Substrate processing method and substrate processing apparatus

Abstract

To provide a substrate processing method and a substrate processing device, capable of causing an ultrasonic wave to act on a necessary area without damaging a pattern.SOLUTION: A substrate processing method includes: opening a pressurized valve 36 and pushing out a processing liquid from a discharge port 32 of an ultrasonic nozzle 30 to form a droplet D1 of the processing liquid; bringing the formed droplet D1 of the processing liquid into contact with a processing area P1 that is a part of an edge of a substrate W; and applying, from an ultrasonic vibrator 33, an ultrasonic wave to the droplet D1 brought into contact with the processing area P1. While ultrasonic cleaning can be performed to the processing area P1 by causing an ultrasonic wave to act on the processing area, the processing liquid does not come in contact with an area other than the processing area P1 and the ultrasonic wave does not act on the area other than the processing area P1. A pattern is formed in the area other than the processing area P1 that is a part of the edge. Accordingly, the ultrasonic wave does not act on the pattern, and acts on a necessary area while the pattern is prevented from being damaged.SELECTED DRAWING: Figure 8

Description

Technical Field

[0001] The present invention relates to a substrate processing method and a substrate processing apparatus for performing substrate processing such as cleaning or etching on a processing region of a part of a substrate. Substrates to be processed include, for example, semiconductor substrates, substrates for liquid crystal display devices, substrates for flat panel displays (FPDs), substrates for optical disks, substrates for magnetic disks, or substrates for solar cells.

Background Art

[0002] Conventionally, in the manufacturing process of semiconductor devices, a substrate processing apparatus that performs various processes on a semiconductor substrate (hereinafter simply referred to as a "substrate") has been used. As one such substrate processing apparatus, an ultrasonic cleaning apparatus that supplies a cleaning liquid to which ultrasonic waves are applied to a substrate to remove particles is known (for example, Patent Document 1).

[0003] A substrate cleaning apparatus that performs such ultrasonic cleaning (as an example, megasonic cleaning) discharges a cleaning liquid to which ultrasonic waves are applied onto the cleaning surface of the substrate, and removes contaminants such as particles adhering to the cleaning surface by cavitation generated in the cleaning liquid. Cavitation is a phenomenon in which bubbles are generated and disappear in the liquid in a short time due to a pressure change acting on the liquid. Ultrasonic cleaning removes particles and the like by a large impact generated when the bubbles disappear, and has a greater particle removal performance compared to cleaning that simply supplies a cleaning liquid.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] One of the major challenges of ultrasonic cleaning is that patterns formed on substrates are destroyed by cavitation. In other words, the impact of cavitation affects not only particles but also patterns, causing damage. As the cavitation intensity increases, particle removal performance improves, but so does the damage to the patterns. In particular, in recent years, the development of fragile patterns with large aspect ratios has progressed, and such fragile patterns are easily destroyed by ultrasonic cleaning.

[0006] Furthermore, conventional ultrasonic cleaning methods supply cleaning solution to the entire surface of the substrate, inevitably resulting in a large amount of cleaning solution being used. From the perspective of the SDGs (Sustainable Development Goals), the large amount of solution consumed is also a problem.

[0007] The present invention has been made in view of the above problems, and aims to provide a substrate processing method and a substrate processing apparatus that can apply ultrasound to the necessary areas without damaging the pattern. [Means for solving the problem]

[0008] To solve the above problems, the invention of claim 1 provides a substrate processing method for performing a predetermined substrate processing on a portion of a processing area of ​​a substrate, comprising: a holding step of holding the substrate; a droplet forming step of pushing a processing liquid from the discharge port of an ultrasonic nozzle to form droplets and bringing the droplets into contact with the processing area of ​​the substrate; and an ultrasonic application step of applying ultrasonic waves to the droplets that have come into contact with the processing area. An inert gas injection step is performed in which an inert gas is blown onto the processing area when the droplet is in contact with the substrate. The method is characterized by comprising a suction step of aspirating the liquid droplet that has come into contact with the processing area.

[0010] Furthermore, claims 2 The invention is claimed 1 In the substrate processing method according to the invention, the inert gas ejection step is characterized in that an inert gas is blown from the center of the substrate toward the outer edge.

[0011] Furthermore, claims 3 The invention is as described in claim 1 or claim 2The substrate processing method according to the invention is further characterized by comprising a nozzle cleaning step of cleaning the ultrasonic nozzle in a nozzle cleaning tank.

[0012] Furthermore, claims 4 The invention is as follows: 3 A substrate processing method according to any of the inventions, characterized in that the inner diameter of the discharge port is 0.5 mm or more and 1.0 mm or less.

[0013] Furthermore, claims 5 The present invention relates to a substrate processing apparatus for performing a predetermined substrate processing on a portion of a substrate, comprising: a substrate holding unit for holding the substrate; an ultrasonic nozzle for pushing out a processing liquid from a discharge port to form droplets and applying ultrasonic waves to the droplets; and a nozzle driving mechanism for moving the ultrasonic nozzle. An inert gas ejection unit that blows an inert gas onto the processing area when the droplet is in contact with the substrate, The device is characterized by comprising the following: bringing a droplet of processing liquid formed at the discharge port of the ultrasonic nozzle into contact with the processing area of ​​the substrate held by the substrate holding part; applying ultrasonic waves to the droplet; and then aspirating the droplet.

