Substrate processing method and substrate processing device

Abstract

To provide a substrate processing method and a substrate processing device that can reduce a hump generated when a coating film is formed.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 of the pretreatment liquid, 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. By supplying the coating liquid onto the liquid film 70 of the pretreatment liquid, the contact angle of the coating liquid to the upper surface of the substrate W is reduced, and a hump whose thickness becomes larger than that in the other region when the coating film 80 is formed can be reduced.SELECTED DRAWING: Figure 8

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. However, when the coating liquid is supplied to the peripheral portion of the substrate, the film thickness increases toward the center of the substrate, resulting in a phenomenon in which the thickness of the coating film becomes uneven. The portion where the film thickness is thicker than other regions is called a hump. When a hump occurs, problems occur, such as cracks occurring only in the hump portion during the baking process, or only the hump portion remains as a residue after etching.

[0006] The present invention has been made in consideration of the above problems, and has an object to provide a substrate processing method and a substrate processing apparatus that are capable of reducing humps that occur during formation of a coating film. [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, which reduces a contact angle of a coating liquid for forming the coating film with respect to an upper surface of the peripheral portion of the substrate while rotating the substrate in a horizontal plane, to form a liquid film of the pretreatment liquid; and a coating film formation step of supplying the coating liquid onto the liquid film of the pretreatment liquid while rotating the substrate in the 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 forming step of supplying a pre-treatment liquid containing a solvent of a coating liquid for forming the coating film onto an upper surface of the peripheral portion of the substrate while rotating the substrate in a horizontal plane, to form a liquid film of the pre-treatment liquid; and a coating film forming step of supplying the coating liquid onto the liquid film of the pre-treatment liquid while rotating the substrate in a horizontal plane, to form the coating film.

[0009] In addition, a third aspect is a substrate processing method according to the first or second aspect, further comprising a film thickness adjusting step of rotating the substrate in a horizontal plane after the pre-treatment liquid film forming step to uniformize a film thickness of the liquid film of the pre-treatment liquid.

[0010] In addition, a fourth aspect is the substrate processing method according to the first or second aspect, further comprising, after the coating film forming step, a drying step of rotating the substrate in a horizontal plane to dry the coating film.

[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 rotating holding unit for rotating the substrate around a central axis of the substrate while holding the substrate in a horizontal position; a pre-treatment liquid discharge nozzle for supplying a pre-treatment liquid onto an upper surface of the peripheral portion of the rotating substrate, the pre-treatment liquid reducing a contact angle of a coating liquid for forming the coating film with the upper surface, thereby forming a liquid film of the pre-treatment liquid; and a coating liquid discharge nozzle for supplying the coating liquid onto the liquid film of the pre-treatment liquid formed on the upper surface of the peripheral portion of the rotating substrate, thereby forming 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 pre-treatment liquid discharge nozzle for supplying a pre-treatment liquid containing a solvent of a coating liquid for forming the coating film onto an upper surface of the peripheral portion of the rotating substrate to form a liquid film of the pre-treatment liquid; and a coating liquid discharge nozzle for supplying the coating liquid onto the liquid film of the pre-treatment liquid formed on the upper surface of the peripheral portion of the rotating substrate to form the coating film.

[0014] In addition, an eighth aspect is a substrate processing apparatus according to the sixth or seventh aspect, wherein after a liquid film of the pre-treatment liquid is formed, the rotating holder rotates the substrate to make the thickness of the liquid film of the pre-treatment liquid uniform.

[0015] According to a ninth aspect, in the substrate processing apparatus according to the sixth or seventh aspect, after the coating film is formed, the spin holder rotates the substrate to dry the coating film.

[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 pre-treatment liquid that reduces the contact angle with the upper surface of the peripheral portion of the substrate is supplied to form a liquid film of the pre-treatment liquid, and then a coating liquid is supplied on top of the pre-treatment liquid to form a coating film. This reduces the contact angle of the coating liquid with the upper surface of the substrate and reduces humps that are thicker than other areas when the coating film is formed.

[0018] According to the substrate processing methods of the second to fifth aspects, a pre-treatment liquid containing a solvent for a coating liquid is supplied to the upper surface of the peripheral portion of the substrate to form a liquid film of the pre-treatment liquid, and then a coating liquid is supplied on top of the pre-treatment liquid to form a coating film. This reduces the contact angle of the coating liquid with the upper surface of the substrate and reduces humps, which are thicker than other areas when the coating film is formed.

