Cleaning method and plasma treatment device

Abstract

The present invention provides a cleaning method and a plasma processing device for suppressing damage to a stage and removing deposits deposited on the periphery of the stage. The cleaning method is a cleaning method for a stage in a plasma processing device, including a separation process and a removal process. In the separation process, a lifting mechanism is used to separate the stage from the substrate. In the removal process, after the separation process, plasma is generated by supplying high-frequency power to the stage from a high-frequency power supply, thereby removing the deposits deposited on the stage. In addition, in the separation process, the separation distance between the stage and the substrate is set so that the synthetic impedance formed around the periphery of the stage is lower than the synthetic impedance formed directly above the center of the stage.

Description

[0001] This application is a divisional application of an application with a filing date of November 20, 2020, application number 202011307540.6, and invention name “Cleaning method and plasma treatment device”. Technical Field

[0002] Embodiments of the present disclosure relate to a method for cleaning a stage in a plasma processing apparatus and the plasma processing apparatus. Background Art

[0003] Conventionally, there is known a technique for removing deposits deposited on a mounting table on which a substrate such as a semiconductor wafer is mounted using plasma in a plasma processing apparatus.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2011-054825

[0007] Patent Document 2: Japanese Patent Application Laid-Open No. 7-78802 Summary of the invention

[0008] Problem that the invention aims to solve

[0009] The present disclosure provides a technology capable of removing deposits deposited on the outer periphery of a mounting table while suppressing damage to the mounting table.

[0010] Solutions for solving problems

[0011] A cleaning method according to one embodiment of the present invention is a cleaning method for a stage in a plasma processing device, wherein the plasma processing device comprises: a stage on which a substrate is placed; a lifting mechanism for lifting the substrate relative to the stage; and a high-frequency power supply connected to the stage. A cleaning method according to one embodiment of the present invention comprises a separation process and a removal process. In the separation process, a lifting mechanism is used to separate the stage from the substrate. In the removal process, after the separation process, plasma is generated by supplying high-frequency power from the high-frequency power supply to the stage, thereby removing the deposits deposited on the stage. In addition, in the separation process, the separation distance between the stage and the substrate is set so that the synthetic impedance formed around the outer periphery of the stage is lower than the synthetic impedance formed directly above the center of the stage.

[0012] Another cleaning method disclosed herein is a method for cleaning a stage in a plasma processing device, wherein the plasma processing device comprises: a processing container; a substrate stage disposed in the processing container; and a substrate lifting mechanism having lifting pins for supporting the substrate, wherein the cleaning method comprises the following steps: step (a), controlling the substrate lifting mechanism to raise the lifting pins to receive a dummy substrate piece moved into the processing container; step (b), controlling the substrate lifting mechanism to position the front end of the lifting pins above the stage and at a position lower than the position at which the dummy substrate piece is received; step (c), after step (b), using plasma to clean the inside of the processing container; and step (d), controlling the substrate lifting mechanism to raise the lifting pins to move the dummy substrate piece out of the processing container.

[0013] Another embodiment of the plasma processing device disclosed herein comprises: a processing container; a substrate mounting table disposed in the processing container; a substrate lifting mechanism having lifting pins for supporting the substrate; and a control unit, wherein the control unit is configured to perform the following processes: process (a), controlling the substrate lifting mechanism to raise the lifting pins to receive a dummy substrate transferred into the processing container; process (b), controlling the substrate lifting mechanism to position the front end of the lifting pins above the mounting table and lower than the position at which the dummy substrate is received; process (c), after process (b), cleaning the inside of the processing container using plasma; and process (d), controlling the substrate lifting mechanism to raise the lifting pins to transfer the dummy substrate out of the processing container.

[0014] Effects of the Invention

[0015] According to the present disclosure, it is possible to remove deposits deposited on the outer peripheral portion of the mounting table while suppressing damage to the mounting table. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic cross-sectional view showing the structure of a plasma processing apparatus according to one embodiment.

[0017] Figure 2 This is a flowchart showing an example of the cleaning process.

[0018] Figure 3 This is a diagram showing an example of distribution of plasma generated when high-frequency power is supplied while a wafer is mounted on a mounting table.

[0019] Figure 4 This is a diagram showing an example of distribution of plasma generated when high-frequency power is supplied in a state where the wafer is separated from the mounting table.

[0020] Figure 5 This is a graph showing the relationship between the separation distance between the wafer and the mounting surface and the etching rate of the resist film at each position on the upper surface of the wafer.

[0021] Figure 6 This is a graph showing the relationship between the separation distance between the wafer and the mounting surface and the etching rate of the resist film at each position on the lower surface of the wafer.

[0022] Figure 7 This is a graph showing the relationship between the separation distance between the wafer and the mounting surface and the etching rate of the resist film at each position of the focus ring.

[0023] Description of Reference Numerals

[0024] P: plasma; W: wafer; 1: processing container; 2: mounting table; 6: electrostatic chuck; 6a: mounting surface; 10: plasma processing device; 10a: first RF power supply; 16: shower head; 61: lifting pin; 62: lifting mechanism; 100: control unit. DETAILED DESCRIPTION

[0025] Hereinafter, the cleaning method of the mounting table in the plasma processing device and the embodiment of the plasma processing device disclosed in the present application will be described with reference to the accompanying drawings. In addition, the present disclosure is not limited by this embodiment. Each embodiment can be appropriately combined within the scope that does not cause the processing content to conflict.

[0026] In the past, a plasma processing device for performing plasma processing on a substrate such as a semiconductor wafer is known. Such a plasma processing device has a mounting table for mounting the substrate in a processing container that can form a vacuum space, for example. Lifting pins are housed inside the mounting table, and the plasma processing device uses the lifting pins to transfer the substrate.

[0027] In a plasma processing device, due to plasma processing, a deposit including reaction products such as CF-based polymers is deposited on the mounting surface of the mounting table. Since the deposit is deposited on the mounting surface, abnormalities such as poor adsorption of the substrate may sometimes occur. Therefore, in the plasma processing device, dry cleaning is performed to remove the deposits deposited on the mounting surface by plasma processing.

