Substrate processing method and substrate processing device

Abstract

To provide a substrate processing method and a substrate processing device that can form a coating film with uniform width.SOLUTION: A pretreatment liquid is supplied to an upper surface of a peripheral part of a substrate W after pattern formation, so that a liquid film 70 of the pretreatment liquid is formed. A coating liquid is then supplied onto the liquid film 70, thereby forming a coating film 80. The pretreatment liquid is a liquid containing solvent of the coating liquid, or a liquid to reduce the contact angle of the coating liquid to the upper surface of the substrate. When the liquid film 70 of the pretreatment liquid is formed, the pretreatment liquid is deposited a plurality of times in the overlapping manner on the upper surface of the peripheral part of the substrate W while rotating the substrate W at a relatively high rotation number, so that the liquid film 70 of the pretreatment liquid with the uniform width is formed. The affinity of the liquid film 70 of the pretreatment liquid and the coating liquid is extremely high. By supplying the coating liquid onto the liquid film 70 of the pretreatment liquid with the uniform width, the coating liquid spreads to the same region as the liquid film 70 and the coating film 80 with the uniform width can be formed.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a substrate processing method and a substrate processing apparatus for forming a coating film on the peripheral portion of a disk-shaped substrate, for example, a semiconductor wafer, a substrate for a liquid crystal display device, a substrate for a flat panel display (FPD), a substrate for an optical disk, a substrate for a magnetic disk, or a substrate for a solar cell. [Background technology]

[0002] In photolithography, an important technique for forming patterns in the manufacturing process of semiconductor devices, a resist film is formed on a substrate such as a semiconductor wafer, and the resist film is exposed to a pattern and then developed. If a transfer arm or a positioning unit comes into contact with the edge of a substrate on which a resist film has been formed over the entire surface in each process, the resist film may be damaged and generate dust, which may contaminate the transfer arm. For this reason, a solvent is supplied to the peripheral portion of the substrate to remove the resist film from the peripheral portion. As a result, the silicon base material is exposed at the peripheral portion of the substrate.

[0003] When a DRIE (Deep Reactive Ion Etching) process is performed using a resist film on which a pattern has been formed, damage occurs to the peripheral portion of the substrate where the base material is exposed. This causes a decrease in strength of the peripheral portion of the substrate, and may also generate particles. For this reason, Patent Documents 1 and 2 disclose a technique for forming a protective film to prevent the peripheral portion of the substrate from being etched. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 7-130703 [Patent Document 2] JP 2002-334879 A Summary of the Invention [Problem to be solved by the invention]

[0005] To form a protective film on the peripheral portion of a substrate, a coating liquid is typically supplied from a nozzle onto the upper surface of the peripheral portion, and then dried to form a coating film. It is desirable that the width of the coating film is uniform over the entire circumference of the peripheral portion of the substrate. However, the uniformity of the width of the coating film may decrease due to various factors such as vibration of the nozzle when the coating liquid is supplied, fluctuations in the discharge state of the coating liquid, or eccentricity of the substrate itself.

[0006] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a substrate processing method and a substrate processing apparatus capable of forming a coating film with a uniform width. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems, a first aspect of the present invention provides a substrate processing method for forming a coating film on a peripheral portion of a disk-shaped substrate, the method comprising: a pretreatment liquid film formation step of supplying a pretreatment liquid containing a solvent of a coating liquid for forming the coating film onto the substrate while rotating the substrate in a horizontal plane, and forming a liquid film of the pretreatment liquid in a circular coating area on an upper surface of the peripheral portion of the substrate, the width of the area being the same as a target width for forming the coating film; and a coating film formation step of supplying the coating liquid onto the liquid film of the pretreatment liquid while rotating the substrate in a horizontal plane, to form the coating film.

[0008] In addition, a second aspect is a substrate processing method for forming a coating film on a peripheral portion of a disk-shaped substrate, the method comprising: a pre-treatment liquid film formation step of supplying a pre-treatment liquid for reducing a contact angle of a coating liquid for forming the coating film on the upper surface of the substrate while rotating the substrate in a horizontal plane, and forming a liquid film of the pre-treatment liquid in a circular coating area having the same width as a target width for forming the coating film on the upper surface of the peripheral portion of the substrate; and a coating film formation step of supplying the coating liquid on top of the liquid film of the pre-treatment liquid while rotating the substrate in a horizontal plane, to form the coating film.

[0009] In a third aspect, in the substrate processing method according to the first or second aspect, in the pre-processing liquid film forming process, the pre-processing liquid is supplied to an underside of a peripheral portion of the substrate, and the pre-processing liquid is caused to flow from the edge of the substrate to an upper surface of the peripheral portion.

[0010] In a fourth aspect, in the substrate processing method according to the first or second aspect, in the pre-treatment liquid film forming step, the substrate is rotated at 500 rpm or more while the pre-treatment liquid is supplied to an upper surface of a peripheral portion of the substrate, and the pre-treatment liquid is applied to the coating area in multiple overlapping layers.

[0011] A fifth aspect is the substrate processing method according to the first or second aspect, wherein the pretreatment liquid is a liquid containing propylene glycol monomethyl ether acetate or propylene glycol monomethyl ether.

[0012] In addition, a sixth aspect is a substrate processing apparatus for forming a coating film on a peripheral portion of a disk-shaped substrate, the apparatus comprising: a rotary holding unit for rotating the substrate around a central axis of the substrate while holding the substrate in a horizontal position; a pretreatment liquid discharge nozzle for supplying a pretreatment liquid containing a solvent of a coating liquid for forming the coating film onto the rotating substrate and forming a liquid film of the pretreatment liquid in a circular coating area on an upper surface of the peripheral portion of the substrate, the width of the area being the same as a target width for forming the coating film; and a coating liquid discharge nozzle for supplying the coating liquid onto the liquid film of the pretreatment liquid formed on the upper surface of the peripheral portion of the rotating substrate, to form the coating film.