[0015] Furthermore, claims 6 The invention is claimed 5 In the substrate processing apparatus according to the invention, the inert gas ejection unit is characterized by blowing inert gas from the center of the substrate toward the outer edge.

[0016] Furthermore, claims 7 The invention is Claim 5 or Claim 6 The substrate processing apparatus according to the invention is further characterized by comprising a nozzle cleaning tank for cleaning the ultrasonic nozzle.

[0017] Furthermore, claims 8 The invention is claimed 5 Claims 7 A substrate processing apparatus according to any of the inventions, characterized in that the inner diameter of the discharge port is 0.5 mm or more and 1.0 mm or less. [Effects of the Invention]

[0018] Claims 1 to Claims4 According to the invention, the processing liquid is extruded from the discharge port of the ultrasonic nozzle to form droplets, the droplets are brought into contact with the processing region of the substrate, and ultrasonic waves are applied to the contacted droplets. Therefore, the processing liquid does not come into contact with areas other than the processing region, ultrasonic waves do not act thereon, and ultrasonic waves can be made to act on the necessary regions without damaging the pattern. Furthermore, since an inert gas is blown onto the processing area while the droplet is in contact with the substrate, the processing area is isolated from oxygen, preventing watermarks from forming on the processing area.

[0020] Particularly, according to the invention of claim 2 Since the inert gas is blown from the center of the substrate toward the outer peripheral end, it is possible to prevent the processing liquid from flowing toward the inner region of the substrate on which the pattern is formed.

[0021] Claim 5 to claim 8 According to the invention, the droplets of the processing liquid formed at the discharge port of the ultrasonic nozzle are brought into contact with the processing region of the substrate, and ultrasonic waves are applied to the droplets. Therefore, the processing liquid does not come into contact with areas other than the processing region, ultrasonic waves do not act thereon, and ultrasonic waves can be made to act on the necessary regions without damaging the pattern. Furthermore, since an inert gas is blown onto the processing area while the droplet is in contact with the substrate, the processing area is isolated from oxygen, preventing watermarks from forming on the processing area.

[0023] Particularly, according to the invention of claim 6 Since the inert gas is blown from the center of the substrate toward the outer peripheral end, it is possible to prevent the processing liquid from flowing toward the inner region of the substrate on which the pattern is formed.

Brief Description of the Drawings

[0024] [Figure 1] It is a plan view of a substrate processing apparatus according to the present invention. [Figure 2] It is a side view showing a main part configuration of the substrate processing apparatus. [Figure 3] It is a diagram showing a configuration of an ultrasonic nozzle. [Figure 4] It is a diagram showing a configuration of a nozzle cleaning tank. [Figure 5] It is a flowchart showing an operation procedure in the substrate processing apparatus. [Figure 6]This diagram shows the ultrasonic nozzle positioned directly above the processing area of ​​the substrate. [Figure 7] This figure shows the state in which droplets of the processing liquid are formed at the discharge port of the ultrasonic nozzle. [Figure 8] This figure shows the state in which droplets of the processing solution are in contact with the processing area of ​​the substrate. [Figure 9] This figure shows the state in which a droplet in contact with the processing area is sucked in by an ultrasonic nozzle. [Modes for carrying out the invention]

[0025] Embodiments of the present invention will be described in detail below with reference to the drawings. In the following, expressions indicating relative or absolute positional relationships (e.g., "in one direction," "along one direction," "parallel," "orthogonal," "center," "concentric," "coaxial," etc.) shall, unless otherwise specified, not only strictly represent the positional relationship but also represent a state in which there is a relative displacement in terms of angle or distance within a tolerance or a range in which a similar level of function can be obtained. Similarly, expressions indicating equality (e.g., "identical," "equal," "homogeneous," etc.) shall, unless otherwise specified, not only represent a state in which there is a quantitatively strictly equal state but also represent a state in which there is a difference in which a tolerance or a similar level of function can be obtained. Furthermore, expressions indicating shape (e.g., "circular," "square," "cylindrical," etc.) shall, unless otherwise specified, not only strictly represent the geometrically precise shape but also represent a shape within a range in which a similar level of effect can be obtained, and may have, for example, irregularities or chamfers. Additionally, expressions such as "equipped," "possessing," "containing," "having," etc., for a component are not exclusive expressions that exclude the existence of other components. Furthermore, the expression "at least one of A, B, and C" includes "A only," "B only," "C only," "any two of A, B, and C," and "all of A, B, and C."

[0026] Figure 1 is a plan view of the substrate processing apparatus 1 according to the present invention. Figure 2 is a side view showing the main components of the substrate processing apparatus 1. The substrate processing apparatus 1 is a single-wafer type substrate processing apparatus that performs ultrasonic cleaning or etching on a single substrate W. The substrate W to be processed is a silicon disc-shaped semiconductor substrate. In Figure 1 and subsequent figures, the dimensions and number of parts are exaggerated or simplified as needed for ease of understanding.