[0019] According to the substrate processing apparatus of the sixth and eighth to tenth aspects, a pre-treatment liquid that reduces the contact angle with the upper surface of the peripheral portion of the substrate is supplied to form a liquid film of the pre-treatment liquid, and then a coating liquid is supplied on top of the pre-treatment liquid to form a coating film. This reduces the contact angle of the coating liquid with the upper surface of the substrate, thereby reducing humps that are thicker than other areas when the coating film is formed.

[0020] According to the substrate processing apparatus of the seventh to tenth aspects, a pre-treatment liquid containing a solvent for a coating liquid is supplied to the upper surface of the peripheral portion of the substrate to form a liquid film of the pre-treatment liquid, and then a coating liquid is supplied on top of the pre-treatment liquid to form a coating film. This reduces the contact angle of the coating liquid with the upper surface of the substrate and reduces humps, which are thicker than other areas when the coating film is formed. [Brief description of the drawings]

[0021] [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 diagram showing a schematic diagram of the formation of a coating film. [Figure 6] FIG. 1 is a diagram for explaining a contact angle. [Figure 7] FIG. 2 is a diagram showing a schematic state in which a coating film is formed directly on the upper surface of a substrate. [Figure 8] FIG. 2 is a diagram illustrating a state in which a coating film is formed on a liquid film of a pretreatment liquid. [Figure 9] FIG. 2 is a diagram illustrating the drying of a coating film. [Figure 10] 1A and 1B are diagrams illustrating cleaning of the rear surface of a substrate. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] 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."

[0023] 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 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).

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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. 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).

[0029] 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 by a first nozzle driving mechanism 22 conceptually shown in Fig. 1. The first nozzle driving mechanism 22 may be a mechanism that moves the first nozzle 20 along an arc-shaped trajectory (a mechanism that rotates a nozzle arm), or may be a mechanism that moves the first nozzle 20 linearly along the radial direction of the substrate W (a linear driving mechanism).

[0030] 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.

[0031] The second nozzle 30 can be moved back and forth between above the center and above the peripheral edge of the substrate W held on the spin chuck 11 by a second nozzle driving mechanism 32 conceptually shown in Fig. 1. 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.

[0032] 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.

[0033] 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 magnetic disk for storing 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, thereby progressing the processing of the substrate W in the substrate processing apparatus 1.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] FIG. 3 is a diagram showing 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 at a predetermined position. The predetermined position is exaggerated in FIG. 3 for ease of understanding, but is an appropriate position that is 1 mm to 3 mm from the edge of the substrate W toward the center. The first nozzle 20 supplies the pretreatment liquid at the predetermined position for a certain period of time, and then moves toward the outside of the substrate W. The pretreatment liquid supplied from the first nozzle 20 flows on the upper surface of the substrate W so as to spread outward (toward the edge) from the predetermined position due to the centrifugal force caused by the rotation of the substrate W. As a result, a liquid film 70 of the pretreatment liquid is formed in a circular ring shape on the peripheral portion of the upper surface of the substrate W that is closer to the edge than the predetermined position.

[0039] The thickness of the liquid film 70 of the pre-treatment liquid formed on the upper surface of the peripheral portion of the substrate W in step S3 can be set to an appropriate value. As the rotation speed of the substrate W increases, the pre-treatment liquid is thrown off from the substrate W by centrifugal force, and the thickness of the liquid film 70 becomes thinner. That is, the rotation speed of the substrate W in step S3 may be decreased to increase the thickness of the liquid film 70 of the pre-treatment liquid, or the rotation speed of the substrate W may be increased to decrease the thickness of the liquid film 70 of the pre-treatment liquid. In this embodiment, the rotation speed of the substrate W is set to, for example, 100 rpm.

[0040] 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.

