Film formation method and film formation apparatus

Abstract

To provide a deposition method capable of suppressing an influence on deposition of an aluminum fluoride generated by a reaction between a fluorine-containing gas, which is a cleaning gas, and a placement table containing aluminum when cleaning the inside of a processing container with the fluorine-containing gas after deposition processing.SOLUTION: A deposition method repeatedly performs the steps of: continuously forming a film for one substrate or a plurality of substrates by supplying a deposition gas into a processing container while heating a substrate on a placement table; setting a temperature of the placement table to a temperature at which a vapor pressure of an aluminum fluoride becomes lower than a management pressure in the processing container and cleaning the inside of the processing container with a fluorine-containing gas with the substrate carried out from the processing container; and setting a temperature of the placement table to a temperature at which a vapor pressure of an aluminum fluoride becomes lower than a management pressure in the processing container and performing precoating so that a precoat film is formed on a surface of at least the placement table continuously with the cleaning step.SELECTED DRAWING: Figure 3

Description

Technical Field

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

Background Art

[0002] Patent Document 1 describes that in a microwave plasma processing apparatus, after performing a film forming process or the like in a processing container, the inside of the processing container is cleaned using NF3 gas excited by plasma.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present disclosure provides a film forming method and a film forming apparatus capable of suppressing the influence on the film formation of aluminum fluoride generated by the reaction between a fluorine - containing gas as a cleaning gas and a mounting table containing aluminum during the cleaning of the inside of a processing container with the fluorine - containing gas after a film forming process.

Means for Solving the Problems

[0005] A film forming method according to an aspect of the present disclosure is a film forming method for forming a film on a substrate by a film forming apparatus having a processing container and a mounting table containing aluminum on which the substrate is placed inside the processing container, the method including: supplying a film forming gas into the processing container while heating the substrate on the mounting table to form a film continuously on one substrate or a plurality of substrates; and with the substrate removed from the processing container, setting the temperature of the mounting table such that the vapor pressure of aluminum fluoride is within the processing container Set near the ultimate vacuumThe step of cleaning the inside of the processing vessel with a fluorine-containing gas at a temperature lower than the management pressure, and the temperature of the mounting table is such that the vapor pressure of aluminum fluoride is within the processing vessel The one set near the ultimate vacuum The step of performing precoating so that a precoat film is formed at least on the surface of the mounting table, continuously with the cleaning step, at a temperature lower than the management pressure, is repeated Yes, the step of forming the film is carried out with the temperature of the mounting table at 500°C or higher, and the cleaning step and the pre-coating step are carried out with the temperature of the mounting table at 450°C or lower. .

Advantages of the Invention

[0006] According to the present disclosure, when cleaning the inside of the processing vessel with a fluorine-containing gas after the film-forming process, it is possible to suppress the influence on the film formation of aluminum fluoride generated by the reaction between the fluorine-containing gas, which is the cleaning gas, and the mounting table containing aluminum. A film-forming method and a film-forming apparatus are provided.

Brief Description of the Drawings

[0007]

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Embodiments for Carrying Out the Invention

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

[0009] <Film formation apparatus> FIG. 1 is a cross-sectional view showing an example of a film formation apparatus for carrying out a film formation method according to an embodiment, and FIG. 2 is a cross-sectional view showing an A-A cross-section of the film formation apparatus of FIG. 1.

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

[0011] The film formation apparatus 100 has a processing vessel (chamber) 1 that houses a substrate W. The film formation apparatus 100 performs a film formation process on the substrate W by surface wave plasma formed in the vicinity of the inner wall surface of the top wall portion in 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 examples thereof include Si-containing films such as silicon nitride films (SiN films). Note that the substrate W is exemplified by a semiconductor wafer, but is not limited to a semiconductor wafer, and may be other substrates such as an FPD substrate or a ceramics substrate.

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

[0013] The processing chamber 1 includes a substantially cylindrical container body 10 with an open upper portion and a top wall portion 20 that closes the upper opening of the container body 10, and a plasma processing space is formed inside. 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 disc shape. A seal ring 129 is interposed between the contact surfaces of the container body 10 and the top wall portion 20, whereby the inside of the processing chamber 1 is hermetically sealed.

