Film forming apparatus and film forming method

Abstract

To suppress an influence of an aluminum fluoride on film formation, the aluminum fluoride being generated by a reaction between a fluorine-containing gas as a cleaning gas and an aluminum-containing stage when an interior of a processing container is cleaned with the fluorine-containing gas after film forming processing.SOLUTION: A film forming apparatus includes: a processing container; an aluminum-containing stage which is provided in the processing container and on which a substrate is placed; a heating mechanism which heats the stage; a gas supply mechanism which supplies a film formation gas and a fluorine-containing gas for cleaning into the processing container; and a cover member which is provided to cover portions of the stage other than a substrate placing surface. When, after the film formation gas is supplied into the processing container to form a film on the substrate, the fluorine-containing gas is supplied into the processing container to clean the inside of the processing container, the cover member adsorbs an aluminum fluoride that is generated by a reaction between aluminum in the stage and the fluorine-containing gas and that sublimates in the processing container.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a film forming apparatus and a film forming method. [Background technology]

[0002] Patent Document 1 describes that in a microwave plasma processing apparatus, after a film formation process or the like is performed in a processing vessel, the inside of the processing vessel is cleaned using NF3 gas excited by plasma. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-216150 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a film formation apparatus and a film formation method that can suppress the effect of aluminum fluoride, which is generated by a reaction between a fluorine-containing gas (cleaning gas) and a mounting table containing aluminum, on film formation when cleaning the inside of a processing vessel with a fluorine-containing gas after a film formation process. [Means for solving the problem]

[0005] A film formation apparatus according to one aspect of the present disclosure includes a processing vessel, a mounting stage containing aluminum and arranged within the processing vessel for mounting a substrate thereon, a heating mechanism for heating the mounting stage, a gas supply mechanism for supplying a film formation gas and a fluorine-containing cleaning gas into the processing vessel, and a cover member arranged to cover a portion of the mounting stage other than a substrate mounting surface, the cover member has a cylindrical portion provided to cover a side surface of the mounting table, and an annular portion extending from the cylindrical portion toward the mounting table, the annular portion being provided in multiple stages;The cover member adsorbs aluminum fluoride that is produced by a reaction between aluminum on the mounting table and the fluorine-containing gas and that sublimates within the processing vessel when the film-forming gas is supplied into the processing vessel to form a film on the substrate and then the fluorine-containing gas is supplied into the processing vessel to clean the interior of the processing vessel. [Effects of the Invention]

[0006] According to the present disclosure, a film formation apparatus and a film formation method are provided that can suppress the effect on film formation of aluminum fluoride, which is generated by the reaction between the fluorine-containing gas used as cleaning gas and a mounting table containing aluminum, when cleaning the inside of a processing vessel with a fluorine-containing gas after a film formation process. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a cross-sectional view illustrating an example of a film forming apparatus according to an embodiment. [Figure 2] 2 is a cross-sectional view showing the AA section of the film forming apparatus of FIG. 1. [Figure 3] 3 is a flowchart illustrating a film forming method performed by the film forming apparatus according to the embodiment. [Figure 4] FIG. 10 is a schematic diagram for explaining a state inside the processing chamber after a film forming process. [Figure 5] FIG. 1 is a diagram for explaining the generation of AlFx during cleaning and the influence of the sublimation of the generated AlFx. [Figure 6] FIG. 1 is a diagram showing the relationship between the theoretical vapor pressure curve of AlF3 and the control pressure of a general processing vessel. [Figure 7] 1 is a cross-sectional view schematically showing a state in which AlFx is formed on the surface of a mounting table by cleaning with a fluorine-containing gas in a film-forming apparatus according to an embodiment. [Figure 8] FIG. 10 is a cross-sectional view schematically illustrating a state in which pre-coating is performed after a cleaning process in the film forming apparatus according to the embodiment. [Figure 9]FIG. 10 is a cross-sectional view schematically showing a state in which sublimated AlFx is adsorbed by a cover member in a film forming apparatus according to an embodiment. [Figure 10] 10 is a cross-sectional view showing a state in which a cleaning process is performed with a dummy substrate placed on a placement table in the film forming apparatus according to the embodiment. FIG. [Figure 11] FIG. 1 is a diagram showing the vapor pressure curve of YF3 in comparison with the vapor pressure curve of AlF3. [Figure 12] FIG. 10 is a cross-sectional view showing a schematic configuration of a film forming apparatus using a cover member according to another example. [Figure 13] FIG. 10 is a cross-sectional view showing a schematic configuration of a film forming apparatus using a cover member of yet another example. [Figure 14] FIG. 14 is a cross-sectional view showing a modification of the film forming apparatus of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, the embodiments will be specifically described with reference to the accompanying drawings.

[0009] FIG. 1 is a cross-sectional view showing an example of a film forming apparatus according to an embodiment, and FIG. 2 is a cross-sectional view showing the AA cross section of the film forming apparatus of FIG.

[0010] The film forming apparatus 100 is configured as a plasma processing apparatus that performs plasma processing using microwave plasma.

[0011] The film formation apparatus 100 has a processing vessel (chamber) 1 that accommodates a substrate W. The film formation apparatus 100 performs a film formation process on the substrate W by using surface wave plasma formed near the inner wall surface of the ceiling wall of the processing vessel 1 by microwaves radiated into the processing vessel 1. The film formed by the film formation process is not particularly limited, and an example thereof 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.

[0012] The film forming apparatus 100 includes a processing chamber 1, a plasma source 2, a gas supply mechanism 3, and a control unit 4.

