Substrate processing method and substrate processing apparatus

Abstract

To provide a substrate processing method and a substrate processing apparatus that can improve the removal rate of chuck marks.SOLUTION: A substrate processing method includes: a substrate rotation step of rotating a substrate W made of silicon in a horizontal position; a mixed chemical liquid discharging step of discharging a mixed chemical liquid of hydrofluoric acid and ozone water from a chemical liquid nozzle 51 onto the back surface of the rotated substrate W; a polishing tool pressing step of pressing a polishing tool 31 having a resin body in which abrasive grains are dispersed against the back surface of the rotating substrate W while discharging a rinsing liquid from the fixed nozzle 3 onto the back surface of the rotated substrate W after the mixed chemical liquid discharging step; and a polishing tool moving step of moving the polishing tool 31 between the center of the substrate W and the edge of the substrate W while performing the polishing tool pressing step.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a substrate processing method and a substrate processing apparatus for processing substrates. Examples of substrates include semiconductor substrates, FPD (Flat Panel Display) substrates, photomask glass substrates, optical disk substrates, magnetic disk substrates, ceramic substrates, and solar cell substrates. Examples of FPDs include liquid crystal display devices and organic EL (electroluminescence) display devices. [Background technology]

[0002] Conventional substrate processing apparatuses include a holding and rotating unit that rotates a substrate held in a horizontal position, a brush arm, a chemical arm, and a pure water nozzle that dispenses pure water (see, for example, Patent Documents 1 and 2). The brush arm includes a brush that comes into contact with the surface of the substrate to perform brush cleaning. The chemical arm also includes a chemical nozzle that dispenses chemical liquid.

[0003] Patent Document 3 discloses a cylindrical polishing head formed of, for example, a PVA (polyvinyl alcohol) sponge with dispersed abrasive grains. Patent Document 4 discloses that a synthetic grinding stone in which an abrasive (abrasive grains) is fixed with a resin binder is used to perform surface processing by dry chemical mechanical grinding. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-183711 [Patent Document 2] Japanese Patent Application Laid-Open No. 2017-175062 [Patent Document 3] Japanese Patent Application Publication No. 2018-046109 [Patent Document 4] Patent No. 6779540 Summary of the Invention [Problem to be solved by the invention]

[0005] However, conventional substrate processing apparatuses have the following problems. In recent years, there has been a problem of defocus (so-called out-of-focus) in EUV (Extreme Ultraviolet) exposure machines due to the substrate flatness of the backside of a substrate (e.g., a wafer). One of the causes of poor flatness is chuck marks that are attached (formed) when the backside of the substrate is attracted to the chuck. There are two main types of chuck marks. The first is a scratch or pit that occurs when a particle such as metal dust is sandwiched between the substrate and the chuck. The second is a particle that firmly adheres to the substrate W by sinking into the substrate W when sandwiched between the substrate and the chuck. Conventional cleaning methods have a problem in that they have a low removal rate for such chuck marks.

[0006] In Patent Documents 1 and 2, a FOM (Fiber-Oxide Mixture) made of a mixture of hydrofluoric acid solution and ozone water is ejected onto a substrate, and then brush cleaning is performed while supplying deionized water (DIW) to the substrate. The brush uses a sponge-like scrubbing member made of PVA (polyvinyl alcohol). However, even with this method, the rate of chucking marks removal may be low.

[0007] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a substrate processing method and a substrate processing apparatus that can improve the removal rate of chuck marks. [Means for solving the problem]

[0008] In order to achieve the above object, the present invention has the following configuration: That is, the substrate processing method according to the present invention includes a substrate rotation step of rotating a horizontally oriented silicon substrate, a mixed chemical discharge step of discharging a mixed chemical solution of hydrofluoric acid and ozone water from a chemical solution nozzle onto the back surface of the rotated substrate, a polishing tool pressing step of pressing a polishing tool having a resin body in which abrasive grains are dispersed against the back surface of the rotated substrate after the mixed chemical solution discharge step while discharging a rinse solution from a rinse solution nozzle onto the back surface of the rotated substrate, and a polishing tool moving step of moving the polishing tool between the center of the substrate and an edge of the substrate while performing the polishing tool pressing step. a second mixed chemical solution discharge step of again discharging the mixed chemical solution from the chemical solution nozzle onto the rear surface of the substrate being rotated after the polishing tool pressing step and the polishing tool moving step; The present invention is characterized by the following features.

[0009] According to the substrate processing method of the present invention, when a mixed chemical (FOM) is discharged onto the backside of the substrate, silicon is oxidized by ozone water, and an oxide film (SiO) is etched by hydrofluoric acid. This makes it possible to remove fine scratches and dents formed on the backside of the substrate. Furthermore, the mixed chemical etches the periphery of particles firmly attached to the backside of the substrate, making the particles easier to peel off. Thereafter, the backside of the substrate is actively polished (ground) by a polishing tool. This makes it even easier to peel off particles from the backside of the substrate. This improves the removal rate of chucking marks formed on the substrate.

[0010] Furthermore, the mixed chemical solution can improve the surface roughness of the rear surface of the substrate, thereby reducing the burden of polishing to remove scratches and other imperfections left by etching with the mixed chemical solution.