[0013] In addition, a seventh aspect is a substrate processing apparatus for forming a coating film on a peripheral portion of a disk-shaped substrate, the apparatus comprising: a rotating holding unit for rotating the substrate around a central axis of the substrate while holding the substrate in a horizontal position; a pretreatment liquid discharge nozzle for supplying a pretreatment liquid to the rotating substrate so as to reduce a contact angle of a coating liquid for forming the coating film with the upper surface of the rotating substrate, and forming a liquid film of the pretreatment liquid in a circular coating area having the same width as a target width for forming the coating film on the upper surface of the peripheral portion of the substrate; and a coating liquid discharge nozzle for supplying the coating liquid onto the liquid film of the pretreatment liquid formed on the upper surface of the peripheral portion of the rotating substrate, to form the coating film.

[0014] In an eighth aspect, in the substrate processing apparatus according to the sixth or seventh aspect, the pre-treatment liquid discharge nozzle supplies the pre-treatment liquid to the underside of the peripheral portion of the substrate, and causes the pre-treatment liquid to flow from the edge of the substrate to the upper surface of the peripheral portion.

[0015] In a ninth aspect, in the substrate processing apparatus according to the sixth or seventh aspect, the rotating holder rotates the substrate at 500 rpm or more while the pre-treatment liquid discharge nozzle supplies the pre-treatment liquid to an upper surface of a peripheral portion of the substrate, so that the pre-treatment liquid is applied to the coating area in multiple overlapping layers.

[0016] In a tenth aspect, in the substrate processing apparatus according to the sixth or seventh aspect, the pretreatment liquid is a liquid containing propylene glycol monomethyl ether acetate or propylene glycol monomethyl ether. Effect of the Invention

[0017] According to the substrate processing methods of the first and third to fifth aspects, a liquid film of a pre-treatment liquid containing a solvent for the coating liquid is formed in a circular coating region on the upper surface of the peripheral portion of the substrate, the width of the region being the same as a target width for forming the coating film, and a coating liquid is supplied onto the liquid film of the pre-treatment liquid to form the coating film. Therefore, the coating liquid spreads in the same region as the liquid film of the pre-treatment liquid, and a coating film of uniform width can be formed.

[0018] According to the substrate processing methods of the second to fifth aspects, a liquid film of pre-treatment liquid that reduces the contact angle of the coating liquid with respect to the upper surface of the substrate is formed in a circular coating region on the upper surface of the peripheral portion of the substrate, the width of the region being the same as the target width for forming the coating film, and a coating liquid is supplied onto the liquid film of pre-treatment liquid to form the coating film. Therefore, the coating liquid spreads in the same region as the liquid film of the pre-treatment liquid, and a coating film of uniform width can be formed.

[0019] In particular, according to the substrate processing method of the third aspect, the pre-processing liquid is supplied to the underside of the peripheral edge of the rotating substrate and flows around from the edge of the substrate to the upper surface of the peripheral edge, thereby making it possible to make the width of the liquid film of the pre-processing liquid uniform.

[0020] In particular, according to the substrate processing method of the fourth aspect, while rotating the substrate at 500 rpm or more, the pretreatment liquid is supplied to the upper surface of the peripheral portion of the substrate so that the pretreatment liquid is applied to the coating region in multiple overlapping layers, thereby making it possible to make the width of the liquid film of the pretreatment liquid uniform.

[0021] According to the substrate processing apparatus of the sixth and eighth to tenth aspects, a liquid film of a pre-treatment liquid containing a solvent for the coating liquid is formed in a circular coating area on the upper surface of the peripheral portion of the substrate, the width of the area being the same as the target width for forming the coating film, and a coating liquid is supplied onto the liquid film of the pre-treatment liquid to form the coating film. Therefore, the coating liquid spreads in the same area as the liquid film of the pre-treatment liquid, and a coating film of uniform width can be formed.

[0022] According to the substrate processing apparatus of the seventh to tenth aspects, a liquid film of pre-treatment liquid that reduces the contact angle of the coating liquid with respect to the upper surface of the substrate is formed in a circular coating area on the upper surface of the peripheral portion of the substrate, the width of the area being the same as the target width for forming the coating film, and a coating liquid is supplied onto the liquid film of pre-treatment liquid to form the coating film. Therefore, the coating liquid spreads in the same area as the liquid film of the pre-treatment liquid, and a coating film of uniform width can be formed.

[0023] In particular, according to the substrate processing apparatus of the eighth aspect, the pre-treatment liquid is supplied to the underside of the peripheral portion of the substrate and flows around from the edge of the substrate to the upper surface of the peripheral portion, thereby making it possible to make the width of the liquid film of the pre-treatment liquid uniform.