[0027] The substrate processing apparatus 1 mainly comprises a processing chamber 10, a rotating holding unit 20, an ultrasonic nozzle 30, a nozzle cleaning tank 50, and a control unit 90.

[0028] The processing chamber 10 is a hollow housing. The rotating holding unit 20 and the ultrasonic nozzle 30, etc., are provided inside the processing chamber 10. During substrate processing, the processing chamber 10 houses the substrate W to be processed.

[0029] A fan filter unit (FFU) 12 is installed on the ceiling of the processing chamber 10. The fan filter unit 12 is equipped with a fan for blowing air and a filter (for example, a HEPA filter), and supplies clean air downwards from the ceiling of the processing chamber 10. In other words, the fan filter unit 12 supplies clean air to the inside of the processing chamber 10.

[0030] An exhaust pipe 18 is connected to the bottom of the processing chamber 10. The exhaust pipe 18 is connected to an exhaust mechanism (e.g., an exhaust pump) not shown. Air supplied from the fan filter unit 12 is discharged through the exhaust pipe 18, creating a downflow of clean air inside the processing chamber 10.

[0031] Furthermore, the processing chamber 10 is provided with an outlet / outlet (not shown). This outlet / outlet is opened and closed by a shutter. When the outlet / outlet is open, substrates W are loaded into and unloaded from the processing chamber 10. The outlet / outlet is closed while the substrates W are being processed.

[0032] The rotating holding unit 20 includes a spin chuck 22 and a spin motor 25. The spin chuck 22 is a substrate holding unit that holds the substrate W in a horizontal position (a position in which the normal to the main surface of the substrate W is aligned with the vertical direction). In this embodiment, the spin chuck 22 is a vacuum suction type chuck. The spin chuck 22 holds the central part of the lower surface of the substrate W by suction. Note that the spin chuck may be other types of chucks, such as a clamping type mechanical chuck.

[0033] The spin chuck 22 has a disc shape with a diameter smaller than the diameter of the substrate W. When the lower surface of the substrate W is held by the spin chuck 22, the peripheral edge of the substrate W protrudes outward beyond the outer edge of the spin chuck 22.

[0034] The spin chuck 22 is connected to the spin motor 25 via the spin shaft 27. That is, the upper end of the spin shaft 27 of the spin motor 25 is connected to the center of the lower surface of the spin chuck 22. When the spin motor 25 rotates the spin shaft 27 while the substrate W is held in contact with the spin chuck 22, the substrate W and the spin chuck 22 rotate in the horizontal plane around the rotation axis A1 which is aligned vertically.

[0035] A cup 40 is provided to surround the spin chuck 22. The cup 40 has a cylindrical shape, and the upper part of the cup 40 is sloped so that it approaches the spin chuck 22 as it goes upwards. However, the inner diameter of the upper part of the cup 40 is larger than the diameter of the substrate W. The upper end of the cup 40 is higher than the height of the substrate W held by the spin chuck 22. Therefore, liquid scattered by centrifugal force from the substrate W rotated by the spin motor 25 is caught and collected by the cup 40. The liquid collected by the cup 40 is discharged from a drain pipe provided at the bottom of the cup 40. The cup 40 may also have a multi-stage structure with multiple collection ports for different purposes.

[0036] The ultrasonic nozzle 30 is attached to the tip of a horizontally extending rod-shaped nozzle arm 61. The nozzle arm 61 is supported by an arm support shaft 62 that extends vertically. The arm support shaft 62 is connected to a nozzle drive unit 63. The nozzle drive unit 63 rotates the arm support shaft 62 around a rotation axis A2 along the vertical direction. When the nozzle drive unit 63 rotates the arm support shaft 62, the nozzle arm 61 performs a pivoting motion, and as shown by arrow AR1 in Figure 1, the ultrasonic nozzle 30 moves along an arc trajectory between a standby position outside the cup 40 and a processing position above the substrate W held by the spin chuck 22.

[0037] Furthermore, the nozzle drive unit 63 moves the arm support shaft 62 and the nozzle arm 61 up and down. As a result, the ultrasonic nozzle 30 also moves up and down along the vertical direction.

[0038] Figure 3 shows the configuration of the ultrasonic nozzle 30. The main body 31 of the ultrasonic nozzle 30 is composed of a hollow cylindrical upper body 31a and a circular tube-shaped lower body 31b. The inner diameter of the upper body 31a is larger than the inner diameter of the lower body 31b. The connection portion between the upper body 31a and the lower body 31b is tapered.

[0039] The lower end of the main body's lower section 31b is an open end, which serves as the discharge port 32 of the ultrasonic nozzle 30. The inner diameter d of the discharge port 32 is between 0.5 mm and 1.0 mm.

[0040] An ultrasonic transducer 33 is provided in the upper part of the inner space of the upper part 31a of the main body. High-frequency power is supplied to the ultrasonic transducer 33 from a high-frequency power supply (not shown). When high-frequency power is supplied, the ultrasonic transducer 33 generates ultrasonic waves.

