Substrate processing apparatus and substrate processing method

Abstract

To provide a substrate processing apparatus and a substrate processing method that can reuse a processing liquid while adjusting the ozone concentration in the processing liquid in a configuration for processing a substrate by using a processing liquid in which ozone gas is dissolved.SOLUTION: A substrate processing apparatus 1 includes a substrate processing unit 2 for processing a substrate W with a sulfuric-acid-containing liquid in which ozone is dissolved, a collection tank 3 for collecting the sulfuric-acid-containing liquid discharged from the substrate processing unit 2, a recovery pipe 4 connecting the substrate processing unit 2 and the recovery tank 3, a recovery tank heater 26 for heating the sulfuric-acid-containing liquid in the recovery tank 3 to a first temperature, a supply piping system 5 for supplying the sulfuric-acid-containing liquid in the recovery tank 3 to the substrate processing unit 2, and an ozone gas pipe 6 for supplying ozone gas to the supply piping system 5 to mix the ozone gas with the sulfuric-acid-containing liquid passing through the supply piping system 5.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a substrate processing apparatus and a substrate processing method for processing a substrate. Substrates to be processed include, for example, semiconductor wafers, substrates for FPDs (Flat Panel Displays) such as liquid crystal displays and organic EL (Electroluminescence) displays, substrates for optical disks, substrates for magnetic disks, substrates for magneto-optical disks, substrates for photomasks, ceramic substrates, substrates for solar cells, and the like. [Background technology]

[0002] The following Patent Document 1 discloses a substrate processing apparatus that removes resist from a substrate using sulfuric acid mixed with microbubbles of ozone gas. In the substrate processing apparatus of the following Patent Document 1, the concentration of the sulfuric acid is measured after the resist is removed from the substrate, and it is determined whether the sulfuric acid can be reused. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2010-21335 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the substrate processing apparatus of Patent Document 1, the concentration of ozone remaining in the sulfuric acid is not adjusted when the sulfuric acid is reused. Therefore, if ozone remains in the sulfuric acid to be reused, ozone gas is further mixed into the sulfuric acid to be reused, so that the concentration of ozone in the sulfuric acid supplied to the substrate may become higher than expected. Therefore, one object of the present invention is to provide a substrate processing apparatus and a substrate processing method in which a processing liquid containing dissolved ozone gas is used to process a substrate, and the processing liquid can be reused while adjusting the ozone concentration in the processing liquid. [Means for solving the problem]

[0005] One embodiment of the present invention provides a substrate processing apparatus comprising: a substrate processing unit for processing substrates with a processing liquid having ozone dissolved therein; a recovery tank for recovering the processing liquid discharged from the substrate processing unit; a recovery piping connecting the substrate processing unit and the recovery tank; a heating member for heating at least one of the processing liquid in the recovery piping and the processing liquid in the recovery tank to a first temperature; a supply piping system for supplying the processing liquid in the recovery tank to the substrate processing unit; and an ozone gas piping for supplying ozone gas to the supply piping system and mixing the ozone gas with the processing liquid passing through the supply piping system.

[0006] According to this substrate processing apparatus, the processing liquid used for processing the substrate is heated to a first temperature in at least one of the recovery pipe and the recovery tank, so that ozone contained in the processing liquid is generated as ozone gas, and the ozone concentration in the processing liquid is reduced. The processing liquid in the recovery tank is supplied to the substrate processing unit through a supply piping system. The processing liquid passing through the supply piping system is mixed with ozone gas supplied from an ozone gas piping to the supply piping system before being supplied to the substrate processing unit. Therefore, the ozone gas is dissolved in the processing liquid, and the processing liquid with a sufficiently increased ozone concentration is supplied to the substrate processing unit.

[0007] As described above, after intentionally removing ozone from the processing liquid used for processing a substrate, the processing liquid can be reused for processing a substrate by dissolving ozone gas in the processing liquid. Therefore, the processing liquid can be reused while adjusting the ozone concentration in the processing liquid. One embodiment of the present invention provides a substrate processing apparatus including a substrate processing unit for processing substrates with a processing liquid having ozone dissolved therein, a recovery tank for recovering the processing liquid discharged from the substrate processing unit, a recovery piping connecting the substrate processing unit and the recovery tank, a heating member including at least one of a recovery piping heater for heating the processing liquid in the recovery piping in the recovery piping and a recovery tank heater for heating the processing liquid in the recovery tank in the recovery tank, heating the processing liquid to a first temperature, a supply piping system for supplying the processing liquid in the recovery tank to the substrate processing unit, and an ozone gas piping for supplying ozone gas to the supply piping system and mixing the ozone gas with the processing liquid passing through the supply piping system. In one embodiment of the present invention, the substrate processing apparatus further includes a temperature adjusting member that adjusts a temperature of the processing liquid passing through the supply piping system to a second temperature lower than the first temperature.

[0008] According to this substrate processing apparatus, the temperature of the processing liquid passing through the supply piping system is adjusted to a second temperature (e.g., a temperature of 80° C. or more and 130° C. or less) lower than a first temperature (e.g., a temperature of 150° C. or more and 200° C. or less), which is the temperature of the processing liquid in the recovery tank. That is, after the processing liquid is heated to the first temperature to sufficiently reduce the ozone concentration in the processing liquid, the temperature of the processing liquid is adjusted to the second temperature. By mixing the ozone gas supplied from the ozone gas piping to the supply piping system with the processing liquid whose temperature has been sufficiently reduced, the ozone gas can be dissolved in the processing liquid. In this way, after the ozone is sufficiently removed from the processing liquid, the ozone concentration in the processing liquid can be increased again. This makes it possible to precisely adjust the ozone concentration in the processing liquid supplied from the supply piping system to the substrate processing unit.

[0009] In one embodiment of the present invention, the temperature control member is connected to the supply piping system upstream of the ozone gas pipe. Therefore, the temperature of the processing liquid is adjusted to the second temperature before the ozone gas supplied from the ozone gas pipe to the supply piping system is mixed with the processing liquid. Therefore, the ozone gas supplied to the supply piping system can be quickly dissolved in the processing liquid.

[0010] In one embodiment of the present invention, the treatment liquid is a sulfuric acid-containing liquid that contains sulfuric acid. When the treatment liquid is a sulfuric acid-containing liquid, a sulfuric acid-ozone mixed liquid (SOM liquid) suitable for resist removal processing can be formed by dissolving ozone gas in the sulfuric acid-containing liquid. For example, the resist layer can be removed by supplying the SOM liquid to a substrate having a silicon layer having a main surface and a resist layer formed on a protection region of the main surface of the silicon layer.

[0011] When removing the resist layer with an SOM liquid, if the ozone concentration in the SOM liquid is too high, the surface layer of the main surface of the silicon layer in areas other than the protection area may be oxidized, resulting in the formation of an unintended oxide layer. Therefore, if ozone is intentionally removed from the sulfuric acid-containing liquid used in the resist removal process of the substrate and then ozone gas is dissolved in the sulfuric acid-containing liquid, the sulfuric acid-containing liquid can be reused for the resist removal process, thereby preventing unintended oxidation of the surface layer of the silicon layer.