[0014] A mounting table 11 for mounting the substrate W is horizontally provided in the processing chamber 1 and is supported by a cylindrical support member 12 erected at the center of the bottom of the processing chamber 1. The mounting table 11 is made of a substance containing aluminum (Al), for example, aluminum nitride (AlN) which is an insulating ceramic. Also, the material constituting the mounting table 11 may be alumina (Al2O3) which is also an insulating ceramic containing Al. The support member 12 may be metal or ceramic. When the support member 12 is metal, an insulating member 12a is interposed between the support member 12 and the bottom of the processing chamber 1. A heater 13 is provided in the mounting table 11, and a heater power supply 14 is connected to the heater 13. By supplying power from the heater power supply 14 to the heater 13, the mounting table 11 is heated to an arbitrary temperature up to, for example, 700°C. Three elevating pins (not shown) for elevating the substrate W are provided on the mounting table 11, and the substrate W is transferred in a state where the elevating pins protrude from the surface of the mounting table 11. Note that the mounting table 11 may be provided with an electrostatic chuck for electrostatically adsorbing the substrate W, a gas flow path for supplying a gas for heat transfer to the back surface of the substrate W, etc. Also, an electrode may be provided on the mounting table 11, and a high-frequency bias for attracting ions in the plasma may be applied to the electrode.

[0015] 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, whereby the inside of the processing container 1 is rapidly decompressed to a predetermined degree of vacuum. An inlet / outlet 17 for loading and unloading the substrate W and a gate valve 18 for opening and closing the inlet / outlet 17 are provided on the side wall of the processing container 1.

[0016] 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 unit 30, a microwave transmission unit 40, and a microwave radiation mechanism 50.

[0017] The microwave output unit 30 includes a microwave power source, a microwave oscillator for oscillating microwaves, an amplifier for amplifying the oscillated microwaves, and a distributor for distributing the amplified microwaves into a plurality. Then, the microwaves are distributed into a plurality and output.

[0018] The microwaves output from the microwave output unit 30 are radiated into the processing container 1 through the microwave transmission unit 40 and the microwave radiation mechanism 50. Further, as will be described later, gas is supplied into the processing container 1, and the supplied gas is excited by the introduced microwaves to form surface wave plasma.

[0019] The microwave transmission unit 40 transmits the microwaves output from the microwave output unit 30. The microwave transmission unit 40 includes a plurality of amplifier units 42, a central microwave introduction unit 43a disposed at the center of the ceiling wall unit 20, and six peripheral microwave introduction units 43b disposed at equal intervals on the peripheral edge of the ceiling 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 each of the central microwave introduction unit 43a and the six peripheral microwave introduction units 43b. The central microwave introduction unit 43a and the six peripheral microwave introduction units 43b have functions of introducing the microwaves output from the amplifier units 42 provided corresponding to each of them into the microwave radiation mechanism 50 and matching the impedance.

[0020] The central microwave introduction unit 43a and the peripheral microwave introduction units 43b are configured by coaxially arranging a cylindrical outer conductor 52 and a rod-shaped inner conductor 53 provided at the center thereof. Between the outer conductor 52 and the inner conductor 53, microwave power is supplied, and it serves as a microwave transmission path 44 through which microwaves propagate toward the microwave radiation mechanism 50.

[0021] The central microwave introduction unit 43a and the peripheral microwave introduction units 43b are provided with a pair of slugs 54 and an impedance adjustment member 140 located at the tip thereof. By moving the slugs 54, the impedance of the load (plasma) in the processing container 1 is matched with the characteristic impedance of the microwave power source in the microwave output unit 30. The impedance adjustment member 140 is formed of a dielectric and adjusts the impedance of the microwave transmission path 44 according to its relative permittivity.

[0022] 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 at positions corresponding to the peripheral microwave introduction portion 43b on the upper surface of the top wall portion 20, respectively. Also, the dielectric members 123 and 133 are provided at positions corresponding to the central microwave introduction portion 43a inside the top wall portion 20 and at the peripheral microwave introduction portion 43b, respectively. The slots 122 and 132 are provided in portions between the slow-wave material 121 and the dielectric member 123 of the top wall portion 20 and in portions between the slow-wave material 131 and the dielectric member 133 of the top wall portion 20, respectively, and the portions where these slots are formed become the slot antennas 124 and 134.

[0023] The slow-wave materials 121 and 131 are disk-shaped, arranged so as to surround the tip portions of the inner conductor 53, have a dielectric constant larger than that of a vacuum, and are made of, for example, fluororesins such as quartz, ceramics, polytetrafluoroethylene, or polyimide resins. The slow-wave materials 121 and 131 have a function of shortening the wavelength of microwaves compared to that in a vacuum to make the antenna smaller. The slow-wave materials 121 and 131 can adjust the phase of microwaves according to their thicknesses, and the thicknesses are adjusted so that the slot antennas 124 and 134 become the "bellies" of standing waves, minimizing reflection and maximizing the radiation energy of the slot antennas 124 and 134.

