JP2023043964A - Substrate coating device and substrate coating method - Google Patents

Abstract

To coat a treatment solution to a surface of a substrate in a uniform manner, by preventing excessive supply of the treatment solution in a substrate coating device that coats the treatment solution to the surface of the substrate while varying an overlapping distance between the discharge port and the substrate in the longitudinal direction when viewed from above in plan view.SOLUTION: As an overlap distance changes with a relative movement of a slit nozzle to the substrate, supply reduction operation is performed to reduce a supply amount of the treatment solution to the slit nozzle. This suppresses excessive supply of the treatment solution to the slit nozzle, and an appropriate amount of the treatment solution exists between the discharge port of the slit nozzle and the surface of the substrate. As a result, the treatment solution can be uniformly coated to the substrate surface.SELECTED DRAWING: Figure 8

Description

The present invention is applied to precision substrates such as glass substrates for FPDs such as liquid crystal display devices and organic EL display devices, semiconductor wafers, glass substrates for photomasks, substrates for color filters, substrates for recording disks, substrates for solar cells, and substrates for electronic paper. The present invention relates to a substrate coating technique for supplying and coating a processing liquid from a slit nozzle onto a substrate for an electronic device or a substrate for a semiconductor package (hereinafter simply referred to as "substrate").

The slit nozzle is moved relative to the substrate in a coating direction orthogonal to the longitudinal direction of the ejection port while separating the slit-shaped ejection port provided in the slit nozzle upward from the surface of the substrate by a separation distance. A substrate coating apparatus is known which applies a processing liquid to a substrate by discharging the processing liquid from a slit nozzle during this relative movement. Among them, there has been proposed a substrate coating apparatus capable of coating a processing liquid not only on a rectangular substrate but also on a circular semiconductor wafer, for example. As a typical example, a capillary-type substrate coating apparatus (see Patent Document 1) is known.

Patent No. 6272138

For example, when applying a processing liquid to a semiconductor wafer using the above-described conventional apparatus, the following problems may occur. In these devices, the distance between the surface of the substrate and the ejection port (hereinafter referred to as "coating gap") is kept constant during the coating process. On the other hand, the wetted range of the processing liquid supplied from the ejection port according to the position of the slit nozzle moving along the surface of the substrate (corresponding to the "overlapping range" in the embodiments described later) is continuous. change to More specifically, as shown in FIGS. 5 and 7, which will be described later, the wetted area gradually widens immediately after the start of coating and reaches a maximum at the center of the substrate. After passing through it, the wetted area gradually narrows. Then, when the slit nozzle passes above the end region of the semiconductor wafer in the moving direction of the slit nozzle (corresponding to an example of the "coating direction" of the present invention), the coating process is completed and the slit nozzle separates from the substrate.

During the second half of the coating process, that is, while the slit nozzle moves from the wide position (symbol P2 in FIG. 4 described later) to the position above the end of the substrate (symbol P3 in FIG. 4 described later), The overlapping distance between the ejection port and the substrate is reduced in the longitudinal direction in plan view from above. However, in the prior art, since the coating gap is kept constant, as will be described in detail later with reference to FIG. Excessive supply of the processing liquid in the longitudinal direction of the ejection port may occur. As a result, there has been a problem that the film thickness becomes thicker in the latter round portion (reference numeral PT4 in FIG. 4) of the surface peripheral portion of the substrate. Moreover, when applying a processing liquid that has the property of spreading relatively quickly on the surface of the substrate, the above problem may occur in the first half of the coating process (range where the overlapping distance increases).

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides a substrate coating apparatus that applies a processing liquid to the surface of a substrate while changing the overlapping distance between the discharge port and the substrate in the longitudinal direction in plan view from above. The object of the present invention is to uniformly apply the processing liquid to the surface of the substrate while preventing excessive supply of the processing liquid.

One aspect of the present invention is a substrate coating apparatus for coating a surface of a substrate with a treatment liquid, comprising a slit nozzle having a slit-shaped ejection opening facing the surface of the substrate, and a coating direction perpendicular to the longitudinal direction of the ejection opening. a moving unit for moving the slit nozzle relative to the substrate; a processing liquid supply unit configured to be able to supply the processing liquid to the slit nozzle as the slit nozzle moves relative to the substrate; a processing liquid supply unit; The processing liquid supply unit is capable of executing a supply reduction operation for reducing the amount of processing liquid supplied to the slit nozzle. The processing liquid supply unit is controlled such that the supply reduction operation is performed in accordance with the change in the lengthwise overlapping distance between the discharge port and the substrate as the slit nozzle moves relative to the substrate. and

In another aspect of the present invention, the processing liquid is ejected from a slit-shaped ejection port provided in the slit nozzle arranged above the surface of the substrate, and the slit nozzle is arranged in the longitudinal direction of the ejection port with respect to the substrate. A substrate coating method in which a treatment liquid is applied to the surface of a substrate by relatively moving in a coating direction perpendicular to the substrate, wherein the overlapping distance between the discharge port and the substrate in the longitudinal direction in a plan view from above is the slit nozzle with respect to the substrate. It is characterized by executing a supply reduction operation for reducing the supply amount of the processing liquid to the slit nozzle according to the change accompanying the relative movement of the slit nozzle.

If the supply amount is kept constant during the period in which the overlap distance changes with the relative movement of the slit nozzle with respect to the substrate, excessive supply of the processing liquid will cause the film thickness to decrease, as will be described later with reference to FIGS. increases (hereinafter referred to as "excess film thickness"). Therefore, in the present invention, the supply reduction operation is executed according to the change in the overlap distance. As a result, excessive supply is suppressed, and an appropriate amount of processing liquid exists between the ejection port of the slit nozzle and the surface of the substrate.