[0012] In one embodiment of the present invention, the supply piping system includes a storage tank for storing the processing liquid, an upstream supply piping for transporting the processing liquid from the recovery tank to the storage tank, and a downstream supply piping to which the ozone gas piping is connected and which supplies the processing liquid in the storage tank toward the substrate processing unit. According to this substrate processing apparatus, the processing liquid, the ozone concentration of which has been reduced by heating at least one of the recovery piping and the recovery tank, can be stored in the storage tank. The processing liquid in the storage tank is supplied to the substrate processing unit by the downstream supply piping. Since the downstream supply piping is connected to the ozone gas piping, the processing liquid is mixed with ozone gas immediately before being supplied to the substrate processing unit. Therefore, it is possible to prevent the processing liquid from being mixed with ozone gas and generating ozone gas, which would reduce the ozone concentration in the processing liquid, during the period from when the processing liquid is mixed with the ozone gas to when the processing liquid is supplied to the substrate processing unit. This makes it possible to accurately adjust the ozone concentration in the processing liquid supplied to the substrate processing unit from the supply piping system.

[0013] In one embodiment of the present invention, the substrate processing apparatus further includes an ozone concentration meter for measuring an ozone concentration in the processing liquid in the recovery tank or an ozone concentration in a space in contact with the liquid surface of the processing liquid in the recovery tank. According to this substrate processing apparatus, the ozone concentration in the processing liquid in the collection tank is directly or indirectly detected by the ozone concentration meter, and therefore it is possible to determine whether or not ozone gas has been sufficiently removed from the processing liquid in the collection tank by heating with the heating member.

[0014] In one embodiment of the present invention, the substrate processing apparatus further includes a switching valve for switching on and off an inflow of the processing liquid from the recovery tank to the supply piping system, and a controller for controlling the switching valve based on a detection result of the ozone concentration meter, the controller opening the switching valve when the concentration detected by the ozone concentration meter is equal to or lower than a predetermined threshold, and closing the switching valve when the detected concentration is higher than the predetermined threshold.

[0015] According to this substrate processing apparatus, if the ozone concentration is higher than a threshold value, the switching valve is closed to prohibit the processing liquid from flowing into the supply piping system from the recovery tank. If the ozone concentration is equal to or lower than the threshold value, the switching valve is opened to allow the processing liquid to flow into the supply piping system. Therefore, only the processing liquid whose ozone concentration is equal to or lower than the threshold value can be automatically flowed into the supply piping system. Therefore, the ozone concentration in the processing liquid can be adjusted more accurately in the supply piping system.

[0016] Another embodiment of the present invention provides a substrate processing method including a supply step of supplying a processing liquid from a supply piping system to a substrate processing unit for processing substrates with a processing liquid having ozone dissolved therein; a recovery step of recovering the processing liquid from the substrate processing unit to a recovery tank via a recovery piping; a heating step of heating at least one of the processing liquid in the recovery tank and the processing liquid passing through the recovery piping so that the temperature of the processing liquid in the recovery tank becomes a first temperature; a liquid delivery step of delivering the processing liquid heated by the heating step to the supply piping system; a temperature adjustment step of adjusting the temperature of the processing liquid in the supply piping system to a second temperature lower than the first temperature; and an ozone gas mixing step of mixing ozone gas with the processing liquid in the supply piping system whose temperature has been adjusted by the temperature adjustment step.

[0017] This substrate processing method provides the same effects as those of the above-described embodiment. In another embodiment of the present invention, the first temperature may be a temperature not lower than 150°C and not higher than 200°C, and the second temperature may be a temperature not lower than 80°C and not higher than 130°C. In another embodiment of the present invention, the treatment liquid may be a sulfuric acid-containing liquid that contains sulfuric acid. [Brief description of the drawings]

[0018] [Figure 1] FIG. 1 is a schematic diagram showing an overall configuration of a substrate processing apparatus according to one embodiment of the present invention. [Diagram 2] FIG. 2 is a block diagram for explaining a configuration example relating to control of the substrate processing apparatus. [Figure 3A] FIG. 3A is a schematic diagram for explaining an operation example of the substrate processing apparatus. [Figure 3B] FIG. 3B is a schematic view for explaining an example of the operation of the substrate processing apparatus. [Figure 4A] FIG. 4A is a schematic cross-sectional view for explaining a structure in the vicinity of a surface of a substrate before the resist removal process is performed with a sulfuric acid-containing liquid in which ozone is dissolved. [Figure 4B] FIG. 4B is a schematic cross-sectional view for explaining the structure in the vicinity of the surface of the substrate after the resist removal process has been performed with the sulfuric acid-containing liquid in which ozone has been dissolved. [Diagram 5] FIG. 5 is a schematic view for explaining a first modified example of the substrate processing apparatus. [Figure 6] FIG. 6 is a schematic view for explaining a second modified example of the substrate processing apparatus. [Figure 7] FIG. 7 is a schematic view for explaining a third modified example of the substrate processing apparatus. [Figure 8] FIG. 8 is a schematic view for explaining a fourth modified example of the substrate processing apparatus. [Figure 9] FIG. 9 is a schematic view for explaining a fifth modified example of the substrate processing apparatus. [Figure 10] FIG. 10 is a schematic view for explaining a sixth modified example of the substrate processing apparatus. [Figure 11A] FIG. 11A is a schematic cross-sectional view for explaining a structure in the vicinity of a surface of a substrate before being subjected to a cleaning process with ammonia water having ozone dissolved therein. [Figure 11B]FIG. 11B is a schematic cross-sectional view for explaining the structure in the vicinity of the surface of the substrate after the cleaning process is performed with ammonia water in which ozone is dissolved. [Figure 12A] FIG. 12A is a schematic cross-sectional view for explaining a structure in the vicinity of a surface of a substrate before being subjected to a cleaning process with hydrofluoric acid in which ozone is dissolved. [Figure 12B] FIG. 12B is a schematic cross-sectional view for explaining the structure in the vicinity of the surface of the substrate after the cleaning process is performed with hydrofluoric acid in which ozone is dissolved. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. <Configuration of the substrate processing apparatus> FIG. 1 is a schematic diagram showing an overall configuration of a substrate processing apparatus 1 according to one embodiment of the present invention. The substrate processing apparatus 1 is a single-wafer processing apparatus that processes disk-shaped substrates W, such as semiconductor wafers, one by one. In this embodiment, the substrate processing apparatus 1 is configured to perform a resist removal process that peels off a resist layer 103 (see FIG. 4A described later) from the top surface (upper main surface) of the substrate W using a sulfuric acid ozone mixed liquid (SOM liquid), which is a mixed liquid of sulfuric acid and ozone gas.

[0020] The substrate processing apparatus 1 includes a substrate processing section 2 that processes substrates W with a sulfuric acid-containing liquid (processing liquid) having ozone gas dissolved therein, a recovery tank 3 that recovers the sulfuric acid-containing liquid discharged from the substrate processing section 2, a recovery piping 4 that connects the substrate processing section 2 and the recovery tank 3, a supply piping system 5 that supplies the sulfuric acid-containing liquid in the recovery tank 3 to the substrate processing section 2, an ozone gas piping 6 that supplies ozone gas to the supply piping system 5 and mixes the ozone gas with the sulfuric acid-containing liquid passing through the supply piping system 5, an ozone gas generator 7 that is connected to the ozone gas piping 6 and generates ozone gas, and a controller 8 (see FIG. 2 described later) that controls each component of the substrate processing apparatus 1.

[0021] The substrate processing unit 2 includes a box-shaped chamber 10 having an internal space, a spin chuck 11 (rotating holding member) that holds one substrate W in a horizontal position within the chamber 10 and rotates the substrate W about a vertical rotation axis A1 passing through the center of the substrate W, a sulfuric acid-containing liquid nozzle 12 that supplies a sulfuric acid-containing liquid to the upper surface of the substrate W held by the spin chuck 11, and a cylindrical processing cup 13 that surrounds the spin chuck 11. The sulfuric acid-containing liquid is a liquid that contains sulfuric acid, and is, for example, an aqueous sulfuric acid solution such as concentrated sulfuric acid.