[0028] Here, for example, when the diameter of the mounting surface is smaller than the diameter of the wafer, sometimes the reaction product of the processing gas used in the plasma processing enters between the outer periphery of the mounting table and the back side of the wafer, so that the deposit is locally deposited on the outer periphery of the mounting table. In addition, a structure such as a focusing ring is arranged around the outer periphery of the mounting table. Therefore, the outer periphery of the mounting table is less likely to be exposed to the plasma than the center. Therefore, the deposit is likely to remain on the outer periphery of the mounting table after dry cleaning.

[0029] Thus, the outer peripheral portion of the mounting table tends to be more likely to have sediment deposited than the central portion of the mounting table.

[0030] In order to remove the deposits deposited on the outer periphery of the mounting table, for example, it is conceivable to extend the time of dry cleaning. However, if the time of dry cleaning is extended, the damage to the mounting table becomes greater, and sometimes the life of the mounting table may be shortened.

[0031] Therefore, it is desired to remove the deposits deposited on the mounting table while suppressing damage to the mounting table.

[0032] [Structure of plasma processing apparatus]

[0033] Figure 1 1 is a schematic cross-sectional view showing the structure of a plasma processing device 10 according to an embodiment. The plasma processing device 10 has a processing container 1, which is airtightly configured and electrically grounded. The processing container 1 is cylindrical and is, for example, made of aluminum. The processing container 1 divides a processing space for generating plasma. A mounting table 2 is provided in the processing container 1 to horizontally support a semiconductor wafer (hereinafter referred to as "wafer") W serving as a substrate (work-piece). The mounting table 2 is configured to include a susceptor (base) 2a and an electrostatic chuck (ESC: Electrostatic chuck) 6. The susceptor 2a is made of a conductive metal, such as aluminum, and has a function as a lower electrode. The electrostatic chuck 6 has a function for electrostatically adsorbing the wafer W. The electrostatic chuck 6 is arranged on the upper surface of the susceptor 2a. The mounting table 2 is supported by a support table 4. The support table 4 is supported by a support member 3, such as quartz.

[0034] A focus ring 5 made of, for example, single crystal silicon is provided on the outer periphery above the stage 2. Specifically, the focus ring 5 is formed in a ring shape and is arranged on the upper surface of the susceptor 2a so as to surround the outer periphery of the placement surface (the upper surface of the electrostatic chuck 6) on the stage 2. Furthermore, a cylindrical inner wall member 3a made of, for example, quartz is provided in the processing container 1 so as to surround the circumference of the stage 2 and the support table 4.

[0035] The susceptor 2a is connected to the first RF power supply 10a via the first matching device 11a, and is connected to the second RF power supply 10b via the second matching device 11b. The first RF power supply 10a is used to generate plasma, and is configured to supply a high-frequency power of a predetermined frequency from the first RF power supply 10a to the susceptor 2a of the stage 2. In addition, the second RF power supply 10b is used to attract ions (for bias), and is configured to supply a high-frequency power of a predetermined frequency lower than the first RF power supply 10a from the second RF power supply 10b to the susceptor 2a of the stage 2. In this way, the stage 2 is configured to be able to apply a voltage. On the other hand, above the stage 2, a shower head 16 having a function as an upper electrode is provided in a manner parallel to the stage 2. The shower head 16 and the stage 2 function as a pair of electrodes (upper electrode and lower electrode).

[0036] The electrostatic chuck 6 is formed in a disk shape with a flat upper surface, and the upper surface is set as a mounting surface 6e for mounting the wafer W. The electrostatic chuck 6 is configured such that an electrode 6a is sandwiched between the insulators 6b, and the electrode 6a is connected to the DC power supply 12. Moreover, the DC power supply 12 applies a DC voltage to the electrode 6a, so that the wafer W is adsorbed by the Coulomb force.

[0037] In addition, in the present embodiment, the diameter of the mounting surface 6 e is set to be slightly smaller than the diameter of the wafer W as an example.

[0038] A temperature adjustment medium flow path 2d is formed inside the mounting table 2, and the temperature adjustment medium flow path 2d is connected to the inlet piping 2b and the outlet piping 2c. Moreover, the mounting table 2 is configured to be controlled to a specified temperature by circulating an appropriate temperature adjustment medium, such as cooling water, in the temperature adjustment medium flow path 2d. In addition, a gas supply pipe 30 for supplying a cold heat transfer gas (back side gas) such as helium to the back side of the wafer W is provided in a manner penetrating the mounting table 2, etc., and the gas supply pipe 30 is connected to a gas supply source not shown. Through these structures, the wafer W adsorbed and held on the upper surface of the mounting table 2 by the electrostatic chuck 6 is controlled to a specified temperature.

[0039] The mounting table 2 is provided with a plurality of, for example, three, pin through holes 200 (in Figure 1Only one is shown in the figure. ), lift pins 61 are respectively arranged inside these pin through holes 200. The lift pins 61 are connected to the lift mechanism 62. The lift mechanism 62 lifts and lowers the lift pins 61 so that the lift pins 61 can freely protrude and sink relative to the loading surface 6e of the loading table 2. When the lift pins 61 are raised, the front ends of the lift pins 61 protrude from the loading surface 6e of the loading table 2, and the wafer W is held above the loading surface 6e of the loading table 2. On the other hand, when the lift pins 61 are lowered, the front ends of the lift pins 61 are accommodated in the pin through holes 200, and the wafer W is loaded on the loading surface 6e of the loading table 2. In this way, the lift mechanism 62 lifts and lowers the wafer W relative to the loading surface 6e of the loading table 2 through the lift pins 61. In addition, the lifting mechanism 62 holds the wafer W above the mounting surface 6 e of the mounting table 2 via the lifting pins 61 in a state where the lifting pins 61 are lifted.