As described above, according to the present invention, in a substrate coating apparatus that coats the surface of a substrate with a processing liquid while changing the overlap distance, excessive supply of the processing liquid is prevented, and the processing liquid is spread uniformly over the surface of the substrate. can be applied.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows an example of the substrate processing apparatus which can apply 1st Embodiment of the board|substrate coating method which concerns on this invention. 1B is a block diagram showing an electrical configuration of the substrate coating apparatus shown in FIG. 1A; FIG. 1B is an external perspective view showing an example of a slit nozzle used in the substrate coating apparatus shown in FIG. 1A; FIG. 4 is a diagram showing the configuration of a processing liquid supply unit; FIG. It is a figure which shows typically the relative movement operation|movement of the slit nozzle with respect to a board|substrate in the board|substrate coating apparatus shown to FIG. 1A and FIG. 1B. It is a figure which shows the coating condition when coating processing is performed with a fixed scanning speed like a prior art in the board|substrate coating device shown to FIG. 1A and FIG. 1B. FIG. 4 is a diagram schematically showing the relationship between a meniscus formed between a substrate and an ejection port and a coating gap; FIG. 10 is a graph showing the overlap distance and the rate of change of the overlap distance with respect to the scan distance; FIG. BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows 1st Embodiment of the board|substrate coating method which concerns on this invention. It is a figure which shows 2nd Embodiment of the board|substrate coating method which concerns on this invention. It is a figure which shows 3rd Embodiment of the board|substrate coating method which concerns on this invention. It is a figure which shows 4th Embodiment of the board|substrate coating method which concerns on this invention.

FIG. 1A is a diagram showing the configuration of a substrate coating apparatus to which the first embodiment of the substrate coating method according to the present invention can be applied. Moreover, FIG. 1B is a block diagram showing an electrical configuration of the substrate coating apparatus shown in FIG. 1A. This substrate coating apparatus 100 coats a surface Wf of a substantially disk-shaped substrate W such as a semiconductor wafer with a processing liquid by a so-called capillary method. In addition, in FIG. 1A, an XYZ orthogonal coordinate system having the Z direction as the vertical direction and the XY plane as the horizontal plane is appropriately attached in order to clarify the directional relationship of each part of the coating unit. Also, for the purpose of facilitating understanding, the dimensions and numbers of each part are exaggerated or simplified as necessary.

The substrate coating apparatus 100 is an apparatus called a slit coater that applies a processing liquid to the front surface Wf of the substrate W using the slit nozzle 2 . The treatment liquid includes, for example, a resist liquid, a color filter liquid, polyimide, silicon, nanometal ink, slurry containing a conductive material, and the like. This substrate coating apparatus 100 includes a stage 1 capable of sucking and holding a substrate W in a horizontal posture, a slit nozzle 2 discharging a processing liquid onto the substrate W held on the stage 1, and a process for supplying the processing liquid to the slit nozzle 2. A liquid supply unit 3, a nozzle moving mechanism 4 for moving the slit nozzle 2 with respect to the substrate W, and a control unit 5 for controlling the entire apparatus are provided.

The stage 1 is made of stone material such as granite having a substantially rectangular parallelepiped shape, and the (+X) side of its surface (+Z side) is processed into a substantially horizontal flat surface to hold the substrate W. 11. A large number of vacuum suction ports (not shown) are dispersedly formed on the holding surface 11 . By sucking the substrate W by these vacuum suction ports, the substrate W is held substantially horizontally at a predetermined position during the coating process. The manner in which the substrate W is held is not limited to this. For example, the substrate W may be held mechanically.

FIG. 2 is an external perspective view showing an example of a slit nozzle used in the substrate coating apparatus shown in FIG. 1A. The slit nozzle 2 has a structure in which a first main body portion 21, a second main body portion 22 and a shim plate 23 are connected to each other by a plurality of fixing screws (not shown). More specifically, the slit nozzle 2 is configured by connecting the first body portion 21 and the second body portion 22 so as to face each other in the X direction with the shim plate 23 interposed therebetween.

The first main body portion 21 and the second main body portion 22 are machined, for example, from metal blocks such as stainless steel and aluminum. Also, the shim plate 23 is a thin plate member made of a similar metal material.

The main surface of the first main body portion 21 facing the second main body portion 22, that is, the main surface on the (+X) side is finished to be a first flat surface parallel to the YZ plane. A lower portion of the first body portion 21 protrudes downward to form a first lip portion 21c. A substantially semi-cylindrical groove (not shown) having a longitudinal direction in the Y direction and a depth direction in the X direction is provided in the central portion of the first flat surface in the Z direction. This groove functions as a manifold in the flow path of the coating liquid, and is connected to the processing liquid supply section 3 via the coating liquid supply port (reference numeral 25 in FIG. 3).

On the other hand, the main surface of the second body portion 22 facing the first body portion 21, that is, the main surface on the (-X) side is a second flat surface parallel to the YZ plane. A lower portion of the second main body portion 22 protrudes downward to form a second lip portion 22c. The first main body portion 21 and the second main body portion 22 are coupled via a shim plate 23 such that the first flat surface and the second flat surface face each other with a space therebetween.

When the first main body portion 21 and the second main body portion 22 are joined, the first flat surface and the second flat surface face each other in parallel with a small gap corresponding to the thickness of the shim plate 23. It will happen. The gap portion between the opposing surfaces (the first flat surface and the second flat surface) facing each other in this manner serves as a flow path for the coating liquid from the manifold, and the lower end of the gap portion opens downward toward the surface Wf of the substrate W. It functions as the ejection port 24 . The ejection port 24 has a longitudinal direction in the Y direction and a minute dimension in the X direction.

The shim plate 23 is formed in an inverted U shape opening downward. By inserting the shim plate 23 in the gap between the first main body portion 21 and the second main body portion 22, the upper end portion above the groove and both side end portions in the Y direction of the gap space are shim plates. 23 is blocked. As a result, the space that is not blocked by the shim plate 23 in the gap space defines the flow path of the coating liquid that connects the groove as the manifold and the discharge port 24 . In other words, the shim plate 23 has a notched portion that serves as a flow path for the application liquid, and has a shape that surrounds the flow path for the application liquid other than the ejection port.