[0022] An air blowing unit (not shown) for blowing clean air is provided on the upper wall of the chamber 10. An exhaust device (not shown) is connected to the processing cup 13 via an exhaust duct 14. The exhaust device sucks gas from inside the processing cup 13 through the bottom of the processing cup 13. An ozone decomposer 15 for decomposing ozone in the gas sucked in by the exhaust device is provided in the exhaust duct 14.

[0023] A clamping type chuck that horizontally clamps the substrate W and horizontally holds the substrate W is used as the spin chuck 11. Specifically, the spin chuck 11 includes a rotation drive member 16 such as a spin motor, a spin shaft 17 driven by the rotation drive member 16, and a disk-shaped spin base 18 attached to the upper end of the spin shaft 17 substantially horizontally. The spin base 18 includes a horizontal, circular upper surface 18a having an outer diameter larger than that of the substrate W. A plurality of (three or more, for example, six) clamping members 19 are disposed on the periphery of the upper surface 18a. The plurality of clamping members 19 are disposed at appropriate intervals on a circumference corresponding to the outer circumferential shape of the substrate W, on the periphery of the upper surface of the spin base 18.

[0024] The sulfuric acid-containing liquid nozzle 12 is, for example, a straight nozzle that ejects the sulfuric acid-containing liquid in a continuous flow state. The sulfuric acid-containing liquid nozzle 12 is moved horizontally by a nozzle moving mechanism 20. The nozzle moving mechanism 20 includes a nozzle arm 20A having the sulfuric acid-containing liquid nozzle 12 attached to its tip, and an arm moving mechanism 20B that moves the nozzle arm 20A to move the sulfuric acid-containing liquid nozzle 12 horizontally. The sulfuric acid-containing liquid nozzle 12 is attached to the nozzle arm 20A in a vertical position that ejects the sulfuric acid-containing liquid in a direction perpendicular to the upper surface of the substrate W. The nozzle arm 20A extends horizontally. The arm moving mechanism 20B includes an actuator such as an electric motor or an air cylinder.

[0025] The upstream end of the recovery pipe 4 is connected to the processing cup 13 of the substrate processing unit 2, and the downstream end of the recovery pipe 4 is connected to the recovery tank 3. The downstream end of the recovery pipe 4 is located above the liquid level of the sulfuric acid-containing liquid in the recovery tank 3. The recovery tank 3 has an internal space SP in contact with the liquid level of the sulfuric acid-containing liquid in the recovery tank 3. The substrate processing apparatus 1 further includes a recovery valve 21 for opening and closing the recovery pipe 4, a recovery filter 22 for removing impurities from the sulfuric acid-containing liquid passing through the recovery pipe 4, a recovery pipe heater 23 for heating the sulfuric acid-containing liquid in the recovery pipe 4, an exhaust pipe 24 for exhausting the internal space SP of the recovery tank 3, an ozone concentration meter 25 for measuring the ozone concentration in the internal space SP of the recovery tank 3, a recovery tank heater 26 for heating the sulfuric acid-containing liquid in the recovery tank 3, and a recovery side thermometer 27 for measuring the temperature of the sulfuric acid-containing liquid in the recovery tank 3.

[0026] The recovery valve 21 is disposed in the recovery pipe 4. The recovery filter 22 is disposed in the recovery pipe 4 downstream of the recovery valve 21. A position in the recovery pipe 4 that is heated by the recovery pipe heater 23 (recovery heating position 4a) is set downstream of the recovery filter 22. Although not shown, the recovery valve 21 includes a valve body provided with an internal flow path through which the liquid flows and an annular valve seat surrounding the internal flow path, a valve element movable relative to the valve seat, and an actuator that moves the valve element between a closed position in which the valve element contacts the valve seat and an open position in which the valve element is separated from the valve seat. Other valves described below have a similar configuration to the recovery valve 21.

[0027] The recovery pipe heater 23 heats the sulfuric acid-containing liquid passing through the recovery heating position 4a of the recovery pipe 4, for example, by heating the recovery heating position 4a from the outside. The recovery tank heater 26 may be a heater attached to the wall of the recovery tank 3 from the outer side, for example, as shown in FIG. 1. In FIG. 1, the recovery tank heater 26 is attached to the outer side of the side wall of the recovery tank 3, but it may be attached to the lower side of the bottom wall of the recovery tank 3, or it may be attached to both the bottom wall and the side wall. Unlike FIG. 1, the recovery tank heater 26 may be a heater immersed in the sulfuric acid-containing liquid in the recovery tank 3. Both the recovery pipe heater 23 and the recovery tank heater 26 are examples of heating members. Both the recovery pipe heater 23 and the recovery tank heater 26 may be called recovery side heaters.

[0028] The collection tank 3 is a tank with a closed top, and an internal space SP of the collection tank 3 is connected to the outside via an exhaust pipe 24. The ozone concentration meter 25 includes, for example, a measurement device main body 25A and a gas supply pipe 25B having a tip located in the internal space SP of the collection tank 3 and supplying gas in the internal space SP of the collection tank 3 to the measurement device main body 25A. The sulfuric acid-containing liquid discharged from the substrate processing unit 2 is heated by the recovery pipe heater 23 and the recovery tank heater 26. Therefore, the temperature of the sulfuric acid-containing liquid in the recovery tank 3 is maintained at a first temperature. The first temperature is, for example, 150° C. or higher and 200° C. or lower. The recovery tank heater 26 does not need to be operated all the time, and may be switched between a heating state and a non-heating state based on the temperature measured by the recovery side thermometer 27.

[0029] The supply piping system 5 includes a storage tank 30 for storing the sulfuric acid-containing liquid, an upstream supply piping 31 for sending the sulfuric acid-containing liquid from the recovery tank 3 to the storage tank 30, a downstream supply piping 32 to which the ozone gas piping 6 is connected and for supplying the sulfuric acid-containing liquid in the storage tank 30 toward the substrate processing unit 2, and a circulation piping 33 for circulating the sulfuric acid-containing liquid in the storage tank 30 by returning the sulfuric acid-containing liquid in the downstream supply piping 32 to the storage tank 30. The circulation piping 33 is branched and connected to the downstream supply piping 32.

[0030] The upstream end of the upstream supply pipe 31 is connected to the recovery tank 3, and the downstream end of the upstream supply pipe 31 is connected to the storage tank 30. The upstream end of the downstream supply pipe 32 is connected to the storage tank 30, and the downstream end of the downstream supply pipe 32 is connected to the sulfuric acid-containing liquid nozzle 12 of the substrate processing unit 2. The upstream end of the circulation pipe 33 is connected to the downstream supply pipe 32, and the downstream end of the downstream supply pipe 32 is connected to the storage tank 30.

[0031] The substrate processing apparatus 1 further includes an upstream liquid delivery pump 34 for delivering the sulfuric acid-containing liquid in the recovery tank 3 to the upstream supply piping 31, an upstream supply valve 35 for opening and closing the upstream supply piping 31, an upstream supply pump 36 for delivering the sulfuric acid-containing liquid in the storage tank 30 to the downstream supply piping 32, a downstream supply valve 37 for opening and closing the downstream supply piping 32, a downstream supply flow rate control valve 38 for adjusting the flow rate of the sulfuric acid-containing liquid in the downstream supply piping 32, and a circulation valve 39 interposed in the circulation piping 33 for opening and closing the circulation piping 33.