[0024] In particular, according to the substrate processing apparatus of the ninth aspect, while rotating the substrate at 500 rpm or more, the pretreatment liquid is supplied to the upper surface of the peripheral portion of the substrate so that the pretreatment liquid is applied to the coating region in multiple overlapping layers, thereby making it possible to make the width of the liquid film of the pretreatment liquid uniform. [Brief description of the drawings]

[0025] [Figure 1] 1 is a diagram showing a schematic configuration of a substrate processing apparatus according to the present invention; [Diagram 2] 2 is a flowchart showing a procedure of a processing operation in the substrate processing apparatus of FIG. [Diagram 3] 3A to 3C are diagrams illustrating the formation of a liquid film of a pretreatment liquid. [Figure 4] 4A to 4C are diagrams illustrating the adjustment of the thickness of a liquid film of a pretreatment liquid. [Diagram 5] FIG. 2 is a plan view of a substrate on which a liquid film of a pretreatment liquid has been formed. [Figure 6] FIG. 2 is a diagram showing a schematic diagram of the formation of a coating film. [Figure 7] FIG. 2 is a diagram illustrating the drying of a coating film. [Figure 8] 1A and 1B are diagrams illustrating cleaning of the rear surface of a substrate. [Figure 9] FIG. 13 is a diagram showing a schematic configuration of a main part of a substrate processing apparatus according to a second embodiment. [Figure 10] 11A to 11C are diagrams illustrating the formation of a liquid film of a pretreatment liquid in a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] Hereinafter, the embodiments of the present invention will be described in detail 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.) not only strictly indicate the positional relationship, but also indicate a state in which the relative angle or distance is displaced within a range in which a tolerance or similar function is obtained, unless otherwise specified. Furthermore, expressions indicating an equal state (e.g., "same," "equal," "homogeneous," etc.) not only indicate a state in which the relative position is strictly equal quantitatively, but also indicate a state in which there is a difference in which a tolerance or similar function is obtained, unless otherwise specified. Furthermore, expressions indicating a shape (e.g., "circular," "square," "cylindrical," etc.) not only indicate a geometrically strict shape, but also indicate a shape within a range in which a similar effect is obtained, and may have, for example, unevenness or chamfering. Furthermore, each expression such as "comprises," "includes," "has," "includes," and "has" for a component is not an exclusive expression that excludes the presence of other components. In addition, 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."

[0027] First Embodiment Fig. 1 is a diagram showing a schematic configuration of a substrate processing apparatus 1 according to the present invention. The substrate processing apparatus 1 in Fig. 1 is a coating apparatus (spin coater) that rotates a disk-shaped substrate W and supplies a predetermined coating liquid to the peripheral edge of the substrate W to form a coating film. The substrate W to be processed is, for example, a silicon semiconductor wafer. The size of the semiconductor wafer is not particularly limited, but is, for example, φ300 mm or φ450 mm (φ300 mm in this embodiment).

[0028] The substrate processing apparatus 1 includes, as its main components, a rotation holder 10, a first nozzle 20, and a second nozzle 30. The substrate processing apparatus 1 also includes a control unit 50 that controls various operating mechanisms provided therein to cause the processing of the substrate W to proceed.

[0029] The spin holder 10 includes a spin chuck 11 and a spin motor 12. The spin chuck 11 is a substrate holder 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 vertically). The spin chuck 11 is, for example, a vacuum suction type chuck. The spin chuck 11 has a disk shape with a diameter smaller than the diameter of the substrate W. The spin chuck 11 suction-holds the center of the lower surface of the substrate W. When the lower surface of the substrate W is suction-held by the spin chuck 11, the peripheral edge of the substrate W protrudes outward beyond the outer circumferential end of the spin chuck 11. The spin chuck 11 may be another type of chuck, such as a clamping type mechanical chuck.

[0030] The spin chuck 11 is connected to the spin motor 12 via a motor shaft. That is, an upper end of the motor shaft of the spin motor 12 is connected to the center of the lower surface of the spin chuck 11. When the spin motor 12 rotates the motor shaft while the substrate W is attracted and held by the spin chuck 11, the substrate W and the spin chuck 11 rotate in a horizontal plane around the central axis X of the substrate W aligned in the vertical direction.

[0031] A cup 40 is provided so as to surround the periphery of the spin chuck 11. The cup 40 can be raised and lowered by a lifting mechanism (not shown). The cup 40 has a cylindrical shape, and the upper part of the cup 40 is inclined so as to approach the spin chuck 11 as it goes upward. However, the inner diameter of the upper end part of the cup 40 is larger than the diameter of the substrate W. When the substrate W is processed, the upper end of the cup 40 is higher than the height position of the substrate W held by the spin chuck 11. Therefore, liquid scattered by centrifugal force from the substrate W rotated by the spin motor 12 is received and collected by the cup 40. The liquid collected by the cup 40 is discharged from a drainage pipe provided at the bottom of the cup 40. The cup 40 may have a multi-stage structure in which a plurality of collection ports are provided for different purposes.

[0032] The first nozzle 20 is a pre-treatment liquid discharge nozzle that discharges a pre-treatment liquid onto the substrate W held by the spin chuck 11. In the first embodiment, the first nozzle 20 is disposed above the substrate W held by the spin chuck 11. The first nozzle 20 is connected to a pre-treatment liquid supply unit 21 via a pipe. The pre-treatment liquid supply unit 21 delivers the pre-treatment liquid to the first nozzle 20. The pre-treatment liquid will be described in further detail below, and is, for example, a liquid containing PGMEA (propylene glycol monomethyl ether acetate) or PGME (propylene glycol monomethyl ether).

[0033] 1, the first nozzle 20 can be moved back and forth between above the center and above the peripheral edge of the substrate W held by the spin chuck 11. The first nozzle driving mechanism 22 may be a mechanism for moving the first nozzle 20 along an arc-shaped trajectory (a mechanism for rotating a nozzle arm), or may be a mechanism for moving the first nozzle 20 linearly along the radial direction of the substrate W (a linear driving mechanism). The first nozzle driving mechanism 22 can also move the first nozzle 20 to a standby position outside the cup 40.

