Cleaning method and substrate processing system

Abstract

To achieve both suppression of throughput reduction and suppression of particle generation.SOLUTION: A cleaning method for a substrate processing system executes cleaning of a processing chamber when an integrated value of standby time of the processing chamber reaches a reference time. The method increases the standby time of the processing chamber according to cumulative number of substrates processed in the processing chamber when calculating the integrated value of standby time of the processing chamber.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a cleaning method and a substrate processing system. [Background technology]

[0002] In the manufacturing process of semiconductor devices, a substrate processing system equipped with multiple processing chambers is used, and in each processing chamber, film formation processing and etching processing are repeatedly performed on substrates such as semiconductor wafers. In the film formation processing, a portion of the film formation material generated from the film formation gas deposits on the inner walls and components of the processing chamber as reaction products. In the etching processing, reaction products generated during etching also deposit on the inner walls and components of the processing chamber. As the film formation processing and etching processing are repeated, the amount of reaction products deposited on the inner walls and components of the processing chamber increases, and eventually some of the deposited reaction products peel off. The peeled reaction products scatter inside the processing chamber as particles and adhere to the substrates contained inside the processing chamber. Because particles adhering to the substrates degrade the quality of semiconductor devices, the substrate processing system performs cleaning to remove the reaction products deposited on the inner walls and components of the processing chamber to suppress particle generation.

[0003] For example, when cleaning a processing chamber in which a film formation process is performed, cleaning gases such as ClF3 gas, NF3 gas, or Cl2 gas are supplied into the processing chamber, and the deposited reaction products are removed by converting them into sublimable compounds.

[0004] Since cleaning is performed without a substrate being placed inside the processing chamber, film formation processing cannot be performed on the substrate in the processing chamber during cleaning. Therefore, the timing and frequency of cleaning the processing chamber have a significant impact on the throughput of the substrate processing system. Therefore, various methods for determining the timing and frequency of cleaning the processing chamber have been proposed.

[0005] For example, in a method of performing conditioning equivalent to cleaning described in Patent Document 1, a set value N1 is set, which is the cumulative number of substrates processed between one conditioning and the next conditioning. Then, in the processing chamber, conditioning is performed when a first integrated value, which is the cumulative number of substrates processed continuously since the previous conditioning, reaches the set value N1.

[0006] Furthermore, in the substrate processing system described in Patent Document 2, the processing efficiency of the entire system is improved by adjusting the number of processing chambers performing substrate processing and the number of processing chambers performing cleaning.

[0007] In particular, the first integrated value in the conditioning method of Patent Document 1 is the number of substrates processed in the processing chamber consecutively since the previous conditioning (hereinafter referred to as the "cumulative number of processed substrates"). Furthermore, an increase in the cumulative number of processed substrates means an increase in the number of times the film formation process is repeated, and therefore an increase in the cumulative number of processed substrates also increases the amount of deposition of reaction products. Therefore, the conditioning method of Patent Document 1 performs processing chamber conditioning when the amount of deposition of reaction products has increased to a certain extent. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent No. 5695956 [Patent Document 1] Patent No. 6105436 Summary of the Invention [Problem to be solved by the invention]

[0009] The technology according to the present disclosure achieves both suppression of a decrease in throughput and suppression of particle generation. [Means for solving the problem]

[0010] One aspect of the technology disclosed herein is a cleaning method that performs cleaning of a processing chamber when the accumulated value of the standby time of the processing chamber reaches a reference time, and increases the standby time of the processing chamber according to the cumulative number of substrates that have been processed in the processing chamber. [Effects of the Invention]

[0011] According to the technology disclosed herein, it is possible to suppress both a decrease in throughput and the generation of particles. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a plan view showing a schematic configuration of a substrate processing system according to an embodiment of the technology disclosed herein; [Figure 2] 1 is a cross-sectional view schematically illustrating a configuration of a process module included in a substrate processing system. [Figure 3] FIG. 10 is a diagram for explaining a conventional method for determining the timing of cleaning. [Figure 4] 10A and 10B are diagrams for explaining a method for determining the timing of cleaning as a cleaning method according to the present embodiment. [Figure 5] 10A and 10B are diagrams for explaining conversion coefficients used in a method for determining the timing of cleaning in the present embodiment. [Figure 6] 10A and 10B are diagrams for explaining another specific example of a method for determining the timing of cleaning in the present embodiment. [Figure 7] 10A and 10B are diagrams for explaining the adverse effects that occur when the idle time between successive film formation processes is set to an extremely short time in a conventional method for determining the timing of cleaning execution. [Figure 8] 10A and 10B are diagrams for explaining a case where the idle time between successive film formation processes is set extremely short in the method for determining the timing of cleaning in the present embodiment. [Figure 9] 10A and 10B are diagrams for explaining modified examples of conversion coefficients used in the method for determining the timing of cleaning in the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] However, in a processing chamber where a film formation process is performed, reaction products deposited on the inner walls and components are covered by the film-forming material and are difficult to peel off. Therefore, particle generation does not necessarily increase in proportion to the amount of reaction product deposition. Therefore, when cleaning the processing chamber when the amount of reaction product deposition has increased to a certain extent, as in the conditioning method of Patent Document 1, cleaning may be performed in a state where there is almost no possibility of particle generation. In other words, performing cleaning of the processing chamber based on the amount of reaction product deposition may result in unnecessary cleaning. Furthermore, unnecessary cleaning reduces the throughput of the substrate processing system. Therefore, from the perspective of preventing a decrease in throughput, it is not desirable to determine the timing of cleaning based solely on the amount of reaction product deposition, in other words, the cumulative number of processed substrates.