[0032] The upstream liquid delivery pump 34 is installed in the upstream supply pipe 31. The pump is a device that sucks in liquid and discharges the sucked liquid. Other pumps described below also have the same configuration as the upstream liquid delivery pump 34. The upstream supply valve 35 is disposed in the upstream supply piping 31 downstream of the upstream liquid feed pump 34. The upstream supply valve 35 is an example of a switching valve that switches between supplying and not supplying the sulfuric acid-containing liquid to the supply piping system 5.

[0033] The upstream supply pump 36 is provided in the downstream supply piping 32. The downstream supply flow rate control valve 38 is provided in the downstream supply piping 32 downstream of the upstream supply pump 36 and upstream of the connection position (circulation connection position 32a) of the circulation piping 33. The downstream supply valve 37 is provided in the downstream supply piping 32 downstream of the circulation connection position 32a. The substrate processing apparatus 1 further includes an ozone gas valve 40 for opening and closing the ozone gas pipe 6, and an ozone gas flow rate adjustment valve 41 for adjusting the flow rate of the ozone gas in the ozone gas pipe 6.

[0034] The ozone gas flow rate adjustment valve 41 is provided in the ozone gas pipe 6. The ozone gas valve 40 is provided in the ozone gas pipe 6 downstream of the ozone gas flow rate adjustment valve 41. The substrate processing apparatus 1 further includes a supply-side heater 50 as a temperature control member for adjusting the temperature of the sulfuric acid-containing liquid passing through the supply piping system 5 to a second temperature, and a supply-side thermometer 51 for measuring the temperature of the sulfuric acid-containing liquid in the supply piping system 5. The second temperature is a temperature lower than the first temperature, and is, for example, 80°C or higher and 130°C or lower.

[0035] The supply side heater 50 does not need to be operated all the time, and may be switched between a heated state and a non-heated state based on the temperature measured by the supply side thermometer 51. Since the second temperature is lower than the first temperature, by switching from the heated state to the non-heated state, it becomes easy to lower the temperature of the sulfuric acid-containing liquid in the supply piping system 5 and adjust it to the second temperature. In this embodiment, the supply side heater 50 heats the sulfuric acid-containing liquid in the downstream supply piping 32. The position (supply heating position 32b) in the downstream supply piping 32 that is heated by the supply side heater 50 is located upstream of the upstream supply pump 36 in the downstream supply piping 32.

[0036] The supply side heater 50 heats the sulfuric acid-containing liquid passing through the supply heating position 32b, for example, by externally heating the supply heating position 32b of the downstream supply pipe 32. Unlike this embodiment, the supply side heater 50 may be a heater that is immersed in the sulfuric acid-containing liquid in the storage tank 30 and heats the sulfuric acid-containing liquid in the storage tank 30, or may be attached to at least one of the outer surface of the side wall and the lower surface of the bottom wall of the storage tank 30. The supply side heater 50 may be a heater that heats the sulfuric acid-containing liquid in the circulation pipe 33. The supply side heater 50 and the temperature adjustment member may be a combination of these heaters.

[0037] The substrate processing apparatus 1 further includes a fluid mixer 60 provided at a position where the downstream supply pipe 32 and the ozone gas pipe 6 are connected, a refill pipe 70 for refilling the storage tank 30 with new sulfuric acid-containing liquid (new liquid) from a sulfuric acid-containing liquid supply source 75, and a drain pipe 80 connected to the recovery pipe 4 for discharging the sulfuric acid-containing liquid in the recovery pipe 4 to the outside of the substrate processing apparatus 1. The fluid mixer 60 is, for example, a static mixer that stirs and mixes the ozone gas and the sulfuric acid-containing liquid. The fluid mixer 60 is disposed in the downstream supply pipe 32 downstream of the downstream supply valve 37.

[0038] The substrate processing apparatus 1 further includes a refill valve 71 that is provided in the refill pipe 70 and opens and closes the refill pipe 70, and a drain valve 81 that is provided in the drain pipe 80 and opens and closes the drain pipe 80. The drain pipe 80 is connected to the recovery pipe 4 upstream of the recovery valve 21. 2 is a block diagram for explaining a configuration example regarding control of the substrate processing apparatus 1. The controller 8 includes a microcomputer, and controls the controlled objects included in the substrate processing apparatus 1 according to a predetermined control program.

[0039] Specifically, the controller 8 includes a processor (CPU) 8A and a memory 8B in which a control program is stored. The controller 8 is configured to execute various controls for substrate processing by the processor 8A executing the control program. In particular, the controller 8 is programmed to control the rotation drive member 16, the nozzle moving mechanism 20, the recovery piping heater 23, the recovery tank heater 26, the supply side heater 50, the recovery side thermometer 27, the supply side thermometer 51, the ozone concentration meter 25, the upstream liquid delivery pump 34, the upstream supply pump 36, the recovery valve 21, the upstream supply valve 35, the downstream supply valve 37, the downstream supply flow rate control valve 38, the circulation valve 39, the ozone gas valve 40, the ozone gas flow rate control valve 41, the refill valve 71, the drain valve 81, the ozone concentration meter 25, and the like.

[0040] In addition, the controller 8 also controls the operations of members provided in the substrate processing apparatus 1 according to each of the modified examples described below. <Operation example of substrate processing apparatus> Next, a description will be given of an operation example of the substrate processing apparatus 1. Figures 3A and 3B are schematic views for explaining an operation example of the substrate processing apparatus 1.

[0041] First, the substrate W is carried into the chamber 10 and held by the spin chuck 11 (substrate holding step). Then, as shown in FIG. 3A, the substrate W is rotated by the spin chuck 11 (substrate rotation step), and the sulfuric acid-containing liquid nozzle 12 is placed at the processing position. The processing position is, for example, a position where the sulfuric acid-containing liquid lands on the central region of the upper surface of the substrate W. With the sulfuric acid-containing liquid nozzle 12 placed at the processing position, the ozone gas valve 40 and the downstream supply valve 37 are opened. By opening the ozone gas valve 40 and the downstream supply valve 37, the sulfuric acid-containing liquid and ozone gas are mixed in the fluid mixer 60 (ozone gas mixing step).

[0042] The sulfuric acid-containing liquid and the ozone gas are mixed in the fluid mixer 60, whereby the ozone gas is dissolved in the sulfuric acid-containing liquid. The SOM liquid formed in the fluid mixer 60 is discharged from the sulfuric acid-containing liquid nozzle 12 and supplied onto the upper surface of the rotating substrate W (supply step). That is, the sulfuric acid-containing liquid in which ozone is dissolved is supplied from the supply piping system 5 to the substrate processing unit 2. As will be described in more detail later, a sulfuric acid-containing liquid in which ozone gas is dissolved is supplied to the upper surface of the substrate W, whereby the resist layer 103 (see FIG. 4A described later) is dissolved and the resist layer 103 is removed from the substrate W.

[0043] The recovery valve 21 is maintained in an open state while the sulfuric acid-containing liquid is being supplied to the upper surface of the substrate W. The sulfuric acid-containing liquid supplied to the upper surface of the substrate W is scattered toward the outside of the substrate W by centrifugal force caused by the rotation of the substrate W, and is received by the processing cup 13. The sulfuric acid-containing liquid received by the processing cup 13 is recovered in the recovery tank 3 via the recovery piping 4 (recovery process).