[0034] On the other hand, the second nozzle 30 is a coating liquid discharge nozzle that discharges a coating liquid onto the substrate W held by the spin chuck 11. The second nozzle 30 is connected to a coating liquid supply unit 31 via a pipe. The coating liquid supply unit 31 delivers the coating liquid of the second nozzle 30. The coating liquid in this embodiment is a processing liquid that forms a coating film that functions as a protective film having resistance to etching processes such as DRIE by drying, and for example, a liquid for forming a photoresist or an underlayer film is used. Examples of the liquid for forming the underlayer film include SOG liquid (Spin-on-Glass) containing a silicon-containing polymer and SOC liquid (Spin-on-Carbon) containing a carbon-containing polymer.

[0035] 1, the second nozzle 30 can be moved back and forth between above the center and above the peripheral portion of the substrate W held by the spin chuck 11. Like the first nozzle driving mechanism 22, the second nozzle driving mechanism 32 may be a mechanism that moves the second nozzle 30 along an arc-shaped trajectory, or may be a mechanism that moves the second nozzle 30 linearly along the radial direction of the substrate W. The second nozzle driving mechanism 32 can also move the second nozzle 30 to a standby position outside the cup 40.

[0036] The substrate processing apparatus 1 also includes a back-rinse nozzle 60. The back-rinse nozzle 60 is fixedly installed below the substrate W held by the spin chuck 11. The back-rinse nozzle 60 is inclined so that the discharge direction is obliquely upward from the center side to the edge side of the substrate W. The back-rinse nozzle 60 discharges, as a rinse liquid, for example, PGMEA or a liquid containing PGME, or cyclohexane.

[0037] The control unit 50 controls various operating mechanisms provided in the substrate processing apparatus 1. The hardware configuration of the control unit 50 is similar to that of a general computer. That is, the control unit 50 includes a CPU which is a circuit that performs various arithmetic processing, a ROM which is a read-only memory that stores basic programs, a RAM which is a readable and writable memory that stores various information, and a storage unit (magnetic disk or SSD) that stores control software, data, and the like. The CPU of the control unit 50 executes a predetermined processing program to control the operations of the spin holder 10, the first nozzle 20, and the second nozzle 30, whereby the processing of the substrate W in the substrate processing apparatus 1 proceeds.

[0038] Next, the processing operation in the substrate processing apparatus 1 will be described. FIG. 2 is a flow chart showing the procedure of the processing operation in the substrate processing apparatus 1. Prior to being carried into the substrate processing apparatus 1, a resist film is formed on the substrate W by a coating and developing apparatus (coater-developer) provided separately from the substrate processing apparatus 1, and the resist film after pattern exposure is subjected to a development process to form a pattern. In order to prevent dust generation due to contact between the edge of the substrate W on which the resist film is formed and the transport arm or the positioning unit, the resist film is removed from the peripheral portion of the substrate W immediately after the resist film is formed. Therefore, the silicon base material is exposed at the peripheral portion of the substrate W.

[0039] The substrate W, on which a pattern has been formed and from which the resist film has been removed from its peripheral portion, is carried into the substrate processing apparatus 1 by a transfer robot (not shown) and held by the spin holder 10 (step S1). The spin chuck 11 of the spin holder 10 adsorbs the central portion of the lower surface of the substrate W and holds the substrate W in a horizontal position.

[0040] Next, the spin holder 10 starts to rotate the substrate W held in a horizontal position (step S2). The spin motor 12 of the spin holder 10 rotates the substrate W around the central axis X of the substrate W within a horizontal plane.

[0041] After the rotation speed of the substrate W reaches a predetermined number, a pretreatment liquid is supplied from the first nozzle 20 to the peripheral portion of the substrate W to form a liquid film (step S3). In this embodiment, the first nozzle 20 supplies a liquid containing, for example, PGMEA or PGME as the pretreatment liquid. The peripheral portion of the substrate W refers to a region outside (on the edge side) of the region where the pattern is formed, and more specifically, a region 3 mm or less from the edge of the substrate W toward the center.

[0042] 3 is a diagram showing a schematic diagram of the formation of a liquid film of the pretreatment liquid. More specifically, the first nozzle 20 first ejects the pretreatment liquid downward while moving from the outside to the center of the rotating substrate W, and stops directly above a predetermined position on the top surface of the substrate W. The predetermined position is a position determined as the position closest to the substrate center of the coating film to be formed in a later process. Note that the predetermined position is exaggerated in FIG. 3 for ease of understanding, but the predetermined position is an appropriate position that is 1 mm to 3 mm from the edge of the substrate W toward the center.

[0043] The first nozzle 20 supplies the pretreatment liquid for a certain period of time directly above the predetermined position, and then moves outwardly of the substrate W. The pretreatment liquid supplied from the first nozzle 20 flows so as to spread outward (toward the edge portion) from the predetermined position on the upper surface of the substrate W due to centrifugal force accompanying the rotation of the substrate W. As a result, a liquid film 70 of the pretreatment liquid is formed in an annular shape on the peripheral portion of the upper surface of the substrate W that is closer to the edge portion than the predetermined position. Since the predetermined position is the innermost portion (closer to the center of the substrate) where the coating film is to be formed, the liquid film 70 of the pretreatment liquid is formed in an annular coating region having the same width as the target width for forming the coating film on the upper surface of the peripheral portion of the substrate W.

[0044] Furthermore, the rotation speed of the substrate W when the pretreatment liquid is supplied from the first nozzle 20 to form the liquid film 70 can be set to an appropriate value. As the rotation speed of the substrate W increases, the pretreatment liquid is thrown off from the substrate W by centrifugal force, resulting in a thinner film of the liquid film 70, whereas as the rotation speed of the substrate W decreases, the film of the liquid film 70 increases. In the first embodiment, the rotation speed of the substrate W is set to 500 rpm or more, which is relatively high for the liquid film forming process. Even if the substrate W is rotated at a considerably high rotation speed, the liquid film 70 is formed without the pretreatment liquid being completely thrown off from the substrate W, as long as the pretreatment liquid is continuously supplied from the first nozzle 20 and the pretreatment liquid is continuously applied to the upper surface of the substrate W.