[0041] Furthermore, a pressure pipe 34 and a suction pipe 35 are connected in communication to the upper part 31a of the main body 31. The tip of the pressure pipe 34 is connected to the upper part 31a of the main body, and its base end is connected to the processing liquid supply mechanism 71. A pressure valve 36 is provided along the path of the pressure pipe 34.

[0042] The processing liquid supply mechanism 71 includes a tank for storing the processing liquid and a pump, etc. The processing liquid supply mechanism 71 supplies the processing liquid to the pressurizing pipe 34 at a predetermined pressure. In this specification, "processing liquid" is a conceptual term that includes various chemicals and pure water. Examples of chemicals include solutions for etching or solutions for removing particles, and specifically, SC-1 solution (a mixed solution of ammonium hydroxide, hydrogen peroxide, and pure water), SC-2 solution (a mixed solution of hydrochloric acid, hydrogen peroxide, and pure water), or hydrofluoric acid (HF) are used. Chemicals also include those diluted with pure water. In this embodiment, the processing liquid supply mechanism 71 supplies pure water to the main body 31 as the processing liquid.

[0043] The pressure valve 36 opens and closes the flow path of the pressure pipe 34. While the processing liquid is supplied from the processing liquid supply mechanism 71 to the pressure pipe 34, when the pressure valve 36 opens the flow path of the pressure pipe 34, the processing liquid is supplied into the main body 31 at a predetermined pressure (positive pressure). When the pressure valve 36 closes the flow path of the pressure pipe 34, the supply of processing liquid to the main body 31 is stopped. Note that the opening or closing of the flow path of the pressure pipe 34 by the pressure valve 36 is also referred to as the pressure valve 36 being opened or closed.

[0044] Meanwhile, the tip of the suction tube 35 is connected to the upper part 31a of the main body, and the base end is connected to the suction mechanism 72. A suction valve 37 is provided along the path of the suction tube 35.

[0045] The suction mechanism 72 is equipped with a pump for drawing in liquid. The suction mechanism 72 draws the processing liquid from the suction pipe 35 at a predetermined pressure.

[0046] The suction valve 37 opens and closes the flow path of the suction tube 35. As the suction mechanism 72 draws liquid from the suction tube 35, when the suction valve 37 opens the flow path of the suction tube 35, the processing liquid is drawn from the main body 31 at a predetermined pressure (negative pressure). When the suction valve 37 closes the flow path of the suction tube 35, the suction of the processing liquid from the main body 31 stops. Note that the opening or closing of the flow path of the suction tube 35 by the suction valve 37 is also referred to as the suction valve 37 being opened or closed.

[0047] Furthermore, as shown in Figures 1 and 2, a support member 81 is attached to the nozzle arm 61, and the inert gas nozzle 82 is supported by this support member 81. Since both the ultrasonic nozzle 30 and the inert gas nozzle 82 are attached to the same nozzle arm 61, they both perform the same movement while maintaining a constant relative position. For example, when the ultrasonic nozzle 30 moves along an arc trajectory as indicated by arrow AR1 in Figure 1, the inert gas nozzle 82 also moves along the same arc trajectory.

[0048] As shown in Figure 3, the inert gas nozzle 82 is connected to the inert gas supply source 83 via piping 85. A valve 84 is provided in piping 85. When the valve 84 is opened, inert gas (nitrogen (N2) in this embodiment) is supplied from the inert gas supply source 83 to the inert gas nozzle 82, and the inert gas nozzle 82 ejects the inert gas. The inert gas nozzle 82 blows the inert gas directly below the discharge port 32, which includes the discharge port 32 of the ultrasonic nozzle 30. The inert gas ejected by the inert gas nozzle 82 may be helium (He) or argon (Ar).

[0049] The control unit 90 controls various operating mechanisms provided in the substrate processing apparatus 1. The hardware configuration of the control unit 90 is similar to that of a general computer. Specifically, the control unit 90 includes a CPU, which is a circuit that performs various calculations; a ROM, which is a read-only memory that stores basic programs; a RAM, which is a read-write memory that stores various information; and a storage unit (for example, a magnetic disk or SSD) that stores control software and data. The control unit 90 is electrically connected to the pressure valve 36 and the suction valve 37, etc., and controls their operation.

[0050] The nozzle cleaning tank 50 is located outside the cup 40, near the standby position of the ultrasonic nozzle 30. Figure 4 shows the configuration of the nozzle cleaning tank 50. The nozzle cleaning tank 50 stores cleaning fluid. This cleaning fluid may be the same as the processing fluid used by the ultrasonic nozzle 30. When cleaning the ultrasonic nozzle 30, the area near the discharge port 32 at the lower part 31b of the main body is immersed in the cleaning fluid.

[0051] The nozzle cleaning tank 50 is equipped with a drying nozzle 55. The drying nozzle 55 blows air supplied from an air supply source (not shown) onto the ultrasonic nozzle 30, which is being drawn out of the nozzle cleaning tank 50. This dries the outer surface of the ultrasonic nozzle 30.