[0044] The sulfuric acid-containing liquid in which ozone is dissolved is heated by the recovery pipe heater 23 when passing through the recovery pipe 4. The sulfuric acid-containing liquid recovered in the recovery tank 3 is heated by the recovery tank heater 26. As a result, the temperature of the liquid in the recovery tank 3 becomes a first temperature. By heating the sulfuric acid-containing liquid, ozone dissolved in the sulfuric acid-containing liquid is generated as ozone gas, and the ozone concentration in the sulfuric acid-containing liquid is reduced. In this way, the sulfuric acid-containing liquid in the recovery tank 3 and the sulfuric acid-containing liquid passing through the recovery pipe 4 are heated so that the temperature of the sulfuric acid-containing liquid in the recovery tank 3 becomes the first temperature (heating process).

[0045] The ozone gas is generated from the sulfuric acid-containing liquid, and the ozone concentration in the internal space SP of the collection tank 3 increases. On the other hand, the ozone gas in the internal space SP is exhausted from the internal space SP through the exhaust pipe 24, and the ozone concentration in the internal space SP decreases. When the detected concentration of the ozone concentration meter 25 is smaller than the threshold value, it means that the ozone gas present in the internal space SP has been sufficiently reduced, and that the amount of ozone dissolved in the sulfuric acid-containing liquid in the collection tank 3 has been sufficiently reduced. Therefore, the controller 8 controls the upstream supply valve 35 based on the detection result (detected concentration) of the ozone concentration meter 25.

[0046] Specifically, the controller 8 closes the upstream supply valve 35 when the concentration detected by the ozone concentration meter 25 is higher than a predetermined threshold, and opens the upstream supply valve 35 when the concentration detected by the ozone concentration meter 25 is equal to or lower than the predetermined threshold. Therefore, when the heating temperature, heating time, etc. of the sulfuric acid-containing liquid are insufficient, the upstream supply valve 35 is closed as shown in Fig. 3A. When the recovery of the sulfuric acid-containing liquid has just started or when the recovery amount of the sulfuric acid-containing liquid is large, it is expected that the heating temperature, heating time, etc. of the sulfuric acid-containing liquid will be insufficient.

[0047] When the sulfuric acid-containing liquid is sufficiently heated and ozone is sufficiently removed from the sulfuric acid-containing liquid, the upstream supply valve 35 is opened as shown in Fig. 3B. By opening the upstream supply valve 35, the sulfuric acid-containing liquid in the recovery tank 3 is sent to the supply piping system 5 (liquid sending step). More specifically, the sulfuric acid-containing liquid in the recovery tank 3 is sent to the storage tank 30 via the upstream supply piping 31. The ozone concentration in the sulfuric acid-containing liquid flowing into the supply piping system 5 has been sufficiently reduced.

[0048] The sulfuric acid-containing liquid in the storage tank 30 is supplied to the sulfuric acid-containing liquid nozzle 12 via the downstream supply pipe 32. The sulfuric acid-containing liquid is adjusted by the supply side heater 50 while flowing through the downstream supply pipe 32 (temperature adjustment process). The sulfuric acid-containing liquid may be circulated by the circulation pipe 33. The sulfuric acid-containing liquid passes through the supply heating position 32b multiple times by being circulated by the circulation pipe 33. As a result, the sulfuric acid-containing liquid is heated multiple times by the supply side heater 50, and the temperature of the sulfuric acid-containing liquid is appropriately adjusted (circulation heating process). The temperature-adjusted sulfuric acid-containing liquid is mixed with ozone gas in the fluid mixer 60 on the way to the sulfuric acid-containing liquid nozzle 12 (ozone gas mixing process).

[0049] Unlike this embodiment, a mixed solution of sulfuric acid-containing solution and hydrogen peroxide water (SPM solution) can be used for the resist removal process. The hydrogen peroxide in the SPM solution is decomposed by the resist removal process to generate water. Therefore, in order to reuse the sulfuric acid-containing solution after the resist removal process, it is necessary to evaporate the water from the sulfuric acid-containing solution. However, the equipment for removing water from the SPM solution may be large-scale.

[0050] Therefore, in this embodiment, the resist removal process is performed using a sulfuric acid-containing liquid that contains ozone instead of hydrogen peroxide, so that the sulfuric acid-containing liquid can be reused without removing water. Furthermore, according to this embodiment, the sulfuric acid-containing liquid used in the resist removal process is heated to the first temperature in at least one of the recovery pipe 4 and the recovery tank 3. Therefore, ozone contained in the sulfuric acid-containing liquid is generated as ozone gas, and the ozone concentration in the sulfuric acid-containing liquid is reduced.

[0051] The sulfuric acid-containing liquid in the recovery tank 3 is supplied to the substrate processing unit 2 by the supply piping system 5. The sulfuric acid-containing liquid passing through the supply piping system 5 is mixed with ozone gas supplied from the ozone gas piping 6 to the supply piping system 5 before being supplied to the substrate processing unit 2. Therefore, the ozone gas is dissolved in the sulfuric acid-containing liquid, and the sulfuric acid-containing liquid with a sufficiently increased ozone concentration is supplied to the substrate processing unit 2. As described above, after intentionally removing ozone from the sulfuric acid-containing liquid used in the resist removal process, the sulfuric acid-containing liquid can be reused for the resist removal process by dissolving ozone gas in the sulfuric acid-containing liquid. Therefore, the sulfuric acid-containing liquid can be reused while accurately adjusting the ozone concentration in the sulfuric acid-containing liquid.

[0052] According to this embodiment, the temperature of the sulfuric acid-containing liquid passing through the supply piping system 5 is adjusted to a second temperature lower than the temperature (first temperature) of the sulfuric acid-containing liquid in the recovery tank 3. That is, after the sulfuric acid-containing liquid is heated to the first temperature to sufficiently reduce the ozone concentration in the sulfuric acid-containing liquid, the temperature of the sulfuric acid-containing liquid is adjusted to the second temperature. By mixing the ozone gas supplied from the ozone gas pipe 6 to the supply piping system 5 with the sulfuric acid-containing liquid whose temperature has been sufficiently reduced, the ozone gas can be dissolved in the sulfuric acid-containing liquid. In this way, after the ozone is sufficiently removed from the sulfuric acid-containing liquid, the ozone concentration in the sulfuric acid-containing liquid can be increased again. This allows the ozone concentration in the sulfuric acid-containing liquid supplied from the supply piping system 5 to the substrate processing unit 2 to be accurately adjusted.

[0053] Furthermore, since the temperature of the sulfuric acid-containing liquid in the supply piping system 5 is adjusted to a second temperature that is appropriately higher than room temperature (for example, 25° C.), the resist removal process can be appropriately performed on the substrates W in the substrate processing unit 2. According to this embodiment, the supply side heater 50 (temperature control member) is connected to the supply piping system 5 upstream of the ozone gas pipe 6. Therefore, before the ozone gas and the sulfuric acid-containing liquid supplied from the ozone gas pipe 6 to the supply piping system 5 are mixed, the temperature of the sulfuric acid-containing liquid is adjusted to the second temperature. Therefore, the ozone gas supplied to the supply piping system 5 can be quickly dissolved in the sulfuric acid-containing liquid.