FIG. 3 is a diagram showing the configuration of the processing liquid supply unit. As shown in the figure, the treatment liquid supply unit 3 uses a pump 31 as a supply source for supplying the treatment liquid to the slit nozzle 2. The pump 31 supplies the treatment liquid by volume change. As the pump 31, for example, a bellows type pump described in JP-A-10-61558 can be used. This pump 31 has a flexible tube 311 that can be elastically expanded and contracted in the radial direction. One end of this flexible tube 311 is connected to the treatment liquid replenishing unit 33 via a pipe 32 , and the other end is connected to the coating liquid supply port 25 of the slit nozzle 2 via a pipe 34 .

A bellows 312 that is elastically deformable in the axial direction is arranged outside the flexible tube 311 . The bellows 312 has a small bellows portion 313 and a large bellows portion 314, and a pump chamber 315 between the flexible tube 311 and the bellows 312 contains an incompressible medium. A working disk portion 316 is provided between the small bellows portion 313 and the large bellows portion 314 . A driving portion 317 is connected to the operating disk portion 316 . When the driving portion 317 operates in response to a command from the control portion 5 , the operating disk portion 316 is displaced, for example, to one side in the axial direction to change the inner volume of the bellows 312 . As a result, the flexible tube 13 expands and contracts in the radial direction to perform a pumping operation, and the processing liquid replenished appropriately from the processing liquid replenishing unit 33 is fed toward the slit nozzle 2 . Conversely, when the working disk portion 316 is displaced, for example, to the other side in the axial direction to change the inner volume of the bellows 312 , the processing liquid in the slit nozzle 2 is sucked toward the processing liquid replenishing unit 33 . Further, as will be described later, when the slit nozzle 2 moves in the (+X) direction with respect to the substrate W, the working disk portion 316 is displaced to the other side in the axial direction, so that the processing liquid flowing toward the slit nozzle 2 is displaced. A supply reduction operation is executed in which a part of the processing liquid is pulled back, thereby reducing the amount of processing liquid supplied to the slit nozzle 2 . Thus, the pump 31 corresponds to an example of the "flow rate adjusting section" of the present invention.

The processing liquid replenishing unit 33 has a storage tank 331 that stores the processing liquid. This storage tank 331 is connected to the pump 31 through a pipe 32 . An on-off valve 333 is inserted in the pipe 32 . The on-off valve 333 is opened in response to a replenishment command from the control unit 5 to allow the flexible tube 311 of the pump 31 to be replenished with the treatment liquid in the storage tank 331 . Conversely, it is closed in response to a replenishment stop command from the control unit 5 to restrict replenishment of processing liquid from the storage tank 331 to the flexible tube 311 of the pump 31 .

An on-off valve 35 is inserted in a pipe 34 connected to the output side of the pump 31 (on the left hand side in the figure), and is opened and closed according to an open/close command from the controller 5 . As a result, it is possible to switch between the feeding of the processing liquid to the slit nozzle 2, the suction of the processing liquid from the slit nozzle 2, the stop of the liquid feeding, and the stop of the suction. Further, a pressure gauge 36 is attached to the pipe 34 to detect the pressure of the processing liquid sent to the slit nozzle 2 and output the detection result (pressure value) to the control section 5 .

In the processing liquid supply unit 3 configured as described above, the slit nozzle 2 discharges at a position above the edge of the substrate W in the (−X) direction (“coating start position P1” in FIG. 4 to be described later). When the outlet 24 is brought close to the surface Wf of the substrate W and the processing liquid is deposited on the surface Wf, the operation is as follows. That is, the on-off valve 333 is closed and the on-off valve 35 is opened according to the open/close command from the control unit 5 , and the pump 31 is operated according to the liquid feed command from the control unit 5 . As a result, the processing liquid is sent toward the slit nozzle 2 by the pump 31, and a bead (liquid pool) of the processing liquid is formed between the discharge port 24 and the surface Wf of the substrate W. As shown in FIG.

Further, in this embodiment, since the front surface Wf of the substrate W is a semiconductor wafer having a substantially circular shape, the processing liquid is applied by the capillary method, as in the apparatus described in Patent Document 1. In other words, the on-off valve 333 is opened in response to the open/close command from the controller 5 and the operation of the pump 31 is stopped in response to the liquid feed stop command from the controller 5 . Then, the slit nozzle 2 is moved relative to the substrate W from the (-X) direction side to the (+X) direction side by the nozzle moving mechanism 4 while bringing the discharge port 24 close to the front surface Wf of the substrate W. FIG. The treatment liquid is ejected from the ejection port 24 by the surface tension of the treatment liquid (bead of the treatment liquid) generated between the ejection port 24 and the substrate W during this movement. For this reason, the processing liquid is discharged from the portions of the discharge ports 24 extending in the Y direction that face the substrate W, while the processing liquid is not discharged from the portions where the substrate W does not exist. Such a change in ejection state occurs as the slit nozzle 2 moves in the X direction relative to the substrate W by the nozzle moving mechanism 4 . When the application of the processing liquid to the substrate W is completed in this way, the slit nozzle 2 moves upward from the substrate W and then returns from the (+X) direction to the (−X) direction.

Returning to FIGS. 1A and 1B, the description of the configuration is continued. The nozzle moving mechanism 4 has a bridge structure nozzle support 41 that supports the slit nozzle 2 while traversing above the stage 1 in the Y direction, and a nozzle moving unit 42 that horizontally moves the nozzle support 41 in the X direction. . Therefore, the slit nozzle 2 supported by the nozzle support 41 can be horizontally moved in the X direction by the nozzle moving part 42 . Thus, in this embodiment, the nozzle moving section 42 corresponds to an example of the "moving section" of the present invention.