[0013] The processing vessel 1 has a generally cylindrical vessel body 10 with an open top and a ceiling wall 20 that closes the top opening of the vessel body 10, forming a plasma processing space inside. The vessel body 10 is made of a metal material such as aluminum or stainless steel and is grounded. The ceiling wall 20 is made of a metal material such as aluminum or stainless steel and is disk-shaped. A seal ring 129 is interposed at the contact surface between the vessel body 10 and the ceiling wall 20, thereby hermetically sealing the interior of the processing vessel 1.

[0014] A mounting table 11 for mounting a substrate W thereon is horizontally disposed within the processing vessel 1 and is supported by a cylindrical support member 12 erected at the center of the bottom of the processing vessel 1. The upper surface of the mounting table 11 serves as a substrate mounting surface. The mounting table 11 is made of a material containing aluminum (Al), such as aluminum nitride (AlN), an insulating ceramic. The mounting table 11 may also be made of alumina (Al2O3), an insulating ceramic that also contains Al. The support member 12 may be made of either metal or ceramic. If the support member 12 is made of metal, an insulating member 12a is interposed between the support member 12 and the bottom of the processing vessel 1. A heater 13 is disposed within the mounting table 11 and is connected to a heater power supply 14. By supplying power from the heater power supply 14 to the heater 13, the mounting table 11 is heated to any temperature, for example, up to 700°C. The mounting table 11 is provided with three lifting pins (not shown) for raising and lowering the substrate W, and the substrate W is transferred with the lifting pins protruding from the mounting table 11. The mounting table 11 may also be provided with an electrostatic chuck for electrostatically attracting the substrate W, a gas flow path for supplying a gas for heat transfer to the backside of the substrate W, and the like. An electrode may also be provided on the mounting table 11, and a high-frequency bias may be applied to the electrode to attract ions in the plasma.

[0015] A cover member 140 is provided around the mounting table 11 to cover the entire mounting table 11 except for the substrate mounting surface. The cover member 140 adsorbs aluminum fluoride, which is produced by a reaction between the mounting table 11, which is made of an Al-containing substance, and a fluorine-containing cleaning gas during a cleaning process (described later). The aluminum fluoride is sublimated from the mounting table 11. In this example, the cover member 140 is provided at a distance from the mounting table 11. The cover member 140 includes a cylindrical portion 140a extending upward from the bottom of the processing vessel 1 to approximately the height of the mounting table 11, located outside the side surface of the mounting table 11, and an annular portion 140b extending from the upper end of the cylindrical portion 140a to a position near the outer periphery of the mounting table 11. The cylindrical portion 140a also covers the side surface of the support member 12. In FIG. 1, the cylindrical portion 140a is provided vertically and the annular portion 140b is provided horizontally, but they may be inclined.

[0016] An exhaust pipe 15 is connected to the bottom of the processing vessel 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 processing vessel 1 is evacuated, thereby quickly reducing the pressure inside the processing vessel 1 to a predetermined vacuum level. A load / unload port 17 for loading / unloading the substrate W and a gate valve 18 for opening / closing the load / unload port 17 are provided on the sidewall of the processing vessel 1.

[0017] The plasma source 2 generates microwaves and radiates the generated microwaves into the processing vessel 1 to generate plasma, and includes a microwave output unit 30, a microwave transmission unit 40, and a microwave radiation mechanism 50.

[0018] The microwave output unit 30 has 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 into multiple parts, and then distributes the microwaves into multiple parts and outputs them.

[0019] The microwaves output from microwave output unit 30 are radiated into processing vessel 1 through microwave transmission unit 40 and microwave radiation mechanism 50. Gas is supplied into processing vessel 1 as described below, and the supplied gas is excited by the introduced microwaves to form surface wave plasma.

[0020] The microwave transmission unit 40 transmits the microwaves output from the microwave output unit 30. The microwave transmission unit 40 has a plurality of amplifier units 42, a central microwave introduction unit 43a arranged in the center of the top wall unit 20, and six peripheral microwave introduction units 43b arranged at equal intervals on the periphery of the top wall unit 20. The plurality of amplifier units 42 amplify the microwaves distributed by the distributor of the microwave output unit 30, and are provided corresponding to the central microwave introduction unit 43a and the six peripheral microwave introduction units 43b, respectively. The central microwave introduction unit 43a and the six peripheral microwave introduction units 43b have the function of introducing the microwaves output from the amplifier units 42 provided correspondingly to the microwave radiation mechanism 50 and the function of matching impedance.

[0021] The central microwave introduction part 43a and the peripheral microwave introduction part 43b are configured by coaxially arranging a cylindrical outer conductor 52 and a rod-shaped inner conductor 53 provided at the center of the cylindrical outer conductor 52. Microwave power is supplied between the outer conductor 52 and the inner conductor 53, forming a microwave transmission path 44 through which microwaves propagate toward the microwave radiation mechanism 50.

[0022] The central microwave introduction part 43a and the peripheral microwave introduction part 43b are provided with a pair of slugs 54 and an impedance adjustment member 150 located at the tip of the slugs 54. By moving the slugs 54, the impedance of the load (plasma) in the processing vessel 1 is matched to the characteristic impedance of the microwave power source in the microwave output part 30. The impedance adjustment member 150 is made of a dielectric material and adjusts the impedance of the microwave transmission line 44 by its relative dielectric constant.