[0024] The dielectric members 123 and 133 are formed of, for example, quartz, ceramics such as alumina (Al2O3), fluororesins such as polytetrafluoroethylene, or polyimide resins, similar to the slow-wave materials 121 and 131. The dielectric members 123 and 133 are fitted into the spaces formed inside the top wall portion 20, and concave window portions 21 are formed in portions of the lower surface of the top wall portion 20 corresponding to the dielectric members 123 and 133. Therefore, the dielectric members 123 and 133 are exposed in the processing vessel 1 and function as dielectric windows for supplying microwaves to the plasma generation space U.

[0025] Note that the number of the peripheral microwave introduction parts 43b and the dielectric members 133 is not limited to six, and may be two or more, but three or more is preferable.

[0026] As will be described later, the gas supply mechanism 3 supplies a gas for film formation, a gas for cleaning, and a gas for plasma treatment after cleaning into the processing container 1. The gas supply mechanism 3 includes 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 top wall portion 20, and a gas discharge port 64 that discharges the gas from the gas flow path 63. A plurality of gas discharge ports 64 are provided around the dielectric members 123 and 133 of the window portion 21 of the top wall portion 20 (see FIG. 2). Note that the gas supply mechanism 3 is not limited to discharging gas from the top wall portion 20 as in this example.

[0027] The control unit 4 controls the operations and processes of each component of the film forming apparatus 100, for example, the gas supply of the gas supply mechanism 3, the frequency 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 has a CPU (Central Processing Unit), a RAM, and a 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 uses the RAM as a work area and executes a program such as a processing recipe stored in the ROM or the storage medium of the storage device to control the film forming apparatus 100.

[0028] <Film Forming Method> Next, a film forming method in the film forming apparatus 100 configured as described above will be described. FIG. 3 is a flowchart showing a film forming method according to an embodiment.

[0029] As shown in FIG. 3, in this embodiment, steps ST1, ST2, and ST3 are repeatedly performed. In step ST1, while heating the substrate W on the mounting table 11 containing Al, a film-forming gas is supplied into the processing container 1 to continuously form a film on one substrate W or a plurality of substrates W. In step ST2, with the substrate W carried out from the processing container 1, the temperature of the mounting table 11 is set to a temperature at which the vapor pressure of aluminum fluoride is lower than the control pressure in the processing container 1, and the inside of the processing container 1 is cleaned with a fluorine-containing gas. In step ST3, similar to step ST2, the temperature of the mounting table 11 is set to a temperature at which the vapor pressure of aluminum fluoride is lower than the control pressure in the processing container 1, and pre-coating is performed so that a pre-coat film is formed at least on the surface of the mounting table continuously with the cleaning step.

[0030] In the film-forming step of step ST1, film formation is continuously performed on one substrate W or a plurality of substrates W in a state where the pre-coating treatment of step ST3 described later is performed in the processing container 1. Examples of the plurality of substrates W include up to about 100 substrates. The film to be formed is not particularly limited, but a silicon (Si)-containing film, for example, a SiN film is exemplified as a suitable example. Other Si-containing films such as a SiCN film, a SiO2 film, and a SiON film may also be used.

[0031] When forming a SiN film, as the film-forming gas, a Si-containing gas and a nitrogen-containing gas can be used. As the Si-containing gas, for example, silane-based compound gases such as monosilane (SiH4) gas, disilane (Si2H6) gas, and trimethylsilane (SiH(CH3)3) gas can be used. As the nitrogen-containing gas, for example, ammonia (NH3) gas, nitrogen (N2) gas, etc. can be used. In the case of a SiCN film, as the film-forming gas, a gas obtained by adding a carbon-containing gas to the above-mentioned Si-containing gas and nitrogen-containing gas can be used. As the carbon-containing gas, hydrocarbon-based gases such as ethylene (C2H4) gas, acetylene (C2H2) gas, ethane (C2H6) gas, propylene (C3H6) gas, and trimethylsilane ((CH3)3SiH) gas can be used. In the case of a SiO2 film, a Si-containing gas and an oxygen-containing gas can be used. As the Si-containing gas, silane-based compound gases as described above can be used. Also, as the oxygen-containing gas, for example, oxygen (O2) gas, nitric oxide (NO) gas, nitrous oxide (N2O) gas, etc. can be used. In the case of a SiON film, as the film-forming gas, a gas obtained by adding the above-mentioned nitrogen-containing gas to the above-mentioned Si-containing gas and oxygen-containing gas can be used. In any case, as other gases, argon (Ar) gas and helium (He) gas may be used as dilution gases or plasma generation gases.

[0032] 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.