[0014] On the other hand, since the deposited reaction products are left as they are in a standby state when the film formation process is not being performed, it can be said that the reaction products are more likely to peel off and generate particles during the standby time when the processing chamber is in a standby state than during the film formation process. Therefore, in recent years, from the perspective of suppressing a decrease in throughput, a cleaning method has been adopted in which the processing chamber is cleaned when the accumulated standby time of the processing chamber reaches a predetermined reference time.

[0015] However, even if the reaction products deposited during the film formation process are covered with the film-forming material, as the cumulative number of processed wafers increases and the amount of deposited reaction products increases, the reaction products are more likely to peel off and particles are more likely to be generated than when the amount of deposited reaction products is small.

[0016] However, in a cleaning method that determines the timing of cleaning based on the cumulative waiting time of the processing chamber, the amount of deposition of reaction products is not taken into consideration. Therefore, if the cumulative waiting time of the processing chamber does not increase significantly even though the cumulative number of processed wafers increases and the amount of deposition of reaction products increases significantly, cleaning may not be performed for a long time, making it difficult to suppress particle generation.

[0017] In contrast to this, in the technology according to the present disclosure, the timing of cleaning is determined taking into consideration not only the cumulative waiting time of the processing chamber but also the cumulative number of processed wafers.

[0018] An embodiment of the technology according to the present disclosure will be described below with reference to the drawings. FIG. 1 is a plan view showing a schematic configuration of a substrate processing system according to this embodiment. The substrate processing system 1 includes a plurality of process modules (hereinafter referred to as "PMs") 11 that perform various processes on substrates W such as semiconductor wafers. The substrate processing system 1 includes, for example, four PMs 11a, 11b, 11c, and 11d. Each of the PMs 11a, 11b, 11c, and 11d has a chamber (processing chamber) 12 capable of maintaining a reduced pressure atmosphere (vacuum state) inside. The configurations of the PMs 11a, 11b, 11c, and 11d will be described in detail below.

[0019] The substrate processing system 1 also includes a transfer module (hereinafter referred to as "TM") 10 and, for example, two load lock modules (hereinafter referred to as "LLMs") 13a and 13b. The TM 10 has, for example, six side surfaces, and PMs 11a, 11b, 11c, and 11d and LLMs 13a and 13b are disposed adjacent to each side surface of the TM 10. For example, as shown in FIG. 1, the PMs 11a, 11b, 11c, and 11d and the LLMs 13a and 13b are arranged clockwise in a plan view so as to surround the TM 10 in the order of PMs 11a, 11b, 11c, and 11d, and LLMs 13b and 13a. Furthermore, the TM 10 is configured to be able to maintain a reduced pressure atmosphere (vacuum state) inside, similar to the chambers 12 of the PMs 11a, 11b, 11c, and 11d.

[0020] The LLMs 13a and 13b are configured so that their internal spaces can be switched between atmospheric pressure and vacuum. A substrate mounting table 14a for mounting a substrate W thereon is provided inside the LLM 13a, and a substrate mounting table 14b for mounting a substrate W thereon is provided inside the LLM 13b.

[0021] The substrate processing system 1 further includes gate valves 15a, 15b, 15c, 15d, 15e, and 15f. The gate valve 15a is disposed between the TM10 and the PM11a, and the gate valve 15b is disposed between the TM10 and the PM11b. The gate valve 15c is disposed between the TM10 and the PM11c, and the gate valve 15d is disposed between the TM10 and the PM11d. The gate valve 15e is disposed between the TM10 and the LLM13a, and the gate valve 15f is disposed between the TM10 and the LLM13b. Each of the gate valves 15a to 15f is configured as an openable and closable shutter gate. When closed, the gate valves 15a to 15d airtightly seal the chambers 12 of the PM11a, 11b, 11c, and 11d, and when open, allow the transfer of the substrate W between each chamber 12 and the TM10. The gate valves 15e and 15f hermetically seal the TM 10 when closed, and allow the transfer of the substrate W between the TM 10 and the LLMs 13a and 13b when open.

[0022] The substrate processing system 1 also includes a loader module (hereinafter referred to as "LM") 16. The LM 16 has a rectangular shape in horizontal cross section that is long in one direction (the left-right direction in FIG. 1), and is disposed so that its side faces the TM 10, sandwiching the LLMs 13a and 13b between them. The LM 16 includes a circulation system that supplies, for example, nitrogen gas or clean air in a downflow manner into its internal space.