[0045] Furthermore, the substrate W is rotated at least one revolution or more while the pretreatment liquid is supplied to the peripheral portion of the substrate W from the first nozzle 20. That is, the pretreatment liquid is applied multiple times to the application area on the upper surface of the peripheral portion of the substrate W (reapplication).

[0046] Next, the control unit 50 controls the rotation speed and rotation time of the substrate W to adjust the film thickness of the liquid film 70 of the pretreatment liquid (step S4). FIG. 4 is a diagram showing a schematic view of the film thickness adjustment of the liquid film 70 of the pretreatment liquid. Specifically, the control unit 50 controls the operation of the spin motor 12 so that the rotation speed and rotation time of the substrate W are preset values. The film thickness adjustment in step S4 makes the liquid film 70 of the pretreatment liquid uniformly thin. Note that the rotation of the substrate W in step S4 dries the liquid film 70 of the pretreatment liquid to some extent, but does not dry completely. That is, the liquid film 70 of the pretreatment liquid maintains a liquid phase state.

[0047] Through the processes of step S3 and step S4, a liquid film 70 of the pretreatment liquid with a width d1 is formed on the upper surface of the peripheral edge of the substrate W. The width d1 of the liquid film 70 of the pretreatment liquid is the same as the target width of a coating film to be formed in a subsequent process. The thickness of the liquid film 70 of the pretreatment liquid formed on the upper surface of the peripheral edge of the substrate W is adjusted to an appropriate value by the rotation speed of the substrate W in step S4. In the first embodiment, the rotation speed of the substrate W in step S3 is relatively high, and the thickness of the liquid film 70 of the pretreatment liquid is accordingly thin, so that the thickness adjustment process of step S4 may be omitted.

[0048] 5 is a plan view of the substrate W on which a liquid film 70 of the pretreatment liquid is formed. While rotating the substrate W at a relatively high rotation speed of 500 rpm or more, the pretreatment liquid is supplied from the first nozzle 20 to the upper surface of the peripheral portion of the substrate W, and the pretreatment liquid is applied to the coating area in multiple overlapping layers, whereby a liquid film 70 of the pretreatment liquid with a uniform width d1 is formed in a circular ring shape on the upper surface of the peripheral portion of the substrate W. That is, by applying the pretreatment liquid in multiple layers while rotating the substrate W at a high rotation speed, the width of the liquid film 70 of the pretreatment liquid is made uniform. Note that the width of the liquid film 70 of the pretreatment liquid is the length of the liquid film 70 along the radial direction of the substrate W, and the same applies to the width of a coating film 80 described later.

[0049] Next, a coating liquid is supplied from the second nozzle 30 to form a coating film on the liquid film 70 of the pretreatment liquid (step S5). In this embodiment, the second nozzle 30 supplies a liquid for forming a photoresist or an underlayer film as the coating liquid.

[0050] FIG. 6 is a diagram showing the formation of a coating film. More specifically, the second nozzle 30 first ejects the coating liquid downward while moving from the outside to the center of the rotating substrate W, and stops just above a predetermined position on the upper surface of the substrate W. The predetermined position at this time is the same as the end of the liquid film 70 of the pretreatment liquid on the substrate center side, or a position slightly outside (on the edge side) of the substrate center side. The second nozzle 30 supplies the coating liquid for a certain period of time just above the predetermined position, and then moves toward the outside of the substrate W. The second nozzle 30 supplies the coating liquid on the liquid film 70 of the pretreatment liquid only while the substrate W rotates once. That is, the coating liquid is applied only once on the liquid film 70 on the upper surface of the peripheral part of the substrate W (one-time application). The coating liquid supplied from the second nozzle 30 flows so as to spread over the liquid film 70 of the pretreatment liquid due to the centrifugal force caused by the rotation of the substrate W. As a result, a coating film 80 is formed in a circular ring shape on the liquid film 70 of the pretreatment liquid. A part of the coating liquid supplied from the second nozzle 30 flows around from the edge portion of the substrate W to the peripheral portion of the lower surface.

[0051] In the first embodiment, the pretreatment liquid of the liquid film 70 formed as the base film of the coating film 80 is a liquid containing PGMEA or PGME. PGMEA and PGME are also used as solvents of the coating liquid for forming the coating film 80. Therefore, the affinity between the liquid film 70 of the pretreatment liquid and the coating liquid is extremely high, and as a result, the coating liquid supplied on the liquid film 70 of the pretreatment liquid becomes wettable, and the contact angle of the coating liquid with respect to the upper surface of the substrate becomes small. In other words, the pretreatment liquid is also a liquid that reduces the contact angle of the coating liquid with respect to the upper surface of the substrate. When the coating liquid is supplied on such a liquid film 70 of the pretreatment liquid, the coating liquid spreads so as to dissolve in the liquid film 70 of the pretreatment liquid. As a result, the coating liquid spreads in the same annular region as the liquid film 70 of the pretreatment liquid, and the width of the coating film 80 becomes equal to the width d1 of the liquid film 70 of the pretreatment liquid that was previously formed as the base film.

[0052] Furthermore, by supplying the coating liquid onto the liquid film 70 of the pretreatment liquid, the formation of the coating film 80 itself can be facilitated. Specifically, the peripheral edge of the substrate W may have been subjected to a change in the surface state in some previous processes, for example, a stepped shape may be formed. Even if a stepped shape is provided on the peripheral edge of the substrate W, the effect of the stepped shape can be mitigated by forming the liquid film 70 of the pretreatment liquid on the upper surface of the peripheral edge, and the coating film 80 can be easily formed.