[0011] Furthermore, the above-described substrate processing method preferably further includes a second mixed chemical discharge step of again discharging the mixed chemical from the chemical nozzle onto the back surface of the rotating substrate after the polishing tool pressing step and the polishing tool moving step. The polishing process can remove chucking marks on the back surface of the substrate, but scratches caused by the polishing tool may remain. Therefore, by discharging the mixed chemical onto the back surface of the substrate after the polishing process (the polishing tool pressing step and the polishing tool moving step), scratches caused by the polishing tool can be removed.

[0012] Furthermore, in the second chemical mixture discharge step of the above-described substrate processing method, it is preferable to move the chemical mixture nozzle between above the center of the substrate and above the edge of the substrate while the chemical mixture is being discharged from the chemical mixture nozzle. While this can remove scratches caused by the polishing tool, if the chemical mixture nozzle continues to deposit the chemical mixture at the same position on the back surface of the substrate, there is a possibility that etching will progress too far at that position. Therefore, by moving the position of the chemical mixture, localized etching can be prevented on the back surface of the substrate planarized by the polishing process.

[0013] Further, a substrate processing apparatus according to the present invention includes a holding and rotating unit that holds and rotates a horizontally oriented substrate made of silicon, a chemical solution nozzle that discharges a mixed chemical solution of hydrofluoric acid and ozone water, a rinse liquid nozzle that discharges a rinse liquid, a polishing tool having a resin body in which abrasive grains are dispersed, a polishing tool moving mechanism that moves the polishing tool, and a control unit, wherein the control unit rotates the substrate using the holding and rotating unit, the control unit discharges the mixed chemical solution from the chemical solution nozzle onto a back surface of the rotated substrate, and after discharging the mixed chemical solution, the control unit presses the polishing tool against the back surface of the rotated substrate using the polishing tool moving mechanism while discharging rinse liquid from the rinse liquid nozzle onto the back surface of the rotated substrate, and while pressing the polishing tool against the back surface of the rotated substrate, the control unit further moves the polishing tool between the center of the substrate and an edge of the substrate using the polishing tool moving mechanism. The control unit presses the polishing tool against the rear surface of the substrate being rotated, moves the polishing tool, and then discharges the mixed chemical solution from the chemical solution nozzle onto the rear surface of the substrate being rotated again. It is characterized by the above. [Effects of the Invention]

[0014] According to the substrate processing method and substrate processing apparatus of the present invention, the removal rate of chuck marks can be improved. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a diagram showing a schematic configuration of a substrate processing apparatus according to a first embodiment. [Figure 2] 1 is a plan view of a substrate processing apparatus according to a first embodiment. [Figure 3] 4 is a flowchart illustrating the operation of the substrate processing apparatus according to the first embodiment. [Figure 4] (a) is a plan view for explaining the FOM ejection process, (b) is a side view of (a), (c) is a plan view for explaining the ozone water ejection process, (d) is a side view of (c), (e) is a plan view for explaining the rinsing process, and (f) is a side view of (e). [Figure 5] FIG. 2 is a side view showing the path of movement of the grinding tool during repeated grinding processes. [Figure 6] 10(a) to 10(e) are diagrams illustrating the removal of chucking marks formed on the rear surface of a substrate. [Figure 7] 10 is a flowchart illustrating the operation of the substrate processing apparatus according to the second embodiment. [Figure 8] FIG. 10 is a diagram showing the film thickness of a substrate before and after etching processing by FOM. [Figure 9] FIG. 10 is a side view illustrating the operation of moving the chemical nozzle while discharging the FOM from the chemical nozzle in the second FOM discharging step of the modified example. Example 1

[0016] A first embodiment of the present invention will be described below with reference to the drawings. Fig. 1 is a diagram showing a schematic configuration of a substrate processing apparatus according to the first embodiment. Fig. 2 is a plan view of the substrate processing apparatus according to the first embodiment.

[0017] (1) Configuration of the substrate processing apparatus 1 See Figures 1 and 2. The substrate processing apparatus 1 includes a holding and rotating unit 2, a fixed nozzle 3, a polishing arm 5, and a chemical arm 7. The holding and rotating unit 2 holds and rotates a substrate W in a horizontal position. The substrate (silicon substrate) W is made of silicon (Si) and is formed in a disk shape. In this embodiment, the diameter of the substrate W is, for example, 300 mm, but is not limited to this size.

[0018] The holding and rotating unit 2 includes a spin chuck 9, a rotating shaft 11, and a rotation drive unit 13. The rotation drive unit 13 includes an electric motor. The rotation drive unit 13 rotates the spin chuck 9 around a vertical axis AX1 via the rotating shaft 11.

[0019] The spin chuck 9 includes a spin base 15 and three or more (e.g., six) holding pins 17. The spin base 15 is formed in a disk shape. A vertical axis AX1 passes through the center of the spin base 15. The three or more holding pins 17 are arranged in a ring shape at equal intervals around the vertical axis AX1. Some or all of the three or more holding pins 17 are configured to be movable. The movable holding pins 17 rotate around the vertical axis passing through them. As a result, the spin chuck 9 holds the substrate W by sandwiching the side surfaces of the substrate W between the three or more holding pins 17. The spin chuck 9 may also be configured to hold the substrate W by suctioning the underside of the substrate W.