[0023] The substrate processing system 1 further includes gate valves 17a and 17b. The gate valve 17a is disposed between the LLM 13a and the LM 16, and the gate valve 17b is disposed between the LLM 13b and the LM 16. The gate valves 17a and 17b are both configured as shutter gates that can be opened and closed. When closed, the gate valves 17a and 17b airtightly seal the LLMs 13a and 13b, and when open, allow the transfer of substrates W between the LLMs 13a and 13b and the LM 16.

[0024] The substrate processing system 1 also includes an orienter 18 that aligns the substrate W. The orienter 18 is connected to one longitudinal end of the LM 16. The orienter 18 includes a rotating plate 19 that is rotated by a drive motor (not shown), and an optical sensor 20 that is provided on the outer periphery of the rotating plate 19 and that detects the peripheral edge of the substrate W.

[0025] Furthermore, the substrate processing system 1 includes, for example, three load ports 21a, 21b, and 21c. The load ports 21a, 21b, and 21c are arranged adjacent to the side of the LM 16 opposite to the side adjacent to the LLMs 13a and 13b. Cassette containers 22a, 22b, and 22c that accommodate multiple substrates W are attached to the load ports 21a, 21b, and 21c, respectively.

[0026] The substrate processing system 1 also includes a transfer device 23 disposed inside the TM 10 and a transfer device 24 disposed inside the LM 16. The transfer device 23 transfers substrates W between each chamber 12 of the PMs 11a, 11b, 11c, and 11d and the LLMs 13a and 13b. The transfer device 24 transfers substrates W between each cassette container 22a, 22b, and 22c of the load ports 21a, 21b, and 21c, the LLMs 13a and 13b, and the orienter 18.

[0027] The transport device 23 has a base 25, a pair of transport arms 26a, 26b connected to the base 25 and arranged to face each other, a fork 27a provided at the tip of the transport arm 26a, and a fork 27b provided at the tip of the transport arm 26b. Each of the transport arms 26a, 26b is configured to be able to bend and extend, and further configured to be able to rotate about the rotation axis of the base 25. In the transport device 23, the forks 27a, 27b place the substrate W thereon, and the transport arms 26a, 26b rotate and bend and extend to transport the substrate W.

[0028] The transport device 24 is configured to be movable in the longitudinal direction of the LM 16 (left and right direction in FIG. 1) along guide rails 28 arranged inside the LM 16. The transport device 24 also has a pair of transport arm units 29a, 29b arranged in two stages, one above the other, a fork 30a provided at the tip of the transport arm unit 29a, and a fork 30b provided at the tip of the transport arm unit 29b. Each of the transport arm units 29a, 29b is configured to be bendable, extendable, and rotatable. In the transport device 24, the forks 30a, 30b place the substrate W on them, and the transport arm units 29a, 29b swivel and bend to transport the substrate W.

[0029] Furthermore, the substrate processing system 1 includes a control unit 31 to which each component of the substrate processing system 1 is connected. The control unit 31 has, for example, a CPU and memories such as a ROM and a RAM, and controls the operation of each component of the substrate processing system 1 by causing the CPU to execute a program loaded from the ROM to the RAM. As a result, film formation processing and cleaning of the substrate W are performed in each of the chambers 12 of the PMs 11a, 11b, 11c, and 11d.

[0030] 2 is a cross-sectional view showing the schematic configuration of PMs 11a, 11b, 11c, and 11d. Since PMs 11a, 11b, 11c, and 11d all have the same configuration, only the configuration of PM 11a is shown in FIG.

[0031] The PM 11a includes a chamber 12 (processing chamber) in which a substrate W is processed, and an exhaust chamber 32 connected to the chamber 12. The chamber 12 has a disk-shaped ceiling 33, a plate-shaped bottom 34, and a sidewall 35 connecting the ceiling 33 and the bottom 34, and has, for example, a substantially cylindrical shape. A loading / unloading port (not shown) is formed in the sidewall 35 for loading / unloading the substrate W to / from the TM 10. An opening 34a is formed in the center of the bottom 34. The exhaust chamber 32 is connected to the bottom 34 so as to cover the opening 34a.

[0032] The exhaust chamber 32 has a flange 36, a plate-shaped bottom 37, and a sidewall 38 connecting the flange 36 and the bottom 37. The flange 36 is joined to the bottom 34 of the chamber 12. An exhaust hole 39 is formed in the sidewall 38. Not only the chamber 12 but also the exhaust chamber 32 is configured to be able to maintain a reduced pressure atmosphere (vacuum state) inside. O-rings are provided as sealing members at the joints between the chamber 12 and the exhaust chamber 32, as well as at the joints between the components constituting the chamber 12 and the exhaust chamber 32, to ensure airtightness of these joints. For example, an annular O-ring 40 is provided at the joint between the bottom 34 of the chamber 12 and the flange 36 of the exhaust chamber 32. In addition, an annular O-ring 41 is provided at the joint between the ceiling 33 and the sidewall 35 of the chamber 12.