[0040] The shower head 16 is provided on the top wall of the processing container 1. The shower head 16 includes a main body 16a and an upper top plate 16b constituting an electrode plate, and is supported on the upper part of the processing container 1 via an insulating member 95. The main body 16a is made of a conductive material, such as aluminum with an anodized surface, and is configured so that the upper top plate 16b can be detachably supported on the lower part of the main body 16a.

[0041] A gas diffusion chamber 16c is provided inside the main body 16a. In addition, a large number of gas flow holes 16d are formed at the bottom of the main body 16a so as to be located at the lower part of the gas diffusion chamber 16c. In addition, a gas introduction hole 16e is provided in the upper top plate 16b so as to overlap with the above-mentioned gas flow hole 16d and penetrate the upper top plate 16b in the thickness direction. With such a structure, the processing gas supplied to the gas diffusion chamber 16c is dispersedly supplied to the processing container 1 in a spraying manner through the gas flow hole 16d and the gas introduction hole 16e.

[0042] A gas inlet port 16g for introducing a processing gas into the gas diffusion chamber 16c is formed in the main body 16a. The gas inlet port 16g is connected to one end of a gas supply pipe 15a. The other end of the gas supply pipe 15a is connected to a gas supply source (gas supply unit) 15 for supplying a processing gas. In the gas supply pipe 15a, a mass flow controller (MFC) 15b and an opening and closing valve V2 are sequentially arranged from the upstream side. A processing gas for plasma etching is supplied from the gas supply source 15 to the gas diffusion chamber 16c via the gas supply pipe 15a. The processing gas is supplied to the processing container 1 in a dispersed manner in a spray shape via the gas flow hole 16d and the gas inlet hole 16e.

[0043] The shower head 16 as the upper electrode is electrically connected to the variable DC power supply 72 via a low pass filter (LPF) 71. The variable DC power supply 72 is configured to be able to turn on / off the power supply by an on / off switch 73. The current / voltage of the variable DC power supply 72 and the on / off of the on / off switch 73 are controlled by the control unit 100 described later. In addition, as described later, when a high frequency is applied from the first RF power supply 10a and the second RF power supply 10b to the mounting table 2 to generate plasma in the processing space, the on / off switch 73 is turned on by the control unit 100 as needed. Thus, a predetermined DC voltage is applied to the shower head 16 as the upper electrode.

[0044] A cylindrical ground conductor 1a is provided so as to extend from the side wall of the processing container 1 to a position above the height position of the shower head 16. The cylindrical ground conductor 1a has a ceiling wall at its upper portion.

[0045] An exhaust port 81 is formed at the bottom of the processing container 1. The exhaust port 81 is connected to a first exhaust device 83 via an exhaust pipe 82. The first exhaust device 83 has a vacuum pump, and is configured to reduce the pressure in the processing container 1 to a predetermined vacuum level by operating the vacuum pump. On the other hand, a wafer W loading / unloading port 84 is provided on the side wall of the processing container 1, and a gate valve 85 for opening and closing the loading / unloading port 84 is provided at the loading / unloading port 84.

[0046] A sediment shield 86 is provided along the inner wall surface on the inner side of the processing container 1. The sediment shield 86 is used to prevent etching byproducts (sediments) from adhering to the processing container 1. A conductive member (GND block) 89 connected in a manner that can control the potential relative to the ground is provided at a height position substantially the same as that of the wafer W of the sediment shield 86, thereby preventing abnormal discharge. In addition, a sediment shield 87 extending along the inner wall member 3a is provided at the lower end of the sediment shield 86. The sediment shields 86 and 87 are provided to be detachable.

[0047] The operation of the plasma processing apparatus 10 having the above configuration is centrally controlled by the control unit 100. The control unit 100 includes a process controller 101 having a CPU and controlling each unit of the plasma processing apparatus 10, a user interface 102, and a storage unit 103.

[0048] The user interface 102 includes a keyboard for a process manager to input commands for managing the plasma processing apparatus 10 , a display for visually displaying the operating status of the plasma processing apparatus 10 , and the like.

[0049] The storage unit 103 stores a recipe, which stores a control program (software), processing condition data, etc., for realizing various processes performed by the plasma processing apparatus 10 under the control of the process controller 101. Then, any recipe is called out from the storage unit 103 according to instructions from the user interface 102 as needed, and the process controller 101 is caused to execute the recipe, thereby performing a desired process using the plasma processing apparatus 10 under the control of the process controller 101. In addition, regarding the recipes such as the control program and the processing condition data, the recipes in a state stored in a computer storage medium (such as a hard disk, a CD, a floppy disk, a semiconductor memory, etc.) that can be read by a computer can be used. In addition, the recipes such as the control program and the processing condition data can also be transmitted from other devices via, for example, a dedicated line at any time and used online.

[0050] [Cleaning]

[0051] Next, refer to Figure 2 The contents of the cleaning process performed by the plasma processing apparatus 10 according to the embodiment will be described. Figure 2 This is a flowchart showing an example of the cleaning process. Figure 2 The cleaning process described as an example is mainly achieved by operating the plasma processing apparatus 10 according to the control of the control unit 100 .

[0052] The wafer W used in the cleaning process may be a product wafer or a dummy wafer.

[0053] First, the wafer W is moved into the processing container 1 (S100). In step S100, the gate valve 85 is opened, and the wafer W is moved into the processing container 1 by the transfer arm (not shown), and is placed on the mounting surface 6e of the mounting table 2. Specifically, in step S100, the lift pins 61 are in a raised state, and the wafer W is transferred from the transfer arm to the lift pins 61. Then, the lift pins 61 are lowered to transfer the wafer W from the lift pins 61 to the mounting surface 6e. Then, the gate valve 85 is closed.

[0054] Next, the wafer W is separated from the mounting surface 6e by raising the lift pins 61 (pin raising) (S101). The information of the separation distance between the wafer W and the mounting surface 6e is stored in advance in the storage unit 103, for example, and the control unit 100 raises the lift pins 61 according to the information stored in the storage unit 103.