[0020] The holding and rotating unit 2 includes a gas discharge port 19, a gas supply pipe 21, a gas piping 23, a gas supply source 25, and an on-off valve V1. The gas discharge port 19 has a ring-shaped slit and discharges gas in almost all horizontal directions from the vertical axis AX1. The gas supply pipe 21 delivers gas to the gas discharge port 19. The gas supply pipe 21 is provided so as to penetrate the rotary shaft 11 and the rotary drive unit 13 along the vertical axis AX1.

[0021] The gas pipe 23 sends gas (for example, an inert gas such as nitrogen) from a gas supply source 25 to the gas supply pipe 21. An on-off valve V1 is provided in the gas pipe 23. When the on-off valve V1 is open, gas is discharged from the gas discharge port 19. When the on-off valve V1 is closed, the discharge of gas from the gas discharge port 19 is stopped. The gas discharge port 19 discharges gas in the gap between the substrate W and the spin base 15 so that the gas flows from the center of the substrate W to the edge (outer edge) of the substrate W.

[0022] The fixed nozzle 3 ejects pure water (rinse liquid) obliquely downward onto the upper surface of the substrate W. For example, deionized water (DIW) is used as the pure water. The fixed nozzle 3 is provided at a fixed position off-center of the substrate W. The fixed position of the fixed nozzle 3 is a position that does not interfere with the movement of the polishing tool 31 and the chemical nozzle 51, which will be described later. In this embodiment, the fixed nozzle 3 is provided outside the substrate W held by the holding and rotating unit 2. As shown in FIG. 2 , the fixed nozzle 3 is provided between a polishing tool rotating mechanism 41 and a nozzle rotating mechanism 57, which will be described later. The fixed nozzle 3 is configured not to move horizontally, but may be movable horizontally. The fixed nozzle 3 may also be configured not to rotate around a predetermined vertical axis or to move up and down. The fixed nozzle 3 corresponds to the rinse liquid nozzle of the present invention.

[0023] The tip of a pure water pipe 27 is connected to the fixed nozzle 3. The base of the pure water pipe 27 is connected to a pure water supply source 29. The pure water pipe 27 sends pure water from the pure water supply source 29 to the fixed nozzle 3. An on-off valve V2 is provided on the pure water pipe 27. When the on-off valve V2 is open, pure water is discharged from the fixed nozzle 3. When the on-off valve V2 is closed, the discharge of pure water from the fixed nozzle 3 is stopped.

[0024] The polishing arm 5 is a mechanism for polishing the rear surface (upper surface) of the substrate W. The polishing arm 5 includes a polishing tool 31, a shaft 33, a polishing arm body 35, and an electric motor 37. The polishing tool 31 is also called a brush or a polishing brush.

[0025] The polishing tool 31 polishes the back surface of a substrate by surface chemical action or a method called chemical mechanical grinding (CMG). The polishing tool 31 is formed in a cylindrical shape. The polishing tool 31 has a resin body in which abrasive grains (abrasive material) are dispersed. That is, the polishing tool 31 is formed by fixing the abrasive grains with a resin binder. For example, the polishing tool 31 has PVA in which silicon carbide (SiC) is dispersed as abrasive grains.

[0026] The polishing tool 31 may also be as follows: For example, oxides such as cerium oxide (CeO2) or silica (SiO2) may be used as abrasive grains. The average particle size of the abrasive grains is preferably 10 μm or less. For example, thermosetting resins such as epoxy resins or phenolic resins may be used as the resin body (resin binder). For example, thermoplastic resins such as ethyl cellulose may be used as the resin body. In this case, polishing is performed so as not to soften the thermoplastic resin.

[0027] Here, we will explain chemical mechanical grinding (CMG). CMG is thought to work according to the following principle: When abrasive grains such as cerium oxide come into contact with the workpiece, localized high temperatures and pressures are generated near the abrasive grains, causing a solid-phase reaction between the abrasive grains and the workpiece, producing silicates. As a result, the surface layer of the workpiece becomes soft, and the softened surface layer is mechanically removed by the abrasive grains.

[0028] Returning to the explanation of the polishing arm 5, the upper end of the polishing tool 31 is attached to the lower end of a shaft 33 extending vertically. The upper part of the shaft 33 is held by a polishing arm main body 35 extending horizontally so as to be rotatable about a vertical axis AX2. The shaft 33 is rotated about the vertical axis AX2 by an electric motor 37, for example, via a belt or gear. The polishing tool 31 and the shaft 33 are provided on the tip side of the polishing arm main body 35.

[0029] The polishing arm 5 further includes a lifting mechanism (linear actuator) 39 and a polishing tool rotating mechanism 41. The lifting mechanism 39 raises and lowers the polishing tool 31, the polishing arm main body 35, etc. The lifting mechanism 39 includes a guide rail 43 and a drive unit 45. The base end of the polishing arm main body 35 is supported by the guide rail 43 so that it can be raised and lowered. The guide rail 43 guides the polishing arm main body 35 in the up and down direction. The drive unit 45 includes, for example, an electric motor and a screw shaft.