[0033] PM11a also includes an exhaust device 42 disposed outside exhaust chamber 32, an exhaust pipe 43 connecting exhaust hole 39 and exhaust device 42, and a valve 44 provided midway along exhaust pipe 43. When valve 44 is closed, it ensures airtightness of chamber 12 and exhaust chamber 32, and when it is open, it allows exhaust device 42 to reduce the pressure in chamber 12 and exhaust chamber 32. The exhaust device 42 reduces the pressure inside chamber 12 and exhaust chamber 32 to a predetermined vacuum level.

[0034] The PM 11a further includes a substrate mounting table 45 disposed inside the chamber 12, and a support member 46 that supports the substrate mounting table 45. The substrate mounting table 45 is flat, and a substrate W is horizontally mounted on its upper surface, a substrate mounting surface S. One end of the support member 46 is fixed to the center of the lower surface of the substrate mounting table 45, and the other end of the support member 46 is fixed to the bottom 37 of the exhaust chamber 32. The substrate mounting table 45 has a plurality of support pins (not shown) that are provided so as to be able to protrude and retract into the substrate mounting surface S. The plurality of support pins are moved up and down by an arbitrary lifting mechanism, and separate the substrate W from the substrate mounting surface S, enabling the transfer device 23 to transfer the substrate W.

[0035] The PM 11a also includes a heater 47, a heater power supply 48, and a thermocouple (TC) 49. The heater 47 and a temperature measurement portion 49a of the thermocouple 49 are embedded in the substrate mounting table 45. The heater power supply 48 is disposed outside the chamber 12 or the exhaust chamber 32. The heater 47 is connected to the heater power supply 48, for example, via wiring passing through the inside of the support member 46. The heater power supply 48 supplies power to the heater 47 to heat the substrate W mounted on the substrate mounting table 45 to a predetermined temperature. The temperature of the substrate mounting table 45 is measured by the thermocouple 49.

[0036] The PM11a further includes a shower head 50 provided on the ceiling 33 of the chamber 12. The shower head 50 has a gas diffusion space 51 formed therein and a plurality of gas outlet holes 52 that connect the gas diffusion space 51 to the interior of the chamber 12. The PM11a also includes a gas inlet pipe 53 that connects to the gas diffusion space 51, and a gas supply source 54 that is disposed outside the chamber 12 and the exhaust chamber 32. The PM11a also includes a gas pipe 55 that connects the gas inlet pipe 53 and the gas supply source 54, and an MFC (mass flow controller) 56 that is provided midway along the gas pipe 55.

[0037] The gas supply source 54 supplies a film-forming source gas used in the film forming process, a cleaning gas for cleaning the inside of the chamber 12 and the inside of the exhaust chamber 32, a purge gas for replacing the atmosphere inside the chamber 12 and the inside of the exhaust chamber 32, etc. These gases are supplied to the gas diffusion space 51 via a gas pipe 55 and a gas introduction pipe 53, and are discharged into the chamber 12 from a plurality of gas discharge holes 52.

[0038] The PM 11a includes a high-frequency power supply 57 disposed outside the chamber 12 and the exhaust chamber 32, wiring 58 connecting the shower head 50 and the high-frequency power supply 57, and a matching box 59 provided midway along the wiring 58. The high-frequency power supply 57 supplies high-frequency power to the shower head 50 to convert the film-forming source gas supplied into the chamber 12 into plasma.

[0039] In the PM 11a, a thin film such as a Ti film or a TiN film is formed on the surface of the substrate W by a film formation process, for example, by chemical vapor deposition. When performing the film formation process in the PM 11a, first, the inside of the chamber 12 and the inside of the exhaust chamber 32 are evacuated. Next, the substrate W is placed on the substrate mounting table 45, and the substrate W is heated by the heater 47. Next, a film formation source gas is discharged into the chamber 12 from each gas discharge hole 52 of the shower head 50. Note that, to promote film formation, high-frequency power may be supplied from the high-frequency power source 57 to the shower head 50 to convert the film formation source gas into plasma.

[0040] In the substrate processing system 1, as film formation processes are repeated in each chamber 12 of PMs 11a, 11b, 11c, and 11d, the amount of reaction products deposited on the inner walls and components of each chamber 12 increases. Eventually, some of the deposited reaction products peel off, generating particles. Therefore, in the substrate processing system 1, cleaning is performed to remove the reaction products deposited on the inner walls and components of each chamber 12 to suppress particle generation. At this time, a cleaning gas containing at least one of ClF gas, NF gas, and Cl gas is supplied into each chamber 12 to convert the deposited reaction products into sublimable compounds and remove them. The control unit 31 then determines the timing of cleaning for each chamber 12.

[0041] In order to prevent a decrease in throughput, the substrate processing system 1 employs a cleaning method in which cleaning of the corresponding chamber 12 is performed when the accumulated value of the standby (idle) time for each chamber 12 reaches a predetermined reference time. Hereinafter, the predetermined reference time will be referred to as the "cleaning execution reference time." In the substrate processing system 1, the control unit 31 manages the accumulated value of the idle time for each chamber 12 and determines the timing of cleaning for each chamber 12 based on the accumulated value of the idle time for each chamber 12.