[0052] Next, the operation of the substrate processing apparatus 1 will be described. Figure 5 is a flowchart showing the operation procedure of the substrate processing apparatus 1. First, before processing of the substrate W begins, the ultrasonic nozzle 30 is cleaned (step S1). When the substrate W is not present in the processing chamber 10, the ultrasonic nozzle 30 is in standby position outside the cup 40. A nozzle cleaning tank 50 is provided in this standby position. When the ultrasonic nozzle 30 is in standby position, the ultrasonic nozzle 30 is cleaned in the nozzle cleaning tank 50. The state in which the ultrasonic nozzle 30 is being cleaned in standby position is defined as the standby state of the ultrasonic nozzle 30.

[0053] Specifically, as shown in Figure 4, the lower end portion of the lower part 31b of the main body of the ultrasonic nozzle 30 is immersed in the cleaning fluid stored in the nozzle cleaning tank 50, and the outer wall surface near the discharge port 32 is cleaned. In addition, the pressure valve 36 is opened and cleaning fluid (pure water in this embodiment) is supplied to the inside of the main body 31 of the ultrasonic nozzle 30. When cleaning the ultrasonic nozzle 30, the pressure valve 36 is kept open and cleaning fluid is continuously supplied into the main body 31. The cleaning fluid supplied to the main body 31 is discharged from the discharge port 32 into the cleaning fluid stored in the nozzle cleaning tank 50. Therefore, during cleaning of the ultrasonic nozzle 30, the inside of the main body 31 of the ultrasonic nozzle 30 is filled with cleaning fluid, and this cleaning fluid flows toward the discharge port 32. Ultrasound is then applied from the ultrasonic transducer 33 to the cleaning fluid filling the main body 31. As a result, the inner wall surface of the main body 31 of the ultrasonic nozzle 30 is ultrasonically cleaned. Contaminants detached from the inner wall surface of the main body 31 by ultrasonic cleaning are discharged together with the cleaning solution from the discharge port 32 at the lower end of the main body 31 into the nozzle cleaning tank 50. In this way, both the inner and outer wall surfaces of the main body 31 of the ultrasonic nozzle 30 are cleaned.

[0054] Next, when processing of the substrate W is to begin, an external transport robot carries the substrate W to be processed into the processing chamber 10 and holds it in the spin chuck 22 (step S2). The spin chuck 22 holds the substrate W in a horizontal position by suction on the center of the lower surface of the transported substrate W.

[0055] After the substrate W is held in the spin chuck 22, the ultrasonic nozzle 30 moves to a predetermined processing position (step S3). When the standby ultrasonic nozzle 30 starts to move, the nozzle drive unit 63 raises the ultrasonic nozzle 30 and pulls it upward from the nozzle cleaning tank 50. While raising the ultrasonic nozzle 30, drying air is blown from the drying nozzle 55 onto the outer wall surface of the main body 31 of the ultrasonic nozzle 30 (see Figure 4). This dries the outer wall surface of the ultrasonic nozzle 30, preventing liquid from dripping onto the substrate W from the outer wall surface of the ultrasonic nozzle 30 during processing. Also, when the ultrasonic nozzle 30 starts to move, the pressure valve 36 is closed and the supply of cleaning liquid to the ultrasonic nozzle 30 is stopped. Since the suction valve 37 remains closed, the main body 31 of the ultrasonic nozzle 30 is filled with pure water, but pure water is not discharged from the discharge port 32. Furthermore, the ultrasonic transducer 33 also stops operating.

[0056] In this embodiment, a cleaning process is performed to remove particles adhering to the outer edge of the substrate W (bevel cleaning). In step S3, the control unit 90 controls the spin motor 25 to rotate the substrate W, moving the processing area (part of the edge) to be cleaned to a position where the arc trajectory of the ultrasonic nozzle 30 intersects with the outer circle of the substrate W (see Figure 1). The control unit 90 also controls the nozzle drive unit 63 to rotate the ultrasonic nozzle 30, moving it above the outer edge of the substrate W. As a result, as shown in Figure 6, the discharge port 32 of the ultrasonic nozzle 30 is positioned directly above the processing area P1 of the substrate W. In this state, both the pressure valve 36 and the suction valve 37 are stopped, and the main body 31 of the ultrasonic nozzle 30 is quietly filled with processing liquid (pure water), and the application of ultrasound from the ultrasonic transducer 33 to the processing liquid is also stopped. Furthermore, the rotation of the substrate W and the movement of the ultrasonic nozzle 30 are stopped, maintaining the state in which the ultrasonic nozzle 30 is positioned directly above the processing area P1.

[0057] Next, the processing liquid is pushed out from the discharge port 32 of the ultrasonic nozzle 30 to form droplets of the processing liquid (step S4). At this time, under the control of the control unit 90, the suction valve 37 is kept closed while the pressure valve 36 is opened for a certain period of time. When the pressure valve 36 is opened with the suction valve 37 closed, the processing liquid is supplied from the pressure pipe 34 at a predetermined pressure, pressurizing the processing liquid in the main body 31, and the processing liquid is pushed out from the discharge port 32. If the pressure valve 36 is kept open, the processing liquid will be discharged (flowed out) from the discharge port 32. However, when the pressure valve 36 is opened for a certain period of time and then closed, a certain amount of processing liquid is pushed out from the discharge port 32, and the pushed-out processing liquid forms droplets due to surface tension.