[0033] In the film formation process of step ST1, first, the gate valve 18 is opened, and the substrate W held on a transfer arm (not shown) is carried into the processing vessel 1 from the carry-in outlet 17, placed on the mounting table 11, and the gate valve 18 is 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 above-mentioned SiN film, the temperature of the substrate W is preferably 500°C or higher. More preferably, it is 500 to 650°C. Then, according to the film to be formed, the above-mentioned gas is introduced into the processing vessel 1, the pressure in the processing vessel 1 is controlled, and a film formation process is performed by plasma CVD. The pressure in the processing vessel 1 can be arbitrarily selected according to the distance from the plasma source to the substrate W, the spreading manner of the plasma, the film formation rate, the film thickness to be formed, etc. When the film to be formed is a SiN film, a pressure of 266 Pa or less can be used.

[0034] In generating plasma, while introducing gas into the processing vessel 1, microwaves are output from the microwave output section 30 of the plasma source 2. At this time, the microwaves distributed and output from the microwave output section 30 are amplified by the amplifier section 42 of the microwave transmission section 40, and then transmitted through the central microwave introduction section 43a and the peripheral microwave introduction section 43b. Then, the transmitted microwaves pass 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 of the microwave radiation mechanism 50, and are radiated into the processing vessel 1. At this time, by moving the slag 54, the impedance is automatically matched, and microwaves are supplied in a state where there is substantially no power reflection. The radiated microwaves propagate as surface waves on the surface of the top wall portion 20. The gas introduced into the processing vessel 1 is excited by the electric field of this microwave, and surface wave plasma is formed in the plasma generation space U directly below the top wall portion 20 in the processing vessel 1. For example, a SiN film is formed on the substrate W by plasma CVD using this surface wave plasma.

[0035] In the film forming apparatus 100 of the present embodiment, the substrate W is disposed in a region separated from the plasma generation region, and plasma diffused from the plasma generation region is supplied to the substrate W, so that essentially a plasma with a low electron temperature and a high density is obtained. Since the electron temperature of the plasma is low and controlled, film formation can be performed without damaging the formed film or the elements of the substrate W, and a high-quality film can be obtained by the high-density plasma. Further, since the film quality improves as the film formation temperature increases, when the film to be formed is 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.

[0036] After forming a film such as a SiN film as described above, the substrate W, which is the substrate, is carried out from the processing container 1, and the film formation step of step ST1 is completed.

[0037] After the film formation step of step ST1 as described above, the cleaning step of step ST2 is carried out. In the processing container 1 after the film formation step of step ST1, as shown in FIG. 4, deposits 201 having the same components as the precoat film 202 and the film 200 formed on the substrate W are deposited. If the next film formation is carried out in this deposited state, it will cause particles and the like, so a cleaning step for cleaning and removing these is carried out.

[0038] The cleaning step of step ST2 is carried out using a fluorine-containing gas. As the fluorine-containing gas, for example, radicals or ions of NF3 gas excited by plasma can be used. The plasma at this time may be generated using the plasma source 2 of the film forming apparatus 100, or may be generated using another plasma source, for example, a remote plasma. The NF3 gas is supplied from the gas supply mechanism 3 into the processing container 1. The NF3 gas may be diluted with Ar gas or He gas. Further, for adjusting the cleaning rate, chlorine (Cl2) gas, O2 gas, N2 gas, hydrogen bromide (HBr) gas, carbon tetrafluoride (CF4) gas, etc. may be added. The NF3 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.

[0039] As the fluorine-containing gas used for cleaning, gases other than NF3 gas, such as F2 gas, CF-based gas, ClF3 gas, etc., can also be used. Other fluorine-containing gases do not have 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 according to the material of the film deposited and adhered in the processing vessel 1.

[0040] By the way, in the cleaning process, when the mounting table 11 is at a high temperature, the fluorine-containing gas used as the cleaning gas reacts with an Al-containing substance such as AlN constituting the mounting table 11. As a result, as shown in Fig. 5(a), aluminum fluoride (AlF x ) represented by aluminum trifluoride (AlF3) is unintentionally generated on the surface of the mounting table 11. For example, when using NF3 gas excited by plasma, since it is highly reactive, AlF x is generated at 150 °C or higher. The higher the temperature, the easier the fluorination reaction proceeds, and the larger the amount of AlF x generated. Since the inside of the processing vessel 1 is maintained at a high vacuum, AlF x generated on the surface of the mounting table 11 is likely to sublime.