[0055] Here, an example is shown in which, after the wafer W is temporarily placed on the mounting surface 6e in step S101, the wafer W is raised to the set separation distance in step S101. This example is not limited to this example, and for example, after the wafer W is received by the lift pins 61 in step S101, the lift pins 61 are lowered to arrange the wafer W at a height position where the separation distance between the wafer W and the mounting surface 6e becomes a preset distance. The separation distance between the wafer W and the mounting surface 6e in step S101 is at least smaller than the distance between the height position where the lift pins 61 receive the wafer W and the mounting surface 6e in step S100.

[0056] Next, after the processing container 1 is depressurized to a predetermined vacuum degree by the first exhaust device 83, a reaction gas is supplied from the gas supply source 15 to the processing container 1 via the gas supply pipe 15a (S102). In the present embodiment, when the deposit to be cleaned is a CF-based polymer, the reaction gas supplied from the gas supply source 15 is O2 gas. In addition, the reaction gas is not limited to O2 gas, and may also be other oxygen-containing gases such as CO gas, CO2 gas, and O3 gas. In addition, when the deposit contains silicon and metal in addition to the CF-based polymer, a halogen-containing gas, for example, may also be added to the reaction gas O2 gas. The halogen-containing gas is, for example, a fluorine-based gas such as CF4 gas and NF3 gas. In addition, the halogen-containing gas may also be a chlorine-based gas such as Cl2 gas, or a bromine-based gas such as HBr gas. In this way, an oxygen-containing gas is used as a reaction gas in the cleaning process.

[0057] Next, high-frequency power is supplied to the mounting table 2 as the lower electrode (S103). In step S103, the control unit 100 controls the first RF power supply 10a and the second RF power supply 10b to generate high-frequency power, thereby supplying the high-frequency power to the base 2a of the mounting table 2. In addition, the control unit 100 applies the DC power supplied from the variable DC power supply 72 to the shower head 16 by turning on the on-off switch 73. As a result, a plasma of an oxygen-containing gas is generated in the processing container 1. In addition, the frequency of the high-frequency power generated by the first RF power supply 10a and the second RF power supply 10b is not particularly limited. In addition, an example in which the plasma processing device 10 includes the first RF power supply 10a and the second RF power supply 10b is shown here, but the plasma processing device 10 does not necessarily need to include the second RF power supply 10b.

[0058] Next, the control unit 100 determines whether a preset processing time has passed since the high-frequency power supply was started in step S103 (S104). If the preset processing time has not passed (S104: No), the process of step S104 is executed again.

[0059] On the other hand, when the set processing time has elapsed (S104: Yes), the supply of high frequency power to the mounting table 2 is stopped (S105). In addition, the supply of the reaction gas into the processing container 1 is stopped (S106).

[0060] Then, after the reaction gas in the processing container 1 is exhausted, the gate valve 85 is opened, and the wafer W is moved out of the processing container 1 by the transfer arm (not shown) (S107). Specifically, the control unit 100 raises the lifting pins 61 to place the wafer W at the transfer position, and transfers the wafer W supported by the lifting pins 61 to the transfer arm. At this point, the cleaning method shown in this flowchart ends.

[0061] [About plasma generated during cleaning process]

[0062] Figure 3 2 is a diagram showing an example of the distribution of plasma generated when high frequency power is supplied while the wafer W is mounted on the mounting table 2. Figure 4 1 is a diagram showing an example of distribution of plasma generated when high-frequency power is supplied in a state where the wafer W is separated from the mounting table 2 .

[0063] like Figure 3 As shown, when high frequency power is supplied from the first RF power supply 10 a to the mounting table 2 while the wafer W is mounted on the mounting table 2 , the plasma P is uniformly distributed in the in-plane direction of the wafer W in the decompression space between the wafer W and the shower head 16 .

[0064] In contrast, the inventors of the present application have found that: Figure 4 As shown, by separating the wafer W from the mounting surface 6 e and appropriately setting the separation distance, the plasma P can be locally present around the outer peripheral portion of the mounting table 2 .

[0065] For example, the mechanism can be described as follows. That is, when the wafer W is separated from the mounting surface 6e, a decompression space is also formed between the wafer W and the mounting surface 6e. The decompression space can be regarded as a capacitor provided on the path of the high-frequency power from the first RF power source 10a to the ground connected to the shower head 16 via the mounting table 2. The capacitor becomes a part of the synthetic impedance on the path of the high-frequency power from the first RF power source 10a to the ground.

[0066] Here, it is considered that the path of the high frequency power from the mounting table 2 to the shower head 16 is divided into a path just above the center of the mounting table 2 and a path just above the outer periphery of the mounting table 2 (hereinafter referred to as "the path of the center" and "the path of the outer periphery"). Figure 3As shown in FIG. 1 , when the wafer W is placed on the mounting table 2, the synthetic impedance per unit area of ​​the mounting surface 6e is substantially the same in the path at the center and the path at the periphery. Figure 4 As shown, when the wafer W is separated from the mounting surface 6e, the path in the outer peripheral portion becomes a parallel path of a path passing through the wafer W and a path outside the wafer W that does not pass through the wafer W. The path passing through the wafer W is a path passing through a capacitor of a decompression space formed between the wafer W and the mounting surface 6e, and the path not passing through the wafer W is a path not passing through the above-mentioned capacitor.

[0067] Therefore, the combined impedance per unit area formed by the two parallel high-frequency power paths around the outer periphery of the placement surface 6e is lower than the combined impedance per unit area formed just above the center of the placement surface 6e.

[0068] The high frequency power flows intensively around the outer periphery of the mounting surface 6e where the synthetic impedance is relatively low. As a result, the density of the plasma P around the outer periphery of the mounting surface 6e is higher than the density of the plasma P in the center of the mounting surface 6e, and a ring-shaped plasma P is formed around the outer periphery of the mounting surface 6e.