[0054] According to this embodiment, the sulfuric acid-containing liquid, in which the ozone concentration has been reduced by being heated both in the recovery pipe 4 and in the recovery tank 3, can be stored in the storage tank 30. The sulfuric acid-containing liquid in the storage tank 30 is supplied toward the substrate processing unit 2 by the downstream supply pipe 32. Since the ozone gas pipe 6 is connected to the downstream supply pipe 32, the sulfuric acid-containing liquid is mixed with the ozone gas immediately before being supplied to the substrate processing unit 2. Therefore, it is possible to suppress the generation of ozone gas from the sulfuric acid-containing liquid and the reduction in the ozone concentration in the sulfuric acid-containing liquid during the period from when the sulfuric acid-containing liquid is mixed with the ozone gas to when it is supplied to the substrate processing unit 2. This makes it possible to precisely adjust the ozone concentration in the sulfuric acid-containing liquid supplied from the supply pipe system 5 to the substrate processing unit 2.

[0055] According to this embodiment, the ozone concentration in the sulfuric acid-containing liquid in the recovery tank 3 is directly or indirectly detected by the ozone concentration meter 25. Therefore, it is possible to determine whether or not ozone gas has been sufficiently removed from the sulfuric acid-containing liquid in the recovery tank 3 by heating with the recovery pipe heater 23 and the recovery tank heater 26. Furthermore, according to this embodiment, if the ozone concentration is higher than the threshold value, the upstream supply valve 35 (switching valve) is closed to prohibit the inflow of the sulfuric acid-containing liquid from the recovery tank 3 to the supply piping system 5. If the ozone concentration is equal to or lower than the threshold value, the upstream supply valve 35 is opened to allow the inflow of the sulfuric acid-containing liquid into the supply piping system 5. Therefore, only the sulfuric acid-containing liquid whose ozone concentration is equal to or lower than the threshold value can be automatically caused to flow into the supply piping system 5. Therefore, the ozone concentration in the sulfuric acid-containing liquid in the supply piping system 5 can be adjusted with even greater accuracy.

[0056] <Changes in structure near the substrate surface due to resist removal treatment> Next, a change in structure near the surface of the substrate W caused by the resist removal process will be described. Fig. 4A is a schematic cross-sectional view for explaining the structure in the vicinity of the surface of the substrate W before the resist removal process is performed with the sulfuric acid-containing liquid, and Fig. 4B is a schematic cross-sectional view for explaining the structure in the vicinity of the surface of the substrate W after the resist removal process is performed with the sulfuric acid-containing liquid.

[0057] 4A, the substrate W to be subjected to the resist removal process has, for example, a silicon layer 100 having a main surface 100a. The main surface 100a of the silicon layer 100 has a protected region 101 and an unprotected region 102. The substrate W has a resist layer 103 formed on the protected region 101 of the main surface 100a of the silicon layer 100, a first silicon oxide layer 104 formed on the protected region 101 of the main surface 100a, a first polysilicon layer 105 formed on the first silicon oxide layer 104, a second silicon oxide layer 106 formed on the unprotected region 102 of the main surface 100a, and a second polysilicon layer 107 formed on the second silicon oxide layer 106. The resist layer 103 covers the first silicon oxide layer 104 and the first polysilicon layer 105. The substrate W includes a first impurity region 108 of a first conductivity type (e.g., n-type) formed in a surface layer portion of the main surface 100a of the silicon layer 100 in the unprotected region 102, and a second impurity region 109 of the first conductivity type formed in the surface layer portion of the main surface 100a of the silicon layer 100 in the unprotected region 102, spaced apart from the first impurity region 108.

[0058] The second polysilicon layer 107 and the second silicon oxide layer 106 may form a planar gate structure formed on the main surface 100a of the silicon layer 100 so as to face a channel region of a second conductivity type (e.g., p-type) between the first impurity region 108 and the second impurity region 109. In this case, the first impurity region 108 and the second impurity region 109 function as a drain region and a source region, respectively.

[0059] As shown in FIG. 4B, the resist layer 103 is removed from the substrate W by performing the resist removal process using the sulfuric acid-containing liquid. If the ozone concentration in the sulfuric acid-containing liquid is too high, the surface layer of the silicon layer 100 in the unprotected region 102 is oxidized. Therefore, the surface layer of the first impurity region 108 and the second impurity region 109 is also oxidized, and an oxide film 110 is formed. By removing the oxide film 110 in the process performed after the resist removal process, the distance between the first polysilicon layer 105 as the gate and the surfaces of the first impurity region 108 and the second impurity region 109 increases, and the impurity concentrations of the first impurity region 108 and the second impurity region 109 are reduced. As a result, there is a risk of device failure. Specifically, there is a risk of a decrease in the drain current.

[0060] Therefore, if the ozone is intentionally removed from the sulfuric acid-containing liquid used in the resist removal process of the substrate W, and then ozone gas is dissolved in the sulfuric acid-containing liquid to reuse the sulfuric acid-containing liquid for the resist removal process of the substrate W, unintentional oxidation of the surface portion of the silicon layer 100 (the first impurity region 108 and the second impurity region 109) can be suppressed. <Modifications of the Substrate Processing Apparatus> 5 to 10 are schematic views for explaining first to sixth modified examples of the substrate processing apparatus 1, respectively.

[0061] 5, the substrate processing apparatus 1 according to the first modification includes a supply-side cooler 52 for cooling the sulfuric acid-containing liquid in the supply piping system 5, instead of the supply-side heater 50. The supply-side cooler 52 does not need to be operated all the time, and may be switched between a cooling state and a non-cooling state based on a temperature measured by a supply-side thermometer 51. Since the second temperature is lower than the first temperature, it becomes easy to lower the temperature of the sulfuric acid-containing liquid in the supply piping system 5 and adjust it to the second temperature by switching from the non-cooling state to the cooling state.

[0062] In this embodiment, the supply-side cooler 52 cools the sulfuric acid-containing liquid in the downstream supply piping 32. The position (supply cooling position 32c) in the downstream supply piping 32 where the liquid is cooled by the supply-side cooler 52 is located upstream of the upstream supply pump 36 in the downstream supply piping 32. Unlike this embodiment, the supply side cooler 52 may be a cooler that is immersed in the sulfuric acid-containing liquid in the storage tank 30 and cools the sulfuric acid-containing liquid in the storage tank 30, or may be attached to at least one of the outer surface of the side wall and the lower surface of the bottom wall of the storage tank 30. The supply side cooler 52 may be a cooler that cools the sulfuric acid-containing liquid in the circulation pipe 33. The supply side cooler 52 and the temperature adjustment member may be a combination of these coolers.

[0063] Unlike the first modified example, both the supply side heater 50 and the supply side cooler 52 may be provided. As shown in FIG. 6, in the substrate processing apparatus 1 according to the second modification, the supply piping system 5 does not include the storage tank 30 and the circulation piping 33, but includes a supply piping 90 in which the upstream supply piping 31 and the downstream supply piping 32 are integrated. The supply piping 90 supplies the sulfuric acid-containing liquid in the recovery tank 3 to the substrate processing unit 2. The substrate processing apparatus 1 according to the second modification further includes a liquid-transfer upstream supply pump 91 that sends the sulfuric acid-containing liquid in the recovery tank 3 to the supply piping 90, a supply-side cooler 52 that cools the sulfuric acid-containing liquid in the supply piping 90, a supply-side thermometer 51 that measures the temperature of the sulfuric acid-containing liquid in the supply piping system 5, a supply valve 92 that opens and closes the supply piping 90, and a supply flow rate adjustment valve 93 that adjusts the flow rate of the sulfuric acid-containing liquid in the supply piping 90. In the second modification, the supply valve 92 functions as a switching valve that switches between supplying and not supplying the sulfuric acid-containing liquid to the supply piping system 5.