[0030] The drive unit 45 may include an air cylinder and an electro-pneumatic regulator instead of an electric motor, etc. The electro-pneumatic regulator supplies gas such as air at a pressure set based on an electric signal from a control unit 71 (described later) to the air cylinder.

[0031] The polishing tool rotating mechanism 41 is provided outside the substrate W held by the holding and rotating unit 2. The polishing tool rotating mechanism 41 rotates the polishing tool 31, the polishing arm body 35, the lifting mechanism 39, etc. around a vertical axis AX3. The polishing tool rotating mechanism 41 is equipped with an electric motor. As shown in FIG. 2, the standby position of the polishing tool 31 is a position in the +Y direction of the polishing tool rotating mechanism 41. The lifting mechanism 39 and the polishing tool rotating mechanism 41 correspond to the polishing tool moving mechanism of the present invention.

[0032] The chemical arm 7 includes a chemical nozzle 51, an arm body 53, a rotating shaft 55, and a nozzle rotating mechanism 57. The chemical nozzle 51 discharges the chemical downward onto the upper surface of the substrate W. The chemical nozzle 51 selectively discharges, for example, FOM, ozone water (O3), and pure water. The FOM is a mixed chemical of hydrofluoric acid (HF) and ozone water (O3). The ratio of hydrofluoric acid to ozone water in the FOM is 1:7.

[0033] The tip of chemical piping 59 is connected to the chemical nozzle 51. The base of chemical piping 59 is connected to an FOM supply source 61. The chemical piping 59 sends FOM from the FOM supply source 61 to the chemical nozzle 51. An on-off valve V3 is provided in the chemical piping 59. When on-off valve V3 is open and on-off valves V4 and V5, which will be described later, are closed, FOM is discharged from the chemical nozzle 51. When on-off valve V3 is closed, the discharge of FOM from the chemical nozzle 51 is stopped.

[0034] The tip of ozone water piping 63 is connected to chemical liquid piping 59 between chemical liquid nozzle 51 and on-off valve V3. The base end of ozone water piping 63 is connected to ozone water supply source 65. Ozone water piping 63 sends ozone water from ozone water supply source 65 to chemical liquid nozzle 51 via chemical liquid piping 59. On-off valve V4 is provided on ozone water piping 63. On-off valve V4 starts and stops the discharge of ozone water from chemical liquid nozzle 51.

[0035] The tip of the second pure water pipe 66 is connected to the chemical liquid pipe 59 between the chemical liquid nozzle 51 and the on-off valve V3. The base of the second pure water pipe 66 is connected to a second pure water supply source 68. The second pure water pipe 66 sends pure water (e.g., DIW) from the second pure water supply source 68 to the chemical liquid nozzle 51 via the chemical liquid pipe 59. An on-off valve V5 is provided on the second pure water pipe 66. The on-off valve V5 starts and stops the discharge of pure water from the chemical liquid nozzle 51.

[0036] The chemical liquid pipe 59, the ozone water pipe 63, and the second pure water pipe 66 are arranged so as to pass through the inside of the arm body 53 and the rotating shaft 55, respectively.

[0037] Chemical solution nozzle 51 is provided at the tip of arm body 53. Arm body 53 is configured to extend horizontally. The base end of arm body 53 is connected to the upper part of pivot shaft 55. Rotation shaft 55 is configured to extend vertically. A nozzle pivoting mechanism 57 is provided at the lower part of pivot shaft 55.

[0038] Nozzle turning mechanism 57 includes an electric motor. When nozzle turning mechanism 57 rotates turning shaft 55 about vertical axis AX4, chemical solution nozzle 51 and arm body 53 turn about vertical axis AX4. Note that chemical solution arm 7 may include an electric motor that raises and lowers chemical solution nozzle 51.

[0039] 2, the standby position of chemical nozzle 51 is near polishing tool turning mechanism 41 and is a position in the −X direction of nozzle turning mechanism 57. When polishing tool 31 and chemical nozzle 51 are at the standby position, polishing arm 5 and chemical arm 7 are arranged in an L-shape in a plan view, as shown in FIG.

[0040] Returning to FIG. 1, the substrate processing apparatus 1 includes a control unit 71 and a storage unit (not shown). The control unit 71 controls each component of the substrate processing apparatus 1. The control unit 71 includes one or more processors, such as a central processing unit (CPU). The storage unit includes at least one of a read-only memory (ROM), a random-access memory (RAM), and a hard disk. The storage unit stores computer programs required to control each component of the substrate processing apparatus 1.

[0041] (2) Operation of the substrate processing apparatus 1 (rear surface cleaning) Next, the operation of the substrate processing apparatus 1 will be described with reference to the flowchart in Fig. 3. Fig. 4(a) to Fig. 4(f), Fig. 5, Fig. 6(a) and Fig. 6(b) are diagrams for explaining the operation of the substrate processing apparatus 1. Note that the rear surface of the substrate W refers to the surface on which no electronic circuits are formed, as opposed to the front surface of the substrate W, which is the surface on which electronic circuits are formed (device surface).