[0042] 3 is a diagram illustrating a conventional method for determining the timing of cleaning. In this method, the control unit 31 simply determines that cleaning should be performed when the accumulated idle time reaches the cleaning execution reference time. In addition, in the method of determining the timing of cleaning shown in FIG. 3, the accumulated value of the actual, unconverted idle time is compared with the cleaning execution reference time.

[0043] 3, for example, the cleaning execution reference time is set to 180 minutes, and continuous film formation processes are repeated to continuously perform film formation processes on 300 substrates W, with an idle time of 60 minutes between each continuous film formation process. Note that in the following diagrams, continuous film formation processes are represented by rectangles, idle times are represented by arrows, and cleaning is represented by circles.

[0044] 3, the integrated value of the idle time is 120 minutes when the third consecutive film formation process is completed, and when 60 minutes of idle time has elapsed since the end of the third consecutive film formation process, the integrated value of the idle time at this point becomes 180 minutes. Therefore, the control unit 31 determines that cleaning should be performed when 60 minutes of idle time has elapsed since the end of the third consecutive film formation process.

[0045] However, as the cumulative number of processed substrates W, which is the number of substrates W that have been subjected to film formation processing consecutively since the previous cleaning, increases and the amount of deposition of reaction products increases, particles are more likely to be generated even if the deposited reaction products in the consecutive film formation processes are covered with film formation material. However, in the cleaning method of Figure 3, the timing of cleaning is determined simply based on the integrated value of idle time. Therefore, even if the amount of deposition of reaction products has increased significantly and particles are more likely to be generated, if the integrated value of idle time has not increased significantly, cleaning may not be performed for a long time, and it may be difficult to suppress particle generation.

[0046] In contrast to this, in this embodiment, the timing of cleaning is determined taking into consideration not only the accumulated idle time of the processing chamber but also the accumulated number of processed wafers.

[0047] FIG. 4 is a diagram for explaining a method for determining the timing of cleaning as a cleaning method according to the present embodiment, and FIG. 5 is a diagram for explaining a conversion coefficient used in the method for determining the timing of cleaning of FIG. 4.

[0048] 4, when calculating the integrated value of the idle time, the idle time between successive film formation processes is increased according to the cumulative number of processed wafers. Specifically, the idle time between successive film formation processes is multiplied by a conversion coefficient (weighting coefficient) whose value changes according to the cumulative number of processed wafers. Then, when the integrated value of the idle time between successive film formation processes multiplied by the conversion coefficient (hereinafter referred to as the "converted idle time") reaches the cleaning execution reference time, the control unit 31 determines that cleaning should be performed. As the conversion coefficient in this embodiment, for example, the conversion coefficient shown in the following formula (1) is used.

[0049] Conversion coefficient = a × (cumulative processed number - conversion start number) + b …(1)

[0050] Here, a is a conversion coefficient, and is set to, for example, 1 / 900, and b is a conversion constant, and is set to, for example, 1. The coefficient a and the constant b are not limited to the values ​​described above, but the coefficient a and the constant b are set so that the conversion coefficient is 1 or greater.

[0051] The conversion start number (a predetermined number) is the number of processed substrates W that serves as a reference for increasing the subsequent idle time. In this embodiment, after the cumulative number of processed substrates exceeds the conversion start number, the conversion coefficient in the above formula (1) is multiplied by the idle time between successive film formation processes to calculate the converted idle time. The converted idle time is then used to calculate the integrated value of the idle time. In this embodiment, the conversion start number is set to, for example, 300.

[0052] On the other hand, until the cumulative number of processed wafers exceeds the conversion start number, the conversion coefficient in the above formula (1) is not multiplied by the idle time between successive film-forming processes, and the actual idle time is used to calculate the integrated value of the idle time. Here, using the actual idle time is equivalent to multiplying the idle time between successive film-forming processes by a conversion coefficient fixed at 1.

[0053] Therefore, as shown in FIG. 5, the conversion factor remains 1 until the cumulative number of processed sheets exceeds the conversion start number, and once the cumulative number of processed sheets exceeds the conversion start number, the conversion factor becomes greater than 1.

[0054] 4, a method for determining the timing of cleaning will be specifically described. Here, too, the cleaning execution reference time is set to 180 minutes, continuous film formation processes are repeated in which film formation processes are performed consecutively on 300 substrates W, and the actual idle time between each continuous film formation process is set to 60 minutes. Furthermore, the conversion coefficient a is set to 1 / 900, the conversion constant b is set to 1, and the conversion start number is set to 300.

[0055] First, after the first continuous film formation process is completed, the cumulative number of processed wafers is 300, which is less than the conversion start number (300), so the actual idle time is used to calculate the integrated value of the idle time.The integrated value of the idle time at this time is 60 minutes, which is less than the cleaning execution reference time, so the control unit 31 determines that cleaning should not be performed yet.