[0064] As shown in FIG. 7, in the substrate processing apparatus 1 according to the third modification, the recovery pipe heater 23 is not provided, and the recovery tank heater 26 is provided as a recovery side heater. As shown in FIG. 8, in the substrate processing apparatus 1 according to the fourth modification, the recovery tank heater 26 is not provided, and the recovery pipe heater 23 is provided as a recovery side heater. In this manner, at least one of the recovery pipe heater 23 (heating member) that heats the sulfuric acid-containing liquid in the recovery pipe 4 to the first temperature and the recovery tank heater 26 (heating member) that heats the sulfuric acid-containing liquid in the recovery tank 3 to the first temperature may be provided. Similarly, in the heating step of the resist removal process, at least one of the sulfuric acid-containing liquid in the recovery tank 3 and the sulfuric acid-containing liquid passing through the recovery pipe 4 may be heated to the first temperature.

[0065] 9, in the substrate processing apparatus 1 according to the fifth modification, an ozone concentration meter 25 is configured to measure the ozone concentration in the sulfuric acid-containing liquid in the collection tank 3. In the fifth modification, the ozone concentration meter 25 includes a measurement device main body 25A and a liquid supply pipe 25C having a tip located below the liquid level of the sulfuric acid-containing liquid in the collection tank 3 and supplying the sulfuric acid-containing liquid in the collection tank 3 to the measurement device main body 25A.

[0066] As shown in FIG. 10, in a substrate processing apparatus 1 according to the sixth modified example, a plurality of recovery tanks 3 (two in this embodiment) are arranged in parallel. The multiple collection tanks 3 include a first collection tank 3A and a second collection tank 3B. The first collection tank 3A and the second collection tank 3B have the same configuration. That is, the exhaust pipe 24, the ozone concentration meter 25, the collection tank heater 26, and the collection side thermometer 27 are provided in both the first collection tank 3A and the second collection tank 3B.

[0067] The upstream end of the recovery pipe 4 is connected to a processing cup 13 (see FIG. 1) of the substrate processing unit 2, and the downstream end of the recovery pipe 4 is connected to a first recovery tank 3A. The upstream end of the upstream supply pipe 31 is connected to the first recovery tank 3A, and the downstream end of the upstream supply pipe 31 is connected to a storage tank 30 (see FIG. 1). The substrate processing apparatus 1 of the sixth modified example further includes a downstream recovery valve 94 that opens and closes the recovery pipe 4 downstream of the recovery valve 21, a branch recovery pipe 95 that branches off from the recovery pipe 4 and is connected to a second recovery tank 3B, and a branch supply pipe 96 that branches off from the upstream supply pipe 31 and is connected to the second recovery tank 3B.

[0068] The downstream recovery valve 94 is disposed in the recovery pipe 4 downstream of the recovery pipe heater 23. A branch connection position 4b in the recovery pipe 4 to which the branch recovery pipe 95 is connected is a position downstream of the recovery pipe heater 23 and upstream of the downstream recovery valve 94. A branch connection position 31a in the upstream supply pipe 31 to which the branch supply pipe 96 is connected is a position downstream of the upstream supply valve 35.

[0069] The substrate processing apparatus 1 according to the sixth modified example includes a branch recovery valve 97 for opening and closing the branch recovery pipe 95, a branch liquid feed pump 98 for feeding the sulfuric acid-containing liquid in the second recovery tank 3B to the branch supply pipe 96, and a branch supply valve 99 for opening and closing the branch supply pipe 96. The branch recovery valve 97 is provided in the branch recovery pipe 95. The branch liquid feed pump 98 is provided in the branch supply pipe 96, and the branch supply valve 99 is provided in the branch supply pipe 96 downstream of the branch liquid feed pump 98.

[0070] In a configuration in which multiple collection tanks 3 are arranged in parallel, if the ozone concentration in the sulfuric acid-containing liquid in at least one of the two collection tanks 3 is sufficiently reduced, the sulfuric acid-containing liquid can be sent toward the storage tank 30. <Treatment with liquids other than those containing sulfuric acid> The processing liquid supplied to the upper surface of the substrate W is not limited to a sulfuric acid-containing liquid, but may be ammonia water or hydrofluoric acid (hydrogen fluoride water). By dissolving ozone gas in ammonia water, an ammonia water ozone mixed liquid (AOM liquid) suitable for cleaning processing can be formed. By dissolving ozone gas in hydrofluoric acid, a hydrofluoric acid ozone mixed liquid (FOM liquid) suitable for cleaning processing after dry etching can be formed.

[0071] Fig. 11A is a schematic cross-sectional view for explaining the structure in the vicinity of the surface of the substrate W before cleaning processing with ammonia water having ozone dissolved therein, and Fig. 11B is a schematic cross-sectional view for explaining the structure in the vicinity of the surface of the substrate W after cleaning processing with ammonia water having ozone dissolved therein. 11A, a substrate W to be subjected to a cleaning process using ammonia water having ozone dissolved therein includes, for example, a silicon layer 100 having a main surface 100a, a silicon oxide layer 111 formed on the main surface 100a, a polysilicon layer 112 formed on the silicon oxide layer 111, an interlayer insulating film 113 formed on the main surface 100a and covering the silicon oxide layer 111 and the polysilicon layer 112, and a contact electrode 115 embedded in a contact hole 114 formed in the interlayer insulating film 113. The interlayer insulating film 113 is formed of, for example, at least one of silicon oxide and silicon nitride. The contact electrode 115 is, for example, a metal such as tungsten.

[0072] By performing a cleaning process using ammonia water in which ozone is dissolved, foreign matter adhering to the surface of interlayer insulating film 113 is washed away. If the ozone concentration in the ammonia water is too high, contact electrode 115 exposed from interlayer insulating film 113 is etched as shown in FIG. 11B. The surface of contact electrode 115 is recessed by etching, which may result in the formation of unintended recess 116. The formation of recess 116 may cause device defects.

[0073] Therefore, if ozone is intentionally removed from the ammonia water used in the cleaning process of the substrate W and then ozone gas is dissolved in the ammonia water, the ammonia water can be reused for the cleaning process. This makes it possible to suppress the unintended formation of recesses 116 on the main surface of the substrate W. Fig. 12A is a schematic cross-sectional view for explaining the structure in the vicinity of the surface of the substrate W before cleaning with hydrofluoric acid having ozone dissolved therein, and Fig. 12B is a schematic cross-sectional view for explaining the structure in the vicinity of the surface of the substrate W after cleaning with hydrofluoric acid having ozone dissolved therein.

[0074] 12A, the substrate W to be cleaned with hydrofluoric acid having ozone dissolved therein is, for example, a substrate W after an interlayer insulating film has been removed by dry etching. The substrate W to be cleaned with hydrofluoric acid having ozone dissolved therein specifically includes a silicon layer 100 having a main surface 100a, a protrusion 120 protruding from the main surface 100a of the silicon layer 100, a pad oxide layer 121 formed on a top portion 120a of the protrusion 120, and a nitride layer 122 formed on the pad oxide layer 121. The protrusion 120 is made of silicon.