[0023] The microwave radiation mechanism 50 includes slow-wave materials 121 and 131, slot antennas 124 and 134 having slots 122 and 132, and dielectric members 123 and 133. The slow-wave materials 121 and 131 are provided at positions corresponding to the central microwave introduction portion 43a on the upper surface of the top wall portion 20 and the peripheral microwave introduction portion 43b on the upper surface of the top wall portion 20, respectively. The dielectric members 123 and 133 are also provided at positions corresponding to the central microwave introduction portion 43a and the peripheral microwave introduction portion 43b inside the top wall portion 20, respectively. The slots 122 and 132 are provided in a portion of the top wall portion 20 between the slow-wave material 121 and the dielectric member 123, and in a portion of the top wall portion 20 between the slow-wave material 131 and the dielectric member 133, respectively, and the portions where these slots are formed form the slot antennas 124 and 134.

[0024] The slow-wave materials 121 and 131 are disk-shaped and are arranged to surround the tip of the inner conductor 53. They have a dielectric constant greater than that of a vacuum, and are made of, for example, quartz, ceramics, fluorine-based resins such as polytetrafluoroethylene, or polyimide-based resins. The slow-wave materials 121 and 131 function to shorten the wavelength of the microwaves compared to that in a vacuum, thereby making the antennas smaller. The slow-wave materials 121 and 131 can adjust the phase of the microwaves by their thickness, and the thickness is adjusted so that the slot antennas 124 and 134 form the "bells" of the standing waves, minimizing reflection and maximizing the radiant energy of the slot antennas 124 and 134.

[0025] The dielectric members 123 and 133, like the slow-wave members 121 and 131, are made of, for example, quartz, ceramics such as alumina (Al2O3), fluorine-based resin such as polytetrafluoroethylene, or polyimide-based resin. The dielectric members 123 and 133 are fitted into a space formed inside the ceiling wall 20, and a concave window 21 is formed on the lower surface of the ceiling wall 20 in a portion corresponding to the dielectric members 123 and 133. Therefore, the dielectric members 123 and 133 are exposed inside the processing vessel 1 and function as a dielectric window that supplies microwaves to the plasma generation space U.

[0026] The number of peripheral microwave introduction portions 43b and dielectric members 133 is not limited to six, and may be two or more, but is preferably three or more.

[0027] As will be described later, the gas supply mechanism 3 supplies gas for film formation processing and gas for cleaning into the processing chamber 1. The gas supply mechanism 3 has a gas supply unit 61, a gas supply pipe 62 that supplies gas from the gas supply unit 61, a gas flow path 63 provided in the ceiling wall 20, and a gas outlet 64 that discharges gas from the gas flow path 63. A plurality of gas outlets 64 are provided around the dielectric members 123 and 133 of the window 21 of the ceiling wall 20 (see FIG. 2). Note that the gas supply mechanism 3 is not limited to one that discharges gas from the ceiling wall 20 as in this example.

[0028] The control unit 4 controls the operation and processing of each component of the film forming apparatus 100, such as the gas supply from the gas supply mechanism 3, the microwave frequency and output from the plasma source 2, and exhaust by the exhaust device 16. 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 has 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 required for control. In the control unit 4, the CPU uses the RAM as a working area to execute programs such as processing recipes stored in the ROM or the storage medium of the storage device, thereby controlling the film forming apparatus 100.

[0029] Next, a film formation method using the film formation apparatus 100 configured as above will be described. 3 is a flowchart showing a film formation method. As shown in FIG. 3, in the film formation apparatus 100, steps ST1, ST2, and ST3 are repeatedly performed. In step ST1, precoating is performed so that a precoat film is formed at least on the surface of the mounting table without loading a substrate W into the processing vessel 1. In step ST2, the substrate W is loaded into the processing vessel 1, and while heating the substrate W on the mounting table 11 containing Al, a film formation gas is supplied into the processing vessel 1 to form a film on one substrate W or on multiple substrates W consecutively. In step ST3, with the substrate W unloaded from the processing vessel 1, the inside of the processing vessel 1 is cleaned with a fluorine-containing gas.

[0030] The precoating process of step ST1 is performed prior to the film formation process. In the precoating process, without the substrate W present in the processing vessel 1, a film to be formed on the substrate W in the film formation process or a precoat film containing components of that film is deposited at least on the surface of the mounting table 11 inside the processing vessel 1. At this time, the precoat film is also deposited on the surfaces of the sidewalls and ceiling wall 20 of the processing vessel 1. The precoat film can be made of the same material as the film to be formed on the substrate W or a material containing components of the film to be formed. For example, if the film to be formed is a SiN film, the precoat film can be the same SiN film, or another Si-based film such as a SiCN film, a SiON film, or a SiOC film.

[0031] In the film formation process of step ST2, a film is formed on one substrate W or on multiple substrates W continuously in the processing chamber 1 after the pre-coating process of step ST1 has been performed. The number of substrates W may be up to about 100. The film to be formed is not particularly limited, but a silicon (Si)-containing film, such as a SiN film, is a suitable example. Other Si-containing films, such as a SiCN film, a SiO2 film, or a SiON film, may also be used.

[0032] When forming a SiN film, a Si-containing gas and a nitrogen-containing gas can be used as the film-forming gas. Examples of the Si-containing gas include silane-based compound gases such as monosilane (SiH4) gas, disilane (Si2H6) gas, and trimethylsilane (SiH(CH3)3) gas. Examples of the nitrogen-containing gas include ammonia (NH3) gas and nitrogen (N2) gas. When forming a SiCN film, a gas obtained by adding a carbon-containing gas to the Si-containing and nitrogen-containing gases described above can be used as the film-forming gas. Examples of the carbon-containing gas include hydrocarbon gases such as ethylene (C2H4) gas, acetylene (C2H2) gas, ethane (C2H6) gas, propylene (C3H6) gas, and trimethylsilane ((CH3)3SiH) gas. When forming a SiO2 film, a Si-containing gas and an oxygen-containing gas can be used. Examples of the Si-containing gas include silane-based compound gases described above. Examples of oxygen-containing gases that can be used include oxygen (O2) gas, nitric oxide (NO) gas, and nitrous oxide (NO) gas. In the case of a SiON film, the film-forming gas may be a Si-containing gas and an oxygen-containing gas, to which the nitrogen-containing gas described above has been added. In either case, argon (Ar) gas or helium (He) gas may be used as a dilution gas or plasma-generating gas.

[0033] The film to be formed is not limited to a Si-containing film, but may be, for example, a Ti-based film such as a Ti film or a TiN film, or a carbon film.

[0034] In the film formation process of step ST2, first, the gate valve 18 is opened, the substrate W held on the transfer arm (not shown) is loaded into the processing chamber 1 through the loading / unloading port 17, and placed on the mounting table 11. The gate valve 18 is then closed. At this time, the mounting table 11 is heated by the heater 13, and the temperature of the substrate W on the mounting table 11 is controlled. When forming the SiN film described above, the temperature of the substrate W is preferably 500°C or higher, more preferably 500 to 650°C. Then, the gases described above according to the film to be formed are introduced into the processing chamber 1, the pressure inside the processing chamber 1 is controlled, and the film formation 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, the spread of the plasma, the film formation rate, the film thickness, and the like. When the film to be formed is a SiN film, a pressure of 266 Pa or less can be used.

[0035] To generate plasma, microwaves are output from the microwave output unit 30 of the plasma source 2 while gas is being introduced into the processing vessel 1. The microwaves distributed and output from the microwave output unit 30 are amplified by the amplifier unit 42 of the microwave transmission unit 40 and then transmitted through the central microwave inlet 43a and the peripheral microwave inlet 43b. The transmitted microwaves then pass through the slow-wave members 121 and 131 of the microwave radiation mechanism 50, the slots 122 and 132 of the slot antennas 124 and 134, and the dielectric members 123 and 133 serving as microwave-transmitting windows, before being radiated into the processing vessel 1. The impedance is automatically matched by moving the slug 54, allowing microwaves to be supplied with virtually no power reflection. The radiated microwaves propagate as surface waves on the surface of the ceiling wall 20. The electric field of the microwaves excites the gas introduced into the processing vessel 1, forming surface wave plasma in the plasma generation space U directly below the ceiling wall 20 within the processing vessel 1. For example, a SiN film is formed on the substrate W by plasma CVD using this surface wave plasma.

[0036] In the film formation apparatus 100 of this embodiment, the substrate W is placed in a region separate from the plasma generation region, and plasma diffused from the plasma generation region is supplied to the substrate W, essentially resulting in a low electron temperature and high density plasma. Because the plasma electron temperature is controlled to be low, film formation can be performed without damaging the film to be formed or the elements on the substrate W, and the high density plasma allows for the production of high quality films. Furthermore, since the higher the film formation temperature, the better the film quality. In the case of a SiN film, a higher quality film can be formed by setting the film formation temperature to a high temperature of 500°C or higher as described above.

[0037] After a film such as a SiN film is formed in this manner, the substrate W is unloaded from the processing vessel 1. When performing film formation processing on a plurality of substrates W, the above operations are repeated. By performing such processing on a predetermined number of substrates W, the film formation process of step ST2 is completed.

[0038] After the film formation process of step ST2 as described above, a cleaning process of step ST3 is carried out. After the film formation process of step ST2, deposits 201 of the same components as the pre-coat film 202 and the film 200 formed on the substrate W are deposited inside the processing vessel 1, as shown in Fig. 4. If the next film formation is carried out in this state, these deposits may cause particles, etc., so a cleaning process is carried out to remove these deposits.

[0039] The cleaning process of step ST3 is performed using a fluorine-containing gas. For example, radicals or ions of NF3 gas excited by plasma can be used as the fluorine-containing gas. The plasma may be generated using the plasma source 2 of the film forming apparatus 100, or may be generated using another plasma source, such as a remote plasma source. NF3 gas is supplied into the processing chamber 1 from the gas supply mechanism 3. NF3 gas may be diluted with Ar gas or He gas. Furthermore, chlorine (Cl2) gas, O2 gas, N2 gas, hydrogen bromide (HBr) gas, carbon tetrafluoride (CF4) gas, or the like may be added to adjust the cleaning rate. NF3 gas excited by plasma is preferably used, for example, when the film to be formed on the substrate W is a Si-containing film, such as a SiN film.

[0040] The fluorine-containing gas used for cleaning may be gases other than NF3 gas, such as F2 gas, CF-based gas, or ClF3 gas. The other fluorine-containing gases may not be excited by plasma and may be diluted with Ar gas or He gas. Furthermore, 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 inside the processing chamber 1.

[0041] In the cleaning process, if the temperature of the mounting table 11 is high, a reaction occurs between the fluorine-containing gas used as the cleaning gas and the Al-containing material such as AlN that constitutes the mounting table 11. If the cover member 140 is not used, this reaction can cause the problem shown in FIG. 5. First, as shown in FIG. 5(a), aluminum fluoride (AlF), typically aluminum trifluoride (AlF), can be unintentionally deposited on the surface of the mounting table 11. x For example, when NF3 gas excited by plasma is used, it is highly reactive and AlF x The higher the temperature, the more the fluorination reaction proceeds, and AlF x After the cleaning process, the inside of the processing chamber 1 is maintained at a high vacuum, so that the amount of AlF generated on the surface of the mounting table 11 increases. x is easily sublimated.

[0042] Figure 6 shows the theoretical vapor pressure curve for AlF3, a typical aluminum fluoride. Vapor pressure has a correlation with temperature, and AlF3 becomes a solid at pressures above the vapor pressure curve and a gas at pressures below the vapor pressure curve. As shown in Figure 6, for example, at 600°C, the vapor pressure of AlF3 is 2.4 x 10 -3 Pa, which is higher than the controlled pressure set near the ultimate vacuum in the processing chamber 1 for plasma CVD. Therefore, when the processing chamber 1 is evacuated to the controlled pressure, the AlF3 easily sublimes. x The AlF diffuses from the surface of the mounting table 11 and adheres to and accumulates on the inner surface of the processing vessel 1, which has a low temperature, for example, on the surface of the ceiling wall 20, as shown in FIG. 5(b). x If AlF adheres or accumulates on the inner surface of the processing vessel 1, it becomes difficult to form a stable and uniform film during film formation due to changes in the plasma state, and the thickness of the formed film shifts. x When a film formation process is performed with AlF attached and deposited, as shown in Figure 5(c), x dissociates and gets mixed into the film 300 as contaminants 301 during film formation, causing problems such as deterioration of the properties of the film 300 and defects. x These particles 302 fall into the film and onto the film surface, causing adverse effects.

[0043] Therefore, in this embodiment, a cover member 140 is provided to cover the portion of the mounting table 11 other than the substrate mounting surface, and the sublimated AlF x Adsorbs.

[0044] Even when the cover member 140 is present, as shown in FIG. 7, AlF x At this time, the pressure inside the processing vessel 1 during cleaning is increased by AlF x It is preferable to keep the pressure high enough to prevent sublimation (for example, 133 Pa).

[0045] After the cleaning process in step ST3, the pre-coating process in step ST1 is performed. As a result, AlF 4 present on the upper surface (substrate mounting surface) of the mounting table 11 is removed, as shown in FIG. x The pre-coated film 401 shields the AlF x In this case, the pre-coating process is performed continuously after the cleaning process without any other process, so that the AlF x This makes it possible to more effectively suppress the sublimation of the

[0046] However, it is difficult to form a precoat film on the back surface and side surfaces of the mounting table 11 and the side surfaces of the support member 12, which are hidden by the surface of the mounting table 11. Therefore, the AlF x Therefore, when the vacuum is drawn after pre-coating and the controlled pressure is maintained, the AlF formed on the back surface and side surfaces of the mounting table 11, the side surfaces of the support member 12, etc. x is sublimated.

[0047] In contrast, in this embodiment, the cover member 140 is provided, and therefore, as shown in FIG. 9, the AlF x Even if sublimated, the sublimated AlF x is adsorbed onto the inner surface of the cover member 140. Therefore, the sublimated AlF x is prevented from diffusing to the upper side of the processing vessel 1, and the sublimated AlF x This can prevent the sublimated AlF from adhering to the inner surface of the processing vessel 1. x This minimizes the adverse effects of adhesion to the inner surface of the processing vessel, allowing for more stable film formation.

[0048] During the cleaning process in step ST3, it is preferable that the cover member 140 be at a temperature lower than that of the mounting table 11. When the cover member is at a lower temperature than that of the mounting table 11, the thermophoresis effect occurs, and AlF xis easily adsorbed to the low-temperature cover member 140. As the temperature of the cover member 140 decreases, the adsorbed AlF x The sublimation of AlF is suppressed, and the sublimated AlF x This can effectively prevent the harmful effects caused by adhesion to the inner surface of the processing vessel 1. The temperature of the cover member 140 is preferably 300° C. or less.

[0049] In this example, the cover member 140 is provided at a distance from the mounting table 11, and therefore the cover member 140 is thermally insulated from the high-temperature mounting table 11, and the cover member 140 can be easily cooled. In order to cool the cover member 140, a temperature control mechanism such as a chiller may be provided on the cover member 140 to control the temperature to a lower temperature than the mounting table 11.

[0050] AlF x In order to further suppress the adverse effects of the sublimation of aluminum fluoride (AlF ) from the mounting table 11, the temperature of the mounting table 11 is also lowered in the cleaning process of step ST3. x Specifically, it is preferable to suppress the sublimation of AlF x It is preferable to control the temperature so that the vapor pressure of AlF3 is lower than the controlled pressure near the ultimate vacuum of the processing chamber 1. For example, in the case of AlF3, the temperature of the mounting table 11 is controlled to a temperature so that the controlled pressure near the ultimate vacuum in the processing chamber 1 is higher than the vapor pressure curve of AlF3 shown in FIG. 6. In the case of a film formation process using plasma CVD as in this embodiment, the ultimate vacuum is 1×10 -3 ~1×10 -4 6, if the pressure is in this range, sublimation of AlF3 can be suppressed by setting the temperature of the mounting table 11 to 500°C or less. The temperature of the mounting table 11 at this time is preferably lower than the temperature of the mounting table 11 during the film formation process in step ST2. x To effectively suppress the sublimation of AlF x It is advantageous for the vapor pressure of the gas to be lower than the ultimate vacuum of the processing chamber 1, and in consideration of this, it is more preferable to set the temperature of the mounting table 11 to 450° C. or lower.

[0051] Lowering the cleaning temperature is also effective in lowering the reaction temperature of the fluoride reaction between the AlN of the mounting table 11 and the fluorine-containing gas (NF3 gas) used as the cleaning gas, and reduces the amount of aluminum fluoride (AlF x ) itself can also be reduced.

[0052] In the cleaning process of step ST3, the pressure inside the processing vessel 1 when cleaning is actually performed by supplying a cleaning gas can be set depending on the volume of the processing vessel 1 and, if plasma is used, the spreading of the plasma used in cleaning. As described above, the pressure during cleaning is set according to the pressure of the formed AlF x It is preferable to make the pressure high enough to create a state where the liquid is difficult to sublimate, and the pressure is preferably 266 Pa or higher.

[0053] As described above, it is preferable to perform the pre-coating step in the next step ST1 consecutively after the cleaning step in step ST3, and in this case, it is desirable to set the pressure inside the processing chamber 1 to a low pressure of, for example, 100 Pa or less so that the pre-coating film is preferentially formed on the surface of the mounting table 11. Furthermore, when the pre-coating step in the next step ST1 is performed after the cleaning step in step ST3, similarly to the cleaning step, the temperature of the mounting table 11 is preferably lower than the temperature of the mounting table 11 during the film formation step in step ST2, and more preferably 450° C. or less.

[0054] In the cleaning process of step ST3, it is preferable to place a dummy substrate dW on the stage 11 as shown in FIG. x By using the dummy substrate dW in this way, it is possible to prevent the reaction that forms AlF xSince the formation of SiF itself is suppressed, there is no need to perform pre-coating consecutively after cleaning. When a Si wafer is used as the dummy substrate dW, SiF gas is formed by reacting with NF gas, but SiF is easily volatilized and is removed from the processing chamber 1 via the exhaust system.

[0055] Furthermore, between the pre-coating step ST1 and the film-forming step ST2, a period of time may be provided in which the processing chamber 1 is evacuated by the exhaust device 16 without supplying gas from the gas supply mechanism 3, and the inside of the processing chamber 1 is maintained in a vacuum state. By maintaining the vacuum state, AlF x is sublimated and adsorbed onto the cover member 140, so that the AlF x The effect of AlF x Contamination reduction and AlF x It is possible to suppress particles.

[0056] As described above, in this embodiment, AlF sublimated from the mounting table 11 x By adsorbing the sublimated AlF x Furthermore, the cleaning process in step ST3 and the pre-coating process in step ST1 are performed at a low temperature, for example, 450° C., and then the temperature of the mounting table 11 is raised to a high temperature, for example, about 600° C., and the film forming process in the next step ST2 is performed. x When the temperature of the mounting table 11 is increased or decreased, it is preferable to suppress the sublimation of AlF x Since the precoat film is formed so as to shield the heat, it is preferable to control the temperature rise and fall so that the precoat film does not peel off.

[0057] Next, the cover member 140 will be described in more detail. The cover member 140 has the above-described structure and is configured to cover the AlF sublimated from the stage 11. xFrom the viewpoint of fulfilling such a function, the material is not particularly limited, and the same aluminum-containing material as the mounting table 11, for example, Al-containing ceramics such as AlN and Al2O3, or Al or an Al alloy, can be used. Other materials that can be used include Ni alloys such as Inconel and Hastelloy, and Fe alloys such as stainless steel.

[0058] Furthermore, at least the surface of the cover member 140 may be made of a material that is more susceptible to fluorination than the Al-containing material that constitutes the mounting table 11, i.e., a material with a lower free energy for forming fluorides. This allows the fluorination reaction to occur preferentially on the surface of the cover member 140 when a fluorine-containing gas such as NF3 gas is supplied in the cleaning process of step ST3, thereby forming fluorides that are easily volatilized, and thus reducing the amount of AlF on the surface of the mounting table 11. x The formation of SiF4 can be suppressed. The formed fluoride can be volatilized and discharged from the processing vessel 1 by the exhaust system, and does not remain in the processing vessel 1. Examples of materials that have a lower free energy of fluoride formation than Al and are easily fluorinated include Si-containing materials such as SiN, SiO2, SiCN, and SiON. These react with fluorine-containing gases such as NF3 gas to form SiF4 at cleaning temperatures. As described above, SiF4 is easily volatilized and is discharged from the processing vessel 1 by the exhaust system, and does not remain in the processing vessel 1 and adversely affect the film formation process.

[0059] For example, the Gibbs free energy of fluoride formation at 550 °C is -213 Kcal / mol for the reaction of AlN to AlF3, while it is -950 Kcal / mol and -510 Kcal / mol for the reactions of SiN to SiF4 and SiO2 to SiF4, respectively.

[0060] In this example, it is sufficient that at least the surface of the cover member 140 is made of a material that is more susceptible to fluorination than the Al-containing substance that constitutes the mounting table 11, and the entire cover member 140 may be made of such a material, or a film of such a material may be formed on the surface of another material.

[0061] Furthermore, at least the surface of the cover member 140 may be made of a material that is less likely to react with the fluorine-containing gas supplied as the cleaning gas. Examples of such materials include stable fluorides such as YF3, NiF, and TaF. YF3, NiF, TaF, and the like have lower vapor pressures than AlF and are less likely to sublimate. FIG. 11 compares the vapor pressure curve of YF3 with that of AlF3, taking the example of YF3. This figure reveals that YF3 has a vapor pressure ten orders of magnitude lower than AlF3 and is less likely to sublimate. The same is true for NiF and TaF. Thus, because YF3 and the like have low vapor pressures, are less likely to sublimate, and are already fluorides, fluorination reactions caused by the fluorine-containing gas can be prevented.

[0062] If the cover member 140 is made of an Al-containing material, the temperature during cleaning may increase, resulting in AlF x , which may cause adverse effects inside the processing vessel 1. Furthermore, if the cover member 140 is made of other substances that react with the fluorine-containing gas, fluoride may remain inside the processing vessel 1. In contrast, if at least the surface of the cover member 140 is made of a material that does not easily react with the fluorine-containing gas, such as YF3, NiF, or TaF, it will hardly react with the fluorine-containing gas even when the temperature during cleaning is high, and AlF x Therefore, AlF x Problems caused by the like sublimating and adhering to the inner surface of the processing vessel 1 are unlikely to occur.

[0063] In this example, it is sufficient that at least the surface of the cover member 140 is made of a material that is difficult to react with the fluorine-containing gas, and the entire cover member 140 may be made of such a material, or a film of such a material may be formed on the surface of another material.

[0064] The cover member 140 may be detachable. By making the cover member 140 detachable, AlF x The cover member 140 that has trapped the particles can be removed and washed, improving maintainability.

[0065] Next, another embodiment of the cover member will be described. 12 is a cross-sectional view showing a schematic configuration of a film forming apparatus using a cover member of another example. The cover member 141 of this example has a configuration in which it is suspended from the outer periphery of the mounting table 11. Specifically, the cover member 141 has a cylindrical portion 141a and an annular portion 141b extending from the upper end of the cylindrical portion 141a to the outer periphery of the mounting table 11, and the annular portion 141b is configured to be supported by the outer periphery of the mounting table 11. The cover member 141 having such a configuration can be easily attached and detached, and maintenance can be further improved. In addition, since there is no gap between the mounting table 11 and the cover member 141, sublimated AlF x In this example, since the cover member 141 is in contact with the mounting table 11, it is more difficult to lower the temperature than the cover member 140, but since the contact portion is the outer periphery of the mounting table 11, heat transfer from the mounting table 11 is limited, and it is possible to achieve a desired temperature reduction.

[0066] 13 is a cross-sectional view showing a schematic configuration of a film forming apparatus using a cover member of yet another example. The cover member 142 of this example has a cylindrical portion 142a provided at a position outside the side surface of the mounting table 11, a first annular portion 142b extending from the upper end of the cylindrical portion 142a toward the mounting table 11, and a second annular portion 142c provided in multiple steps and extending from a position lower than the annular portion 142b of the cylindrical portion 142a. The second annular portion 142c may be a single step. By providing the first annular portion 142b and the second annular portion 142c in multiple steps, AlF x The adsorption area of ​​AlF can be increased. x As shown in FIG. 14, by tilting the first annular portion 142b and the second annular portion 142c upward toward the stage 11, AlF xThis makes it easier to adsorb.

[0067] Although the embodiments have been described above, the disclosed embodiments should be considered to be illustrative and not restrictive in all respects. The above embodiments may be omitted, substituted, or modified in various ways without departing from the scope and spirit of the appended claims.

[0068] For example, in the above embodiment, the film formation apparatus for performing the film formation process is exemplified as one that forms a film using surface wave plasma generated by radiating microwaves into a processing vessel from multiple microwave introduction parts, but this is not limited to this. There may be only one microwave introduction part, and the plasma process is not limited to one that generates plasma by radiating microwaves, but may use various other plasmas, such as capacitively coupled plasma (CCP), inductively coupled plasma (ICP), and electron cyclotron resonance (ECR) plasma. Furthermore, the film formation apparatus may be a thermal CVD apparatus that does not use plasma.

[0069] In the above embodiment, a Si-containing film such as a SiN film is mainly used as an example of the film to be deposited. However, as described above, other films such as a Ti-based film or a carbon film may also be used. Furthermore, in the above embodiment, an example was shown in which NF gas was excited by plasma as the cleaning gas. However, as described above, other fluorine-containing gases such as F gas, CF gas, and ClF gas may also be used. An appropriate cleaning gas can be used depending on the film to be deposited. For example, NF gas excited by plasma can be suitably used for a Si-containing gas such as SiN, F gas or ClF gas can be suitably used for a Ti-based film, and CF gas such as CF gas can be suitably used for a carbon film. [Explanation of symbols]

[0070] 1; Processing container 2. Plasma source 3. Gas supply mechanism 4; Control unit 11;Placement table 20;Ceiling wall 30: Microwave output section 40: Microwave transmission section 50: Microwave radiation mechanism 100; Film deposition equipment 140, 141, 142; Cover member 140a, 141a, 142a; cylindrical portion 140b, 141b, 142b; annular part 142c; Second annulus 300; Film on substrate 401; Pre-coated film W; substrate

Claims

1. A processing vessel; a mounting table containing aluminum and provided in the processing chamber, on which a substrate is placed; a heating mechanism for heating the mounting table; a gas supply mechanism for supplying a film-forming gas and a fluorine-containing gas for cleaning into the processing chamber; a cover member provided to cover a portion of the mounting table other than the substrate mounting surface; and the cover member has a cylindrical portion provided to cover a side surface of the mounting table, and an annular portion extending from the cylindrical portion toward the mounting table, The annular portion is provided in multiple stages, the cover member adsorbs aluminum fluoride that is produced by a reaction between aluminum of the mounting table and the fluorine-containing gas and that sublimes in the processing vessel when the film-forming gas is supplied into the processing vessel to form a film on the substrate, and then the fluorine-containing gas is supplied into the processing vessel to clean the inside of the processing vessel.

2. 2. The film forming apparatus according to claim 1, wherein the mounting table is supported by a support member extending from a bottom of the processing chamber, and the cylindrical portion is provided so as to cover a side surface of the mounting table and the support member.

3. 3. The film forming apparatus according to claim 1, wherein the cover member is maintained at a temperature lower than that of the stage.

4. The film forming apparatus according to claim 3 , wherein the cover member is provided at a distance from the stage.

5. The film forming apparatus according to claim 3 , wherein the cover member is suspended from an outer periphery of the stage.

6. A processing vessel; a mounting table containing aluminum and provided in the processing chamber, on which a substrate is placed; a heating mechanism for heating the mounting table; a gas supply mechanism for supplying a film-forming gas and a fluorine-containing gas for cleaning into the processing chamber; a cover member provided to cover a portion of the mounting table other than the substrate mounting surface; and the cover member is maintained at a lower temperature than the stage and is suspended from the outer periphery of the stage; the cover member adsorbs aluminum fluoride that is produced by a reaction between aluminum of the mounting table and the fluorine-containing gas and that sublimes in the processing vessel when the film-forming gas is supplied into the processing vessel to form a film on the substrate, and then the fluorine-containing gas is supplied into the processing vessel to clean the inside of the processing vessel.

7. 7. The film forming apparatus according to claim 3, wherein the cover member has a temperature regulator that controls the temperature of the cover member to be lower than that of the mounting table.

8. 8. The film deposition apparatus according to claim 1, wherein at least a surface of the cover member is made of a material that is more easily fluoridated than the aluminum-containing material contained in the mounting table.

9. At least the surface of the cover member is made of SiN, SiO ２ 9. The film forming apparatus according to claim 8, wherein the film forming apparatus is made of any one of SiCN and SiON.

10. At least the surface of the cover member is YF ３ 8. The film forming apparatus according to claim 1, wherein the film forming apparatus is made of one of NiF, NiF, and TaF.

11. A processing vessel; a mounting table containing aluminum and provided in the processing chamber, on which a substrate is placed; a heating mechanism for heating the mounting table; a gas supply mechanism for supplying a film-forming gas and a fluorine-containing gas for cleaning into the processing chamber; a cover member provided to cover a portion of the mounting table other than the substrate mounting surface; and At least the surface of the cover member is made of any one of YF 3 , NiF, and TaF; the cover member adsorbs aluminum fluoride that is produced by a reaction between aluminum of the mounting table and the fluorine-containing gas and that sublimes in the processing vessel when the film-forming gas is supplied into the processing vessel to form a film on the substrate, and then the fluorine-containing gas is supplied into the processing vessel to clean the inside of the processing vessel.

12. The fluorine-containing gas is NF excited by plasma. ３ The film forming apparatus according to claim 1 , wherein the gas is a gas.

13. The film forming apparatus according to claim 1 , wherein the mounting table includes AlN.

14. A film formation method for forming a film on a substrate using a film formation apparatus having a processing vessel, a mounting table containing aluminum on which a substrate is placed in the processing vessel, and a cover member provided to cover a portion of the mounting table other than a substrate mounting surface, the method comprising: performing precoating in a state where the substrate is not present in the processing chamber so that a precoat film is formed on at least the surface of the mounting table; supplying a film-forming gas into the processing chamber while heating the substrate on the mounting table, thereby forming a film on one substrate or on multiple substrates consecutively; cleaning the inside of the processing vessel with a fluorine-containing gas while the substrate is removed from the processing vessel; Repeatedly, During the cleaning step, aluminum fluoride is formed on the surface of the mounting table due to a reaction between aluminum in the mounting table and the fluorine-containing gas, and the aluminum fluoride sublimated from the surface of the mounting table is adsorbed onto the cover member, The film forming method further comprises maintaining a pressure in the processing vessel during the cleaning step high enough to prevent the aluminum fluoride from sublimating.

15. The film forming method according to claim 14 , wherein the temperature of the cover member is set lower than the temperature of the stage during the cleaning step.

16. 16. The film forming method according to claim 14, wherein the pre-coating step is performed immediately after the cleaning step, and the aluminum fluoride adsorbed onto the substrate mounting surface on the upper surface of the mounting table is shielded by the pre-coating film formed during the pre-coating step, and aluminum fluoride sublimated from portions of the mounting table other than the substrate mounting surface is adsorbed onto the cover member.

17. 17. The film forming method according to claim 14, wherein the cleaning step is performed in a state where a dummy substrate is placed on the substrate placement surface of the placement table.

18. 18. The film forming method according to claim 14, wherein the film forming step forms a SiN film and is performed by setting the temperature of the mounting table to 500° C. or higher, and the cleaning step and the pre-coating step are performed by setting the temperature of the mounting table to a lower temperature than that of the film forming step.

19. 19. The film forming method according to claim 14, wherein the cleaning step and the pre-coating step are performed by setting the temperature of the mounting table to a temperature at which a vapor pressure of the aluminum fluoride is lower than a controlled pressure in the processing chamber.

20. The fluorine-containing gas is NF excited by plasma. ３ The film forming method according to claim 14 , wherein the gas is a gas.

21. The film forming method according to claim 14 , wherein the mounting table includes AlN.

Images