[0056] Next, after the second continuous film formation process is completed, the cumulative number of processed wafers is 600, which exceeds the conversion start number. Therefore, when calculating the integrated value of idle time, the idle time after the second continuous film formation process is multiplied by a conversion coefficient. The conversion coefficient used at this time is 1.33 from the above formula (1), and the converted idle time is 80 minutes. This converted idle time (80 minutes) is then used to calculate the integrated value of idle time. However, the integrated value of idle time at this time is 140 minutes, which is not yet the cleaning execution reference time, so the control unit 31 determines that cleaning should not be performed.

[0057] Next, after the third consecutive film formation process, the cumulative number of processed wafers is 900, exceeding the conversion start number. Therefore, when calculating the integrated idle time, the idle time after the third consecutive film formation process is multiplied by a conversion factor. The conversion factor is 1.67, as calculated using Equation (1). The converted idle time is still used to calculate the integrated idle time. However, after 24 minutes of actual idle time has elapsed, the converted idle time becomes 40 minutes. At this point, the integrated idle time becomes 180 minutes, reaching the cleaning execution reference time. That is, after the third consecutive film formation process, the control unit 31 determines that cleaning should be performed when 24 minutes of actual idle time has elapsed (when the integrated actual idle time reaches 144 minutes). This allows cleaning to be performed earlier than in the example of FIG. 3 after the third consecutive film formation process, thereby suppressing particle generation. In other words, the cleaning method according to this embodiment can simultaneously suppress a decrease in throughput and particle generation.

[0058] FIG. 6 is a diagram for explaining another specific example of the method for determining the timing of cleaning execution in this embodiment.

[0059] First, a case will be described in which continuous film formation processing is repeated to perform film formation processing on 400 substrates W (FIG. 6(A)). In this case, the cleaning execution reference time is set to 180 minutes, and the actual idle time between each continuous film formation processing is set to 60 minutes. Furthermore, the conversion coefficient a is set to 1 / 900, the conversion constant b is set to 1, and the conversion start number is set to 300.

[0060] In this case, after the first continuous film formation process is completed, the cumulative number of processed wafers is 400, which exceeds the conversion start number (300 wafers). Therefore, when calculating the integrated value of the idle time, the idle time after the first continuous film formation process is multiplied by a conversion coefficient. The conversion coefficient used at this time is 1.11 from the above formula (1), and the converted idle time is 67 minutes. However, the integrated value of the idle time at this time is also 67 minutes, which has not yet reached the cleaning execution reference time, so the control unit 31 determines that cleaning should not be performed yet.

[0061] Next, after the second continuous film formation process is completed, the cumulative number of processed wafers is 800, which also exceeds the conversion start number. Therefore, when calculating the integrated value of idle time, the idle time after the second continuous film formation process is multiplied by a conversion coefficient. The conversion coefficient used at this time is 1.56 from the above formula (1), and the converted idle time is 93 minutes. This converted idle time (93 minutes) is then used to calculate the integrated value of idle time. However, the integrated value of idle time at this time is 160 minutes, which is not yet the cleaning execution reference time, so the control unit 31 determines that cleaning should not be performed.

[0062] Next, after the third consecutive film formation process, the cumulative number of processed wafers is 1,200, exceeding the conversion start number. Therefore, when calculating the integrated idle time, the idle time after the third consecutive film formation process is multiplied by a conversion factor. The conversion factor is 2.0, as calculated using equation (1). The converted idle time is still used to calculate the integrated idle time. However, after 10 minutes of actual idle time has elapsed, the converted idle time becomes 20 minutes. At this point, the integrated idle time becomes 180 minutes, reaching the cleaning execution reference time. In other words, after the third consecutive film formation process, the control unit 31 determines that cleaning should be performed when 10 minutes of actual idle time has elapsed (when the integrated actual idle time reaches 130 minutes). As a result, cleaning is performed after the third consecutive film formation process, much earlier than when 60 minutes of actual idle time has elapsed.

[0063] Next, a case where continuous film formation processing is repeated to perform film formation processing on 500 substrates W will be described (FIG. 6(B)). In this case, the cleaning execution reference time is set to 180 minutes, and the actual idle time between each continuous film formation processing is set to 60 minutes. Furthermore, the conversion coefficient a is set to 1 / 900, the conversion constant b is set to 1, and the conversion start number is set to 300.

[0064] In this case, after the first continuous film formation process is completed, the cumulative number of processed wafers is 500, which exceeds the conversion start number (300 wafers). Therefore, when calculating the integrated value of the idle time, the idle time after the first continuous film formation process is multiplied by a conversion coefficient. The conversion coefficient used at this time is 1.22 from the above formula (1), and the converted idle time is 73 minutes. However, the integrated value of the idle time at this time is also 73 minutes, which does not reach the cleaning execution reference time, so the control unit 31 determines that cleaning should not be performed yet.