[0058] Figure 7 shows the state in which a droplet of processing liquid is formed at the discharge port 32 of the ultrasonic nozzle 30. A certain amount of processing liquid is pushed out from the discharge port 32 of the ultrasonic nozzle 30, and a droplet D1 of processing liquid is formed directly above the processing area P1 of the substrate W. The droplet D1 maintains its shape without falling from the discharge port 32 onto the substrate W due to the balance between the surface tension of the processing liquid and gravity. The surface tension of the processing liquid is determined by the surface condition of the ultrasonic nozzle 30, the viscosity of the processing liquid, the temperature of the processing liquid, etc. In other words, the opening time of the pressure valve 36 should be controlled so that an amount of processing liquid is pushed out from the discharge port 32 that does not cause the droplet D1 to fall.

[0059] After a droplet D1 of the processing liquid is formed at the discharge port 32 of the ultrasonic nozzle 30, the droplet D1 is brought into contact with the substrate W (step S5). Specifically, the nozzle drive unit 63 slowly lowers the ultrasonic nozzle 30, gently bringing the droplet D1 of the processing liquid formed at the discharge port 32 into contact with the processing area P1 of the substrate W.

[0060] Figure 8 shows the state in which a droplet D1 of the processing liquid is in contact with the processing area P1 of the substrate W. When the droplet D1 of the processing liquid, which was formed at the discharge port 32 of the ultrasonic nozzle 30, comes into contact with the processing area P1 of the substrate W, a column of processing liquid is formed between the discharge port 32 and the substrate W. At this time, the amount of liquid in the droplet D1 is not very large, so the processing liquid does not spread to the surface of the substrate W. The processing area P1 is a part of the edge of the substrate W, and the width of the edge is 1 mm to several mm, but since the inner diameter d of the discharge port 32 of the ultrasonic nozzle 30 is 0.5 mm or more and 1.0 mm or less, the droplet D1 does not extend beyond the processing area P1.

[0061] Furthermore, almost simultaneously with the contact of a droplet D1 of the processing liquid with the processing area P1 of the substrate W, the ultrasonic transducer 33 starts operating and generates ultrasonic waves. The ultrasonic waves generated from the ultrasonic transducer 33 propagate through the processing liquid filling the main body 31 and are applied to the droplet D1 in contact with the processing area P1 (step S6).

[0062] Ultrasonic cleaning of the processing area P1 is performed by applying ultrasound to droplets D1 of the processing liquid. Specifically, cavitation is generated in droplet D1 when ultrasound is applied to it. As previously described, cavitation is a phenomenon in which bubbles are generated and disappear in a liquid in a short period of time due to pressure changes acting on the liquid. Then, the large impact generated when these bubbles disappear causes contaminants such as particles attached to the processing area P1 to be detached. In this way, ultrasonic cleaning of the processing area P1 of the substrate W proceeds.

[0063] Furthermore, when the ultrasonic nozzle 30 performs ultrasonic cleaning, nitrogen gas is blown from the inert gas nozzle 82 to the vicinity of the processing area P1 in contact with the droplet D1 (step S7). When the droplet D1 is in contact with the substrate W, by blowing nitrogen gas from the inert gas nozzle 82 to the processing area P1 in contact with the droplet D1, the area around the processing area P1 becomes a nitrogen atmosphere and is isolated from oxygen, thereby preventing watermarks from forming on the processing area P1. Watermarks are stains that occur on the surface of the substrate W due to the interaction of moisture and oxygen. By blowing nitrogen gas from the inert gas nozzle 82 and blocking oxygen from the area around the processing area P1, oxidation in the processing area P1 is prevented, thus preventing the formation of watermarks.

[0064] As described above, the amount of liquid in the droplet D1 of the processing liquid formed in step S4 is not very large, so basically, when the droplet D1 comes into contact with the processing area P1, the processing liquid does not spread to the surface of the substrate W. However, depending on the wettability (contact angle) of the surface of the substrate W, there is a risk that the processing liquid may spread to the surface of the substrate W when the droplet D1 comes into contact with the processing area P1. Specifically, if the surface of the substrate W is hydrophilic (small contact angle), the processing liquid is more likely to spread to the surface of the substrate W. For this reason, it is preferable that the surface of the substrate W is hydrophobic (large contact angle).

[0065] In this embodiment, an inert gas nozzle 82 is provided inside the ultrasonic nozzle 30 as viewed from the spin chuck 22, and the inert gas nozzle 82 blows nitrogen gas from the center of the substrate W toward the outer edge. Therefore, even if the surface of the substrate W is hydrophilic and the processing liquid constituting the droplet D1 spreads across the surface of the substrate W, the processing liquid can be directed toward the outer edge of the substrate W. As a result, the processing liquid is prevented from spreading to the inner region of the substrate W where the pattern is formed (the region inside the edge) and contaminating that inner region.