The nozzle support 41 has a fixed member 41a to which the slit nozzle 2 is fixed, and two elevating mechanisms 41b that support and lift the fixed member 41a. The fixing member 41a is a rod-shaped member having a rectangular cross section whose longitudinal direction is the Y direction, and is made of carbon fiber reinforced resin or the like. The two elevating mechanisms 41b are connected to both ends of the fixed member 41a in the longitudinal direction, and each have an AC servomotor, a ball screw, and the like. By these lifting mechanisms 41b, the fixing member 41a and the slit nozzle 2 are integrally lifted up and down in the vertical direction (Z direction), and the distance between the discharge port 24 of the slit nozzle 2 and the surface Wf of the substrate W, that is, the substrate W The separation distance (hereinafter referred to as "coating gap") of the ejection port 24 from the surface Wf of is adjusted. The position of the slit nozzle 2 in the Z direction can be detected by a linear encoder (not shown).

The nozzle moving unit 42 includes two guide rails 43 that guide the movement of the slit nozzle 2 in the X direction, two linear motors 44 that are driving sources, and a nozzle for detecting the position of the ejection port of the slit nozzle 2. Two linear encoders 45 are provided.

The two guide rails 43 are arranged at both ends of the stage 1 in the Y direction so as to sandwich the mounting range of the substrate W from the Y direction, and extend in the X direction so as to include the mounting range of the substrate W. ing. The slit nozzle 2 moves in the X direction above the substrate W held on the stage 1 by guiding the lower ends of the two lifting mechanisms 41b along the two guide rails 43, respectively.

Each of the two linear motors 44 is an AC coreless linear motor having a stator 44a and a mover 44b. The stators 44a are provided on both sides of the stage 1 in the Y direction along the X direction. On the other hand, the mover 44b is fixed to the outside of the lifting mechanism 41b. The linear motor 44 functions as a drive source for the nozzle moving mechanism 4 by magnetic force generated between the stator 44a and the mover 44b.

Each of the two linear encoders 45 has a scale portion 45a and a detection portion 45b. The scale portion 45a is provided along the X direction under the stator 44a of the linear motor 44 fixed to the stage 1. As shown in FIG. On the other hand, the detector 45b is fixed further outside the mover 44b of the linear motor 44 fixed to the lifting mechanism 41b, and arranged to face the scale 45a. The linear encoder 45 detects the position of the ejection port of the slit nozzle 2 in the X direction (corresponding to the nozzle movement direction or relative movement direction) based on the relative positional relationship between the scale portion 45a and the detection portion 45b.

As shown in FIG. 1B, the control unit 5 for controlling the substrate coating apparatus 100 configured as described above stores a calculation unit 51 (for example, a CPU) that performs various calculation processes, a basic program, and various information. It has a configuration of a general computer system in which a storage unit 52 (for example, ROM, RAM, etc.) is connected to a bus line. The bus line is also connected to a fixed disk 53 (for example, a hard disk drive) for storing application programs and the like. Moreover, the processing liquid supply unit 3, the nozzle moving mechanism 4, and the input display unit 6 are appropriately connected via an interface (I/F). The input display unit 6 displays various types of information and accepts input from the operator, and is composed of, for example, a touch panel display. Of course, instead of the input display unit 6, a display for displaying various information and a keyboard or mouse for receiving input from the operator may be used.

In the control unit 5 , the application program stored in the fixed disk 53 in advance is copied to the storage unit 52 (for example, RAM), and the calculation unit 51 executes calculation processing according to the application program in the storage unit 52 . As a result, the processing liquid is discharged from the discharge port 24 of the slit nozzle 2 at an appropriate timing by the control of the processing liquid supply unit 3, and the supply reduction operation and the slit nozzle 2 at a constant speed are controlled by the control of the nozzle moving mechanism 4. An X direction scan is performed. As a result, the surface Wf of the substrate W is coated with the processing liquid in a desired film thickness. Thus, the calculation unit 51 of the control unit 5 functions as the nozzle scanning unit 512 and the supply reduction unit 513 . In particular, the supply reduction unit 513 controls the supply reduction operation based on the analysis results detailed below. More specifically, the overlapping distance (marked L in FIGS. 5 and 8) at which the discharge port 24 and the substrate W overlap in the longitudinal direction Y when viewed from above is the relative movement of the slit nozzle 2 with respect to the substrate W (X During the period in which the amount of processing liquid supplied to the slit nozzle 2 decreases with the X-direction scanning (that is, the overlapping decrease period), the amount of processing liquid supplied to the slit nozzle 2 is reduced in accordance with the change in the overlapping distance L as the slit nozzle 2 scans in the X direction. , controls the processing liquid supply unit 3 . This supply reduction operation enhances the film thickness uniformity of the processing liquid.

Here, in order to explain the reason why the supply reduction operation is excellent, first, the substrate coating apparatus 100 configured as described above maintains a constant coating gap and scans at a constant scanning speed, as in the prior art. A case where the coating process is executed will be described with reference to FIGS. 4 to 6. FIG. Among them, in the prior art, the reason why the film thickness defect occurs in the latter round portion (symbol PT4 in FIG. 4) of the substrate W will be considered, and specific means for solving the problem will be described. After that, specific operations of the substrate coating apparatus 100 will be described.

4A and 4B are diagrams schematically showing relative movement of the slit nozzle with respect to the substrate in the substrate coating apparatus shown in FIGS. 1A and 1B. In FIG. It is illustrated divided into five types. Here, a semiconductor wafer with a diameter of 300 mm is used as the substrate W, and the case where the slit nozzle 2 scans the substrate W in the X direction is illustrated. That is, in the substrate coating apparatus 100, the ejection port 24 starts coating from a state in which the ejection port 24 is positioned at the coating start position P1 above one end (−X direction side end) of the substrate W in the coating direction X. After passing through a wide position P2 separated from the position P1 by a radius r (r=150 mm in this embodiment) of the substrate W, the ejection port 24 finishes coating above the other end (+X direction side end) of the substrate W. The slit nozzle 2 is scanned with respect to the substrate W until it is positioned at the position P3.