[0075] Damage caused by dry etching is removed by performing a cleaning process using hydrofluoric acid in which ozone is dissolved. If the ozone concentration in the hydrofluoric acid in which ozone is dissolved is too high, the sidewall 120b of the protrusion 120 is etched as shown in FIG. 12B. The width of the protrusion 120 is narrowed by etching, which may cause device failure. Therefore, if ozone gas is dissolved in the hydrofluoric acid after intentionally removing ozone from the hydrofluoric acid used in the cleaning process of the substrate W, the hydrofluoric acid can be reused for the cleaning process. This makes it possible to suppress unintended etching of the protrusions 120 on the main surface of the substrate W.

[0076] <Other embodiments> The present invention is not limited to the above-described embodiment, and can be embodied in other forms. For example, in the embodiment shown in FIG. 1, the circulation valve 39 may be disposed in the downstream supply pipe 32 upstream of the circulation connection position 32a.

[0077] In the above-described embodiment, the ozone gas and the sulfuric acid-containing liquid are mixed using the fluid mixer 60. However, unlike the above-described embodiment, instead of the fluid mixer 60, a bubbling mechanism for bubbling the ozone gas in a tank for storing the sulfuric acid-containing liquid to dissolve the ozone gas in the sulfuric acid-containing liquid may be provided. In this case, the ozone gas pipe 6 is connected to the downstream supply pipe 32 without passing through the fluid mixer 60.

[0078] In the above embodiment, the supply heating position 32b (see FIG. 1) is set upstream of the connection position (fluid mixer 60) of the ozone gas pipe 6 in the downstream supply pipe 32. However, the supply heating position 32b may be provided downstream of the fluid mixer 60 in the downstream supply pipe 32. In the above embodiment, the controller 8 closes the upstream supply valve 35 when the concentration detected by the ozone concentration meter 25 is higher than a predetermined threshold, and opens the upstream supply valve 35 when the concentration detected by the ozone concentration meter 25 is equal to or lower than the predetermined threshold. However, the controller 8 may control the upstream supply valve 35 to open the upstream supply valve 35 when the detected concentration is 0 ppm, and to close the upstream supply valve 35 when the detected concentration is greater than 0 ppm.

[0079] In the above-described embodiment, the substrate processing apparatus 1 is a single-wafer processing apparatus that processes one substrate W at a time. However, the substrate processing apparatus 1 may be an immersion processing apparatus that processes a plurality of substrates W by immersing them in a processing liquid stored in an immersion tank. In the above embodiment, expressions such as "horizontal" and "vertical" are used. However, it is not necessary for the object to be strictly "horizontal" or "vertical." In other words, these expressions allow for deviations due to manufacturing precision, installation precision, and the like.

[0080] In addition, various modifications can be made within the scope of the claims. [Explanation of symbols]

[0081] 1: Substrate processing equipment 2: Substrate processing section 3: Collection tank 3A: First collection tank 3B: Second collection tank 4: Recovery piping 5: Supply piping system 6: Ozone gas piping 8: Controller 23: Recovery pipe heater (heating element) 25: Ozone concentration meter 26: Recovery tank heater (heating element) 30: Storage tank 31: Upstream supply pipe 32: Downstream supply pipe 35: Upstream supply valve (switching valve) 50: Supply side heater (temperature control component) 52: Supply side cooler (temperature control component) 60:Fluid mixer 92: Supply valve (switching valve) 100: Silicon layer 100a: Main surface 101 :Protected area 103: Resist layer SP: Internal space W: Substrate

Claims

1. a substrate processing section for processing substrates with a processing liquid having ozone dissolved therein; a recovery tank for recovering the processing liquid discharged from the substrate processing unit; a recovery pipe connecting the substrate processing unit and the recovery tank; a heating member that heats at least one of the treatment liquid in the recovery pipe and the treatment liquid in the recovery tank to a first temperature to reduce an ozone concentration in the treatment liquid; a supply piping system that supplies the processing liquid in the recovery tank to the substrate processing unit; the substrate processing apparatus comprising an ozone gas pipe that supplies ozone gas to the supply piping system and mixes the ozone gas with the processing liquid having a reduced ozone concentration that passes through the supply piping system.

2. A substrate processing section for processing substrates with a processing liquid having ozone dissolved therein; a recovery tank for recovering the processing liquid discharged from the substrate processing unit; a recovery pipe connecting the substrate processing unit and the recovery tank; a heating member including at least one of a recovery pipe heater that heats the treatment liquid in the recovery pipe in the recovery pipe and a recovery tank heater that heats the treatment liquid in the recovery tank in the recovery tank, the heating member heating the treatment liquid to a first temperature; a supply piping system that supplies the processing liquid in the recovery tank to the substrate processing unit; The substrate processing apparatus includes an ozone gas pipe that supplies ozone gas to the supply piping system and mixes the ozone gas with the processing liquid passing through the supply piping system.

3. The substrate processing apparatus according to claim 1 , further comprising a temperature adjusting member that adjusts a temperature of the processing liquid passing through the supply piping system to a second temperature that is lower than the first temperature.

4. The first temperature is a temperature of 150° C. or more and 200° C. or less, The substrate processing apparatus of claim 3 , wherein the second temperature is a temperature not lower than 80° C. and not higher than 130° C.

5. 5. The substrate processing apparatus according to claim 3, wherein the temperature control member is connected to an upstream side of the ozone gas pipe in the supply piping system.

6. 6. The substrate processing apparatus according to claim 1, wherein the processing liquid is a sulfuric acid-containing liquid.

7. 7. The substrate processing apparatus according to claim 6, wherein the substrate comprises a silicon layer having a main surface, and a resist layer formed on a protection region of the main surface of the silicon layer and removable with the sulfuric acid-containing liquid in which ozone is dissolved.

8. 8. The substrate processing apparatus according to claim 1, wherein the supply piping system includes a storage tank for storing the processing liquid, an upstream supply piping for transporting the processing liquid from the recovery tank to the storage tank, and a downstream supply piping to which the ozone gas piping is connected and which supplies the processing liquid in the storage tank toward the substrate processing apparatus.

9. The substrate processing apparatus according to claim 1 , further comprising an ozone concentration meter for measuring an ozone concentration in the processing liquid in the recovery tank or an ozone concentration in a space in contact with a liquid surface of the processing liquid in the recovery tank.

10. a switching valve for switching between an inflow and an outflow of the treatment liquid from the recovery tank to the supply piping system; A controller that controls the switching valve based on a detection result of the ozone concentration meter is further provided.

10. The substrate processing apparatus according to claim 9, wherein the controller opens the switching valve when the concentration detected by the ozone concentration meter is equal to or lower than a predetermined threshold, and closes the switching valve when the concentration detected by the ozone concentration meter is higher than the predetermined threshold.

11. a supply step of supplying a processing liquid from a supply piping system to a substrate processing section for processing substrates with the processing liquid having ozone dissolved therein; a recovery step of recovering the processing liquid from the substrate processing section into a recovery tank via a recovery pipe; a heating step of heating at least one of the treatment liquid in the recovery tank and the treatment liquid passing through the recovery pipe to a first temperature; a liquid sending step of sending the treatment liquid heated by the heating step to the supply piping system; a temperature adjusting step of adjusting a temperature of the treatment liquid in the supply piping system to a second temperature lower than the first temperature; an ozone gas mixing step of mixing ozone gas with the processing liquid in the supply piping system whose temperature has been adjusted in the temperature adjusting step.

12. The first temperature is a temperature of 150° C. or more and 200° C. or less, The method of claim 11 , wherein the second temperature is a temperature not lower than 80° C. and not higher than 130° C.

13. The substrate processing method according to claim 11 or 12, wherein the processing liquid is a sulfuric acid-containing liquid.

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