[0042] A transfer robot (not shown) transfers the substrate W with its back surface facing upward to the holding and rotating unit 2. The holding and rotating unit 2 holds the transferred substrate W. As shown in FIG. 6(a), for example, fine scratches (or pits) SRT1, deeper scratches (or pits) SRT2, and particles (metallic debris) MT are attached to the back surface of the substrate W.

[0043] After the substrate W is held, the on-off valve V1 is operated to an open state. As a result, gas is discharged from the gas discharge port 19 so that the gas flows from the center of the substrate W to the edge of the substrate W in the gap between the substrate W and the spin base 15. This makes it possible to prevent, for example, FOMs and the like from getting around to the underside (device surface) of the substrate W.

[0044] [Step S01] Start rotating the substrate The holding and rotating unit 2 rotates the substrate W in a horizontal position. The substrate W is rotated around a vertical axis AX1. The rotation of the substrate W continues between steps S01 to S10.

[0045] [Step S02] Discharge of FOM In steps S02 to S04, the substrate W is rotated at, for example, 800 rpm. The nozzle rotation mechanism 57 of the chemical arm 7 moves the chemical nozzle 51 from the standby position of the substrate W to above the center of the substrate W. Thereafter, the control unit 71 causes the chemical nozzle 51 to discharge FOM (a mixed chemical solution of hydrofluoric acid and ozone water) onto the back surface (top surface) of the substrate W being rotated (see FIGS. 4(a) and 4(b)). At this time, the on-off valve V3 is operated to an open state, and the two on-off valves V4 and V5 are operated to a closed state. The FOM that has landed on the substrate W being rotated spreads over the entire surface of the substrate W, and excess FOM is discharged outside the substrate W.

[0046] When the FOM is dispensed onto the rear surface (top surface) of the rotating substrate W, the ozone water in the FOM oxidizes the bare silicon (silicon) that constitutes the substrate W (see FIG. 6(b)). The hydrofluoric acid in the FOM etches the oxide film on the substrate W (see FIG. 6(c)). That is, the oxide film can be removed while converting it into an oxide film. Furthermore, the oxide film and nitride film that adhere to the rear surface of the substrate W before the FOM is dispensed in step S02 can be removed. Therefore, even the bare silicon that constitutes the substrate W can be etched. This makes it possible to remove fine scratches and dents that have formed on the top surface (back surface) of the substrate W (see FIG. 6(d)). Furthermore, the surface roughness of the rear surface of the substrate W can be improved.

[0047] [Step S03] Discharge of ozone water The chemical nozzle 51 remains above the center of the substrate W. After the FOM has been discharged from the chemical nozzle 51 for a preset time, the control unit 71 opens the on-off valve V4 and closes the two on-off valves V3 and V5. This causes ozone water to be discharged from the chemical nozzle 51 onto the back surface of the substrate W (see FIGS. 4(c) and 4(d)). The ozone water that has landed on the back surface of the substrate W is spread over the entire surface of the substrate W as the substrate W rotates, and excess liquid is discharged outside the substrate W. The ozone water can make the back surface of the substrate W hydrophilic, thereby preventing foreign matter from re-adhering to the surface.

[0048] [Step S04] Rinse treatment The chemical nozzle 51 remains above the center of the substrate W. After the ozone water has been discharged from the chemical nozzle 51 for a preset time, the control unit 71 opens the on-off valve V5 and closes the two on-off valves V3 and V4. This causes pure water (e.g., DIW) to be discharged from the chemical nozzle 51 onto the back surface of the substrate W. This causes the ozone water and the like on the substrate W to be washed away to the outside of the substrate W.

[0049] Thereafter, the control unit 71 controls the three on-off valves V3, V4, and V5 to close, thereby stopping the discharge of pure water from the chemical nozzle 51. Thereafter, the nozzle turning mechanism 57 moves the chemical nozzle 51 from above the center of the substrate W to a standby position for the substrate W.

[0050] [Step S05] Rinse and polishing (grinding) process After the discharge of the deionized water from the chemical nozzle 51 stops, the substrate W is rotated at, for example, 500 rpm. Thereafter, the control unit 71 controls the on-off valve V2 to an open state, thereby discharging the deionized water (for example, DIW) from the fixed nozzle 3 (see FIG. 4(f)). For convenience of illustration, the fixed nozzle 3 is shown on the right side of FIG. 4(f).

[0051] The pure water discharged from the fixed nozzle 3 is deposited near the center of the substrate W so as not to directly hit the polishing tool 31 that contacts the center of the substrate W. In addition, the polishing tool rotating mechanism 41 of the polishing arm 5 moves the polishing tool 31 from the standby position to above the center of the substrate W.

[0052] Thereafter, the control unit 71 presses the polishing tool 31 against the back surface of the rotating substrate W while discharging pure water from the fixed nozzle 3 onto the back surface of the rotating substrate W (polishing tool pressing step). That is, while pure water is being discharged from the fixed nozzle 3, the lifting mechanism 39 of the polishing arm 5 lowers the polishing tool 31 to press the polishing tool 31 against the back surface of the rotating substrate W. The polishing arm 5 has a load sensor (load cell) not shown. The pressing load of the polishing tool 31 against the substrate W is controlled to be, for example, 20 gf (gram force). When the polishing tool 31 polishes (grinds) the back surface of the substrate W, the polishing tool 31 is rotated about the vertical axis AX2 by the electric motor 37.