Further, in this specification, for convenience of explanation, as shown in the lower part of FIG. It is divided into "wide part PT3", "second half round part PT4" and "application end part PT5". That is, of the surface peripheral edge region of the substrate W, the peripheral edge supply region that receives the treatment liquid supply when the slit nozzle 2 is positioned at the coating start position P1 is the coating start portion PT1. Also, the part to which the treatment liquid is supplied while the slit nozzle 2 moves from the coating start position P1 to the wide position P2 is the first round part PT2. A wide portion PT3 is a portion to which the processing liquid is supplied when the slit nozzle 2 is positioned at the wide position P2. Further, the part to which the treatment liquid is supplied while the slit nozzle 2 moves from the wide position P2 to the coating end position P3 is the latter round part PT4. Furthermore, the peripheral edge supply region to which the treatment liquid is supplied when the slit nozzle 2 is positioned at the coating end position P3 is the coating end portion PT5.

"0", "150", and "300" in FIG. 4 indicate the moving distance of the slit nozzle 2 from the application start position P1. Reference symbols G(0), G(150), and G(300) denote coating gaps when the slit nozzle 2 is positioned at the coating start position P1, the wide position P2, and the coating end position P3, respectively.

FIG. 5 is a diagram showing the state of coating when the substrate coating apparatus shown in FIGS. 1A and 1B performs coating processing at a constant scanning speed as in the prior art. Columns (A) to (C) in the figure show the slit nozzle 2, the substrate W, and the processing liquid upward in the (−Y) direction when the slit nozzle 2 is positioned at six different positions SLa to SLf. and (+X) directions are schematically shown. At the position SLa among these positions, the slit nozzle 2 is positioned in the (-X) direction from the coating start position P1 and away from the substrate W in the (-X) direction. At the position SLb, the slit nozzle 2 is positioned at the coating start position P1. On the other hand, a position SLf indicates a position that is separated from above the other end of the substrate W by 300 mm or more from the position SLb (coating start position P1) in the coating direction (+X). , and particularly at the position SLd, the slit nozzle 2 is positioned at the wide position P2. Further, in these drawings, the regions coated with the treatment liquid are schematically indicated by hatching. Note that these points also apply to FIG. 8, which will be described later.

Next, in the substrate coating apparatus 100, when the conventional coating operation, that is, the coating process is performed while the slit nozzle 2 is moved at a constant scanning speed while the pump 31 is stopped and the on-off valves 35 and 333 are opened, The following problems may occur. When the substrate W is transported to the substrate coating apparatus 100 by a transport robot (not shown), a lift pin (not shown) rises from the central portion of the stage 1 to support the back surface of the substrate W. As shown in FIG. Following this, the transfer robot retreats from the substrate coating apparatus 100 . As a result, the substrate W is delivered to the lift pins. After that, the lift pins descend into the stage 1 and the substrate W is placed on the holding surface 11 of the stage 1 and held on the holding surface 11 of the stage 1 by a suction mechanism (not shown).

In the substrate coating apparatus 100, the slit nozzle 2 is moved from the position SLa away from the substrate W held on the holding surface 11 in the (-X) direction to a position suitable for the coating process, and is shown in the column "SLb" in FIG. , the slit nozzle 2 is positioned at the coating start position P1. Before the start of the coating process, in a state in which the coating gap is adjusted to a predetermined value at the coating start position P1, the on-off valve 333 is temporarily closed while the on-off valve 35 is kept open, and the pump 31 is temporarily operated. do. As a result, a bead of the treatment liquid is formed between the ejection port 24 and the surface Wf of the substrate W. As shown in FIG. After bead formation, the on-off valve 333 is opened and the pump 31 is stopped. Therefore, the processing liquid flows through the pipe 32 according to the pressure difference between the two ends of the pipe 32 .

When the coating process is started, while the slit nozzle 2 moves in the (+X) direction while maintaining a constant coating gap, the processing liquid LD supplied from the processing liquid supply unit 3 is discharged from the discharge port 24 . At this time, the processing liquid is supplied to the slit nozzle 2 through the pipe 32 by the surface tension of the processing liquid LD (bead of the processing liquid) generated between the discharge port 24 and the substrate W. FIG. That is, as the coating process progresses, a negative pressure is generated in the slit nozzle 2 , and the treatment liquid flows through the pipe 32 from the storage tank 331 side to the slit nozzle 2 side and is discharged from the discharge port 24 . Thereby, the surface Wf of the substrate W is coated with the processing liquid LD. The slit nozzle 2 moves in the (+X) direction while being maintained at a constant scanning speed. The discharge width (liquid contact range) gradually widens. Then, the slit nozzle 2 is maximized at the position SLd (that is, the wide position P2).

When the slit nozzle 2 passes through the central portion of the substrate W and further moves in the (+X) direction, the overlapping distance L (discharge width of the processing liquid) gradually narrows and becomes above the edge of the substrate W in the (+X) direction. The final application of the treatment liquid LD is performed when the position, that is, the application end position P3 is reached. When the slit nozzle 2 moves further in the (+X) direction from the coating end position P3 and is positioned at the position SLf, the movement of the slit nozzle 2 is stopped.

In this way, the coating process is performed. Particularly, during the period when the slit nozzle 2 is moving from the wide position P2 (position SLd) to the coating end position P3, the overlapping distance L changes as the slit nozzle 2 moves. Decrease. In other words, this period is an overlapping reduction period. During this overlap reduction period, the overlap distance L, that is, the discharge width (liquid contact range) of the treatment liquid LD gradually decreases. It tries to narrow to the central part side. However, the narrowing motion cannot be followed, and as shown in FIG. The meniscus M1 (solid line in the figure) is shifted outward from the ideal meniscus M0 (chain line in the figure) for thick coating. That is, the processing liquid LD spreads excessively in the longitudinal direction Y with respect to the scanning movement of the slit nozzle 2, and excessive processing liquid LD exists as indicated by dots in the figure.

Moreover, since the surface Wf of the substrate W is substantially circular, as shown in FIG. However, the amount of processing liquid supplied to the slit nozzle 2 through the pipe 32 is not controlled. As a result, in the prior art, as shown in the "SLf" column in FIG. 5, the film thickness at the portion corresponding to the second half round portion PT4 may eventually become thicker than the set value, that is, excessive film thickness NG may occur. there were.