[0041] 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 portion of the substrate W. The width d1 of the liquid film 70 of the pretreatment liquid is equal to the distance from the above-mentioned predetermined position to the edge of the substrate W, and is equal to or greater than 1 mm and equal to or less than 3 mm. The thickness of the liquid film 70 of the pretreatment liquid formed on the upper surface of the peripheral portion of the substrate W is adjusted to an appropriate value by the rotation speed of the substrate W in step S4. Note that, when the rotation speed of the substrate W is increased in step S3 to appropriately thin the thickness of the liquid film 70 of the pretreatment liquid, the film thickness adjustment process of step S4 may be omitted.

[0042] 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.

[0043] FIG. 5 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 at a predetermined position. 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 at the predetermined position for a certain period of time, and then moves toward the outside of the substrate W. The coating liquid supplied from the second nozzle 30 flows so as to spread on the liquid film 70 of the pretreatment liquid due to the centrifugal force caused by the rotation of the substrate W. As a result, the coating film 80 is formed in a circular ring shape on the liquid film 70 of the pretreatment liquid. Note that a part of the coating liquid supplied from the second nozzle 30 flows around from the edge part of the substrate W to the peripheral part of the lower surface.

[0044] When a liquid is dropped onto a solid, a droplet is formed on the upper surface of the solid, and the degree to which the droplet swells is expressed as a contact angle. Figure 6 is a diagram for explaining the contact angle. A droplet 94 formed on the upper surface of a solid 93 becomes round due to the surface tension of the liquid. The angle θ between the tangent at the end point of this droplet 94 and the upper surface of the solid 93 is the contact angle. The surface tension γ of the solid 93 S , the surface tension of the droplet 94 γL , and the interfacial tension γ between the solid 93 and the liquid droplet 94 SL Between them, γ S =γ L cosθ+γ SL (Young's equation) holds true.

[0045] In general, it is said that the smaller the contact angle θ (the closer it is to 0°), the more widely the droplet 94 spreads over the upper surface of the solid 93 and the more likely it is to wet it. Conversely, it is said that the larger the contact angle θ (the closer it is to 180°), the more the droplet 94 is repelled from the upper surface of the solid 93 and the more difficult it is to wet it.

[0046] FIG. 7 is a schematic diagram showing a state where the coating film 80 is formed directly on the upper surface of the substrate W. At the end of the coating film 80 on the substrate center side, the Young's equation is satisfied between the surface tension of the substrate W, the surface tension of the coating film 80, and the interfacial tension between the substrate W and the coating film 80. In addition, since the substrate W is rotating, a centrifugal force acts on the coating film 80 toward the edge of the substrate W. At the interface between the coating film 80 and the substrate W, an adhesion force that causes the coating film 80 to adhere to the substrate W is also generated. Furthermore, at the end of the coating film 80 on the substrate center side, the solvent contained in the coating film 80 evaporates faster than other parts, so the surface tension is higher, and a force is generated at the end of the coating film 80 on the substrate center side that pulls the inside, as shown by the arrow AR7. This force causes the end of the coating film 80 on the substrate center side to rise, resulting in the formation of a hump 86 that is thicker than other regions. Therefore, the contact angle θ1 of the coating film 80 at the end of the substrate center side is relatively large. As described above, if the hump 86 occurs, problems may occur, for example, in the firing process where only the hump 86 cracks may occur, or only the hump 86 may remain as a residue after etching.

[0047] For this reason, in this embodiment, the pretreatment liquid is supplied to the upper surface of the peripheral portion of the substrate W before the coating liquid is supplied to form the liquid film 70, and the coating film 80 is formed on the liquid film 70 of the pretreatment liquid. FIG. 8 is a diagram showing a state in which the coating film 80 is formed on the liquid film 70 of the pretreatment liquid. The pretreatment liquid in this embodiment is a liquid containing PGMEA or PGME. PGMEA and PGME are also used as solvents for 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 is in a state in which it is easy to wet. That is, the contact angle of the coating liquid becomes small, and the contact angle θ2 of the coating film 80 at the end of the substrate center side becomes significantly smaller than the contact angle θ1 when the coating film 80 is formed directly on the substrate W. In other words, the pretreatment liquid is a liquid that reduces the contact angle of the coating liquid with respect to the upper surface of the substrate.