[0053] Furthermore, the control unit 71 moves the polishing tool 31 from the center of the substrate W to the edge of the substrate W while pressing the polishing tool 31 against the back surface of the substrate W (see FIGS. 4(e) and 4(f)). When the polishing tool 31 reaches the edge of the substrate W, the lifting mechanism 39 raises the polishing tool 31. Thereafter, when the rinsing liquid / polishing process is repeated, the polishing tool rotating mechanism 41 moves the polishing tool 31 from above the edge of the substrate W to above the center of the substrate W.

[0054] 5, one rinse / polish process is performed by pressing the polishing tool 31 against the rear surface of the rotating substrate W, moving the polishing tool 31 from the center of the substrate W to the edge of the substrate W, and then, with the polishing tool 31 released from the rear surface of the substrate W, moving the polishing tool 31 from the edge of the substrate W to the center of the substrate W. This rinse / polish process is repeated, for example, three more times. That is, a total of four rinse / polish processes are performed.

[0055] As a result, the polishing tool 31 peels off particles MT from the substrate W and polishes the back surface of the substrate W, including scratches SRT2 and the like remaining from etching with FOM (see FIG. 6(e)). The polishing process also flattens the unevenness (waviness and surface roughness) on the back surface of the substrate W. Furthermore, before the rinsing liquid / polishing process, an etching process with FOM is performed. This makes it easier to peel off particles (e.g., metal dust) that have embedded in the back surface of the substrate W. Thereafter, the polishing tool 31 actively polishes (grinds) the back surface of the substrate W. This makes it even easier to peel off particles from the back surface of the substrate W. After four rinsing liquid / polishing processes have been performed, the polishing arm 5 returns the polishing tool 31 to the standby position.

[0056] [Step S06] Rinse treatment After the four rinse and polishing processes, pure water is continuously ejected from the fixed nozzle 3 onto the rear surface of the rotating substrate W. The rotation speed of the substrate W is, for example, 500 rpm. This allows the substrate W after the rinse and polishing processes to be rinsed.

[0057] [Step S10] Spin drying Thereafter, the on-off valve V2 is operated to a closed state, and the supply of pure water from the fixed nozzle 3 is stopped. The holding and rotating unit 2 also rotates the substrate W at a high speed (for example, 1500 rpm). This performs a spin-drying process to dry the substrate W.

[0058] [Step S11] Stopping the rotation of the substrate Thereafter, the holding and rotating unit 2 stops the rotation of the substrate W. Furthermore, the control unit 71 operates the on-off valve V1 to stop the gas from being discharged from the gas discharge port 19. Thereafter, the holding and rotating unit 2 releases the hold of the substrate W. A transport robot (not shown) receives the substrate W whose back surface has been cleaned from the holding and rotating unit 2, and transports the substrate W to its next destination.

[0059] According to this embodiment, when the FOM is discharged onto the rear surface of the substrate W, the silicon is oxidized by ozone water, and the oxide film (SiO) is etched by hydrofluoric acid. This makes it possible to remove fine scratches and dents formed on the rear surface of the substrate W. Furthermore, the FOM etches the periphery of particles MT firmly attached to the rear surface of the substrate W, making the particles MT easier to peel off. Thereafter, the rear surface of the substrate W is actively polished (grinded) by the polishing tool 31. This makes it even easier to peel off the particles MT from the rear surface of the substrate W. This therefore improves the removal rate of chucking marks formed on the substrate W.

[0060] In addition, the mixed chemical solution can improve the surface roughness of the backside of the substrate, which reduces the burden of polishing to remove scratches SRT2 and other residues left by etching with the mixed chemical solution. Example 2

[0061] Next, a second embodiment of the present invention will be described with reference to the drawings. Note that descriptions that overlap with those of the first embodiment will be omitted. Fig. 7 is a flowchart showing the operation of the substrate processing apparatus 1 according to the second embodiment.

[0062] In Example 1, the rinsing liquid / polishing process and the rinsing process of steps S05 and S06 were performed, followed by spin drying of step S10. In this regard, as shown in Fig. 7, after the rinsing liquid / polishing process (including the polishing tool pressing process and the polishing tool moving process) and the rinsing process of steps S05 and S06, a process of discharging FOM (step S07) may be performed again. The operation of Example 2 is performed by the substrate processing apparatus 1 of Example 1 shown in Figs. 1 and 2.

[0063] The operation of the substrate processing apparatus 1 of the second embodiment will be described with reference to the flowchart of Fig. 7. Note that steps S01 to S06 and steps S10 and S11 of the second embodiment shown in Fig. 7 are the same as steps S01 to S06 and steps S10 and S11 of the first embodiment.