Therefore, the inventors of the present application have concluded that the above problem can be solved by reducing the amount of the processing liquid supplied to the slit nozzle 2 through the pipe 32 according to the change in the overlapping distance L. Arrived. Hereinafter, the contents of the analysis of the change in the overlap distance L during the overlap reduction period will be described with reference to FIG. 7, and then the coating operation of the substrate coating apparatus 100 based on the analysis results will be described with reference to FIG.

FIG. 7 is a graph showing the overlap distance and the rate of change of the overlap distance with respect to the scan distance. Here, the "scanning distance" means the distance from the (-X) end of the substrate W in the coating direction X, that is, the moving distance of the slit nozzle 2 from the position SLb (coating start position P1). By differentiating the function shown in the graph shown in the middle of the figure (the graph showing the change in the overlap distance L with respect to the scan distance), the change speed of the overlap distance L can be obtained as shown in the lower part of the figure. In order to prevent the excessive film thickness NG from occurring, it is important to make the narrowing of the processing liquid LD between the substrate W and the discharge port 24 correspond to the changing speed of the overlap distance L during the overlap reduction period. be. As is clear from these graphs, the overlapping distance L sharply increases from the start of movement from the position SLb (coating start position P1), and the scanning distance is half the substrate size (300 mm in this embodiment) at the position SLd ( It becomes maximum at the wide position P2). Then, while the scanning distance is further increased, that is, while the slit nozzle 2 is moving above the (+X) direction edge of the substrate W (coating end position P3), the overlapping distance L is shortened at a rapid change speed. there is That is, during the overlap decrease period (scanning distance 150 mm to 300 mm), the decrease rate of the overlap distance L increases exponentially. Therefore, even in the overlap reduction period, especially in the final stage when the overlap distance L is rapidly reduced, the excess processing liquid LD (dotted in FIG. 6) is not generated following it, and the longitudinal direction is not generated. It is preferable to reduce the supply amount of the processing liquid LD supplied to the slit nozzle 2 through the pipe 32 in order to narrow the processing liquid LD to the central portion of the ejection port 24 in Y. That is, during the overlap reduction period, the coating gap changes corresponding to the change in the overlap distance L, that is, the function that shows the change in the overlap distance L during the overlap reduction period,
L=2×√{r ² −(r−x) ² }
however,
x is the scan distance by which the slit nozzle 2 has moved relative to the substrate W from the coating start position P1 toward the wide position P2.
It is preferable that the control unit 5 controls the pump 31 based on.

More specifically, when the change in the overlap distance L during the overlap decrease period is partially extracted, as shown in the upper part of FIG. When minutely moving to the position of , the amount of change ΔL in the overlapping distance L is
ΔL = Ln - Ln-1
however,
Ln is the overlapping distance when the slit nozzle 2 is positioned at the scan distance xn,
Ln-1 is the overlap distance when the slit nozzle 2 is positioned at the scan distance xn-1,
becomes. Therefore, the supply reduction speed SR(x) when the slit nozzle 2 is positioned at the scan distance Xn is given by the following equation:
SR(x)=-ax(Ln-Ln-1)/(xn-xn-1)+b... Formula (1)
however,
a and b are constants,
It is desirable that the control unit 5 controls the pump 31 so as to satisfy As a result, the narrowing of the processing liquid LD in the longitudinal direction Y is properly controlled by suppressing the excessive processing liquid LD (dotted in FIG. 6) between the substrate W and the ejection port 24 during the overlapping reduction period. become. As a result, it is possible to effectively prevent the occurrence of excessive film thickness NG in the latter round portion PT4. In the present embodiment, as shown in FIG. 8, the coating process is performed while controlling the supply reduction speed SR(x) so that the above formula (1) is satisfied during the overlap reduction period.

FIG. 8 is a diagram showing a first embodiment of the substrate coating method according to the present invention. The difference between this first embodiment and the prior art is that, as indicated by the solid line in the upper graph of FIG. The other configuration is the same as the prior art. The above-mentioned "supply reduction speed" refers to a supply reduction operation in which part of the processing liquid flowing through the pipe 32 is pulled back to the storage tank 331 side by the operation of the pump 31 to reduce the amount of processing liquid supplied to the slit nozzle 2 side. means the amount of processing liquid reduced per unit time.

In the first embodiment, as shown in FIGS. 4 and 8, the pump 31 is stopped while the slit nozzle 2 scans from the coating start position P1 to the wide position P2. is maintained at zero, the scanning movement of the slit nozzle 2 is performed. While the slit nozzle 2 is scanning from the wide position P2 (scanning distance 150 mm) to the coating end position P3 (scanning distance 300 mm) in the X direction, the controller 5 controls the supply reduction speed SR ( x) is increased. For this reason, immediately before the end of coating, although the overlapping distance L changes rapidly, the amount of processing liquid supplied to the slit nozzle 2 is kept small by correspondingly increasing the supply reduction speed SR(x). there is Therefore, excess processing liquid LD (dotted in FIG. 6) is suppressed, and narrowing of the processing liquid LD in the longitudinal direction Y is optimized by following changes in the overlapping distance L. FIG. As a result, it is possible to effectively prevent the occurrence of excessive film thickness NG in the latter round portion PT4.

As described above, according to the present embodiment, during the overlapping reduction period, an appropriate amount of the processing liquid LD exists between the ejection port 24 of the slit nozzle 2 and the surface Wf of the substrate W, and the excess film thickness NG is present at the latter round portion PT4. can be effectively prevented from occurring. On the other hand, the first half of the coating process (the period in which the slit nozzle 2 moves from the coating start position P1 to the wide position P2) is a period in which the overlap distance L increases, and the problem that occurred during the overlap decrease period naturally occurs. not, the supply curtailment rate SR(x) is set to zero. As a result, the entire substrate W can be uniformly coated with the processing liquid.

By the way, in the above-described first embodiment, as shown in the solid line pattern in FIG. 8, the supply reduction speed is changed in a curved line shape. (second embodiment). Regarding this point, the same applies to the embodiments described below.