[0053] Next, the coating film 80 formed on the peripheral portion of the substrate W is dried (step S6). FIG. 7 is a diagram showing the drying of the coating film 80. Specifically, the control unit 50 controls the operation of the spin motor 12 so that the rotation speed of the substrate W is significantly increased. The substrate W rotates at high speed, so-called spin drying is performed, and the coating film 80 is dried. Note that in FIG. 6, the interface between the liquid film 70 of the pretreatment liquid and the coating film 80 is clearly shown for ease of understanding, but as described above, the pretreatment liquid is also a solvent for the coating liquid, and when the coating liquid is supplied onto the liquid film 70 of the pretreatment liquid, the two immediately mix and become one. As a result, as shown in FIG. 7, in the drying process of step S6, a single-layer, annular coating film 80 is formed on the upper surface of the peripheral portion of the substrate W.

[0054] Through the processes of steps S5 and S6, a coating film 80 having a width d1 is formed on the upper surface of the peripheral portion of the substrate W. The width d1 of this coating film 80 is the same as the width of the liquid film 70 of the pretreatment liquid formed through the processes of steps S3 and S4. The liquid film 70 of the pretreatment liquid is formed so that its width is the same as the target width of the coating film 80. Therefore, the width of the formed coating film 80 coincides with the target width.

[0055] After the drying process, the back surface of the substrate W is cleaned (step S7). FIG. 8 is a diagram showing the back surface cleaning of the substrate W. When the coating liquid is supplied to the peripheral portion of the rotating substrate W in step S5, a part of the coating liquid flows from the edge portion of the substrate W to the peripheral portion of the lower surface. The coating liquid that flows to the lower surface of the substrate W is dried in the drying process of step S6 and adheres to the lower surface as a coating film. In step S7, the coating film adhered to the lower surface of the substrate W is washed away. Specifically, while rotating the substrate W, a rinse liquid is discharged from the back rinse nozzle 60 onto the lower surface of the substrate W. The rinse liquid supplied to the lower surface of the substrate W flows along the lower surface of the substrate W toward the edge portion due to centrifugal force. The coating film adhered to the lower surface of the substrate W is washed away and removed by this flow of the rinse liquid.

[0056] Thereafter, the substrate W on which the coating film 80 has been formed is carried out from the substrate processing apparatus 1 by a transfer robot (not shown) (step S8). The substrate W carried out from the substrate processing apparatus 1 is subjected to a post-process, such as a DRIE process. In the DRIE process, the upper surface of the peripheral portion of the substrate W is protected by the coating film 80.

[0057] When the coating film 80 is directly formed without forming the liquid film 70 of the pretreatment liquid on the upper surface of the substrate W, the uniformity of the width of the coating film 80 is often deteriorated due to several factors as follows. First, when the coating liquid is discharged from the second nozzle 30, if the second nozzle 30 itself vibrates, the coating liquid discharged from the second nozzle 30 also vibrates, and the width of the coating film 80 becomes non-uniform. Second, the width of the coating film 80 also becomes non-uniform when the discharge state of the coating liquid discharged from the second nozzle 30 fluctuates. Third, the second nozzle 30 supplies the coating liquid onto the liquid film 70 of the pretreatment liquid only while the substrate W rotates once, and the width of the coating film 80 often becomes discontinuous at the start position of the supply of the coating liquid. Fourth, the substrate W, which is a disc-shaped semiconductor wafer, is provided with a notch (orientation flat in the case of a wafer with a diameter of 200 mm) for indicating the crystal orientation, and the width of the coating film 80 becomes non-uniform at the notch portion. Fifthly, if the center of the substrate W is eccentric from the rotation axis of the spin motor 12, the uniformity of the width of the coating film 80 deteriorates due to the effect of the eccentricity.

[0058] In the first embodiment, first, the pretreatment liquid is supplied to the upper surface of the peripheral portion of the substrate W to form a liquid film 70 of the pretreatment liquid, and then the coating liquid is supplied onto the liquid film 70 to form a coating film 80. When forming the liquid film 70 of the pretreatment liquid, the substrate W is rotated at a relatively high rotation speed of 500 rpm or more, and the pretreatment liquid is applied to the upper surface of the peripheral portion of the substrate W in multiple overlapping layers, thereby forming the liquid film 70 of the pretreatment liquid with a uniform width d1. The affinity between the liquid film 70 of the pretreatment liquid and the coating liquid is extremely high, and the coating liquid spreads to the same annular region as the liquid film 70 of the pretreatment liquid was formed, thereby forming the coating film 80. That is, the width of the coating film 80 becomes the same as the width of the liquid film 70 of the pretreatment liquid, and is uniform.

[0059] Therefore, by uniformly forming the liquid film 70 of the pretreatment liquid with the same width d1 as the target width of the coating film 80 to be formed, it is possible to form the coating film 80 with a uniform target width. Since the affinity between the liquid film 70 of the pretreatment liquid and the coating liquid is extremely high, even if there are factors that deteriorate uniformity as described above, the coating liquid spreads to blend with the liquid film 70, and the width of the coating film 80 can be made uniform, as long as the width of the liquid film 70 of the pretreatment liquid is uniform. For example, even if vibration occurs in the second nozzle 30, as long as the width of the liquid film 70 of the pretreatment liquid is uniform, the coating liquid spreads to blend with the liquid film 70 of the pretreatment liquid, and the coating film 80 with a uniform width can be formed.