[0064] [Step S07] Discharge of second FOM Furthermore, in steps S07 to S09, the substrate W is rotated at, for example, 800 rpm. After the rinsing process in step S06, the nozzle rotation mechanism 57 of the chemical arm 7 moves the chemical nozzle 51 from the standby position of the substrate W to above the center of the substrate W. Thereafter, the control unit 71 causes the chemical nozzle 51 to discharge FOM (a mixed chemical solution of hydrofluoric acid and ozone water) onto the back surface (top surface) of the substrate W being rotated (see FIGS. 4(a) and 4(b)). At this time, the on-off valve V3 is operated to an open state, and the two on-off valves V4 and V5 are operated to a closed state. The FOM that has landed on the substrate W being rotated spreads over the entire surface of the substrate W, and excess FOM is discharged outside the substrate W.

[0065] During the rinse and polishing process in step S05, scratches may remain on the back surface of the substrate W due to the polishing tool 31. These scratches may cause defocusing in the EUV process. Therefore, in step S07, FOM is again ejected onto the back surface of the rotating substrate W to etch the polished surface (back surface). The ozone water in the FOM oxidizes the silicon on the polished surface and removes the oxide film (SiO2). This removes scratches caused by the polishing process and improves the surface roughness of the polished surface. Note that in Figure 6(b), oxide films are more likely to be generated on the back surface of the substrate W than inside scratches, which is thought to improve the surface roughness of the polished surface.

[0066] If the scratches caused by the polishing process are smaller than the scratches caused by the chucking marks, the discharge time of the FOM in step S07 may be shorter than the discharge time of the FOM in step S02.

[0067] [Steps S08, S09] Discharge of ozone water and rinsing After the second FOM discharge process (etching process) is performed, the control unit 71 discharges ozone water from the chemical nozzle 51 onto the rear surface of the rotating substrate W for a predetermined time (step S08). Thereafter, the control unit 71 discharges pure water from the chemical nozzle 51 onto the rear surface of the rotating substrate W for a predetermined time. After the rinsing process in step S09 is performed, the drying process in step S10 is performed.

[0068] According to this embodiment, after the polishing process (the polishing tool pressing process and the polishing tool moving process), the control unit 71 again discharges the FOM from the chemical solution nozzle onto the rear surface of the rotating substrate (second mixed chemical solution discharge process). The polishing process can flatten the rear surface of the substrate W while removing chucking marks on the rear surface of the substrate W, but scratches caused by the polishing tool 51 may remain. Therefore, by discharging the FOM onto the rear surface of the substrate W after the polishing process, scratches caused by the polishing tool 51 can be removed. Furthermore, because scratches caused by the polishing tool 51 can be removed by the FOM in step S02, the liquid supply configuration can be simplified.

[0069] The present invention is not limited to the above-described embodiment, but can be modified as follows.

[0070] (1) In the second FOM discharging step (step S07) of the second embodiment described above, when the FOM was being discharged from the chemical nozzle 51, the control unit 71 stopped the chemical nozzle 51 at a position above the center of the substrate W without moving the chemical nozzle 51 in the horizontal direction. Therefore, the FOM was continuously discharged above the center of the substrate W (at a fixed point). In this regard, in the second FOM discharging step, when the FOM was being discharged from the chemical nozzle 51, the control unit 71 may move the chemical nozzle 51 between above the center of the substrate W and above the edge of the substrate W.

[0071] FIG. 8 shows the film thickness of the substrate W before and after etching using FOM. In FIG. 8, the horizontal axis represents the distance from the center of the substrate W (maximum 150 mm), and the vertical axis represents the thickness of the substrate W. Note that a silicon substrate with a diameter of 300 mm was used in the etching process shown in FIG. 8. In the etching process shown in FIG. 8, FOM was continuously discharged onto the center of the rotating substrate W, and then onto the edges of the substrate W. As shown in FIG. 8, if FOM was continuously discharged at fixed points onto the center and edges of the substrate W, the film thickness of the silicon substrate at the center and edges of the substrate W was further reduced. This may result in unevenness on the back surface of the substrate W that had been planarized by the rinse and polishing process.

[0072] 9, while the FOM is being discharged from the chemical nozzle 51, the nozzle rotation mechanism 57 moves the chemical nozzle 51 between above the center of the substrate W and above the edge of the substrate W. This makes it possible to remove scratches caused by the polishing process while preventing the etching process using the FOM from causing irregularities on the back surface of the substrate W that has been flattened by the rinse liquid and polishing process.

[0073] When FOM is being ejected from the chemical nozzle 51, the chemical nozzle 51 may move back and forth between above the center of the substrate W and above the edge of the substrate W, or the chemical nozzle 51 may move only in the outward direction.

[0074] According to this modification, scratches caused by the polishing tool can be removed, but if the mixed chemical solution continues to be deposited from the chemical solution nozzle at the same position on the back surface of the substrate, there is a possibility that etching will progress too far at that position. Therefore, by moving the position of the mixed chemical solution, it is possible to prevent localized etching from progressing on the back surface of the substrate that has been flattened by the polishing process.