[0069] In the cleaning process according to the embodiment, by using the plasma P that is locally present around the outer periphery of the stage 2, the deposits deposited on the outer periphery of the stage 2 can be efficiently removed. That is, according to the cleaning process according to the embodiment, by concentrating the plasma P around the outer periphery of the stage 2, the removal force of the deposits deposited on the outer periphery of the stage 2 can be improved. Therefore, the deposits deposited on the outer periphery of the stage 2 can be reliably removed in a short time. In addition, in the portion other than the outer periphery, the density of the plasma P is relatively reduced, so that the portion other than the outer periphery of the stage 2 can be prevented from being damaged by the plasma P.

[0070] As described above, according to the cleaning process according to the embodiment, it is possible to remove deposits deposited on the outer peripheral portion of the mounting table 2 while suppressing damage to the mounting table 2 .

[0071] Furthermore, according to the cleaning process according to the embodiment, it is possible to efficiently remove deposits deposited on the outer periphery of the mounting table 2 without preparing an electrode of a special structure for generating local plasma on the outer periphery of the mounting table.

[0072] In addition, among the deposits deposited on the outer periphery of the mounting table 2, the deposits of CF-based polymers can be removed by the plasma of oxygen-containing gases such as O2 gas. In addition, the deposits of Si-based or metal-based materials can be removed by the plasma of halogen-containing gases such as CF4 gas, NF3 gas, Cl2 gas, HBr gas, etc. In addition, the mixed deposits of CF-based polymers and at least one of Si-based and metal-based materials can be removed by the plasma of a mixed gas of oxygen-containing gas and halogen-containing gas. In addition, the deposits of CF-based polymers can also be removed by hydrogen-containing gases such as H2 gas, and nitrogen-containing gases such as N2. In addition, rare gases such as argon and helium can also be added.

[0073] The inventors of the present application conducted the following experiment: when a wafer W coated with a resist film as an organic film similar to the CF-based polymer deposit was treated with O2 gas plasma, the etching rate of the resist film at various positions on the surface of the wafer W was investigated instead of the CF-based polymer deposit. Figure 5 The experimental results are shown in . Figure 5 Graph showing the relationship between the separation distance between the wafer W and the mounting surface 6 e and the etching rate of the resist film at each position on the upper surface of the wafer W. FIG.

[0074] In addition, the inventors of the present application conducted the same experiment as described above, with the surface of the wafer W coated with the anti-etching film facing the mounting table 6e. That is, the following experiment was conducted to investigate the etching rate of the anti-etching film at various positions on the lower surface (the surface coated with the anti-etching film) of the wafer W when the wafer W was processed by O2 gas plasma. Figure 6 The experimental results are shown in . Figure 6 Graph showing the relationship between the separation distance between the wafer W and the mounting surface 6 e and the etching rate of the resist film at each position on the lower surface of the wafer W. FIG.

[0075] Figure 5 and Figure 6 The processing conditions for the experimental results shown are as follows.

[0076] Pressure in processing container 1: 100~800mT

[0077] High frequency power: ~1000W

[0078] Gas type and flow rate: O2 gas

[0079] Diameter of wafer W: 300mm

[0080] Processing time: 30 seconds

[0081] in addition, Figure 5 and Figure 6In the example of FIG. 1 , the position at which the etching rate is measured is indicated by the distance from the center of the wafer W. For example, the center of the wafer W is 0 mm.

[0082] like Figure 5 As shown in the figure, when the separation distance is less than 2.3 mm, the etching rate at the center of the wafer W, that is, 0 mm (indicated by a quadrilateral mark in the figure) and 100 mm (indicated by a circular mark in the figure) closer to the center increases. According to this result, it can be seen that when the separation distance is less than 2.3 mm, the plasma diffuses to the vicinity of the center of the upper surface of the wafer W.

[0083] In addition, if Figure 6 As shown in the figure, when the separation distance is less than 2.3 mm, the outer periphery of the wafer W, that is, 148 mm (indicated by a diamond mark in the figure) and 145 mm (indicated by an inverted triangle mark in the figure) closer to the outer periphery are hardly etched. The mounting surface 6e of the mounting table 2 is roughly the same as (slightly smaller than) the diameter of the wafer W. Therefore, according to this result, it can be seen that when the separation distance is less than 2.3 mm, plasma is hardly generated between the wafer W and the mounting surface 6e.

[0084] On the other hand, Figure 6 As shown in FIG. 1 , when the separation distance is greater than 5 mm, the etching rate increases near the center of the wafer W, that is, at 0 mm and 100 mm. From this result, it can be seen that when the separation distance is greater than 5 mm, the plasma diffuses to the vicinity of the center of the lower surface of the wafer W, in other words, the vicinity of the center of the mounting surface 6 e.

[0085] According to the above results, the separation distance between the wafer W and the mounting surface 6e is preferably 2.3 mm or more and 5 mm or less. By setting the separation distance within this range, the plasma can be appropriately localized around the outer periphery of the mounting table 2. That is, the center of the mounting table 2 can be protected from the influence of the plasma, and a ring-shaped plasma can be generated around the outer periphery of the mounting table 2.

[0086] In addition, if Figure 6 As shown in FIG. 1 , the etching rate near the periphery of the wafer W, i.e., at 148 mm and 145 mm, is the highest when the separation distance is 3 mm. Based on this result, the separation distance between the wafer W and the mounting surface 6e is preferably 2.3 mm to 3.5 mm, and more preferably 2.3 mm to 3 mm. By setting the separation distance within this range, the deposits deposited on the periphery of the mounting table 2 can be reliably removed in a short time.

[0087] As described above, the separation distance between the wafer W and the mounting surface 6 e is set to be small in this embodiment. The separation distance between the wafer W and the mounting surface 6 e is at least smaller than the thickness of the plasma sheath generated between the wafer W and the shower head 16 during the cleaning process.

[0088] In order to investigate the state of plasma outside the wafer W, the inventors of the present application conducted the following experiment: a chip-shaped wafer W coated with a resist film was attached to the focus ring 5, and the etching rate of the resist film at various positions on the upper surface of the chip-shaped wafer W was investigated. Figure 7 The experimental results are shown in . Figure 7 Graph 1 is a graph showing the relationship between the separation distance between the wafer W and the mounting surface 6 e and the etching rate of the resist film at each position of the focus ring 5 . Figure 7 The experimental results shown are based on the treatment conditions and Figure 5 and Figure 6 The experimental results shown are the same.