[0066] After a predetermined time has elapsed since ultrasonic cleaning began with the droplet D1 in contact with the processing area P1, the ultrasonic nozzle 30 sucks up the droplet D1 that was in contact with the processing area P1 (step S8). Figure 9 shows the state in which the ultrasonic nozzle 30 has sucked up the droplet D1 that was in contact with the processing area P1. At this time, under the control of the control unit 90, the suction valve 37 is opened while the pressure valve 36 remains closed. When the suction valve 37 is opened with the pressure valve 36 closed, the processing liquid in the main body 31 is sucked into the suction tube 35, and the processing liquid at the discharge port 32 is also sucked up, creating negative pressure on the droplet D1. As a result, the droplet D1 of the processing liquid that was in contact with the processing area P1 separates from the processing area P1 and is sucked into the main body 31 via the discharge port 32. At this time, particles that have been detached from the processing area P1 by ultrasonic cleaning are also sucked into the main body 31 via the discharge port 32 along with the droplet D1. In other words, particles are removed from the processing area P1 of the substrate W. Furthermore, since the inside of the ultrasonic nozzle 30 will be cleaned later in the nozzle cleaning tank 50, it is not necessary to completely suction all of the processing liquid in the main body 31 through the suction tube 35. It is sufficient to open the suction valve 37 for a time long enough to draw the droplets D1 into the lower part 31b of the main body.

[0067] After the droplet D1 is attracted to the ultrasonic nozzle 30, the ultrasonic nozzle 30 moves back to the standby position (step S9). That is, the control unit 90 controls the nozzle drive unit 63 to rotate the ultrasonic nozzle 30 and move it to the standby position.

[0068] The ultrasonic nozzle 30, which has returned to the standby position, is subjected to the same cleaning process as in step S1. At this time, the particles that were aspirated together with the droplet D1 in step S8 are released into the nozzle cleaning tank 50 from the discharge port 32 of the ultrasonic nozzle 30.

[0069] In this embodiment, the processing liquid is pushed out from the discharge port 32 of the ultrasonic nozzle 30 to form droplets D1 of the processing liquid, and these droplets D1 are brought into contact with the processing area P1 of the substrate W, and ultrasonic waves are applied to the contacting droplets D1. As a result, ultrasonic cleaning can be performed on the processing area P1 by applying ultrasonic waves, and particles adhering to the processing area P1 can be removed. On the other hand, the processing liquid does not come into contact with areas other than the processing area P1 (including the inner area of ​​the substrate W where the pattern is formed), and ultrasonic waves do not act on these areas. Therefore, ultrasonic waves do not act on the pattern, and damage to the pattern due to cavitation caused by ultrasonic waves can be prevented. As a result, ultrasonic waves can be applied only to the areas that need cleaning, and appropriate ultrasonic cleaning can be performed on these areas, while damage to the pattern can be prevented by not applying ultrasonic waves to the areas where the pattern is formed. In other words, ultrasonic waves can be applied to the necessary areas without damaging the pattern. Note that since the processing area P1 is part of the edge of the substrate W, no pattern is formed in the processing area P1. It is preferable to set the processing area P1 as a location where contamination is likely to occur due to some component coming into contact with the edge of the substrate W in the previous process.

[0070] Furthermore, in this embodiment, the liquid droplets D1 of the processing solution are brought into contact only with the processing area P1, which is a part of the edge of the substrate W, and the processing solution is not supplied to other areas. In other words, the cleaning in this embodiment can be considered a pseudo-dry cleaning in which most of the area on the substrate W does not come into contact with the processing solution. For this reason, it is possible to significantly reduce the amount of processing solution consumed compared to conventional ultrasonic cleaning.

[0071] Furthermore, in this embodiment, when the liquid droplet D1 of the processing solution is in contact with the substrate W, nitrogen gas is blown from the inert gas nozzle 82 near the processing area P1. This isolates the processing area P1 from oxygen and prevents watermarks from forming on the processing area P1.

[0072] In particular, the inert gas nozzle 82 blows nitrogen gas from the center of the substrate W toward the outer edge. This prevents the processing liquid from flowing from the droplet D1 in contact with the processing area P1 of the substrate W toward the inner area of ​​the substrate W where the pattern is formed.

[0073] Furthermore, in this embodiment, the inner diameter d of the discharge port 32 of the ultrasonic nozzle 30 is 0.5 mm or more and 1.0 mm or less. The width of the edge of the substrate W is 1 mm to several mm. Therefore, the droplets can be brought into contact only with the edge without contacting the inner region of the substrate W, and the edge can be cleaned effectively without damaging the pattern.

[0074] While embodiments of the present invention have been described above, various modifications can be made to this invention without departing from its spirit. For example, in the above embodiments, cleaning was performed on the processing area P1, which is a part of the edge, while the substrate W was held in a stationary state. Instead, ultrasonic cleaning of the entire edge may be performed while the substrate W is rotated by the spin motor 25.