[0075] (2) In the FOM discharge step (step S02) in each of the above-described embodiments and modified example (1), when the FOM is being discharged from the chemical nozzle 51, the control unit 71 does not move the chemical nozzle 51 in the horizontal direction, but stops the chemical nozzle 51 at a position above the center of the substrate W. In this regard, as in modified example (1), when the FOM is being discharged from the chemical nozzle 51 in step S02 of FIG. 3 or FIG. 7, the control unit 71 may move the chemical nozzle 51 between above the center of the substrate W and above the edge of the substrate W.

[0076] (3) In each of the above-described embodiments and modifications, the rinse and polishing processes are performed a total of four times in step S05, but this is not limiting. That is, the rinse and polishing processes may be performed once or more.

[0077] (4) In each of the above-described embodiments and modifications, the control unit 71 moves the polishing tool 31 from the center of the substrate W to the edge of the substrate W while pressing the polishing tool 31 against the rear surface of the substrate W. The movement direction of the polishing tool 31 for polishing the rear surface of the substrate W is not limited to the direction from the center of the substrate W toward the edge of the substrate W (outward). If necessary, for example, the movement direction of the polishing tool 31 for polishing may be the direction from the edge of the substrate W toward the center of the substrate W (inward). Furthermore, the movement direction may be both outward and inward.

[0078] (5) In the above-described embodiments and modifications, the fixed nozzle 3 and the chemical nozzle 51 discharge pure water as a rinse liquid. However, the rinse liquid is not limited to pure water. For example, carbonated water, hydrogen water, or electrolytic ion water may also be used as the rinse liquid.

[0079] (6) In the above-described embodiments and modifications, the polishing tool rotating mechanism 41 serving as the polishing tool moving mechanism rotates the polishing tool 31 around the vertical axis AX3. However, the polishing tool moving mechanism may be configured to move the polishing tool 31 linearly in the horizontal direction. Alternatively, the polishing tool moving mechanism may be configured to move the polishing tool 31 in the X and Y directions. The same applies to the chemical nozzle 51.

[0080] (7) In the above-described embodiments and modifications, the chemical nozzle 51 selectively ejects the FOM, ozone water, and pure water. However, the ozone water and pure water may be ejected from individual nozzles.

[0081] (8) In the above-described embodiments and modifications, the resin body of the grinding tool 31 is not soft like a sponge, but is hard enough to deform slightly when pressed. In this regard, the resin body may be formed in a sponge-like shape.

[0082] (9) In the above-described embodiments and modifications, the step of discharging the ozone water in step S03 is performed after the step of discharging the FOM in step S02. However, the step of discharging the ozone water in step S03 does not have to be performed after the step of discharging the FOM in step S02. [Explanation of symbols]

[0083] 1... Substrate processing equipment 2... Rotating holding part 3... Fixed nozzle 5... Polishing arm 7... Chemical solution arm 31 … Polishing tool 39... Lifting mechanism 41 ... Grinding tool swivel mechanism 51 ... Chemical nozzle 57... Nozzle rotation mechanism 71 ... Control section

Claims

1. a substrate rotation step of rotating a substrate made of silicon in a horizontal position; a mixed chemical solution discharge step of discharging a mixed chemical solution of hydrofluoric acid and ozone water from a chemical solution nozzle onto the rear surface of the substrate being rotated; a polishing tool pressing step of pressing a polishing tool having a resin body in which abrasive grains are dispersed against the back surface of the substrate being rotated while a rinse liquid is being discharged from a rinse liquid nozzle onto the back surface of the substrate being rotated after the mixed chemical liquid discharging step; a polishing tool moving step of moving the polishing tool between the center of the substrate and an edge of the substrate while performing the polishing tool pressing step; a second mixed chemical solution discharge step of again discharging the mixed chemical solution from the chemical solution nozzle onto the rear surface of the substrate being rotated after the polishing tool pressing step and the polishing tool moving step; A substrate processing method comprising:

2. 2. The substrate processing method according to claim 1, A substrate processing method characterized in that, in the second mixed chemical solution discharge process, the chemical solution nozzle is moved between above the center of the substrate and above the edge of the substrate while the mixed chemical solution is being discharged from the chemical solution nozzle.

3. a holding and rotating unit that holds and rotates a substrate made of silicon in a horizontal position; a chemical nozzle that discharges a mixed chemical solution of hydrofluoric acid and ozone water; a rinse liquid nozzle that discharges a rinse liquid; a polishing tool having a resin body in which abrasive grains are dispersed; a grinding tool moving mechanism that moves the grinding tool; a control unit, the control unit rotates the substrate using the holding and rotating unit, the control unit discharges the mixed chemical solution from the chemical solution nozzle onto the rear surface of the substrate being rotated; After discharging the mixed chemical solution, the control unit presses the polishing tool against the rear surface of the substrate being rotated by the polishing tool moving mechanism while discharging a rinse liquid from the rinse liquid nozzle onto the rear surface of the substrate being rotated; the control unit presses the polishing tool against the rear surface of the substrate being rotated, and further moves the polishing tool between the center of the substrate and the edge of the substrate using the polishing tool moving mechanism; The control unit presses the polishing tool against the back surface of the substrate being rotated, moves it, and then ejects the mixed chemical solution from the chemical solution nozzle onto the back surface of the substrate being rotated again.

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