[0089] exist Figure 7 In the graph shown, the horizontal axis represents the focus ring position. The focus ring position is the position on the focus ring 5 where the etching rate is measured, and is represented by the distance from the inner edge of the upper surface of the focus ring 5. For example, the inner edge of the upper surface of the focus ring 5 closest to the mounting surface 6e of the mounting table 2 is 0 mm. Figure 7 In the graph shown in FIG. 1 , the horizontal axis represents the distance from the mounting surface 6e, and the horizontal axis represents the distance from the mounting surface 6e. Figure 7 In the middle, mark until 15mm.

[0090] In addition, Figure 7 In the graph shown, the vertical axis represents the etching rate of the resist film on the focus ring 5. Specifically, the etching rate of a predetermined material placed on the upper surface of the focus ring 5 is represented as the etching rate of the focus ring.

[0091] like Figure 7 As shown in the figure, when the separation distance between the wafer W and the mounting surface 6e is 0 mm (indicated by a triangular mark in the figure) and 1 mm (indicated by a quadrilateral mark in the figure) which is less than 2.3 mm, the etching rate of the resist film on the focus ring 5 is low. In contrast, when the separation distance is 2.5 mm (indicated by a circular mark in the figure) which is greater than 2.3 mm, the etching rate of the resist film on the focus ring 5 increases compared to the etching rates at 0 mm and 1 mm, and a high value is shown in the inner peripheral portion close to the mounting table 2.

[0092] From this result, it can be seen that by setting the separation distance between wafer W and mounting surface 6e to be greater than 2.3 mm, plasma with high plasma density is generated around the outer periphery of mounting surface 6e, specifically in a region including the outer periphery of mounting surface 6e and the inner periphery of the upper surface of focus ring 5.

[0093] Furthermore, the etching rate of the resist film on the focus ring 5 when the separation distance is 2.5 mm is highest at the inner peripheral portion of the focus ring 5 close to the stage 2 , and decreases as it moves away from the stage 2 .

[0094] From this result, it can be seen that the density of plasma generated in the cleaning process is higher in the inner peripheral portion of the focus ring 5 than in the outer peripheral portion of the focus ring 5. That is, by setting the separation distance to be greater than 2.3 mm, plasma can be generated in a local area around the outer peripheral portion of the mounting surface 6e, specifically, including the outer peripheral portion of the mounting surface 6e and the inner peripheral portion of the upper surface of the focus ring 5 and excluding the outer peripheral portion of the upper surface of the focus ring 5.

[0095] [Modifications]

[0096] In the above-mentioned cleaning process, the plasma processing apparatus 10 may clean other structures other than the mounting table 2 including the inner wall of the processing container 1 .

[0097] For example, the plasma processing apparatus 10 may generate plasma in the processing container 1 with the wafer W mounted on the mounting surface 6 e , thereby removing deposits deposited on the inner wall of the processing container 1 using the generated plasma.

[0098] This process can be performed, for example, after the wafer W is loaded into the processing container 1 and placed on the mounting surface 6e in step S100 and before the lifting pins 61 are raised in step S101. In this case, it is preferable to stop supplying high-frequency power and reaction gas to extinguish the plasma before the lifting pins 61 are raised in step S101. The reason is that if the lifting pins 61 are raised in a state where plasma is generated, an annular plasma may not be properly formed around the outer peripheral portion of the mounting table 2.

[0099] Alternatively, for example, the process may be performed after the set process time has elapsed in step S104. In this case, the lift pins 61 are lowered after the set process time has elapsed in step S104 to place the wafer W on the placement surface 6e, and the plasma process may be continued in this state.

[0100] In this way, by performing the cleaning process with the wafer W mounted on the mounting table 2 , it is possible to protect the mounting surface 6 e using the wafer W and remove deposits deposited on the inner wall of the processing container 1 .

[0101] Alternatively, the plasma processing apparatus 10 may perform a process in which plasma is generated in the processing container 1 without accommodating the wafer W in the processing container 1 , thereby removing deposits deposited in the processing container 1 using the generated plasma.

[0102] This treatment may be performed, for example, before the wafer W is carried into the processing container 1 in step S100. In this case, it is also preferable to stop supplying high frequency power and reaction gas to extinguish the plasma before the wafer W is carried into the processing container 1 in step S100. In addition, this treatment may be performed after the wafer W is carried out of the processing container 1 in step S107.

[0103] In this way, by performing the cleaning process in a state where no wafer W is accommodated in the processing container 1, the deposits deposited on the outer periphery of the mounting surface 6e can be removed emphatically, and the deposits deposited on the portions other than the outer periphery of the mounting surface 6e can also be removed. That is, the entire mounting surface 6e can be cleaned.

[0104] As described above, the cleaning method involved in the present embodiment is a cleaning method for a stage in a plasma processing device (as an example, a plasma processing device 10), wherein the plasma processing device includes: a stage (as an example, the stage 2) on which a substrate (as an example, a wafer W) is placed; a lifting mechanism (as an example, the lifting mechanism 62) which lifts and lowers the substrate relative to the stage; and a high-frequency power supply (as an example, the first RF power supply 10a) connected to the stage. The cleaning method involved in the present embodiment includes a separation process and a removal process. In the separation process, the lifting mechanism is used to separate the stage from the substrate. In the removal process, after the separation process, plasma is generated by supplying high-frequency power from the high-frequency power supply to the stage, thereby removing the deposits deposited on the stage. In addition, in the separation process, the separation distance between the stage and the substrate is set so that the synthetic impedance formed around the outer peripheral portion of the stage is lower than the synthetic impedance formed just above the center portion of the stage.