[0048] As shown in Fig. 8, the contact angle θ2 of the coating film 80 at the end of the substrate center side is reduced, and thus the hump can be significantly reduced compared to the case where the coating film 80 is formed directly on the substrate W (Fig. 7). Furthermore, by forming the coating film 80 on the liquid film 70 of the pretreatment liquid, the adhesion between the coating film 80 and the upper surface of the substrate W is relatively reduced, and the coating liquid is more likely to flow toward the edge of the substrate W due to the centrifugal force caused by rotation, which also contributes to the reduction of the hump. The reduction of the hump also prevents the above-mentioned problems caused by the hump. Note that not only the height of the hump but also the width of the hump along the radial direction of the substrate W is reduced.

[0049] 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.

[0050] Next, the coating film 80 formed on the peripheral portion of the substrate W is dried (step S6). FIG. 9 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 that so-called spin drying is performed, and the coating film 80 is dried. Note that in FIG. 5 and FIG. 8, 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 film 80, and when the coating film 80 is formed on the liquid film 70 of the pretreatment liquid, the two immediately mix and become one. As a result, as shown in FIG. 9, 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.

[0051] Through the processes of steps S5 and S6, a coating film 80 having a width d2 is formed on the upper surface of the peripheral portion of the substrate W. The width d2 of the coating film 80 is equal to the width d1 (FIG. 4) of the liquid film 70 of the pretreatment liquid, or is slightly smaller than the width d1 of the liquid film 70 of the pretreatment liquid. Conversely, it is preferable that the width d1 of the liquid film 70 of the pretreatment liquid formed in steps S3 and S4 is equal to the required width d2 of the coating film 80, or is slightly larger than the width d2. However, when the discharge position of the coating liquid is set outside the end of the liquid film 70 of the pretreatment liquid on the substrate center side, the coating film 80 tends to spread toward the substrate center so as to be equal to the width d1 of the liquid film 70 of the pretreatment liquid. For this reason, if the width d1 of the liquid film 70 of the pretreatment liquid is made excessively large, the width d2 of the coating film 80 in the final finish may be wider than the target value.

[0052] After the drying process, the back surface of the substrate W is cleaned (step S7). FIG. 10 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.

[0053] 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.

[0054] In this embodiment, before the coating liquid is supplied to the substrate W, a 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. The pretreatment liquid is a solvent for the coating liquid, and is a liquid that reduces the contact angle of the coating liquid with respect to the upper surface of the substrate. Then, the coating liquid is supplied onto the liquid film 70 of the pretreatment liquid to form a coating film 80. This reduces the contact angle of the coating liquid with respect to the upper surface of the substrate W, and can reduce humps that occur when the coating film 80 is formed.

[0055] Although the embodiment of the present invention has been described above, this invention can be modified in various ways without departing from the spirit of the invention. For example, in the above embodiment, 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.

[0056] In the above embodiment, 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.

[0057] In the above 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]

[0058] 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 onto an upper surface of a peripheral portion of the substrate while rotating the substrate within a horizontal plane, the pretreatment liquid reducing a contact angle of a coating liquid for forming the coating film with the upper surface, thereby forming a liquid film of the pretreatment liquid; 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 containing a solvent for a coating liquid for forming the coating film onto an upper surface of a peripheral portion of the substrate while rotating the substrate within a horizontal plane, thereby forming a liquid film of the pretreatment liquid; 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: The substrate processing method further comprises, after the pretreatment liquid film forming step, a film thickness adjusting step of rotating the substrate in a horizontal plane to make the film thickness of the pretreatment liquid uniform.

4. 3. The substrate processing method according to claim 1, further comprising: The substrate processing method further comprises, after the coating film forming step, a drying step of rotating the substrate in a horizontal plane to dry the coating film.

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 for supplying a pretreatment liquid onto an upper surface of a peripheral portion of the rotating substrate, the pretreatment liquid being configured to reduce a contact angle of a coating liquid for forming the coating film with respect to the upper surface, thereby forming a liquid film of the pretreatment liquid; 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 for supplying a pretreatment liquid containing a solvent for a coating liquid for forming the coating film onto an upper surface of a peripheral portion of the rotating substrate to form a liquid film of the pretreatment liquid; 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, After the liquid film of the pre-treatment liquid is formed, the spin holder rotates the substrate to make the thickness of the liquid film of the pre-treatment liquid uniform.

9. 8. The substrate processing apparatus according to claim 6, After the coating film is formed, the spin holder rotates the substrate to dry the coating film.

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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