[0041] Fig. 6 shows the theoretical vapor pressure curve of AlF3, which is a typical aluminum fluoride. The vapor pressure has a correlation with temperature. AlF3 becomes solid at a pressure above the vapor pressure curve and becomes gas at a pressure below the vapor pressure curve. As shown in Fig. 6, for example, at 600 °C, the vapor pressure of AlF3 is 2.4×10 -3 Pa, which is higher than the control pressure set near the achievable vacuum degree in the processing vessel 1 of plasma CVD. Therefore, AlF3 easily sublimes. The sublimated AlF x diffuses from the surface of the mounting table 11 and adheres and deposits on the inner wall of the processing vessel 1 with a lower temperature, for example, the surface of the top wall portion 20 as shown in Fig. 5(b). AlF xWhen it adheres and deposits, due to changes in the plasma state, etc., it becomes difficult to perform stable and uniform film formation during film formation, and a film thickness shift occurs in the formed film. Further, when film formation processing is performed with AlF x adhered and deposited on the inner wall of the processing vessel 1, as shown in FIG. 5(c), AlF x dissociates and is mixed into the film 300 during film formation as contamination 301, deteriorating the characteristics of the film 300 or causing problems such as defects. Furthermore, AlF x becomes particles 302, falls into the film and onto the film surface, and has an adverse effect.

[0042] Therefore, in the present embodiment, in the cleaning step of step ST2, the temperature of the mounting table 11 is lowered to suppress the sublimation of aluminum fluoride (AlF x ). More specifically, the temperature of the mounting table 11 is controlled to a temperature at which the vapor pressure of AlF x is lower than the control pressure near the ultimate vacuum degree of the processing vessel 1. For example, in the case of AlF3, the temperature of the mounting table 11 is controlled to a temperature such that the control pressure near the ultimate vacuum degree in the processing vessel 1 is higher than the vapor pressure curve of AlF3 in FIG. 6. In the case of film formation processing by plasma CVD as in the present embodiment, the ultimate vacuum degree is about 1×10 -3 to 1×10 -4 Pa as shown by the diagonal lines in FIG. 6, and it can be derived that sublimation of AlF3 can be suppressed by setting the temperature of the mounting table 11 to 500°C or lower at this pressure range. 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 step of step ST1. Further, in order to effectively suppress the sublimation of AlF x , it is advantageous for the vapor pressure of AlF x to exist on the lower side with respect to the ultimate vacuum degree of the processing vessel 1. Considering this point, it is more preferable to set the temperature of the mounting table 11 to 450°C or lower.

[0043] Note that lowering the cleaning temperature also has the effect of reducing the reaction temperature of the fluoride reaction between AlN on the mounting table 11 and the fluorine-containing gas (NF3 gas) which is the cleaning gas, and the generated aluminum fluoride (AlFx It also has the effect of reducing the amount of

[0044] In the cleaning step of step ST2, when supplying a cleaning gas and actually performing cleaning, the pressure inside the processing vessel 1 can basically be arbitrarily set according to the volume of the processing vessel 1 and the spreading manner of the plasma used in the case of using plasma. The pressure ranges from 10 to 1000 Pa, and specifically, 400 Pa is exemplified.

[0045] The precoat step of step ST3 is performed after the cleaning step of step ST2 and prior to the next film-forming step. In the precoat step, in a state where the substrate W does not exist in the processing vessel 1, a precoat film containing the film to be formed on the substrate W in the film-forming step or the components of that film is deposited on at least the surface of the mounting table 11 inside the processing vessel 1. At this time, the precoat film is also deposited on the side wall and the ceiling portion 20 surface of the processing vessel 1. As the precoat film, the same material as the film to be formed on the substrate W or a material containing the components of the film to be formed can be used. For example, when the film to be formed is a SiN film, it may be the same SiN film, or other Si-based films such as a SiCN film, a SiON film, or a SiOC film.

[0046] The precoat step of step ST3, similar to the cleaning step of step ST2, controls the temperature of the mounting table 11 to a temperature at which the vapor pressure of aluminum fluoride (AlF x ) is lower than the control pressure inside the processing vessel 1 and is performed continuously with the cleaning step. Also, the temperature of the mounting table 11 during the precoat step of step ST3 is preferably lower than the temperature of the mounting table 11 during the film-forming step of step ST1, and more preferably 450 °C or lower, similar to the case of the cleaning step. Furthermore, it is even more preferable that the temperature of the mounting table 11 during the precoat step of step ST3 is the same as the temperature of the mounting table during the cleaning step of step ST2. By performing the precoat with the mounting table 11 cooled in this way, AlF during the precoat step xIn addition, by performing the pre-coating process immediately after the cleaning process, the sublimation of AlF on the surface of the mounting table 11 can be suppressed as shown in FIG. x Even if any of AlF remains on the surface of the mounting table 11, it can be shielded by the precoat film 401. x Therefore, the AlF 3 on the surface of the mounting table 11 is shielded during the subsequent film formation process and during the film formation process at high temperatures. x In addition, by covering the surface of the mounting table 11 with a precoat film, it is possible to prevent metal contamination from adhering to the rear surface of the substrate W during transportation, which is a problem in the semiconductor manufacturing process.