[0065] Next, after the second continuous film formation process is completed, the cumulative number of processed wafers is 1,000, which also exceeds the conversion start number. Therefore, when calculating the integrated value of the idle time, the idle time after the second continuous film formation process is multiplied by a conversion factor. The conversion factor is 1.78 from equation (1) above, and the converted idle time is 107 minutes. This converted idle time (107 minutes) is then used to calculate the integrated value of the idle time. Since the integrated value of the idle time at this time is 180 minutes, the integrated value of the idle time reaches the cleaning execution reference time at this point. In other words, after the second continuous film formation process is completed (when the actual integrated value of the idle time reaches 120 minutes), the control unit 31 determines that cleaning should be performed immediately. As a result, cleaning is performed immediately after the second continuous film formation process is completed.

[0066] As described above, when a continuous film formation process is repeated in which film formation is performed on 300 substrates W in succession, cleaning is performed when the accumulated value of the actual idle time reaches 144 minutes. When a continuous film formation process is repeated in which film formation is performed on 400 substrates W in succession, cleaning is performed when the accumulated value of the actual idle time reaches 130 minutes. When a continuous film formation process is repeated in which film formation is performed on 500 substrates W in succession, cleaning is performed when the accumulated value of the actual idle time reaches 120 minutes. In other words, according to the cleaning method of this embodiment, the more substrates W that are subjected to film formation in the continuous film formation process, the earlier cleaning can be performed.

[0067] To perform cleaning earlier, it is possible to simply shorten the cleaning execution reference time. For example, it is possible to set the cleaning execution reference time to 140 minutes. In this case, in the example shown in FIG. 3, when 20 minutes of idle time has elapsed since the end of the third consecutive film formation process, the integrated value of the idle time at this point is 140 minutes. Therefore, the control unit 31 determines that cleaning should be performed when 20 minutes of idle time has elapsed since the end of the third consecutive film formation process. This allows cleaning to be performed earlier than when the cleaning execution reference time is set to 180 minutes.

[0068] However, as shown in Figure 7, if the actual idle time between successive film formation processes is set to an extremely short 10 minutes, the cumulative value of the idle time will still be 20 minutes when the third successive film formation process is completed. Therefore, when the idle time after the third successive film formation process has finished has reached 120 minutes, the control unit 31 will decide to perform cleaning. In other words, even if the cleaning execution reference time is shortened, the idle time after the third successive film formation process finishes until cleaning is performed will be very long, which may increase the risk of particle generation.

[0069] In contrast, consider applying the cleaning method according to this embodiment to a case where the actual idle time between successive film formation processes is set to an extremely short time of 10 minutes. Figure 8 is a diagram for explaining a case where the idle time between successive film formation processes is set to an extremely short time in the method for determining the timing of cleaning execution according to this embodiment. In this cleaning method, the cleaning execution reference time is not shortened but set to 180 minutes, and successive film formation processes are repeated in which film formation processes are performed successively on 300 substrates W. Furthermore, the conversion coefficient a is set to 1 / 900, the conversion constant b is set to 1, and the conversion start number is set to 300.

[0070] First, after the first continuous film formation process is completed, the cumulative number of processed wafers is 300, which is not more than the conversion start number, so the actual idle time is used to calculate the integrated value of the idle time.The integrated value of the idle time at this time is 10 minutes, which is not yet the cleaning execution reference time, so the control unit 31 determines that cleaning should not be performed yet.

[0071] Next, after the second continuous film formation process is completed, the cumulative number of processed wafers is 600, which exceeds the conversion start number. Therefore, when calculating the integrated value of the idle time, the idle time after the second continuous film formation process is multiplied by a conversion coefficient. The conversion coefficient used at this time is 1.33 from the above formula (1), and the converted idle time is 13 minutes. This converted idle time is then used to calculate the integrated value of the idle time. However, the integrated value of the idle time at this time is 23 minutes, which is not yet the cleaning execution reference time, so the control unit 31 determines that cleaning should not be performed yet.

[0072] Next, after the third continuous film formation process, the cumulative number of processed wafers is 900, exceeding the conversion start number. Therefore, when calculating the integrated value of the idle time, the idle time after the third continuous film formation process is multiplied by a conversion factor. The conversion factor is 1.67, as calculated using equation (1). The converted idle time is still used to calculate the integrated value of the idle time. However, when 94 minutes of actual idle time has elapsed, the converted idle time becomes 157 minutes. Therefore, at this point, the integrated value of the idle time becomes 180 minutes, reaching the cleaning execution reference time. In other words, after the third continuous film formation process, when 94 minutes of actual idle time has elapsed (when the integrated value of the actual idle time reaches 114 minutes), the control unit 31 determines that cleaning should be performed.

[0073] 7, where cleaning is performed when 120 minutes of idle time has elapsed after the end of the third consecutive film formation process. That is, according to the cleaning method of this embodiment, cleaning can be performed earlier than when the cleaning execution reference time is simply shortened, and it can be said that the cleaning method has a high potential for suppressing particle generation.