[0105] According to the cleaning method according to the present embodiment, the plasma can be locally present around the outer peripheral portion of the mounting table, so that it is possible to remove deposits deposited on the outer peripheral portion of the mounting table while suppressing damage to the mounting table.

[0106] The separation distance between the stage and the substrate is smaller than the thickness of the sheath of plasma generated in the removal process (for example, plasma generated between the wafer W and the shower head 16). That is, in the cleaning method according to the present embodiment, the separation distance between the stage and the substrate is small.

[0107] Specifically, the separation distance between the stage and the substrate is 2.3 mm or more and 5 mm or less. By setting the separation distance within this range, the plasma can be appropriately localized around the outer periphery of the stage. That is, the center of the stage can be protected from the influence of the plasma, and an annular plasma can be generated around the outer periphery of the stage.

[0108] The separation distance between the mounting table and the substrate is preferably 2.3 mm to 3.5 mm, more preferably 2.3 mm to 3 mm. By setting the separation distance within this range, the deposits deposited on the outer periphery of the mounting table 2 can be reliably removed in a short time.

[0109] The density of the plasma generated in the removal process is higher around the outer periphery of the substrate than at the center of the substrate. Therefore, it is possible to remove the deposits deposited on the outer periphery of the stage while suppressing damage to the stage.

[0110] The plasma processing apparatus includes a ring member (for example, a focusing ring 5) surrounding the outer periphery of the mounting surface of the mounting table. In addition, regarding the density of the plasma generated in the removal process, the density of the inner periphery of the ring member is higher than that of the outer periphery of the ring member. That is, according to the cleaning method involved in this embodiment, an annular plasma can be formed around the outer periphery of the mounting table, specifically, in a local area including the outer periphery of the mounting table and the inner periphery of the ring member and excluding the outer periphery of the ring member.

[0111] In the removal step, plasma of an oxygen-containing gas (for example, O 2 gas or a reaction gas in which a halogen gas is added to O 2 gas) is generated. This allows the carbon-based deposits deposited on the outer periphery of the mounting table to be appropriately removed.

[0112] The plasma processing apparatus includes a processing container (for example, the processing container 1) for accommodating a mounting table. In addition, the cleaning method according to the embodiment includes a step of removing deposits deposited on the processing container using plasma while the substrate is mounted on the mounting table before the separation step (for example, before step S101) or after the removal step (for example, after step S104). Thus, the mounting table can be protected by the substrate, and attachments deposited on the inner wall of the processing container can be removed.

[0113] The plasma processing apparatus includes a processing container (for example, the processing container 1) for accommodating a stage. In addition, the cleaning method according to the embodiment includes a step of removing deposits deposited in the processing container using plasma in a state where no substrate is accommodated in the processing container before the separation step (for example, before step S100) or after the removal step (for example, after step S107). Thus, the entire mounting surface of the stage can be cleaned.

[0114] It should be understood that the embodiments disclosed herein are illustrative in all respects and are not restrictive. In fact, the above embodiments can be implemented in a variety of ways. In addition, the above embodiments can be omitted, replaced, and changed in various ways without departing from the attached claims and their gist.

Claims

1. A cleaning method, which is a cleaning method in a plasma processing device, The plasma processing device comprises: Handling containers; a substrate mounting table disposed in the processing container; and The substrate lifting mechanism includes lifting pins for supporting the substrate. The cleaning method comprises the following steps: Step (a), controlling the substrate lifting mechanism to raise the lifting pins to receive the dummy substrate carried into the processing container; Step (b), controlling the substrate lifting mechanism so that the front end of the lifting pin is located above the substrate mounting table and at a position lower than the position where the dummy substrate is received in step (a); Step (c), after step (b), cleaning the inside of the processing container using plasma; and In step (d), the substrate lifting mechanism is controlled to raise the lifting pins so as to carry the dummy substrate out of the processing container.

2. The cleaning method according to claim 1, wherein: The step (b) is performed after the step (a).

3. The cleaning method according to claim 1 or 2, wherein: The step (d) is performed after the step (c).

4. The cleaning method according to claim 1 or 2, wherein: After the step (d), a step of cleaning the inside of the processing container using plasma is performed in a state where the substrate and the dummy substrate are not accommodated in the processing container.

5. The cleaning method according to claim 1 or 2, wherein: The cleaning method includes step (e), after step (a), lowering the lifting pins to place the substrate dummy on the substrate mounting table, The step (b) is performed after the step (e), wherein the lifting pins are raised to position the dummy substrate sheet at a position lower than a position at which the dummy substrate sheet is received in the step (a).

6. The cleaning method according to claim 5, wherein: The cleaning method includes step (f) of cleaning the inside of the processing container using plasma while the dummy substrate is placed on the mounting surface of the substrate mounting table after step (e) and before step (b).

7. The cleaning method according to claim 1 or 2, wherein: The cleaning method includes a step (g) of lowering the lift pins to place the substrate dummy on the substrate mounting table after the step (c) and before the step (d).

8. The cleaning method according to claim 7, wherein: The cleaning method includes a step (h) of cleaning the inside of the processing container using plasma after the step (g) and before the step (d) while the dummy substrate is placed on the mounting surface of the substrate mounting table.

9. The cleaning method according to claim 1 or 2, wherein: In the step (c), a ring-shaped plasma is generated around the outer periphery of the substrate mounting table.

10. The cleaning method according to claim 1 or 2, wherein: The separation distance between the mounting surface of the substrate mounting table and the surface of the dummy substrate sheet facing the mounting surface is smaller than the thickness of the plasma sheath generated in the step (c).

11. The cleaning method according to claim 1 or 2, wherein: A separation distance between a mounting surface of the substrate mounting table and a surface of the dummy substrate sheet facing the mounting surface is greater than or equal to 2.3 mm and less than or equal to 5 mm.

12. The cleaning method according to claim 11, wherein: A separation distance between a mounting surface of the substrate mounting table and a surface of the dummy substrate sheet facing the mounting surface is greater than or equal to 2.3 mm and less than or equal to 3.5 mm.

13. The cleaning method according to claim 11, wherein: A separation distance between a mounting surface of the substrate mounting table and a surface of the dummy substrate sheet facing the mounting surface is greater than or equal to 2.3 mm and less than or equal to 3 mm.

14. The cleaning method according to claim 1 or 2, wherein: Regarding the density of the plasma generated in the step (c), the density around the outer peripheral portion of the substrate is higher than the density at the center portion of the dummy substrate sheet.

15. The cleaning method according to claim 14, wherein: The plasma processing apparatus includes a ring member surrounding the outer periphery of the mounting surface of the substrate mounting table. Regarding the density of the plasma generated in the step (c), the density at the inner peripheral portion of the ring member is higher than the density at the outer peripheral portion of the ring member.

16. The cleaning method according to claim 1 or 2, wherein: In the step (c), plasma of an oxygen-containing gas is generated.

17. The cleaning method according to claim 1 or 2, wherein: In the step (c), high frequency power for generating plasma is supplied to the substrate mounting table.

18. The cleaning method according to claim 1 or 2, wherein: In the step (c), high frequency power for attracting ions is supplied to the substrate mounting table.

19. The cleaning method according to claim 1, wherein: A cleaning process is performed while a wafer (W) is placed on a mounting table (2).

20. The cleaning method according to claim 1 or 19, wherein: A cleaning process is performed in a state where no wafer (W) is contained in a processing container (1).

21. A plasma processing device comprising: Handling containers; A substrate mounting table, which is disposed in the processing container; a substrate lifting mechanism including lifting pins for supporting the substrate; and Control Department, in, The control unit is configured to execute the following processing: Process (a), controlling the substrate lifting mechanism to raise the lifting pins to receive the substrate dummy sheet carried into the processing container; Process (b), controlling the substrate lifting mechanism so that the front end of the lifting pin is located above the substrate mounting table and lower than the position where the substrate dummy sheet is received in process (a); Process (c), after the process (b), cleaning the inside of the process container using plasma; and In process (d), the substrate lifting mechanism is controlled to raise the lifting pins so as to carry the dummy substrate out of the processing container.

22. The plasma processing apparatus according to claim 21, wherein: The control unit is configured to perform the process (b) after the process (a).

23. The plasma processing apparatus according to claim 21 or 22, wherein: The control unit is configured to perform the process (d) after the process (c).

24. The plasma processing apparatus according to claim 21 or 22, wherein: The control unit is configured to perform, after the process (d), a process of cleaning the inside of the process container using plasma in a state where the substrate and the dummy substrate are not accommodated in the process container.

25. The plasma processing apparatus according to claim 21 or 22, wherein: The control unit is configured to perform processing (e), and after processing (a), the control unit is configured to lower the lifting pins to place the substrate dummy piece on the substrate mounting table, and after processing (e), the control unit is configured to raise the lifting pins in processing (b) to place the substrate dummy piece at a position lower than the position at which the substrate dummy piece was received in processing (a).

26. The plasma processing apparatus according to claim 25, wherein: The control unit is configured to execute process (f) to clean the inside of the processing container using plasma in a state where the dummy substrate is placed on the mounting surface of the substrate mounting table after process (e) and before process (b).

27. The plasma processing apparatus according to claim 21 or 22, wherein: The control unit is configured to execute the process (g) by lowering the lift pins to place the dummy substrate on the substrate mounting table after the process (c) and before the process (d).

28. The plasma processing apparatus according to claim 27, wherein: The control unit is configured to execute process (h), and after process (g) and before process (d), clean the inside of the processing container using plasma in a state where the dummy substrate is placed on the mounting surface of the substrate mounting table.

29. The plasma processing apparatus according to claim 21 or 22, wherein: In the process (c), a ring-shaped plasma is generated around the outer periphery of the substrate mounting table.

30. The plasma processing apparatus according to claim 21 or 22, wherein: The thickness of the sheath of the plasma generated in the process (c) is smaller than that of the processing of the mounting surface of the substrate mounting table and the surface of the dummy substrate sheet facing the mounting surface.

31. The plasma processing apparatus according to claim 21 or 22, wherein: A separation distance between a mounting surface of the substrate mounting table and a surface of the dummy substrate sheet facing the mounting surface is greater than or equal to 2.3 mm and less than or equal to 5 mm.

32. The plasma processing apparatus according to claim 31, wherein: A separation distance between a mounting surface of the substrate mounting table and a surface of the dummy substrate sheet facing the mounting surface is greater than or equal to 2.3 mm and less than or equal to 3.5 mm.

33. The plasma processing apparatus according to claim 31, wherein: A separation distance between a mounting surface of the substrate mounting table and a surface of the dummy substrate sheet facing the mounting surface is greater than or equal to 2.3 mm and less than or equal to 3 mm.

34. The plasma processing apparatus according to claim 21 or 22, wherein: Regarding the density of the plasma generated in the process (c), the density around the outer peripheral portion of the substrate is higher than the density at the center portion of the dummy substrate.

35. The plasma processing apparatus according to claim 34, wherein: A ring member surrounding the outer periphery of the mounting surface of the substrate mounting table is provided, Regarding the density of the plasma generated in the process (c), the density at the inner peripheral portion of the ring member is higher than the density at the outer peripheral portion of the ring member.

36. The plasma processing apparatus according to claim 21 or 22, wherein: The control unit is configured to generate plasma of an oxygen-containing gas in the process (c).

37. The plasma processing apparatus according to claim 21 or 22, wherein: The plasma processing apparatus is configured to supply high frequency power for generating plasma to the substrate mounting table in the process (c).

38. The plasma processing apparatus according to claim 21 or 22, wherein: The control unit is configured to supply high-frequency power for attracting ions to the substrate mounting table in the process (c).

39. The plasma processing apparatus according to claim 21, wherein: A cleaning process is performed while a wafer (W) is placed on a mounting table (2).

40. The plasma processing apparatus according to claim 21 or 39, wherein: A cleaning process is performed in a state where no wafer (W) is contained in a processing container (1).

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