[0060] As a prerequisite for such a technique, it is necessary to form the liquid film 70 of the pretreatment liquid with a uniform width. It is significantly easier to form the liquid film 70 of the pretreatment liquid with a uniform width than to directly discharge the coating liquid onto the substrate W to form the coating film 80 with a uniform width. The reason is that it is quite difficult to form the coating film 80 with a uniform width by coating the peripheral portion of the substrate W only once with a coating liquid having a higher viscosity than the pretreatment liquid. In contrast, it is significantly easier to form the liquid film 70 with a uniform width by depositing the relatively low-viscosity pretreatment liquid on the peripheral portion of the substrate W in multiple overlapping portions while rotating the substrate W at a relatively high rotation speed of 500 rpm or more. In this way, even if the center of the substrate W is eccentric from the rotation axis of the spin motor 12, the liquid film 70 with a uniform width can be formed. Furthermore, the first nozzle 20 that ejects the pretreatment liquid has a higher degree of freedom in nozzle structure than the second nozzle 30 that ejects the coating liquid, and furthermore, the ejection rate of the pretreatment liquid is easier to adjust. For these reasons, too, it is easier to form the liquid film 70 of the pretreatment liquid with a uniform width.

[0061] To summarize, in the first embodiment, the pretreatment liquid is applied in layers multiple times onto the upper surface of the peripheral portion of the substrate W while the substrate W is rotated at a relatively high rotation speed of 500 rpm or more, to form a uniform-width circular liquid film 70 of the pretreatment liquid. Then, by supplying a coating liquid onto the liquid film 70, the coating liquid is spread over the same circular region as the liquid film 70 to form a coating film 80 of uniform width.

[0062] <Second embodiment> Next, a second embodiment of the present invention will be described. In the second embodiment, a first nozzle 20 for discharging a pre-treatment liquid is provided below the substrate W held by the spin chuck 11, and the pre-treatment liquid supplied to the lower surface of the peripheral edge of the rotating substrate W is caused to flow around from the edge of the substrate W to the upper surface of the peripheral edge.

[0063] Fig. 9 is a diagram showing a schematic configuration of a main part of a substrate processing apparatus according to the second embodiment. In Fig. 9, the same elements as those in the first embodiment (Fig. 1) are given the same reference numerals. In the first embodiment, the first nozzle 20 is provided above the substrate W held by the spin chuck 11, whereas in the second embodiment, the first nozzle 20 for discharging the pre-processing liquid is provided below the substrate W. In the second embodiment, the first nozzle 20 may be fixed. The first nozzle 20 in the second embodiment is provided at an angle so that the discharge direction faces the edge of the substrate W. The remaining configuration of the second embodiment, except for the shape of the first nozzle 20, is the same as that of the first embodiment.

[0064] The processing procedure for the substrate W in the second embodiment is generally the same as that in the first embodiment (FIG. 2). That is, after the substrate W is held by the spin chuck 11 of the spin holder 10, the rotation of the substrate W is started. Then, the pre-processing liquid is discharged from the first nozzle 20 provided below the substrate W to form a liquid film 70 of the pre-processing liquid on the peripheral edge of the substrate W. In the liquid film forming process of step S3, the pre-processing liquid is supplied to the underside of the peripheral edge of the rotating substrate W.

[0065] FIG. 10 is a diagram showing the formation of a liquid film of the pretreatment liquid in the second embodiment. The pretreatment liquid supplied from the first nozzle 20 to the lower surface of the peripheral portion of the rotating substrate W flows toward the edge of the substrate W due to the centrifugal force. Then, a part of the pretreatment liquid that has reached the edge of the substrate W flows from the edge to the upper surface of the peripheral portion due to the surface tension of the substrate W. As a result, a small area of ​​a certain width from the edge to the center of the upper surface of the substrate W is covered with the pretreatment liquid. The size of the width is determined by the balance between the surface tension of the substrate W and the centrifugal force. As a result, a liquid film 70 of the pretreatment liquid of a certain width is formed in a circular shape on the upper surface of the peripheral portion of the substrate W, as in the first embodiment. However, since a part of the pretreatment liquid is scattered from the substrate W due to the centrifugal force, the amount of the pretreatment liquid consumed is greater than that of the first embodiment.

[0066] The process from step S4 onwards is the same as that in the first embodiment. That is, after the thickness of the liquid film 70 of the pretreatment liquid is adjusted, a coating liquid is supplied onto the liquid film 70 of the pretreatment liquid to form a coating film 80. Thereafter, the coating film 80 is dried, and then the back surface of the substrate W is cleaned.

[0067] In the second embodiment, the pretreatment liquid is supplied to the lower surface of the peripheral portion of the substrate W, and the pretreatment liquid is caused to flow from the edge of the substrate W to the upper surface of the peripheral portion, thereby forming a liquid film 70 of the pretreatment liquid in a circular ring shape on the upper surface of the peripheral portion. The width of the liquid film 70 of the pretreatment liquid is determined by the balance between the surface tension of the substrate W and the centrifugal force. Therefore, even if the center of the substrate W is eccentric from the rotation axis of the spin motor 12, for example, the width of the liquid film 70 of the pretreatment liquid can be made uniform. By supplying a coating liquid onto the liquid film 70 of the pretreatment liquid formed to a uniform width, it is possible to form a coating film 80 of a uniform width in a circular ring shape, as in the first embodiment.

[0068] <Modification> Although the embodiments of the present invention have been described above, this invention can be modified in various ways without departing from the spirit of the invention. For example, in each of the above embodiments, a liquid containing PGMEA or PGME is used as the pretreatment liquid, but the pretreatment liquid is not limited to this, and may be any liquid containing a solvent for the coating liquid or a liquid that reduces the contact angle of the coating liquid with the upper surface of the substrate. Therefore, it is preferable to select an appropriate liquid as the pretreatment liquid according to the type of coating film to be formed.