Moreover, the processing liquids to which the present invention is applicable are diverse as described above, and the processing liquids having the property of spreading relatively quickly on the surface Wf of the substrate W are also included in the subject of the present invention. When a treatment liquid having such characteristics is applied by a capillary method, an excessive film thickness NG may occur in the first round portion PT2. Therefore, the supply reduction operation may also be applied to the first half of the coating process (the range where the overlapping distance increases) (third embodiment).

FIG. 10 is a diagram showing a third embodiment of the substrate coating method according to the present invention. The third embodiment differs from the first embodiment in that, as indicated by the solid line in the upper graph of FIG. The other configuration is the same as that of the first embodiment except that the supply reduction operation is executed even during the time when the power consumption increases (that is, the overlapping increase period).

As described above, in the third embodiment, the controller 5 increases the supply reduction speed SR(x) according to the formula (1) during the overlapping increase period in which the slit nozzle 2 scans from the coating start position P1 to the wide position P2. ing. Therefore, immediately after the start of coating, although the overlapping distance L changes rapidly, the amount of processing liquid supplied to the slit nozzle 2 is kept small due to the corresponding increase in the supply reduction speed SR(x). there is Therefore, excess processing liquid LD (dotted in FIG. 6) is suppressed, and narrowing of the processing liquid LD in the longitudinal direction Y is optimized by following changes in the overlapping distance L. FIG. As a result, it is possible to effectively prevent the occurrence of excessive film thickness in the first round portion PT2. In addition, the supply reduction operation is executed during the overlapping reduction period as well, as in the first embodiment. As a result, the entire substrate W can be uniformly coated with the processing liquid.

In the above-described third embodiment, the supply reduction operation is started immediately after the start of coating. Good (fourth embodiment). The fourth embodiment will be described below with reference to FIG.

FIG. 11 is a diagram showing a fourth embodiment of the substrate coating method according to the present invention. The major difference between the fourth embodiment and the third embodiment is that the bead adjustment operation is performed before starting coating, and the rest of the configuration is the same as that of the third embodiment. Therefore, the following description will focus on the points of difference, and the same reference numerals will be assigned to the same configurations, and description thereof will be omitted.

In the fourth embodiment, focusing on the point that the pump 31 has both the liquid feeding function and the suction function, the control section 5 controls the processing liquid supply section 3 as follows to execute the bead forming operation. That is, before the start of application (before the start of movement of the slit nozzle 2), the on-off valve 333 is closed and the on-off valve 35 is opened in accordance with the open/close command from the control unit 5, and furthermore, in accordance with the liquid feeding command from the control unit 5. Pump 31 is activated. In the above-described embodiment, as indicated by the dotted line in the figure, the pump 31 pressure-feeds the processing liquid to the slit nozzle 2 at a supply amount SM1 necessary to form a bead suitable for the coating process, thereby forming a bead of the processing liquid. Form.

In contrast, in the fourth embodiment, the bead is formed in two steps while the slit nozzle 2 remains positioned at the position SLb (coating start position P1). More specifically, the control unit 5 sends a liquid feeding command to the pump 31, and controls the pump 31 to pressure-feed the processing liquid to the slit nozzle 2 at a supply amount SM4 larger than the supply amount SP1 (large bead forming process). As a result, as shown in the leftmost column of the figure, a bead B2 slightly larger than the bead B1 suitable for coating treatment is formed. Subsequently, the controller 5 sends a suction command to the pump 31, and controls the pump 31 to pull back the treatment liquid from the slit nozzle 2 by a predetermined suckback amount SB4 (suckback process). As a result, a suckback amount SB4 of the treatment liquid is removed from the bead B2, thereby forming a bead B1 suitable for the coating treatment, as shown second from the left in the figure.

As described above, according to the fourth embodiment, since an appropriate bead is formed in two steps of the large bead forming process and the suckback process, the following effects can be obtained. The bead B1 must be controlled according to the film thickness. Therefore, in order to form a thin film, the amount of the treatment liquid forming the bead B1 is also reduced. Difficult to control accurately.

Further, in the case where the substrate W is a substantially circular substrate such as a semiconductor wafer, the area where the bead B1 is formed has a small coverage area of the processing liquid on the surface Wf of the substrate W. As shown in FIG. Therefore, it is difficult to form the bead B1 in a fine liquid landing area while ejecting a small amount of the treatment liquid from the ejection port 24 wide in the Y direction. Here, in order to stabilize the bead, for example, as shown in the leftmost column of FIG. It is desirable to form the bead B2 so as to exhibit By sucking a part of the treatment liquid from the bead B2 thus stably formed, the bead B1 can be easily shaped into a desired shape.

The present invention is not limited to the above-described embodiments, and various modifications other than those described above can be made without departing from the spirit of the present invention. For example, in the fourth embodiment, a two-step bead forming operation is applied to the third embodiment, but it is also applicable to the first and second embodiments.

Further, in the first to third embodiments, the pump 31 is used as the "flow rate adjusting unit" of the present invention, but the supply reduction speed may be controlled by other means. For example, an electromagnetic needle valve may be interposed in the pipe 32, and the control unit 5 may control the supply reduction speed by adjusting the valve opening of the electromagnetic needle valve. Also, the supply reduction speed may be controlled by adjusting the pressure in the storage tank 331 .

In the above embodiment, the present invention is applied to a substrate coating technique for coating the processing liquid LD on a substrate W such as a semiconductor wafer having a substantially circular surface Wf, but the type of substrate W is limited to this. not to be For example, the present invention can also be applied to a substrate application technique for applying the processing liquid LD to a substrate W whose surface Wf is finished in a rhombus, regular pentagon, regular hexagon, or the like. In short, a substrate coating technique in which the slit nozzle 2 is moved relative to the substrate W in the coating direction X so that the processing liquid LD is discharged from the discharge port 24 of the slit nozzle 2 onto the surface Wf of the substrate W for coating. Of these, the present invention can be applied to the case where the overlapping distance L where the discharge port 24 and the substrate W overlap in the longitudinal direction Y in a plan view from above changes with the relative movement of the slit nozzle 2 with respect to the substrate W. can be done.