[0075] Furthermore, in the above embodiment, the cleaning process was performed on a processing area P1 which is a part of the edge of the substrate W, but the method is not limited to this, and the cleaning process may be performed on a part of the inner region. Even in the inner region of the substrate W, patterns are not formed over the entire area, and there are parts in the inner region where no patterns are formed. In such cases, a droplet D1 of the processing liquid may be brought into contact with a part of the inner region where no patterns exist, and ultrasonic waves may be applied to the droplet D1 to clean the part. Even in this way, as in the above embodiment, ultrasonic waves can be applied to the necessary area without damaging the pattern. In other words, the technology according to the present invention is a localized processing technology that processes not only the edge of the substrate W, but also any arbitrary part within the plane of the substrate W.

[0076] Furthermore, although pure water was used as the processing solution in the above embodiment, a cleaning solution such as SC-1 solution may be used instead. By performing ultrasonic cleaning using a cleaning solution such as SC-1 solution, particles firmly attached to the substrate W can be removed more effectively.

[0077] Furthermore, the substrate processing technology according to the present invention is not limited to cleaning, but may also be an etching process. Specifically, an etching solution such as hydrofluoric acid may be used as the processing solution, and an etching process may be performed on a portion of the substrate W by bringing droplets of the etching solution into contact with that portion of the substrate W. A predetermined thin film is formed on the surface of the substrate W. An etching process is performed on the thin film in that portion of the substrate W by bringing droplets of the etching solution into contact with a portion of the substrate W on which the thin film has been formed, and by applying ultrasound to the droplets. In this way, the etching solution is heated by the ultrasound, so the etching rate can be improved. In addition, the thin film can be effectively etched by the action of cavitation.

[0078] Furthermore, the substrate processing apparatus 1 may be provided with a cleaning nozzle for discharging a cleaning solution, and the cleaning solution may be discharged from the cleaning nozzle onto the surface of the substrate W before or after the ultrasonic cleaning in the above embodiment to perform the cleaning process. In particular, it is effective to discharge the cleaning solution onto the surface of the substrate W to perform the cleaning process after removing particles that have firmly adhered to the edges of the substrate W using the ultrasonic cleaning in the above embodiment.

[0079] Furthermore, in the above embodiment, both the pressurizing tube 34 and the suction tube 35 were connected to the main body 31 of the ultrasonic nozzle 30. Alternatively, a suction section may be provided on the side of the main body 31 to draw in droplets through a dedicated suction path separate from the discharge port 32. In this way, contaminants such as particles will not be drawn into the main body 31, thus more reliably preventing contamination inside the main body 31. [Explanation of Symbols]

[0080] 1. Substrate processing apparatus 10 Processing Chambers 20 Rotating holding part 22 Spin Chuck 25 Spin Motors 30 ultrasonic nozzles 31 Main body 32 Discharge port 33. Ultrasonic transducer 34 Pressurized tube 35 Suction tube 36. Pressure valve 37 Suction valve 40 cups 50 Nozzle Cleaning Tanks 55 Drying nozzle 63 Nozzle drive unit 82 Inert gas nozzle 90 Control Unit W board

Claims

1. A substrate processing method for performing a predetermined substrate processing on a portion of the processing area of ​​a substrate, A holding process for holding the substrate, A droplet formation step involves pushing a processing liquid out from the discharge port of an ultrasonic nozzle to form droplets, and bringing the droplets into contact with the processing area of ​​the substrate. An ultrasonic application step of applying ultrasonic waves to the droplet that has come into contact with the processing area, An inert gas injection step is performed in which an inert gas is blown onto the processing area when the droplet is in contact with the substrate. A suction step of aspirating the droplet that has come into contact with the processing area, A substrate processing method characterized by comprising the following:

2. In the substrate processing method according to claim 1, A substrate processing method characterized in that, in the inert gas ejection step, an inert gas is blown from the center of the substrate toward the outer edge.

3. In the substrate processing method according to claim 1, A substrate processing method characterized by further comprising a nozzle cleaning step of cleaning the ultrasonic nozzle in a nozzle cleaning tank.

4. In the substrate processing method according to any one of claims 1 to 3, A substrate processing method characterized in that the inner diameter of the discharge port is 0.5 mm or more and 1.0 mm or less.

5. A substrate processing apparatus that performs a predetermined substrate processing on a portion of the processing area of ​​a substrate, A substrate holding section that holds the substrate, An ultrasonic nozzle that pushes out a processing liquid from a discharge port to form droplets and applies ultrasonic waves to the droplets, A nozzle driving mechanism for moving the ultrasonic nozzle, An inert gas ejection unit that blows an inert gas onto the processing area when the droplet is in contact with the substrate, Equipped with, A substrate processing apparatus characterized by bringing a droplet of processing liquid formed at the discharge port of the ultrasonic nozzle into contact with the processing area of ​​the substrate held by the substrate holding part, applying ultrasonic waves to the droplet, and then aspirating the droplet.

6. In the substrate processing apparatus according to claim 5, The substrate processing apparatus is characterized in that the inert gas ejection unit blows inert gas from the center of the substrate toward the outer edge.

7. In the substrate processing apparatus according to claim 5, A substrate processing apparatus further comprising a nozzle cleaning tank for cleaning the ultrasonic nozzle.

8. In the substrate processing apparatus according to any one of claims 5 to 7, A substrate processing apparatus characterized in that the inner diameter of the discharge port is 0.5 mm or more and 1.0 mm or less.

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