[0047] Here, performing the pre-coating process "consecutively" after the cleaning process means performing the pre-coating process immediately after the cleaning process without going through any other processes. The pre-coating process may also include a pre-treatment such as a plasma treatment that is performed before depositing the pre-coating film 401.

[0048] The pressure inside the processing chamber 1 during the pre-coating step is desirably set 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 .

[0049] As described above, in this embodiment, as shown in Fig. 8, the cleaning process of step ST2 and the pre-coating process of step ST3 are performed consecutively at a low temperature, for example, 450°C, and then the temperature of the mounting table 11 is increased to a high temperature, for example, about 600°C, and the film forming process of the next step ST1 is performed. After the film forming process, the temperature of the mounting table 11 is decreased to a low temperature, for example, 450°C, and the next cleaning process is performed. When the temperature of the mounting table 11 is increased or decreased, the 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.

[0050] Next, an experiment for confirming the effect of this embodiment will be described. Here, for the following Samples A to C, the amount of Al contamination was measured by the measurement method shown below. Sample A is a sample in which film formation was performed at the same high temperature after cleaning at a high temperature (600 °C), Sample B is a sample in which film formation was performed at a high temperature after cleaning at a low temperature (450 °C), and Sample C is a sample of this embodiment in which cleaning and pre-coating at a low temperature were continuously performed and then film formation was performed at a high temperature. As shown in FIG. 9, the measurement method is to place the sample substrate 502 on the lifting pin 501 protruding from the upper surface of the mounting table 11, and AlF sublimated from the mounting table 11 and adsorbed on the back surface of the sample substrate 502 x was measured by X-ray fluorescence analysis (XRF) as Al contamination. As a result, in Sample A of the conventional method, the amount of Al contamination was as high as 5.0×10 15 (atoms / cm 2 ), and the amount of sublimation of AlF x into the processing container 1 was large. On the other hand, in the case of Sample B in which only the cleaning temperature was lowered, the amount of Al contamination was only slightly reduced to 3.1×10 15 (atoms / cm 2 ), and it was confirmed that the sublimation suppression effect of AlF x was not sufficient. In contrast, in Sample C using the method of this embodiment, the amount of Al contamination was 1.0×10 at the measurement lower limit of the X-ray fluorescence apparatus 12 (atoms / cm 2 ) or less, and it was confirmed that the sublimation of AlF x was reliably suppressed.

[0051] Next, other embodiments will be described. The pressure in the processing container 1 is generally controlled to a low pressure near the ultimate vacuum for leak and residual gas management in the processing container 1 in a state without gas flow. During processing, in addition, pressure control is performed by adjusting the gas flow and the exhaust amount of the exhaust system. In such a pressure management case, for example, when raising the temperature of the mounting table 11 from a low-temperature pre-coating process to a high-temperature film formation process, the vapor pressure of AlF x is higher than the low pressure near the ultimate vacuum, and AlF xSublimation may occur. Therefore, in this embodiment, when raising the temperature of the mounting table 11 from the temperature during the precoat process to the temperature during the film formation process, an inert gas (Ar gas or N2 gas) is flowed to increase the control pressure of the processing chamber 1 as shown in FIG. 10 (pressure control during pressurization). Thereby, while pressurizing the control pressure of the processing chamber 1 to be equal to or higher than the vapor pressure of AlF x it is possible to raise the temperature, thereby further suppressing the sublimation of AlF x existing in the lower layer of the precoat film. That is, in addition to shielding AlF x with the precoat film, it is possible to further suppress the sublimation of AlF x by performing pressure control during pressurization.

[0052] Also, as shown in FIG. 11, not only when raising the temperature from the precoat process to the film formation process, but also when transporting the substrate W during the film formation process performed at a high temperature or when cooling from the high-temperature film formation process to the low-temperature cleaning process, by performing pressure control during pressurization in the same manner, the sublimation suppression effect of AlF x can be further enhanced.

[0053] As the pressure during such pressure control during pressurization, for example, 266 Pa is used. The pressure at this time is preferably such that a greater difference can be taken with respect to the vapor pressure of AlF x in order to suppress the sublimation of AlF x during temperature increase.

[0054] Next, another embodiment will be described. In this embodiment, as shown in FIG. 12, after the precoat process of step ST3 described above, as step ST4, a second precoat is performed under conditions that conform to the film formation conditions of the film to be formed on the substrate W.

[0055] The precoat process at a low temperature in step ST3 suppresses the sublimation of AlF x while AlF xThis is done to shield, and for the precoat film, it is desirable to have precoat conditions that are dense, have a high film density, and a high shielding effect. For example, when forming a SiN film as the precoat film for forming a SiN film, it is desirable for the RI value (refractive index) to be high in order to obtain a high film density. The low-temperature precoat process in step ST3 is suitable for forming a precoat film with such characteristics.

[0056] By the way, when forming a film on the substrate W, due to various requirements on the semiconductor device side, the required characteristics of the film are different. For example, when forming a SiN film on the substrate W, there are requirements such as wanting to form a SiN film with a low RI value and wanting to control the stress value of the formed SiN film. The physical property values of the SiN film are determined by the film formation conditions of the SiN film, but the film quality of the precoat film also has an impact. In order to form a SiN film with desired characteristics on the substrate W, it is preferable that the conditions of the precoat film itself are closer to those of the SiN film to be formed on the substrate W.

[0057] Therefore, in this embodiment, after the low-temperature precoat process in step ST3, a second precoat is performed under conditions that match the film formation conditions of the film to be formed on the substrate W in step ST4. As a result, as shown in FIG. 13, a second precoat film 402 is formed on the first precoat film 401 formed on the surface of the mounting table 11 by the precoat process in step ST3 by the second precoat process in step ST4. The first precoat film 401 on the mounting table 11 side is AlF x is formed under high-density conditions at low temperature to shield, and the second precoat film 402 on the surface side is formed under the same or similar conditions as the film formation conditions when forming a film on the substrate W after being heated to the temperature of the subsequent film formation process in order to adjust the physical property values of the film to be formed on the substrate W. By making the precoat multilayered in this way, it becomes possible to achieve both suppression of the sublimation of AlF x and control of the film quality of the film to be formed on the substrate W.

[0058] Also, as shown in FIG. 14, an intermediate precoat film 403 may be formed between the first precoat film 401 formed by the precoat process in step ST3 and the second precoat film 402 formed by the second precoat process in step ST4. The intermediate precoat film 403 adjusts the stress between the first precoat film 401 and the second precoat film 402 and is used for purposes such as improving the adhesion between these precoat films. By adopting such a structure, it is possible to prevent the peeling of the precoat film and lead to the reduction of particles and the like.

[0059] <Other applications> As described above, the embodiments have been explained. However, the embodiments disclosed this time should be considered as illustrative in all respects and not restrictive. The above embodiments may be omitted, substituted, or changed in various forms without departing from the scope and gist of the appended claims.

[0060] For example, in the above embodiment, as a film forming apparatus for performing film forming treatment, an example is given of a film forming apparatus that uses surface wave plasma generated by radiating microwaves into a processing chamber from a plurality of microwave introduction parts. However, the present invention is not limited to this. The number of microwave introduction parts may be one. Also, the plasma treatment is not limited to a method of generating plasma by radiating microwaves. For example, it may use various other plasmas such as capacitively coupled plasma (CCP), inductively coupled plasma (ICP), and electron cyclotron resonance (ECR) plasma. Furthermore, as the film forming apparatus, thermal CVD or the like that does not use plasma may also be used.

[0061] In the above-described embodiment, a Si-containing film such as a SiN film was mainly exemplified as the film to be formed. However, the present invention is not limited thereto, and as described above, other films such as a Ti-based film and a carbon film may be used. Further, in the above-described embodiment, an example in which NF3 gas as a cleaning gas is excited by plasma was shown. However, as described above, other fluorine-containing gases such as F2 gas, CF-based gas, and ClF3 gas can also be used. The cleaning gas can be appropriately selected according to the film to be formed. For example, in the case of a Si-containing gas such as SiN, NF3 gas excited by plasma can be preferably used. In the case of a Ti-based film, F2 gas or ClF3 gas can be preferably used, and in the case of a carbon film, a CF-based gas such as CF4 gas can be preferably used.

Explanation of Signs

[0062] 1; Processing container 2; Plasma source 3; Gas supply mechanism 4; Control unit 11; Mounting table 20; Ceiling wall part 30; Microwave output part 40; Microwave transmission part 50; Microwave radiation mechanism 100; Film forming apparatus 300; Film on substrate 401; Primer coat film (first primer coat film) 402; Second primer coat film 403; Intermediate primer coat film W; Substrate

Claims

1. A film forming method for forming a film on a substrate by a film forming apparatus having a processing container and a mounting table containing aluminum for mounting the substrate in the processing container, comprising: a step of supplying a film forming gas into the processing container while heating the substrate on the mounting table, and forming a film continuously on one substrate or a plurality of substrates; a step of cleaning the inside of the processing container with a fluorine-containing gas, with the temperature of the mounting table set to a temperature at which the vapor pressure of aluminum fluoride is lower than the control pressure set near the ultimate vacuum degree in the processing container, in a state where the substrate is carried out of the processing container; a step of performing a precoat so that a precoat film is formed at least on the surface of the mounting table, continuously following the cleaning step, with the temperature of the mounting table set to a temperature at which the vapor pressure of aluminum fluoride is lower than the control pressure set near the ultimate vacuum degree in the processing container; repeating the above steps; wherein the step of forming the film is carried out with the temperature of the mounting table at 500 °C or higher; and the cleaning step and the precoat step are carried out with the temperature of the mounting table at 450 °C or lower.

2. The film forming method according to claim 1, wherein the step of forming the film forms a Si-containing film.

3. The film forming method according to claim 2, wherein the Si-containing film is a SiN film.

4. The film forming method according to any one of claims 1 to 3, wherein the step of forming the film is carried out by generating plasma of the film forming gas.

5. The film forming method according to claim 4, wherein the plasma is microwave plasma.

6. The step of cleaning uses NF gas excited by plasma as the fluorine-containing gas ３ The film-forming method according to any one of claims 1 to 5, which uses the gas

7. The film forming method according to any one of claims 1 to 6, wherein the precoat film formed in the step of performing the precoat is made of the same material as the film formed on the substrate or contains components of the film.

8. A film forming method for forming a film on a substrate by a film forming apparatus having a processing container and a mounting table containing aluminum for mounting the substrate in the processing container, comprising: mounting the substrate on the mounting table, supplying a Si-containing gas and a nitrogen-containing gas into the processing container while heating the substrate to 500 °C or higher, generating plasma of these gases, and forming a SiN film continuously on one substrate or a plurality of substrates. With the substrate unloaded from the processing container, the temperature of the mounting table is set to a temperature at which the vapor pressure of aluminum fluoride is lower than the control pressure set near the achievable vacuum level in the processing container, and the inside of the processing container is cleaned with NF gas excited by plasma as a fluorine-containing gas. ３ A step of cleaning the inside of the processing container with the gas; The temperature of the mounting table is set to a temperature at which the vapor pressure of aluminum fluoride becomes lower than the management pressure set near the achieved vacuum degree in the processing chamber, and in a process consecutive to the cleaning process, a precoat is performed such that a precoat film is formed at least on the surface of the mounting table. This is repeated. The cleaning process and the precoat process are performed with the temperature of the mounting table being 450°C or lower, which is a film forming method.

9. The plasma in the step of forming the film is microwave plasma, and the film forming method according to claim 8.

10. The precoat film formed in the step of performing the precoat is the SiN film or another Si-based film formed on the substrate, and the film forming method according to claim 8 or claim 9.

11. The temperature of the mounting table during the cleaning process and the precoat process is the same temperature, and the film forming method according to any one of claims 1 to 10.

12. When performing the step of forming the film following the step of performing the precoat, the temperature of the mounting table is raised, and at that time, an inert gas is introduced into the processing chamber to increase the management pressure, and the film forming method according to any one of claims 1 to 11.

13. The method further includes a step of performing a second precoat under conditions adapted to the film forming conditions of the film to be formed on the substrate after the step of performing the precoat, and the film forming method according to any one of claims 1 to 11.

14. The step of performing the second precoat is carried out at the same temperature as the temperature during the step of forming the film, and the film forming method according to claim 13.

15. The mounting table is made of aluminum nitride, and the film forming method according to any one of claims 1 to 14.

16. A processing chamber, A mounting table provided in the processing chamber and containing aluminum for mounting a substrate, A heating mechanism for heating the mounting table, A gas supply mechanism for supplying gas into the processing chamber, A control unit, A film forming apparatus having, The control unit, While heating the substrate on the mounting table, supplying a film forming gas into the processing chamber to form a film continuously on one substrate or a plurality of substrates. In a state where the substrate is unloaded from the processing container, the temperature of the mounting table is set to a temperature at which the vapor pressure of aluminum fluoride is lower than the control pressure set near the ultimate vacuum degree in the processing container, and the inside of the processing container is cleaned with a fluorine-containing gas. In a state where the temperature of the mounting table is set to a temperature at which the vapor pressure of aluminum fluoride is lower than the control pressure set near the ultimate vacuum degree in the processing container, a precoat is continuously performed in the cleaning step so that a precoat film is formed at least on the surface of the mounting table. It is controlled to be repeated. The step of forming the film is performed with the temperature of the mounting table being 500°C or higher. A film forming apparatus that controls the cleaning step and the precoating step to be performed with the temperature of the mounting table being 450°C or lower.

17. The film forming apparatus according to claim 16, further comprising a plasma source that generates plasma of the gas for film formation.

18. The film forming apparatus according to claim 17, wherein the plasma source generates microwave plasma.

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