[0074] Incidentally, cleaning with a substrate, in which a cleaning substrate such as a dummy wafer is placed inside the chamber 12 and cleaning is performed, involves transporting the cleaning substrate. In the substrate processing system 1, the cleaning substrate is transported via the TM 10 shared by the PMs 11a, 11b, 11c, and 11d. Therefore, cleaning with a substrate interrupts the progress of film formation processes in PMs other than the PM being cleaned. Therefore, the cleaning method according to this embodiment employs cleaning without a substrate, which is performed without placing a cleaning substrate inside the chamber 12 of each of the PMs 11a, 11b, 11c, and 11d. In particular, the cleaning method according to this embodiment randomly determines the timing of cleaning in each of the chambers 12 of the PMs 11a, 11b, 11c, and 11d. Therefore, cleaning without a substrate, which can be performed immediately once the timing is determined, is suitable for the cleaning method according to this embodiment.

[0075] Although the preferred embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments, and various modifications and changes are possible within the scope of the gist of the present disclosure.

[0076] For example, the conversion coefficient is not limited to that shown in the above formula (1), and other forms are possible as long as the conversion coefficient is 1 or greater. For example, the conversion coefficient in the above formula (1) changes linearly after the cumulative number of processed sheets exceeds the conversion start number. However, as shown in FIG. 9(A), a conversion coefficient that changes nonlinearly after the cumulative number of processed sheets exceeds the conversion start number may be used. Also, as shown in FIG. 9(B), a conversion start number may not be set, and a conversion coefficient that increases immediately as the cumulative number of processed sheets increases may be used. However, regardless of the form of the conversion coefficient, it is preferable that the conversion coefficient increase as the cumulative number of processed sheets increases, and in particular, a form in which the conversion coefficient increases continuously is preferable.

[0077] In the above-described embodiment, the idle time is multiplied by a conversion coefficient that varies depending on the cumulative number of processed sheets to increase the idle time in accordance with the cumulative number of processed sheets. However, the idle time may also be increased in accordance with the cumulative number of processed sheets by adding an additional time, the value of which varies depending on the cumulative number of processed sheets, to the idle time. In this case, too, the additional time is added to the idle time after the cumulative number of processed sheets exceeds the conversion start number, and the additional time preferably increases in accordance with the cumulative number of processed sheets. In particular, a form in which the additional time increases continuously is preferred.

[0078] In the above-described embodiment, the PMs 11a, 11b, 11c, and 11d perform a film formation process on the substrate W. However, the cleaning method according to the embodiment can also be applied to a case where the PMs 11a, 11b, 11c, and 11d perform an etching process on the substrate W. In addition, in the above-described embodiment, the film formation process is performed on a semiconductor wafer as the substrate W. However, the cleaning method according to the embodiment can also be applied to a case where a film formation process is performed on a large glass substrate or ceramic substrate used in a liquid crystal display device, an organic EL display, or the like. [Explanation of symbols]

[0079] W substrate 1. Substrate Processing System 11a, 11b, 11c, 11d PM 12 Chambers 31 Control Unit

Claims

1. A cleaning method for cleaning a processing chamber when an integrated value of standby time of the processing chamber reaches a reference time, comprising: A cleaning method, wherein when calculating an integrated value of standby time of the processing chamber, the standby time of the processing chamber is increased in accordance with the cumulative number of substrates that have been processed in the processing chamber.

2. 2. The cleaning method according to claim 1, wherein the standby time of the processing chamber is increased by multiplying the standby time of the processing chamber by a weighting coefficient according to the cumulative number of substrates processed in the processing chamber.

3. The cleaning method according to claim 2 , wherein the weighting factor is 1 or greater.

4. the weighting coefficient is 1 until the cumulative number of substrates processed in the processing chamber exceeds a predetermined number; 4. The cleaning method according to claim 3, wherein the weighting coefficient becomes greater than 1 when the cumulative number of substrates processed in the processing chamber exceeds the predetermined number.

5. 3. The cleaning method according to claim 2, wherein the weighting coefficient increases with an increase in the cumulative number of substrates processed in the processing chamber.

6. 2. The cleaning method according to claim 1, wherein the standby time of the processing chamber is increased by adding an additional time according to the cumulative number of substrates processed in the processing chamber to the standby time of the processing chamber.

7. The cleaning method according to claim 1 , wherein the cleaning of the processing chamber is performed in a state where the processing chamber does not contain the substrate.

8. The cleaning of the processing chamber is performed using ClF ３ Gas, NF ３ Gas and Cl ２ 2. The cleaning method according to claim 1, wherein reaction products deposited on the inner walls and components of the processing chamber are removed by a cleaning gas containing at least one of the following gases:

9. A substrate processing system comprising at least one processing chamber and a controller, the control unit executes cleaning of the processing chamber when an accumulated value of the waiting time of the processing chamber reaches a reference time, and when calculating the accumulated value of the waiting time of the processing chamber, increases the waiting time of the processing chamber in accordance with the accumulated number of substrates that have been processed in the processing chamber.

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