Further, in the above-described embodiment, while the substrate W is fixed and the slit nozzle 2 is moved in the coating direction X, the processing liquid LD is coated, but the coating mode is not limited to this. For example, the substrate W may be moved while the slit nozzle 2 is fixed. Moreover, both the slit nozzle 2 and the substrate W may be moved to apply the treatment liquid LD. In short, the present invention can be applied to general substrate coating techniques in which the slit nozzle 2 is moved relative to the substrate W to perform the coating process.

According to the present invention, the slit nozzle is moved relative to the substrate in the coating direction while supplying the treatment liquid from the ejection port of the slit nozzle arranged above the surface of the substrate to the surface of the substrate. It can be applied to general substrate coating in which a processing liquid is applied to the surface.

Reference Signs List 2 Slit nozzle 3 Treatment liquid supply unit 5 Control unit 24 Discharge port (of slit nozzle) 31 Pump (flow rate adjustment unit)
32... Piping 42... Nozzle moving part (moving part)
DESCRIPTION OF SYMBOLS 100... Substrate coating apparatus 331... Storage tank L... Overlapping distance LD... Processing liquid P1... Application start position P2... Wide position P3... Application end position W... Substrate Wf... Surface (of substrate) X... Application direction Y... Longitudinal direction

Claims (10)

A substrate coating apparatus for coating a surface of a substrate with a processing liquid,
a slit nozzle having a slit-shaped ejection opening facing the surface of the substrate;
a moving unit that relatively moves the slit nozzle with respect to the substrate in a coating direction orthogonal to the longitudinal direction of the ejection port;
a processing liquid supply unit capable of supplying the processing liquid to the slit nozzle as the slit nozzle moves relative to the slit nozzle;
a control unit that controls the processing liquid supply unit and the moving unit;
The treatment liquid supply unit is capable of executing a supply reduction operation for reducing the supply amount of the treatment liquid to the slit nozzle,
The control unit performs the supply reduction operation in accordance with a change in an overlapping distance between the discharge port and the substrate in the longitudinal direction in plan view from above as the slit nozzle is moved relative to the substrate. A substrate coating apparatus, wherein the processing liquid supply unit is controlled such that The substrate coating apparatus according to claim 1,
When the amount of the processing liquid reduced per unit time by the supply reduction operation is defined as a supply reduction rate,
The control unit controls the processing liquid supply unit such that, while the overlap distance decreases as the slit nozzle moves relative to the substrate, the supply reduction speed increases as the overlap distance decreases. substrate coating equipment. The substrate coating apparatus according to claim 2,
The substrate coating apparatus, wherein the control section controls the processing liquid supply section based on a function indicating a decrease in the overlapping distance accompanying relative movement of the slit nozzle with respect to the substrate. The substrate coating apparatus according to claim 3,
When the surface of the substrate has a substantially circular shape with a radius of r,
The control unit moves the slit nozzle from a state in which the slit nozzle is positioned at a coating start position above one end of the substrate in the coating direction to a wide position separated by the radius r from the coating start position. controlling the moving part so that the slit nozzle moves relative to the substrate until the slit nozzle is positioned at the coating end position above the other end of the substrate through the
The function is
L=2×√{r ² −(r−x) ² }
however,
L is the overlap distance;
x is the distance that the slit nozzle has moved relative to the substrate from the coating start position to the coating end position via the wide position;
Substrate coating equipment. The substrate coating apparatus according to claim 4,
The control unit
Between the wide position and the coating end position, when the slit nozzle slightly moves from the distance xn-1 to the distance xn in the coating direction, the supply reduction speed SR when the slit nozzle is positioned at the distance Xn (x) is the following formula,
SR(x)=-ax(Ln-Ln-1)/(xn-xn-1)+b
however,
a and b are constants,
Ln is the overlap distance when the slit nozzle is positioned at the distance xn;
Ln-1 is the overlapping distance when the slit nozzle is positioned at the distance xn-1,
A substrate coating apparatus that controls the processing liquid supply unit so as to satisfy The substrate coating apparatus according to any one of claims 2 to 5,
The control unit controls the processing liquid supply unit so that the supply reduction speed increases as the overlap distance increases while the overlap distance increases with relative movement of the slit nozzle with respect to the substrate. substrate coating equipment. The substrate coating apparatus according to any one of claims 2 to 6,
The processing liquid supply unit comprises a storage tank for storing the processing liquid, a pipe for circulating the processing liquid from the storage tank to the slit nozzle, and a flow rate of the processing liquid flowing from the storage tank through the pipe. and a flow rate adjusting unit that controls the supply reduction speed by adjusting the flow rate. The substrate coating apparatus according to claim 7,
The flow rate adjusting unit is a pump inserted in the pipe,
The control unit operates the pump to pull back part of the processing liquid flowing toward the slit nozzle in the pipe during relative movement of the slit nozzle with respect to the substrate, thereby reducing the supply reduction rate. A substrate coating device that controls the The substrate coating apparatus according to claim 8,
The control unit pressure-feeds the processing liquid to the slit nozzle to form a pool of the processing liquid between the ejection port and the substrate before the start of relative movement of the slit nozzle, and then the A substrate coating apparatus for controlling the pump so as to draw back part of the processing liquid from a slit nozzle to optimize the amount of the processing liquid forming the liquid reservoir. While the processing liquid is discharged from a slit-shaped discharge port provided in a slit nozzle arranged above the surface of the substrate, the slit nozzle is positioned relative to the substrate in a coating direction perpendicular to the longitudinal direction of the discharge port. A substrate coating method for applying the processing liquid to the surface of the substrate by moving the substrate to
In a plan view from above, the processing liquid is supplied to the slit nozzle in accordance with the change in the overlapping distance between the discharge port and the substrate in the longitudinal direction as the slit nozzle is moved relative to the substrate. A substrate coating method characterized by executing a supply reduction operation for reducing a supply amount.

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