaning, the third dry cleaning, and the fourth dry cleaning are continuously performed.

[ Additional notes 17]

A plasma processing apparatus, comprising:

A chamber;

A mounting table provided in the chamber and configured to mount the first dummy substrate or the second dummy substrate;

a dry cleaning part for dry cleaning the interior of the chamber; and

A control part for controlling the dry cleaning part,

The control unit controls the dry cleaning unit to execute:

A step of disposing a first dummy substrate in a first position with respect to the mounting table in the chamber, and performing a first dry cleaning in the chamber; and

A step of disposing a second dummy substrate in a second position with respect to the mounting table in the chamber, and performing a second dry cleaning in the chamber,

[ Additional notes 18]

A method of cleaning a plasma processing apparatus, comprising:

A step of placing a product substrate in a processing position with respect to a placement table in the chamber, and performing plasma processing on the product substrate; and

A step of disposing a dummy substrate having a smaller diameter than the product substrate in a cleaning position with respect to the mounting table in the chamber, and dry-cleaning the chamber,

The center of the processing position and the center of the cleaning position are the same positions as the center of the mounting table in a plan view.

The plasma processing apparatus 1 of the above embodiment is a capacitively-coupled plasma processing apparatus, but the plasma processing apparatus to which the present invention is applied is not limited thereto. For example, the plasma processing apparatus may be an inductively coupled plasma processing apparatus.

The presently disclosed embodiments are considered in all respects to be illustrative and not restrictive. The above-described embodiments may be omitted, replaced, and modified in various ways without departing from the scope and gist of the present invention.

Description of the reference numerals

1 Plasma processing apparatus

10 Chamber

11 Carrying table

12. Lower electrode

31. Second high-frequency power supply

50. Gas supply source group

70. Control unit

D1 First simulation wafer

D2 second dummy wafer.

Claims

1. A method of cleaning a plasma processing apparatus, comprising:

a step (a) of carrying a product substrate on a carrying table provided in a chamber, and performing plasma treatment on the product substrate; and

And (b) placing a first dummy substrate having a smaller diameter than the product substrate on the stage, generating plasma in the chamber, and performing a first dry cleaning for cleaning the stage.

2. The method of cleaning a plasma processing apparatus according to claim 1, wherein:

after performing said step (a) a plurality of times, performing said step (b).

3. The method of cleaning a plasma processing apparatus according to claim 1, wherein:

And (c) placing a second dummy substrate having a diameter equal to the diameter of the product substrate on the stage, and generating plasma in the chamber to perform a second dry cleaning of cleaning the stage.

4. A method for cleaning a plasma processing apparatus according to claim 3, comprising:

a first flow, wherein the step (c) is performed after the step (a) is performed for a plurality of times; and

A second flow, after the step (a) is carried out for a plurality of times, the step (b) is carried out,

And after the first flow is performed for a plurality of times, performing the second flow.

5. The method of cleaning a plasma processing apparatus according to claim 1, wherein:

And (d) generating plasma in the chamber without placing the dummy substrate on the stage, and performing a second dry cleaning.

6. The method of cleaning a plasma processing apparatus according to claim 5, comprising:

a first flow, wherein the step (d) is performed after the step (a) is performed for a plurality of times; and

7. The method for cleaning a plasma processing apparatus according to any one of claims 1 to 6, wherein:

And (e) generating plasma in the chamber while the first dummy substrate is spaced apart from the mounting table, and performing a third dry cleaning for cleaning the mounting table.

8. The method of cleaning a plasma processing apparatus according to claim 7, wherein:

after performing said step (b), performing said step (e).

9. The method of cleaning a plasma processing apparatus according to claim 7, wherein:

The plasma processing apparatus has a first power supply that generates a plasma,

The electric power supplied from the first power supply in the third dry cleaning is lower than the electric power supplied from the first power supply in the first dry cleaning.

10. The method of cleaning a plasma processing apparatus according to claim 7, wherein:

The plasma processing apparatus has a second power supply for supplying bias electric power to the stage,

The electric power supplied from the second power supply in the third dry cleaning is lower than the electric power supplied from the second power supply in the first dry cleaning.

11. The method of cleaning a plasma processing apparatus according to claim 7, wherein:

The bias electric power is supplied from the second power supply in the first dry cleaning, and the bias electric power is not supplied from the second power supply in the third dry cleaning.

12. The method for cleaning a plasma processing apparatus according to any one of claims 1 to 6, wherein:

The stage includes an electrostatic chuck holding the product substrate,

The diameter of the first dummy substrate is greater than or equal to the diameter of the portion of the electrostatic chuck on which the product substrate is placed and held, and less than the diameter of the product substrate.

13. The method of cleaning a plasma processing apparatus according to claim 12, wherein:

the first dummy substrate has an inner portion having flat upper and lower surfaces, and an outer portion formed on an outer peripheral side of the inner portion and having chamfered upper and lower surfaces,

The diameter of the inner portion is greater than the diameter of the portion of the electrostatic chuck on which the product substrate is placed and held and less than the diameter of the product substrate.

14. The method of cleaning a plasma processing apparatus according to claim 13, wherein:

The diameter of the inner portion is equal to the diameter of the portion of the electrostatic chuck on which the product substrate is placed and held.

15. A method of cleaning a plasma processing apparatus, comprising:

And (b) generating plasma in the chamber while a first dummy substrate having a smaller diameter than the product substrate is spaced apart from the stage, thereby performing a first dry cleaning of cleaning the stage.

16. A method of cleaning a plasma processing apparatus, comprising: