JP2023157446A - Plasma processing method, plasma processing device, and stage - Google Patents

Abstract

To provide a technique capable of suppressing the generation of aluminum fluoride due to a reaction between a fluorine-containing gas and a stage containing aluminum during a plasma process by the fluorine-containing gas.SOLUTION: A plasma processing method on a plasma processing device having a processing container, a stage that is configured with a material containing aluminum for placing a substrate in the processing container, a plasma source for generating plasma in the processing container, and a Y2O3 portion formed in a portion on which the plasma in the processing container acts, includes the steps for generating a plasma of a fluorine-containing gas in the processing container, generating YF3 gas by a reaction between the plasma of fluorine-containing gas and the Y2O3 portion, and depositing YF3 on the surface of the stage to form a protective film mainly composed of YF3.SELECTED DRAWING: Figure 5

Description

The present disclosure relates to a plasma processing method, a plasma processing apparatus, and a stage.

Patent Document 1 discloses a microwave introduction module that is placed on the ceiling of a processing container and introduces microwaves into the processing container to generate plasma from gas, and a microwave introduction module that is arranged on the ceiling of the processing container and that introduces microwaves into the processing container to generate plasma from gas. A microwave plasma apparatus is described that has a plurality of gas supply holes for introducing gas into a plasma space, and performs plasma processing on a wafer placed in a processing container. It is also described that an insulating material such as yttria (Y ₂ O ₃ ) is thermally sprayed onto the inner surface of the ceiling of a processing container (chamber) so that surface waves can easily pass through. Further, a stage containing aluminum is described.

Japanese Patent Application Publication No. 2018-195548

The present disclosure provides a technique that can suppress the generation of aluminum fluoride due to a reaction between a fluorine-containing gas and a stage containing aluminum during plasma processing using a fluorine-containing gas.

A plasma processing method according to one aspect of the present disclosure includes a processing container, a stage made of a material containing aluminum on which a substrate is placed within the processing container, and a plasma source that generates plasma in the processing container. , a plasma processing method in a plasma processing apparatus having a Y ₂ O ₃ portion formed in a portion of the inner wall of the processing container where the plasma acts, the method comprising: generating plasma of a fluorine-containing gas in the processing container; , generating YF ₃ gas by a reaction between the plasma of the fluorine-containing gas and the Y ₂ O ₃ portion, and depositing YF ₃ on the stage surface to form a protective film mainly composed of YF ₃ . and has.

According to the present disclosure, a technique is provided that can suppress the generation of aluminum fluoride due to a reaction between a fluorine-containing gas and a stage containing aluminum during plasma processing using a fluorine-containing gas.

1 is a cross-sectional view showing an example of a plasma processing apparatus capable of implementing a plasma processing method according to an embodiment. 2 is a cross-sectional view showing the AA cross section of the plasma processing apparatus in FIG. 1. FIG. FIG. 3 is a schematic diagram for explaining the state inside the processing container after a film forming process. FIG. 3 is a schematic diagram for explaining damage to a stage in a cleaning process. FIG. 3 is a diagram for explaining a plasma processing method for forming a protective film on a stage surface. FIG. ₃ is a diagram showing a vapor pressure curve of YF 3 in comparison with that of AlF ₃ . This is a photograph confirming that a film was formed on a sample chip made of Al ₂ O ₃ in an experimental example. FIG. 3 is a diagram showing the composition of a film formed on a sample chip. It is a figure _which shows another example of _Y2O3 part. It is a figure which shows yet another example of _{a Y2O3} part.

Embodiments will be specifically described below with reference to the accompanying drawings.

FIG. 1 is a cross-sectional view showing an example of a plasma processing apparatus capable of implementing a plasma processing method according to an embodiment, and FIG. 2 is a cross-sectional view showing an AA cross section of the plasma processing apparatus in FIG.

The plasma processing apparatus 100 is a microwave plasma processing apparatus that performs plasma processing using microwave plasma, and is configured as a PECVD (Plasma Enhanced Chemical Vapor Deposition) apparatus that is a film forming apparatus that performs film forming processing using plasma.

The plasma processing apparatus 100 has a processing container (chamber) 1 that accommodates a substrate W, and generates surface waves near the inner wall surface of the top wall of the processing container 1 by microwaves radiated into the processing container 1. CVD film formation is performed on the substrate W using plasma. An example of a film formed by CVD film formation is a Si-containing film such as a silicon nitride film (SiN film). Note that, although a semiconductor wafer is exemplified as the substrate W, it is not limited to a semiconductor wafer, and may be other substrates such as an FPD substrate or a ceramic substrate.

The plasma processing apparatus 100 includes, in addition to the processing container 1 , a plasma source 2 , a gas supply mechanism 3 , and a control section 4 .

The processing container 1 has a substantially cylindrical container main body 10 with an open top, and a top wall portion 20 that closes the top opening of the container main body 10. Inside the processing container 1, a stage 11 on which a substrate W is placed is provided horizontally, and a plasma processing space is formed above the stage 11. The container body 10 is made of a metal material such as aluminum or stainless steel, and is grounded. The top wall portion 20 is made of a metal material such as aluminum or stainless steel and has a disk shape. When the container body 10 and the top wall portion 20 are made of aluminum, the surfaces may be anodized.

A seal ring 129 is interposed at the contact surface between the container body 10 and the top wall portion 20, thereby airtightly sealing the inside of the processing container 1. Furthermore, an yttria (Y ₂ O ₃ ) film 150 is formed on the surface of the area of the inner wall of the processing container 1 including the top wall portion 20 . The Y ₂ O ₃ coating 150 may be a thermally sprayed coating. The Y ₂ O ₃ film 150 is formed as a plasma-resistant film, and functions as a Y ₂ O ₃ portion for forming a protective film on the stage 11, as will be described later.

A stage 11 provided within the processing container 1 is supported by a cylindrical support member 12 erected at the center of the bottom of the processing container 1 . The upper surface of the stage 11 becomes a substrate mounting surface. The stage 11 is made of a material containing aluminum (Al), such as aluminum nitride (AlN), which is an insulating ceramic. Further, the material constituting the stage 11 may be alumina (Al ₂ O ₃ ), which is an insulating ceramic that also contains Al, or may be metal aluminum. The support member 12 may be made of metal or ceramics. When the support member 12 is made of metal, an insulating member 12 a is interposed between the support member 12 and the bottom of the processing container 1 .

A heater 13 is provided inside the stage 11, and a heater power source 14 is connected to the heater 13. By supplying power to the heater 13 from the heater power supply 14, the stage 11 is heated to an arbitrary temperature up to, for example, 700°C. The stage 11 is provided with three elevating pins (not shown) for elevating the substrate W, and the substrate W is delivered with the elevating pins protruding from the stage 11. . Note that the stage 11 may be provided with an electrostatic chuck for electrostatically adsorbing the substrate W, a gas flow path for supplying heat transfer gas to the back surface of the substrate W, and the like. Alternatively, an electrode may be provided on the stage 11, and a high frequency bias for drawing ions in the plasma may be applied to the electrode.

An exhaust pipe 15 is connected to the bottom of the processing container 1, and an exhaust device 16 including a vacuum pump is connected to the exhaust pipe 15. When the exhaust device 16 is operated, the inside of the processing container 1 is evacuated, thereby rapidly reducing the pressure inside the processing container 1 to a predetermined degree of vacuum. A side wall of the processing container 1 is provided with a loading/unloading port 17 for loading/unloading the substrate W, and a gate valve 18 for opening/closing the loading/unloading port 17 .

The plasma source 2 is for generating microwaves and radiating the generated microwaves into the processing container 1 to generate plasma, and includes a microwave output section 30 and a microwave supply section 40.

The microwave output unit 30 includes a microwave power source, a microwave oscillator that oscillates microwaves, an amplifier that amplifies the oscillated microwaves, and a distributor that distributes the amplified microwaves to a plurality of parts. Then, the microwave is distributed to multiple parts and output.

The microwave output from the microwave output section 30 is radiated into the processing container 1 through the microwave supply section 40 . Further, a gas is supplied into the processing container 1 as described later, and the supplied gas is excited by the introduced microwaves to form surface wave plasma.

The microwave supply section 40 transmits the microwave output from the microwave output section 30 and supplies it into the chamber 1 . The microwave supply section 40 includes a plurality of amplifier sections 42, a central microwave introduction section 43a arranged at the center of the ceiling wall section 20, and six peripheral microwaves arranged at equal intervals around the periphery of the ceiling wall section 20. It has a wave introduction part 43b. The plurality of amplifier sections 42 amplify the microwaves distributed by the distributor of the microwave output section 30, and correspond to each of the central microwave introduction section 43a and the six peripheral microwave introduction sections 43b. provided. The central microwave introducing section 43a and the six peripheral microwave introducing sections 43b have the function of radiating the microwave output from the amplifier section 42 provided correspondingly into the processing container 1 and the function of matching impedance. have

The central microwave introduction section 43a and the peripheral microwave introduction section 43b are configured by coaxially arranging a cylindrical outer conductor 52 and a rod-shaped inner conductor 53 provided at the center thereof. A microwave power is supplied between the outer conductor 52 and the inner conductor 53, forming a microwave transmission path 44 through which microwaves propagate.

The central microwave introduction section 43a and the peripheral microwave introduction section 43b are provided with a pair of slugs 54 and an impedance adjustment member 140 located at the tip thereof. By moving the slug 54, the impedance of the load (plasma) inside the processing container 1 is matched to the characteristic impedance of the microwave power source in the microwave output section 30. The impedance adjustment member 140 is made of a dielectric material, and is adapted to adjust the impedance of the microwave transmission line 44 based on its dielectric constant.

The central microwave introduction section 43a further includes a slow wave material 121, a slot antenna 124 having a slot 122, and a dielectric member 123. Furthermore, the peripheral microwave introduction section 43b further includes a slow wave material 131, a slot antenna 134 having a slot 132, and a dielectric member 133. The slow-wave materials 121 and 131 are provided on the upper surface of the ceiling wall portion 20, and the dielectric members 123 and 133 are provided inside the ceiling wall portion 20. The slots 122 and 132 are provided in a portion between the slow-wave material 121 and the dielectric member 123 of the top wall portion 20 and a portion between the slow-wave material 131 and the dielectric member 133 of the top wall portion 20, respectively. The portions in which these slots are formed become slot antennas 124 and 134.

The slow-wave materials 121 and 131 have a disk shape, are arranged so as to surround the tip of the inner conductor 53, and have a dielectric constant greater than that of a vacuum, and are made of, for example, quartz or alumina (Al ₂ O ₃ ). It is made of ceramics such as, fluororesins such as polytetrafluoroethylene, and polyimide resins. The slow-wave materials 121 and 131 have the function of making the wavelength of the microwave shorter than that in a vacuum, thereby making the antenna smaller. The slow wave materials 121 and 131 can adjust the phase of the microwave depending on their thickness, and their thicknesses are adjusted so that the slot antennas 124 and 134 become the "harass" of the standing wave, minimizing reflection. , so that the radiated energy of slot antennas 124 and 134 is maximized.

The dielectric members 123 and 133, like the slow wave materials 121 and 131, are made of, for example, quartz, ceramics such as alumina (Al ₂ O ₃ ), fluororesin such as polytetrafluoroethylene, or polyimide resin. . The dielectric members 123 and 133 are fitted into a space formed inside the top wall 20, and a concave window 21 is provided on the lower surface of the top wall 20 at a portion corresponding to the dielectric members 123 and 133. is formed. Therefore, the dielectric members 123 and 133 are exposed in the processing chamber 1 and function as dielectric windows that supply microwaves to the plasma generation space U.

Note that the number of peripheral microwave introducing portions 43b and dielectric members 133 is not limited to six, and may be two or more, but three or more is preferable. Further, the configuration of the microwave supply unit is not limited to the configuration of the microwave supply unit 40, but may be a configuration using other types of antennas such as a monopole antenna instead of using the slot antennas 124 and 134, for example. Good too.

The gas supply mechanism 3 supplies processing gas for plasma processing into the processing container 1 . As the processing gas, a gas for film formation such as a source gas or a reaction gas, and a fluorine-containing gas for cleaning the inside of the processing container 1 are used. Further, the fluorine-containing gas is also used for plasma treatment for forming a protective film on the surface of the stage 11, which will be described later.

For example, when forming a Si-containing film such as a SiN film, a Si-containing gas as a raw material gas and a reactive gas such as a nitriding gas can be used as the film-forming gas, and a cleaning gas NF ₃ gas excited by plasma can be used as a source. Further, NF ₃ gas plasma can also be used for plasma treatment for forming a protective film on the surface of the stage 11.

The gas supply mechanism 3 includes a gas supply section 61, a gas supply pipe 62 that supplies gas from the gas supply section 61, a gas flow path 63 provided in the ceiling wall section 20, and discharges gas from the gas flow path 63. It has a gas discharge port 64. A plurality of gas discharge ports 64 are provided around the dielectric members 123 and 133 of the window portion 21 of the ceiling wall portion 20 (see FIG. 2). Note that the gas supply mechanism 3 is not limited to one that discharges gas from the ceiling wall portion 20 as in this example. For example, in forming a Si-containing film, there are cases where it is desired to avoid converting the Si-containing gas, which is the raw material gas, into plasma as much as possible. It may be supplied near the.

The control unit 4 controls the operation and processing of each component of the plasma processing apparatus 100, for example, the gas supply of the gas supply mechanism 3, the phase and output of the microwave of the plasma source 2, the exhaust by the exhaust device 16, and the like. The control unit 4 is typically a computer and includes a main control unit, an input device, an output device, a display device, and a storage device. The main control unit includes a CPU (central processing unit), RAM, and ROM. The storage device has a computer-readable storage medium such as a hard disk, and is configured to record and read information necessary for control. In the control unit 4, the CPU controls the plasma processing apparatus 100 by using the RAM as a work area and executing programs such as processing recipes stored in a ROM or a storage medium of a storage device.

Next, plasma processing in the plasma processing apparatus 100 configured as above will be explained.

When performing a film formation process in the plasma processing apparatus 100, first, precoating is performed without carrying the substrate W into the processing chamber 1 (precoat step). Next, the substrate W is carried into the processing container 1 and film formation is performed (film formation process). Next, the inside of the processing container 1 is cleaned with the substrate W being carried out from the processing container 1 (cleaning step).

The precoating process is performed prior to the film forming process. In the pre-coating process, a film formed on the substrate W in the film-forming process or a pre-coating film containing a component of the film is coated on at least the surface of the stage 11 inside the processing vessel 1 in the absence of the substrate W in the processing vessel 1 . to be deposited. At this time, the precoat film is also deposited on the side walls and the top wall portion 20 of the processing container 1 . As the precoat film, the same material as the film to be formed on the substrate W or the material containing the components of the film to be formed can be used. For example, if the film to be formed is a SiN film, it may be the same SiN film, or it may be another Si-based film such as a SiCN film, a SiON film, or a SiOC film.

The film forming process is performed continuously on one substrate W or on a plurality of substrates W after the precoating process is performed. An example of the plurality of substrates W is up to about 100 substrates. Although the film to be formed is not particularly limited, a silicon (Si)-containing film, such as a SiN film, is exemplified as a suitable example. Other Si-containing films such as SiCN film, SiO ₂ film, SiON film, etc. may also be used.

When forming a SiN film, a Si-containing gas and a nitrogen-containing gas can be used as the film-forming gas. As the Si-containing gas, for example, a silane compound gas such as monosilane (SiH ₄ ) gas, disilane (Si ₂ H ₆ ) gas, or trimethylsilane (SiH(CH ₃ ) ₃ ) gas can be used. Further, as the nitrogen-containing gas, for example, ammonia (NH ₃ ) gas, nitrogen (N ₂ ) gas, etc. can be used. In the case of a SiCN film, a gas containing carbon may be used as the film-forming gas to the Si-containing gas and nitrogen-containing gas as described above. Examples of carbon-containing gases include ethylene (C ₂ H ₄ ) gas, acetylene (C ₂ H ₂ ) gas, ethane (C ₂ H ₆ ) gas, propylene (C ₃ H ₆ ) gas, and trimethylsilane ((CH ₃ ) ₃ A hydrocarbon-based gas such as SiH) gas can be used. In the case of a SiO ₂ film, a Si-containing gas and an oxygen-containing gas can be used. As the Si-containing gas, the above-mentioned silane compound gas can be used. Further, as the oxygen-containing gas, for example, oxygen (O ₂ ) gas, nitrogen monoxide (NO) gas, nitrous oxide (N ₂ O) gas, etc. can be used. In the case of a SiON film, a gas containing nitrogen as described above can be used as a film-forming gas to the Si-containing gas and oxygen-containing gas as described above. In either case, other gases such as argon (Ar) gas and helium (He) gas may be used as the diluting gas or plasma generating gas.

The film to be formed is not limited to a Si-containing film, and may be, for example, a Ti-based film such as a Ti film or a TiN film, or a carbon film.

In the film forming process, first, the gate valve 18 is opened, and the substrate W held on a transfer arm (not shown) is carried into the processing chamber 1 through the carry-in/out port 17, placed on the stage 11, and then the gate valve 18 is opened. Close valve 18. At this time, the stage 11 is heated by the heater 13, and the temperature of the substrate W on the stage 11 is controlled. When forming the SiN film described above, the temperature of the substrate W is preferably 500° C. or higher. More preferably the temperature is 500 to 650°C. Then, the above-mentioned gases are introduced into the processing container 1 according to the film to be formed, the pressure inside the processing container 1 is controlled, and the film forming process is performed by plasma CVD. The pressure inside the processing chamber 1 can be arbitrarily selected depending on the distance from the plasma source to the substrate W, how the plasma spreads, the film formation rate, the film thickness to be formed, and the like. When the film to be formed is a SiN film, a pressure of 266 Pa or less can be used.

To generate plasma, gas is introduced into the processing container 1 while microwave output section 30 of plasma source 2 outputs microwaves. At this time, the microwaves distributed and output from the microwave output section 30 are amplified by the amplifier section 42 of the microwave supply section 40, and then transmitted through the central microwave introduction section 43a and the peripheral microwave introduction section 43b. Ru. The transmitted microwaves are then transmitted through the slow wave materials 121 and 131, the slots 122 and 132 of the slot antennas 124 and 134, and the dielectric members 123 and 133, which are microwave transmission windows, and are radiated into the processing container 1. be done. At this time, impedance is automatically matched by moving the slug 54, and microwaves are radiated with substantially no power reflection. The radiated microwaves propagate on the surface of the ceiling wall portion 20 as surface waves. The gas introduced into the processing container 1 is excited by the electric field of the microwave, and surface wave plasma is formed in the plasma generation space U directly below the top wall portion 20 within the processing container 1. For example, a SiN film is formed on the substrate W by plasma CVD using this surface wave plasma.

In the plasma processing apparatus 100 of this embodiment, the substrate W is disposed in a region apart from the plasma generation region, and the substrate W is supplied with plasma diffused from the plasma generation region, so that essentially low It becomes a high-density plasma at the electron temperature. Since the electron temperature of the plasma is controlled to be low, film formation can be performed without damaging the film to be formed or the elements of the substrate W, and high-quality films can be obtained with high-density plasma. . In addition, the film quality improves as the film formation temperature increases, so if the film to be formed is a SiN film, an even higher quality film can be formed by increasing the film formation temperature to 500°C or higher as described above. can do.

After forming a film such as a SiN film as described above, the substrate W is carried out from the processing container 1. When performing film formation processing on a plurality of substrates W, the above-described operations are repeated. By performing such processing on a predetermined number of substrates W, the film forming process is completed.

After the film forming process as described above, a cleaning process is performed. As shown in FIG. 3, a precoat film 202 and a deposit 201 having the same components as the film 200 formed on the substrate W are deposited in the processing container 1 after the film forming process. If the next film is formed with these deposited, it will cause particles, etc., so a cleaning step is performed to clean and remove these. Note that in FIG. 3, the Y ₂ O ₃ film 150 is omitted.

The cleaning step is performed using a fluorine-containing gas. For example, radicals or ions of NF ₃ gas excited by plasma can be used as the fluorine-containing gas. The plasma at this time may be generated using the plasma source 2 of the plasma processing apparatus 100 instead of a remote plasma separately provided for cleaning. NF ₃ gas is supplied into the processing container 1 from the gas supply mechanism 3 . NF ₃ gas may be diluted with Ar gas or He gas. Further, in order to adjust the cleaning speed, chlorine (Cl ₂ ) gas, O ₂ gas, N ₂ gas, hydrogen bromide (HBr) gas, carbon tetrafluoride (CF ₄ ) gas, etc. may be added. NF ₃ gas excited by plasma can be suitably used, for example, when the film formed on the substrate W is a Si-containing film such as a SiN film.

As _the fluorine-containing gas used for cleaning, gases other than NF 3 gas, such as F ₂ gas, CF-based gas, and ClF ₃ gas, can also be used. Other fluorine-containing gases do not need to be excited by plasma, and may be diluted with Ar gas or He gas. Further, other additive gases may be added to the fluorine-containing gas. These fluorine-containing gases can be selected depending on the material of the film to be attached and deposited in the processing container 1.

By the way, in the cleaning process, if a protective film is not formed on the stage 11 and the stage temperature reaches a high temperature of, for example, 450° C. or higher, the stage 11 will be exposed to a fluorine-containing gas as a cleaning gas during overcleaning after cleaning is completed. is damaged. That is, the fluorine-containing gas that is the cleaning gas and the Al-containing substance that constitutes the stage 11 react to generate aluminum fluoride (AlF _x ) represented by aluminum trifluoride (AlF ₃ ), which is sublimed. do. The sublimated AlF _x is deposited on a cold spot (100° C. or less) inside the processing container 1, and there is a possibility that it becomes particles and adheres to the substrate W during the next film formation, which may have an adverse effect.

Specifically, when forming a SiN film, as shown in FIG. 4, a SiN film 204 is deposited on the surface of the stage 11 made of AlN after film formation, and in the cleaning process, a fluorine-containing gas is used. The deposited SiN film 204 is removed by the following reaction using NF ₃ gas excited by plasma.
SiN (solid) + F ^* (gas) → SiF ₄ (gas) + NF ₃ (gas)
Then, during overcleaning after cleaning of the SiN on the stage 11 is completed, if the stage temperature reaches a high temperature of, for example, 450° C. or higher, the stage 11 will be damaged by F ^* . That is, the following reaction occurs, and AlF ₃ is produced and sublimed.
AlN (solid) + F ^* (gas) → AlF ₃ (gas) + NF ₃ (gas)
There is a possibility that the sublimated AlF ₃ will be deposited on a cold spot in the processing container 1 and become particles during the next film formation. Such damage to the stage 11 becomes more noticeable as the temperature increases.

Therefore, in this embodiment, the stage 11 is assumed to have a protective film mainly composed of YF ₃ formed on its surface. A protective film mainly composed of YF ₃ can be formed by plasma treatment using plasma of a fluorine-containing gas. By forming a protective film mainly composed of YF ₃ on the surface of the stage 11, generation of AlF _x due to the reaction between the fluorine-containing gas and the stage 11 is suppressed.

A plasma processing method for forming a protective film on the stage surface will be described below. FIG. 5 is a diagram for explaining a plasma processing method for forming a protective film on the stage surface. First, as described above, a fluorine-containing gas is introduced into the processing chamber 1 in which the Y ₂ O ₃ film 150 is previously formed as a Y ₂ O ₃ portion on the surface of the inner wall region including the top wall portion 20 on which plasma acts. A plasma (F ^* ) is generated (FIG. 5(a)). The generated plasma reacts with the Y ₂ O ₃ coating 150 on the top wall portion 20 of the processing container 1 to generate a gas containing YF ₃ (FIG. 5(b)). Then, a gas containing YF ₃ is solidified and deposited on the surface of the stage 11 to form a protective film 160 mainly composed of YF ₃ (FIG. 5(c)). The above processing is performed with no substrate placed on the stage 11.

As the fluorine-containing gas used to form the protective film 160, NF ₃ gas can be suitably used as in the cleaning process. NF ₃ gas may be diluted with Ar gas or He gas. Furthermore, the fluorine-containing gas may be F ₂ gas, CF-based gas, ClF ₃ gas, or the like. The fluorine-containing gas used at this time may be the same as or different from that used in the cleaning step.

The thickness of the protective film 160 may be in the range of 10 to 100 nm, for example 50 nm. In order to form the protective film 160 with such a thickness, plasma treatment is performed for a total of 1 to 24 hours, for example. The protective film 160 mainly composed of YF ₃ may be YF ₃ alone, or may contain other components such as O in addition to YF ₃ . Further, the stage temperature when performing the plasma treatment at this time may be 400° C. or lower, preferably 320° C. or lower, when the fluorine-containing gas is NF ₃ gas.

By forming the protective film 160 mainly composed of YF ₃ on the surface of the stage 11 in this way, damage caused by a fluorine-containing gas such as NF ₃ gas (F ^* ) excited by plasma on the stage 11 during the cleaning process can be prevented. can be suppressed. Therefore, the generation of AlF _x can be suppressed, and the generation of particles during film formation by vapor deposition of AlF _x is suppressed.

In other words, since YF ₃ has a significantly lower vapor pressure than AlF ₃ and is less likely to sublime, forming the protective film 160 mainly made of YF ₃ suppresses the reaction with fluorine-containing gases, making it difficult to sublime with substances containing Al. Sublimation of AlF _x from the configured stage 11 can be suppressed. FIG. 6 is a diagram showing a comparison of the vapor pressure curve of YF ₃ with that of AlF ₃ . This figure shows that YF ₃ has a vapor pressure that is ten orders of magnitude lower than that of AlF ₃ and is difficult to sublimate.

In this embodiment, the plasma treatment for forming the protective film 160 mainly containing YF ₃ is performed by generating microwave plasma in the processing container 1. Plasma can be applied directly to the Y ₂ O ₃ film 150. Thereby, the protective film 160 mainly composed of YF ₃ can be formed on the surface of the stage 11 relatively easily.

Conventionally, in a PECVD apparatus used for forming a SiN film, capacitively coupled plasma is used for CVD film formation, and remote plasma of NF ₃ gas, which is a fluorine-containing gas, is generally used for cleaning processing. However, when remote plasma is used to form the protective film, it is difficult to directly expose the Y ₂ O ₃ film 150 to NF ₃ plasma, and YF ₃ is not sufficiently generated. On the other hand, in this embodiment, as described above, the microwave plasma is applied directly to the Y ₂ O ₃ film 150, so that the activation energy necessary for the generation of YF ₃ can be sufficiently supplied, and the stage A protective film 160 mainly composed of YF ₃ can be formed on the surface of the substrate 11 relatively easily. Furthermore, since microwave plasma is a high-density plasma, F ^* can be efficiently generated and YF ₃ can be easily generated.

At this time, the formation of the protective film 160 mainly composed of YF ₃ is optimized by adjusting the microwave plasma conditions (for example, the pressure inside the processing chamber 1, the microwave power, the NF ₃ gas flow rate, and the stage temperature). can do. When forming the protective film 160, microwave plasma is applied to the Y ₂ O ₃ film 150 to generate YF ₃ gas, so it is preferable to use a higher plasma energy than during the cleaning process. In particular, among the above conditions _, the influence _of the _pressure inside the processing container 1 is large. It becomes easier to deposit _YF3 on top. From this point of view, the pressure inside the processing container 1 is preferably 20 Pa or less. Furthermore, since the higher the microwave power is, the easier it is to deposit YF ₃ , it is preferable that the microwave power be 500 W or more per microwave introduction section. In the cleaning process, for example, the pressure inside the processing container 1 is about 1000 Pa and the power per microwave introduction part is about 450 W. However, in forming the protective film 160, as described above, the cleaning process Low pressure and high power conditions are preferred.

Furthermore, the film thickness distribution of the protective film 160 on the surface of the stage 11 may be adjusted by changing the plasma conditions between the center portion and the peripheral portion of the stage. For example, in the cleaning process, the center part of the stage 11 is more likely to be overcleaned, so the center part is made thicker than the peripheral part. The film thickness adjustment at this time can be performed, for example, by changing the power of the central microwave introducing section 43a and the peripheral microwave introducing section 43b, and by increasing the power of the central microwave introducing section 43a, the stage It is possible to increase the thickness of the film at the center of the film 11.

In this embodiment, by subjecting the Y ₂ O ₃ film 150 to plasma treatment, the protective film 160 mainly composed of YF ₃ can be formed on the stage 11 relatively easily and at low cost. When forming the protective film 160, the Y ₂ O ₃ film 150 is consumed, but by reducing the amount of the Y ₂ O ₃ film 150 consumed for forming the protective film 160 to about 5%, The influence on the life of the Y ₂ O ₃ film 150 can be made relatively small. Note that the Y ₂ O ₃ film 150 is replaced when the thickness of the Y ₂ O ₃ film 150 reaches a predetermined lifetime thickness.

In the case of an unused plasma processing apparatus 100, a protective film 160 mainly made of YF ₃ is first formed on the surface of the stage 11 by the plasma processing as described above. Thereafter, the above-described precoating process, film forming process, and cleaning process are repeated. This suppresses the AlF _x production reaction on the surface of the stage 11 caused by the fluorine-containing plasma during the cleaning process, and suppresses the adhesion of particles to the substrate W during the film forming process.

In addition, in the case of the plasma processing apparatus 100 after performing the film forming process several times, after the film forming process, a cleaning process is performed using a fluorine-containing gas, for example, NF ₃ gas excited by the plasma, and the stage 11 Then, a film deposited on the processing container 1, for example, a SiN film, is removed. At this time, AlF _x is generated on the surface of the stage 11 , and if the film forming process is continued as is, AlF _x will be deposited on the processing container 1 . For this reason, after the cleaning process, a heating process is performed to sublimate and remove _AlFx , so that the stage 11 and the processing container 1 are free of deposits. In the heating step, the temperature of the stage 11 is set to, for example, 500° C. or higher and lower than 600° C. to sublimate AlF _x . After this heating step, a protective film 160 mainly made of YF ₃ is formed on the surface of the stage 11 by the plasma treatment described above. After that, the above-described precoating process, film forming process, and cleaning process are repeated.

An experiment was conducted to confirm whether a protective film could actually be formed on the stage surface using plasma treatment. Here, using the _plasma processing apparatus 100 shown in _{FIG .} Plasma treatment was performed under the following conditions: internal pressure: 20 Pa, power of the microwave introduction sections 43a and 43b: 500 W, and temperature: 320°C. After the treatment, the sample chip was confirmed using a TEM image, and as shown in FIG. 7, it was confirmed that a film with a thickness of about 50 nm was formed. When the composition of the film was analyzed, it was confirmed that the main components of the film were Y and F, as shown in FIG. From this result, it was confirmed that a protective film mainly composed of YF ₃ was formed by the plasma treatment.

In the plasma processing apparatus 100 of FIG _. 1, a Y ₂ O ₃ film 150 is provided as the Y ₂ O ₃ portion on the surface of a region including the top wall portion ₂₀ of the inner wall of the processing chamber 1; is not limited to this, and may be provided at a position where plasma acts. For example, as shown in FIG. 9, it may be a Y ₂ O ₃ film 151 formed on the surfaces of the dielectric members 123 and 133. Further, as shown in FIG. 10, dielectric members 123a and 133a made of Y ₂ O ₃ may be provided in place of the dielectric members 123 and 133, and these may be used as the Y ₂ O ₃ portion. Further, the Y ₂ O ₃ portion may be two or more of the Y ₂ O ₃ film 150, the Y ₂ O ₃ film 151, and the dielectric members 123a and 133a.

Although the embodiments have been described above, the embodiments disclosed this time should be considered to be illustrative in all respects and not restrictive. The embodiments described above may be omitted, replaced, or modified in various forms without departing from the scope and spirit of the appended claims.

For example, in the above embodiment, the plasma processing apparatus is exemplified as one that forms a film using surface wave plasma generated by radiating microwaves into the processing container from a plurality of microwave introduction parts, but the invention is not limited to this. It's not a thing. The number of microwave introduction parts may be one, and the plasma treatment is particularly preferably one in which plasma is generated by emitting microwaves, but the present invention is not limited to this, and for example, capacitively coupled plasma (CCP) can be used. Various other plasmas may be used, such as inductively coupled plasma (ICP), magnetic resonance (ECR) plasma, etc.

Further, in the above embodiments, the plasma processing for the substrate is described as a film forming process, but the plasma processing is not limited to a film forming process as long as the cleaning process is performed using a fluorine-containing gas after the plasma processing of the substrate.

1; Processing container 2; Plasma source 3; Gas supply mechanism 4; Control section 11; Stage 20; Top wall section 30; Microwave output section 40; Microwave supply section 100; Film forming apparatus 123a, _133a ; _Y2O3 Dielectric member (Y ₂ O ₃ parts) composed of
150, 151; Y ₂ O ₃ film (Y ₂ O ₃ part)
W; Substrate

Claims (18)

a processing container, a stage made of a material containing aluminum on which a substrate is placed within the processing container, a plasma source that generates plasma within the processing container, and a portion of the processing container on which the plasma acts. A plasma processing method in a plasma processing apparatus having a formed Y ₂ O ₃ portion,
generating a fluorine-containing gas plasma in the processing container;
generating YF ₃ gas by a reaction between the plasma of the fluorine-containing gas and the Y ₂ O ₃ moiety;
Depositing YF ₃ on the stage surface to form a protective film mainly composed of YF ₃ ;
A plasma processing method comprising: The plasma processing method according to claim 1, wherein the fluorine-containing gas is _NF3 gas. 3. The plasma processing method according to claim 1, wherein the plasma source generates plasma using microwaves. 4. The plasma processing method according to claim 3, wherein the pressure within the processing container when generating the plasma of the fluorine-containing gas is 20 Pa or less. 4. The plasma processing method according to claim 3, wherein the plasma source includes a microwave transmission path, a slot antenna, and a dielectric member, and has a microwave introducing section that introduces microwaves into the processing container. The Y ₂ O ₃ portion includes a Y ₂ O ₃ film formed in a region including the top wall of the processing container, a Y ₂ O ₃ film formed on the surface of the dielectric member of the microwave introducing section, and , one or more of the dielectric members of the microwave introducing section. 6. The plasma processing method according to claim 5, wherein a plurality of the microwave introducing sections are provided, and the thickness distribution of the protective film is adjusted by adjusting the power of these microwave introducing sections. Generating a plasma of the fluorine-containing gas in the processing container, generating the YF ₃ gas, and forming the YF ₃ -based protective film are performed on the unused or the stage and the 3. The plasma processing method according to claim 1, wherein the plasma processing method is performed on the plasma processing apparatus in a state where no deposits exist in the processing container. Generating the plasma of the fluorine-containing gas in the processing chamber, generating the YF ₃ gas, and forming the protective film mainly composed of YF ₃ are performed when the substrate is placed on the stage. 3. The plasma processing method according to claim 1, wherein the plasma processing method is carried out in a state where the plasma processing method is not performed. a processing container, a stage made of a material containing aluminum on which a substrate is placed within the processing container, a plasma source that generates plasma within the processing container, and a portion of the processing container on which the plasma acts. A plasma processing method in a plasma processing apparatus having a formed Y ₂ O ₃ portion,
forming a protective film mainly composed of YF ₃ on the surface of the stage by plasma treatment;
placing a substrate on the stage and performing plasma processing on the substrate;
After the plasma processing on the substrate, cleaning the inside of the processing container with a fluorine-containing gas;
has
Forming a protective film mainly composed of YF ₃ on the surface of the stage
generating a fluorine-containing gas plasma in the processing container;
generating YF ₃ gas by a reaction between the plasma of the fluorine-containing gas and the Y ₂ O ₃ moiety;
Depositing YF ₃ on the stage surface to form a protective film mainly composed of YF ₃ ;
A plasma processing method comprising: 11. The plasma processing method according to claim 10, wherein the plasma processing on the substrate is a film forming process. The plasma processing method according to claim 10 or 11, wherein the fluorine-containing gas is _NF3 gas. The plasma processing method according to claim 10 or 11, wherein the plasma source generates plasma using microwaves. Forming a protective film mainly composed of YF ₃ on the surface of the stage by the plasma processing is performed on the unused plasma processing apparatus,
12. The plasma processing method according to claim 10, wherein thereafter, performing the plasma processing on the substrate and cleaning the inside of the processing container with a fluorine-containing gas are repeatedly performed. After performing the plasma processing on the substrate in a state where the protective film is not formed on the stage, cleaning the inside of the processing container with a fluorine-containing gas,
After the cleaning, the method further comprises removing deposits on the stage by heating,
After removing the deposits by heating, forming a protective film mainly composed of YF ₃ on the surface of the stage using plasma of the fluorine-containing gas;
12. The plasma processing method according to claim 10, wherein the plasma processing and the cleaning are repeated on the substrate. 12. The method according to claim 10 or 11, wherein forming the protective film mainly composed of YF ₃ on the surface of the stage by the plasma of the fluorine-containing gas is performed in a state where the substrate is not placed on the stage. The plasma treatment method described. a processing container;
a stage made of a material containing aluminum on which a substrate is placed within the processing container;
a plasma source that generates plasma within the processing container;
a Y ₂ O ₃ portion formed in a portion of the processing container where the plasma acts;
a control unit;
The control unit includes:
generating a fluorine-containing gas plasma in the processing container;
generating YF ₃ gas by a reaction between the plasma of the fluorine-containing gas and the Y ₂ O ₃ moiety;
Depositing YF ₃ on the stage surface to form a protective film mainly composed of YF ₃ ;
A plasma processing device that controls the process so that it is carried out. A stage on which a substrate is placed within a processing container in which a fluorine-containing gas plasma is generated, the stage comprising:
A stage made of a material containing aluminum, with a protective film mainly composed of _YF3 formed on the surface.

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