[0069] In addition, in each of the above embodiments, a resist film or an underlayer film is formed as the coating film 80, but the present invention is not limited to this and any film having resistance to etching treatment such as DRIE may be used.

[0070] Furthermore, in each of the above embodiments, the coating liquid is applied only once onto the liquid film 70 on the upper surface of the peripheral portion of the substrate W, but the coating liquid may be applied two or three times.

[0071] In addition, when the center of the substrate W is eccentric from the rotation axis of the spin motor 12, the first nozzle 20 may be operated to follow the eccentricity, thereby forming a liquid film 70 of the pre-treatment liquid with a uniform width.

[0072] In the first embodiment, the pre-treatment liquid is ejected vertically downward from the first nozzle 20, but instead, the pre-treatment liquid may be ejected obliquely downward (toward the edge of the substrate W) from the first nozzle 20. Similarly, the coating liquid may be ejected obliquely downward from the second nozzle 30. [Explanation of symbols]

[0073] 1. Substrate Processing Equipment 10 Rotational support part 11 Spin chuck 12 Spin motor 20 No. 1 nozzle 30 No. 2 nozzle 40 cups 50 Control section 60 Back rinse nozzle 70 Liquid film 80 Coating film W substrate

Claims

1. A substrate processing method for forming a coating film on a peripheral portion of a disk-shaped substrate, comprising the steps of: a pretreatment liquid film forming step of supplying a pretreatment liquid containing a solvent of a coating liquid for forming the coating film onto the substrate while rotating the substrate within a horizontal plane, and forming a liquid film of the pretreatment liquid in an annular coating region having the same width as a target width for forming the coating film on the upper surface of the peripheral portion of the substrate; a coating film forming step of supplying the coating liquid onto the liquid film of the pretreatment liquid while rotating the substrate in a horizontal plane to form the coating film; A substrate processing method comprising:

2. A substrate processing method for forming a coating film on a peripheral portion of a disk-shaped substrate, comprising the steps of: a pretreatment liquid film forming step of supplying a pretreatment liquid for reducing a contact angle of a coating liquid for forming the coating film on the upper surface of the substrate while rotating the substrate in a horizontal plane, and forming a liquid film of the pretreatment liquid in an annular coating region having the same width as a target width for forming the coating film on the upper surface of the peripheral portion of the substrate; a coating film forming step of supplying the coating liquid onto the liquid film of the pretreatment liquid while rotating the substrate in a horizontal plane to form the coating film; A substrate processing method comprising:

3. 3. The substrate processing method according to claim 1, further comprising: In the pretreatment liquid film forming step, the pretreatment liquid is supplied to a lower surface of the peripheral portion of the substrate, and the pretreatment liquid is allowed to flow from the edge portion of the substrate to an upper surface of the peripheral portion.

4. 3. The substrate processing method according to claim 1, further comprising: In the pretreatment liquid film forming step, the substrate is rotated at 500 revolutions per minute or more while the pretreatment liquid is supplied to the upper surface of the peripheral portion of the substrate, so that the pretreatment liquid is applied to the coating area in multiple overlapping layers.

5. 3. The substrate processing method according to claim 1, further comprising: The substrate processing method, wherein the pretreatment liquid is a liquid containing propylene glycol monomethyl ether acetate or propylene glycol monomethyl ether.

6. A substrate processing apparatus for forming a coating film on a peripheral portion of a disk-shaped substrate, a rotation holder that holds the substrate in a horizontal position and rotates the substrate around a central axis of the substrate; a pretreatment liquid discharge nozzle that supplies a pretreatment liquid containing a solvent for a coating liquid for forming the coating film onto the rotating substrate, and forms a liquid film of the pretreatment liquid in an annular coating region having the same width as a target width for forming the coating film on the upper surface of the peripheral portion of the substrate; a coating liquid discharge nozzle that supplies the coating liquid onto a liquid film of the pretreatment liquid formed on an upper surface of a peripheral portion of the rotating substrate to form the coating film; A substrate processing apparatus comprising:

7. A substrate processing apparatus for forming a coating film on a peripheral portion of a disk-shaped substrate, a rotation holder that holds the substrate in a horizontal position and rotates the substrate around a central axis of the substrate; a pretreatment liquid discharge nozzle that supplies a pretreatment liquid to the rotating substrate to reduce a contact angle of a coating liquid for forming the coating film with respect to the upper surface of the substrate, and forms a liquid film of the pretreatment liquid in an annular coating region having the same width as a target width for forming the coating film on the upper surface of the peripheral portion of the substrate; a coating liquid discharge nozzle that supplies the coating liquid onto a liquid film of the pretreatment liquid formed on an upper surface of a peripheral portion of the rotating substrate to form the coating film; A substrate processing apparatus comprising:

8. 8. The substrate processing apparatus according to claim 6, The pre-treatment liquid discharge nozzle supplies the pre-treatment liquid to a lower surface of a peripheral portion of the substrate, and causes the pre-treatment liquid to flow from the edge portion of the substrate to an upper surface of the peripheral portion.

9. 8. The substrate processing apparatus according to claim 6, The substrate processing apparatus includes a pretreatment liquid discharge nozzle that supplies the pretreatment liquid to an upper surface of a peripheral portion of the substrate while the rotary holder rotates the substrate at 500 revolutions per minute or more, thereby applying the pretreatment liquid to the coating region in a plurality of overlapping layers.

10. 8. The substrate processing apparatus according to claim 6, The substrate processing apparatus, wherein the pretreatment liquid is a liquid containing propylene glycol monomethyl ether acetate or propylene glycol monomethyl ether.

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